An ultra-low detection limit strain sensing organic hydrogel fiber and a preparation method and application thereof

Abstract

An ultralow detection limit strain sensing organic hydrogel fiber and a preparation method and application thereof, comprising coaxial wet spinning of a water / organic mixed solution of polyvinyl alcohol and aniline tetramer and sodium alginate, then freezing and crystallizing the organic hydrogel fiber with a skin-core structure in a freezing liquid (dry ice or liquid nitrogen) to assemble and crosslink, and after a period of time, transferring to a freezer for further crosslinking, and finally removing the "skin" structure to obtain a "core" structure polyvinyl alcohol-aniline tetramer organic hydrogel fiber. The organic hydrogel fiber prepared in this way has a three-dimensional nanofiber network structure, good mechanical strength (1.37 MPa), excellent stretchability (643%), and an ultralow strain sensor detection limit (0.01%), and can stably output the deformation signal during human movement, showing great application potential in the field of wearable strain sensors.

Description

Technical Field

[0001] This invention belongs to the technical field of flexible wearable electronic device materials, specifically relating to an ultra-low detection limit strain sensing organic hydrogel fiber, its preparation method, and its application. Background Technology

[0002] In recent years, wearable strain sensors, as electronic devices that convert strain into electrical signals, have received widespread attention in fields such as human motion monitoring, health management, and human-computer interaction. Strain sensors with high sensitivity and a wide detection range are not only suitable for monitoring large-amplitude human movements (deformation greater than 50%), but also for monitoring minute movements such as pulse (deformation less than 1%), attracting considerable interest.

[0003] Organic hydrogels are flexible materials with a three-dimensional network structure and excellent mechanical properties. Their excellent biocompatibility, tunable elasticity, and certain ionic conductivity make them widely used as substrates or functional materials to integrate soft, highly elastic, and highly sensitive strain sensors, making them one of the ideal materials for constructing high-performance flexible wearable strain sensors. The weavability of fibrous organic hydrogels gives them unique advantages in wearable devices, such as good integration with clothing and excellent breathability. However, because the ions in organic gels are uniformly distributed in the system, their detection of small strains is often not ideal, making it difficult to achieve an ultra-low detection limit of 0.01%. Summary of the Invention

[0004] The purpose of this invention is to provide a high-strength, high-toughness, high-strain-sensitive, ultra-low detection limit organic hydrogel fiber, its preparation method, and its application.

[0005] A method for preparing an ultra-low detection limit strain-sensing organic hydrogel fiber includes the following steps:

[0006] Step (1): Prepare solution A: Dissolve the polyvinyl alcohol matrix and acid solution in deionized water and store at room temperature; Prepare solution B: Dissolve the aniline tetramer monomer in an organic solvent and store at room temperature; Solution C: Dissolve sodium alginate in deionized water to obtain the solution for "skin" curing, and inject it into a syringe for later use;

[0007] Step (2): Mix solution A and solution B evenly to obtain a mixed spinning solution. Inject the solution into a syringe as a "core" solution for later use.

[0008] Step (3): The product obtained in step (2) above is coaxially wet-spun with solution C and extruded into a coagulation bath containing non-oxidizing divalent and trivalent metal salts to obtain an organic hydrogel fiber with a core-sheath structure.

[0009] Step (4): The organic hydrogel fibers prepared above are drawn into a freezing liquid (dry ice or liquid nitrogen) for freezing and then transferred to a freezer for cross-linking reaction;

[0010] Step (5): After the reaction is complete, the frozen gel fiber is taken out and thawed to obtain the core-skin structure organic hydrogel fiber. The "skin" structure is dissolved by citrate to obtain the "core" structure organic hydrogel fiber.

[0011] Step (6): Immerse the "core" structure organic hydrogel fiber in an organic solvent / acid solution for several hours, and remove it to reach dehydration equilibrium at room temperature to obtain stretchable, elastic, and conductive organic hydrogel fiber.

[0012] Preferably, the polyvinyl alcohol matrix solution in step (1) of the present invention is an aqueous solution containing 1 to 20 wt% polyvinyl alcohol.

[0013] Preferably, the acid solution in step (1) of the present invention is one or more of hydrochloric acid, sulfuric acid, phosphoric acid or nitric acid solution with a concentration of 0.1 to 6 mol / L.

[0014] Preferably, the organic solvent in step (1) of the present invention is one or more solutions of ethylene glycol, glycerol, pentanediol, acetone, and methanol, and the concentration of the aniline tetramer monomer dissolved in the organic solvent is 0.5 to 100 mg / ml.

[0015] Preferably, the concentration of sodium alginate in step (1) of the present invention is 1–40 wt%.

[0016] Preferably, the non-oxidizing divalent and trivalent metal salts in step (3) of the present invention are one or more of CaCl2, BaCl2 and AlCl3, with a concentration of 0.05 to 0.5 mol / L.

[0017] Preferably, the crosslinking reaction time in the cryosol in step (4) of the present invention is 0.5 to 96 hours.

[0018] Preferably, the freezer defrosting temperature in step (4) of the present invention is -80 to 25°C, and the time is 1 to 96 hours.

[0019] Preferably, the citrate in step (5) of the present invention is one or both of potassium citrate and sodium citrate, and its concentration is 0.05-1.0 mol / L.

[0020] Preferably, the organic solvent / acid solution in step (6) of the present invention is one or more mixed solutions of ethylene glycol, glycerol, pentanediol, acetone, methanol / hydrochloric acid, sulfuric acid, phosphoric acid or nitric acid, and the soaking time is 0.5 to 96 hours.

[0021] An ultra-low detection limit strain-sensing organic hydrogel fiber prepared according to the preparation method of the present invention.

[0022] Application of an ultra-low detection limit strain-sensing organic hydrogel fiber prepared according to the present invention in flexible materials.

[0023] The present invention adopts the above technical solution and has the following advantages compared with the prior art:

[0024] (1) This invention employs a wet spinning process combined with a one-step freeze-thaw method to coaxially spin core-sheath structure organic hydrogel fibers. This soft template method breaks the limitations of the mold method, allowing for flexible control of fiber diameter and enabling mass production. Furthermore, based on hydrogen bonding, polyvinyl alcohol and aniline tetramer molecules rapidly crosslink to form organic hydrogel fibers. This preparation process is simple, easy to operate, and the quality of active ingredients is easily controlled, significantly superior to traditional in-situ synthesis or post-growth preparation methods.

[0025] (2) Aniline tetramers self-assemble into nanofibers with high aspect ratio and cross-link with polyvinyl alcohol to form a three-dimensional nanofiber network structure, which endows the organic hydrogel with a competitive ion conduction mechanism, making the organic hydrogel fiber have high strength and toughness, high strain sensitivity and ultra-low detection limit (0.01%). It can repeatedly obtain stable electrical signals under small strain and large strain, so it has application prospects in motion monitoring of various joints in the human body.

[0026] (3) The organic solvent added to this system plays a dual role in dissolving aniline tetramer and cross-linked polyvinyl alcohol. The prepared hydrogel fiber has excellent moisturizing and antifreeze properties, which expands the use of gel in cold and dry environments.

[0027] (4) The high elasticity organic hydrogel fiber prepared by the present invention has excellent elasticity, tensile properties, low detection limit, wide detection range, high strain sensitivity and antifreeze and moisturizing properties. Attached Figure Description

[0028] Figure 1 This is a sample image of the organic hydrogel fiber obtained in this invention.

[0029] Figure 2 This is a scanning electron microscope image of the organic hydrogel fiber obtained in Example 1 of the present invention.

[0030] Figure 3 Mechanical and elastic properties of the organic hydrogel fibers obtained in various embodiments of the present invention.

[0031] Figure 4 This is a graph showing the low detection limit sensing performance of the organic hydrogel fiber obtained in Example 2 of the present invention at room temperature.

[0032] Figure 5This is a sensitivity diagram of the organic hydrogel fiber obtained in Example 2 of the present invention at room temperature.

[0033] Figure 6 This is a low-temperature (-40℃) sensitivity diagram of the organic hydrogel fiber obtained in Example 2 of the present invention.

[0034] Figure 7 This is a sensitivity diagram of the organic hydrogel fiber obtained in Example 3 of the present invention at room temperature.

[0035] Figure 8 This is a small strain sensing signal diagram of human organs using organic hydrogel fibers in Embodiment 3 of the present invention.

[0036] Figure 9 This is a large strain sensing signal diagram of human organs using organic hydrogel fibers in Embodiment 3 of the present invention.

[0037] Figure 10 This invention relates to the monitoring of pulse rate in adult women before and after exercise using organic hydrogel fibers, as described in Example 4 of this invention.

[0038] Figure 11 This invention relates to the application of Morse code encryption and decryption for the organic hydrogel fibers in Embodiment 5 of the present invention. Detailed Implementation

[0039] A method for preparing an ultra-low detection limit strain-sensing organic hydrogel fiber includes the following steps:

[0040] Step (1): Preparation of solution A: Dissolve the polyvinyl alcohol matrix and acid solution in deionized water and store at room temperature; the polyvinyl alcohol matrix solution is an aqueous solution containing 1-20 wt% polyvinyl alcohol; the acid solution is one or more of hydrochloric acid, sulfuric acid, phosphoric acid or nitric acid solution with a concentration of 0.1-6 mol / L.

[0041] Preparation of Solution B: The aniline tetramer monomer is dissolved in an organic solvent and stored at room temperature; the organic solvent is one or more solutions selected from ethylene glycol, glycerol, pentanediol, acetone, and methanol, and the concentration of the aniline tetramer monomer dissolved in the organic solvent is 0.5–100 mg / ml;

[0042] Preparation of solution C: Sodium alginate is dissolved in deionized water to obtain a "skin" curing solution with a concentration of 1-20 wt%, which is then injected into a syringe for later use;

[0043] Step (2): Mix solution A and solution B evenly to obtain a mixed spinning solution. Inject the solution into a syringe as a "core" solution for later use.

[0044] Step (3): The above (2) and solution C are coaxially wet spun and extruded into a coagulation bath containing one or more of CaCl2, BaCl2 and AlCl3 at a concentration of 0.05 to 0.5 mol / L to obtain organic hydrogel fibers with a core-sheath structure.

[0045] Step (4): The organic hydrogel fibers prepared above are drawn into a freezing liquid (dry ice or liquid nitrogen) and frozen for 0.5 to 96 hours, and then transferred to a freezer for cross-linking reaction for 1 to 96 hours;

[0046] Step (5): After the reaction is complete, take out the frozen gel fiber and thaw it to obtain the core-skin structure organic hydrogel fiber. Then, use one or two of potassium citrate and sodium citrate at a concentration of 0.05-1.0 mol / L to dissolve the "skin" structure and obtain the core-skin structure organic hydrogel fiber.

[0047] Step (6): The "core" structure organic hydrogel fiber is immersed in an organic solvent / acid solution for 0.5 to 96 hours. After being removed, it reaches dehydration equilibrium at room temperature to obtain stretchable, elastic, and conductive organic hydrogel fiber.

[0048] An ultra-low detection limit strain-sensing organic hydrogel fiber prepared according to the preparation method of the present invention.

[0049] Application of an ultra-low detection limit strain-sensing organic hydrogel fiber prepared according to the present invention in flexible materials.

[0050] Example 1

[0051] At room temperature, 10g of polyvinyl alcohol was first dissolved in 90ml of 0.2mol / L hydrochloric acid to prepare a 10wt% polyvinyl alcohol solution, denoted as solution A. 30mg of aniline tetramer was dissolved in 5ml of ethylene glycol to obtain a 6mg / ml solution, denoted as solution B. After complete dissolution, 5ml of solution A was slowly added to solution B in the beaker and vigorously stirred for several minutes. Air bubbles were removed by sonication. The mixture was then injected into a 2ml syringe and fixed to a syringe pump for later use. 0.1g of sodium alginate was dissolved in 9.9ml of deionized water to obtain a 1wt% sodium alginate solution, which was injected into a 2ml syringe and fixed to a syringe pump for later use. The syringe pump was used to extrude the solution into a 15wt% calcium chloride solution at a rate of 1.5ml / min. After fiber formation, the solution was transferred to liquid nitrogen for freezing for 15min. After freezing, the solution was transferred to a freezer and reacted at a low temperature (-60℃) for 48h. After the reaction was complete, the hydrogel fibers were removed from the freezer and thawed for 30 minutes. After complete thawing, post-treatment was performed: the fibers were soaked in 0.5 mol / L sodium citrate solution for 48 hours to remove the "skin" structure, and then transferred to 50% ethylene glycol acidic solution (0.2 M HCl) for 48 hours. The fibers were then removed and allowed to reach dehydration equilibrium to obtain the organic hydrogel fibers. Figure 1 ). Figure 2 This is an electron microscope image of hydrogel fibers. The mechanical strength is 1.36 MPa, and the elastic deformation can reach 480%. Figure 3 ).

[0052] Example 2

[0053] At room temperature, 15g of polyvinyl alcohol was first dissolved in 85ml of 0.5mol / L sulfuric acid to prepare a 15wt% polyvinyl alcohol solution, denoted as solution A. 50mg of aniline tetramer was dissolved in 5ml of glycerol to obtain a 10mg / ml solution, denoted as solution B. After complete dissolution, 5ml of solution A was slowly added to solution B in the beaker and vigorously stirred for several minutes. Air bubbles were removed by sonication. The mixture was then injected into a 2ml syringe and fixed to a syringe pump for later use. 0.1g of sodium alginate was dissolved in 9.9ml of deionized water to obtain a 1wt% sodium alginate solution. This solution was injected into a 2ml syringe and fixed to a syringe pump for later use. The syringe pump was used to extrude the solution into a 20wt% BaCl2 solution at a rate of 2ml / min. After fiber formation, the solution was transferred to liquid nitrogen for freezing for 20min. After freezing, the solution was transferred to a freezer and reacted at a low temperature (-60℃) for 36h. After the reaction was complete, the hydrogel fibers were removed from the freezer and thawed for 30 minutes. After complete thawing, post-treatment was performed: the fibers were soaked in a 1 mol / L sodium citrate solution for 36 hours to remove the "skin" structure, and then transferred to a 50% glycerol acidic solution (0.5 M H₂SO₄) for 36 hours. The fibers were then removed to reach dehydration equilibrium, yielding the organic hydrogel fibers. The mechanical strength was 1.38 MPa, and the elastic deformation reached 643%. Figure 3 It can achieve an ultra-low detection limit of 0.01%. Figure 4 The sensitivity (GF) at 10% strain is 1.53. Figure 5 It exhibits good sensitivity at ultra-low temperatures of -40℃, with GF values ​​of 2.83, 5.87, and 9.46 for strains of 0-70%, 70-140%, and 140-200%, respectively. Figure 6 ).

[0054] Example 3

[0055] At room temperature, 10g of polyvinyl alcohol was first dissolved in 90ml of 0.5mol / L hydrochloric acid to prepare a 10wt% polyvinyl alcohol solution, denoted as solution A. 75mg of aniline tetramer was dissolved in 5ml of pentanediol to obtain a 15mg / ml solution, denoted as solution B. After complete dissolution, 5ml of solution A was slowly added to solution B in the beaker and vigorously stirred for several minutes. Air bubbles were removed by sonication. The mixture was then injected into a 2ml syringe and fixed to a syringe pump for later use. 0.5g of sodium alginate was dissolved in 9.5ml of deionized water to obtain a 5wt% sodium alginate solution. This solution was injected into a 2ml syringe and fixed to a syringe pump for later use. The syringe pump was used to extrude the solution into an AlCl3 (10wt%) solution at a rate of 2.5ml / min. After fiber formation, the solution was transferred to liquid nitrogen for freezing for 30min. After freezing, the solution was transferred to a freezer and reacted at a low temperature (-60℃) for 72h. After the reaction was complete, the hydrogel fibers were removed from the freezer and thawed for 20 minutes. After complete thawing, post-treatment was performed: the fibers were soaked in a 1 mol / L sodium citrate solution for 48 hours to remove the "skin" structure, and then transferred to a 50% pentanediol acidic solution (0.5 M HCl) for 48 hours. The fibers were then removed to reach dehydration equilibrium, yielding the organic hydrogel fibers. The mechanical strength was 1.2 MPa, and the elastic deformation reached 540%. Figure 3 ).like Figure 7 As shown, the strain values ​​(GF) at room temperature for 0-80%, 80-180%, and 180-300% are 2.70, 4.79, and 6.98, respectively. Figure 8 , 9 The sensor performance of the gel fiber under small and large strain conditions on body organs was demonstrated.

[0056] Example 4

[0057] At room temperature, 15g of polyvinyl alcohol was first dissolved in 85ml of 0.5mol / L sulfuric acid to prepare a 15wt% polyvinyl alcohol solution, denoted as solution A. 50mg of aniline tetramer was dissolved in a mixture of 4ml ethylene glycol and 1ml acetone to obtain a 10mg / ml solution in a beaker, denoted as solution B. After complete dissolution, 5ml of solution A was slowly added to solution B in the beaker and vigorously stirred for several minutes. Air bubbles were removed by sonication, and the mixture was injected into a 2ml syringe and fixed to a syringe pump for later use. 1g of sodium alginate was dissolved in 9ml of deionized water to obtain a 10wt% sodium alginate solution, which was injected into a 2ml syringe and fixed to a syringe pump for later use. The syringe pump was used to extrude the solution into a 20wt% BaCl2 solution at a rate of 3ml / min. After fiber formation, the solution was transferred to liquid nitrogen for freezing for 30min. After freezing, the solution was transferred to a freezer and reacted at a low temperature (-50℃) for 72h. After the reaction was complete, the hydrogel fibers were removed from the refrigerator and thawed for 20 minutes. After complete thawing, post-processing was performed: the fibers were soaked in a 1 mol / L potassium citrate solution for 48 hours to remove the "skin" structure, and then transferred to a 50% ethylene glycol acidic solution (0.5 M H₂SO₄) for 48 hours. The fibers were then removed to reach dehydration equilibrium, yielding the organic hydrogel fibers. Figure 10 The single fiber shown can monitor changes in pulse rate before and after exercise in adult women.

[0058] Example 5

[0059] At room temperature, 20g of polyvinyl alcohol was first dissolved in 80ml of 1mol / L sulfuric acid to prepare a 20wt% polyvinyl alcohol solution, denoted as solution A. 50mg of aniline tetramer was dissolved in a mixture of 4ml glycerol and 1ml ethanol to obtain a 10mg / ml solution, denoted as solution B. After complete dissolution, 5ml of solution A was slowly added to solution B in the beaker and vigorously stirred for several minutes. Air bubbles were removed by sonication. The mixture was then injected into a 2ml syringe and fixed to a syringe pump for later use. 0.5g of sodium alginate was dissolved in 9.5ml of deionized water to obtain a 5wt% sodium alginate solution, which was injected into a 2ml syringe and fixed to a syringe pump for later use. The syringe pump was used to extrude the solution into a BaCl2 / AlCl3 (20wt%) solution at a rate of 3ml / min. After fiber formation, the solution was transferred to liquid nitrogen for freezing for 40min. After freezing, the solution was transferred to a freezer and reacted at a low temperature (-70℃) for 48h. After the reaction was complete, the hydrogel fibers were removed from the refrigerator and thawed for 20 minutes. After complete thawing, post-processing was performed: the fibers were soaked in a 1 mol / L sodium citrate solution for 48 hours to remove the "skin" structure, and then transferred to a 50% glycerol acidic solution (0.5 M HNO3) for 48 hours. The fibers were then removed to reach dehydration equilibrium, yielding the organic hydrogel fibers. Figure 11As shown, a single fiber is fixed to the first joint of the index finger and can transmit Morse signals according to the range of joint movement.

[0060] Comparative Example 1

[0061] At room temperature, 10 g of polyvinyl alcohol was first dissolved in 90 ml of 0.2 mol / L hydrochloric acid to prepare a 10 wt% polyvinyl alcohol solution, denoted as solution A. Solution A was injected into a 2 ml syringe and fixed to a syringe pump for later use. 0.1 g of sodium alginate was dissolved in 9.9 ml of deionized water to obtain a 1 wt% sodium alginate solution, which was injected into a 2 ml syringe and fixed to a syringe pump for later use. The syringe pump was used to extrude the solution into a 15 wt% calcium chloride solution at a rate of 1.5 ml / min. After the fiber was formed, it was transferred to liquid nitrogen for freezing for 15 min. After freezing, it was transferred to a freezer for low-temperature (-60℃) reaction for 48 h. After the reaction was completed, the hydrogel fibers were removed from the freezer and thawed for 30 minutes. After complete thawing, post-treatment was performed: the fibers were soaked in 0.5 mol / L sodium citrate solution for 48 hours to remove the "skin" structure, and then transferred to 50% ethylene glycol acidic solution (0.2 M HCl) for 48 hours. The fibers were then removed to achieve dehydration equilibrium, yielding the organic hydrogel fibers. These organic hydrogel fibers exhibited a mechanical strength of 0.144 MPa, an elastic deformation of 287%, and an ultra-low detection limit of 0.01%. At room temperature, the strain coefficients (GF) at 0-100%, 100-200%, and 200-300% were 1.71, 3.12, and 5.22, respectively.

[0062] Comparative Example 2

[0063] At room temperature, 10 g of polyvinyl alcohol was first dissolved in 90 ml of 0.2 mol / L hydrochloric acid to prepare a 10 wt% polyvinyl alcohol solution, denoted as solution A. 50 mg of aniline tetramer was dissolved in 5 ml of ethylene glycol to obtain a 10 mg / ml solution in a beaker, denoted as solution B. After complete dissolution, 5 ml of solution A was slowly added to solution B in the beaker and vigorously stirred for several minutes. Air bubbles were removed by sonication to obtain the spinning solution. The solution was injected into a fiber mold, and the mold was then transferred to liquid nitrogen and frozen for 8 hours. After removal, it was thawed at -10℃ for 24 hours to demold the organic hydrogel fiber. The organic hydrogel fiber has a mechanical strength of 1.6 MPa, an elastic deformation of 800%, and GF values ​​of 2.16, 3.90, and 5.77 at room temperature strains of 0-70%, 70-180%, and 180-300%, respectively. The limit of detection is 1%.

[0064] The present invention has been described in detail with reference to the accompanying drawings. However, those skilled in the art should understand that the above embodiments are only preferred embodiments of the present invention. The detailed description is only to help readers better understand the spirit of the present invention, and is not intended to limit the scope of protection of the present invention. On the contrary, any improvement or modification made based on the inventive spirit of the present invention should fall within the scope of protection of the present invention.

Claims

1. A method for preparing an ultra-low detection limit strain-sensing organic hydrogel fiber, characterized in that... Includes the following steps: Step (1): Prepare solution A: Dissolve the polyvinyl alcohol matrix and acid solution in deionized water and store at room temperature; Prepare solution B: Dissolve the aniline tetramer monomer in an organic solvent and store at room temperature; Prepare solution C: Dissolve sodium alginate in deionized water to obtain the solution for "skin" curing, and inject it into a syringe for later use; Step (2): Mix solution A and solution B evenly to obtain a mixed spinning solution. Inject the solution into a syringe as a "core" solution for later use. Step (3): The product obtained in step (2) is coaxially wet-spun with solution C and extruded into a coagulation bath containing non-oxidizing divalent and trivalent metal salts to obtain organic hydrogel fibers with a core-sheath structure. Step (4): The organic hydrogel fibers prepared in step (3) above are drawn into the freezing liquid and frozen, and then transferred to a freezer for cross-linking reaction; Step (5): After the reaction is complete, the frozen gel fiber is taken out and thawed to obtain the core-skin structure organic hydrogel fiber. The "skin" structure is dissolved by citrate to obtain the "core" structure organic hydrogel fiber. Step (6): The "core" structure organic hydrogel fiber is immersed in an organic solvent / acid solution for several hours. After being taken out, it reaches dehydration equilibrium at room temperature to obtain an organic hydrogel fiber with an ultra-low detection limit of 0.01% for strain sensing.

2. The preparation method according to claim 1, characterized in that: The polyvinyl alcohol matrix solution in step (1) is an aqueous solution containing 1-20 wt% polyvinyl alcohol; the acid solution is one or more of hydrochloric acid, sulfuric acid, phosphoric acid or nitric acid solutions with a concentration of 0.1-6 mol / L.

3. The preparation method according to claim 1, characterized in that: The organic solvent in step (1) is one or more solutions of ethylene glycol, glycerol, pentanediol, acetone, and methanol, and the concentration of the aniline tetramer monomer dissolved in the organic solvent is 0.5 to 100 mg / ml.

4. The preparation method according to claim 1, characterized in that: In step (1), the sodium alginate solution is an aqueous solution containing 1 to 40 wt% sodium alginate.

5. The preparation method according to claim 1, characterized in that: The non-oxidizing divalent and trivalent metal salts in step (3) are one or more of CaCl2, BaCl2 and AlCl3, with a concentration of 0.05 to 0.5 mol / L.

6. The preparation method according to claim 1, characterized in that: In step (4), the cross-linking reaction time in the freezing liquid is 0.5 to 96 hours; the freezer thawing temperature is -80 to 25°C, and the time is 1 to 96 hours.

7. The preparation method according to claim 1, characterized in that: The citrate in step (5) is one or both of potassium citrate and sodium citrate, and its concentration is 0.05 to 1.0 mol / L.

8. The preparation method according to claim 1, characterized in that: The organic solvent / acid solution in step (6) is one or more of ethylene glycol, glycerol, pentanediol, acetone, methanol / hydrochloric acid, sulfuric acid, phosphoric acid, or nitric acid; the soaking time is 0.5 to 96 hours.

9. A polyvinyl alcohol-aniline tetramer organic hydrogel fiber prepared according to any one of claims 1-8.

10. The application of a polyvinyl alcohol-aniline tetramer organic hydrogel fiber prepared by the preparation method according to any one of claims 1-8 in flexible materials.

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