A polyvinyl alcohol-aniline tetramer organic hydrogel fiber, its preparation method and application

Abstract

A polyvinyl alcohol-aniline tetramer organic hydrogel fiber, its preparation method and application, including injecting a water / organic mixed solution of polyvinyl alcohol and aniline tetramer into a fiber mold, then placing the mold in a cryogenic fluid (dry ice or liquid nitrogen) for freeze crystallization cross-linking, and transferring it to a freezer for thawing after a period of time, and finally demolding to obtain the polyvinyl alcohol-aniline tetramer organic hydrogel fiber. The organic hydrogel fiber prepared in this way has high mechanical strength, excellent stretchability, good conductivity, moisture retention rate, frost resistance and good strain sensitivity, and can stably output the deformation signal during human movement. The preparation process of this organic hydrogel is simple, low-cost and has excellent performance, showing great application potential in the field of wearable strain sensors.

Description

Technical Field

[0001] The present invention belongs to the technical field of materials for flexible wearable electronic devices, and particularly relates to a polyvinyl alcohol-aniline tetramer organic hydrogel fiber, a preparation method thereof, and an application thereof. Background Art

[0002] Hydrogel is a new type of soft material with water as the matrix, which is cross-linked by chemical or physical actions. Hydrogels are soft, stretchable, and biocompatible, and are considered as one of the candidate carriers for next-generation wearable devices, having potential application values in wearable sensing, energy storage devices, biomedical detection devices, etc. The weavability of fibrous hydrogels gives them unique advantages in wearable devices, such as good integration with clothing and excellent breathability. Therefore, developing flexible and stretchable elastic sensing hydrogel fibers is of great significance.

[0003] To improve the electrical conductivity and sensitivity of hydrogels, conductive polymers such as polyaniline, polypyrrole, poly(3,4-ethylenedioxythiophene):polystyrene sulfonate, etc. are often used to prepare composite hydrogels with both ionic and electronic conduction mechanisms. However, due to the characteristics of polypyrrole and polyaniline being insoluble and infusible, the construction of conductive composite hydrogels often involves in-situ or post-growth processes, which complicates the process flow. Moreover, due to the limit of the amount of active substances, it is difficult for hydrogels to have high elasticity, electrical conductivity, mechanical properties, sensitivity, and antifreeze and moisture retention properties at the same time. In addition, hydrogels have problems such as easy evaporation of water and easy freezing at low temperatures, which limit their applications in cold and dry environments. The preparation process of existing conductive polymer-based hydrogel fibers is cumbersome and it is difficult to have high strength and toughness, high strain sensitivity, excellent moisture retention, and antifreeze properties at the same time. Summary of the Invention

[0004] The purpose of the present invention is to provide a high-strength and tough, highly conductive, highly strain-sensitive, antifreeze and moisture-retaining polyvinyl alcohol-aniline tetramer organic hydrogel fiber, a preparation method thereof, and an application thereof.

[0005] A preparation method of a polyvinyl alcohol-aniline tetramer organic hydrogel fiber includes the following steps:

[0006] Step (1): Prepare solution A: Dissolve a polyvinyl alcohol matrix and an acid solution in deionized water and store at room temperature; Prepare solution B: Dissolve an aniline tetramer monomer in an organic solvent and store at room temperature;

[0007] Step (2): Mix solution A and solution B and stir evenly to obtain a mixed stock solution, and inject the stock solution into a fiber mold to obtain an unformed hydrogel fiber;

[0008] Step (3): Place the mold containing the unformed hydrogel fiber in a cryogenic liquid for crystallization cross-linking.

[0009] Step (4): Place the mold that has been frozen for a certain time at a certain temperature for thawing. After a certain time, remove the mold to obtain the organic hydrogel fiber.

[0010] Preferably, the polyvinyl alcohol matrix solution in step (1) of the present invention is an aqueous solution containing 1-20 wt% of polyvinyl alcohol.

[0011] 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 solutions with a concentration of 0.1-6 mol / L.

[0012] Preferably, the organic solvent in step (1) of the present invention is one or more of ethylene glycol, glycerol, pentanediol, acetone, methanol, and the concentration of aniline tetramer monomer dissolved in the organic solvent is 0.5-100 mg / ml.

[0013] Preferably, the cross-linking reaction time of the mold containing the unformed hydrogel fiber in step (3) of the present invention in the freezing liquid is 0.5-96 h.

[0014] Preferably, the thawing temperature in step (4) of the present invention is -80-25°C, and the time is 1-96 h.

[0015] A polyvinyl alcohol-aniline tetramer organic hydrogel fiber prepared by the preparation method according to the present invention.

[0016] An application of a polyvinyl alcohol-aniline tetramer organic hydrogel fiber prepared by the preparation method according to the present invention in flexible materials.

[0017] The present invention adopts the above technical solutions, and compared with the prior art, has the following advantages:

[0018] (1) The present invention adopts a one-step freezing-thawing method. Based on hydrogen bond action, polyvinyl alcohol and aniline tetramer molecules are quickly cross-linked to form organic hydrogel fibers. The preparation process is simple, easy to operate, and the amount of active substances is easy to control, which is significantly better than the traditional in-situ synthesis or post-growth preparation methods.

[0019] (2) The addition of aniline tetramer endows the hydrogel with a dual conductive mechanism of electrons and ions. The competitive proton capture by aniline tetramer makes the organic hydrogel fiber have high sensitivity and can repeatedly obtain stable electrical signals under small and large strains. Therefore, it has application prospects in the motion monitoring of human joints.

[0020] (3) The organic solvent added to this system plays a dual role of dissolving aniline tetramer and cross-linking polyvinyl alcohol. The prepared hydrogel fiber has excellent moisture retention and frost resistance, expanding the use of the gel in cold and dry environments.

[0021] (4) The highly elastic organic hydrogel fiber prepared by the present invention has excellent elasticity, stretchability, strain sensitivity, and antifreeze and moisture retention properties. Description of the Drawings

[0022] Figure 1 It is a sample diagram of the hydrogel fiber obtained by the present invention.

[0023] Figure 2 It is a comparison diagram of the electrical conductivity of the hydrogel fibers obtained in each embodiment of the present invention.

[0024] Figure 3 It is a diagram of the antifreeze property of the hydrogel fiber obtained in Example 3

[0025] Figure 4 It is a comparison diagram of the moisture retention properties of the hydrogel fibers obtained in each embodiment of the present invention.

[0026] Figure 5 It is a scanning electron microscope picture of the hydrogel fiber obtained in Example 1.

[0027] Figure 6 It is a diagram of the mechanical and elastic properties of the hydrogel fibers obtained in each embodiment of the present invention.

[0028] Figure 7 It is a diagram of the sensitivity of the hydrogel fiber obtained in Example 1. Detailed Embodiments

[0029] A preparation method of a polyvinyl alcohol - aniline tetramer organic hydrogel fiber includes the following steps:

[0030] Step (1): Prepare Solution A: Dissolve the polyvinyl alcohol matrix and the acid solution in deionized water and store at room temperature; the polyvinyl alcohol matrix solution is an aqueous solution containing 1 - 20 wt% of polyvinyl alcohol; the acid solution is one or more of 0.1 - 6 mol / L hydrochloric acid, sulfuric acid, phosphoric acid, or nitric acid solution;

[0031] Prepare Solution B: Dissolve the aniline tetramer monomer in an organic solvent and store at room temperature; the organic solvent is one or more of 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;

[0032] Step (2): Mix Solution A and Solution B and stir evenly to obtain a mixed stock solution, and inject the stock solution into a fiber mold to obtain an unformed hydrogel fiber;

[0033] Step (3): Place the mold containing the unformed hydrogel fiber in a cryogenic liquid for crystallization crosslinking; the crosslinking reaction time is 0.5 - 96 h;

[0034] Step (4): Place the mold that has been frozen for a certain time at a certain temperature for thawing. After a certain time, remove the mold to obtain the organic hydrogel fiber; the thawing temperature is -80 to 25 °C, and the time is 1 to 96 h.

[0035] A polyvinyl alcohol-aniline tetramer organic hydrogel fiber prepared by the preparation method according to the present invention.

[0036] An application of a polyvinyl alcohol-aniline tetramer organic hydrogel fiber prepared by the preparation method according to the present invention in flexible materials.

[0037] Example 1

[0038] At room temperature, first dissolve 10 g of polyvinyl alcohol in 90 ml of 0.2 mol / L hydrochloric acid to prepare a 10 wt% polyvinyl alcohol solution, denoted as solution A. Take 30 mg of aniline tetramer and dissolve it in 5 ml of ethylene glycol to obtain a 6 mg / ml solution in a beaker, denoted as solution B. After complete dissolution, take 5 ml of solution A and slowly add it to solution B in the beaker and stir vigorously for several minutes. Ultrasonically remove the bubbles to obtain a mixed solution. Inject the mixed solution into a fiber mold, then transfer the mold to liquid nitrogen for freezing for 8 hours. After taking it out, thaw it at room temperature for 24 hours and demold to obtain the organic hydrogel fiber. After its water loss reaches equilibrium, a highly elastic and stretchable organic ion hydrogel fiber is obtained, as Figure 1 shown. The moisture retention is as Figure 4 shown. At 30 o °C room temperature for 24 h, the water content can be maintained above 79%. Figure 5 is the electron microscope photograph of the hydrogel fiber. As Figure 6 shown, the hydrogel fiber obtained after thawing at room temperature for 24 hours has a mechanical strength of 3.2 MPa and an elastic deformation of up to 1050%.

[0039] Example 2

[0040] At room temperature, first dissolve 10 g of polyvinyl alcohol in 90 ml of 0.2 mol / L hydrochloric acid to prepare a 5 wt% PVA solution, denoted as solution A. Take 75 mg of aniline tetramer and dissolve it in 5 ml of glycerol to obtain a 15 mg / ml solution in a beaker, denoted as solution B. After complete dissolution, take 5 ml of solution A and slowly add it to solution B in the beaker and stir vigorously for several minutes. Ultrasonically remove the bubbles to obtain the spinning dope. Inject the dope into a fiber mold, then transfer the mold to liquid nitrogen for freezing for 8 hours. After taking it out, thaw it at -10 °C for 24 hours and demold to obtain the organic ion hydrogel fiber. After its water loss reaches equilibrium, a highly elastic and stretchable organic ion hydrogel fiber is obtained. As Figure 2 shown, the conductivity can reach 5.6 mS / cm. The moisture retention is as Figure 4As shown, the water content is 82% after thawing at -10°C for 24 hours. As Figure 6 shown, the hydrogel fiber obtained after thawing at -10°C for 24 hours has a mechanical strength of 2.0 MPa and an elastic deformation of up to 880%.

[0041] Example 3

[0042] At room temperature, first dissolve 10 g of polyvinyl alcohol in 90 ml of 0.2 mol / L hydrochloric acid to prepare a 15 wt% PVA solution, denoted as solution A. Take 50 mg of aniline tetramer and dissolve it in 5 ml of pentanediol to obtain a 10 mg / ml solution in a beaker, denoted as solution B. After complete dissolution, take 5 ml of solution A and slowly add it to solution B in the beaker and stir vigorously for a few minutes, then ultrasonically remove the bubbles to obtain a spinning dope. Inject the dope into a fiber mold, then transfer the mold to liquid nitrogen and freeze for 8 hours. After taking it out, thaw at -60°C for 48 hours and demold to obtain an organic ionic hydrogel fiber. After reaching water loss equilibrium, a highly elastic and stretchable organic ionic hydrogel fiber is obtained. The conductivity can reach 5.7 mS / cm, as Figure 2 shown. The frost resistance is as Figure 3 shown. As Figure 6 shown, the mechanical strength is 1.9 MPa and the elastic deformation can reach 930% after thawing at -60°C for 48 hours. Figure 7 shown, the sensitivity GF in the strain range of 0 - 300% can reach 3.66.

Claims

1. A preparation method of polyvinyl alcohol-aniline tetramer organic hydrogel fiber, characterized in that it comprises the following steps: Step (1): Prepare solution A: Dissolve the polyvinyl alcohol matrix and the 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; wherein the polyvinyl alcohol matrix solution is an aqueous solution containing 1-20 wt% of 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; the organic solvent is one or more of ethylene glycol, glycerol, pentanediol, acetone, methanol, and the concentration of the aniline tetramer monomer dissolved in the organic solvent is 0.5-100 mg / ml; Step (2): Mix solution A and solution B and stir evenly to obtain a mixed stock solution, and inject the stock solution into a fiber mold to obtain an unformed hydrogel fiber; Step (3): Place the mold containing the unformed hydrogel fiber in a cryogenic liquid for crystallization cross-linking; Step (4): Place the mold after freezing for a certain time at a certain temperature for thawing, and remove the mold after a certain time to obtain the organic hydrogel fiber.

2. The preparation method according to claim 1, characterized in that: in step (3), the cross-linking reaction time of the mold containing the unformed hydrogel fiber in the cryogenic liquid is 0.5-96 h.

3. The preparation method according to claim 1, characterized in that: the thawing temperature in step (4) is -80-25 °C and the time is 1-96 h.

4. A polyvinyl alcohol-aniline tetramer organic hydrogel fiber prepared by the preparation method according to claim 1.

5. An application of a polyvinyl alcohol-aniline tetramer organic hydrogel fiber prepared by the preparation method according to claim 1 in flexible materials.

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