Anti-freezing hydrogel for flexible wearable device and preparation method and application thereof

Abstract

The application discloses a preparation method of anti-freezing hydrogel for flexible wearable devices and relates to the technical field of hydrogel. The method comprises the following steps: S1, adding acid-doped polyaniline into a mixed solution and uniformly mixing to obtain a polyaniline solution; S2, adding polyvinyl alcohol into the polyaniline solution and stirring to fully dissolve the polyvinyl alcohol, so as to obtain a mixed solution; and S3, first placing the mixed solution in a refrigerator to freeze, then taking out the mixed solution, and thawing at room temperature, so as to obtain the anti-freezing hydrogel. The hydrogel prepared by the method is non-toxic and harmless, has good electrical activity, compatibility and biodegradability, has good mechanical properties, and has a breaking elongation rate of up to 180%; the specific capacitance value C is up to 6.26 F / g; the hydrogel can be applied to wearable electronic devices, has a significant application prospect and other functionalization potential.

Description

Technical Field

[0001] This invention relates to the field of hydrogel technology, specifically to an antifreeze hydrogel for flexible wearable devices, its preparation method, and its application. Background Technology

[0002] Hydrogels are a class of highly hydrophilic three-dimensional network gels that swell rapidly in water and retain a large volume of water without dissolving in this swollen state. In recent years, portable, wearable electronic devices, such as electronic skin, have gradually emerged with the development of electronic information technology. Researchers have paid extensive attention to the excellent mechanical properties, biocompatibility, and conductivity of hydrogels. However, traditional hydrogels freeze below 0°C, thus losing their inherent elasticity and conductivity. Furthermore, most hydrogels utilize acrylamide, acrylic acid, and other materials unsuitable for direct contact with the human body as monomers, severely limiting the development of hydrogels.

[0003] Therefore, providing a non-toxic, harmless hydrogel with good electroactivity, compatibility, and biodegradability has become an important research topic. Summary of the Invention

[0004] The present invention provides an antifreeze hydrogel for flexible wearable devices, its preparation method and application, aiming to solve the problems existing in the above-mentioned background art.

[0005] To achieve the above-mentioned technical objectives, the present invention mainly adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a method for preparing an antifreeze hydrogel for flexible wearable devices, characterized by comprising the following steps:

[0007] S1 Adds acid-doped polyaniline to the mixed solution and mixes it evenly to obtain a polyaniline solution;

[0008] S2. Polyvinyl alcohol is added to the polyaniline solution and stirred until it is fully dissolved to obtain a mixed solution;

[0009] S3 First, place the mixed solution in a refrigerator to freeze, then take it out and thaw it at room temperature to obtain an antifreeze hydrogel.

[0010] In a preferred embodiment of the present invention, the acid-doped polyaniline powder is phytic acid-doped polyaniline powder.

[0011] Furthermore, the preparation method of the phytic acid-doped polyaniline includes the following steps:

[0012] S11 Dissolves ammonium persulfate thoroughly in distilled water and then cools it to 4°C in a refrigerator to obtain mixed solution A;

[0013] S12 mixes distilled water, phytic acid and aniline evenly and then cools it in a refrigerator to 4°C to obtain mixed solution B;

[0014] S13 Mix solution A and solution B evenly, place in a freezer for refrigeration for no less than 12 hours, and obtain phytic acid-doped polyaniline.

[0015] Furthermore, the method for preparing phytic acid-doped polyaniline also includes a post-processing step:

[0016] S14 The crude phytic acid-doped polyaniline obtained in S13 is filtered, washed, and then dried in an oven to obtain the refined phytic acid-doped polyaniline.

[0017] In some embodiments of the present invention, the mixed solution is a mixed solution composed of deionized water and ethylene glycol, wherein the volume ratio of deionized water to ethylene glycol is 1:1.

[0018] In some embodiments of the present invention, in step S1, the mass-to-volume ratio (g / ml) of the acid-doped polyaniline to the mixed solution is 1:1-5.

[0019] Furthermore, in step S2, the amount of polyvinyl alcohol added is 10-50 times the mass of the acid-doped polyaniline.

[0020] Furthermore, in step S1, the mass-to-volume ratio (g / ml) of the acid-doped polyaniline to the mixed solution is 1:1, and in step S2, the amount of polyvinyl alcohol added is 50 times the mass of the acid-doped polyaniline.

[0021] Secondly, the present invention also provides an antifreeze hydrogel prepared by the above-described preparation method.

[0022] Thirdly, the present invention also provides the application of the antifreeze hydrogel of the second aspect in the preparation of flexible wearable electronic devices.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The hydrogel prepared by this method is non-toxic, harmless, and has good electroactivity, compatibility, and biodegradability;

[0025] 2. The phytic acid-doped polyaniline gel prepared by this method has good mechanical properties, and its elongation at break can reach up to 180%.

[0026] 3. The hydrogel prepared by this method has a specific capacitance value C as high as 6.26 F / g;

[0027] 4. The hydrogel prepared by this invention can be applied to wearable electronic devices, and has significant application prospects and potential for other functionalizations. Attached Figure Description

[0028] Figure 1 A diagram of phytic acid-doped polyaniline powder provided in the application embodiments;

[0029] Figure 2 A diagram of hydrochloric acid-doped polyaniline powder provided in the embodiments of this application;

[0030] Figure 3 A diagram of dedoped polyaniline powder provided in the embodiments of this application;

[0031] Figure 4 This is a gel image of the antifreeze PVA / PANI prepared in Example 1 of this application;

[0032] Figure 5 The infrared spectrum of the antifreeze PVA / PANI gel prepared in Example 1 of this application is shown.

[0033] Figure 6 This is a schematic diagram of the mechanical properties of the antifreeze PVA / PANI gel prepared in Example 1 of this application; wherein, (a) the hydrogel lifts a 200g weight; (bd) the hydrogel resists glass rod penetration; (e) various deformations and stretching of the hydrogel;

[0034] Figure 7 The diagram shows the effect of stretching and knotting of antifreeze PVA / PANI gels with polyaniline contents of 5mg, 10mg, 15mg, 20mg, and 25mg on the illumination of LED lights, provided for embodiments of this application.

[0035] Figure 8 Cyclic voltammetry curves of different PANI contents at a scan rate of 5 mV / s are provided for embodiments of this application.

[0036] Figure 9 Cyclic voltammetry curves at different scan rates when the PANI content is 5 mg, as provided in the embodiments of this application;

[0037] Figure 10 Impedance spectral analysis diagram of PANI content of 5 mg provided in the embodiments of this application;

[0038] Figure 11 Finger bending test image of the antifreeze PVA / PANI gel prepared in Example 1 of this application;

[0039] Figure 12 Tensile test diagram of the antifreeze PVA / PANI gel prepared in Example 1 of this application. Detailed Implementation

[0040] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0041] I. Experimental Materials and Reagents

[0042] The experimental materials and reagents used in this experiment are listed in Table 1.

[0043] Table 1 Experimental Materials and Reagents

[0044]

[0045] II. Experimental Instruments and Equipment

[0046] The experimental instruments and equipment used in this experiment are listed in Table 2.

[0047] Table 2 Experimental Instruments and Equipment

[0048]

[0049]

[0050] III. Experimental Formula

[0051] The experimental formula used in this experiment is shown in Table 3.

[0052] Table 3 Experimental formulation

[0053]

[0054] Example 1

[0055] (1) Preparation of phytic acid-doped polyaniline

[0056] Weigh 0.286 g of ammonium persulfate into bottle A, add 1 ml of distilled water to dissolve it completely, and then cool it to 4°C in a refrigerator. Measure 2 ml of distilled water into bottle B, and add 920 μL of phytic acid and 375 μL of aniline sequentially using a pipette. Stir with a magnetic stirrer until the solution is homogeneous, and then cool it to 4°C in a refrigerator. Combine the solutions from bottles A and B and refrigerate for at least 12 hours. Then filter using a vacuum pump, wash three times with ethanol, and twice with deionized water to obtain a powder. Finally, dry the powder in an oven at 50°C for 2 hours and store it in a sealed bag. Figure 1 )

[0057] (2) Preparation of antifreeze PVA / PANI gel

[0058] First, measure 2.5 ml of deionized water and 2.5 ml of ethylene glycol and mix them. Then, weigh 5 mg of phytic acid-doped polyaniline powder and add it to the mixed solution. Disperse the powder ultrasonically in an ultrasonic cleaner (set the temperature to 50℃) until it is fully dissolved, obtaining a homogeneous polyaniline solution. Weigh 0.25 g of polyvinyl alcohol and add it to the polyaniline solution. Stir using a thermostatic magnetic stirrer at 85℃ for 2 hours (600 r / min) to ensure complete dissolution, obtaining a mixed solution. Freeze the solution in a refrigerator for 30 minutes, then thaw it at room temperature for 24 hours. The resulting antifreeze PVA / PANI gel was then tested for its mechanical and electrochemical properties. Figure 2-4 As shown, this is the prepared antifreeze PVA / PANI gel.

[0059] Example 2

[0060] (1) Preparation of phytic acid-doped polyaniline

[0061] Weigh 0.286 g of ammonium persulfate into bottle A, add 1 ml of distilled water to dissolve it completely, and then cool it to 4°C in a refrigerator. Measure 2 ml of distilled water into bottle B, and add 920 μL of phytic acid and 375 μL of aniline sequentially using a pipette. Stir with a magnetic stirrer until the solution is homogeneous, and then cool it to 4°C in a refrigerator. Combine the solutions from bottles A and B and refrigerate for at least 12 hours. Then filter using a vacuum pump, wash three times with ethanol, and twice with deionized water to obtain a powder. Finally, dry the powder in an oven at 50°C for 2 hours and store it in a sealed bag. Figure 1 )

[0062] (2) Preparation of antifreeze PVA / PANI gel

[0063] First, 2.5 ml of deionized water and 2.5 ml of ethylene glycol were measured and mixed. Then, 10 mg of phytic acid-doped polyaniline powder was weighed and added to the mixed solution. The mixture was ultrasonically dispersed in an ultrasonic cleaner (set to 50°C) until fully dissolved, resulting in a homogeneous polyaniline solution. 0.25 g of polyvinyl alcohol was weighed and added to the polyaniline solution, and stirred at 85°C for 2 hours (600 r / min) using a thermostatic magnetic stirrer to ensure complete dissolution, obtaining a mixed solution. The solution was then frozen in a refrigerator for 30 minutes and thawed at room temperature for 24 hours. The resulting antifreeze PVA / PANI gel was then tested for its mechanical and electrochemical properties.

[0064] Example 3

[0065] (1) Preparation of phytic acid-doped polyaniline

[0066] Weigh 0.286 g of ammonium persulfate into bottle A, add 1 ml of distilled water to dissolve it completely, and then cool it to 4°C in a refrigerator. Measure 2 ml of distilled water into bottle B, and add 920 μL of phytic acid and 375 μL of aniline sequentially using a pipette. Stir with a magnetic stirrer until the solution is homogeneous, and then cool it to 4°C in a refrigerator. Combine the solutions from bottles A and B and refrigerate for at least 12 hours. Then filter using a vacuum pump, wash three times with ethanol, and twice with deionized water to obtain a powder. Finally, dry the powder in an oven at 50°C for 2 hours and store it in a sealed bag. Figure 1 )

[0067] (2) Preparation of antifreeze PVA / PANI gel

[0068] First, 2.5 ml of deionized water and 2.5 ml of ethylene glycol were measured and mixed. Then, 15 mg of phytic acid-doped polyaniline powder was weighed and added to the mixed solution. The mixture was ultrasonically dispersed in an ultrasonic cleaner (set to 50°C) until fully dissolved, resulting in a homogeneous polyaniline solution. 0.25 g of polyvinyl alcohol was weighed and added to the polyaniline solution, and stirred at 85°C for 2 hours (600 r / min) using a thermostatic magnetic stirrer to ensure complete dissolution, obtaining a mixed solution. The solution was then frozen in a refrigerator for 30 minutes and thawed at room temperature for 24 hours. The resulting antifreeze PVA / PANI gel was then tested for its mechanical and electrochemical properties.

[0069] Example 4

[0070] (1) Preparation of phytic acid-doped polyaniline

[0071] Weigh 0.286 g of ammonium persulfate into bottle A, add 1 ml of distilled water to dissolve it completely, and then cool it to 4°C in a refrigerator. Measure 2 ml of distilled water into bottle B, and add 920 μL of phytic acid and 375 μL of aniline sequentially using a pipette. Stir with a magnetic stirrer until the solution is homogeneous, and then cool it to 4°C in a refrigerator. Combine the solutions from bottles A and B and refrigerate for at least 12 hours. Then filter using a vacuum pump, wash three times with ethanol, and twice with deionized water to obtain a powder. Finally, dry the powder in an oven at 50°C for 2 hours and store it in a sealed bag. Figure 1 )

[0072] (2) Preparation of antifreeze PVA / PANI gel

[0073] First, 2.5 ml of deionized water and 2.5 ml of ethylene glycol were measured and mixed. Then, 20 mg of phytic acid-doped polyaniline powder was weighed and added to the mixed solution. The mixture was ultrasonically dispersed in an ultrasonic cleaner (set to 50°C) until fully dissolved, resulting in a homogeneous polyaniline solution. 0.25 g of polyvinyl alcohol was weighed and added to the polyaniline solution, and stirred at 85°C for 2 hours (600 r / min) using a thermostatic magnetic stirrer to ensure complete dissolution, obtaining a mixed solution. The solution was then frozen in a refrigerator for 30 minutes and thawed at room temperature for 24 hours. The resulting antifreeze PVA / PANI gel was then tested for its mechanical and electrochemical properties.

[0074] Example 5

[0075] (1) Preparation of phytic acid-doped polyaniline

[0076] Weigh 0.286 g of ammonium persulfate into bottle A, add 1 ml of distilled water to dissolve it completely, and then cool it to 4°C in a refrigerator. Measure 2 ml of distilled water into bottle B, and add 920 μL of phytic acid and 375 μL of aniline sequentially using a pipette. Stir with a magnetic stirrer until the solution is homogeneous, and then cool it to 4°C in a refrigerator. Combine the solutions from bottles A and B and refrigerate for at least 12 hours. Then filter using a vacuum pump, wash three times with ethanol, and twice with deionized water to obtain a powder. Finally, dry the powder in an oven at 50°C for 2 hours and store it in a sealed bag. Figure 1 )

[0077] (2) Preparation of antifreeze PVA / PANI gel

[0078] First, 2.5 ml of deionized water and 2.5 ml of ethylene glycol were measured and mixed. Then, 25 mg of phytic acid-doped polyaniline powder was weighed and added to the mixed solution. The mixture was ultrasonically dispersed in an ultrasonic cleaner (set to 50°C) until fully dissolved, resulting in a homogeneous polyaniline solution. 0.25 g of polyvinyl alcohol was weighed and added to the polyaniline solution, and stirred at 85°C for 2 hours (600 r / min) using a thermostatic magnetic stirrer to ensure complete dissolution, obtaining a mixed solution. The solution was then frozen in a refrigerator for 30 minutes and thawed at room temperature for 24 hours. The resulting antifreeze PVA / PANI gel was then tested for its mechanical and electrochemical properties.

[0079] Comparative Example 1

[0080] Preparation of hydrochloric acid-doped polyaniline: 137.5 ml of distilled water was added to 12.5 ml of hydrochloric acid to prepare a 1M hydrochloric acid solution. 1.64 ml of aniline was measured in bottle A, and then 50 ml of the 1M hydrochloric acid solution was added. 4.108 g of ammonium persulfate was weighed in bottle B, and then 20 ml of the 1M hydrochloric acid solution was added. Solution B was quickly added to solution A, and the mixture was stirred vigorously for 10 seconds. The mixture was then allowed to stand at 15°C for 15 hours. The washing and filtration steps to obtain the powder were the same as those for phytic acid-doped polyaniline. (e.g.) Figure 2 )

[0081] Comparative Example 2

[0082] Preparation of dedoped polyaniline: 100 ml of 33% ammonia solution was measured into a beaker, and then a certain amount of phytic acid-doped polyaniline powder was added. The mixture was stirred continuously with a magnetic stirrer for 24 hours. After stirring, the powder was washed with water and filtered to obtain a dry powder. (e.g.) Figure 3 )

[0083] Comparative Example 3

[0084] (1) Preparation of phytic acid-doped polyaniline

[0085] Weigh 0.286 g of ammonium persulfate into bottle A, add 1 ml of distilled water to dissolve it completely, and then cool it to 4°C in a refrigerator. Measure 2 ml of distilled water into bottle B, and add 920 μL of phytic acid and 375 μL of aniline sequentially using a pipette. Stir with a magnetic stirrer until the solution is homogeneous, and then cool it to 4°C in a refrigerator. Combine the solutions from bottles A and B and refrigerate for at least 12 hours. Then filter using a vacuum pump, wash three times with ethanol, and twice with deionized water to obtain a powder. Finally, dry the powder in an oven at 50°C for 2 hours and store it in a sealed bag. Figure 1 )

[0086] (2) Preparation of antifreeze PVA / PANI gel

[0087] First, 2.5 ml of deionized water and 0.5 ml of ethylene glycol were measured and mixed. Then, 5 mg of phytic acid-doped polyaniline powder was weighed and added to the mixed solution. The mixture was ultrasonically dispersed in an ultrasonic cleaner (set to 50°C) until fully dissolved, resulting in a homogeneous polyaniline solution. 0.25 g of polyvinyl alcohol was weighed and added to the polyaniline solution, and stirred at 85°C for 2 hours (600 r / min) using a thermostatic magnetic stirrer to ensure complete dissolution, obtaining a mixed solution. The solution was then frozen in a refrigerator for 30 minutes and thawed at room temperature for 24 hours. The resulting antifreeze PVA / PANI gel was then tested for its mechanical and electrochemical properties.

[0088] Comparative Example 4

[0089] (1) Preparation of phytic acid-doped polyaniline

[0090] Weigh 0.286 g of ammonium persulfate into bottle A, add 1 ml of distilled water to dissolve it completely, and then cool it to 4°C in a refrigerator. Measure 2 ml of distilled water into bottle B, and add 920 μL of phytic acid and 375 μL of aniline sequentially using a pipette. Stir with a magnetic stirrer until the solution is homogeneous, and then cool it to 4°C in a refrigerator. Combine the solutions from bottles A and B and refrigerate for at least 12 hours. Then filter using a vacuum pump, wash three times with ethanol, and twice with deionized water to obtain a powder. Finally, dry the powder in an oven at 50°C for 2 hours and store it in a sealed bag. Figure 1 )

[0091] (2) Preparation of antifreeze PVA / PANI gel

[0092] First, 2.5 ml of deionized water and 1.5 ml of ethylene glycol were measured and mixed. Then, 5 mg of phytic acid-doped polyaniline powder was weighed and added to the mixed solution. The mixture was ultrasonically dispersed in an ultrasonic cleaner (set to 50°C) until fully dissolved, resulting in a homogeneous polyaniline solution. 0.25 g of polyvinyl alcohol was weighed and added to the polyaniline solution, and stirred at 85°C for 2 hours (600 r / min) using a thermostatic magnetic stirrer to ensure complete dissolution, obtaining a mixed solution. The solution was then frozen in a refrigerator for 30 minutes and thawed at room temperature for 24 hours. An antifreeze PVA / PANI gel was obtained, and its mechanical and electrochemical properties were tested. Figure 4 As shown, this is the prepared antifreeze PVA / PANI gel.

[0093] Comparative Example 5

[0094] (1) Preparation of phytic acid-doped polyaniline

[0095] Weigh 0.286 g of ammonium persulfate into bottle A, add 1 ml of distilled water to dissolve it completely, and then cool it to 4°C in a refrigerator. Measure 2 ml of distilled water into bottle B, and add 920 μL of phytic acid and 375 μL of aniline sequentially using a pipette. Stir with a magnetic stirrer until the solution is homogeneous, and then cool it to 4°C in a refrigerator. Combine the solutions from bottles A and B and refrigerate for at least 12 hours. Then filter using a vacuum pump, wash three times with ethanol, and twice with deionized water to obtain a powder. Finally, dry the powder in an oven at 50°C for 2 hours and store it in a sealed bag. Figure 1 )

[0096] (2) Preparation of antifreeze PVA / PANI gel

[0097] First, 2.5 ml of deionized water and 5 ml of ethylene glycol were measured and mixed. Then, 5 mg of phytic acid-doped polyaniline powder was weighed and added to the mixed solution. The mixture was ultrasonically dispersed in an ultrasonic cleaner (set to 50°C) until fully dissolved, resulting in a homogeneous polyaniline solution. 0.25 g of polyvinyl alcohol was weighed and added to the polyaniline solution, and the mixture was stirred at 85°C for 2 hours (600 r / min) using a thermostatic magnetic stirrer to ensure complete dissolution, obtaining a mixed solution. The solution was then frozen in a refrigerator for 30 minutes and thawed at room temperature for 24 hours. The resulting antifreeze PVA / PANI gel was then tested for its mechanical and electrochemical properties.

[0098] Comparative Example 6

[0099] (1) Preparation of phytic acid-doped polyaniline

[0100] Weigh 0.286 g of ammonium persulfate into bottle A, add 1 ml of distilled water to dissolve it completely, and then cool it to 4°C in a refrigerator. Measure 2 ml of distilled water into bottle B, and add 920 μL of phytic acid and 375 μL of aniline sequentially using a pipette. Stir with a magnetic stirrer until the solution is homogeneous, and then cool it to 4°C in a refrigerator. Combine the solutions from bottles A and B and refrigerate for at least 12 hours. Then filter using a vacuum pump, wash three times with ethanol, and twice with deionized water to obtain a powder. Finally, dry the powder in an oven at 50°C for 2 hours and store it in a sealed bag. Figure 1 )

[0101] (2) Preparation of antifreeze PVA / PANI gel

[0102] First, 2.5 ml of deionized water and 7.5 ml of ethylene glycol were measured and mixed. Then, 5 mg of phytic acid-doped polyaniline powder was weighed and added to the mixed solution. The mixture was ultrasonically dispersed in an ultrasonic cleaner (set to 50°C) until fully dissolved, resulting in a homogeneous polyaniline solution. 0.25 g of polyvinyl alcohol was weighed and added to the polyaniline solution, and stirred at 85°C for 2 hours (600 r / min) using a thermostatic magnetic stirrer to ensure complete dissolution, obtaining a mixed solution. The solution was then frozen in a refrigerator for 30 minutes and thawed at room temperature for 24 hours. The resulting antifreeze PVA / PANI gel was then tested for its mechanical and electrochemical properties.

[0103] The performance of the hydrogels prepared in Examples 1-5, the polyaniline powders prepared in Comparative Examples 1-2, and the hydrogels prepared in Comparative Examples 3-6 was tested.

[0104] 1. Infrared spectroscopy test

[0105] Fourier transform infrared spectroscopy (FT-IR) is a common method for characterizing the structure and composition of powdered samples. This study uses a Fourier transform infrared spectrometer to characterize the structure of antifrozen PVA / PANI gel. First, a sample is taken, and the instrument is turned on. The instrument is allowed to stabilize for a period of time, then the spectrometer program is run, parameters are set, and the testing range is 4400-400 cm⁻¹. -1 The number of scans is 32. First, the background is scanned, then the sample is loaded and the sample scanning begins. After the scan is completed, the file is saved.

[0106] 2. Mechanical performance testing

[0107] PANI is a rigid molecule, so introducing PANI into PVA can improve the mechanical properties of the gel. Gels of equal length prepared from phytic acid, hydrochloric acid, and dedoped PANI were stretched until they broke, and their elongation at break was calculated.

[0108] 3. Electrochemical performance testing

[0109] Electrochemical performance testing of the hydrogel was conducted using a three-electrode system. The working electrode was the hydrogel, and the reference electrode was a calomel electrode. An acidic electrolyte was used during testing. Before the experiment, the sample was immersed in a 1 mol / L saturated H₂SO₄ solution for a period of time. Then, the computer was connected, the electrochemical workstation was turned on, and the corresponding main parameters were set. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were performed, all at room temperature.

[0110] Infrared analysis was performed on the hydrogel prepared in Example 1, and the results are as follows: Figure 5 As shown.

[0111] Based on the infrared spectrum analysis of polyvinyl alcohol, it can be concluded that at 3265 cm⁻¹... -1 The peak value at 1650 cm⁻¹ indicates the presence of -OH groups between or within polyvinyl alcohol molecules. -1 The peak value at this point indicates that there is an asymmetric -OH stretching vibration characteristic absorption peak within the molecular structure. Figure 5 The image shows the infrared spectrum of the antifreeze PVA / PANI gel. Figure 5 As shown, 3462cm -1 The peak value at 1459 cm⁻¹ indicates the presence of the characteristic absorption peak of the -OH stretching vibration; -1 The peak value at the point indicates the stretching vibration of the benzene ring; after the addition of PANI, the characteristic peak in the figure shifts, that is, the addition of PANI changes the skeleton of polyvinyl alcohol, and PANI and PVA are strongly integrated, indicating that PANI was successfully added to PVA.

[0112] The mechanical properties of the polyaniline prepared in Example 1, Comparative Example 1, and Comparative Example 2 were tested.

[0113] The mechanical properties of antifreeze PVA / PANI gels prepared with phytic acid, hydrochloric acid, and undoped polyaniline were compared using tensile tests. As shown in Table 4, the elongation at break of the phytic acid-doped polyaniline gel was 180%, that of the hydrochloric acid-doped polyaniline gel was 120%, and that of the undoped polyaniline gel was 100%. This is likely due to the presence of numerous amino groups on aniline. Phytic acid, as an organic acid, allows each phytic acid molecule to chain with several PANI molecules, creating a three-dimensional network structure. Furthermore, the long alkyl side chains in phytic acid enhance the stability and solubility of polyaniline, thus improving the gel's mechanical properties. Hydrochloric acid, as an inorganic acid, results in relatively weak stability in polyaniline synthesized through doping. Therefore, the tests demonstrate that the phytic acid-doped polyaniline gel exhibits the best mechanical properties.

[0114] Table 4. Elongation at break of polyaniline gels with different acid doping

[0115]

[0116] To further demonstrate the excellent mechanical properties of the antifreeze PVA / PANI gel prepared with phytic acid-doped polyaniline, various mechanical properties were studied. For example... Figure 6 As shown, the antifreeze PVA / PANI hydrogel can lift a weight of 200g. Furthermore, in Figure 6 (bd) demonstrates the hydrogel's resistance to glass rod penetration. For example... Figure 6 As shown in (e.g.), the hydrogel was subjected to knotted stretching, torsional stretching, and notched stretching. These tests all demonstrated that the antifreeze PVA / PANI gel possesses excellent mechanical properties.

[0117] Conductivity tests were performed on the hydrogels prepared in Examples 1-5.

[0118] Due to the presence of PVA, the antifreeze PVA / PANI gel exhibits excellent electrical conductivity. For example... Figure 7 As shown in (ae), gels doped with phytic acid and polyaniline with contents of 5 mg, 10 mg, 15 mg, 20 mg and 25 mg can be knotted and stretched to light up LED bulbs. The LED bulbs are brightest when the polyaniline content is 5 mg.

[0119] Electrochemical performance tests were performed on the hydrogels prepared in Examples 1-5.

[0120] In investigating the electrochemical performance of the hydrogels prepared in Examples 1-5, cyclic voltammetry (CV) tests were performed. The area of ​​the CV curve reflects the specific capacitance of the raw materials. The specific capacitance of the gel was calculated based on the ratio of the integral area of ​​the CV curve to the scan rate. Cyclic voltammetry curves for different PANI contents at a scan rate of 5 mV / s are shown below. Figure 8 As shown in Table 5, the specific capacitance values ​​of gels with different PANI contents are shown in Table 5 below.

[0121] Table 5. Specific capacitance values ​​of PANI gels with different contents at a scan rate of 5 mV / s.

[0122]

[0123] Depend on Figure 8 It can be seen that when the scan rate is 5 mV / s, the area of ​​the measured CV curve gradually decreases with the increase of polyaniline dosage, and the specific capacitance of the gel also gradually decreases. When the PANI dosage is 5 mg, the specific capacitance C of the gel reaches the highest value of 6.26 F / g (see Table 5). Therefore, when the scan rate is constant at 5 mV / s, the gel exhibits the best capacitance performance when the PANI dosage is 5 mg. This is because when the polyaniline content is 5 mg, the gel forms a better three-dimensional network porous structure, which is more beneficial for the dispersion and transport of electrolyte ions. With the increase of PANI mass, the resistance to the diffusion of electrolyte ions to the electrode material also increases during CV testing, making it difficult for electrolyte ions to enter the interior of the conductive hydrogel during the test. This reaction only occurs on the surface of the gel, and not all PANI reacts. Therefore, with the increase of PANI, the specific capacitance of the gel gradually decreases.

[0124] When the PANI content is 5 mg, the cyclic voltammetry curves at different scan rates are as follows: Figure 9 As shown in Table 6 below, the specific capacitance values ​​at different scan rates are as follows.

[0125] Table 6. Specific capacitance values ​​of the gel at different scan rates when the PANI content is 5 mg.

[0126]

[0127] Depend on Figure 9 It can be seen that when the PANI content is fixed at 5 mg, the area of ​​the measured CV curve gradually decreases with the increase of the scan rate, and the specific capacitance value C of the gel also gradually decreases. When the scan rate is 5 mV / s, the specific capacitance value C of the gel reaches the highest value of 6.26 F / g (see Table 6). This indicates that the higher the scan rate, the lower the rate capability of the gel, and the less suitable the gel is as an electrode material.

[0128] The hydrogels prepared in Example 1 and those prepared in Comparative Examples 3-6 were subjected to electrochemical performance tests at 0°C. The specific capacitance values ​​are shown in Table 7 below.

[0129] Table 7. Specific capacitance values ​​of different gels at 0℃

[0130]

[0131] The results above show that the antifreeze effect is best when the ratio of ethylene glycol to deionized water is 1:1.

[0132] Impedance spectroscopy analysis was performed on the hydrogel prepared in Example 1, and the results are as follows: Figure 10 As shown.

[0133] Impedance spectroscopy is commonly used in scientific studies to investigate charge transfer in electrodes and the resistance to ion diffusion at electrode interfaces. Figure 1 Generally, it can be divided into two parts: a low-frequency region and a high-frequency region. In the high-frequency region, it exhibits an arc-shaped curve, while in the low-frequency region, it appears as an approximately straight line. When the slope of the curves in the low-frequency and high-frequency regions approaches 90°, it indicates that the gel has excellent capacitive properties. Figure 10 It can be seen that the slopes of the two regions are close to 90°, which indicates that the capacitance value of the antifreeze PVA / PANI gel is good when the amount of PANI is 5mg.

[0134] The above description is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing an antifreeze hydrogel for flexible wearable devices, characterized in that, Includes the following steps: S1 Adds acid-doped polyaniline to the mixed solution and mixes it evenly to obtain a polyaniline solution; S2. Polyvinyl alcohol is added to the polyaniline solution and stirred until it is fully dissolved to obtain a mixed solution; S3 First, place the mixed solution in a refrigerator to freeze, then take it out and thaw it at room temperature to obtain an antifreeze hydrogel; The mixed solution is a mixture of deionized water and ethylene glycol, wherein the volume ratio of deionized water to ethylene glycol is 1:

1. In step S1, the mass-to-volume ratio (g / ml) of the acid-doped polyaniline to the mixed solution is 1:

1. In step S2, the amount of polyvinyl alcohol added is 50 times the mass of the acid-doped polyaniline.

2. The method for preparing the antifreeze hydrogel for flexible wearable devices according to claim 1, characterized in that: The acid-doped polyaniline powder is phytic acid-doped polyaniline powder.

3. The method for preparing the antifreeze hydrogel for flexible wearable devices according to claim 2, characterized in that, The preparation method of the phytic acid-doped polyaniline includes the following steps: S11 Dissolves ammonium persulfate thoroughly in distilled water and then cools it to 4°C in a refrigerator to obtain mixed solution A; S12 mixes distilled water, phytic acid and aniline evenly and then cools it in a refrigerator to 4°C to obtain mixed solution B; S13 Mix solution A and solution B evenly, place in a freezer for refrigeration for no less than 12 hours, and obtain phytic acid-doped polyaniline.

4. The method for preparing the antifreeze hydrogel for flexible wearable devices according to claim 3, characterized in that, The method for preparing phytic acid-doped polyaniline further includes a post-processing step: S14 The crude phytic acid-doped polyaniline obtained in S13 is filtered, washed, and then dried in an oven to obtain the refined phytic acid-doped polyaniline.

5. The antifreeze hydrogel prepared by the preparation method according to any one of claims 1-4.

6. The application of the antifreeze hydrogel as described in claim 5 in the preparation of flexible wearable electronic devices.

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