A hydrogel with high strength and high ionic conductivity and its preparation method and application

Abstract

The present invention discloses a high-strength and high-ionic conductivity hydrogel and its preparation method and application, which belongs to the field of polymer material technology. The method comprises the following steps: S1. dissolving acrylamide in deionized water, adding an initiator and glyoxal to obtain a mixed solution, and then performing a grafting reaction under a pH of 3 to 4 to obtain a glyoxal-grafted polyacrylamide solution; S2. adding a polyvinyl alcohol solution to the glyoxal-grafted polyacrylamide solution, adding a boric acid aqueous solution while stirring, adding a cross-linking agent after the reaction, stirring and dissolving, transferring to a mold, and heating to obtain a hydrogel. The hydrogel patch prepared by the present invention has both excellent ionic conductivity and high mechanical strength, which solves the problem that it is difficult to achieve both high mechanical strength and excellent conductivity in the prior art hydrogel.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a hydrogel with high strength and high ionic conductivity, and a preparation method and application thereof. Background Art

[0002] Flexible wearable electronic devices have attracted widespread attention from both academia and industry, but their application and development are severely hampered by issues such as insufficient mechanical strength and poor electrical conductivity. Conventional liquid electrolytes are prone to leakage, have low electrochemical stability, and evaporate rapidly. Hydrogel electrolytes, composed of a polymer network and an electrolyte solution, are quasi-solid-state electrolytes that retain large amounts of ionic solution without leakage while also exhibiting excellent flexibility and electrical conductivity. These properties make hydrogels ideal electrolyte materials for flexible electronic devices, significantly improving their overall performance.

[0003] The main challenges faced by existing hydrogel electrolytes include insufficient mechanical properties and low ionic conductivity due to insufficient cross-linking. Therefore, current research focuses on improving the mechanical properties and ionic conductivity of hydrogels through various methods. Common hydrogel electrolytes include those based on polyacrylamide and polyvinyl alcohol, which conduct electricity by promoting the directional migration of free mobile ions in the gel network when an electric field is applied. Recently, flexible hydrogel electrolytes with a variety of new designs have been reported. For example, the addition of proteins to the composite gel has been shown to effectively enhance adhesion, improve low-temperature resistance and retain a large amount of electrolyte solution. However, the mechanical properties provided by these composite gels are often relatively limited. The combination of chemical coordination and physical cross-linking has been shown to significantly improve mechanical properties. For example, by incorporating Fe 3+ ions mixed with polyvinyl acetate (PVAA) / polyacrylamide (PAM) hydrogels form a dual-network hydrogel system with high tensile strength, compressibility, and self-healing properties. Furthermore, researchers have synthesized hydrogel electrolytes by crosslinking carboxyl groups of polyvinyl alcohol with COO-Fe bonds in the presence of Zn(NO3)2 and MnSO4. This results in improved mechanical properties due to the strengthening of the crosslinked network. However, ionic conductivity is also a critical performance criterion for electrolyte materials. Striking a balance between improved mechanical properties and ionic conductivity remains a significant challenge for hydrogel electrolytes in flexible electronics. The elastic modulus reflects a material's ability to resist deformation under stress. A higher elastic modulus indicates a lower elastic deformation under the same stress. In hydrogel patch batteries, the hydrogel is in full contact with the electrode ink. Excessive deformation of the hydrogel due to tension or compression can cause the electrode ink to break and fall out. Therefore, a high elastic modulus is desirable for hydrogels, and both the elastic modulus and mechanical properties under flexural fatigue are particularly important for wearable drug delivery patches. Summary of the Invention

[0004] In view of the above shortcomings of the prior art, one of the objectives of the present invention is to provide a method for preparing a high-strength, high-ionic conductivity hydrogel. The prepared hydrogel patch has both excellent ionic conductivity and high mechanical strength, solving the problem that the prior art hydrogel is difficult to achieve both high mechanical strength and excellent conductivity.

[0005] The above-mentioned object of the present invention is achieved through the following technical solutions:

[0006] A method for preparing a hydrogel with high strength and high ionic conductivity comprises the following steps:

[0007] S1. Acrylamide was dissolved in deionized water, an initiator and glyoxal were added to obtain a mixed solution, and then the grafting reaction was carried out at a pH of 3 to 4 to obtain a glyoxal-grafted polyacrylamide solution;

[0008] S2. Add polyvinyl alcohol solution to the glyoxal-grafted polyacrylamide solution, add boric acid aqueous solution while stirring, add cross-linking agent after the reaction, stir to dissolve, transfer to a mold, and heat to obtain a hydrogel.

[0009] The present invention first adopts glyoxal to carry out modification treatment to acrylamide, an aldehyde group in glyoxal reacts with the amide group in acrylamide to generate hydroxyl, and initiates polymerization reaction simultaneously, and its unreacted aldehyde group is then introduced into the middle of the chain segment of polyacrylamide, obtains glyoxal-polyacrylamide, by adopting glyoxal to carry out modification treatment to acrylamide, the number of hydroxyl groups on the molecular chain can be increased, and the crosslinking between polyacrylamide and boric acid and polyvinyl alcohol can be effectively promoted. Then, using glyoxal grafted polyacrylamide and polyvinyl alcohol as raw materials, a semi-interpenetrating polymer network is formed by combining dynamic borate and hydrogen bond crosslinking, and a hydrogel of a double network structure is successfully synthesized. The prepared hydrogel has high ionic conductivity, tensile strength and modulus, and not only electrical conductivity significantly improves, but mechanical property has also been enhanced, solving the problem that the high mechanical strength of existing conductive hydrogels and excellent electrical conductivity are difficult to obtain both. In addition, this hydrogel can still maintain its electrical conductivity and tensile property after experiencing thousands of bending cycles, demonstrating good fatigue resistance. In mice, the drug delivery patch prepared by this hydrogel has also confirmed its effective transdermal drug delivery effect.

[0010] Preferably, the concentration of acrylamide in the mixed solution is 30%wt~50%wt, and the concentration of glyoxal is 9%wt~15%wt.

[0011] Preferably, the glyoxal is a glyoxal aqueous solution with a concentration of 30% wt to 50% wt, and the mass ratio of the glyoxal aqueous solution to acrylamide is (1 to 6): (2 to 8).

[0012] Preferably, the initiator is potassium persulfate and / or ammonium persulfate, and the mass of the initiator is 0.1% to 2.5% of the mass of acrylamide.

[0013] Preferably, the mass ratio of the glyoxal-grafted polyacrylamide solution to the polyvinyl alcohol solution is (3-9):(3-10), and the concentration of polyvinyl alcohol in the polyvinyl alcohol solution is 5%wt-10%wt.

[0014] More preferably, the mass ratio of the glyoxal-grafted polyacrylamide solution to the polyvinyl alcohol solution is (3-9):(3-7), and the concentration of polyvinyl alcohol in the polyvinyl alcohol solution is 5%wt-10%wt.

[0015] Preferably, the mass ratio of the glyoxal grafted polyacrylamide solution to the boric acid aqueous solution is (3-9):(2-8), and the concentration of boric acid in the boric acid aqueous solution is 2%wt-6%wt.

[0016] More preferably, the mass ratio of the glyoxal-grafted polyacrylamide solution to the boric acid aqueous solution is (3-9):(4-6), and the concentration of boric acid in the boric acid aqueous solution is 2%wt-6%wt.

[0017] Preferably, in step S1, the grafting reaction is carried out at 25-45° C. and stirring at 100-300 rpm for 1-5 hours.

[0018] Preferably, in step S2, the reaction temperature is 10-50° C., and the reaction time is 1.5-5 h; the heating temperature is 30-70° C., and the reaction time is 1-5 h.

[0019] Another object of the present invention is to provide a hydrogel with high strength and high ionic conductivity prepared by the preparation method.

[0020] Another object of the present invention is to provide the use of the high-strength and high-ionic conductivity hydrogel in flexible wearable devices, drug carriers or biological tapes.

[0021] The present invention further provides a wearable drug delivery hydrogel patch using the hydrogel as an electrolyte material, which is prepared by the following method:

[0022] M1. The zinc powder, ZnO, carbon black, PVDF and NMP solvent were mixed to prepare a zinc electrode ink, and the ink was deposited on the surface of the copper foil to obtain a negative electrode;

[0023] M2. Ni(OH)2, carbon black, and PVDF were mixed to form a nickel electrode ink, which was deposited on a copper foil surface to obtain a positive electrode.

[0024] M3. After the hydrogel is fully soaked in KOH electrolyte, it is assembled with the positive electrode, negative electrode, medical tape, and drug-loaded medical cotton into an iontophoresis patch.

[0025] Compared with the prior art, the present invention is beneficial in that:

[0026] (1) The hydrogel prepared by the present invention exhibits a high ionic conductivity, which reaches 11.33 S / m after ion adsorption. It also has excellent mechanical properties, with a tensile strength of 491.27 kPa and a modulus of 1066.11 kPa, and excellent mechanical properties.

[0027] (2) The hydrogel of the present invention can still maintain good conductivity and tensile properties after 1000 bending cycles, showing strong anti-fatigue properties.

[0028] (3) The ion introduction patch made of the hydrogel of the present invention showed an effective transdermal drug delivery effect in mice. The transdermal drug delivery experiment conducted on mouse skin of the present invention showed that ion penetration can effectively improve the drug permeability. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The swelling condition of the hydrogel prepared by the present invention in the electrolyte; wherein, Figure 1 (A) is the swelling of GB4P5 gel in 0-5 mol / L KOH solution. Figure 1 (B) shows the swelling of six gels in 1 mol / L KOH solution. Figure 1 (C) is the mass retention capacity of the GB4P5 gel after swelling in KOH solutions of different concentrations for 24 h. Figure 1 (D) is the mass retention capacity of the six gels after swelling in 1 mol / L KOH solution for 24 h. Figure 1 (E) is the optical image of GB4P5 hydrogel before swelling. Figure 1 (F) Optical image of GB4P5 hydrogel after swelling in 1 mol / L KOH solution for 24 h;

[0030] Figure 2 The mechanical properties of the hydrogel prepared by the present invention are shown in FIG. Figure 2 (A) is the tensile stress-strain curve of dumbbell-shaped hydrogel; Figure 2 (B) is the modulus of the hydrogel at break when stretched; Figure 2 (C) is the tensile stress-strain curve of the gel sample after bending 1000 times; Figure 2 (D) Retention rate of maximum breaking strength and maximum strain value of the four gels before and after bending; Figure 2 (E) is the compressive stress-strain curve of the bulk hydrogel; Figure 2 (F) Compression stress-strain curve of GB4P5 gel after 100 cycles of compression;

[0031] Figure 3 The conductive properties of the hydrogel prepared by the present invention; wherein, Figure 3 (A) is the electrochemical impedance spectroscopy of the hydrogel. Figure 3 (B) is the ionic conductivity of the hydrogel, Figure 3 (C) is the resistance change rate curve of GB6P3 during the continuous bending cycle from 0s to 1800s. Figure 3 (D) is the resistance change rate curve of GB6P3 during continuous bending cycle from 1000s to 1050s;

[0032] Figure 4 is a schematic diagram of the patch of the present invention; wherein, Figure 4 (A) is a schematic diagram of the structure of the ion introduction patch of the present invention, Figure 4 (B) is a schematic diagram of the patch of the present invention attached to the skin surface of a human arm, Figure 4 (C) Schematic diagram of simulating in vitro transdermal permeation experiments using diffusion cell experiments;

[0033] Figure 5 is the electrochemical performance of the patch battery of the present invention; wherein, Figure 5 (A) is the electrochemical impedance spectrum of the patch battery of the present invention, Figure 5 (B) is the charge and discharge curve of the patch battery at different current densities in the voltage window of 0-1.2V. Figure 5 (C) is the battery at 1mA / cm 2 Constant current charge and discharge curve under ;

[0034] Figure 6 is the drug administration effect of the iontophoresis patch of the present invention; wherein, Figure 6 (A) is the drug penetration on mouse skin, Figure 6 (B) is the effect of different substances on the permeability, Figure 6 (C) is the drug penetration on pig skin;

[0035] Among them: 1. Skin; 2. Iontophoresis patch; 201. Positive and negative electrodes; 202. Hydrogel electrolyte; 203. Medical tape; 204. Drug-loaded medical cotton; 3. Air outlet; 4. Vertical diffusion cell; 5. Ultrapure water. DETAILED DESCRIPTION

[0036] The technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0037] The present invention provides a method for preparing a hydrogel with high strength and high ionic conductivity, comprising the following steps:

[0038] S1. Acrylamide was dissolved in deionized water, an initiator and glyoxal were added to obtain a mixed solution, and then the grafting reaction was carried out at a pH of 3 to 4 to obtain a glyoxal-grafted polyacrylamide solution;

[0039] S2. Add polyvinyl alcohol solution to the glyoxal-grafted polyacrylamide solution, add boric acid aqueous solution while stirring, add cross-linking agent after the reaction, stir to dissolve, transfer to a mold, and heat to obtain a hydrogel.

[0040] In step S1, the concentration of acrylamide in the mixed solution is 30%wt~50%wt, and the concentration of glyoxal is 9%wt~15%wt.

[0041] In step S1, the glyoxal is a glyoxal aqueous solution with a concentration of 30% wt to 50% wt, and the mass ratio of the glyoxal aqueous solution to acrylamide is (1 to 6): (2 to 8).

[0042] In step S1, the initiator is potassium persulfate and / or ammonium persulfate, and the mass of the initiator is 0.1% to 2.5% of the mass of acrylamide.

[0043] In step S2, the mass ratio of the glyoxal-grafted polyacrylamide solution to the polyvinyl alcohol solution is (3-9):(3-10), and the concentration of polyvinyl alcohol in the polyvinyl alcohol solution is 5%wt-10%wt.

[0044] In step S2, the mass ratio of the glyoxal-grafted polyacrylamide solution to the boric acid aqueous solution is (3-9):(2-8), and the concentration of boric acid in the boric acid aqueous solution is 2%wt-6%wt.

[0045] In step S1, the grafting reaction is carried out under the following conditions: stirring at 100-300 rpm for 1-5 hours at 25-45°C.

[0046] In step S2, the reaction temperature is 10-50° C., and the reaction time is 1.5-5 h; the heating temperature is 30-70° C., and the reaction time is 1-5 h.

[0047] The method for preparing a high-strength, high-ionic conductivity hydrogel according to a specific embodiment of the present invention comprises the following steps:

[0048] S1. Dissolve 3 g of acrylamide in 6 ml of deionized water, add 10 mg of potassium persulfate and 3 g of glyoxal (40% wt) solution, and stir at 300 rpm for 1 h at a pH of 3-4 and 45°C to obtain a glyoxal-grafted polyacrylamide (GPAM) solution.

[0049] S2. To 4 g of GPAM solution, add an appropriate amount of polyvinyl alcohol (PVA) (8% wt) solution at a steady rotation speed of 400 rpm. Then, slowly add an appropriate amount of H3BO3 (4% wt) solution. Stir at 50°C for 1.5 h. Then, add 5 mg of N,N'-methylenebisacrylamide (MBA) and stir to dissolve it evenly to obtain a mixture. After removing bubbles, the mixture is immediately transferred to a mold of a specific shape and heated in an oven at 70°C for 1.5 h to obtain GPAM-B-PVA hydrogel samples of different shapes.

[0050] Examples 1 to 6 all prepared hydrogels according to the above method, with the only difference being that the masses of the polyvinyl alcohol solution and the H3BO3 solution in step S2 were different. The masses of the polyvinyl alcohol solution and the H3BO3 solution added in each example are shown in Table 1.

[0051] Table 1

[0052]

[0053] Figure 1 The swelling condition of the hydrogel prepared by the present invention in the electrolyte. Figure 1 (A) is the swelling of GB4P5 gel in 0-5 mol / L KOH solution. Figure 1 (B) shows the swelling of six gels in 1 mol / L KOH solution. Figure 1 (A) and Figure 1 (B) It can be seen that the swelling rate of the hydrogel decreases in high-concentration electrolyte. The increase of H3BO3 and PVA content increases the cross-linking density and also limits the swelling, indicating that the swelling behavior of the hydrogel is affected by the electrolyte concentration and its own cross-linking structure. Figure 1 (C) is the mass retention capacity of the GB4P5 gel after swelling in KOH solutions of different concentrations for 24 h. Figure 1 (D) is the mass retention capacity of the six gels after swelling in 1 mol / L KOH solution for 24 h. Figure 1 (C) and Figure 1(D) It can be seen that the hydrogel exhibits strong ion retention ability in high concentration KOH solution, and the content of H3BO3 and PVA has little effect on the ion retention ability of the hydrogel; Figure 1 (E) is the optical image of GB4P5 hydrogel before swelling. Figure 1 (F) is the optical image of GB4P5 hydrogel after swelling in 1 mol / L KOH solution for 24 h; Figure 1 (E) and Figure 1 (F) It can be seen that the width of the gel before swelling was 1.5 cm, and the width after swelling was about 1.91 cm, an increase of about 27.3%. The size of the hydrogel increased significantly after swelling.

[0054] The mechanical properties of hydrogels, especially their tensile and compressive properties, are crucial for their applications in flexible electronic devices. Figure 2 The mechanical properties of the hydrogel prepared by the present invention are shown in FIG. Figure 2 (A) is the tensile stress-strain curve of dumbbell-shaped hydrogel; Figure 2 (B) is the modulus of the hydrogel at break when stretched; Figure 2 (C) is the tensile stress-strain curve of the gel sample after bending 1000 times; Figure 2 (D) Retention rate of maximum breaking strength and maximum strain value of the four gels before and after bending; Figure 2 (E) is the compressive stress-strain curve of the bulk hydrogel; Figure 2 (F) shows the compressive stress-strain curve of the GB4P5 hydrogel after 100 cycles of compression. The figure shows that the amount of boric acid and polyvinyl alcohol used affects the tensile properties of the hydrogel. GB0P5 exhibits lower tensile stress and elongation due to the lack of borate crosslinks, while GB4P5 exhibits the highest breaking strength and modulus due to the high crosslink density between GPAM and PVA chains. The hydrogel also exhibits excellent fatigue resistance, maintaining its tensile and compressive strength even after multiple bending and compression cycles. These properties make the hydrogel an ideal material for flexible electronic devices, capable of withstanding the repetitive stresses of everyday use without sacrificing performance.

[0055] The internal resistance and ionic conductivity of the hydrogel were measured by electrochemical impedance spectroscopy (EIS). Figure 3 The conductive properties of the hydrogel prepared by the present invention; wherein, Figure 3 (A) is the electrochemical impedance spectroscopy of the hydrogel. Figure 3 (B) is the ionic conductivity of the hydrogel, Figure 3 (A) and Figure 3(B) It can be seen that the conductivity of the hydrogel is not only affected by the number of adsorbed ions, but also related to the characteristics of the pore size as an ion transport channel. Although GB4P5 has the strongest adsorption capacity, its thin pore wall may affect the direction of ion movement, while the thick wall structure and large pores of GB6P7 are conducive to the formation of stable ion channels, thereby promoting the directional movement of ions. GB6P5 exhibits the highest conductivity of 11.46 S / m. Figure 3 (C) is the resistance change rate curve of GB6P3 during the continuous bending cycle from 0s to 1800s. Figure 3 (D) is the resistance change rate curve of GB6P3 during the continuous bending cycle from 1000s to 1050s; Figure 3 (C) and Figure 3 (D) It can be seen that during the continuous bending cycle, the resistance change rate of the hydrogel remains within 15%, showing good mechanical properties and resistance stability, but long-term bending may cause partial damage to the ion transport channel and gradually increase the resistance value.

[0056] This embodiment also provides a method for preparing an iontophoresis patch, comprising the following steps:

[0057] M1 zinc powder, ZnO, carbon black, PVDF and NMP solvent were mixed to prepare a zinc electrode ink, the ink was printed on the surface of the copper foil to obtain a negative electrode;

[0058] M2. Ni(OH)2, carbon black and PVDF were mixed to form a nickel electrode ink, which was then printed on a copper foil surface to obtain a positive electrode.

[0059] M3. A thin film of GB6P3 hydrogel was fully soaked in 4 M KOH electrolyte to obtain a hydrogel electrolyte 202. The hydrogel electrolyte 202 was then assembled with positive and negative electrodes 201, medical tape 203, and drug-loaded medical cotton 204 to form an iontophoresis patch 2 (e.g., Figure 4 A), and then stick the patch on the surface of the skin 1 of the human arm (as shown in Figure 4 B); then the diffusion cell experiment was used to simulate the in vitro transdermal experiment. The experimental schematic diagram is shown in Figure 4 As shown in C, the skin 1 with the ion introduction patch 2 is placed on a device with an air outlet 3 and a vertical diffusion cell 4, and the vertical diffusion cell 4 is filled with ultrapure water 5.

[0060] Figure 5 is the electrochemical performance of the patch battery of the present invention; wherein, Figure 5 (A) is the electrochemical impedance spectrum of the patch battery of the present invention, Figure 5 (B) is the charge and discharge curve of the patch battery at different current densities in the voltage window of 0-1.2V. Figure 5(C) is the battery at 1mA / cm 2 Constant current charge and discharge curve under Figure 5 As can be seen from (A), the equivalent internal resistance of the Ni-Zn battery (including electrode resistance, electrolyte resistance and contact resistance) is only 0.37Ω. This is due to the effective adsorption of KOH electrolyte by the hydrogel, which increases the internal conductivity of the gel. Figure 5 (B) and Figure 5 (C) It can be seen that the charge-discharge curves at different current densities have similar shapes and have relatively obvious charge-discharge platforms, indicating that a reversible redox reaction occurs during the charge-discharge process.

[0061] Figure 6 is the drug administration effect of the iontophoresis patch of the present invention; wherein, Figure 6 (A) is the drug penetration on mouse skin, Figure 6 (B) is the effect of different substances on the permeability, Figure 6 (C) shows the drug permeation rate through pig skin. As shown in the figure, iontophoresis effectively enhances drug transdermal delivery using a low-resistance patch. Experiments show that its efficiency far exceeds that of passive diffusion, and certain substances, such as potassium chloride, can further enhance the effect. This method shows great potential in the field of drug delivery.

[0062] Example 7

[0063] The method for preparing the high-strength and high-ionic-conductivity hydrogel of this embodiment comprises the following steps:

[0064] S1. Dissolve 3 g of acrylamide in 6 ml of deionized water, add 10 mg of potassium persulfate, and stir at 300 rpm for 1 h at a pH of 3-4 and 45°C to obtain a polyacrylamide (PAM) solution.

[0065] S2. To 4 g of PAM solution, 3 g of polyvinyl alcohol (PVA) (8% wt) solution was added at a steady rotation speed of 400 rpm. Then, 6 g of H3BO3 (4% wt) solution was slowly added thereto. The mixture was stirred at 50°C for 1.5 h. Finally, 5 mg of N,N'-methylenebisacrylamide (MBA) was added and stirred to dissolve uniformly to obtain a mixture. After removing bubbles, the mixture was immediately transferred to a mold of a specific shape and heated in an oven at 70°C for 1.5 h to obtain PAM-B-PVA hydrogel samples of different shapes.

[0066] That is, Example 7 is substantially the same as Example 6, with the only difference being that glyoxal is not added in step S1.

[0067] Compared with the GB6P3 hydrogel, the hydrogel obtained in this comparative example has a poor ability to adsorb ions, which leads to lower ionic conductivity, which is only 2.16S / m; in addition, the mechanical properties of the hydrogel in this comparative example are also worse, with a tensile strength of 102.25 kPa and a modulus of 248.42 kPa.

[0068] Example 8

[0069] The method for preparing the high-strength and high-ionic-conductivity hydrogel of this embodiment comprises the following steps:

[0070] S1. Dissolve 8 g of acrylamide in 6 ml of deionized water, add 50 mg of potassium persulfate and 6 g of glyoxal (40% wt) solution, and stir at 300 rpm for 1 h at a pH of 3-4 and 35°C to obtain a glyoxal-grafted polyacrylamide (GPAM) solution.

[0071] S2. To 9 g of GPAM solution, 5 g of polyvinyl alcohol (PVA) (8% wt) solution was added at a steady rotation speed of 600 rpm. Then, 6 g of H3BO3 (4% wt) solution was slowly added. The mixture was stirred at 50°C for 5 h. Finally, 5 mg of N,N'-methylenebisacrylamide (MBA) was added and stirred to dissolve uniformly to obtain a mixture. After removing bubbles, the mixture was immediately transferred to a mold of a specific shape and heated in an oven at 30°C for 5 h to obtain GPAM-B-PVA hydrogel samples of different shapes.

[0072] Example 9

[0073] The method for preparing the high-strength and high-ionic-conductivity hydrogel of this embodiment comprises the following steps:

[0074] S1. Dissolve 2 g of acrylamide in 1 ml of deionized water, add 10 mg of potassium persulfate and 1 g of glyoxal (40% wt) solution, and stir at 100 rpm for 1 h at a pH of 3-4 and 25°C to obtain a glyoxal-grafted polyacrylamide (GPAM) solution.

[0075] S2. To 3 g of GPAM solution, add 5 g of polyvinyl alcohol (PVA) (8% wt) solution at a steady rotation speed of 100 rpm. Then, slowly add 6 g of H3BO3 (4% wt) solution. Stir at 10°C for 5 h. Then, add 5 mg of N,N'-methylenebisacrylamide (MBA) and stir to dissolve it evenly to obtain a mixture. After removing bubbles, the mixture is immediately transferred to a mold of a specific shape and heated in an oven at 30°C for 5 h to obtain GPAM-B-PVA hydrogel samples of different shapes.

[0076] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a hydrogel with high strength and high ionic conductivity, characterized in that: The following steps are involved: S1. Acrylamide was dissolved in deionized water, an initiator and glyoxal were added to obtain a mixed solution, and then the grafting reaction was carried out at a pH of 3 to 4 to obtain a glyoxal-grafted polyacrylamide solution; S2. Add polyvinyl alcohol solution to the glyoxal-grafted polyacrylamide solution, add boric acid aqueous solution while stirring, add cross-linking agent after the reaction, stir to dissolve, transfer to a mold, and heat to obtain a hydrogel.

2. The method for preparing a hydrogel with high strength and high ionic conductivity according to claim 1, characterized in that: The concentration of acrylamide in the mixed solution is 30 wt % to 50 wt %, and the concentration of glyoxal is 9 wt % to 15 wt %.

3. The method for preparing a hydrogel with high strength and high ionic conductivity according to claim 1, characterized in that: The glyoxal is a glyoxal aqueous solution with a concentration of 30 wt% to 50 wt%, and the mass ratio of the glyoxal aqueous solution to acrylamide is (1 to 6): (2 to 8).

4. The method for preparing a hydrogel with high strength and high ionic conductivity according to claim 1, characterized in that: The initiator is potassium persulfate and / or ammonium persulfate, and the mass of the initiator is 0.1% to 2.5% of the mass of acrylamide.

5. The method for preparing a hydrogel with high strength and high ionic conductivity according to claim 1, characterized in that: The mass ratio of the glyoxal-grafted polyacrylamide solution to the polyvinyl alcohol solution is (3-9):(3-10), and the concentration of the polyvinyl alcohol in the polyvinyl alcohol solution is 5wt%-10wt%.

6. The method for preparing a hydrogel with high strength and high ionic conductivity according to claim 1, characterized in that: The mass ratio of the glyoxal grafted polyacrylamide solution to the boric acid aqueous solution is (3-9):(2-8), and the concentration of boric acid in the boric acid aqueous solution is 2 wt %-6 wt %.

7. The method for preparing a hydrogel with high strength and high ionic conductivity according to claim 1, wherein: In step S1, the grafting reaction is carried out under the following conditions: stirring at 100-300 rpm for 1-5 hours at 25-45°C.

8. The method for preparing a hydrogel with high strength and high ionic conductivity according to claim 1, characterized in that: In step S2, the reaction temperature is 10-50° C., and the reaction time is 1.5-5 h; the heating temperature is 30-70° C., and the reaction time is 1-5 h.

9. A hydrogel with high strength and high ionic conductivity prepared by the method according to any one of claims 1 to 8.

10. Use of the high-strength and high-ionic-conductivity hydrogel prepared by the method according to any one of claims 1 to 8 in the preparation of flexible wearable devices, drug carriers or biological tapes.

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