Glycerol-modified polyvinyl alcohol hydrogel and preparation method and application thereof

Abstract

The application belongs to the technical field of hydrogel materials, and particularly relates to a preparation method of glycerol-modified polyvinyl alcohol hydrogel. The microcrystalline state of the PVA hydrogel is regulated by the glycerol content in the hydrogel formula and the drying temperature, so that the mechanical properties of the PVA hydrogel are significantly improved, and the water resistance is improved. The preparation method of the application not only simplifies the traditional freeze-thaw preparation method of the PVA hydrogel, but also significantly improves the poor mechanical properties such as low stiffness, low tensile strength and low toughness of the traditional PVA hydrogel, and can widen the application range of the PVA hydrogel material. The hydrogel prepared by the preparation method of the application is simple, environment-friendly, has strong mechanical properties, good water resistance, and wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of hydrogel film materials, and particularly relates to glycerol-modified polyvinyl alcohol hydrogel and a preparation method and application thereof. BACKGROUND

[0002] Hydrogel is a typical "soft wet" material with a three-dimensional cross-linked network structure, which can absorb a large amount of water while still maintaining its solid shape. Hydrogel can be prepared from synthetic polymers such as polyvinyl alcohol, polyacrylamide, polyacrylic acid, or from natural polymers such as cellulose, chitosan and starch. Hydrogel is widely used in the fields of biology, food and electronic devices, but because most of the hydrogel preparation processes are complex and the mechanical properties are poor, which seriously limits the application of hydrogel, therefore, the preparation process for improving the mechanical properties of hydrogel has always been a research hotspot in the scientific and industrial circles.

[0003] Polyvinyl alcohol (PVA) is a biodegradable, non-carcinogenic, non-toxic, biocompatible, water-soluble and inexpensive polymer, which has good physical properties such as good transparency, low interfacial tension and high swelling rate, and is a commonly used hydrogel matrix. Most studies obtain physically cross-linked PVA hydrogel by freeze-thaw method. However, PVA hydrogel has the problem of poor mechanical strength (<15 MPa), and the freeze-thaw method consumes a lot of energy and takes a long time, which is not conducive to large-scale industrial production. SUMMARY

[0004] The purpose of the present application is to provide a method for preparing PVA hydrogel with high mechanical properties in a green, simple and low-cost manner.

[0005] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0006] Glycerol is used to adjust the network structure and the number and morphology of crystal regions of PVA, and high-temperature conditions are used to increase the intermolecular interaction force through efficient water removal and non-enzymatic caramelization, so as to improve the mechanical properties of PVA hydrogel.

[0007] According to the glycerol-modified polyvinyl alcohol hydrogel of the embodiment of the present application, the polyvinyl alcohol hydrogel is prepared by a method comprising the following steps:

[0008] (1) polyvinyl alcohol matrix and glycerol are respectively added to water, heated and stirred to dissolve, to obtain a mixed solution,

[0009] (2) the mixed solution obtained in step (1) is cast into a film and dried to obtain a thin film;

[0010] (3) the thin film obtained in step (2) is dried at 110-140℃ under a vacuum degree of 0-0.3 atm.

[0011] (4) The film dried in step (3) is placed in deionized water and soaked to obtain a polyvinyl alcohol hydrogel.

[0012] According to the polyvinyl alcohol hydrogel modified by glycerol in the embodiment of the present application, in step (1), the polyvinyl alcohol substrate and glycerol are respectively added to water, heated at 110-130°C for 10-30 minutes, and then stirred at 500-800 r / min and 65-85°C until the particles are completely dissolved, and the air bubbles are removed by ultrasonic.

[0013] According to the polyvinyl alcohol hydrogel modified by glycerol in the embodiment of the present application, in step (1), the raw materials are used in the following amounts: the polyvinyl alcohol substrate has a mass content of 4-10 wt% and the glycerol has a volume percentage content of 2-5% relative to water.

[0014] According to the polyvinyl alcohol hydrogel modified by glycerol in the embodiment of the present application, in step (3), the film is placed in a vacuum drying oven at 120°C and dried for 12 hours under a vacuum degree of 0-0.1 atm.

[0015] The preparation method of the polyvinyl alcohol hydrogel modified by glycerol according to the embodiment of the present application comprises the following steps:

[0016] (1) The polyvinyl alcohol substrate and glycerol are respectively added to water, heated, stirred and dissolved to obtain a mixed solution;

[0017] (2) The mixed solution obtained in step (1) is cast into a film, dried to obtain a film;

[0018] (3) The film obtained in step (2) is dried at 110-140°C and a vacuum degree of 0-0.3 atm;

[0019] (4) The film dried in step (3) is placed in deionized water and soaked to obtain a polyvinyl alcohol hydrogel.

[0020] The preparation method of the polyvinyl alcohol hydrogel modified by glycerol according to the embodiment of the present application, in step (1), the polyvinyl alcohol substrate and glycerol are respectively added to water, heated at 110-130°C for 10-30 minutes, and then stirred at 500-800 r / min and 65-85°C until the particles are completely dissolved, and the air bubbles are removed by ultrasonic.

[0021] In step (1), the raw materials are used in the following amounts: the polyvinyl alcohol substrate has a mass content of 4-10 wt% and the glycerol has a volume percentage content of 1-5 wt% relative to deionized water.

[0022] Still another object of the present application is to provide a glycerol-modified polyvinyl alcohol hydrogel "doped" with chitosan.

[0023] The glycerol-modified polyvinyl alcohol hydrogel according to the embodiment of the present application is prepared by a method comprising the following steps:

[0024] (1) adding a polyvinyl alcohol substrate, glycerol and chitosan into water respectively, heating, stirring and dissolving to obtain a mixed solution;

[0025] (2) casting the mixed solution obtained in step (1) into a film, drying to obtain a thin film;

[0026] (3) drying the thin film obtained in step (2) at 110-140°C under a vacuum degree of 0-0.3 atm;

[0027] (4) immersing the thin film dried in step (3) in deionized water to obtain a polyvinyl alcohol hydrogel.

[0028] In step (1) of the glycerol-modified polyvinyl alcohol hydrogel according to the embodiment of the present application, the polyvinyl alcohol substrate, glycerol and chitosan are added into water respectively, heated at 110-130°C for 10-30 minutes, then stirred at a speed of 500-800 r / min at 65-85°C until the particles are completely dissolved, and ultrasonic is used to remove air bubbles.

[0029] In step (1) of the glycerol-modified polyvinyl alcohol hydrogel according to the embodiment of the present application, the mass content of the polyvinyl alcohol substrate is 4-10 wt% relative to water, the volume percentage content of glycerol is 2-5%, and the mass content of chitosan is 0.1-0.2 wt%.

[0030] In step (1) of the glycerol-modified polyvinyl alcohol hydrogel according to the embodiment of the present application, 0.3-1 wt% of a cosolvent is added into water. The cosolvent can be selected from acetic acid, and the present application can also use citric acid, oxalic acid, succinic acid, malic acid, adipic acid.

[0031] In step (1) of the glycerol-modified polyvinyl alcohol hydrogel according to the embodiment of the present application, a modified biopolymer chitosan substrate can also be added into water, and proteins, cellulose, starch, agarose and konjac gum can be used instead.

[0032] In step (3) of the glycerol-modified polyvinyl alcohol hydrogel according to the embodiment of the present application, the thin film is dried in a vacuum drying oven at 120°C under a vacuum degree of 0-0.1 atm for 12 h.

[0033] The glycerol modified polyvinyl alcohol hydrogel prepared by the method can be applied in the fields of biological medicine, food and electrical devices.

[0034] The present application has the following advantages:

[0035] The present application uses glycerol as a modifier to adjust the internal cross-linking structure of the polyvinyl alcohol hydrogel, forms a network structure that effectively enhances the intermolecular force, significantly improves the mechanical properties of the hydrogel, and improves the water resistance, wherein the tensile strength of the hydrogel with pure polyvinyl alcohol as the substrate can reach 26.31±0.27Mpa, and the swelling rate is 56.44±2.01%, and the tensile strength of the hydrogel with chitosan mixed into the polyvinyl alcohol as the substrate can reach 27.99±1.40MPa, and the swelling rate is 81.18±4.42%.

[0036] The method of the present application does not use the traditional freeze-thaw method with high energy consumption and difficult to mass-produce, but uses the method of heating and glycerol adjustment to prepare the PVA hydrogel, which reduces the energy consumption, saves the time, and is suitable for industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description only some embodiments of the present application.

[0038] Figure 1 The mechanism diagram of the polyvinyl alcohol hydrogel of the present application is shown in the figure.

[0039] Figure 2 PVA6-Gl with different glycerol addition amounts is shown in the figure. x The microstructure SEM images of the hydrogel film are shown in the figure, wherein PVA6-Gl0(a), PVA6-Gl1(b), PVA6-Gl2(c), PVA6-Gl3(d), PVA6-Gl4(e);

[0040] Figure 3 PC-Gl is shown in the figure. x The cyclic tension diagram of the hydrogel film is shown in the figure, (a) PC-Gl2, (b) PC-Gl3, (c) PC-Gl4;

[0041] Figure 4 PC-Gl is shown in the figure. x The SEM images of the hydrogel film are shown in the figure, PC-Gl0(a), PC-Gl1(b), PC-Gl2(c), PC-Gl3(d), PC-Gl4(e), PC-G l5(f). DETAILED DESCRIPTION

[0042] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described in detail below. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work belong to the scope of protection of the present application.

[0043] The reaction principle of the present application is as follows: polyvinyl alcohol matrix and glycerol are respectively added to water, heated, stirred and dissolved to obtain a PVA-glycerol mixed solution, the mixed solution is cast into a film, dried at high temperature, and water is removed to obtain a dried film. The dried film is soaked in deionized water, and the glycerol is removed to obtain a polyvinyl alcohol hydrogel.

[0044] The present method can adjust the network structure, crystal region morphology and quantity of PVA by changing the amount of glycerol in the hydrogel formula, efficiently remove water under high temperature conditions, and promote the formation of hydrogen bonds between PVA molecules and enhance the intermolecular interaction force, as shown in FIG. 1. Therefore, the amount of glycerol and the high-temperature drying temperature can regulate the microcrystalline state of the PVA hydrogel, thereby significantly improving the mechanical properties and water resistance of the PVA hydrogel. Figure 1

[0045] The present application will be described below through specific examples.

[0046] For the sake of simplicity, the embodiments of the present application use the abbreviation PVAx-Gly to designate polyvinyl alcohol-based hydrogels modified only with glycerol, wherein x represents the mass percentage of PVA relative to water, such as x = 2%, 4%, 6%, 8%, 10%, and y represents the volume percentage of glycerol relative to water, such as 0%, 1%, 2%, 3%, 4%;

[0047] PC-Glx designates polyvinyl alcohol / chitosan hydrogel, wherein x represents the volume percentage of glycerol relative to water, such as x = 0%, 1%, 2%, 3%, 4%, 5%.

[0048] Example 1: Preparation of hydrogel PVA x -Gl y

[0049] Taking PVA6-Gl3 as an example, the preparation method thereof includes the following steps:

[0050] ​(1) take PVA 12.0 g, glycerol 6 mL, deionized water 200 mL into a pressure-resistant bottle, shake well, heat at 120℃ under high temperature and high pressure for 20 min, transfer to a magnetic stirrer and stir at 80℃ until the particles are completely dissolved, then ultrasonic defoaming, remove impurities with a pipette, obtain a mixed solution;

[0051] (2) pour the mixed solution into a plastic square (24 cm x 24 cm) flat mold, cool at room temperature for 48-72 h to form;

[0052] (3) place the prepared film into a vacuum drying oven to dry, obtain a dry film;

[0053] (4) after drying, take out and cool, then put into water, change water every 24 h, soak for 72 h, obtain hydrogel PVA6-Gl3.

[0054] Example 2: Preparation of hydrogel PC-Gl x

[0055] The preparation method of the hydrogel PC-Gl2 of the application comprises the following steps:

[0056] (1) take chitosan 0.25 g, polyvinyl alcohol 12.3 g, glycerol 2 mL, acetic acid 0.925 mL, deionized water 200 mL into a pressure-resistant bottle, heat at 120℃ for 20 min, then transfer to a magnetic stirrer and stir at 80℃ for 1 h until the particles are completely dissolved, ultrasonic defoaming, obtain a mixed solution;

[0057] (2) pour the mixed solution into a plastic square flat mold, cool at room temperature for 72 h to form;

[0058] (3) place the prepared film into a vacuum drying oven (120℃, vacuum degree 0.1 atm) for 12 h to obtain a dry film;

[0059] (4) after vacuum drying, take out and cool, then put into water, change water every 24 h, soak for 72 h, obtain a hydrogel.

[0060] Example 3: Performance test of hydrogel

[0061] 3.1 Mechanical property test

[0062] The hydrogel films were cut into specified shapes by using an electric puncher. The thickness of the hydrogel films was measured by using a micrometer (accuracy ≤ 1 um). The average thickness value was obtained by repeating the measurement for 5 times at different positions of each test sample. The mechanical properties (tensile strength TS, elongation at break E, Young's modulus YM) of the hydrogel films were measured by using a microcomputer controlled electronic universal testing machine according to GB / T 1040.3-2006. The strain rate was kept at 500 mm / min during the experiment. The final results were obtained by repeating the measurement for each sample in triplicate and taking the average value of the three groups.

[0063] 3.1.1 Hydrogel PVA x -Gl y

[0064] (1) Effect of treatment temperature

[0065] The hydrogel PVA6-Gl3 was prepared according to the method of Example 1, except that the treatment temperature in the treatment step (3) was selected as 60℃, 80℃, 100℃, 120℃ and 140℃, respectively. The results are as follows:

[0066] Table 1 Mechanical properties of PVA6-Gl3 hydrogel films under different treatment temperatures

[0067]

[0068] Note: Different letters in the same table indicate significant differences (n = 3, P < 0.05)

[0069] As can be seen from the above table, with the increase of the treatment temperature, the maximum force, tensile strength and energy at maximum force of PVA6-Gl3 hydrogel showed a trend of first increasing and then decreasing. The peak value appeared at 120℃, and the tensile strength reached 26.31 ± 0.27 MPa, and the energy at maximum force was 4859.72 ± 753.92 N x mm. The increase of temperature may accelerate the dehydration of the film and promote the formation of hydrogen bonds between PVA molecules. The presence of glycerol can effectively regulate the size, morphology and quantity of the crystal region formed between PVA molecules. At 120℃, the network structure between PVA molecular chains is most conducive to the mechanical properties in the presence of glycerol. However, when the temperature continues to rise to 140℃, the mechanical properties of PVA6-Gl3 hydrogel decrease, and the breaking tensile strain decreases to 265.96 ± 26.84%. This is because the glycerol in the structure of PVA6-Gl3 hydrogel also evaporates under the condition of long-term high temperature, and with the decrease of glycerol, the network structure between PVA molecules changes, and the mechanical properties change.

[0070] (2) Effect of treatment time

[0071] PVA6-Gl3 hydrogels were prepared according to the method of Example 1, except that the treatment time in step (3) was chosen to be 0.5 h, 1 h, 2 h, 4 h, 6 h, 8 h, 10 h, 12 h, respectively.

[0072] Table 2 Mechanical properties of PVA6-Gl3 hydrogel films with different treatment time

[0073]

[0074] Note: Different letters in the same column indicate significant differences (n = 3, P < 0.05)

[0075] From the above table, it can be seen that the mechanical properties of PVA6-Gl3 hydrogels increase with increasing treatment time. When the drying time is 12 h, the tensile strength and energy at maximum force of the gel reach a peak, because the extension of the drying time removes water more efficiently, allowing the crystallites in the hydrogel network structure to have sufficient time to form, the hydrogen bond combination increases, the intermolecular force increases, and the network structure of the gel becomes more and more dense.

[0076] (3) Effect of PVA addition amount

[0077] PVA-Gl3 hydrogels were prepared according to the method of Example 1, except that the addition amount of PVA was chosen to be 2%, 4%, 6%, 8%, 10% by mass percentage relative to water, respectively. x

[0078] Table 3 Mechanical properties of PVA-Gl3 hydrogel films x

[0079]

[0080] Note: Different letters in the same column indicate significant differences (n = 3, P < 0.05)

[0081] The above table shows the tensile strength, tensile strain at break, tensile elastic modulus, and energy at maximum force of PVAx-Gl3 hydrogel films dried at 120°C for 1 h with different PVA addition amounts. PVA6-Gl3 hydrogel tensile strength shows a maximum value of 19.82 ± 0.90 MPa. Under the same conditions, the increase in PVA content increases the intermolecular and intramolecular hydrogen bonds, and the intermolecular force is enhanced, improving the mechanical properties of PVAx-Gl3 gel. However, as the PVA content continues to increase, the mechanical properties of PVA-Gl3 show a downward trend, which is due to the increase in the concentration of PVA solution in the system, the increase in PVA molecular chains, the increase in intermolecular force, and the increase in resistance to motion, which makes the PVA x -Gl3 gel more difficult to form a network structure. x ​​-Gl3 solution viscosity increases, the formation of crystal region is hindered, so that the three-dimensional network structure of the gel is unstable. In addition, with the increase of the amount of PVA, the amount of glycerol decreases, and the decrease of glycerol may affect the size, shape and number of crystal regions formed in the intermolecular network of PVA, thereby affecting the mechanical properties of the hydrogel.

[0082] (4) The amount of glycerol added

[0083] According to the method of Example 1, the hydrogel PVA6-Gl y The amount of glycerol added is selected as 0%, 1%, 2%, 3%, and 4% by volume.

[0084] Table 4 PVA6-Gl y Mechanical properties of hydrogel films

[0085]

[0086] Note: Different letters marked in the same table show significant differences (n = 3, P < 0.05)

[0087] The above table shows that PVA6-Gl y The tensile strength, tensile strain at break, tensile elastic modulus and energy at maximum force of the hydrogel film dried at 120°C for 12h. With the increase of glycerol content, PVA6-Gl y The tensile strength and energy at maximum force of the hydrogel film show a trend of first increasing and then decreasing, and PVA6-Gl3 hydrogel shows the maximum tensile strength and energy at maximum force. Compared with traditional hydrogels (tensile strength of 0.2-10MPa), PVA6-Gl y The hydrogel is more tough and elastic, and has excellent mechanical properties, and the tensile strength of PVA6-Gl3 can reach 26.31±0.27MPa, and the energy at maximum force is 4859.72±753.92N×mm.

[0088] Table 5 Swelling properties of PVA6-Glx hydrogel film

[0089]

[0090] Note: Different letters marked in the same table show significant differences (n = 3, P < 0.05)

[0091] As can be seen from the data in the above table, after drying at 120°C for 12h, with the increase of glycerol content, PVA6-Gl yThe swelling ratio of the hydrogel showed a clear downward trend. The reason for this was that the addition of glycerol caused the formation of small crystal regions in the structure of the PVA gel, and the distribution of the crystal regions was extremely dense, making the network more dense and the gap between the grids smaller, so that a large number of water molecules could not diffuse, thus showing a gradual downward trend in the swelling ratio.

[0092] (5) Scanning Electron Microscope (SEM)

[0093] Cut 25mm 2 (5mm x 5mm) square size of the hydrogel was placed in liquid nitrogen for 30 min, and after freeze-drying treatment for 24 h, gold spraying was performed for 1 min, and the surface microstructure of the sample was observed under a scanning electron microscope (SEM) in an argon environment.

[0094] As shown in Figure 2 , it can be seen that the surface of the hydrogel is smooth, without pores and other hole structures, and the addition of glycerol is conducive to the formation of a stable and dense three-dimensional network structure of the hydrogel, which also verifies that the addition of glycerol can significantly improve the mechanical properties. Most of the PVA hydrogels prepared by the freeze-thaw method reported in the literature have a large number of pores on the surface, which is also a reason for the reduction in mechanical properties.

[0095] 3.1.2 PC-Gl x Mechanical properties of the hydrogel

[0096] (1) Effect of glycerol addition

[0097] According to the method of Example 2, the hydrogel PC-Gl x was prepared, and the addition amount of glycerol was selected to be 0%, 1%, 2%, 3%, 4%, and 5% by volume.

[0098] Table 6 PC-Gl x Mechanical properties of the hydrogel film

[0099]

[0100] The above table shows the tensile strength, tensile strain at break, and tensile elastic modulus of the hydrogel film with different glycerol contents. With the increase of the glycerol content, the tensile strength of the PC-Gl x hydrogel film showed a trend of first increasing and then decreasing, and the tensile strength of the PC-Gl3 hydrogel showed a peak value. Compared with the general hydrogels (tensile strength of 0.2-10 MPa) recorded in the literature, the PC-Gl3 hydrogel showed excellent mechanical properties, with a tensile strength of 27.99±1.40 MPa. Glycerol is likely to have some physical or chemical effect during the high-temperature vacuum drying process, affecting the network structure of PVA and CS and the mechanical action between molecules.

[0101] Table 7 PC-Gl x Swelling properties of hydrogel films

[0102]

[0103] Note: Different letters in the same table indicate significant differences (n = 3, P < 0.05)

[0104] PC-Gl prepared by high temperature 120°C vacuum drying x After the hydrogel films were air-dried, dehydrated, and then re-soaked in water for 24 h to balance, it was found from Table 6 that, with the increase of glycerol content, PC-Gl x The swelling rate of the hydrogel showed a downward trend. This is because as the amount of glycerol added increases, the cross-linked network of PVA and CS becomes denser, the gap between the grid becomes smaller, and the associated water molecules decrease, so the swelling rate gradually decreases, and the water resistance of the film is significantly improved.

[0105] (2) Analysis of cyclic tensile data

[0106] The hydrogels PC-Gl2, PC-Gl3, and PC-Gl4 were cut into uniform shapes using an electric tablet machine, the thickness of three positions was measured and averaged, and the tensile machine was set to stretch at a rate of 50%, 100%, 200%, 250%, and 300% for five cycles.

[0107] The results are shown in Table 7 PC-Gl Figure 3 The mechanical properties of the above three hydrogel films were good, but during the five cycles of stretching at elongation rates of 50%, 100%, 200%, 250%, and 300%, the PC-Gl3 hydrogel film showed better mechanical properties than the other two groups during the cyclic stretching process, which was consistent with the tensile strength results in the above mechanical property test. This phenomenon indicates that relative to the deionized water, the glycerol with a volume percentage of 3% is the optimal content, and the glycerol enhances the dynamic chemical bond effect. The covalent bonds generated by chitosan within the hydrogel network structure and the dynamic chemical bonds between the enhanced molecular network structure of glycerol make the hydrogel show good mechanical strength. The strain values shown by the abscissa in the cyclic stretching process of the three films did not return to zero, which is because during the continuous cyclic stretching process, the dynamic chemical bonds are broken more and the reformation process is slower, so the hydrogel cannot immediately recover the deformation during the cyclic stretching process.

[0108] (3) Scanning electron microscope (SEM)

[0109] The 5mm*5mm size hydrogel was placed in liquid nitrogen for 20min, and after freeze-drying treatment for 24h, the sample surface was sprayed with gold for 1min, and the sample surface microstructure was observed by scanning electron microscope (SEM) in argon environment, and the magnification was 5000 times.

[0110] PC-Gl x The ice crystals in the hydrogel network structure were sublimated by freeze-drying process, and the internal morphology structure and molecular chain crosslinking structure of the hydrogel film were observed. Figure 4 It can be seen from the SEM of the gel film that the non-obvious pore structure, which again indicates that the addition of glycerol is beneficial to the generation of the dense structure of the hydrogel. This shows that the PVA is used as the primary structure network, the chitosan is used as the secondary structure network, the networks are staggered, and with the addition of glycerol, the crosslinking of the molecular network is enhanced, and the amide covalent bond formed by the chitosan is also enhanced, so that the molecular network of the hydrogel presents a dense structure, which also leads to the reduction of the swelling rate. Glycerol generally plays a role in weakening the interaction force between molecules, but under high temperature and vacuum, it plays a certain role in the crystallization of PVA chains.

[0111] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited to this, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A glycerol-modified polyvinyl alcohol hydrogel, characterized in that, The polyvinyl alcohol hydrogel is prepared by a method comprising the following steps: (1) adding polyvinyl alcohol matrix, glycerol and chitosan into water respectively, heating, stirring and dissolving to obtain a mixed solution, (2) casting the mixed solution obtained in step (1) into a film, drying to obtain a thin film; (3) drying the thin film obtained in step (2) under the conditions of 110-140℃ and vacuum degree of 0-0.3atm; (4) soaking the dried thin film in step (3) in deionized water to obtain a polyvinyl alcohol hydrogel; In step (1), after adding polyvinyl alcohol matrix, glycerol and chitosan into water respectively, heating at 110-130℃ for 10-30 minutes, stirring at a speed of 500-800r / min and 65-85℃ until the particles are completely dissolved, and ultrasonic removal of air bubbles; The mass content of polyvinyl alcohol matrix is 4-10wt%, the volume percentage of glycerol is 2-5%, and the mass content of chitosan is 0.1-0.2wt% relative to water; In step (1), 0.3-1wt% of a cosolvent is added to water; The cosolvent is acetic acid.

2. The glycerol-modified polyvinyl alcohol hydrogel according to claim 1, characterized in that, In step (3), the thin film is placed in a vacuum drying oven at 120℃, vacuum degree of 0-0.1atm, and dried for 12h.

3. Use of the glycerol-modified polyvinyl alcohol hydrogel according to any one of claims 1-2 in the field of biomedicine, food or electrical devices.

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