Self-repairing method of PVA-based hydrogel

Abstract

The invention relates to the technical field of hydrogel self-repairing, in particular to a PVA-based hydrogel self-repairing method which comprises the following steps: correspondingly splicing PVA-based hydrogel in a mold along a fracture position and then fixing the PVA-based hydrogel in the mold; carbon fiber powder is taken and evenly scattered at the splicing fracture position of the PVA-based hydrogel; putting the mold into a microwave generating device, adjusting the microwave power to a set value, and starting the microwave generating device; when the electric spark phenomenon is observed through a transparent window of the microwave generating device, the mold is taken out of the microwave generating device; and taking out the PVA-based hydrogel, carrying out physical crosslinking again in a low-temperature environment, and unfreezing in a room-temperature environment to obtain the repaired PVA-based hydrogel. By adopting the steps, the repaired PVA-based hydrogel has the tensile strength superior to that of original PVA-based hydrogel, the microwave process is ended by observing the electric spark phenomenon, and the phenomenon of excessive repair damage caused by lack of monitoring means can be effectively avoided.

Description

Technical Field

[0001] The invention relates to the technical field of hydrogel self-repairing, and in particular to a self-repairing method of a PVA-based hydrogel. Background Art

[0002] As a typical flexible polymer material, hydrogel has many superior properties such as high water content, insolubility in water, porosity and flexibility, making it closer to natural biological tissues. It has become a highly promising advanced material in the fields of life sciences. In addition, due to its high designability of structure and function, it provides rich possibilities for its application in the field of bionic devices. Therefore, it plays an increasingly important role in cutting-edge technologies such as soft robots, artificial skin, wearable electronic devices and biomedicine. Hydrogel composites based on polyvinyl alcohol (PVA) are typical representatives of this. PVA-based composite hydrogels can be obtained by adding a reinforcing phase and repeatedly freezing and thawing. The hydrogel composites prepared in this way have good mechanical properties and biocompatibility.

[0003] At present, there are many studies on the mechanical properties of PVA-based hydrogel materials, but there are fewer studies on the repair of this material after damage under certain conditions and the monitoring of the repair process. Most of the existing repair studies are self-repairing with a small number of cross-linking times. After multiple cross-linkings form a stable network, the damaged gel cannot be repaired, and the repair process cannot be monitored. Summary of the invention

[0004] The purpose of the present invention is to provide a self-repair method for PVA-based hydrogel. The repaired PVA-based hydrogel has a tensile strength better than that of the original PVA-based hydrogel. The microwave process is terminated by observing the electric spark phenomenon, which can effectively avoid the occurrence of excessive repair damage due to lack of monitoring means.

[0005] To achieve the above object, the present invention provides a self-repairing method for a PVA-based hydrogel, comprising the following steps: S1, splicing the PVA-based hydrogel along the fracture in the mold, and then fixing the PVA-based hydrogel in the mold; S2, take carbon fiber powder and sprinkle it evenly on the splicing and breaking parts of the PVA-based hydrogel; S3, placing the mold into the microwave generator, adjusting the microwave generator to a set value, and turning on the microwave generator; S4. When electric sparks are observed through the transparent window of the microwave generator, the mold is taken out of the microwave generator; S5. Take out the PVA-based hydrogel from the mold taken out in S4, re-perform physical cross-linking in a low-temperature environment, and obtain the repaired PVA-based hydrogel after thawing in a room temperature environment.

[0006] Preferably, in S2, the carbon fiber powder is carbon fiber powder that is easily coupled with microwaves.

[0007] Preferably, in S3, the setting value is that the microwave power is 3 kW and the microwave frequency is 2.45 GHz.

[0008] Preferably, in S5, the low temperature environment is stored at -25°C for 22 h.

[0009] Preferably, in S5, the room temperature environment is stored at 25° C. for 2 h.

[0010] Mechanism of the present invention: By using the heat generated by the externally added short carbon fibers that are easy to couple with microwaves during the microwave coupling process, some hydrogen bonds in the PVA-based hydrogel at the break are opened, and then the hydrogen bonds at the break are reconnected through physical cross-linking to complete the self-repair of the PVA-based hydrogel.

[0011] Therefore, the present invention adopts a PVA-based hydrogel self-repairing method of the above steps, and its beneficial effects are: 1. The PVA-based hydrogel repaired by the self-repairing method provided by the present invention has a tensile strength superior to that of the original PVA-based hydrogel; 2. The self-repair method provided by the present invention terminates the microwave process by observing the electric spark phenomenon, which can effectively avoid the phenomenon of excessive repair damage caused by lack of monitoring means. At the same time, since the heat distribution in the coupling process is relatively concentrated, it will not cause damage to other intact areas; 3. The self-repairing method provided by the present invention is applicable to other PVA-based hydrogels prepared with PVA as the matrix through physical cross-linking.

[0012] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a schematic diagram of the PVA-based hydrogel before and after repair in Example 2 of the present invention, in, Figure 1 a in the figure is a schematic diagram of the PVA-based hydrogel before repair. Figure 1 b is a schematic diagram of the repaired PVA-based hydrogel; Figure 2 is a schematic diagram of step S4 in embodiment 2 of the present invention; Figure 3 is a graph of the tensile strength of the PVA-based hydrogel before and after repair in the present invention; Figure 4 It is a schematic diagram of the interior of the microwave generating device in Example 2 of the present invention.

[0014] Reference numerals 1. Microwave generating device; 2. Microwave tube; 3. Thermal insulation material; 4. Mould; 5. Carbon fiber powder. DETAILED DESCRIPTION

[0015] The present invention is further described below in conjunction with the accompanying drawings and embodiments. Unless otherwise defined, the technical terms or scientific terms used in the present invention should be the common meanings understood by people with ordinary skills in the field to which the present invention belongs. The above-mentioned features or features mentioned in the specific examples mentioned in the present invention can be combined arbitrarily, and these specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0016] Example 1 The preparation method of PVA-based hydrogel comprises the following steps: S1. Pour a certain amount of ionized water into a beaker, and place the beaker on a heating stirrer filled with silicone oil for heating and stirring.

[0017] S2. When the internal temperature of the beaker reaches 90°C and stabilizes, add the weighed polyvinyl alcohol.

[0018] S3. After being fully stirred in an oil bath at 90 °C for 3 h, polyvinyl alcohol was poured into the mold for preparing PVA-based hydrogel.

[0019] In S3, the total length of the PVA-based hydrogel prepared by the mold was 50 mm, and the size of the effective stretching section was 16 × 5 × 2.5 mm.

[0020] S4. Place the mold in S3 in a refrigerator at -25°C for 22 h.

[0021] S5. Take the mold in S4 out of the refrigerator and store it in an oven at 25°C for 2 h to obtain a PVA-based hydrogel.

[0022] S6. Destroying the structure of the PVA-based hydrogel to obtain a broken PVA-based hydrogel.

[0023] Example 2 The self-repairing method of the broken PVA-based hydrogel in Example 1 comprises the following steps: S1, such as Figure 1 As shown in a, the PVA-based hydrogel is spliced ​​along the fracture in the mold, and then the PVA-based hydrogel is fixed in the mold.

[0024] S2, taking carbon fiber powder 5 and evenly sprinkling it on the splicing and breaking parts of the PVA-based hydrogel; In S2, the carbon fiber powder is carbon fiber powder 5 that is easily coupled with microwaves.

[0025] S3, such as Figure 4 As shown, the mold 4 is placed in the microwave generating device 1, the microwave generating device is adjusted to a set value, and the microwave generating device 1 is turned on.

[0026] In S3, the setting values ​​are that the microwave power is 3 kW and the microwave frequency is 2.45 GHz.

[0027] The microwave tube 2 in the microwave generating device 1 provides microwaves to the PVA-based hydrogel and carbon fiber powder inside the mold. The thermal insulation material 3 is provided to maintain a consistent temperature distribution throughout the mold during the microwave repair process.

[0028] S4, such as Figure 2 As shown, when sparks are observed at the fracture of the PVA-based hydrogel through the transparent window of the microwave generator, the mold is removed from the microwave generator. The spark phenomenon is caused by the coupling of microwaves and carbon fibers. Since a large amount of short carbon fibers are piled up to be equivalent to long carbon fibers, the long carbon fibers obtained after the short carbon fibers are piled up will produce spark discharge when they exceed a certain length during the microwave coupling process.

[0029] S5. Take out the PVA-based hydrogel from the mold taken out in S4, re-perform physical cross-linking in a low-temperature environment, and obtain the repaired PVA-based hydrogel after thawing at room temperature.

[0030] In S5, the low temperature environment is stored at -25°C for 22 h.

[0031] In S5, the room temperature environment is 25°C for 2 h.

[0032] The PVA-based hydrogel repaired in S5 is cut, and steps S1-S5 are repeated for 5 times to obtain a PVA-based hydrogel as shown in FIG. Figure 1 As shown in b.

[0033] Test Example 1 The tensile strength of the PVA-based hydrogel before breaking in Example 1 and the PVA-based hydrogel after repairing 5 times in Example 2 were tested. The results are as follows: Figure 3 As shown in the figure, it can be seen that the PVA-based hydrogel after multiple repairs still has a tensile strength that is significantly better than that of the PVA-based hydrogel before breaking. This is because after microwave treatment, some pores inside the PVA hydrogel will be reduced, thereby improving the tensile strength to a certain extent.

[0034] Therefore, the present invention adopts a self-repair method of a PVA-based hydrogel according to the above steps. The repaired PVA-based hydrogel has a tensile strength that is significantly better than that of the original PVA-based hydrogel. The microwave process is terminated by observing the electric spark phenomenon at the fracture, which can effectively avoid the occurrence of excessive repair damage due to lack of monitoring means.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A self-repairing method for a PVA-based hydrogel, characterized in that: The following steps are included: S1, splicing the PVA-based hydrogel along the fracture in the mold, and then fixing the PVA-based hydrogel in the mold; S2, take carbon fiber powder and sprinkle it evenly on the splicing and breaking parts of the PVA-based hydrogel; S3, placing the mold into the microwave generator, adjusting the microwave generator to a set value, and turning on the microwave generator; S4. When electric sparks are observed through the transparent window of the microwave generator, the mold is taken out of the microwave generator; S5. Take out the PVA-based hydrogel from the mold taken out in S4, re-perform physical cross-linking in a low-temperature environment, and obtain the repaired PVA-based hydrogel after thawing in a room temperature environment.

2. A self-repairing method for a PVA-based hydrogel according to claim 1, characterized in that: In S2, the carbon fiber powder is carbon fiber powder that is easily coupled with microwaves.

3. The self-repairing method of a PVA-based hydrogel according to claim 1, characterized in that: In S3, the microwave power is set to 3 kW and the microwave frequency is set to 2.45 GHz.

4. The self-repairing method of a PVA-based hydrogel according to claim 1, characterized in that: In S5, the low temperature environment is stored at -25°C for 22 h.

5. The self-repairing method of a PVA-based hydrogel according to claim 1, characterized in that: In S5, the room temperature environment is 25°C for 2 h.

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