Preparation method and application of nanocomposite hydrogel

Abstract

The application provides a preparation method of a nanocomposite hydrogel, comprising the following steps: S1, preparing calcium phosphotungstate sub-nanowires; S2, dispersing PVA into a mixed solution of water and ethylene glycol to obtain a PVA dispersion; S3, adding the prepared calcium phosphotungstate sub-nanowires into the PVA dispersion to obtain a mixed solution with a certain viscosity; and S4, performing gelation treatment on the mixed solution with the certain viscosity to obtain calcium phosphotungstate sub-nanowire / PVA nanocomposite hydrogel. The preparation process is simple and easy to implement. Compared with a pure PVA hydrogel, the nanocomposite hydrogel prepared by the application has higher modulus and toughness, excellent mechanical properties, and wide applicability and promotion value.

Description

Technical Field

[0001] This invention relates to the field of high-performance and functional nanocomposite hydrogels, specifically to a method for preparing nanocomposite hydrogels and their applications. Background Technology

[0002] Nanocomposite hydrogels refer to composite hydrogels constructed by adding organic / inorganic nanoparticles, nanowires, and other fillers to a soft hydrogel matrix. The addition of nanofillers can endow hydrogels with good mechanical properties. The strengthening mechanism is mainly attributed to two aspects: first, the interaction between the filler and the polymer can increase the degree of cross-linking of the gel network; second, the filler can bear part of the load and disperse the deformation force on the gel.

[0003] The type of hydrogel matrix and the types of fillers such as nanoparticles and nanowires added have a significant impact on the mechanical properties of composite hydrogels. Different application fields have different requirements for the mechanical properties of nanocomposite hydrogels. Therefore, in order to expand the application fields of nanocomposite hydrogels, it is of great significance to develop composite hydrogels with excellent mechanical properties.

[0004] The patent application "A Method for Preparing Inorganic Subnanowire / PDMS Composite Elastomer Material" (Patent Application No.: 202311334895.8) describes a technique that involves the self-assembly of inorganic subnanowires with organic materials (such as octane and cyclohexane) to form an organic gel. The PDMS and the inorganic subnanowire-organic gel are then combined to obtain a novel composite material. PDMS (polydimethylsiloxane) can be directly used for moisture-proof insulation, damping, and shock absorption, and is widely used as an insulating lubricant, shock absorber, and heat carrier. However, the inorganic subnanowire / PDMS composite elastomer material prepared by this method has a relatively low elongation at break, with a maximum of less than 10%. The application fields of organic gels with this mechanical property remain very limited. For example, materials widely used in wearable sensors, soft robots, and medical materials generally require an elongation at break of over 200%, which the organic gel prepared by patent 202311334895.8 completely fails to meet.

[0005] Therefore, developing a composite hydrogel with excellent mechanical properties and a wider range of applications is an urgent technical problem to be solved. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing nanocomposite hydrogels. The preparation method is simple, and the hydrogels obtained have high modulus and toughness, and excellent mechanical properties.

[0007] To achieve the above objectives, the present invention provides a method for preparing nanocomposite hydrogels, comprising the following steps:

[0008] (1) Preparation of calcium phosphotungstate subnanowires;

[0009] (2) Disperse PVA in a mixed solution of water and ethylene glycol to obtain a PVA dispersion;

[0010] (3) Add the sub-nanowires prepared in step (1) to the PVA dispersion in step (2), and then perform gelation treatment on the mixture to obtain calcium phosphotungstenate sub-nanowire / PVA nanocomposite hydrogel.

[0011] Furthermore, the specific steps for preparing calcium phosphotungstenate subnanowires in step (1) are as follows:

[0012] Mix 0.5–2 g of phosphotungstic acid hydrate, 0.06–0.26 g of calcium nitrate tetrahydrate, and 8–32 mL of deionized water, and stir at 300–500 rpm / min for 10 minutes to obtain a clear solution. Then, add 6–24 mL of 1-octadecene and 2–8 mL of oleylamine sequentially, and stir at 200–400 rpm / min for 8 hours to obtain a white viscous liquid. Pour the reaction product into centrifuge tubes, add 20–30 mL of cyclohexane and ethanol respectively, and centrifuge and wash 3–5 times to obtain calcium phosphotungstic acid subnanowires. Centrifuge at 8000–10000 rpm / min for 5 minutes.

[0013] Furthermore, the diameter of the calcium phosphotungsten subnanowires obtained in step (1) is 0.8–1.2 nm.

[0014] Furthermore, in step (2), the mass ratio of water to ethylene glycol is 2:1, and the mass ratio of PVA to the mixed solution of water and ethylene glycol is 1:10.

[0015] Furthermore, in step (3), the mass ratio of calcium phosphotungstenate subnanowires to PVA dispersion is 1:20 to 1:100.

[0016] Furthermore, the gelation treatment in step (3) is to place the mixed solution at -15 to -20°C for 20 to 24 hours, and then take it out and place it at room temperature for 2 to 3 hours.

[0017] This invention also provides an application of the nanocomposite hydrogel prepared by the preparation method described above in wearable electronic devices, tissue engineering, and soft robots.

[0018] The nanocomposite hydrogel of this invention, based on the biocompatibility of PVA, exhibits excellent mechanical properties due to the introduction of sub-nanowires, thus showing great application prospects in wearable electronic devices, tissue engineering, soft robotics and other fields.

[0019] Compared with the prior art, the advantages and positive effects of the present invention are:

[0020] 1. The preparation process of the present invention is simple and easy to implement.

[0021] 2. The nanocomposite hydrogel prepared by this invention has higher modulus and toughness and excellent mechanical properties compared with pure PVA hydrogel, and has wide applicability and promotion value.

[0022] The polyvinyl alcohol (PVA) network structure in the nanocomposite hydrogel serves as the matrix, providing fundamental mechanical properties. Inorganic subnanowires, due to their excellent flexibility and large aspect ratio, are used as a nano-reinforcing filler to construct a dual-network hydrogel with PVA. Numerous hydrogen bonds can form between the inorganic subnanowires, PVA, and ethylene glycol, resulting in strong interactions between the inorganic subnanowire network and the PVA network, thus giving the formed dual-network hydrogel excellent mechanical properties. With increasing subnanowire content, the interaction between the inorganic subnanowire network and the PVA network strengthens, leading to a gradual increase in the mechanical properties of the subnanowire / PVA nanocomposite hydrogel. Specifically, the PVA / Ca-POM5 exhibits a fracture stress of 0.8 MPa and an elongation at break of 650%, which is relatively high for applications such as wearable electronics and soft robotics. Attached Figure Description

[0023] Figure 1 This is a TEM image of the calcium phosphotungstenate inorganic subnanowires prepared in Example 1;

[0024] Figure 2 Comparison of tensile stress-strain curves of hydrogels prepared in Examples 1, 2, 3, and 4;

[0025] Figure 3 The graph shows a comparison of the modulus and toughness of the hydrogels prepared in Examples 1, 2, 3, and 4. Detailed Implementation

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] The technical solution of the present invention will be further explained below with reference to implementation examples.

[0028] Example 1

[0029] This embodiment provides a method for preparing a nanocomposite hydrogel, and the specific preparation steps are as follows:

[0030] S1. Preparation of calcium phosphotungstenate subnanowires;

[0031] S1-1. Mix 1.0 g of phosphotungstic acid hydrate, 0.123 g of calcium nitrate hydrate and 16 mL of deionized water and stir to form a clear solution. Then add 12 mL of 1-octadecene and 4 mL of oleylamine in sequence. Stir at room temperature and 300 rpm / min for 8 hours to obtain a white viscous liquid.

[0032] S1-2. Pour the reaction product into a centrifuge tube, add 25 mL of cyclohexane and ethanol respectively, and centrifuge and wash three times to obtain calcium phosphotungstic acid subnanowires (Ca-POM). The centrifugation speed is 10000 rpm / min and the centrifugation time is 5 min. The product obtained by centrifugation contains a small amount of cyclohexane and ethanol and is in a semi-solid state.

[0033] S2. Disperse PVA in a mixed solution of water and ethylene glycol to obtain a PVA dispersion, wherein the mass ratio of water to ethylene glycol is 2:1, and the mass ratio of PVA to the mixed solution of water and ethylene glycol is 1:10.

[0034] S3. Add the prepared sub-nanowires to the PVA dispersion to obtain a mixed solution with a certain viscosity, wherein the mass ratio of sub-nanowires to PVA dispersion is 1:100.

[0035] S4. The obtained mixed solution with a certain viscosity was placed at -20℃ for 24 hours, and then taken out and placed at room temperature for 2 hours to obtain sub-nanowire / PVA nanocomposite hydrogel, which was named PVA / Ca-POM1.

[0036] Example 2

[0037] This embodiment provides a method for preparing a nanocomposite hydrogel. The specific preparation steps are the same as in Example 1, except that the mass ratio of subnanowires to PVA dispersion is 1:40 in this embodiment. The resulting subnanowire / PVA nanocomposite hydrogel is named PVA / Ca-POM. 2.5 .

[0038] Example 3

[0039] This embodiment provides a method for preparing a nanocomposite hydrogel. The specific preparation steps are the same as in Example 1. The difference between Example 1 and Example 2 is that the mass ratio of sub-nanowires to PVA dispersion is 1:20 in this embodiment. The obtained sub-nanowire / PVA nanocomposite hydrogel is named PVA / Ca-POM5.

[0040] Example 4

[0041] This embodiment provides a method for preparing PVA hydrogel, and the specific preparation steps are as follows:

[0042] S1. Disperse PVA in a mixed solution of water and ethylene glycol to obtain a PVA dispersion, wherein the mass ratio of water to ethylene glycol is 2:1, and the mass ratio of PVA to the mixed solution of water and ethylene glycol is 1:10.

[0043] S2. Place the PVA dispersion at -20°C for 24 hours, then remove it and place it at room temperature for 2 hours to obtain PVA hydrogel, which is named PVA.

[0044] Performance testing:

[0045] TEM images of inorganic subnanowires obtained in Example 1, by Figure 1 It can be seen that inorganic subnanowires were successfully prepared. The subnanowires are arranged in a linear pattern with a diameter of about 1 nm. The characteristic size of the subnanowires is close to the diameter of polymer chains / DNA single strands. They have good flexibility and a large aspect ratio, and exhibit polymer-like properties. Therefore, they can be used as a nanofiller to self-assemble with PVA to construct nanocomposite hydrogel materials.

[0046] The hydrogels prepared in Examples 1-4 of this invention were subjected to tensile property tests. A rectangular hydrogel (50 mm long, 10 mm wide) with a thickness of 2 mm was prepared. The tensile properties of the hydrogel were tested at room temperature using a domestically produced SHIMADZU universal testing machine. During the test, the tensile speed of the sample was 20 mm / min. The test results are as follows. Figure 2 As shown, the stress-strain curve of the hydrogel was obtained. Integrating the stress-strain curve yielded the material's toughness data. The Young's modulus of the material was represented by the slope of the stress-strain curve within the 10–20% strain range. The results are shown below. Figure 3 As shown, a comparison chart of the modulus and toughness of the hydrogel is obtained. (From...) Figure 2 , 3 It is evident that nanocomposite hydrogels exhibit higher modulus and toughness compared to pure PVA hydrogels, demonstrating superior mechanical properties. With increasing subnanowire content, the interaction between the inorganic subnanowire network and the PVA network strengthens, leading to a gradual increase in the mechanical properties of the subnanowire / PVA nanocomposite hydrogel. Specifically, the PVA / Ca-POM5 exhibits a fracture stress of 0.8 MPa and an elongation at break of 650%, representing a relatively high level for applications such as wearable electronics and soft robotics.

[0047] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a nanocomposite hydrogel, characterized in that, Includes the following steps: (1) Preparation of calcium phosphotungstate subnanowires; (2) Disperse PVA in a mixed solution of water and ethylene glycol to obtain a PVA dispersion; (3) Add the sub-nanowires prepared in step (1) to the PVA dispersion in step (2), and then perform gelation treatment on the mixture to obtain calcium phosphotungstenate sub-nanowire / PVA nanocomposite hydrogel.

2. The method for preparing a nanocomposite hydrogel according to claim 1, characterized in that, The specific steps for preparing calcium phosphotungstenate subnanowires in step (1) are as follows: Mix 0.5–2 g of phosphotungstic acid hydrate, 0.06–0.26 g of calcium nitrate tetrahydrate, and 8–32 mL of deionized water, and stir at 300–500 rpm / min for 10 minutes to obtain a clear solution. Then, add 6–24 mL of 1-octadecene and 2–8 mL of oleylamine sequentially, and stir at 200–400 rpm / min for 8 hours to obtain a white viscous liquid. Pour the reaction product into a centrifuge tube, add 20–30 mL of cyclohexane and ethanol respectively, and centrifuge and wash 3–5 times to obtain calcium phosphotungstic acid subnanowires. Centrifuge at 8000–10000 rpm / min for 5 minutes.

3. The method for preparing a nanocomposite hydrogel according to claim 1, characterized in that: The diameter of the calcium phosphotungsten subnanowires obtained in step (1) is 0.8 to 1.2 nm.

4. The method for preparing a nanocomposite hydrogel according to claim 1, characterized in that: In step (2), the mass ratio of water to ethylene glycol is 2:1, and the mass ratio of PVA to the mixed solution of water and ethylene glycol is 1:

10.

5. The method for preparing a nanocomposite hydrogel according to claim 1, characterized in that: In step (3), the mass ratio of calcium phosphotungstenate subnanowires to PVA dispersion is 1:20 to 1:

100.

6. The method for preparing a nanocomposite hydrogel according to claim 1, characterized in that: The gelation treatment in step (3) is to place the mixed solution at -15 to -20°C for 20 to 24 hours, and then take it out and place it at room temperature for 2 to 3 hours.

7. The application of the nanocomposite hydrogel prepared by any one of the preparation methods according to claims 1-6 in wearable electronic devices, tissue engineering, and soft robots.

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