Carbon dot-based high-moisture-content super-strong hydrogel and preparation method thereof

Abstract

The invention discloses a carbon dot-based high-moisture-content super-strong hydrogel and a preparation method thereof, and belongs to the technical field of hydrogel materials.The preparation method comprises the steps that a carbon dot solution is prepared through a hydrothermal method and then mixed with a polyvinyl alcohol solution, an initial hydrogel network is constructed through a high-temperature reaction and a freeze-thaw cycle, and the carbon dot-based high-moisture-content super-strong hydrogel is obtained; finally, salting-out auxiliary treatment is conducted through a sodium lignin sulfonate solution. Namely, sodium lignin sulfonate carbon dots are creatively used as a multifunctional nano filler, and rich functional groups on the surface of the sodium lignin sulfonate carbon dots can form multiple physical cross-linking with PVA chains; meanwhile, sulfonate groups introduced in the salting-out process can form a unique'water lock 'structure, and the inherent contradiction between high water content and high strength is synergistically solved. The hydrogel has the advantages of high water content, ultrahigh mechanical property and excellent stability, the preparation process is green and simple, and the hydrogel has wide application prospects in the fields of flexible electronics, biomedicine and the like.

Description

Technical Field

[0001] This invention belongs to the field of hydrogel materials technology, and particularly relates to a carbon dot-based high water content super-strong hydrogel and its preparation method. Background Technology

[0002] Hydrogels, with their unique conductivity, flexibility, and three-dimensional porous structure, show great promise in fields such as flexible electronics, biomedicine, and energy storage. However, traditional hydrogels often suffer from poor mechanical properties due to their simple network structure, lack of energy dissipation mechanisms, and stress concentration effects, making it difficult to achieve both high strength and high toughness. Although some studies have improved their properties through strategies such as constructing dual networks, hybrid crosslinking, or directional freezing, few systems can simultaneously achieve a fracture strength of over 50 MPa and a tensile strength of 200 MJ / m². -3 The level of toughness, especially while maintaining a high moisture content (>70%).

[0003] In recent years, nanofillers (such as carbon nanotubes and graphene) have been introduced into hydrogels to enhance their mechanical properties. However, their compatibility with polymer matrices is poor, they are prone to aggregation, and interfacial interactions are mostly weak physical adsorption, resulting in limited reinforcing effects. Furthermore, the complex and costly preparation of these nanomaterials limits their widespread application. Carbon dots (CDs), as an emerging class of carbon nanomaterials, have attracted widespread attention since their discovery in 2004 due to their excellent optical properties, biocompatibility, and tunable surface properties; however, their application in the mechanical reinforcement of composite materials is still in its early stages.

[0004] Sodium lignosulfonate is a byproduct of the papermaking industry, abundant in resources and inexpensive. Its molecular structure is rich in functional groups such as sulfonic acid groups, phenolic hydroxyl groups, and alcoholic hydroxyl groups. Converting it into carbon dots holds promise as a high-performance, low-cost nanofiller. However, simply introducing carbon dots into hydrogel systems offers limited improvement in mechanical properties.

[0005] Therefore, there is an urgent need for a new strategy that can fully utilize the advantages of low-cost nanofillers and cleverly resolve the inherent contradiction between the high water content and high strength of hydrogels. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention proposes a carbon dot-based high-water-content superhydrogel and its preparation method.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a carbon dot-based high-water-content superhydrogel includes the following steps: (1) The sodium lignosulfonate solution was heated to prepare a carbon dot solution of sodium lignosulfonate; (2) The sodium lignosulfonate carbon dot solution is mixed with polyvinyl alcohol, heated, cooled, and then subjected to freeze-thaw cycle treatment to obtain sodium lignosulfonate carbon dot-polyvinyl alcohol hydrogel. (3) The sodium lignosulfonate carbon dot-polyvinyl alcohol hydrogel was added to the sodium lignosulfonate solution for salting out, and finally the carbon dot-based high water content super hydrogel was obtained.

[0008] Optionally, in step (1), the ratio of sodium lignosulfonate to deionized water in the sodium lignosulfonate solution is 0.5-4 g : 100 mL.

[0009] Optionally, in step (1), the temperature of the heat treatment is 140-180℃ and the time is 2-8 h.

[0010] Optionally, in step (2), the mass ratio of the sodium lignosulfonate carbon dot solution to polyvinyl alcohol is 5:1.

[0011] Optionally, in step (2), the heating conditions are: heating temperature of 95°C and heating time of 4 h.

[0012] Optionally, in step (2), the freeze-thaw cycle process is as follows: Freeze at -20℃ for 12 h, then thaw at 20℃ for 3 h, and repeat the freeze-thaw cycle 3 times.

[0013] Optionally, in step (3), the mass fraction of the sodium lignosulfonate solution is 10-40%.

[0014] Optionally, in step (3), the salting-out time is 12 h.

[0015] A carbon dot-based high-water-content superhydrogel was prepared by the above-described preparation method.

[0016] Optionally, the carbon dot-based high-water-content superhydrogel has a tensile strength of 120.52 MPa and a toughness of 32221.3 MJ / m. 3 .

[0017] Compared with the prior art, the present invention has the following advantages and technical effects: This invention uses sodium lignosulfonate carbon dots as nanofillers and combines them with the salting-out effect to synergistically construct a high-performance hydrogel system. Utilizing the sensitivity of polyvinyl alcohol to the Hofmeister effect and the "water-locking" structure formed by sulfonate groups, a hydrogel with high water content and excellent mechanical properties was successfully prepared under the combined action of carbon dots and salting-out.

[0018] To improve the mechanical properties of hydrogels, this invention discloses a reinforcement method using sodium lignosulfonate carbon dots as nanofillers combined with a salting-out assisted strategy. The carbon dots interact with the hydrogel matrix through multiple interactions, including hydrogen bonding, van der Waals forces, and π-π stacking, resulting in a synergistic effect that significantly enhances the mechanical properties of the hydrogel. Furthermore, the carbonization process effectively retains precursor functional groups, exhibiting good dispersibility and introducing numerous physical cross-linking reaction sites for the polyvinyl alcohol hydrogel. Simultaneously, the "water-locking" effect formed by the sulfonate groups achieves a significant improvement in the strength and toughness of the hydrogel while maintaining high water content. The hydrogel preparation process of this invention is simple, and the resulting hydrogel exhibits excellent performance. Attached Figure Description

[0019] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 The stress-strain curves of the hydrogels prepared in Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 of this invention are shown. Figure 2 The stress-strain curves of the hydrogels prepared in Example 1, Comparative Example 4, and Comparative Example 5 of this invention are shown. Figure 3 The stress-strain curves of the hydrogels prepared in Example 1 and Comparative Examples 6-7 of this invention are shown. Figure 4 The stress-strain curve of the hydrogel prepared in Example 2 of this invention is shown. Detailed Implementation

[0020] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0021] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0022] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0023] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This specification and embodiments are merely exemplary.

[0024] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0025] This invention provides a method for preparing a carbon dot-based high-water-content superhydrogel, comprising the following steps: (1) A carbon dot solution is prepared by using a carbon source (sodium lignosulfonate) as raw material and water as solvent, through firing (heating) and cooling. (2) Using the above carbon dot solution and polyvinyl alcohol as reactants, carbon dot-polyvinyl alcohol hydrogel was obtained by high-temperature heating reaction and freeze-thaw cycle. (3) The carbon dot-polyvinyl alcohol hydrogel obtained above is subjected to salting out to obtain carbon dot-based superhydrogel.

[0026] In some alternative embodiments, the ratio of carbon source to water is 0.5-4 g : 100 mL.

[0027] In some alternative embodiments, the firing (heating) temperature is 140-180°C and the time is 2-8 hours.

[0028] In some alternative embodiments, the mass ratio of carbon dot solution to polyvinyl alcohol is 5:1.

[0029] In some alternative embodiments, the high-temperature heating reaction is carried out at a temperature of 95°C for 4 hours.

[0030] In some alternative embodiments, the specific steps of the freeze-thaw cycle are as follows: freeze at -20°C for 12 hours, then thaw at 20°C for 3 hours, and repeat the freeze-thaw cycle three times.

[0031] In some optional embodiments, the specific steps of salting-out assistance are as follows: The carbon dot-polyvinyl alcohol hydrogel was soaked in sodium lignosulfonate solution for 12 hours.

[0032] In some alternative embodiments, the sodium lignosulfonate solution has a mass fraction of 10-40%.

[0033] During the salting-out process, the hydrogel becomes more compact, which can enhance its mechanical properties.

[0034] In summary, to improve the mechanical properties of hydrogels, this invention discloses a reinforcement method using sodium lignosulfonate carbon dots as nanofillers combined with a salting-out assisted strategy. The carbon dots interact with the hydrogel matrix through multiple interactions, including hydrogen bonds, van der Waals forces, and π-π stacking, resulting in a synergistic effect that significantly enhances the mechanical properties of the hydrogel. Furthermore, the carbonization process effectively retains precursor functional groups, exhibiting good dispersibility. Simultaneously, the "water-locking" effect formed by the sulfonate groups ensures a significant improvement in the strength and toughness of the hydrogel while maintaining high water content.

[0035] In addition, the present invention also provides a carbon dot-based high water content superhydrogel prepared by the above preparation method.

[0036] Unless otherwise specified, "room temperature" in this invention refers to 20-30℃.

[0037] All raw materials used in this invention were purchased from the market.

[0038] The technical solution of the present invention will be further illustrated by the following embodiments.

[0039] Example 1 A method for preparing a carbon dot-based high water content superhydrogel (sodium lignosulfonate carbon dot-based high water content superhydrogel), comprising the following steps: S1. Add 2g of sodium lignosulfonate to 100mL of deionized water, place it in a pressure-resistant reaction flask and heat it to 160℃ for 4h. Let the reaction container cool naturally to room temperature to obtain sodium lignosulfonate carbon dot solution. S2. A sodium lignosulfonate carbon dot solution (75g) and polyvinyl alcohol (15g) were mixed and reacted at 95℃ for 4h. After the mixed solution was cooled to room temperature, the reaction product was subjected to freeze-thaw cycle treatment (freeze-thaw cycle is freezing at -20℃ for 12h, then thawing at 20℃ for 3h, freeze-thaw repeating twice, for a total of 3 freeze-thaw cycles) to obtain sodium lignosulfonate carbon dot-polyvinyl alcohol hydrogel. S3. The sodium lignosulfonate carbon dot-polyvinyl alcohol hydrogel obtained in step S2 is soaked in a 40% sodium lignosulfonate solution for 12 hours to obtain a sodium lignosulfonate carbon dot-based high water content superhydrogel.

[0040] Example 2 A method for preparing a carbon dot-based superhydrogel with a water content of 70%, comprising the following steps: S1. Add 2g of sodium lignosulfonate to 100mL of deionized water, place it in a pressure-resistant reaction flask and heat it to 160℃ for 4h. Let the reaction container cool naturally to room temperature to obtain sodium lignosulfonate carbon dot solution. S2. A sodium lignosulfonate carbon dot solution (75g) and polyvinyl alcohol (15g) were mixed and reacted at 95℃ for 4h. After the mixed solution was cooled to room temperature, the reaction product was subjected to freeze-thaw cycle treatment (freeze-thaw cycle is freezing at -20℃ for 12h, then thawing at 20℃ for 3h, freeze-thaw repeating twice, for a total of 3 freeze-thaw cycles) to obtain sodium lignosulfonate carbon dot-polyvinyl alcohol hydrogel. S3. The sodium lignosulfonate carbon dot-polyvinyl alcohol hydrogel obtained in step S2 is soaked in a 40% sodium lignosulfonate solution for 12 hours to obtain a sodium lignosulfonate carbon dot-based high water content superhydrogel.

[0041] S4. The sodium sulfonate carbon dot-based high water content superhydrogel obtained in step S3 is placed in a 30°C oven for 4 hours to obtain a carbon dot-based superhydrogel with a water content of 70%, and the water content remains at 70% even after further drying.

[0042] Comparative Example 1 The preparation steps of a sodium lignosulfonate carbon dot-polyvinyl alcohol hydrogel are as follows: S1. Add 2g of sodium lignosulfonate to 100mL of deionized water, place it in a pressure-resistant reaction flask and heat it to 160℃ for 4h. Let the reaction container cool naturally to room temperature to obtain sodium lignosulfonate carbon dot solution. S2. A sodium lignosulfonate carbon dot solution (75g) and polyvinyl alcohol (15g) were mixed and reacted at 95℃ for 4h. After the mixed solution was cooled to room temperature, the reaction product was subjected to freeze-thaw cycle treatment (freeze-thaw cycle is freezing at -20℃ for 12h, then thawing at 20℃ for 3h, freeze-thaw repeating twice, for a total of 3 freeze-thaw cycles) to obtain sodium lignosulfonate carbon dot-polyvinyl alcohol hydrogel.

[0043] Comparative Example 2 The preparation steps of a sodium lignosulfonate-polyvinyl alcohol hydrogel are as follows: S1. Add 2g of sodium lignosulfonate to 100mL of deionized water, place in a beaker and stir at room temperature for 4h to obtain sodium lignosulfonate solution. S2. A sodium lignosulfonate solution (75g) and polyvinyl alcohol (15g) were mixed and reacted at 95°C for 4h. After the mixed solution was cooled to room temperature, the reaction product was subjected to freeze-thaw cycle treatment (freeze-thaw cycle is freezing at -20°C for 12h, then thawing at 20°C for 3h, repeating freeze-thaw twice, for a total of 3 freeze-thaw cycles) to obtain sodium lignosulfonate-polyvinyl alcohol hydrogel.

[0044] Comparative Example 3 The preparation steps of a polyvinyl alcohol hydrogel are as follows: Deionized water (75g) and polyvinyl alcohol (15g) were mixed and reacted at 95℃ for 4h. After the mixed solution was cooled to room temperature, the reaction product was subjected to freeze-thaw cycle treatment (freeze-thaw cycle is freezing at -20℃ for 12h, then thawing at 20℃ for 3h, freeze-thaw repeating twice, for a total of 3 freeze-thaw cycles) to obtain polyvinyl alcohol hydrogel.

[0045] Comparative Example 4 The preparation steps of sodium lignosulfonate carbon dots-polyvinyl alcohol hydrogel after salting out with a 10% (w / w) sodium lignosulfonate solution are as follows: S1. Add 2g of sodium lignosulfonate to 100mL of deionized water, place it in a pressure-resistant reaction flask and heat it to 160℃ for 4h. Let the reaction container cool naturally to room temperature to obtain sodium lignosulfonate carbon dot solution. S2. A sodium lignosulfonate carbon dot solution (75g) and polyvinyl alcohol (15g) were mixed and reacted at 95℃ for 4h. After the mixed solution was cooled to room temperature, the reaction product was subjected to freeze-thaw cycle treatment (freeze-thaw cycle is freezing at -20℃ for 12h, then thawing at 20℃ for 3h, freeze-thaw repeating twice, for a total of 3 freeze-thaw cycles) to obtain sodium lignosulfonate carbon dot-polyvinyl alcohol hydrogel. S3. The sodium lignosulfonate carbon dot-polyvinyl alcohol hydrogel obtained in step S2 is soaked in a 10% sodium lignosulfonate solution for 12 hours to obtain a sodium lignosulfonate carbon dot-based high water content super-strong hydrogel.

[0046] Comparative Example 5 The preparation steps of sodium lignosulfonate carbon dots-polyvinyl alcohol hydrogel after salting out with a 20% (w / w) sodium lignosulfonate solution are as follows: S1. Add 2g of sodium lignosulfonate to 100mL of deionized water, place it in a pressure-resistant reaction flask and heat it to 160℃ for 4h. Let the reaction container cool naturally to room temperature to obtain sodium lignosulfonate carbon dot solution. S2. A sodium lignosulfonate carbon dot solution (75g) and polyvinyl alcohol (15g) were mixed and reacted at 95℃ for 4h. After the mixed solution was cooled to room temperature, the reaction product was subjected to freeze-thaw cycle treatment (freeze-thaw cycle is freezing at -20℃ for 12h, then thawing at 20℃ for 3h, freeze-thaw repeating twice, for a total of 3 freeze-thaw cycles) to obtain sodium lignosulfonate carbon dot-polyvinyl alcohol hydrogel. S3. The sodium lignosulfonate carbon dot-polyvinyl alcohol hydrogel obtained in step S2 is soaked in a 20% sodium lignosulfonate solution for 12 hours to obtain a sodium lignosulfonate carbon dot-based high water content super-strong hydrogel.

[0047] Comparative Example 6 The preparation steps of sodium lignosulfonate carbon dot-based high water content superhydrogel treated at 140℃ are as follows: S1. Add 2g of sodium lignosulfonate to 100mL of deionized water, place it in a pressure-resistant reaction flask and heat it to 140℃ for 4h. Let the reaction container cool naturally to room temperature to obtain sodium lignosulfonate carbon dot solution. S2. A sodium lignosulfonate carbon dot solution (75g) and polyvinyl alcohol (15g) were mixed and reacted at 95℃ for 4h. After the mixed solution was cooled to room temperature, the reaction product was subjected to freeze-thaw cycle treatment (freeze-thaw cycle is freezing at -20℃ for 12h, then thawing at 20℃ for 3h, freeze-thaw repeating twice, for a total of 3 freeze-thaw cycles) to obtain sodium lignosulfonate carbon dot-polyvinyl alcohol hydrogel. S3. The sodium lignosulfonate carbon dot-polyvinyl alcohol hydrogel obtained in step S2 is soaked in a 40% sodium lignosulfonate solution for 12 hours to obtain a sodium lignosulfonate carbon dot-based high water content super-strong hydrogel.

[0048] Comparative Example 7 The preparation steps of sodium lignosulfonate carbon dot-based high water content superhydrogel after hydrothermal treatment at 180℃ are as follows: S1. Add 2g of sodium lignosulfonate to 100mL of deionized water, place it in a pressure-resistant reaction flask and heat it to 180℃ for 4h. Let the reaction container cool naturally to room temperature to obtain sodium lignosulfonate carbon dot solution. S2. A sodium lignosulfonate carbon dot solution (75g) and polyvinyl alcohol (15g) were mixed and reacted at 95℃ for 4h. After the mixed solution was cooled to room temperature, the reaction product was subjected to freeze-thaw cycle treatment (freeze-thaw cycle is freezing at -20℃ for 12h, then thawing at 20℃ for 3h, freeze-thaw repeating twice, for a total of 3 freeze-thaw cycles) to obtain sodium lignosulfonate carbon dot-polyvinyl alcohol hydrogel. S3. The sodium lignosulfonate carbon dot-polyvinyl alcohol hydrogel obtained in step S2 is soaked in a 40% sodium lignosulfonate solution for 12 hours to obtain a sodium lignosulfonate carbon dot-based high water content super-strong hydrogel.

[0049] Effect verification: Application example: The mechanical properties and toughness calculations of the hydrogels prepared in Examples 1-2 and Comparative Examples 1-7 were performed. The methods are as follows, and the results are shown in Table 1.

[0050] The dumbbell-shaped (75mm × 12.5mm × 2m) hydrogels prepared in Examples 1-2 and Comparative Examples 1-7 were subjected to tensile property tests at room temperature. Uniaxial tensile measurements were performed using an electronic universal testing machine (Shenzhen Suntech Power Technology Co., Ltd., China) at an elongation speed of 100mm / min.

[0051] toughness( The area under the stress-strain curve is calculated using the following formula: ; In the formula, σ and ε are the stress and strain of the hydrogel, respectively.

[0052] Table 1 As shown in Table 1, the hydrogel prepared in Example 1 exhibits the best tensile strength and toughness, reaching 120.52 MPa and 32221.3 MJ / m³, respectively. Combined with the results of Comparative Examples 1-3, it can be seen that the carbon dot-based high-water-content super-strong hydrogel prepared using sodium lignosulfonate carbon dots as nanofillers, combined with salting-out assisted treatment, significantly outperforms the control group (those with only carbon dots, those without carbon dots, and those without carbonized sodium lignosulfonate) in terms of mechanical properties. This indicates that the composite structure has a synergistic effect in enhancing the hydrogel's performance.

[0053] Figure 1 The stress-strain curves of the hydrogels prepared in Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 are shown below. Figure 1 It can be seen that, compared with hydrogels prepared without sodium lignosulfonate, uncarbonized sodium lignosulfonate, and those prepared with only carbonized sodium lignosulfonate without salting-out assistance, the salting-out-assisted sodium lignosulfonate carbon dot-based high-water-content super-strong hydrogel exhibits mechanical properties of 120.52 MPa and 32221.3 MJ / m², respectively. 3This is because sodium lignosulfonate enhances the network structure of the hydrogel by increasing ionic strength and promoting the formation of crosslinking points. Secondly, the interaction between sodium ions and the functional groups of PVA and carbon dots further improves the crosslinking density and network stability. On the other hand, in the salt solution, osmotic pressure is created inside and outside the PVA, making the PVA more compact and enhancing its mechanical properties. The mechanical properties of the sodium lignosulfonate carbon dot-polyvinyl alcohol hydrogel (Comparative Example 1) are 8.31 MPa and 1634.6 MJ / m³. 3 This is because sodium lignosulfonate carbon dots can form more cross-linking points in PVA hydrogels, making the hydrogel's network structure more stable and compact. Simultaneously, the nanoscale size and excellent dispersibility of sodium lignosulfonate carbon dots enhance the network density and cross-linking effect of the PVA hydrogel. This improved network structure can effectively disperse and withstand external loads, thereby improving tensile strength and toughness. The mechanical properties of sodium lignosulfonate-polyvinyl alcohol hydrogel (Comparative Example 2) are 7.86 MPa and 1624.83 MJ / m². 3 This represents a certain improvement in mechanical properties compared to polyvinyl alcohol hydrogel (Comparative Example 3). This is because sodium lignosulfonate can undergo a cross-linking reaction with the hydroxyl groups in PVA molecules. Sodium lignosulfonate forms cross-linking points with PVA molecules through these functional groups, which helps to form a tighter network structure, thereby improving the strength of the hydrogel. Compared to pure PVA, sodium lignosulfonate-polyvinyl alcohol hydrogel can form cross-linking points between PVA chains, enhancing the stability and strength of the network structure.

[0054] Figure 2 The stress-strain curves of the hydrogels prepared in Example 1, Comparative Example 4, and Comparative Example 5 are shown below. Figure 2 As can be seen, compared with the sodium lignosulfonate carbon dot-polyvinyl alcohol hydrogels prepared by salting out with a 10% sodium lignosulfonate solution (Comparative Example 4) and a 20% sodium lignosulfonate solution (Comparative Example 5), the lignosulfonate carbon dot-based high-water-content super-strong hydrogel prepared by salting out with a 40% sodium lignosulfonate solution (Example 1) has mechanical properties of 120.52 MPa and 32221.3 MJ / m³. This is mainly because the higher concentration of sodium lignosulfonate can form a denser cross-linked structure during the salting out process, providing stronger ionic cross-linking and a denser network, thereby significantly enhancing the tensile strength and toughness of the material.

[0055] Figure 3 The stress-strain curves of the hydrogels prepared in Example 1 and Comparative Examples 6-7 are shown below. Figure 3It can be seen that the mechanical properties of hydrogels prepared based on sodium lignosulfonate carbon dots calcined at 140 ℃, 160 ℃, and 180 ℃ increased from 53.80 MPa to 120.52 MPa and then decreased to 65.87 MPa. The carbon dots calcined at 140 ℃ had a lower degree of graphitization and more surface functional groups, but their interfacial interaction with the PVA matrix was weak, limiting the improvement of mechanical properties. The carbon dots calcined at 160 ℃ had a moderate degree of graphitization and optimized surface characteristics, which enabled them to form a stronger interfacial bond with PVA, thus significantly improving mechanical properties. However, when the temperature was further increased to 180 ℃, the carbon dots became over-graphitized or underwent structural changes, weakening their interaction with the polymer network and leading to a decline in performance.

[0056] Figure 4 Example 2 exhibits excellent overall performance, with a tensile strength of 143.42 MPa and a toughness of 28113.8 MJ / m³. This hydrogel maintains excellent mechanical strength and toughness even in a high water content state, demonstrating its promising application potential in flexible devices, biomedical materials, and other fields.

[0057] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a carbon dot-based high-water-content superhydrogel, characterized in that, Includes the following steps: (1) The sodium lignosulfonate solution was heated to prepare a carbon dot solution of sodium lignosulfonate; (2) The sodium lignosulfonate carbon dot solution is mixed with polyvinyl alcohol, heated and cooled, and then subjected to freeze-thaw cycle treatment to obtain sodium lignosulfonate carbon dot-polyvinyl alcohol hydrogel. (3) The sodium lignosulfonate carbon dot-polyvinyl alcohol hydrogel was added to the sodium lignosulfonate solution for salting out, and finally the carbon dot-based high water content super hydrogel was obtained.

2. The method for preparing a carbon dot-based high-water-content superhydrogel according to claim 1, characterized in that, In step (1), the ratio of sodium lignosulfonate to water in the sodium lignosulfonate solution is 0.5-4g : 100mL.

3. The method for preparing a carbon dot-based high-water-content superhydrogel according to claim 1, characterized in that, In step (1), the temperature of the heat treatment is 140-180℃ and the time is 2-8 h.

4. The method for preparing a carbon dot-based high-water-content superhydrogel according to claim 1, characterized in that, In step (2), the mass ratio of the sodium lignosulfonate carbon dot solution to polyvinyl alcohol is 5:

1.

5. The method for preparing a carbon dot-based high-water-content superhydrogel according to claim 1, characterized in that, In step (2), the heating conditions are: heating temperature of 95°C and heating time of 4 hours.

6. The method for preparing a carbon dot-based high-water-content superhydrogel according to claim 1, characterized in that, In step (2), the freeze-thaw cycle process is as follows: Freeze at -20℃ for 12 h, then thaw at 20℃ for 3 h, with freezing-thawing as one cycle, for a total of 3 cycles.

7. The method for preparing a carbon dot-based high-water-content superhydrogel according to claim 1, characterized in that, In step (3), the mass concentration of the sodium lignosulfonate solution is 10%-40%.

8. The method for preparing a carbon dot-based high-water-content superhydrogel according to claim 1, characterized in that, In step (3), the salting-out time is 12 h.

9. A carbon dot-based high-water-content superhydrogel, characterized in that, It is prepared by the preparation method according to any one of claims 1-8.

10. The carbon dot-based high-water-content superhydrogel according to claim 9, characterized in that, The carbon dot-based high-water-content superhydrogel has a tensile strength of 120.52 MPa and a toughness of 32221.3 MJ / m. 3 .

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