A high-performance sodium alginate / graphene double-network hydrogel and a preparation method and application thereof

Abstract

The application discloses a kind of high-performance sodium alginate / graphene double-network hydrogel and its preparation method and application, belong to the field of hydrogel.The high-performance sodium alginate / graphene double-network hydrogel, it includes the sheet layer network crosslinking formed by interface interaction of calcium lignosulfonate and graphene oxide, and by the carboxyl group of sodium alginate and the calcium ion of calcium lignosulfonate through ion exchange and form the ion crosslinking network. Among them, calcium lignosulfonate is used as dispersing agent and also as crosslinking agent, specifically, calcium lignosulfonate aqueous solution, graphene oxide aqueous solution and sodium alginate aqueous solution are mixed, and biological ink is obtained by external field force treatment;The hydrogel preform is obtained by the way of 3D printing by the biological ink;The high-performance sodium alginate / graphene double-network hydrogel is obtained by reducing treatment to the hydrogel preform.The sodium alginate / graphene double-network hydrogel has good physical strength and conductivity.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of hydrogel, and particularly relates to a high-performance sodium alginate / graphene double-network hydrogel as well as a preparation method and application thereof. BACKGROUND

[0002] The information disclosed in this Background section is for the purpose of generally presenting the context of the application. The information disclosed in this Background section is not to be taken as an acknowledgement or any form of suggestion that it constitutes prior art apre-existing concept known to those skilled in the art.

[0003] Graphene is a two-dimensional honeycomb lattice structure material stacked by single-layer carbon atoms. Due to its excellent physical properties, including excellent mechanical properties, large specific surface area, excellent thermal stability and high electrical conductivity, graphene exhibits great potential in many frontier fields such as biosensors, electromagnetic shielding, catalyst carriers and fuel cells.

[0004] Sodium alginate-based hydrogel is widely used in the fields of biosensors, electromagnetic shielding, conductive materials, etc. due to its good biocompatibility, softness and high sensitivity. At present, graphene material has been widely used as the core material in the field of sodium alginate-based hydrogel sensors. However, during the preparation of the preform by the liquid phase method, the graphene sheets are prone to agglomeration due to the strong van der Waals force between the graphene sheets, which hinders the effective transfer of load, heat and electrons of graphene, becomes an unfavorable factor in the matrix material, and reduces the physical strength and electrical conductivity of the sodium alginate-based hydrogel material.

[0005] In addition, there is a problem in sodium alginate-based hydrogel, that is, a chemical cross-linking agent usually needs to be added during the printing of the shaped object. However, the material source and composition of the cross-linking agent are relatively complex, which will affect the biodegradability and stability of the biological ink in the field of biological cells. For example, when calcium chloride is used as a cross-linking agent, there will be more residues of calcium chloride, and the calcium ions in the calcium chloride will cause damage to cells. Therefore, it is an urgent need for 3D biological printing to prepare a sodium alginate-based hydrogel material with good comprehensive performance. SUMMARY

[0006] In order to solve the problems of the prior art, the present application aims to provide a high-performance sodium alginate / graphene double-network hydrogel and a preparation method and application thereof.Calcium lignosulfonate, sodium alginate, and graphene are mixed, wherein the calcium lignosulfonate is used as a dispersant and a crosslinking agent, in the process of preparing the hydrogel, the calcium lignosulfonate is first added into an aqueous graphene oxide solution as a dispersant to avoid the agglomeration of graphene oxide, and then an aqueous sodium alginate solution is added, at this time, the calcium lignosulfonate acts as a crosslinking agent, calcium ions and carboxyl groups in the sodium alginate undergo ion exchange to form a crosslinking network, thereby forming a sodium alginate / graphene composite hydrogel with a double-network structure.The sodium alginate / graphene composite hydrogel has good physical strength and electrical conductivity.

[0007] In order to achieve the above-mentioned purposes, the technical scheme of the present application is as follows:

[0008] In the first aspect, the present application provides a high-performance sodium alginate / graphene double-network hydrogel, which comprises a sheet network crosslinked by calcium lignosulfonate and graphene oxide through interfacial interaction, and an ion crosslinking network formed by ion exchange between carboxyl groups of sodium alginate and calcium ions of calcium lignosulfonate.

[0009] The reaction mechanism is as follows: the calcium lignosulfonate first interacts with the graphene oxide, the calcium lignosulfonate acts as a dispersant, in the process of dispersing graphene, the calcium lignosulfonate mainly interacts with graphene through some functional groups in its molecular structure, such as sulfonic acid groups and hydroxyl groups, such as electrostatic interaction and π-π stacking interaction, to realize the dispersion and stabilization of graphene, prevent the agglomeration of graphene sheets, and ensure the uniform dispersion of graphene in the solution.When the sodium alginate solution is added to the mixture, the calcium lignosulfonate acts as a crosslinking agent, in the process of crosslinking the sodium alginate, some cations (such as calcium ions) in the calcium lignosulfonate and carboxyl groups in the sodium alginate undergo ion crosslinking to form a second layer of ion crosslinking network, thereby forming a double-network hydrogel structure.

[0010] In one or more embodiments, the mass ratio of the calcium lignosulfonate to the graphene oxide is 1:(0.24-0.4), and the mass ratio of the sodium alginate to the graphene oxide is 40:(1-3). Preferably, the mass ratio of the calcium lignosulfonate to the graphene oxide is 1:(0.3-0.4).

[0011] In one or more embodiments, the sheet size of the graphene oxide is 0.335-1.675 nm. The graphene oxide refers to various graphene oxides prepared by the Hummers method, the improved Hummers method, or commercially available.

[0012] In a second aspect, the present application provides a preparation method of the high-performance sodium alginate / graphene double network hydrogel, comprising the following steps:

[0013] mixing the calcium lignosulfonate aqueous solution, the graphene oxide aqueous solution and the sodium alginate aqueous solution to obtain a bio-ink through external field treatment;

[0014] obtaining a hydrogel preform through 3D printing of the bio-ink;

[0015] carrying out reduction treatment on the hydrogel preform to obtain the high-performance sodium alginate / graphene double network hydrogel.

[0016] In one or more embodiments, during the mixing of the calcium lignosulfonate aqueous solution, the graphene oxide aqueous solution and the sodium alginate aqueous solution, specifically, the calcium lignosulfonate aqueous solution is added to the graphene oxide aqueous solution, and then the sodium alginate aqueous solution is added after mixing.

[0017] Specifically, the calcium lignosulfonate aqueous solution is added to the graphene oxide aqueous solution, the sodium alginate aqueous solution is added after uniform mixing, the volume ratio of the three is adjusted, and ultrasonic dispersion is carried out to remove bubbles to obtain the bio-ink. The bio-ink is transferred to a 3D printing syringe, a hydrogel preform is obtained through 3D printing, and various printing parameters are adjusted. Then, the hydrogel preform is placed in an L-ascorbic acid (VC) solution for reduction treatment, and the high-performance sodium alginate / graphene double network hydrogel is obtained through reduction treatment.

[0018] In one or more embodiments, the external field treatment is one or more of vibration treatment, stirring treatment, centrifugal treatment, ultrasonic treatment and vacuum treatment.

[0019] In one or more embodiments, bubbles are removed through ultrasonic treatment after uniform mixing, the ultrasonic power is 300-500 W, and the time is 20-30 min.

[0020] In one or more embodiments, the concentration of the calcium lignosulfonate aqueous solution is 4-6 wt%.

[0021] Further, the purity of the calcium lignosulfonate is 90-95%.

[0022] Further, the molecular weight of the calcium lignosulfonate is 2000-3500.

[0023] Further, the sulfur content of the calcium lignosulfonate in the calcium lignosulfonate system is 2-5%.

[0024] In one or more embodiments, the concentration of the sodium alginate aqueous solution is 4.5-5.5 wt%.

[0025] In one or more embodiments, the concentration of the aqueous graphene oxide solution is 5-10 mg / mL.

[0026] In one or more embodiments, the volume ratio of the aqueous calcium lignosulfonate solution to the aqueous graphene oxide solution is 1:1.2-2, preferably 1:1.5-2.

[0027] The volume ratio of the aqueous sodium alginate solution to the aqueous graphene oxide solution is 1:0.1-0.3.

[0028] In one or more embodiments, the 3D printing is performed at a printing needle diameter of 0.41-0.42 mm and a pressure value of 16.9-17.2 psi.

[0029] Further, the printing substrate material is a high-density PET plate.

[0030] Further, the printing rate is 5-7 mm / s.

[0031] In one or more embodiments, the reduction treatment is performed by placing the hydrogel preform in an L-ascorbic acid (VC) solution.

[0032] Further, the purity of the L-ascorbic acid is 95-99%.

[0033] Further, the molar concentration of the L-ascorbic acid solution is 5.1-8.6%.

[0034] Further, the reduction temperature of the L-ascorbic acid is 60-70℃, and the time is 2-3 h.

[0035] In a third aspect, the application provides the use of the above-mentioned high-performance sodium alginate / graphene double-network hydrogel in biosensors, electromagnetic shielding, and conductive materials.

[0036] The application has the following advantages:

[0037] (1) In the preparation of the sodium alginate / graphene double-network hydrogel, the calcium lignosulfonate is used as both a dispersant and a crosslinking agent. Specifically, the calcium lignosulfonate is first added to the aqueous graphene oxide solution as a dispersant to avoid the agglomeration of the graphene oxide. The calcium lignosulfonate is dispersed on the graphene oxide and forms a layer of sheet network crosslinking through interfacial interaction. Then, the aqueous sodium alginate solution is added. At this time, the calcium lignosulfonate also functions as a crosslinking agent. The calcium ions and the carboxyl groups in the sodium alginate undergo ion exchange reactions to crosslink, thereby forming a sodium alginate / graphene composite hydrogel with a double-network structure. The sodium alginate / graphene double-network hydrogel has good physical strength and electrical conductivity.

[0038] (2) When the calcium lignosulfonate is used as a dispersant, the agglomeration problem of the graphene oxide is solved, the dispersion effect of the graphene is improved, and the mechanical property and the conductivity of the hydrogel are improved.

[0039] (3) When the calcium lignosulfonate is used as a crosslinking agent, the calcium lignosulfonate is crosslinked with the sodium alginate, so that the composite hydrogel with a double network structure is formed. Obviously, the special double network structure can also improve the mechanical property of the composite hydrogel. In addition, compared with the post-crosslinking method by using calcium chloride in the prior art, the calcium ions of the calcium lignosulfonate are fully crosslinked with the carboxyl groups in the sodium alginate by mixing the calcium lignosulfonate aqueous solution, the graphene oxide aqueous solution and the sodium alginate aqueous solution in a certain order, so that the residual free calcium ions are reduced as much as possible, the experimental steps are simplified, and the damage of the prepared composite hydrogel to cells in subsequent biological applications is avoided.

[0040] (4) In the mixing process of the calcium lignosulfonate aqueous solution, the graphene oxide aqueous solution and the sodium alginate aqueous solution, the performance of the hydrogel is also affected by the mixing order. When the calcium lignosulfonate aqueous solution is added to the graphene oxide aqueous solution, and then the sodium alginate aqueous solution is added after mixing, the hydrogel obtained by the mixing order has better performance.

[0041] (5) The experimental materials used in the present application are green and environmentally friendly, and the sources are wide. The method for preparing the sodium alginate / graphene oxide double network hydrogel is simple, easy to operate, and suitable for industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0042] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and the illustrative embodiments of the present application and their description serve the purpose of explaining the present application, and do not constitute an improper limitation of the present application.

[0043] Figure 1 A picture of the hydrogel ink based on alginate in Example 1 of the present application;

[0044] Figure 2 A structure diagram of a biosensor for bio-printing the hydrogel ink based on alginate in Example 1 of the present application;

[0045] Figure 3 A scanning electron microscope (SEM) image of the sodium alginate / graphene oxide double network hydrogel prepared in Example 1 of the present application; wherein (a) is a graphene oxide GO sheet structure, and (b) is a honeycomb structure of the sodium alginate / graphene oxide double network hydrogel. DETAILED DESCRIPTION

[0046] Unless otherwise specified, each raw material component in the following examples can be purchased through commercial channels, and the experimental instruments used are all laboratory conventional experimental instruments, and the performance testing method is a known testing method in the art.

[0047] In order to enable those skilled in the art to more clearly understand the technical solutions of the present application, the technical solutions of the present application will be described in detail below in combination with specific examples.

[0048] Example 1

[0049] The calcium lignosulfonate aqueous solution was added to the graphene oxide aqueous solution, and then the sodium alginate solution was added after mixing. The volume ratio of the three was adjusted, ultrasonic dispersion was performed to remove bubbles, and a bio-ink was obtained. The bio-ink was transferred to a 3D printing syringe, and a hydrogel preform was obtained by means of 3D printing. The printing parameters were adjusted. The hydrogel preform was placed in an L-ascorbic acid (VC) solution for reduction treatment, and a high-performance sodium alginate / graphene double-network hydrogel was obtained by reduction treatment.

[0050] The treatment conditions were as follows: the concentration of the calcium lignosulfonate aqueous solution was 4wt%; the purity of the calcium lignosulfonate was 90%; the molecular weight of the calcium lignosulfonate was 2000; the sulfur content of the calcium lignosulfonate was 2%; the concentration of the sodium alginate aqueous solution was 4.5wt%; the graphene oxide was prepared in the laboratory by means of an improved Hummers method; the sheet size of the graphene oxide was 1.675nm; the concentration of the graphene oxide aqueous solution was 10mg / mL; the volume ratio of the sodium alginate aqueous solution to the graphene oxide aqueous solution was 1:0.1; the volume ratio of the calcium lignosulfonate aqueous solution to the graphene oxide aqueous solution was 1:2. The ultrasonic power was 500W, and the time was 20min; the diameter of the printing needle was 0.42mm, and the pressure value was 17.2psi; the printing base material was a high-density PET plate; the printing rate was 7mm / s; the purity of the VC was 99%; the molar concentration of the VC solution was 8.6%; the reduction temperature of the VC was 70℃, and the time was 2h.

[0051] Example 2

[0052] Different from example 1, the sodium alginate was added to the graphene oxide aqueous solution, and then the calcium lignosulfonate aqueous solution was added after mixing.

[0053] Example 3

[0054] Different from example 1, the calcium lignosulfonate aqueous solution was added to the sodium alginate aqueous solution, and then the graphene oxide aqueous solution was added after mixing.

[0055] Comparative Example 1

[0056] Different from example 1, the 4wt% calcium lignosulfonate aqueous solution in example 1 was replaced by deionized water; wherein the volume ratio of the sodium alginate aqueous solution to the graphene oxide aqueous solution was 1:0.1; the volume ratio of the deionized water to the graphene oxide aqueous solution was 1:2.

[0057] Comparative example 2

[0058] Different from example 1, the calcium lignosulfonate aqueous solution in example 1 was replaced by an amine lignosulfonate aqueous solution.

[0059] wherein the concentration of the amine lignosulfonate aqueous solution was 4wt%; the purity of the amine lignosulfonate was 90%; the molecular weight of the amine lignosulfonate was 3500; the nitrogen content of the amine lignosulfonate was 4%; the volume ratio of the sodium alginate aqueous solution to the graphene oxide aqueous solution was 1:0.1; the volume ratio of the amine lignosulfonate aqueous solution to the graphene oxide aqueous solution was 1:2; the sodium alginate aqueous solution was added last.

[0060] Comparative example 3

[0061] Different from example 1, the sodium alginate aqueous solution and the graphene oxide aqueous solution were directly mixed, no lignosulfonate was added in the system, and the preform was placed in a calcium chloride aqueous solution for crosslinking after being obtained.

[0062] wherein the molar concentration of the CaCl2 solution was 28%; the crosslinking temperature was 25℃; the crosslinking time was 10min.

[0063] The tensile modulus of the hydrogels prepared in examples 1-3 and comparative examples 1-3 was tested by using a universal testing machine (CELTRON-STC), and the test conditions were as follows: temperature: 25±2℃, humidity: 50±5%, tensile speed: 5mm / min. The conductivity of the hydrogels prepared in examples 1-3 and comparative examples 1-3 was tested by using a digital source table (Keithley 2400), and the test conditions were as follows: temperature: 25±2℃, humidity: 50±5%, and the test results are shown in Table 1.

[0064] Table 1

[0065] Tensile modulus Mpa Electrical conductivity S / m Example 1 11±0.5 430±20 Example 2 8±0.5 300±20 Example 3 6±0.5 165±20 Comparative Example 1 0 132±20 Comparative Example 2 0 200±20 Comparative Example 3 10±0.5 129±20

[0066] Table 1 is the tensile modulus and conductivity of sodium alginate / graphene hydrogel prepared in Examples 1-3 and Comparative Examples 1-3. As can be seen from Table 1: the hydrogel added with calcium lignosulfonate system in a certain order, the mechanical properties and conductivity of Example 1 are obviously higher than those of Examples 2 and 3. Among them, Comparative Example 1 and Comparative Example 2 cannot form cross-linked structure by ion exchange reaction with carboxyl in sodium alginate molecules due to the absence of calcium atoms in the system, so the printed hydrogel preform cannot be shaped; at the same time, in Comparative Example 3, the use of CaCl2 solution for ion cross-linking will lead to the aggregation of graphene oxide in the system which cannot be dispersed, thereby affecting the conductivity of the hydrogel.

[0067] Example 4

[0068] Different from Example 1, the volume ratio of sodium alginate aqueous solution to graphene oxide aqueous solution is 1:0.1; the volume ratio of calcium lignosulfonate aqueous solution to graphene oxide aqueous solution is 1:1.2.

[0069] Example 5:

[0070] Different from Example 4, sodium alginate is added to the graphene oxide aqueous solution, and then the calcium lignosulfonate aqueous solution is added after mixing uniformly.

[0071] Example 6:

[0072] Different from Example 4, the calcium lignosulfonate aqueous solution is added to the sodium alginate aqueous solution, and then the graphene oxide aqueous solution is added after mixing uniformly, which is completely the same as Example 4.

[0073] Comparative Example 4:

[0074] Different from Example 4, deionized water is used to replace the calcium lignosulfonate aqueous solution in Example 4.

[0075] Comparative Example 5:

[0076] Different from Example 4, the calcium lignosulfonate aqueous solution is replaced by lignosulfonate amine aqueous solution. The concentration of the lignosulfonate amine aqueous solution is 4wt%; the purity of the lignosulfonate amine is 90%; the molecular weight of the lignosulfonate amine is 3500; the nitrogen content of the lignosulfonate amine is 4%; the volume ratio of sodium alginate aqueous solution to graphene oxide aqueous solution is 1:0.1; the volume ratio of lignosulfonate amine aqueous solution to graphene oxide aqueous solution is 1:1.2.

[0077] Comparative Example 6

[0078] Different from Example 4, the sodium alginate aqueous solution and the graphene oxide aqueous solution are directly mixed, no lignosulfonate is added in the system, and the preform is placed in a calcium chloride aqueous solution for cross-linking after being obtained.

[0079] The molar concentration of CaCl2 solution is 28%; the crosslinking temperature is 25°C; and the crosslinking time is 10 min.

[0080] The tensile modulus of the hydrogels prepared in Examples 4-6 and Comparative Examples 4-6 was tested using a universal testing machine (CELTRON-STC) under the following conditions: temperature: 25±2°C, humidity: 50±5%, and tensile speed: 5 mm / min. The conductivity of the hydrogels prepared in Examples 4-6 and Comparative Examples 4-6 was tested using a digital source meter (Keithley 2400) under the following conditions: temperature: 25±2°C, humidity: 50±5%, and the test results are shown in Table 2.

[0081] Table 2

[0082]

[0083]

[0084] Table 2 shows the tensile modulus and conductivity of the sodium alginate / graphene hydrogels prepared in Examples 4-6 and Comparative Examples 4-6. As shown in Table 2, when the content of the lignosulfonate system in the hydrogel is too high, the interaction between the dispersant and graphene is too strong, which makes the graphene too stable in the dispersion system, and makes the molecular structure of the dispersant complex, affecting its solubility and stability in the dispersion system, and thus adversely affecting the dispersion of graphene, resulting in a decrease in the mechanical properties and conductivity of the hydrogel.

[0085] Example 7

[0086] Unlike Example 1, the sulfur content of the calcium lignosulfonate is 5%.

[0087] Comparative Example 7

[0088] Unlike Example 7, the sodium alginate is added to the aqueous graphene oxide solution, and the calcium lignosulfonate aqueous solution is added after mixing.

[0089] Comparative Example 8

[0090] Unlike Example 7, the calcium lignosulfonate aqueous solution is added to the sodium alginate aqueous solution, and the aqueous graphene oxide solution is added after mixing.

[0091] The tensile modulus of the hydrogels prepared in Example 7 and Comparative Examples 7-8 was tested using a universal testing machine (CELTRON-STC) under the following conditions: temperature: 25±2℃, humidity: 50±5%, and tensile speed: 5mm / min. The conductivity of the hydrogels prepared in Example 7 and Comparative Examples 7-8 was tested using a digital source meter (Keithley 2400) under the following conditions: temperature: 25±2℃, humidity: 50±5%, and the test results are shown in Table 3.

[0092] Table 3

[0093] Tensile modulus Mpa Electrical conductivity S / m Example 7 7±0.5 285±20 Comparative Example 7 6±0.5 200±20 Comparative Example 8 4±0.5 100±20

[0094] Table 3 shows the tensile modulus and conductivity of the sodium alginate / graphene hydrogels prepared in Example 7 and Comparative Examples 7-8. As can be seen from Table 3, when the sulfur content of the calcium lignosulfonate in the hydrogel is too high, the interaction between the dispersant and the graphene is too strong, which makes the graphene too stable in the dispersion system, and the molecular structure of the dispersant becomes complex, affecting its solubility and stability in the dispersion system, and thus adversely affecting the dispersion of the graphene, resulting in a decrease in the mechanical properties and conductivity of the hydrogel.

[0095] The preferred embodiments of the present application have been described above with the purpose of not limiting the present application, and various modifications and changes can be made by those skilled in the art. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A high performance sodium alginate / graphene bi-network hydrogel, characterized in that, It comprises a sheet network crosslinked by interfacial interaction of calcium lignosulfonate and graphene oxide, and an ion crosslinked network formed by ion exchange of carboxyl of sodium alginate and calcium ion of calcium lignosulfonate; The preparation method of the high-performance sodium alginate / graphene double-network hydrogel comprises the following steps: Mixing calcium lignosulfonate aqueous solution, graphene oxide aqueous solution and sodium alginate aqueous solution to obtain bio-ink by external field treatment; The bio-ink is used to obtain a hydrogel preform by 3D printing; The hydrogel preform is subjected to reduction treatment to obtain the high-performance sodium alginate / graphene double-network hydrogel. During the mixing of the calcium lignosulfonate aqueous solution, the graphene oxide aqueous solution and the sodium alginate aqueous solution, the calcium lignosulfonate aqueous solution is added to the graphene oxide aqueous solution, and then the sodium alginate aqueous solution is added after mixing.

2. The high performance sodium alginate / graphene bi-network hydrogel according to claim 1, characterized in that, The mass ratio of the calcium lignosulfonate to the graphene oxide is 1:(0.24-0.4), and the mass ratio of the sodium alginate to the graphene oxide is 40:(1-3).

3. The high performance sodium alginate / graphene bi-network hydrogel according to claim 1, wherein, The sheet size of the graphene oxide is 0.335-1.675 nm.

4. The high performance sodium alginate / graphene bi-network hydrogel according to claim 2, wherein, The mass ratio of the calcium lignosulfonate to the graphene oxide is 1:(0.3-0.4).

5. The high performance sodium alginate / graphene bi-network hydrogel according to claim 1, wherein, The external field treatment is one or more of vibration treatment, stirring treatment, centrifugal treatment, ultrasonic treatment and vacuum treatment.

6. The high performance sodium alginate / graphene bi-network hydrogel according to claim 5, wherein, The ultrasonic power is 300-500 W, and the time is 20-30 min.

7. The high performance sodium alginate / graphene bi-network hydrogel according to claim 1, wherein, The concentration of the calcium lignosulfonate aqueous solution is 4-6 wt%.

8. The high performance sodium alginate / graphene bi-network hydrogel according to claim 1, wherein, The purity of the calcium lignosulfonate is 90-95%.

9. The high performance sodium alginate / graphene bi-network hydrogel according to claim 1, wherein, The molecular weight of the calcium lignosulfonate is 2000-3500.

10. The high performance sodium alginate / graphene bi-network hydrogel according to claim 1, wherein, The concentration of the sodium alginate aqueous solution is 4.5-5.5 wt%.

11. The high performance sodium alginate / graphene bi-network hydrogel according to claim 1, wherein, The concentration of the graphene oxide aqueous solution is 5-10 mg / mL.

12. The high performance sodium alginate / graphene bi-network hydrogel according to claim 1, wherein, The volume ratio of the calcium lignosulfonate aqueous solution to the graphene oxide aqueous solution is 1:1.2-2. The volume ratio of the sodium alginate aqueous solution to the graphene oxide aqueous solution is 1:0.1-0.

3.

13. The high performance sodium alginate / graphene bi-network hydrogel according to claim 12, wherein, The volume ratio of the calcium lignosulfonate aqueous solution to the graphene oxide aqueous solution is 1:1.5-2.

14. The high performance sodium alginate / graphene bi-network hydrogel according to claim 1, wherein, The 3D printing has a printing needle diameter of 0.41-0.42 mm and a pressure value of 16.9-17.2 psi.

15. The high performance sodium alginate / graphene bi-network hydrogel according to claim 14, wherein, The printing base material is a high-density PET plate.

16. The high performance sodium alginate / graphene bi-network hydrogel according to claim 14, wherein, The printing rate is 5-7 mm / s.

17. The high performance sodium alginate / graphene bi-network hydrogel according to claim 1, wherein, The reduction treatment is that the hydrogel preform is placed in an L-ascorbic acid solution for reduction treatment.

18. The high performance sodium alginate / graphene bi-network hydrogel according to claim 17, wherein, The purity of the L-ascorbic acid is 95-99%.

19. The high performance sodium alginate / graphene bi-network hydrogel according to claim 17, wherein, The molar concentration of the L-ascorbic acid solution is 5.1-8.6%.

20. The high performance sodium alginate / graphene bi-network hydrogel according to claim 17, wherein, The reduction temperature of the L-ascorbic acid is 60-70℃, and the time is 2-3 h.

21. The high-performance sodium alginate / graphene double-network hydrogel according to any one of claims 1-20 is applied in biosensors, electromagnetic shielding and conductive materials.

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