Preparation of green and environment-friendly high-viscosity conductive material

Abstract

The invention discloses preparation of a green and environment-friendly high-viscosity conductive material, sodium alginate and polyvinyl alcohol composite hydrogel is used as a matrix, alkali treatment is utilized to preliminarily enhance the mechanical property of the hydrogel, a green eutectic solvent is utilized to replace water, and heating treatment is performed to obtain ionic gel, the preparation steps are simple, and the used raw materials are all green and environment-friendly. By introducing magnesium and boron components, the ionic gel is endowed with excellent adhesion performance and thermal stability, and can maintain good adhesion performance at a relatively high temperature. The green environment-friendly Mg / B-SA / PVA ionic gel prepared by the invention has excellent mechanical properties, ionic conductivity and ultrahigh viscosity, and has important application potential in the high-tech fields of tissue adhesives, intelligent wearable equipment, energy storage and the like.

Description

Technical Field

[0001] The present invention belongs to the field of material technology, and in particular relates to the preparation of a class of green, environmentally friendly, high-viscosity conductive materials. Background Art

[0002] Hydrogel is a semisolid substance with a three-dimensional porous structure, among which adhesive hydrogels are widely used in electronic skin, wearable devices and tissue adhesives. The Chinese patent with publication number CN119661783A reported a zwitterionic composite hydrogel adhesive and its preparation method. A one-pot copolymerization method was adopted, and MBAA and borax were used as cross-linking agents to prepare a zwitterionic polyelectrolyte hydrogel containing SBMA, PVA, THMA and AMPS. The maximum adhesion strength was 33kPa and the tensile strength was 0.13MPa. The Chinese patent with publication number CN119060366A reported a polyphenol-based double network adhesive hydrogel and its preparation method and application. By constructing a poly(acrylamide-co-acrylic acid)-sodium alginate double network hydrogel and cross-linking the tannic acid and Mg on the poly(acrylamide-co-acrylic acid)-sodium alginate double network hydrogel through hydrogen bonds. 2+ The maximum adhesion strength of the obtained hydrogel is 123.47 kPa, but the hydrogel requires a variety of organic solvents and initiators for processing, the preparation process is complicated and has an impact on the environment.

[0003] Currently, commonly used adhesives are primarily water-based and solvent-based. Organic solvent-based adhesives can pollute the environment during production and application, making the development of environmentally friendly adhesives of great research significance. Eutectic solvents, as a new, green alternative to ionic liquids, have a wide range of applications. Chinese patent publication number CN119161596A reports a self-adhesive, wide-temperature strain sensing, and highly sensitive conductive eutectic gel, as well as its preparation method and application. This gel exhibits excellent sensitivity and strain sensing performance, with an ionic conductivity exceeding 0.5 S / m after one month at room temperature. However, its adhesion strength is relatively low, at only 6.81 kPa. Hu et al. reported a class of multifunctional covalent polymer eutectic gels for use in sealable adhesives (Chemical Engineering Journal, 2025, 509:161-269). The adhesion strengths of DMAA-DES (1:9, 2:8, and 3:7) eutectic gels were 24.3, 102, and 158 kPa, respectively. The maximum adhesion strength of the eutectic gels gradually increased with decreasing DES ratios. The high adhesion of eutectic gels is primarily due to the non-covalent interactions between their specific structure and various substrates. Chinese Patent Publication No. CN116410398A reports a high-strength, high-viscosity hydrophobic eutectic gel and its preparation method. The resulting eutectic gel exhibits high viscosity and transparency, and its electrical resistance changes with movement, enabling motion monitoring. However, the preparation process requires a fluorinated acrylate monomer, isobornyl acrylate, a crosslinker, and an initiator, resulting in a complex process and toxic raw materials.

[0004] In the above-mentioned prior art, the preparation process of existing adhesives is relatively cumbersome and the performance does not meet the requirements. Therefore, there is an urgent need to prepare green and environmentally friendly high-viscosity conductive materials to meet the needs of high-tech industries such as smart wearables, smart devices and energy storage. Summary of the Invention

[0005] The main purpose of the present invention is to provide a preparation method for a type of green, environmentally friendly, high-viscosity conductive material. The preparation method is simple to operate and the raw materials are green and environmentally friendly. The adhesive prepared by the present invention has high adhesion strength, high mechanical properties and excellent conductive properties, and has a wide range of applications.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] The present invention discloses an adhesive, the raw materials of which include sodium alginate, polyvinyl alcohol and polyol, etc., and the preparation of a type of green, environmentally friendly and highly viscous conductive material includes the following steps:

[0008] (1) uniformly mixing a sodium alginate (SA) aqueous solution and a polyvinyl alcohol (PVA) aqueous solution to obtain a SA / PVA mixed solution; subjecting the SA / PVA mixed solution to a freeze-thaw process to obtain a SA / PVA hydrogel;

[0009] (2) magnesium salt, boric acid, ethylene glycol and glycerol are mixed in a certain proportion to obtain DES and Mg / B-DES solvents;

[0010] (3) soaking the SA / PVA hydrogel obtained in step (1) in a strong alkaline solution of a certain concentration;

[0011] (4) The SA / PVA obtained in step (3) NaOH The hydrogel is immersed in the DES and Mg / B-DES solvent obtained in step (2);

[0012] (5) The composite gel obtained in step (4) is subjected to a heat treatment to obtain a high-viscosity conductive material Mg / B-SA / PVA gel.

[0013] Preferably, in step (1), the mass percentage of sodium alginate is 1-3 wt%, and the mass percentage of PVA is 5-10 wt%.

[0014] Preferably, the M / G ratio of sodium alginate in step (1) is 1:1, 1:2 and 2:1.

[0015] Preferably, the magnesium salt in step (2) is a soluble magnesium salt such as magnesium chloride, magnesium sulfate, magnesium nitrate and magnesium acetate.

[0016] Preferably, the molar mass ratio of the DES in step (2) is ethylene glycol:glycerol=3:2; the ratio of Mg / B-DES is magnesium salt:boric acid:ethylene glycol:glycerol=1:(0-1):3:2.

[0017] Preferably, the strong base in step (3) is sodium hydroxide or potassium hydroxide, and the concentration of the strong base is 1 to 10 mol / L.

[0018] Preferably, in step (4), the soaking time in the DES solvent is 0 to 30 minutes, and the soaking time in the Mg / B-DES solvent is 12 to 24 hours.

[0019] Preferably, the heating temperature in step (5) is 30-200°C.

[0020] Preferably, the heat treatment time in step (5) is 0.5 to 48 hours.

[0021] The present invention provides a preparation method for a type of green and environmentally friendly high-viscosity conductive material. The advantages are: the sodium alginate, polyvinyl alcohol and polyol used in the adhesive are all green and environmentally friendly raw materials, the preparation method is simple, the first step of alkali treatment can increase the mechanical properties of freeze-thawed SA / PVA gel, and then an ion gel is generated through water and DES solvent exchange. The introduction of magnesium and boron components gives the SA / PVA gel adhesion. Changing the heat treatment temperature can obtain Mg / B-SA / PVA gels with different adhesion strengths, and the maximum adhesion strength is 548.25 kPa. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Graph showing the adhesion strength of Examples 1 to 9 and Comparative Examples 1 to 4.

[0023] Figure 2 These are optical photographs of Examples 1 to 9.

[0024] Figure 3 Figure 3 is the adhesion result of Example 3 on different substrates.

[0025] Figure 4 These are optical photographs of the ion gels of Comparative Examples 5 to 16.

[0026] Figure 5 This is the uniaxial tensile test result of Example 3.

[0027] Figure 6 The AC impedance and ionic conductivity diagrams of Examples 1 to 4 are shown.

[0028] Figure 7 This is a conductive path diagram of Example 3. DETAILED DESCRIPTION

[0029] Example 1

[0030] The preparation of a green and environmentally friendly high-viscosity conductive material includes the following steps:

[0031] (1) Sodium alginate was dissolved in water at 80° C. to prepare a 1 wt% sodium alginate aqueous solution, which was then allowed to cool and degassed at room temperature for later use;

[0032] (2) dissolving polyvinyl alcohol in water at 95° C. with stirring to prepare a 5 wt % polyvinyl alcohol aqueous solution, and allowing to cool and degas at room temperature for later use;

[0033] (3) Prepare SA / PVA mixed solution at a volume ratio of SA:PVA = 1:1, stir evenly at room temperature and set aside;

[0034] (4) The obtained SA / PVA mixed solution was frozen at -18°C for 24 hours and then thawed at room temperature to obtain SA / PVA hydrogel. (5) Ethylene glycol and glycerol were heated and stirred at 100°C for 6 hours in a molar mass ratio of 3:2 to obtain a clear and transparent DES solvent.

[0035] (6) MgCl2·6H2O, ethylene glycol, and glycerol were heated and stirred at 100°C in a molar mass ratio of 1:3:2 for 4 h to obtain a clear and transparent Mg-DES solvent. A 0.4 M boric acid solution was then prepared using Mg-DES as the solvent and heated and stirred at 100°C for 2 h to obtain a clear Mg / B-DES solvent.

[0036] (7) The SA / PVA hydrogel obtained in step (4) was placed in a 1M NaOH solution for 24 h to obtain SA / PVA NaOH (8) The SA / PVA obtained in step (7) NaOH The hydrogel was immersed in the DES solvent obtained in step (5) for 5 minutes.

[0037] (9) The gel obtained in step (8) was placed in Mg / B-DES solvent for solvent exchange for 24 h.

[0038] (10) The gel obtained in step (9) was placed at 50°C for 24 hours to obtain Mg / B-SA / PVA 50 gel.

[0039] Examples 2 to 6

[0040] The preparation of a green and environmentally friendly high-viscosity conductive material includes the following steps:

[0041] The difference between Examples 2 to 6 and Example 1 is that the treatment temperatures in step (10) are 60, 70, 80, 90 and 100° C., and the rest are the same as Example 1.

[0042] Example 7

[0043] The preparation of a green and environmentally friendly high-viscosity conductive material includes the following steps:

[0044] The difference between Example 7 and Example 1 is that the treatment temperature in step (10) is 120° C. and the treatment time is 8 h. The rest is the same as Example 1.

[0045] Examples 8-9

[0046] The preparation of a green and environmentally friendly high-viscosity conductive material includes the following steps:

[0047] The difference between Examples 8 and 9 and Example 1 is that the treatment temperature in step (10) is 140 and 160° C., and the treatment time is 2 h. The rest is the same as Example 1.

[0048] Comparative Example 1

[0049] (1) Sodium alginate was dissolved in water at 80° C. to prepare a 1 wt% sodium alginate aqueous solution, which was then allowed to cool and degassed at room temperature for later use;

[0050] (2) dissolving polyvinyl alcohol in water at 95° C. with stirring to prepare a 5 wt % polyvinyl alcohol aqueous solution, and allowing to cool and degas at room temperature for later use;

[0051] (3) Prepare SA / PVA mixed solution at a volume ratio of SA:PVA = 1:1, stir evenly at room temperature and set aside;

[0052] (4) The obtained SA / PVA mixed solution was frozen at -18°C for 24 hours and then thawed at room temperature to obtain SA / PVA hydrogel. (5) Ethylene glycol and glycerol were heated and stirred at 100°C for 6 hours in a molar mass ratio of 3:2 to obtain a clear and transparent DES solvent.

[0053] (6) MgCl2·6H2O, ethylene glycol, and glycerol were heated and stirred at 100°C for 6 h in a molar mass ratio of 1:3:2 to obtain a clear and transparent Mg-DES solvent.

[0054] (7) The SA / PVA hydrogel obtained in step (4) was placed in a 1M NaOH solution for 24 h to obtain SA / PVA NaOH (8) The SA / PVA obtained in step (7) NaOH The hydrogel was immersed in the DES solvent obtained in step (5) for 5 minutes.

[0055] (9) The gel obtained in step (8) was placed in Mg-DES solvent for solvent exchange for 24 h.

[0056] (10) The gel obtained in step (9) was placed at 50°C for 24 hours to obtain Mg-SA / PVA 50 gel.

[0057] Comparative Examples 2 to 4

[0058] The preparation of a green and environmentally friendly high-viscosity conductive material includes the following steps:

[0059] The difference between Comparative Examples 2 to 4 and Comparative Example 1 is that the treatment temperature in step (10) is 60, 70 and 80° C., and the rest is the same as Comparative Example 1.

[0060] Comparative Example 5

[0061] (1) Sodium alginate was dissolved in water at 80° C. to prepare a 1 wt% sodium alginate aqueous solution, which was then allowed to cool and degassed at room temperature for later use;

[0062] (2) dissolving polyvinyl alcohol in water at 95° C. with stirring to prepare a 5 wt % polyvinyl alcohol aqueous solution, and allowing to cool and degas at room temperature for later use;

[0063] (3) Prepare SA / PVA mixed solution at a volume ratio of SA:PVA = 1:1, stir evenly at room temperature and set aside;

[0064] (4) The obtained SA / PVA mixed solution was frozen at -18°C for 24 hours and then thawed at room temperature to obtain SA / PVA hydrogel. (5) Ethylene glycol and glycerol were heated and stirred at 100°C for 6 hours in a molar mass ratio of 3:2 to obtain a clear and transparent DES solvent.

[0065] (6) The SA / PVA hydrogel obtained in step (4) was placed in a 1M NaOH solution for 24 h to obtain SA / PVA NaOH (7) The SA / PVA obtained in step (6) NaOH The hydrogel was immersed in the DES solvent obtained in step (5) for solvent exchange for 24 h.

[0066] (8) The gel obtained in step (7) was placed at 50°C for 24 hours to obtain DES-SA / PVA 50 gel.

[0067] Comparative Examples 6 to 8

[0068] The difference between Comparative Examples 6 to 8 and Comparative Example 5 is that the processing temperatures in step (8) are 60, 70 and 80° C., respectively, and the rest are the same as Comparative Example 5.

[0069] Comparative Example 9

[0070] (1) Sodium alginate was dissolved in water at 80° C. to prepare a 1 wt% sodium alginate aqueous solution, which was then allowed to cool and degassed at room temperature for later use;

[0071] (2) dissolving polyvinyl alcohol in water at 95° C. with stirring to prepare a 5 wt % polyvinyl alcohol aqueous solution, and allowing to cool and degas at room temperature for later use;

[0072] (3) Prepare SA / PVA mixed solution at a volume ratio of SA:PVA = 1:1, stir evenly at room temperature and set aside;

[0073] (4) The obtained SA / PVA mixed solution was frozen at -18°C for 24 hours and then thawed at room temperature to obtain SA / PVA hydrogel. (5) Ethylene glycol and glycerol were heated and stirred at 100°C for 6 hours in a molar mass ratio of 3:2 to obtain a clear and transparent DES solvent.

[0074] (6) CaCl2, ethylene glycol, and glycerol were heated and stirred at 100 °C for 6 h in a molar mass ratio of 1:3:2 to obtain a clear and transparent Ca-DES solvent.

[0075] (7) The SA / PVA hydrogel obtained in step (4) was placed in a 1M NaOH solution for 24 h to obtain SA / PVA NaOH (8) The SA / PVA obtained in step (7) NaOH The hydrogel was immersed in the DES solvent obtained in step (5) for 5 minutes.

[0076] (9) The gel obtained in step (8) was placed in Ca-DES solvent for solvent exchange for 24 h.

[0077] (10) The gel obtained in step (9) was placed at 50°C for 24 hours to obtain Ca-SA / PVA 50 gel.

[0078] Comparative Examples 10-12

[0079] The difference between Comparative Examples 10 to 12 and Comparative Example 9 is that the processing temperatures in step (10) are 60, 70 and 80° C., respectively, and the rest are the same as Comparative Example 9.

[0080] Comparative Example 13

[0081] (1) dissolving polyvinyl alcohol in water at 95° C. with stirring to prepare a 5 wt % polyvinyl alcohol aqueous solution, and allowing to cool and degas at room temperature for later use;

[0082] (2) The obtained PVA solution was frozen at -18°C for 24 hours and then thawed at room temperature to obtain PVA hydrogel.

[0083] (3) Ethylene glycol and glycerol were heated and stirred at 100 °C for 6 h to obtain a clear and transparent DES solvent.

[0084] (4) MgCl2·6H2O, ethylene glycol, and glycerol were heated and stirred at 100°C in a molar mass ratio of 1:3:2 for 4 h to obtain a clear and transparent Mg-DES solvent. A 0.4 M boric acid solution was then prepared using Mg-DES as the solvent and heated and stirred at 100°C for 2 h to obtain a clear Mg / B-DES solvent.

[0085] (5) The PVA hydrogel obtained in step (2) was placed in a 1M NaOH solution for 24 hours to obtain PVA NaOH hydrogel.

[0086] (6) PVA obtained in step (5) NaOH The hydrogel was immersed in the DES solvent obtained in step (3) for 5 min.

[0087] (7) The gel obtained in step (6) was placed in Mg / B-DES solvent for solvent exchange for 24 h.

[0088] (8) The gel obtained in step (7) was placed at 50°C for 24 hours to obtain Mg / B-PVA 50 gel.

[0089] Comparative Examples 14 to 16

[0090] The difference between Comparative Examples 14 to 16 and Comparative Example 13 is that the processing temperatures in step (8) are 60, 70 and 80° C., respectively, and the rest are the same as Comparative Example 13.

[0091] Figure 1 The adhesion strength diagram of Examples 1 to 9 and Comparative Examples 1 to 4 shows that the ion gel with added B has greater adhesion strength. As the treatment temperature increases, the adhesion strength increases significantly. Mg / B-SA / PVA 100 The adhesion strength is the highest, reaching 548.25kPa. As the temperature continues to rise, the adhesion strength will gradually decrease, but it will still maintain a high adhesion strength.

[0092] Figure 2 These are optical photographs of Examples 1 to 9. As can be seen from the figures, as the treatment temperature increases, the color of the ion gel gradually turns yellow. Under high temperature conditions, the color will turn yellow after a short treatment time.

[0093] Figure 3 The adhesion results of Example 3 on different substrates are shown in the figure. As can be seen from the figure, the ion gel has excellent adhesion to materials such as paper, metal, rubber, fiber, wood and glass, and the ion gel can also fit well on the skin.

[0094] Figure 4 The optical photographs of the ion gels of comparative examples 5 to 16 show the ion gels without cations and with different cations (Ca 2+ ) on the performance of ion gel. As can be seen from the figure, DES gel without cations shows different degrees of yellow at different treatment temperatures. 2+The ion gel is white, and the transparency of the gel increases with the increase of treatment temperature. The surface of the Mg / B-PVA ion gel without SA is covered with white powder. This is because Mg 2+ Cannot cross-link with PVA, resulting in Mg 2+ It cannot be fixed and can only react with the alkali inside the gel to form magnesium hydroxide. This phenomenon is not found in Mg / B-SA / PVA gel because Mg 2+ Can cross-link with SA. Therefore, SA is indispensable in this system. The above gels do not contain stickiness, which indicates that Mg 2+ And the necessity of SA for the adhesion properties of the ion gel system.

[0095] Figure 5 The uniaxial tensile test results of Example 3 are shown in the figure. 70 The tensile strength is 0.61MPa and the fracture strain is 513%, which shows excellent mechanical properties.

[0096] Figure 6 The AC impedance diagrams and ionic conductivities of Examples 1 to 4 are shown. As can be seen from the figures, the Mg / B-SA / PVA ion gel has excellent ion diffusion rate and high ionic conductivity.

[0097] Figure 7 This is a diagram of the conductive path of Example 3. As can be seen from the figure, under a 3V external power supply, the ion gel can serve as a part of the conductive path and can light up the diode well.

[0098] The embodiments described above provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements and equivalent substitutions made within the scope of the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. Preparation of a green and environmentally friendly high-viscosity conductive material, characterized in that: The following steps are involved: (1) uniformly mixing a sodium alginate (SA) aqueous solution and a polyvinyl alcohol (PVA) aqueous solution to obtain a SA / PVA mixed solution; subjecting the SA / PVA mixed solution to a freeze-thaw process to obtain a SA / PVA hydrogel; (2) magnesium salt, boric acid, ethylene glycol and glycerol are mixed in a certain proportion to obtain DES and Mg / B-DES solvents; (3) soaking the SA / PVA hydrogel obtained in step (1) in a strong alkaline solution of a certain concentration; (4) The SA / PVA obtained in step (3) NaOH The hydrogel is immersed in the DES and Mg / B-DES solvent obtained in step (2); (5) The composite gel obtained in step (4) is subjected to a heat treatment to obtain a high-viscosity conductive material Mg / B-SA / PVA.

2. The preparation method of a green, environmentally friendly, high-viscosity conductive material according to claim 1, characterized in that: In step (1), the mass percentage of sodium alginate is 1-3 wt%, and the mass percentage of PVA is 5-10 wt%.

3. The preparation of a green, environmentally friendly, high-viscosity conductive material according to claim 1, characterized in that: The M / G ratios of sodium alginate in step (1) are 1:1, 1:2 and 2:

1.

4. The preparation of a green, environmentally friendly, high-viscosity conductive material according to claim 1, characterized in that: The magnesium salt in step (2) is a soluble magnesium salt such as magnesium chloride, magnesium sulfate, magnesium nitrate and magnesium acetate.

5. The preparation of a green, environmentally friendly, high-viscosity conductive material according to claim 1, characterized in that: The molar mass ratio of the DES described in step (2) is ethylene glycol:glycerol = 3:2; the ratio of Mg / B-DES is magnesium salt:boric acid:ethylene glycol:glycerol = 1:(0-1):3:

2.

6. The preparation of a green, environmentally friendly, high-viscosity conductive material according to claim 1, characterized in that: The strong base in step (3) is sodium hydroxide or potassium hydroxide, and the concentration of the strong base is 1 to 10 mol / L.

7. The preparation of a green, environmentally friendly, high-viscosity conductive material according to claim 1, characterized in that: In step (4), the soaking time in the DES solvent is 0 to 30 minutes, and the soaking time in the Mg / B-DES solvent is 12 to 24 hours.

8. The preparation of a green, environmentally friendly, high-viscosity conductive material according to claim 1, characterized in that: The heating temperature in step (5) is 30 to 200°C.

9. The preparation of a green, environmentally friendly, high-viscosity conductive material according to claim 1, characterized in that: The heat treatment time in step (4) is 0.5 to 48 hours.

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