All-weather anti-fatigue conductive hydrogel and preparation method and application thereof

Abstract

The application provides an all-weather anti-fatigue conductive hydrogel as well as a preparation method and application thereof, and the preparation method comprises the following steps: first, constructing a highly oriented nanofiber structure through an ice template method, and then immersing the nanofiber structure in a mixed solution of a salt with a Hofmeister effect and an anti-freezing agent for a certain time, so that the all-weather anti-fatigue conductive hydrogel is obtained. The all-weather anti-fatigue conductive hydrogel has good toughness and anti-fatigue property, has good conductive property while enhancing the mechanical property, solves the problems of poor mechanical property of a traditional conductive hydrogel, fatigue fracture under long-term cyclic load, and evaporation or icing of water molecules to cause a decrease in conductivity, maintains the performance stability of the hydrogel, is suitable for long-time use, and has a simple preparation method, so that the application range of the hydrogel in the fields of sensors, friction nanogenerators, artificial ligaments and the like is widened, a key material is provided for the development of a flexible electronic device, and the hydrogel has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of flexible electronic device technology, specifically relating to an all-weather fatigue-resistant conductive hydrogel, its preparation method, and its application. Background Technology

[0002] Hydrogels offer a highly tunable modulus range, encompassing the modulus range of various human soft tissues (skin, brain, muscle, and cartilage, etc.), and have gained widespread attention in fields such as human motion monitoring, healthcare, and soft robotics. However, the poor mechanical properties of traditional hydrogels severely limit the application of hydrogel-based electronic devices in applications requiring long-term resistance to cyclic loads.

[0003] Currently, common and effective methods to improve the mechanical strength of gels include introducing energy dissipation mechanisms, such as constructing unique dual-network structures. However, due to the inhomogeneity between networks, increasing stiffness often leads to decreased toughness. Additionally, embedding various nanofillers such as carbon nanotubes, graphene, and metal nanoparticles into elastic polymers can enhance mechanical properties while improving electrical conductivity. However, these methods result in high Young's modulus, making them highly susceptible to irreversible damage and leading to unstable applications.

[0004] Through rational structural design, such as the ice-templating method or mechanical training, the mechanical properties of the oriented structure can be improved. For example, CN115746490A designed an anisotropic, highly conductive hydrogel using the ice-templating method, which can be applied to the design and fabrication of flexible sensors; CN115010959A uses citrate as a crosslinking agent to promote the lateral aggregation of polymer molecular chains and improve mechanical properties. The presence of amino-modified MXene and a large number of free ions gives the hydrogel good conductivity and sensing properties. However, the above gels exhibit low performance stability under repeated cyclic loading and extreme environments. Therefore, there is an urgent need in this field for a novel fatigue-resistant conductive hydrogel that can improve mechanical properties and environmental tolerance while meeting conductivity requirements, thereby expanding its performance stability and application range, and providing a key material for the development of flexible electronics. Summary of the Invention

[0005] The purpose of this invention is to provide an all-weather fatigue-resistant conductive hydrogel, its preparation method, and its application.

[0006] This invention provides an all-weather fatigue-resistant conductive hydrogel, which is prepared by mixing a gel matrix solution and conductive filler as raw materials through directional freezing, and then immersing the mixture in a mixed solution of a salt exhibiting the Hofmeister effect and an antifreeze agent. The mass concentration of the gel matrix solution in the raw materials is 2.5wt%-40wt%, and the concentration of the conductive filler is 0.2mg / mL-6.0mg / mL; the molar concentration of the salt exhibiting the Hofmeister effect is 0.005M-20M.

[0007] The gel matrix solution is selected from any one or more of the following: chitosan solution, quaternary ammonium chitosan solution, carboxymethyl chitosan solution, hyaluronic acid solution, alginate solution, sodium alginate solution, gelatin solution, cellulose solution, sodium carboxymethyl cellulose solution, collagen solution, polyoxyethylene solution, polyvinyl alcohol solution, polyethylene glycol solution, polyacrylamide solution, polyacrylic acid solution, sodium polyacrylate solution, polymethyl acrylate solution, polymethacrylic acid solution, polyethyl methacrylate solution, hydroxyethyl methacrylate solution, polyacrylamide-acrylic acid copolymer solution, agar solution, collagen solution, and cyclodextrin solution.

[0008] The conductive filler is selected from gold nanowires, silver nanowires, copper nanowires, carbon nanotubes, carbon fibers, conductive carbon black, graphite, and MXene (Nb4C3T). x Ti3CNT x Ti2CT x Ti3C2T x V2T x Mo2Ti2C3T x ), graphene, polyaniline, polypyrrole, polythiophene, polyacetylene, copper oxide, aluminum oxide, zinc oxide, iron tetroxide, ruthenium dioxide, titanium monoxide, or any two or more of these;

[0009] The salt exhibiting the Hofmeister effect is any one or more of the following: magnesium sulfate, magnesium chloride, sodium carbonate, sodium bicarbonate, sodium chloride, sodium dihydrogen phosphate, sodium phosphate, sodium acetate, sodium nitrate, sodium citrate, sodium bisulfate, sodium sulfate, sodium thiosulfate, sodium iodide, cesium carbonate, cesium sulfate, cesium nitrate, lithium sulfate, lithium chloride, potassium chloride, potassium carbonate, potassium sulfate, ammonium sulfate, and calcium chloride.

[0010] The antifreeze agent is selected from any one or more of methanol, ethanol, ethylene glycol, propylene glycol, acetone glycerol, glycerol, isopropanol, butanediol, diethylene glycol, sorbitol, ethylene glycol butyl ether, ethylene glycol tert-butyl ether, and propylene glycol butyl ether.

[0011] The gel matrix solution is any one or more of the following: chitosan solution, quaternary ammonium chitosan solution, sodium alginate solution, gelatin solution, cellulose solution, polyoxyethylene solution, polyvinyl alcohol solution, polyethylene glycol solution, polyacrylamide solution, sodium polyacrylate solution, polymethacrylic acid solution, and polyacrylamide-acrylic acid copolymer solution.

[0012] The conductive filler is silver nanowire, carbon nanotube, carbon black, graphite, or MXene (Ti3CNT). x Ti2CT x Ti3C2T x V2T x), graphene, polyaniline and polypyrrole, any one or more of the following;

[0013] The salt exhibiting the Hofmeister effect is any one or more of the following: magnesium sulfate, magnesium chloride, sodium carbonate, sodium bicarbonate, sodium chloride, sodium dihydrogen phosphate, sodium phosphate, sodium citrate, sodium bisulfate, sodium sulfate, sodium thiosulfate, cesium carbonate, lithium chloride, potassium chloride, potassium carbonate, potassium sulfate, and ammonium sulfate.

[0014] The antifreeze agent is any one or more of ethanol, ethylene glycol, propylene glycol, acetone glycerol, glycerol, sorbitol, diethylene glycol, and propylene glycol butyl ether.

[0015] The mass concentration of the gel matrix is ​​5wt%-30wt%; the concentration of the conductive filler is 0.5mg / mL-3mg / mL; and the molar concentration of the salt exhibiting the Hofmeister effect is 0.05M-10M.

[0016] More preferably,

[0017] The mass concentration of the gel matrix is ​​5wt%-20wt%; the molar concentration of the salt exhibiting the Hofmeister effect is 0.05M-5M.

[0018] More preferably,

[0019] The gel matrix is ​​cellulose; the conductive filler is silver nanowires at 2 mg / mL; the salt exhibiting the Hofmeister effect is 3M NaCl; and the antifreeze agent is ethylene glycol.

[0020] The gel matrix is ​​cellulose; the conductive filler is titanium monoxide 2 mg / mL; the salt exhibiting the Hofmeister effect is 4 M Na2CO3; and the antifreeze agent is ethylene glycol.

[0021] The gel matrix is ​​chitosan; the conductive filler is titanium monoxide 2 mg / mL; the salt with the Hofmeister effect is 3M Na2S2O3; and the antifreeze agent is diethylene glycol.

[0022] The gel matrix is ​​gelatin; the conductive filler is graphene 1 mg / mL; the salt exhibiting the Hofmeister effect is 3M(NH4)2SO4; and the antifreeze agent is glycerol.

[0023] The gel matrix is ​​polyethylene oxide; the conductive filler is Ti2CT. x 1 mg / mL, wherein the salt exhibiting the Hofmeister effect is 2M Na2SO4, and the antifreeze is ethylene glycol butyl ether.

[0024] This invention also provides a method for preparing an all-weather fatigue-resistant conductive hydrogel, characterized by comprising the following steps:

[0025] a. After the gel matrix solution and conductive filler are mixed evenly, the mixture is injected into a PTFE mold and then directionally frozen under liquid nitrogen to obtain the mixture;

[0026] b. Immerse the mixture from step a in a mixed solution of salt and antifreeze with the Hofmeister effect, and soak it to obtain an all-weather fatigue-resistant conductive hydrogel.

[0027] The antifreeze mixture is composed of the following components by weight percentage: 10wt%-80wt% antifreeze and 90wt%-20wt% deionized water solvent; preferably, 30wt%-70wt% antifreeze and 70wt%-30wt% deionized water solvent; more preferably, 30wt%-65wt% antifreeze and 70wt%-35wt% deionized water solvent.

[0028] The soaking temperature is -20℃ to 25℃, and the soaking time is 2h to 168h; preferably, the soaking temperature is -20℃ to 20℃, and the soaking time is 12h to 144h; more preferably, the soaking temperature is -20℃ to 10℃, and the soaking time is 24h to 96h.

[0029] The mixed solution of salt and antifreeze with the Hofmeister effect is pre-cooled at -20℃ to 10℃ for 0.5h to 5h.

[0030] The present invention also provides applications of the hydrogel in the fields of sensors, triboelectric nanogenerators, and artificial ligaments.

[0031] This invention provides an all-weather fatigue-resistant conductive hydrogel and its preparation method. By utilizing an ice-templating method combined with a salting-out synergistic solvent replacement strategy, an all-weather fatigue-resistant conductive hydrogel was successfully prepared, exhibiting excellent mechanical properties comparable to those of most currently prepared gels.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] This invention utilizes PTFE to undergo directional freezing followed by soaking in a mixed solution of Hofmeister salt and an antifreeze agent, thereby enhancing the mechanical properties of the gel while imparting antifreeze properties. Overall, the preparation process is simpler, easier to operate, and less time-consuming. Furthermore, the Hofmeister effect salt can further enhance the mechanical properties of the gel, resulting in superior mechanical properties and increased strength. This invention provides a simple and universal strategy for designing conventional hydrogels, significantly improving the mechanical properties in parallel-oriented structural directions and endowing the hydrogel with fatigue resistance and extreme environmental tolerance. Hydrogels synthesized using this strategy can withstand tens of thousands of tensile cycles without fracture, while the solvent displacement effect greatly broadens the application range of the gel, potentially providing key materials for the design of hydrogel-based electronic devices. This strategy is universally applicable to various hydrogel materials, and the synthesis strategy has strong versatility.

[0034] Obviously, based on the above description of the present invention, and according to common technical knowledge and conventional methods in the field, various other modifications, substitutions or alterations can be made without departing from the basic technical concept of the present invention.

[0035] The following detailed embodiments further illustrate the above-described content of the present invention. However, this should not be construed as limiting the scope of the present invention to the following examples. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the stretching process of the fatigue-resistant conductive hydrogel in the orientation structure direction in Example 32. Detailed Implementation

[0037] The raw materials and equipment used in the specific embodiments of the present invention are all known products, obtained by purchasing commercially available products.

[0038] (1) The raw material information used in this invention is as follows:

[0039] Chitosan, hyaluronic acid, sodium alginate, sorbitol, and other gel matrix raw materials (polyethylene glycol, alginate, and cellulose, etc.), Shanghai Maclean Biochemical Technology Co., Ltd.; MAX phase powder (Nb4AlC3, Ti3CNT) x ,

[0040] Ti2CT x Ti3AlT xV2AlC, Mo2Ti2AlC3), Foshan Xinxi Technology Co., Ltd.; Graphene, silver nanowires, single-walled carbon nanotubes, Nanjing Xianfeng Nanomaterials Technology Co., Ltd.; Salts (magnesium sulfate, magnesium chloride, and sodium carbonate, etc.), antifreeze agents (propanol, ethanol, ethylene glycol, etc.), hydrochloric acid, lithium fluoride, glutaraldehyde, etc., Chengdu Kelong Chemicals Co., Ltd.

[0041] (2) The equipment information used in this invention is as follows:

[0042] Universal Testing Machine 5567, Instron Corporation, USA.

[0043] Example 1

[0044] First, a gelatin solution was mixed with silver nanowires, with the gelatin solution concentration controlled at 15 wt% and the silver nanowire concentration at 2 mg / mL. The mixture was stirred evenly and then injected into a PTFE mold. The mold was then placed in liquid nitrogen for directional freezing to obtain a gelatin / silver nanowire mixture.

[0045] A gelatin / silver nanowire mixture was immersed in a 50 mL solution of sodium chloride and ethylene glycol for 48 h to obtain a gelatin / silver nanowire hydrogel. The sodium chloride concentration was 3 M, and the ethylene glycol weight percentage was 40 wt%. The mixed solution was pre-cooled at 2℃-8℃ for 2 h, and the immersion temperature was 2℃-8℃. The test performance is shown in Table 1.

[0046] Examples 2-6 were prepared according to the method in Example 1. The selection of gel matrix solutions is shown in Table 1, and the test performance is shown in Table 1.

[0047] Example 7

[0048] First, a cellulose solution was mixed with silver nanowires, with the concentration of the cellulose solution controlled at 15 wt% and the concentration of the silver nanowires at 2 mg / mL. The mixture was stirred evenly and then injected into a PTFE mold. The mold was then placed in liquid nitrogen for directional freezing to obtain a cellulose / silver nanowire mixture.

[0049] A cellulose / silver nanowire mixture was immersed in a 50 mL solution of sodium carbonate and propylene glycol for 80 h to obtain a cellulose / silver nanowire hydrogel. The sodium carbonate concentration was 4 M, and the propylene glycol weight percentage was 45 wt%. The mixed solution was pre-cooled at 2℃-8℃ for 2 h, and the immersion temperature was 2℃-8℃. The test performance is shown in Table 1.

[0050] Examples 8-13 were prepared according to the method of Example 7, with other raw material parameters as shown in Table 1, and test performance is shown in Table 1.

[0051] Example 14

[0052] First, chitosan solution and titanium monoxide are mixed, with the chitosan solution concentration controlled at 10 wt% and the titanium monoxide concentration at 0.5 mg / mL. The mixture is stirred evenly and then poured into a PTFE mold. The mold is then placed in liquid nitrogen for directional freezing to obtain a chitosan / titanium monoxide mixture.

[0053] A chitosan / titanium monoxide mixture was immersed in a 50 mL solution of sodium thiosulfate and diethylene glycol for 24 h to obtain a chitosan / titanium monoxide hydrogel. The concentration of sodium thiosulfate was 3 M, and the weight percentage of diethylene glycol was 30 wt%. The mixed solution was pre-cooled at 2℃-8℃ for 2 h, and the immersion temperature was 2℃-8℃. The test performance is shown in Table 1.

[0054] Examples 15-18 were prepared according to the method of Example 14, with other raw material parameters as shown in Table 1, and test performance is shown in Table 1.

[0055] Example 19

[0056] First, the polyacrylamide solution was mixed with Ti3CNT. x The suspension was mixed, and the concentration of the polyacrylamide solution was controlled at 20 wt%. Ti3CNT x The concentration was 3 mg / mL, stirred thoroughly, and then injected into a PTFE mold. The mold was then placed in liquid nitrogen for directional freezing to obtain acrylamide / Ti3CNT. x mixture.

[0057] Acrylamide / Ti3CNT x The mixture was immersed in a 50 mL solution of lithium chloride and ethylene glycol for 96 h to obtain acrylamide / Ti3CNT. x Hydrogel. The concentration of lithium chloride was 4M, and the weight percentage of ethylene glycol was 30wt%. The mixed solution was pre-cooled at 2℃-8℃ for 2h, and the immersion temperature was 2℃-8℃. The test performance is shown in Table 1.

[0058] Examples 20-23 were prepared according to the method of Example 19, with other raw material parameters as shown in Table 1, and test performance is shown in Table 1.

[0059] Example 24

[0060] First, a polyethylene glycol solution and carbon nanotubes are mixed, with the polyethylene glycol solution concentration controlled at 10 wt% and the carbon nanotube concentration at 1.5 mg / mL. The mixture is stirred evenly and then injected into a PTFE mold. The mold is then placed in liquid nitrogen for directional freezing to obtain a polyethylene glycol / carbon nanotube mixture.

[0061] A polyethylene glycol / carbon nanotube mixture was immersed in a 50 mL solution of sodium carbonate and acetone glycerol for 96 h to obtain a polyethylene glycol / carbon nanotube hydrogel. The sodium carbonate concentration was 3 M, and the acetone glycerol weight percentage was 30 wt%. The mixed solution was pre-cooled at 2℃-8℃ for 2 h, and the immersion temperature was 2℃-8℃. The test performance is shown in Table 1.

[0062] Examples 25-28 were prepared according to the method of Example 24, with other raw material parameters as shown in Table 1, and test performance is shown in Table 1.

[0063] Example 29

[0064] First, a gelatin solution and graphene are mixed, with the gelatin solution concentration controlled at 15 wt% and the graphene concentration at 1.0 mg / mL. The mixture is stirred evenly and then injected into a PTFE mold. The mold is then placed in liquid nitrogen for directional freezing to obtain a gelatin / graphene mixture.

[0065] A gelatin / graphene mixture was immersed in a 50 mL solution of ammonium sulfate and glycerol for 48 h to obtain a gelatin / graphene hydrogel. The concentration of ammonium sulfate was 0.05 M, and the mass percentage of glycerol was 20 wt%. The mixed solution was pre-cooled at 2℃-8℃ for 2 h, and the immersion temperature was 2℃-8℃. The test performance is shown in Table 1.

[0066] Examples 29-34 were prepared according to the method of Example 29, with other raw material parameters as shown in Table 1, and test performance is shown in Table 1.

[0067] Example 35

[0068] First, the polyoxyethylene solution was mixed with Ti2CT. x The suspension was mixed, and the concentration of the polyoxyethylene solution was controlled at 15 wt%. Ti2CT x A solution with a concentration of 3 mg / mL was stirred thoroughly and injected into a PTFE mold. It was then placed in liquid nitrogen for directional freezing to obtain a polyoxyethylene solution / Ti2CT. x mixture.

[0069] A polyoxyethylene solution / Ti2CTx mixture was immersed in a 50 mL solution of sodium sulfate and ethylene glycol butyl ether for 3 h to obtain a polyoxyethylene solution / Ti2CTx hydrogel. The sodium sulfate concentration was 2 M, and the ethylene glycol butyl ether mass percentage was 60 wt%. The mixed solution was pre-cooled at 2℃-8℃ for 2 h, and the immersion temperature was 2℃-8℃. Test performance is shown in Table 1.

[0070] Examples 36-40 were prepared according to the method of Example 35, with other raw material parameters as shown in Table 1, and test performance is shown in Table 1.

[0071] Comparative Example 1

[0072] First, a polyacrylic acid solution was mixed with silver nanowires, with the concentration of the polyacrylic acid solution controlled at 15 wt% and the concentration of the silver nanowires at 2 mg / mL. The mixture was stirred evenly and then injected into a PTFE mold. The mold was then placed in liquid nitrogen for directional freezing to obtain a polyacrylic acid / silver nanowire mixture.

[0073] A polyacrylic acid / silver nanowire mixture was immersed in a 50 mL solution of sodium chloride and ethylene glycol for 48 h to obtain a polyacrylic acid / silver nanowire hydrogel. The sodium chloride concentration was 3 M, and the ethylene glycol mass percentage was 40 wt%. The mixed solution was pre-cooled at 2℃-8℃ for 2 h, and the immersion temperature was 2℃-8℃. The test performance is shown in Table 1.

[0074] Comparative Example 2

[0075] All-weather fatigue-resistant conductive hydrogels were prepared using the same method as Comparative Example 1, except that the gel matrix solution was a collagen solution. All other conditions were the same as in Comparative Example 1, and the test performance is shown in Table 1.

[0076] Comparative Example 3

[0077] First, the cellulose solution was diluted to a concentration of 15 wt%, stirred thoroughly, and poured into a PTFE mold. It was then subjected to directional freezing in liquid nitrogen, followed by immersion in a 50 mL mixed solution of sodium carbonate and propylene glycol for 48 h to obtain a cellulose hydrogel. The sodium carbonate concentration was 3 M, and the propylene glycol mass percentage was 40 wt%. The mixed solution was pre-cooled at 2℃-8℃ for 2 h, and the immersion temperature was 2℃-8℃. Test performance is shown in Table 1.

[0078] Comparative Example 4

[0079] All-weather fatigue-resistant conductive hydrogels were prepared using the same method as Comparative Example 3, except that after directional freezing, they were soaked in pure propylene glycol solution for 48 hours. Other conditions were the same as those in Comparative Example 3, and the properties are shown in Table 1.

[0080] Comparative Example 5

[0081] All-weather fatigue-resistant conductive hydrogels were prepared using the same method as Comparative Example 3, except that the antifreeze agent was acetone glycerol, and the other conditions were the same as those in Comparative Example 3. The properties are shown in Table 1.

[0082] Comparative Example 6

[0083] First, the chitosan solution was diluted to a concentration of 10 wt%, stirred evenly, and poured into a PTFE mold. It was then subjected to directional freezing in liquid nitrogen, followed by immersion in a 50 mL mixed solution of sodium thiosulfate and diethylene glycol for 24 h to obtain chitosan hydrogel. The sodium thiosulfate concentration was 3 M, and the diethylene glycol mass percentage was 40 wt%. The mixed solution was pre-cooled at 2℃-8℃ for 2 h, and the immersion temperature was 2℃-8℃. Test performance is shown in Table 1.

[0084] Comparative Example 7

[0085] First, the polyacrylamide solution was diluted to a concentration of 20 wt%, stirred evenly, and poured into a PTFE mold. It was then placed in liquid nitrogen for directional freezing, and subsequently immersed in a 50 mL mixed solution of sodium bicarbonate and ethylene glycol for 96 h to obtain a polyacrylamide hydrogel. The sodium bicarbonate concentration was 3 M, and the ethylene glycol mass percentage was 30 wt%. The mixed solution was pre-cooled at 2℃-8℃ for 2 h, and the immersion temperature was 2℃-8℃. Test performance is shown in Table 1.

[0086] Comparative Example 8

[0087] First, the polyethylene glycol solution was diluted to a concentration of 20 wt%, stirred thoroughly, and poured into a PTFE mold. It was then placed in liquid nitrogen for directional freezing, followed by immersion in a 50 mL solution of sodium carbonate and acetone glycerol for 96 h to obtain a polyethylene glycol hydrogel. The sodium carbonate concentration was 3 M, and the acetone glycerol mass percentage was 30 wt%. The mixed solution was pre-cooled at 2℃-8℃ for 2 h, and the immersion temperature was 2℃-8℃. Test performance is shown in Table 1.

[0088] Comparative Example 9

[0089] All-weather fatigue-resistant conductive hydrogels were prepared using the same method as Comparative Example 8, except that the salt exhibiting the Hofmeister effect in the mixed solution was calcium chloride. Other conditions were the same as in Comparative Example 8, and the test performance is shown in Table 1.

[0090] Comparative Example 10

[0091] First, a polyethylene glycol solution and carbon nanotubes are mixed, with the polyethylene glycol solution concentration controlled at 20 wt% and the carbon nanotube concentration at 2 mg / mL. The mixture is stirred evenly and then injected into a PTFE mold. The mold is then placed in liquid nitrogen for directional freezing to obtain a polyethylene glycol / carbon nanotube mixture.

[0092] A polyethylene glycol / carbon nanotube mixture was immersed in 50 mL of sodium carbonate solution for 96 h to obtain a polyethylene glycol / carbon nanotube hydrogel. The sodium carbonate concentration was 3 M. The mixed solution was pre-cooled at 2℃-8℃ for 2 h, and the immersion temperature was 2℃-8℃. The test performance is shown in Table 1.

[0093] Comparative Example 11

[0094] All-weather fatigue-resistant conductive hydrogels were prepared according to the method of Comparative Example 10, with the only difference being that after directional freezing, they were soaked in pure acetone glycerol solution for 96 hours. Other conditions were the same as those of Comparative Example 8, and the test performance is shown in Table 1.

[0095] Comparative Example 12

[0096] First, the gelatin solution was mixed with Ti3CNT. x Mix, controlling the gelatin solution concentration to 15 wt%, Ti3CNT x The gelatin / Ti3CNT mixture was prepared at a concentration of 1 mg / mL, stirred thoroughly, and then injected into a PTFE mold. It was then placed in liquid nitrogen for directional freezing to obtain gelatin / Ti3CNT. x mixture.

[0097] gelatin / Ti3CNT x The mixture was immersed in a 50 mL solution of ammonium sulfate and glycerol for 48 h to obtain gelatin / Ti3CNT. x Hydrogel. The concentration of ammonium sulfate was 1M, and the mass percentage of glycerol was 20%. The mixed solution was pre-cooled at 2℃-8℃ for 2 hours, and the immersion temperature was 2℃-8℃. The test performance is shown in Table 1.

[0098] Comparative Example 13

[0099] All-weather fatigue-resistant conductive hydrogels were prepared using the same method as Comparative Example 12, except that the conductive filler was graphene and the hydrogels were immersed in 1M ammonium sulfate solution for 48 hours after directional freezing. Other conditions were the same as those in Comparative Example 12. The test performance is shown in Table 1.

[0100] Comparative Example 14

[0101] First, the polyoxyethylene solution was mixed with Ti2CT. x Mix, control the concentration of polyoxyethylene solution to 15wt%, Ti2CT x A concentration of 3 mg / mL was stirred thoroughly and injected into a PTFE mold, then placed in liquid nitrogen for directional freezing to obtain polyoxyethylene / Ti2CT. x mixture.

[0102] Polyoxyethylene / Ti2CT x The mixture was immersed in 50 mL of propylene glycol for 48 h to obtain polyoxyethylene / Ti2CT. x Hydrogel. The mixed solution was pre-cooled at 2℃-8℃ for 2 hours, and the immersion temperature was 2℃-8℃. The test performance is shown in Table 1.

[0103] Comparative Example 15

[0104] All-weather fatigue-resistant conductive hydrogels were prepared using the same method as Comparative Example 14, except that no conductive filler was added to the gel matrix, and after directional freezing, the hydrogels were immersed in a 50 mL solution of sodium sulfate and propylene glycol for 48 h. The concentration of sodium sulfate was 3 M, the mass percentage of propylene glycol was 60%, and other conditions were the same as in Comparative Example 14. The test performance is shown in Table 1.

[0105] Hydrogels were prepared according to the above method, and then their performance was tested. The experimental results are shown in Table 1.

[0106] The mechanical performance evaluation criteria are as follows:

[0107]

[0108] In the mechanical property evaluation rating, the more asterisks (*) there are, the better the gel's mechanical properties. The electrical conductivity evaluation criteria are as follows:

[0109] Non-conductive -

[0110] Poor electrical conductivity +

[0111] Electrical conductivity is generally ++

[0112] Good electrical conductivity +++

[0113] Excellent electrical conductivity++++

[0114] Excellent electrical conductivity +++++

[0115] In the conductivity evaluation rating, the more "+" signs there are, the better the gel's conductivity. For freeze-thaw resistance evaluation: non-freeze-resistant properties are indicated by "--", and freeze-thaw-resistant properties are indicated by "√".

[0116] Table 1 Performance Summary

[0117]

[0118]

[0119]

[0120] The above results indicate that the fatigue resistance of the gel is optimal when directional freezing and salting-out are combined. The fatigue resistance of the gel prepared by directional freezing to construct the oriented structure or by promoting the lateral aggregation of polymer chain molecules to form hydrophobic regions through salting-out is far lower than that of the hydrogel prepared by directional freezing and salting-out.

[0121] in, Figure 1This is a schematic diagram of the stretching process of the fatigue-resistant conductive hydrogel in Example 32 along its oriented structure. The oriented structure on the surface of the gel material can be clearly observed. During the stretching process, the hydrogel exhibits significant crack passivation ability, that is, the notch propagation is not obvious during stretching. At the same time, obvious collagen fiber structure is observed during stretching, which provides a key opportunity to achieve high strength, toughness and tensile properties.

[0122] In summary, this invention provides a novel design strategy for fatigue-resistant conductive hydrogels. Through salting out and simultaneous solvent displacement, it significantly broadens the application range of the gel while improving mechanical properties. In practical applications, the hydrogel slows down the evaporation of water molecules over time or their freezing at zero temperatures, maintaining a certain level of mechanical toughness and conductivity, and ensuring the performance stability of the hydrogel-based electronic devices. The fatigue resistance allows the gel to withstand tens of thousands of cycles without fracture, maintaining some mechanical properties, thus providing a key material for the development of flexible electronics.

Claims

1. An all-weather fatigue-resistant conductive hydrogel, characterized in that: It is prepared by using gel matrix solution and conductive filler as raw materials, obtaining a mixture after directional freezing, and then immersing it in a mixed solution of salt and antifreeze with Hofmeister effect; the immersion time is 24 h-96 h. The gel matrix is ​​15 wt% cellulose; the conductive filler is 2 mg / mL silver nanowires; the salt exhibiting the Hofmeister effect is 3 M NaCl; and the antifreeze agent is ethylene glycol; or... The gel matrix is ​​15 wt% cellulose; the conductive filler is 2 mg / mL titanium monoxide; the salt exhibiting the Hofmeister effect is 4 M Na₂CO₃; and the antifreeze agent is propylene glycol; or... The gel matrix is ​​10 wt% chitosan; the conductive filler is 2 mg / mL titanium monoxide; the salt exhibiting the Hofmeister effect is 3 M Na₂S₂O₃; and the antifreeze agent is diethylene glycol; or... The gel matrix is ​​15 wt% gelatin; the conductive filler is 1 mg / mL graphene; the salt exhibiting the Hofmeister effect is 4 M (NH4)2SO4; and the antifreeze agent is glycerol; or... The gel matrix is ​​15 wt% polyoxyethylene; the conductive filler is Ti2CT. x 3 mg / mL, wherein the salt exhibiting the Hofmeister effect is 2 M Na2SO4, and the antifreeze agent is ethylene glycol butyl ether.

2. The method for preparing an all-weather fatigue-resistant conductive hydrogel according to claim 1, characterized in that: It includes the following steps: a. After the gel matrix solution and conductive filler are mixed evenly, the mixture is injected into a PTFE mold and then directionally frozen under liquid nitrogen to obtain the mixture; b. Immerse the mixture from step a in a mixed solution of salt and antifreeze with the Hofmeister effect, and soak it to obtain an all-weather fatigue-resistant conductive hydrogel.

3. The method for preparing the all-weather fatigue-resistant conductive hydrogel according to claim 2, characterized in that: The antifreeze mixture is composed of the following components by weight percentage: 10wt%-80wt% antifreeze and 90wt%-20wt% deionized water solvent.

4. The preparation method of the all-weather fatigue-resistant conductive hydrogel according to claim 3, characterized in that: The antifreeze mixture is composed of the following components by weight percentage: Antifreeze 30wt%-70wt%, deionized water solvent 70wt%-30wt%.

5. The method for preparing the all-weather fatigue-resistant conductive hydrogel according to claim 4, characterized in that: The antifreeze mixture is composed of the following components by weight percentage: Antifreeze 30wt%-65wt%, deionized water solvent 70wt%-35wt%.

6. The method for preparing the all-weather fatigue-resistant conductive hydrogel according to claim 2, characterized in that: The soaking temperature is -20℃ to 25℃.

7. The method for preparing the all-weather fatigue-resistant conductive hydrogel according to claim 6, characterized in that: The immersion temperature is -20℃ to 20℃.

8. The method for preparing the all-weather fatigue-resistant conductive hydrogel according to claim 7, characterized in that: The soaking temperature is -20℃ to 10℃.

9. The method for preparing the all-weather fatigue-resistant conductive hydrogel according to claim 2, characterized in that: The mixture of salt and antifreeze with the Hofmeister effect is pre-cooled at -20°C to 10°C for 0.5 h to 5 h.

10. The application of the hydrogel according to claim 1 in the preparation of sensors, triboelectric nanogenerators, and artificial ligaments.

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