Cellulose-based conductive hydrogel based on HofMichael effect as well as preparation method and application of cellulose-based conductive hydrogel

Abstract

The invention relates to the technical field of cellulose hydrogel materials, in particular to cellulose-based conductive hydrogel based on the Hall Michael effect and a preparation method and application thereof.The method includes the steps that firstly, an original physical cross-linked network of water cellulose crystals is broken through inorganic salt, and electrostatic repulsion is reduced; as new hydrogen bonds are formed among molecules, the molecules are gathered and precipitated. The phenomenon can hinder metal salt ions and CNF from being reintegrated into a homogeneous system. Therefore, the completeness of a polymerization network in the hydrogel is further adjusted by means of exogenous hydrogen bonds, a compact physical cross-linked network and a porous 3D nano-structure are formed, meanwhile, ions tend to be fixed on a polymer chain through dipole interaction, chain segments with positive electricity and negative electricity are caused, in addition, physical cross-linking can be generated through entanglement of the chain segments, and therefore the hydrogel has the advantages of being capable of being used for preparing a 3D nano-structure. The mechanical property of the hydrogel matrix is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of cellulose hydrogel materials, and particularly to a cellulose-based conductive hydrogel based on the Hofmeister effect, its preparation method and application. Background Art

[0002] With the advent of the era of artificial intelligence, the wide application of flexible and stretchable sensors in the fields of wearable devices, human-machine interfaces, intelligent robots, electronic skin, and real-time healthcare monitoring has received extensive attention. Traditional stretchable sensors mainly achieve their stretchability by bending metal films into different shapes or structures such as serpentine, reticular, and longitudinal waves. These sensors have the advantage of high conductivity, but also have many disadvantages, including complex preparation processes and poor durability. This limits their application in various fields. Among them, the three-dimensional network structure hydrogel with hydrophilicity is an ideal candidate material for flexible and wearable sensors due to its good viscoelasticity, transparency, and biocompatibility.

[0003] In recent years, researchers have made many attempts to improve the mechanical properties of hydrogels, including double-network structures, topological slip-ring gels, tetra-polyethylene glycol gels, and nanocomposite (NC) hydrogels. Among them, NC hydrogels are considered the preferred solution for enhancing mechanical properties by preventing the formation and propagation of cracks. Compared with inorganic nanoparticles, cellulose nanofibers (CNFs) have an extremely high aspect ratio, which is beneficial to form strong physical entanglements and cohesive networks in the gel matrix, endowing the gel structure with mechanical stability and better compatibility. On the other hand, CNF-reinforced hydrogel materials usually have a nanoporous structure, which can adsorb more ions, provide more space as channels for ion migration, and promote ion migration, thus significantly improving the ionic conductivity of the composite hydrogel. Generally speaking, gel networks can occur through two mechanisms: chemical crosslinking and physical crosslinking. Using chemical crosslinking agents to introduce covalent interactions in polymer chains is a conventional method to endow gels with stable structures and cohesion. By forming covalent bonds between polymer chains, a robust and stable network is established, thereby enhancing the structural integrity and mechanical properties of the gel.

[0004] However, as the number of covalent bonds in the gel increases, the polymer chains become harder and have a worse ability to deform under stress, resulting in a brittle structure, loss of elasticity and flexibility. Moreover, when the environmental temperature is below the freezing point, the water molecules in the hydrogel network are often inevitably frozen, which not only limits their ion transport ability, but also makes them hard and brittle, thus severely limiting the application of hydrogel materials in the low-temperature range. Summary of the Invention

[0005] Aiming at the deficiencies of the above-mentioned existing technologies, the purpose of the present invention is to provide a Hofmeister effect-based cellulose-based conductive hydrogel, its preparation method and application. Inspired by the Hofmeister effect, the present invention reports a multi-crosslinked stretchable cellulose-based conductive hydrogel, which consists of a covalent crosslinking network generated by free radical polymerization, multiple hydrogen bond interactions formed by encapsulated cellulose and exogenous hydrogen bonds, and coordination interactions between cations and cellulose. Therefore, the conductive hydrogel exhibits a wide strain detection range, high strain sensitivity, fast response, long-term stability and durability in strain sensor applications, and can be used to monitor various activities at different scales in the human body.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions: A preparation method of a Hofmeister effect-based cellulose-based conductive hydrogel, comprising the following steps: Extract cellulose nanofibers from raw fibers.

[0007] Under alkaline conditions, use polyphenols containing catechol groups to coat and encapsulate the cellulose nanofibers, provide more covalent / non-covalent crosslinks, form dynamic coordination bonds, and endow it with repair properties to obtain an encapsulated cellulose nanofiber solution.

[0008] Mix the encapsulated cellulose nanofiber solution with an inorganic salt ion component, break the original physical crosslinking network of the cellulose nanofiber crystal through the inorganic salt, form new hydrogen bonds between molecules, and precipitate the molecular chains to obtain a first mixed solution.

[0009] Add exogenous hydrogen bonds to the first mixed solution to adjust the integrity of the polymerization network inside the hydrogel, form a dense physical crosslinking network and a porous 3D structure to obtain a second mixed solution.

[0010] Under a nitrogen purge environment, mix the monomer, crosslinking agent and initiator with the second mixed solution evenly to obtain a homogeneous precursor solution. Pour the precursor solution into a mold and polymerize it under ultraviolet light or heating conditions to obtain a Hofmeister effect-based cellulose-based conductive hydrogel.

[0011] Inspired by the Hofmeister effect, the present invention first breaks the original physical crosslinking network of cellulose crystals through inorganic salts and reduces electrostatic repulsion. Since new hydrogen bonds are formed between molecules and aggregation and precipitation occur between the cellulose networks, this phenomenon hinders the re-integration of metal salt ions and CNFs into the homogeneous system. Therefore, by means of exogenous hydrogen bonds, forming a hydrogen bond network through competition with CNF chains helps to convert free water into bound water, further adjusting the polymerization network inside the hydrogel, thereby endowing the hydrogel with extraordinary tolerance to various harsh conditions. At the same time, ions also tend to be fixed on the polymer chains through dipole interactions, forming positively and negatively charged segments. In addition, the entanglement of these segments generates physical crosslinks and further improves the mechanical properties of the hydrogel matrix.

[0012] In a preferred embodiment of the present invention, the polyphenol containing catechol groups is tannic acid or dopamine, and the inorganic ion is Ca 2+ 、Fe 3+ 、Al 3+ 、Cu 2+ 、Zn 2+ 、Na + 、Li + 、Mg 2+ or one or more of them.

[0013] In a preferred embodiment of the present invention, the exogenous hydrogen bond includes one of sorbitol, glycerol, proline, betaine, methacryloylethyl sulfobetaine, urea, oxalic acid, methylurea or citric acid.

[0014] In a preferred embodiment of the present invention, the mass ratio of the inorganic salt ion component to the encapsulated cellulose nanofiber solution and the inorganic salt ion component is 1:5 to 30.

[0015] In a preferred embodiment of the present invention, the mass percentage of the exogenous hydrogen bond in the first mixed solution is 1% to 10%.

[0016] In a preferred embodiment of the present invention, the mass ratio of the monomer, crosslinking agent and initiator is 1 to 5:0.001 to 0.01:0.005 to 0.1, and the mass ratio of the monomer to the second mixed solution is 1 to 5:1 to 5.

[0017] In a preferred embodiment of the present invention, the method for extracting cellulose nanofibers from raw fibers includes preparing cellulose nanofibers by ring-opening oxidation, preparing cellulose nanofibers by dissolution in an organic solvent system, preparing cellulose nanofibers by dissolution in a TEMTO oxidation system or preparing cellulose nanofibers by dissolution in an ionic liquid system.

[0018] In a preferred embodiment of the present invention, the raw fibers include one or more of cotton pulp, pine pulp, softwood pulp board, hardwood pulp board and wheat straw.

[0019] Another object of the present invention is to provide a Hofmeister effect-based cellulose-based conductive hydrogel prepared by the preparation method described in any one of the above.

[0020] A third object of the present invention is to provide an application of the Hofmeister effect-based cellulose-based conductive hydrogel described above in the fields of bioelectrodes, wearable devices, human motion monitoring, and electromagnetic wave absorption.

[0021] In a preferred embodiment of the present invention, the method for extracting cellulose nanofibers from raw fibers comprises the following steps: Soak the raw cellulose in an acid catalyst, then perform a dispersion treatment, end the reaction with distilled water, and then perform filtration and dehydration to obtain dehydrated cellulose. Add water to the dehydrated cellulose to obtain a cellulose suspension, add NaIO4 and a metal salt to the cellulose suspension, mix and stir to obtain cellulose nanofibers.

[0022] In a preferred embodiment of the present invention, the dosage ratio of the raw fiber to the acid catalyst is 1 g: 10 mL to 50 mL, and the concentration of the acid catalyst is 1 mmol to 10 mmol.

[0023] In a preferred embodiment of the present invention, the mass ratio of the dehydrated cellulose to NaIO4 is 1: 1 to 10, the concentration of NaIO4 is 1 mmol to 50 mmol, and the water content of the dehydrated cellulose is 1% to 10%.

[0024] In a preferred embodiment of the present invention, the molar ratio of glucose units to the metal salt in the dehydrated cellulose is 1: 10 to 100.

[0025] Petroleum-derived synthetic polymers are very popular and play an important role in human daily life because they can be customized to meet the daily needs of life. Given the inherent non-degradability of these polymers and their dependence on petroleum resources, which have serious long-term effects on the environment, there is an urgent need to develop alternative and sustainable innovative materials. Cellulose, as a renewable resource in nature that is inexhaustible, is the oldest and most abundant natural polymer on Earth. Due to its renewability, availability, non-toxicity, low cost, environmental friendliness, and biodegradability, it is a promising alternative to petroleum-derived synthetic polymers.

[0026] Compared with the prior art, the beneficial effects of the present invention are: 1. The cellulose-based conductive hydrogel based on the Hofmeister effect of the present invention extracts cellulose nanofibers from raw fibers, and under alkaline conditions, uses polyphenols containing catechol groups to coat and encapsulate the cellulose nanofibers on the surface, providing more covalent / non-covalent crosslinks, forming dynamic coordination bonds, endowing it with repair properties, and obtaining an encapsulated cellulose nanofiber solution. Mix the encapsulated cellulose nanofiber solution with inorganic salt ion components. The inorganic salt breaks the original physical crosslinking network of the cellulose nanofiber crystals, new hydrogen bonds are formed between molecules, and molecular chains precipitate. Then, exogenous hydrogen bonds are added to adjust the integrity of the polymerization network inside the hydrogel, forming a dense physical crosslinking network and a porous 3D structure. Finally, monomers, crosslinking agents, and initiators are added and mixed evenly under a nitrogen purge environment to obtain a homogeneous precursor solution. The precursor solution is poured into a mold and polymerized under ultraviolet light or heating conditions to obtain a cellulose-based conductive hydrogel based on the Hofmeister effect. Inspired by the Hofmeister effect, the present invention first uses inorganic salts to break the original physical crosslinking network of cellulose crystals and reduce electrostatic repulsion. Since new hydrogen bonds will be formed between molecules and aggregation and precipitation will occur between the cellulose networks, this phenomenon will hinder the re-integration of metal salt ions and CNFs into the homogeneous system. Therefore, by competing with CNF chains to form hydrogen bond networks with exogenous hydrogen bonds, it helps to convert free water into bound water, further adjust the polymerization network inside the hydrogel, thereby endowing the hydrogel with extraordinary tolerance to various harsh conditions. At the same time, ions also tend to be fixed on the polymer chains through dipole interactions, forming positively and negatively charged segments. In addition, the entanglement of these segments will generate physical crosslinks and further improve the mechanical properties of the hydrogel matrix.

[0027] 2. Inspired by the Hofmeister effect, the present invention reports a multi-crosslinked stretchable cellulose-based conductive hydrogel, which is composed of a covalent crosslinking network generated by free radical polymerization, multiple hydrogen bond interactions formed by encapsulated cellulose and exogenous hydrogen bonds, and coordination interactions between cations and cellulose. Therefore, the conductive hydrogel exhibits a wide strain detection range, high strain sensitivity, fast response, long-term stability, and durability in strain sensor applications, and can be used to monitor various activities at different scales in the human body. Description of the Drawings

[0028] Figure 1 The Nyquist curves of the cellulose hydrogel prepared in Example 1 of the present invention at different temperatures.

[0029] Figure 2 The CV curves of the cellulose hydrogel prepared in Example 1 of the present invention at different temperatures.

[0030] Figure 3The tensile-recovery resistance signal curve of the cellulose hydrogel prepared in Example 1 of the present invention after 2000 cycles under a 30% strain condition. Detailed implementation manners

[0031] The following combines the embodiments of the present invention, and uses preferred embodiments and accompanying drawings for detailed description. The technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0032] It should be noted that all the professional terms used in the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the protection scope of the present invention. Unless otherwise specifically stated, various raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be obtained through market purchase or prepared by existing methods.

[0033] Example 1 A preparation method of a cellulose-based conductive hydrogel based on the Holmquist effect, comprising the following steps: (1) Take a certain mass of cotton linter cellulose and react with dilute HCl solution at a solid-liquid ratio of 1:30 at 70 °C for 90 min, and perform a dispersion treatment. Finally, add an excessive amount of distilled water to end the reaction. After standing overnight, discard the supernatant, and wash repeatedly with distilled water until the pH is close to neutral. Then filter and dry the viscous substance until the water content in the sample reaches 4%. Weigh 1 g of incompletely dried cellulose and suspend it in a NaIO4 solution containing 0.06 M, and further increase the oxidation rate of cellulose by adding LiCl salt, where the molar ratio of LiCl to glucose units is 7:1. Then transfer it to a water bath environment and heat and stir for 4 h. After the reaction is completed, take out the reaction solvent and wash it with a large amount of deionized water until neutral. Then, further oxidize it with 5.0 mmol of sodium hypochlorite in 1 M acetic acid solution. After oxidation, quench the reaction by adding an appropriate amount of ethanol, and dialyze with deionized water for one week. Finally, obtain a uniformly dispersed cellulose nanofiber (CNF) dispersion by ultrasonic defibrillation of the collected supernatant at 800 W.

[0034] (2) To manufacture the conductive hydrogel, first mix tannic acid and CNF at a mass ratio of 1:3 under alkaline conditions using a mixer for surface coating encapsulation to obtain an encapsulated cellulose nanofiber solution.

[0035] (3) Mix the encapsulated cellulose nanofiber solution and LiCl at a mass ratio of 5:1 and form a first mixed solution under high-speed stirring.

[0036] (4) Add exogenous hydrogen-bonded urea with a mass fraction of 5% to the first mixed solution, and adjust the hydrogen-bonding of the internal network of the hydrogel by introducing exogenous hydrogen-bonded urea rich in amino groups to obtain a second mixed solution.

[0037] (5) Then, under nitrogen purging, 2 g of AM, 0.05 mol / L of MBA, and 0.3 mol / L of APS were completely dissolved in the second mixed solution to form a homogeneous precursor solution, which was placed in an oven at 70 °C for polymerization for 20 min to obtain a hydrogel.

[0038] (6) To remove surface residues, the hydrogel was immersed in excess distilled water, and the apparent moisture was dried at room temperature to obtain a cellulose-based conductive hydrogel based on the Hofmeister effect.

[0039] Example 2 A preparation method of a cellulose-based conductive hydrogel based on the Hofmeister effect, comprising the following steps: (1) Take a certain mass of softwood pulp cellulose and react it with dilute HCl solution at a solid-liquid ratio of 1:20 at 60 °C for 60 min, and perform a dispersion treatment. Finally, add excess distilled water to end the reaction. After standing overnight, discard the supernatant, and wash it repeatedly with distilled water until the pH is close to neutral. Then, filter and dry the viscous substance until the moisture content in the sample reaches 3%. Weigh 1 g of incompletely dried cellulose and suspend it in a solution containing 0.04 M of NaIO4, and further increase the oxidation rate of cellulose by adding NaCl salt, where the molar ratio of NaCl to glucose unit is 8:1. Then transfer it to a water bath environment for heating and stirring for 4 h. After the reaction is completed, take out the reaction solvent and wash it with a large amount of deionized water until neutral. Then, further oxidize it with 6.0 mmol of sodium hypochlorite in 1 M acetic acid solution. After oxidation, quench the reaction by adding an appropriate amount of ethanol, and dialyze it with deionized water for one week. Finally, defibrillate the collected supernatant by 800 W ultrasound to obtain a uniformly dispersed cellulose nanofiber dispersion.

[0040] (2) To fabricate a conductive hydrogel, first mix dopamine and CNF at a mass ratio of 1:1 using a mixer for surface coating encapsulation to obtain an encapsulated cellulose nanofiber solution.

[0041] (3) Mix the encapsulated cellulose nanofiber solution with a certain amount of LiCl at a mass ratio of 10:1 and stir at high speed to form a first mixed solution.

[0042] (4) Add exogenous hydrogen-bonded glycerol with a volume fraction of 10% to the first mixed solution, and adjust the hydrogen-bonding of the internal network of the hydrogel by introducing exogenous hydrogen-bonded glycerol rich in hydroxyl groups to obtain a second mixed solution.

[0043] (5) Then, 2 g of AM, 0.02 mol / L of MBA, and 0.2 mol / L of APS were completely dissolved in the second mixed solution under nitrogen purging to form a homogeneous precursor solution, which was placed in an oven at 70 °C for polymerization for 20 min to obtain a hydrogel.

[0044] (6) To remove surface residues, the hydrogel was immersed in excess distilled water, and the apparent moisture was dried at room temperature to obtain a cellulose-based conductive hydrogel based on the Hofmeister effect.

[0045] Example 3 A preparation method of a cellulose-based conductive hydrogel based on the Hofmeister effect, comprising the following steps: (1) Weigh an appropriate amount of incompletely dried wheat straw cellulose and suspend it in water (100 mL) containing TEMPO (0.16 mmol) and sodium bromide (2 mmol). Then, 5 mmol of 11.9% sodium hypochlorite (NaClO) was added to start the TEMPO-mediated oxidation reaction; during this process, NaOH was continuously added to adjust the pH value of the solution to 10 ± 0.3. When no more pH decrease was observed, the reaction was completed. After oxidation, the reaction was quenched by adding an appropriate amount of ethanol, and the pH of the reaction was adjusted to 7 by adding 0.5 M HCl. Finally, the TEMPO oxidation product was thoroughly washed with water by filtration and stored at 4 °C. Subsequently, the washed product was redispersed in water. Then, after the dispersion was centrifuged at high speed, the precipitate was removed and the upper-layer dispersion was collected. Finally, the collected supernatant was defibrillated at a stirring rate of 35000 rpm to obtain a uniformly dispersed TEMPO-oxidized cellulose nanofiber (CNF) dispersion.

[0046] (2) To fabricate the conductive hydrogel, first, TA and CNF were mixed at a mass ratio of 2:1 using a mixer for surface coating encapsulation to obtain an encapsulated cellulose nanofiber solution.

[0047] (3) The encapsulated cellulose nanofiber solution was mixed with ZnCl2 at a mass ratio = 10:0.1, and a first mixed solution was formed under high-speed stirring.

[0048] (4) 1% exogenous hydrogen-bonded glucose by mass fraction was added to the first mixed solution, and the hydrogen-bonding of the internal network of the hydrogel was adjusted by introducing exogenous hydrogen-bonded glucose rich in hydroxyl groups to obtain a second mixed solution.

[0049] (5) Then, 2 mL of AA, 0.03 mol / L of MBA, and 0.01 mol / L of Irgacure 2959 were completely dissolved in the second mixed solution under nitrogen purging to form a homogeneous precursor solution, which was placed in an oven under ultraviolet light conditions and polymerized for 5 min to obtain a hydrogel.

[0050] (6) To remove surface residues, the hydrogel was immersed in a binary solvent of dimethyl sulfoxide and water containing ZnCl2, and finally, the apparent moisture was dried at room temperature to obtain a cellulose-based conductive hydrogel based on the Hofmeister effect.

[0051] Result Analysis Figure 1 The Nyquist curves of the cellulose hydrogel prepared in Example 1 of the present invention at different temperatures are shown as Figure 1 shown. The hydrogel exhibits an ultra-wide working range. When the working temperature drops from 80 °C to -40 °C, the resistance of the fabricated solid-state supercapacitor only increases from 5.4 Ω / CM to 40 Ω / CM. The low resistance of the device promotes the transport of ions and ensures that the prepared hydrogel has excellent electrochemical properties.

[0052] Figure 2 The CV curves of the cellulose hydrogel prepared in Example 1 of the present invention at different temperatures are shown. In the entire temperature range from -40 to 80 °C, at a scanning rate of 50 mV s −1 -1, the quasi-rectangular shape of the CV loop remains unchanged. The area of the loop in the cyclic voltammetry curve increases with the increase of the working temperature, indicating an increase in the charge storage of the hydrogel. At the same time, the hydrogel exhibits ultra-high cycle stability and still outputs sufficient temperature electrical signals under 50% strain cycling conditions.

[0053] Figure 3 The tensile-recovery resistance signal curve of the cellulose hydrogel prepared in Example 1 of the present invention after 2000 cycles under 30% strain conditions is shown. It can be seen from the figure that the hydrogel prepared in the present invention exhibits stable electrical signal transmission, indicating that the hydrogel can ensure stable output of electrical signals when used as a flexible strain sensor, ensuring the accuracy of the sensing process.

[0054] In summary, inspired by the Hofmeister effect, the present invention first uses inorganic salts to break the original physical crosslinking network of cellulose crystals and reduce electrostatic repulsion. Since new hydrogen bonds are formed between molecules and aggregation and precipitation occur between the cellulose networks, this phenomenon hinders the re-integration of metal salt ions and CNFs into the homogeneous system. Therefore, by means of exogenous hydrogen bonds, a hydrogen bond network is formed by competing with CNF chains to further adjust the polymerization network inside the hydrogel. At the same time, ions also tend to be fixed on the polymer chains through dipole interactions, forming positively and negatively charged segments. In addition, the entanglement of these segments generates physical crosslinks and further improves the mechanical properties of the hydrogel matrix. Inspired by the Hofmeister effect, the present invention reports a multi-crosslinked stretchable cellulose-based conductive hydrogel, which is composed of a covalent crosslinking network generated by free radical polymerization, multiple hydrogen bond interactions formed by encapsulated cellulose and exogenous hydrogen bonds, and coordination interactions between cations and cellulose. Therefore, the conductive hydrogel exhibits a wide strain detection range, high strain sensitivity, fast response, long-term stability and durability in strain sensor applications and can be used to monitor various activities at different scales in the human body.

[0055] It should be noted that when the present invention involves a numerical range, it should be understood that any value between the two endpoints of each numerical range and either of the two endpoints can be selected. Since the steps and methods adopted are the same as those in the embodiments, in order to prevent repetition, the present invention describes the preferred embodiments. Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be construed as including the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0056] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing a cellulose-based conductive hydrogel based on the Hofmeister effect, characterized in that: The following steps are involved: Extraction of cellulose nanofibers from raw fibers; Under alkaline conditions, polyphenols containing catechol groups are used to coat and encapsulate the surface of cellulose nanofibers to obtain an encapsulated cellulose nanofiber solution; The encapsulated cellulose nanofiber solution is mixed with an inorganic salt ion component, the inorganic salt is used to break the original physical cross-linking network of the cellulose nanofiber crystals and precipitate the molecular chains to obtain a first mixed solution; Adding exogenous hydrogen bonds to the first mixed solution to adjust the integrity of the polymer network inside the hydrogel to form a dense physical cross-linked network and a porous 3D structure, thereby obtaining a second mixed solution; The monomer, the cross-linking agent and the initiator are mixed evenly with the second mixed solution under a nitrogen purge environment to obtain a homogeneous precursor solution, the precursor solution is poured into a mold, and polymerized under ultraviolet light or heating conditions to obtain a cellulose-based conductive hydrogel based on the Hofmeister effect.

2. The method for preparing a cellulose-based conductive hydrogel based on the Hofmeister effect according to claim 1, characterized in that: Inorganic ions are Ca 2+ , Fe 3+ 、Al 3+ , Cu 2+ 、Zn 2+ 、Na + , Li + Mg 2+ One or more of .

3. The method for preparing a cellulose-based conductive hydrogel based on the Hofmeister effect according to claim 1, characterized in that: The polyphenol containing the catechol group is tannic acid or dopamine, and the exogenous hydrogen bond includes one of sorbitol, glycerol, proline, betaine, methacryloylethyl sulfobetaine, urea, oxalic acid, methylurea or citric acid.

4. The method for preparing a cellulose-based conductive hydrogel based on the Hofmeister effect according to claim 1, characterized in that: The mass ratio of the polyphenol containing catechol groups to the inorganic salt ion component and the polyphenol containing catechol groups is 1:1-3, and the mass ratio of the inorganic salt ion component to the encapsulated cellulose nanofiber solution is 1:5-30.

5. The method for preparing a cellulose-based conductive hydrogel based on the Hofmeister effect according to claim 1, characterized in that: The mass percentage of exogenous hydrogen bonds in the first mixed solution is 1% to 10%.

6. The method for preparing a cellulose-based conductive hydrogel based on the Hofmeister effect according to claim 1, characterized in that: The mass ratio of the monomer, the cross-linking agent and the initiator is 1-5: 0.001-0.01: 0.005-0.1, and the mass ratio of the monomer to the second mixed solution is 1-5: 1-5.

7. The method for preparing a cellulose-based conductive hydrogel based on the Hofmeister effect according to claim 1, characterized in that: The method of extracting cellulose nanofibers from original fibers includes preparing cellulose nanofibers by ring-opening oxidation, preparing cellulose nanofibers by dissolving in an organic solvent system, preparing cellulose nanofibers by dissolving in a TEMTO oxidation system, or preparing cellulose nanofibers by dissolving in an ionic liquid system.

8. The method for preparing a cellulose-based conductive hydrogel based on the Hofmeister effect according to claim 7, characterized in that: The raw fibers include one or more of cotton pulp, pine pulp, softwood pulpboard, hardwood pulpboard and wheat straw.

9. A cellulose-based conductive hydrogel based on the Hofmeister effect obtained by the preparation method according to any one of claims 1 to 8.

10. An application of the cellulose-based conductive hydrogel based on the Hofmeister effect according to claim 9 in the fields of bioelectrodes, wearable devices, human motion monitoring and electromagnetic wave absorption.

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