Lignin-based conductive eutectic gel as well as preparation method and application thereof

Abstract

The invention discloses conductive eutectic gel based on lignin and a preparation method and application thereof, and belongs to the technical field of intelligent soft materials.The conductive eutectic gel based on lignin is prepared from, by weight, 20-50 parts of polymerizable monomer, 0.01-0.2 part of cross-linking agent, 0.01-0.15 part of sodium lignin sulfonate, 3-6 parts of modified keratin and 0.1-1 part of initiator. 50 to 90 parts of deep eutectic solvent and 50 to 100 parts of water; the polymerizable monomer is acrylic acid and [2-(methylacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide, and the modified keratin is a polyethylene glycol-based double-end crosslinking monomer and disulfide bis (p-phenylene) bis (2-methacrylate) grafted modified keratin. The lignin-based conductive eutectic gel provided by the invention has excellent strain sensing performance, can be used for monitoring sports of different parts of a human body and personal health, has excellent adhesion performance, and can be stably combined with fitness equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of intelligent soft materials, and in particular to a lignin-based conductive eutectic gel, a preparation method thereof, and an application thereof. Background Art

[0002] Hydrogels are polymers composed of hydrophilic segments with a three-dimensional network structure. They possess outstanding electrical conductivity, flexibility, biomimetic structures, biocompatibility, and electrical stimulus responsiveness. Hydrogel-based sensors can convert chemical or biological signals into measurable electrical signals, and have broad application prospects in fields such as water treatment, environmental monitoring, biomedicine, and food safety. The application of hydrogels in flexible wearable sensors continues to expand, encompassing strain, pressure, temperature, optical, and acoustic sensors. In recent years, flexible wearable sensing systems based on hydrogel materials have demonstrated unique research value in the development of smart fitness equipment due to their excellent biocompatibility and mechanical adaptability. By integrating flexible hydrogel sensors with exercise equipment, dynamic capture of human biomechanical parameters during exercise can be achieved, providing critical data support for posture correction, training load optimization, and sports injury warning. In particular, the construction of a pressure sensing network at the foot-machine interface enables real-time analysis of the dynamic characteristics of plantar pressure distribution during exercise, which has important applications in assessing balance ability—a parameter that has been shown to be an important predictor of imbalance in strength training, the risks of equipment use in the elderly, and motor function recovery in rehabilitation patients. This data is primarily obtained through wearable pressure monitoring devices, which must be able to detect pressure changes in real time, accurately, sensitively, and reliably. However, the polymer networks of conventional conductive hydrogels generally suffer from poor mechanical properties, fragility, and poor environmental tolerance, which reduces the service life and application value of these materials. Summary of the Invention

[0003] In order to overcome the shortcomings of the above-mentioned prior art, the present invention provides a lignin-based conductive eutectic gel and its preparation method and application. The conductive eutectic gel is formed by copolymerizing SBMA, modified keratin, acrylic acid, a crosslinker, and sodium lignin sulfonate to form a hydrogel network, and a deep eutectic solvent is added for metal coordination to construct secondary dynamic crosslinking points outside the covalent network, giving the gel excellent self-healing properties, energy dissipation capacity and anti-fatigue performance.

[0004] The purpose of the present invention is to provide a lignin-based conductive eutectic gel and a preparation method and application thereof.

[0005] The present invention is achieved through the following technical solutions:

[0006] A lignin-based conductive eutectic gel comprises the following components by weight: 20-50 parts of a polymerizable monomer, 0.01-0.2 parts of a cross-linking agent, 0.01-0.15 parts of sodium lignin sulfonate, 3-6 parts of modified keratin, 0.1-1 parts of an initiator, 50-90 parts of a deep eutectic solvent, and 50-100 parts of water. The polymerizable monomers are acrylic acid and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide (SBMA), and the modified keratin is a polyethylene glycol-based double-end cross-linking monomer and disulfide di(p-phenylene) bis(2-methacrylate) grafted modified keratin.

[0007] In a specific embodiment, the polyethylene glycol-based double-end cross-linking monomer is at least one of polyethylene glycol diacrylate or polyethylene glycol dimethacrylate, and the structural formula of the disulfide di(p-phenylene) di(2-methacrylate) is shown in Formula 1:

[0008]

[0009] In a specific embodiment, the preparation of the modified keratin comprises the following steps:

[0010] S1. Using feathers and hair as raw materials, urea as solvent, and L-cysteine as reducing agent, pure keratin was extracted by the swelling-reduction method.

[0011] S2. Using tri(2-carbonylethyl)phosphine hydrochloride solution as a reducing agent, the disulfide bonds of keratin are reduced to thiol groups, and then polyethylene glycol-based double-end cross-linking monomers, disulfide di(p-phenylene)di(2-methylacrylate) and an initiator are added for graft modification to obtain modified keratin.

[0012] In a specific embodiment, the amount of the reducing solution added in step S2 is 80 wt% to 100 wt% of the keratin protein, and the amount of the polyethylene glycol-based double-end cross-linking monomer and disulfide di(p-phenylene)di(2-methacrylate) added is 60 wt% to 100 wt% of the keratin protein.

[0013] Keratin molecules are proteins with a three-dimensional network structure formed by various amino acids through disulfide bonds, peptide bonds, hydrogen bonds, etc. The high degree of cross-linking makes keratin insoluble in water, saline solutions, dilute acids or dilute alkalis, and has extremely strong resistance. The present invention uses polyethylene glycol-based double-end cross-linking monomers and hydrophilic monomers to modify keratin to improve its solubility. At the same time, the disulfide bis(p-phenylene)bis(2-methylacrylate) is added to replenish the disulfide bonds that are reduced and consumed during the keratin modification process to maintain the keratin's macromolecular structure and film-forming properties. In addition, the unconsumed alkenyl groups in the modified keratin can also polymerize with polymerizable monomers, ensuring the successful integration of the modified keratin and enhancing the cross-linking density of the hydrogel cross-linked network.

[0014] In a specific embodiment, the mass ratio of the acrylic acid and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide is (4-6):1, and the mass ratio of the polyethylene glycol-based double-end cross-linking monomer and disulfide di(p-phenylene)di(2-methacrylate) is (5-10):1.

[0015] In a specific embodiment, the initiator is selected from at least one of potassium persulfate, ammonium persulfate, and sodium sulfite; the cross-linking agent is at least one of N,N'-methylenebisacrylamide, bisacrylamide, polyethylene glycol diacrylate, or polyethylene glycol dimethacrylate; and the deep eutectic solvent is an ethylene glycol solution of ZnCl2 with a molar ratio of 1:(5-8).

[0016] Another object of the present invention is to protect a method for preparing a lignin-based conductive eutectic gel, comprising the following steps: mixing a polymerizable monomer, a cross-linking agent, sodium lignin sulfonate, modified keratin, an initiator, a deep eutectic solvent and pure water to obtain a prepolymer liquid; filling the prepolymer liquid into a mold, vigorously stirring it with ultrasound, placing it in a vacuum drying oven, and heating it at 70-90°C for 30-60 minutes to obtain a lignin-based conductive eutectic gel.

[0017] Another object of the present invention is to protect the application of the lignin-based conductive eutectic gel in sensors, biomedicine and flexible electronics.

[0018] Specifically, the conductive eutectic gel monitors human body movements through changes in electrical signal peak value and peak shape.

[0019] Beneficial effects

[0020] The present invention provides a lignin-based conductive eutectic gel, its preparation method, and application. The conductive eutectic gel is formed by copolymerizing SBMA, modified keratin, acrylic acid, a crosslinker, and sodium lignin sulfonate to form a hydrogel network, and a deep eutectic solvent is added for metal coordination. SBMA is a zwitterionic monomer with stable quaternary ammonium cations and sulfonate anions on its chain segments. This inherent zwitterionic property forms a highly hydrated ionic network in the aqueous phase and can react with the partially deprotonated carboxylic acid groups of AA and the Zn in the deep eutectic solvent. 2+ The ions significantly enhance the mechanical strength and anti-volume expansion performance of the gel through metal coordination bonds. 2+Ions can reversibly coordinate with the carboxyl, hydroxyl, and amide groups in the modified keratin molecules, constructing secondary dynamic crosslinking points outside the covalent network, giving the gel excellent self-healing properties, energy dissipation capabilities, and fatigue resistance. Modified keratin is rich in hydroxyl and amide groups, forming a dense hydrogen bond network between the polymer matrix and water molecules. These non-covalent interactions can be broken sequentially under external force loading and partially reassembled after unloading, achieving good elastic recovery. The deep eutectic solvent not only improves the solubility of each precursor and ensures uniform polymerization, but its high osmotic pressure properties also regulate the gel pore structure and water content, giving the material both excellent compressive stability and controllable environmental stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The infrared spectra of polymerizable monomer, modified keratin and conductive eutectic gel;

[0022] Figure 2 This is a surface morphology of the conductive eutectic gel of Example 1;

[0023] Figure 3 Graph showing the adhesion performance of the conductive eutectic gel of Example 1 to different substrates;

[0024] Figure 4 These are the antifreeze effect diagram and anti-drying effect diagram of the conductive eutectic gel of Example 1 at room temperature and -20°C environment.

[0025] Figure 5 This is a resistance change signal diagram of the conductive eutectic gel of Example 1 under cyclic stretching / releasing at different strains and frequencies. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0027] In the examples, the experimental methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used are all commercially available unless otherwise specified.

[0028] The raw materials used in the embodiments and comparative examples are now described as follows:

[0029] Polymerizable monomer 1: acrylic acid, 99%, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0030] Polymerizable monomer 2: [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide; 98%, purchased from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0031] Cross-linker: N,N-methylenebisacrylamide, 2% solution, purchased from Sigma-Aldrich;

[0032] Sodium lignin sulfonate: purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0033] Duck feathers: Hangzhou Yongfeng Down Products Co., Ltd.

[0034] 4,4'-Dihydroxydiphenyl disulfide: 98%, purchased from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0035] Methacryloyl chloride: 95%, Shanghai Aladdin Biochemical Technology Co., Ltd.

[0036] Initiator: ammonium persulfate, 99.99%, Shanghai Aladdin Biochemical Technology Co., Ltd.

[0037] Deep eutectic solvent: Add 2 g of zinc chloride to 5.47 g of ethylene glycol and stir in a 70-75°C hot water bath until dissolved. This creates a deep eutectic solvent with a molar ratio of ethylene glycol to zinc chloride of 6:1.

[0038] Polyethylene glycol-based double-end cross-linking monomer: polyethylene glycol dimethacrylate; Mn700, Shanghai MacLean Biochemical Technology Co., Ltd.;

[0039] Disulfide di(p-phenylene) bis(2-methacrylate): homemade, prepared as follows: in anhydrous, oxygen-free, nitrogen atmosphere, 0.1 mol of 4,4'-dihydroxydiphenyl disulfide and 0.2 mol of triethylamine were dissolved in chloroform, 0.2 mol of methacryloyl chloride was added dropwise under ice bath conditions, the temperature was slowly raised to 80°C and stirred for 6 hours until the reaction was complete, the reaction was cooled, and the reaction was quenched with ice water. The organic phase was washed with 5% NaHCO3 solution and then washed with water until neutral, concentrated under reduced pressure, and recrystallized from a mixed solvent of n-heptane / acetone to obtain disulfide di(p-phenylene) bis(2-methacrylate);

[0040] Modified keratin 1: homemade, preparation method is as follows:

[0041] S1. Duck feathers are washed and dried, then crushed to 30 mesh using a grinder for later use. 8 mol / L urea solution is used as a solvent at a bath ratio of 1:30. 10 wt.% L-cysteine reducing agent, equivalent to the weight of the duck feathers, is added. The pH value of the system is adjusted to 9 with a 5.0% mass fraction sodium hydroxide solution. The crushed duck feathers are weighed and added to the prepared extract. The mixture is reacted at 85°C for 7 hours to obtain a mixed solution. The obtained mixed solution is centrifuged and poured into a dialysis bag for 2-3 days until the pH of the keratin solution in the dialysis bag is neutral, thereby obtaining a dialyzed keratin solution. The dialyzed keratin solution is adjusted to a keratin isoelectric point of approximately 4.5-5.5 using a 1.0% mass fraction acetic acid solution to precipitate the keratin in the solution. The precipitated keratin is collected and freeze-dried to obtain a solid keratin powder.

[0042] S2. Dissolve tri(2-carbonylethyl)phosphine hydrochloride in a 1:1 volume ratio of ethanol to water to prepare a 50 mmol / L reducing agent stock solution. Weigh 0.5 g of keratin and add an amount of reducing agent stock solution equivalent to 80 wt% of the keratin mass. Adjust the pH to 7 with a Na2CO3 / NaHCO3 buffer solution (pH > 9). Reduce the solution at 20°C for 4 h.

[0043] S3. Under nitrogen protection, an initiator equivalent to 5 wt% of the keratin mass and a polyethylene glycol-based double-end cross-linking monomer and disulfide di(p-phenylene)bis(2-methacrylate) equivalent to 60 wt% of the keratin mass were added to the reduced keratin, wherein the mass ratio of the polyethylene glycol-based double-end cross-linking monomer to the disulfide di(p-phenylene)bis(2-methacrylate) was 10:1. The pH value of the system was adjusted to 7, and the reduced keratin was grafted and modified at 20°C for 4 hours to obtain modified keratin. The reaction solution was centrifuged and poured into a dialysis bag for 2-3 days to obtain a modified keratin 1 solution.

[0044] Modified keratin 2: homemade. The preparation method is similar to that of modified keratin 1. The difference is that the mass ratio of polyethylene glycol-based double-end cross-linking monomer and disulfide di(p-phenylene) bis(2-methacrylate) is 5:1.

[0045] Modified keratin 3: homemade. The preparation method is similar to that of modified keratin 1, except that no polyethylene glycol-based double-end cross-linking monomer is added.

[0046] Modified keratin 4: homemade, the preparation method is similar to that of modified keratin 1, except that disulfide di(p-phenylene) bis(2-methacrylate) is not added;

[0047] Unless otherwise specified, the components and raw materials used in the examples and comparative examples of the present invention are all commercially available raw materials, and the components and raw materials used in each parallel experiment are all of the same kind.

[0048] Examples and Comparative Examples

[0049] A conductive eutectic gel based on lignin, the weight ratio of which is shown in Table 1, and the preparation method is as follows:

[0050] 1) A polymerizable monomer, a cross-linking agent, sodium lignin sulfonate, modified keratin, an initiator, a deep eutectic solvent, and pure water are mixed to obtain a prepolymer solution; ultrasonic defoaming is performed for 10 minutes, the prepolymer solution is filled into a mold, and ultrasonic stirring is performed vigorously. The mold is placed in a vacuum drying oven and heated at 70° C. for 30 minutes to obtain a lignin-based conductive eutectic gel.

[0051] Table 1 Conductive eutectic gel based on lignin (parts by weight)

[0052]

[0053]

[0054] The following performance tests were performed on a lignin-based conductive eutectic gel prepared in the examples and comparative examples. The results are shown in the accompanying drawings and Table 2, respectively.

[0055] 1. Infrared Spectroscopy: Mix the raw materials and conductive eutectic gel with potassium bromide at a ratio of 1:50 to form a pellet. This test was performed using an Avatar 380 spectrometer. The sample was pressed into a potassium bromide pellet. Before the test, a blank background was scanned, and then the pellet sample was placed in the test. The scanning range was 500-4000 cm -1 , the results are as follows Figure 1 shown.

[0056] 2. Surface microstructure: The surface microstructure of the conductive eutectic gel obtained in Example 1 was examined using a field emission scanning electron microscope (SEM). The eutectic gel was placed in liquid nitrogen to freeze the structure and fracture, then placed in a freeze dryer to dry the moisture, and finally placed in a field emission scanning electron microscope (SEM) to observe the surface microstructure of the eutectic gel. The results are as follows: Figure 2 shown.

[0057] 3. Tensile Strength and Elongation at Break: A universal testing machine was used to test the tensile strength and elongation at break of the eutectic conductive gel. The eutectic gel was clamped neatly on the tensile testing machine at both ends, set at a tensile speed of 50 mm / min, and the stress-strain curve was recorded in real time until the eutectic gel broke.

[0058] 4. Compression Performance: A conductive eutectic gel with a diameter of 20 mm and a thickness of 3 mm was prepared and tested for its compression performance using a universal testing machine. The eutectic gel was neatly placed on the compression fixture of the tensile testing machine. The compression speed was set to 20 mm / min and the compression ratio to 90%. The stress and strain curves during this process were recorded in real time.

[0059] 5. Conductivity: A 5mm wide conductive copper foil was neatly attached to both ends of the conductive eutectic gel. The sensor was then connected to the electrochemical workstation using the conductive copper tape. The impedance information of the conductive eutectic gel at different AC frequencies was recorded in real time. The conductivity σ was finally calculated using the following formula: Where σ is the conductivity, L is the length, S is the cross-sectional area, and R is the material resistance.

[0060] 6. Adhesion performance: Prepare a conductive eutectic gel with a length of 40 mm × a width of 40 mm × a thickness of 2 mm. Select 8 different adhesive substrates, including glass, wood, plastic, PTFE, metal, silicone, ceramic and skin. Then adhere the prepared conductive eutectic gel evenly to one of the substrates. Then adhere glass to the other side of the eutectic gel, and avoid bubbles between the adhesive surfaces of the materials. Record optical pictures of the gel adhering to different substrates, such as Figure 3 shown.

[0061] 7. Antifreeze and anti-drying properties: A conductive eutectic gel with a length of 50 mm, a width of 10 mm, and a thickness of 2 mm was prepared and placed in a -20°C environment for 24 hours. The antifreeze properties of the gel were determined by observing whether it had crystallized and comparing its flexibility with that at room temperature. At the same time, the conductive eutectic gel was placed in an open room temperature environment and the mass change at 0 hours and 72 hours was compared to test the anti-drying properties of the eutectic gel. The results are as follows: Figure 4 shown.

[0062] 8. Strain sensing performance: A universal testing machine and a multimeter are used to test the strain sensing performance of the conductive eutectic gel sensor. A 5mm wide conductive copper tape is neatly attached to both ends of the conductive eutectic gel. The gel is then clamped together with the wrapped conductive copper tape on a tensile testing machine. The conductive copper tape is extended, and the sensor is connected to the multimeter with the help of the conductive copper tape. The tensile testing machine is then used to perform cyclic stretching / releasing of the sensor at different strains and frequencies, and the resistance change signal of the sensor is recorded in real time during the process, such as Figure 5 shown.

[0063] Table 2 Performance test results of conductive eutectic gel

[0064]

[0065] From the attached Figure 1It can be seen that in the spectrum of SBMA, the peak appears at 1722 cm -1 The peak value is at 1185 cm-1, which is attributed to the stretching vibration of C=O on the ester carbonyl group. -1 and 1045cm -1 It is attributed to the vibration of the sulfonic acid group, with a peak at 1643 cm -1 It is attributed to C=C vibration. In the spectrum of modified keratin, the peak appears at 3292 cm -1 The peak value is at 2958 cm-1, which is attributed to the stretching vibration of NH and CO-NH on the amide group. -1 The peak value is at 1652 cm, which is attributed to the stretching vibration of CH2. -1 The peak value is at 1528 cm, which is attributed to the stretching vibration of C=O on the amide group. -1 It is attributed to NH bending vibration and CN stretching vibration, with a peak at 1041 cm -1 It is attributed to the stretching vibration of COC. In the spectrum of AA, the peak is at 3502cm -1 and 3072cm -1 The peak value is at 1630 cm-1, which is attributed to the stretching vibration of -OH and -CH. -1 and 1704cm -1 The peaks of C=C vibration are significantly reduced in the conductive eutectic gel, and the characteristic groups of the three monomers are present, proving that SBMA, AA and modified keratin have been successfully copolymerized.

[0066] From the attached Figure 2 It can be seen that the conductive eutectic gel has a porous structure, which can provide excellent channels for ion transport and further provide a good foundation for the conductive properties of the conductive eutectic gel.

[0067] From the attached Figure 3 It can be seen that the conductive eutectic gel can adhere to the surfaces of various substrates at room temperature and withstand a certain weight without peeling off, such as plastic, glass, wood, skin, etc. This is based on the fact that the abundant carboxyl, amino, and hydroxyl groups on the surface of the hydrogel can physically interact with the materials through hydrogen bonding, ion-dipole interaction, and metal complexation. The excellent adhesion performance provides the basis for the stable acquisition of sensing electrical signals.

[0068] From the attached Figure 4 It can be seen that the conductive eutectic gel placed in a -20°C environment does not exhibit crystallization, while maintaining the same flexibility as in a room temperature environment, confirming that the eutectic gel has excellent anti-freeze properties. At the same time, the quality of the eutectic gel does not change significantly after being placed in an open environment for 72 hours, confirming that the eutectic gel has excellent anti-drying properties.

[0069] From the attached Figure 5It can be seen that when the eutectic gel sensor is subjected to cyclic stretching / release and compression / release at different strains using a universal testing machine, the peak value and peak shape of the electrical signal generated under the same strain conditions are similar, confirming that the sensing performance of the conductive eutectic gel has excellent stability, which is a very important performance for flexible sensor devices.

[0070] As can be seen from Table 2, the conductive eutectic gel has good mechanical properties and conductive properties, which can provide a basis for monitoring the changes in electrical signals of various human movements.

[0071] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A conductive eutectic gel based on lignin, characterized in that: The invention comprises the following components in parts by weight: 20 to 50 parts of a polymerizable monomer, 0.01 to 0.2 parts of a cross-linking agent, 0.01 to 0.15 parts of sodium lignin sulfonate, 3 to 6 parts of modified keratin, 0.1 to 1 parts of an initiator, 50 to 90 parts of a deep eutectic solvent, and 50 to 100 parts of water; the polymerizable monomer is acrylic acid and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide, and the modified keratin is a polyethylene glycol-based double-end cross-linking monomer and disulfide di(p-phenylene) bis(2-methacrylate) grafted modified keratin.

2. The lignin-based conductive eutectic gel according to claim 1, characterized in that The polyethylene glycol-based double-end cross-linking monomer is at least one of polyethylene glycol diacrylate or polyethylene glycol dimethacrylate, and the structural formula of the disulfide di(p-phenylene)di(2-methacrylate) is shown in Formula 1:

3. The lignin-based conductive eutectic gel according to claim 1, wherein The preparation of the modified keratin comprises the following steps: S1. Using feathers and hair as raw materials, urea as solvent, and L-cysteine as reducing agent, pure keratin was extracted by the swelling-reduction method. S2. Using tri(2-carbonylethyl)phosphine hydrochloride solution as a reducing agent, the disulfide bonds of keratin are reduced to thiol groups, and then polyethylene glycol-based double-end cross-linking monomers, disulfide di(p-phenylene)di(2-methylacrylate) and an initiator are added for graft modification to obtain modified keratin.

4. The lignin-based conductive eutectic gel according to claim 1, wherein The amount of the reducing solution added in step S2 is 80 wt% to 100 wt% of the keratin protein, and the amount of the polyethylene glycol-based double-end cross-linking monomer and disulfide di(p-phenylene)di(2-methacrylate) added is 60 wt% to 100 wt% of the keratin protein.

5. The lignin-based conductive eutectic gel according to claim 1, wherein The mass ratio of the acrylic acid and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide is (4-6):1, and the mass ratio of the polyethylene glycol-based double-end cross-linking monomer and disulfide di(p-phenylene)di(2-methacrylate) is (5-10):

1.

6. The lignin-based conductive eutectic gel according to claim 1, wherein The initiator is selected from at least one of potassium persulfate, ammonium persulfate, and sodium sulfite; the cross-linking agent is at least one of N,N'-methylenebisacrylamide, bisacrylamide, polyethylene glycol diacrylate, or polyethylene glycol dimethacrylate; and the deep eutectic solvent is an ethylene glycol solution of ZnCl2 with a molar ratio of 1:(5-8).

7. The method for preparing the lignin-based conductive eutectic gel according to claim 1, wherein: The method comprises the following steps: mixing a polymerizable monomer, a cross-linking agent, sodium lignin sulfonate, modified keratin, an initiator, a deep eutectic solvent and pure water to obtain a prepolymer solution; filling the prepolymer solution into a mold, vigorously stirring the mold with ultrasound, placing the mold in a vacuum drying oven, and heating the mold at 70-90°C for 30-60 minutes to obtain a lignin-based conductive eutectic gel.

8. Use of the lignin-based conductive eutectic gel according to any one of claims 1 to 7 in sensors, biomedicine and flexible electronics.

9. The use of the lignin-based conductive eutectic gel in sensors, biomedicine and flexible electronics according to claim 8, characterized in that: The conductive eutectic gel monitors human body movements through changes in electrical signal peak value and peak shape.

Images