Biomass-based eutectic gel as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of intelligent soft materials, and particularly relates to biomass-based eutectic gel as well as a preparation method and application thereof. The preparation method of the biomass-based eutectic gel comprises the following steps: adding demethylated lignin into a nanocellulose solution, adding a buffer solution, and mixing to obtain a suspension; mixing the suspension with a deep eutectic solvent, and heating to obtain a precursor solution; and adding a cross-linking agent and a photoinitiator into the precursor solution, and carrying out photopolymerization reaction to prepare the biomass-based eutectic gel. Related performance tests prove that the gel has the properties of strong adhesion, super-strong stretching and high sensing, and the prepared eutectic gel has better application potential in the directions of intelligent sensing and human body detection.

Description

Technical Field

[0001] The present invention belongs to the technical field of intelligent soft materials, and particularly relates to a biomass-based eutectic gel and its preparation method and application. Background Art

[0002] With the increasing demand for renewable energy and the gradual depletion of traditional fossil fuel energy, as well as the resulting environmental problems, it has become crucial to develop efficient and environmentally friendly sensing systems. In the field of sensing, with the development of the Internet of Things, intelligent wearable devices, and environmental monitoring systems, the demand for high-performance sensors is increasing day by day. Although traditional gel materials have been applied in some types of sensors, they have a series of limitations, such as insufficient mechanical strength, sensitivity to temperature and humidity, long response time, and unstable performance under specific environmental conditions. These problems limit their wide application in high-performance sensing devices.

[0003] Eutectic gel is a gel system based on deep eutectic solvents. As a new type of material, it inherits the advantages of deep eutectic solvents, such as good cost-effectiveness, environmental friendliness, stability at room temperature, air stability, and biodegradability. In addition, eutectic gels overcome the problem of easy spillage of deep eutectic solvents and exhibit the characteristic of high plasticity, which enables them to adapt to the requirements of complex shapes and expands the application range of ionic liquids.

[0004] Lignin is the second most abundant natural polymer material in the plant kingdom after cellulose. Lignin contains abundant functional groups such as alcoholic hydroxyl groups, phenolic hydroxyl groups, and methoxy groups. Introducing lignin into the gel can endow the gel with good mechanical properties, biocompatibility, adhesiveness, and ultraviolet shielding properties. However, due to the complexity of its own structure and poor water solubility, it is difficult to be fully utilized.

[0005] In the prior art, lignin is often modified to form alkali lignin, sodium lignosulfonate, or made into nano-lignin fibers and then introduced into the gel. However, the prepared eutectic gels have poor mechanical property stability, weak adhesiveness, freezing at extreme temperatures, etc., which are difficult to meet the actual application requirements and cannot be used as a resistive sensing module to construct wearable sensors, and have poor sensing performance in interference tests (twisting and puncturing). Summary of the Invention

[0006] The purpose of the present invention is to provide a biomass-based eutectic gel and its preparation method and application, so as to overcome the deficiencies of the prior art, and to apply a conductive eutectic gel with strong adhesion, super stretchability, and high sensing sensitivity as a conductor in a sensor.

[0007] To achieve the above purpose, the technical solution of the present invention is as follows:

[0008] In a first aspect, the present invention provides a method for preparing a biomass-based eutectic gel, comprising the following steps:

[0009] Add demethylated lignin to the nanocellulose solution, and add a buffer solution and mix to obtain a suspension;

[0010] Mix the suspension with a deep eutectic solvent and heat to obtain a precursor solution;

[0011] Add a crosslinking agent and a photoinitiator to the precursor solution, and carry out a photopolymerization reaction to obtain a biomass-based eutectic gel.

[0012] In some other embodiments, the method for preparing the demethylated lignin is: mix LiBr and water, and successively add lignin and HBr and carry out a reflux reaction to obtain demethylated lignin.

[0013] In some other embodiments, the ratio of LiBr, water, lignin, and HBr is (55 - 65) g : (35 - 45) g : (3 - 8) g : (5 - 25) mL;

[0014] The temperature of the reflux reaction is 80 - 120 °C, and the time is 3 - 5 hours;

[0015] After the reflux reaction, a purification treatment is also carried out. The purification treatment is to successively cool and filter, wash to neutrality, and freeze-dry the product after the reflux reaction.

[0016] In some other embodiments, the mass ratio of the demethylated lignin to the nanocellulose solution is (100 - 300) mg : (5 - 10) g;

[0017] The concentration of the nanocellulose solution is 1 wt% - 5 wt%;

[0018] The buffer solution is a tris(hydroxymethyl)aminomethane buffer solution;

[0019] The temperature of the mixing is room temperature, and the time is 4 - 12 h;

[0020] The pH of the suspension is 8 - 8.5;

[0021] In some other embodiments, the deep eutectic solvent is formed by mixing a hydrogen bond donor compound and a hydrogen bond acceptor compound;

[0022] The hydrogen bond donor compound is selected from one or more of formamide, acetamide, urea, ethylene glycol, glycerol, N-methylacetamide, oxalic acid, maleic acid, acrylic acid, methacrylic acid, acrylamide, monoethanolamine, citric acid, and sorbitol;

[0023] The hydrogen bond acceptor compound is selected from one or more of halogen-containing ammonium salts, halogen-containing quaternary ammonium salts, halogen-containing phosphonium salts, and metal halides;

[0024] Preferably, the hydrogen bond donor compound is one of acrylic acid, ethylene glycol, and acrylamide;

[0025] The hydrogen bond acceptor compound is one of choline chloride, zinc chloride, and tris(2-chloroethyl) phosphate;

[0026] More preferably, the hydrogen bond donor compound is acrylic acid, and the hydrogen bond acceptor compound is choline chloride; the molar ratio of the acrylic acid to the choline chloride in the mixture is (0.5 - 10):1.

[0027] More preferably, the molar ratio of the acrylic acid to the choline chloride in the mixture is (0.5 - 10):1.

[0028] In some other embodiments, the mass ratio of the suspension to the deep eutectic solvent is 1:(10 - 20);

[0029] The heating temperature is 60 - 150 °C, and the time is 1 - 3 h.

[0030] In some other embodiments, the cross-linking agent is one or more of N,N'-methylenebisacrylamide, polyethylene glycol diacrylate, glycerol triacrylate, and pentaerythritol tetraacrylate;

[0031] The photoinitiator is one or more of benzoin methyl ether, benzoin dimethyl ether, 2,2-dimethoxy-2-phenylacetophenone, triarylsulfonium hexafluorophosphate, ammonium persulfate, benzoin ether, and 2,4,6-trimethylbenzoyl diphenylphosphine oxide;

[0032] The addition amount of the cross-linking agent is 5 - 40 mg; the addition amount of the photoinitiator is 20 - 60 mg.

[0033] In some other embodiments, the photopolymerization reaction is carried out at room temperature, irradiated with ultraviolet light of 365 nm with an intensity of 50 - 60 W for 1 - 3 min.

[0034] In a second aspect, the present invention provides the biomass-based eutectic gel prepared by the preparation method of the biomass-based eutectic gel described in the first aspect.

[0035] In a third aspect, the present invention provides the application of the biomass-based eutectic gel described in the second aspect in wearable devices, medical health monitoring devices, or human-computer interaction devices.

[0036] The beneficial effects of the present invention:

[0037] (1) The eutectic gel prepared by the present invention can be applied to human sensor devices. Compared with existing sensor devices, it has no liquid leakage problems, can stably exist in the air, has a stable vapor pressure and is not prone to water loss. The problems of self-corrosion, hydrogen evolution, and dendrite formation of the electrodes are significantly improved, thus enhancing the environmental adaptability. By using demethylated lignin and cellulose nanofibers as physical fillers to prepare the eutectic gel, it has excellent sensing performance, stability, strong tensile strength, strong adhesion performance, a wide detection range, and the sensor still maintains excellent stability after multiple cycles.

[0038] (2) The method provided by the present invention does not require complex treatment of biological raw materials. It is prepared by a one-pot method, with simple operation. Different performance eutectic gel structures can be obtained only by adjusting the ratio of lignin and cellulose nanofibers. It has high efficiency and low cost, and has great potential in the fields of harsh environment detection at high and low temperatures, human health monitoring, and motion detection.

[0039] (3) The eutectic gel prepared by the present invention also has the characteristic that its conductivity changes with external force and can be used as a mechanical sensor.

[0040] (4) The biomass components selected in the present invention have a good strengthening effect when added to the DES. Description of the Drawings

[0041] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0042] Figure 1 is the process flow chart for the preparation of the eutectic gel;

[0043] Figure 2 is the infrared spectrum of the eutectic gels prepared in Examples 1 - 3;

[0044] Figure 3 is the fracture tensile curve of the eutectic gels prepared in Comparative Example 1 and Examples 1 - 3;

[0045] Figure 4 is the adhesion strength of the eutectic gels prepared in Examples 1 - 3 to different substrates;

[0046] Figure 5 is the fracture tensile curve of the eutectic gel prepared in Example 3 at different temperatures;

[0047] Figure 6 is the strain sensing sensitivity curve of the eutectic gel prepared in Example 3 to different materials;

[0048] Figure 7 is the low strain sensing response time of the eutectic gel prepared in Example 3. Detailed implementation manners

[0049] Those skilled in the art will understand that the following embodiments are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. Specific conditions are not indicated in the embodiments and are carried out according to conventional conditions or conditions recommended by the manufacturer. Components not indicated by the manufacturer are all conventional products available commercially.

[0050] Preparation of eutectic gel

[0051] Example 1

[0052] A biomass-based eutectic gel is prepared by ultraviolet cross-linking method. The specific experimental process is as Figure 1 shown and includes the following steps:

[0053] Step 1): Demethylation of lignin

[0054] LiBr (61 g) and water (39 g) are added into a round-bottom glass flask equipped with a polytetrafluoroethylene stirring rod and a reflux condenser. Stir for 5 minutes until LiBr is completely dissolved. Then alkali lignin (5 g) is added, and then 10 mL of HBr is added to obtain a mixture; the mixture is heated to the reaction temperature of 100 °C in an oil bath and refluxed for 4 hours. After the reaction is completed, the mixture is cooled in a water bath and filtered on a glass Buchner funnel. The collected demethylated lignin is washed with deionized water until the filtrate is neutral (pH = 7), and then freeze-dried to obtain demethylated lignin.

[0055] Step 2): Preparation of demethylated lignin cellulose nanofiber suspension

[0056] 50 mg of demethylated lignin is dissolved in 6 g of cellulose nanofiber (CNF) suspension (2.15 wt%) until completely dissolved to obtain a mixture; then, 2 mL of tris(hydroxymethyl)aminomethane buffer solution is added to the mixture to adjust the pH value to 8.0, and stirred at room temperature for 12 hours to obtain a CNF suspension coated with demethylated lignin.

[0057] Step 3): Preparation of eutectic gel

[0058] First, 2 g of demethylated lignin-coated CNF suspension was mixed with 10.66 g of acrylic acid (AA) and 10.33 g of choline chloride (ChCl) to obtain a mixture. Then, the mixture was heated at 90 °C for 2 hours to obtain a transparent reddish-brown precursor solution. After cooling to room temperature, 5 mg of N,N'-methylenebisacrylamide (MBA) and 40 mg of 2,4,6-trimethylbenzoyl diphenylphosphine oxide (TPO) were added to the above precursor solution with respect to acrylic acid (AA), and continuously stirred until completely dissolved. Then, it was poured into a polytetrafluoroethylene mold and irradiated with 365-nm ultraviolet light at a strength of 60 W for 2 minutes at room temperature for photopolymerization reaction to obtain the eutectic gel.

[0059] Example 2:

[0060] The biomass-based eutectic gel was prepared by ultraviolet cross-linking method. Different from Example 1, in the preparation method of demethylated lignin cellulose nanofiber suspension in step 2), 100 mg of demethylated lignin was dissolved in 6 g of CNF suspension (2.15 wt%) until completely dissolved, and other preparation steps were the same as those in Example 1.

[0061] Example 3

[0062] The biomass-based eutectic gel was prepared by ultraviolet cross-linking method. Different from Example 1, in step 2): in the preparation method of demethylated lignin cellulose nanofiber suspension, 150 mg of demethylated lignin was dissolved in 6 g of CNF suspension (2.15 wt%) until completely dissolved, and other preparation steps were the same as those in Example 1.

[0063] Example 4

[0064] Different from Example 1, in the preparation method of demethylated lignin cellulose nanofiber suspension in step 2), 300 mg of demethylated lignin was dissolved in 6 g of CNF suspension (2.15 wt%) until completely dissolved, and other preparation steps were the same as those in Example 1.

[0065] Comparative Example 1

[0066] 10.66 g of acrylic acid (AA) and 10.33 g of choline chloride (ChCl) were mixed and heated at 90 °C for 2 hours to obtain a transparent precursor solution. After cooling to room temperature, 5 mg of N,N'-methylenebisacrylamide (MBA) and 40 mg of 2,4,6-trimethylbenzoyl diphenylphosphine oxide (TPO) were added to the precursor solution, and continuously stirred until completely dissolved. Then, it was poured into a polytetrafluoroethylene mold and irradiated with 365-nm ultraviolet light at a strength of 60 W for 1 minute at room temperature for photopolymerization reaction to obtain the eutectic gel.

[0067] Comparative Example 2

[0068] 10.66 g of acrylic acid (AA) and 10.33 g of choline chloride (ChCl) were mixed and heated at 90 °C for 2 h to obtain a transparent precursor solution. After cooling to room temperature, 150 mg of demethylated lignin was dissolved in 6 g of an aqueous solution of cellulose nanocrystals (2.15 wt%), until completely dissolved. Then, 2 g of an aqueous solution of cellulose nanocrystals (CNC), 5 mg of N,N'-methylenebisacrylamide (MBA), and 40 mg of 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO) were added to the precursor solution and stirred continuously until completely dissolved. Then, it was poured into a polytetrafluoroethylene mold and irradiated with 365-nm ultraviolet light at a strength of 60 W for 0 - 1 min at room temperature for photopolymerization reaction to obtain a eutectic gel.

[0069] Comparative Example 3

[0070] 10.66 g of acrylic acid (AA) and 10.33 g of choline chloride (ChCl) were mixed and heated at 90 °C for 2 h to obtain a transparent precursor solution. After cooling to room temperature, 150 mg of sodium lignosulfonate was dissolved in 6 g of cellulose nanofibers (CNF) (2.15 wt%), until completely dissolved. Then, 2 g of a cellulose nanofiber solution, 5 mg of N,N'-methylenebisacrylamide (MBA), and 40 mg of 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO) were added to the precursor solution and stirred continuously until completely dissolved. Then, it was poured into a polytetrafluoroethylene mold and irradiated with 365-nm ultraviolet light at a strength of 60 W for 1 min at room temperature for photopolymerization reaction to obtain a eutectic gel.

[0071] Performance Test

[0072] 1. Fourier transform infrared spectroscopy (FT-IR) test

[0073] The eutectic gel was characterized using a Fourier transform infrared spectrometer, with a wavenumber range of 800 - 4000 cm -1 , and a resolution of 4 cm -1 . The Fourier transform infrared spectroscopy test results of the eutectic gels prepared in Examples 1 - 3 are as Figure 2 shown.

[0074] As can be seen from Figure 2 , in Examples 1 - 3, the absorption peak at 1721 - 1723 cm -1 is the stretching vibration of -C=O on the acrylic acid (AA) eutectic gel; at 3431 - 3481 cm -1The absorption peaks at [the specified position] are the stretching vibration peaks of OH on the eutectic gel, and the peak positions are shifted, indicating that intermolecular hydrogen bonds are formed between ChCl and AA in the DES, that is, solid ChCl becomes liquid DES after mixing with AA. As the lignin content increases, the 3431 cm -1 The red shift of the hydroxyl absorption peak at [the specified position] is attributed to the close arrangement of hydrogen bonds.

[0075] 2. Tensile fracture properties

[0076] The tensile fracture properties of the eutectic gel were detected using a universal tensile machine: the two ends of the eutectic gel were regularly clamped on the tensile machine, the tensile speed was set to 100 mm / min, and the stress-strain data during this process were recorded in real time until the eutectic gel in the tensile machine broke from the middle. The tensile fracture properties of the eutectic gels prepared in Comparative Example 1 and Examples 1-3 are as Figure 3 shown.

[0077] From Figure 3 it can be seen that the tensile strength of the eutectic gel prepared in Comparative Example 1 is 67.1 kPa, and the elongation at break is 1861%; the tensile strength of the eutectic gel prepared in Example 1 is 132.6 kPa, and the elongation at break is 3957%; the tensile strength of the eutectic gel prepared in Example 2 is 271.77 kPa, and the elongation at break is 4336%; the tensile strength of the eutectic gel prepared in Example 3 is 221.4 kPa, and the elongation at break is 5001%. It is proved that the eutectic gel prepared by adding 150 mg of demethylated lignin in Example 3 has the best elongation at break, and the mechanical properties are enhanced with the gradual addition of demethylated lignin.

[0078] 3. Adhesion property test

[0079] The tensile fracture properties of the obtained eutectic gel were detected using a universal tensile machine. Five different substrates were selected, including: glass, copper sheet, wood, plastic, pigskin, rubber. The substrates were cut into a size of 70 mm * 30 mm, and then the eutectic gel was placed flat against the wide edge, laid flat on the cut substrates lengthwise and widthwise, and then another substrate was covered on the other side of the gel to avoid air bubbles in the pasting area. Then the two ends of the pasted substrates were clamped on the tensile machine, the tensile speed was set to 100 mm / min, and the adhesion curve during this process was recorded in real time until the two substrates separated. Each substrate was measured in parallel three times. The test results of the adhesion strength of the eutectic gels prepared in Examples 1-3 for different substrates are as Figure 4 shown.

[0080] From Figure 4It can be seen that the adhesion strength of Example 1 can reach 60 kPa, that of Example 2 can reach 70 kPa, and that of Example 3 can reach 111 kPa. With the increase of demethylated lignin, the adhesion force of the eutectic gel gradually increases to 111 kPa. The adhesion strength between the eutectic gel and different substrates all increases significantly. Example 3 maintains strong adhesion in a variety of substrates. The adhesion forces to copper, paper, wood, glass, rubber and pigskin are 111, 108, 87, 79, 82 and 67 kPa respectively. The adhesion strength of Example 3 to pigskin at 67 kPa is 2.4 times that of 28 kPa in Example 1, and the adhesion force on the copper sheet is the strongest at 111 kPa. The significant improvement in adhesion strength is attributed to the abundant catechol groups provided with the increase in the amount of lignin, which form dynamic interactions with the polar groups on the substrate and also help to enhance the energy dissipation generated by dense dynamic hydrogen bonds.

[0081] 4. Temperature adaptability test

[0082] Use a universal tensile machine to detect the fracture tensile properties of the eutectic gel at different temperatures. Clamp both ends of the eutectic gel neatly on the tensile machine, set the tensile speed to 100 mm / min, and record the stress-strain data in real time during this process until the eutectic gel in the tensile machine breaks from the middle.

[0083] To verify the adaptability of the eutectic gel at various temperatures, we conducted a heat resistance experiment, and the test temperatures were -80 °C, -20 °C, 0 °C, 25 °C and 60 °C respectively. From Figure 5 It can be seen that this material exhibits excellent multi-temperature adaptability, can be used in a wide range of environments, and greatly expands its application scope. With the change of temperature, the stress of the material always remains within a stable range, ensuring stable signal output in various situations. In addition, within the detected temperature range, Example 3 shows stable stress, changing from 221.4 kPa at room temperature to 231.3 kPa and 255.3 kPa at ultra-low temperature -80 °C and ultra-high temperature 60 °C respectively, as well as different deformation amounts, which actually reflects its thermal expansion or contraction behavior under different temperature conditions, but the strain of the material still has strong advantages. This property not only demonstrates the stability and reliability of the material in extreme environments, but also further confirms its wide applicability.

[0084] 5. Strain sensing sensitivity test

[0085] The strain sensing performance of the prepared eutectic gel sensor was detected by using a universal tensile testing machine and a digital source meter in combination. A 5-mm-wide conductive copper sheet was regularly pasted around both ends of the eutectic gel, and then it was clamped on the tensile testing machine together with the wound conductive copper sheet. At the same time, the conductive copper sheet was extended, and then the sensor was connected to the digital source meter through the conductive copper sheet. Then, the sensor was stretched / released with different strains by the tensile testing machine, and the resistance change signal of the sensor during this process was recorded in real time. The strain sensing sensitivity curves of the eutectic gel prepared in Example 3 for different materials are as Figure 6 shown.

[0086] As can be seen from Figure 6 , the sensing sensitivities of the eutectic gel prepared in Example 3 in different regions reached 1.57 (0 - 200%), 1.94 (200 - 375%), and 2.51 (375 - 550%) respectively, proving the high sensitivity and wide sensing range of the eutectic gel sensor, and it can realize the monitoring of the change of human body's electrical signals.

[0087] Figure 7 This is the low-strain sensing reaction time of the eutectic gel prepared in Example 3. As can be seen from Figure 7 , the eutectic gel strain sensor prepared in Example 3 showed a fast reaction speed. The relative change time of its resistance was about 96.7 milliseconds, and the recovery time was about 77.5 milliseconds. This performance is comparable to the natural response time (50 - 100 ms) of human skin, highlighting the potential application advantages of this material in the field of bionic sensing. The performances of the examples and comparative examples of the present invention are shown in Table 1.

[0088] Table 1 Performances of Examples and Comparative Examples

[0089]

[0090]

[0091] As can be seen from Table 1, from Comparative Example 1 and Example 3, it can be seen that the addition of cellulose nanofibers and demethylated lignin has a very obvious improvement on the acrylic-based eutectic gel. The strain is increased by 166%, the stress is increased by 266%, and the adhesion performance is increased by 120%. This is due to the rich hydrogen bond network between the catechol groups in demethylated lignin and acrylic acid. From Comparative Examples 1, 2, and 3, it can be seen that biomass raw materials and their derivatives are all beneficial to improving the overall performance of the material, but the long-chain fibers of nanocellulose and the demethylation of lignin are more beneficial to the improvement of mechanical properties. From Examples 3, 5, and 6, it can be seen that the biological filler has universality for various gels.

[0092] In summary, the method of the present invention for preparing a eutectic gel from cellulose nanofibers and demethylated lignin is based on a gel system formed by a deep eutectic solvent, inheriting the advantages of the deep eutectic solvent, such as good cost-effectiveness, environmental friendliness, stability at room temperature, and biodegradability. The eutectic gel has advantages such as a wide detection range, high sensitivity, and short reaction time. Using the eutectic gel as a resistive sensing module to construct a wearable sensor provides stable sensing performance under interference tests (torsion and puncture).

[0093] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a biomass-based eutectic gel, characterized in that: The following steps are involved: adding demethylated lignin to the nanocellulose solution, adding a buffer solution and mixing to obtain a suspension; The suspension is mixed with a deep eutectic solvent and heated to obtain a precursor solution; A cross-linking agent and a photoinitiator are added to the precursor solution to carry out a photopolymerization reaction to prepare a biomass-based eutectic gel.

2. The method for preparing the biomass-based eutectic gel according to claim 1, characterized in that: The preparation method of the demethylated lignin comprises: mixing LiBr and water, and sequentially adding lignin and HBr to perform reflux reaction to obtain the demethylated lignin.

3. The method for preparing the biomass-based eutectic gel according to claim 2, characterized in that: The ratio of LiBr, water, lignin and HBr is (55-65) g: (35-45) g: (3-8) g: (5-25) mL; The reflux reaction temperature is 80-120°C and the time is 3-5 hours; After the reflux reaction, a purification treatment is further performed, wherein the product after the reflux reaction is sequentially cooled and filtered, washed to neutrality, and freeze-dried.

4. The method for preparing the biomass-based eutectic gel according to claim 1, characterized in that: The mixing mass ratio of the demethylated lignin and the nanocellulose solution is (100-300) mg: (5-10) g; The concentration of the nanocellulose solution is 1wt%-5wt%; The buffer solution is a tris(hydroxymethyl)aminomethane buffer solution; The mixing temperature is room temperature and the mixing time is 4-12h; The pH of the suspension is 8-8.

5.

5. The method for preparing the biomass-based eutectic gel according to claim 1, characterized in that: The deep eutectic solvent is formed by mixing a hydrogen bond donor compound and a hydrogen bond acceptor compound; The molar ratio of the hydrogen bond donor compound and the hydrogen bond acceptor compound is (0.5-10):1; The hydrogen bond donor compound is selected from one or more of formamide, acetamide, urea, ethylene glycol, glycerol, N-methylacetamide, oxalic acid, maleic acid, acrylic acid, methacrylic acid, acrylamide, monoethanolamine, citric acid and sorbitol; The hydrogen bond acceptor compound is selected from one or more of halogen-containing ammonium salts, halogen-containing quaternary ammonium salts, halogen-containing phosphonium salt compounds and metal halides; Preferably, the hydrogen bond donor compound is one of acrylic acid, ethylene glycol and acrylamide; The hydrogen bond acceptor compound is one of choline chloride, zinc chloride and trichloroethyl phosphate; Further preferably, the hydrogen bond donor compound is acrylic acid, and the hydrogen bond acceptor compound is choline chloride; the molar ratio of the acrylic acid to the choline chloride is (0.5-10):

1.

6. The method for preparing the biomass-based eutectic gel according to claim 1, characterized in that: The suspension and the deep eutectic solvent are mixed in a mass ratio of 1:(10-20); The heating temperature is 60-150° C. and the heating time is 1-3 hours.

7. The method for preparing the biomass-based eutectic gel according to claim 1, characterized in that: The cross-linking agent is one or more of N,N'-methylenebisacrylamide, polyethylene glycol diacrylate, glycerol triacrylate and pentaerythritol tetraacrylate; The photoinitiator is one or more of benzoin methyl ether, benzoin dimethyl ether, 2,2-dimethoxy-2-phenylacetophenone, triarylsulfonium hexafluorophosphate, ammonium persulfate, benzoin ether and 2,4,6-trimethylbenzoyldiphenylphosphine oxide; The added amount of the cross-linking agent is 5-40 mg; the added amount of the photoinitiator is 20-60 mg.

8. The method for preparing the biomass-based eutectic gel according to claim 1, characterized in that: The photopolymerization reaction is carried out at room temperature using 365 nm ultraviolet rays with an intensity of 50-60 W for 1-3 minutes.

9. A biomass-based eutectic gel obtained by the method for preparing a biomass-based eutectic gel according to any one of claims 1 to 8.

10. Use of the biomass-based eutectic gel according to claim 9 in wearable devices, medical health monitoring devices or human-computer interaction devices.

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