Method for preparing conductive hydrogel by using deep eutectic solvent to develop waste biomass and application of conductive hydrogel

Abstract

The invention belongs to the technical field of hydrogel, and particularly relates to a method for preparing conductive hydrogel by developing waste biomass through a deep eutectic solvent and application of the conductive hydrogel. According to the method for preparing the conductive hydrogel by developing the waste biomass through the deep eutectic solvents, the deep eutectic solvents such as urea / ethylene glycol, choline chloride / lactic acid and the like are prepared firstly, and then high-price resources are extracted from poultry feathers and plant biomass for heavy metal pollution remediation through the deep eutectic solvents; the conductive hydrogel is prepared from the modified starch, an auxiliary gelling polymer and a cross-linking agent aqueous solution, so that the conductive hydrogel can be endowed with excellent anti-freezing property, mechanical property and conductivity; therefore, the technical problem that high-performance conductive hydrogel is difficult to prepare by an existing preparation process is solved.

Description

Technical Field

[0001] The present application belongs to the field of hydrogel technology, and in particular relates to a method and application of using deep eutectic solvents to develop waste biomass to prepare conductive hydrogels. Background Art

[0002] Conductive hydrogel is a type of functional material with a hydrophilic polymer skeleton and conductive components with a three-dimensional network structure. Conductive hydrogel has a wide range of applications in the fields of flexible electronics, biomedicine, and energy storage. For example, it can be made into electronic skin to simulate the tactile perception function of human skin and achieve tactile feedback for use in robotic prostheses. It can also be made into flexible sensors for monitoring joint movement and for wearable health monitoring equipment. It can also be made into implantable electrodes as medical devices for detecting physiological signals, or as a drug delivery medium for drug release triggered by electrical signals. It can also be used as electrode materials and electrolyte materials for energy storage devices such as supercapacitors. Conductive hydrogel has shown great application potential in many fields.

[0003] However, the high water content of traditional conductive hydrogels (usually over 90%) makes them easy to freeze in low-temperature environments, forming ice crystals, thereby reducing elasticity, flexibility and ionic conductivity, severely limiting their practical application in low-temperature conditions and cold areas (such as the polar regions and outdoors in winter); at the same time, the hydrophilic polymer skeleton and doped conductive polymers, metal nanomaterials, MXene and other conductive components in the conductive hydrogel have weak interface bonding problems and poor stability. After long-term use, the conductive hydrogel is prone to structural damage, and conductive ionic liquids, such as fluorine-containing and imidazole-containing conductive ionic liquids, have toxicity and corrosive problems, which may cause skin irritation or cytotoxicity. They are not suitable as conductive components for use in conductive hydrogels with higher biocompatibility. At the same time, the preparation process of conductive ionic liquids is complex and the cost is high.

[0004] At present, the development and utilization of biomass resources is relatively low. For example, chicken feathers in poultry are short in fiber and difficult to process, so most of them are landfilled or incinerated, causing resource waste and environmental pollution. However, the feather keratin in poultry feathers has excellent mechanical properties (Young's modulus 1-10 GPa, tensile strength 60-250 MPa), if a process can be developed to effectively extract feather keratin from poultry feathers and use it as the hydrophilic polymer skeleton of conductive hydrogel, the structural stability of the conductive hydrogel can be improved; in addition, the soil in some mining areas is contaminated with heavy metals. By planting plants with high tolerance and enrichment capacity for heavy metals, such as Sedum, Phytolacca, and Cyperus rotundus, they can be used to remediate soil contaminated by heavy metals such as zinc, cadmium, and manganese. However, for the large amount of heavy metal-rich plant biomass produced by planting, the traditional treatment method is direct landfilling and pyrolysis of Sedum and other biomass, which has high energy consumption and secondary pollution risks. If a process can be developed to effectively extract heavy metals from Sedum and other biomass and use it as the conductive component of conductive hydrogel, heavy metal-contaminated plants can be transformed from an environmental burden to a high-value material; therefore, focusing on the optimization of low-temperature performance of hydrogels, improvement of conductivity, heavy metal pollution control and resource utilization of biomass, developing a new conductive hydrogel preparation process to prepare high-performance conductive hydrogels is a technical problem that needs to be solved urgently. Summary of the Invention

[0005] In view of this, the present application provides a method and application of using deep eutectic solvents to develop waste biomass to prepare conductive hydrogels, which is used to solve the technical problem that existing preparation processes are difficult to prepare high-performance conductive hydrogels.

[0006] In a first aspect of the present application, a method for preparing a conductive hydrogel from waste biomass using a deep eutectic solvent is provided. The preparation method comprises the following steps:

[0007] The steps for preparing a deep eutectic solvent are as follows: a hydrogen bond acceptor and a hydrogen bond donor are mixed and then heated to obtain a deep eutectic solvent;

[0008] The poultry feather processing steps include: crushing the poultry feathers into feather powder, mixing with a deep eutectic solvent, heating and stirring, and centrifuging to obtain a feather keratin solution;

[0009] The plant biomass processing steps include: crushing the plant biomass containing heavy metals into plant biomass powder, mixing with a deep eutectic solvent, heating and stirring, and centrifuging to obtain a plant biomass extract solution;

[0010] The conductive hydrogel cross-linking molding step is as follows: mixing and heating a hydroxyl-containing auxiliary gel-forming polymer, a cross-linking agent, an aqueous solution, a feather keratin solution and a plant biomass extract solution, and then placing the mixture in a mold and cooling it to room temperature to obtain a conductive hydrogel.

[0011] Preferably, in the step of configuring the deep eutectic solvent, the hydrogen bond acceptor used is selected from at least one of choline chloride, urea, and betaine, and the hydrogen bond donor used is selected from at least one of lactic acid, ethylene glycol, glycerol, tartaric acid, oxalic acid, and malic acid.

[0012] Preferably, in the poultry feather processing step, the poultry feathers used are selected from at least one of chicken feathers, duck feathers and goose feathers.

[0013] Preferably, in the plant biomass processing step, the heavy metal-containing plant biomass used is at least one selected from Sedum multiflorum, Phytolacca americana, and Cyperus rotundus.

[0014] Preferably, in the step of cross-linking the conductive hydrogel, the hydroxyl-containing auxiliary gel-forming polymer used is selected from at least one of polyvinyl alcohol, polyacrylic acid, hyaluronic acid, and chitosan, and the cross-linking agent used is selected from at least one of citric acid, tartaric acid, oxalic acid, and malic acid.

[0015] Preferably, in the poultry feather processing step, the mass ratio of chicken feather powder to deep eutectic solvent is 0.2-2:10, the heating and stirring temperature is 90-150° C., and the time is 1-5 hours.

[0016] Preferably, in the plant biomass processing step, the mass ratio of chicken feather powder to deep eutectic solvent is 0.5-3:10, the heating and stirring temperature is 100-150° C., and the time is 3-10 hours.

[0017] Preferably, the steps of cross-linking and forming the conductive hydrogel specifically include:

[0018] Step S1, dissolving a crosslinking agent in an aqueous solution at 80-100° C., then adding a hydroxyl-containing auxiliary gel-forming polymer, mixing and heating for 5-15 minutes to obtain a polymer solution;

[0019] Step S2: mixing the feather keratin solution, the plant biomass extract solution, and the polymer solution and heating them at 100-150° C. for 5-15 minutes to obtain a conductive hydrogel precursor solution;

[0020] Step S3: placing the conductive hydrogel precursor solution in a mold and cooling it to room temperature to obtain a conductive hydrogel precursor.

[0021] Preferably, calculated in parts by mass, the conductive hydrogel precursor solution includes: 10 to 15 parts by mass of a hydroxyl-containing auxiliary gel-forming polymer, 10 to 15 parts by mass of a cross-linking agent, 20 to 40 parts by mass of an aqueous solution, 20 to 40 parts by mass of a feather keratin solution, and 1 to 40 parts by mass of a plant biomass extract solution.

[0022] The second aspect of the present application provides a method for preparing conductive hydrogels from waste biomass using a deep eutectic solvent as described in the first aspect, and the conductive hydrogels obtained are used in the fields of flexible electronics, biomedicine or energy storage.

[0023] Compared with the prior art, the method provided in this application for preparing conductive hydrogels from waste biomass using deep eutectic solvents has at least the following beneficial effects:

[0024] 1. The method provided in this application for preparing conductive hydrogels from waste biomass using deep eutectic solvents focuses on optimizing the low-temperature performance of hydrogels, improving conductivity, controlling heavy metal pollution, and utilizing biomass resources. A new technical route for preparing high-performance conductive hydrogels from waste biomass based on deep eutectic solvents has been developed.

[0025] 2. This application provides a method for preparing conductive hydrogels from waste biomass using deep eutectic solvents, further exploring the performance of conductive hydrogels under different mass proportions of feather keratin solution and Sedum extract solution, and developing conductive hydrogel functional materials with both excellent mechanical properties and conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 The antifreeze performance test results of the conductive hydrogels provided in Example 1 and Comparative Example 1 of the present application;

[0028] Figure 2 The mechanical properties test results of the conductive hydrogels containing different weight percentages of feather keratin solutions provided in Examples 1-9 of the present application;

[0029] Figure 3 These are the test results of the conductive properties of the conductive hydrogels containing different mass proportions of the Sedum extract solutions provided in Examples 1-14 of the present application. DETAILED DESCRIPTION

[0030] The present application provides a method and application for preparing conductive hydrogels from waste biomass using deep eutectic solvents, which is used to solve the technical problem that existing preparation processes are difficult to prepare high-performance conductive hydrogels.

[0031] The following will clearly and completely describe the technical solution of this application in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0032] In view of the current lack of low-temperature performance optimization, conductivity improvement, heavy metal pollution control and biomass resource utilization of hydrogels, a new conductive hydrogel preparation process has been developed; this patent application provides a method for developing waste biomass to prepare conductive hydrogels using deep eutectic solvents, the method comprising first mixing a hydrogen bond acceptor and a hydrogen bond donor and then heating to form a homogeneous liquid to obtain a deep eutectic solvent; then using the deep eutectic solvent and poultry feather powder to mix, heat and stir, and centrifuge to obtain a feather keratin solution, or using the deep eutectic solvent and heavy metal-containing plant biomass powder to mix, heat and stir, and centrifuge to obtain a plant biomass extract solution; next, mixing and heating a hydroxyl-containing auxiliary gel-forming polymer, a crosslinker aqueous solution, a feather keratin solution and a plant biomass extract solution, and then placing it in a mold and cooling it to room temperature to obtain a conductive hydrogel.

[0033] In addition to some antifreeze agents, the freezing point can also be lowered by weakening the hydrogen bonding between water molecules. In the method for preparing conductive hydrogel provided by this patent application, the added deep eutectic solvent DES can effectively inhibit the formation of ice crystals through the hydrogen bond reconstruction at the molecular level, and the antifreeze performance can reach -115°C, so that the conductive hydrogel can still maintain excellent flexibility and conductivity under extreme cold conditions, thereby achieving the optimization of the low-temperature performance of the conductive hydrogel; on the other hand, the added deep eutectic solvent DES has thermal stability and chemical stability similar to ionic liquids, and can also be used through anions and cations (such as cations of choline salts, carboxylates / chlorides, etc.) ions) can realize charge transfer, have conductivity, and achieve improved conductivity; on the other hand, this patent application also uses the deep eutectic solvent DES to extract feather keratin, heavy metals and other extracts from poultry feathers and heavy metal-containing plant biomass, realizing high-value resource utilization of waste biomass and avoiding secondary environmental pollution that may be caused by heavy metal-contaminated plants; it can be seen that the present application constructs a preparation process for conductive hydrogel based on the deep eutectic solvent DES, and the prepared conductive hydrogel has excellent antifreeze, conductivity and mechanical properties, and is a high-performance conductive hydrogel, which overcomes the current defect that it is difficult to prepare high-performance conductive hydrogels.

[0034] As a preferred technical solution, this patent application further studies the effects of different mass proportions of feather keratin solution and sedum extract solution in the conductive hydrogel on its mechanical properties and conductive properties, achieves comprehensive regulation of mechanical properties and conductive properties, and obtains a conductive hydrogel with both excellent mechanical properties and conductivity. It has advantages in preparation process, cost control and environmental friendliness, and is a conductive hydrogel that is expected to be industrially produced and put into practical application.

[0035] The method for preparing conductive hydrogel by developing waste biomass using deep eutectic solvents provided in this application will be specifically described below with reference to examples, comparative examples and experimental examples.

[0036] Example 1

[0037] This embodiment 1 provides a method for preparing a conductive hydrogel from waste biomass using a deep eutectic solvent, including a step of preparing a deep eutectic solvent, a step of processing chicken feathers, a step of processing Sedum, and a step of cross-linking and forming the conductive hydrogel.

[0038] The steps for preparing a deep eutectic solvent include:

[0039] The hydrogen bond acceptor urea and the hydrogen bond donor ethylene glycol were weighed in a molar ratio of 1:2, 0.5 mol of urea and 1 mol of ethylene glycol were respectively added to a reaction vessel, and the mixture was heated at 100°C for 30 minutes to form a homogeneous liquid, thereby obtaining a first deep eutectic solvent; the hydrogen bond acceptor choline chloride and the hydrogen bond donor lactic acid were weighed in a molar ratio of 1:10, 0.1 mol of choline chloride and 1 mol of lactic acid were respectively added to a reaction vessel, and the mixture was heated at 100°C for 30 minutes to form a homogeneous liquid, thereby obtaining a second deep eutectic solvent.

[0040] The chicken feather processing steps include: first, cutting the chicken feathers collected from the market into small pieces with a tool, placing them in a grinder and crushing them three times, each time for 3 minutes, to obtain uniform chicken feather powder; then, adding 2.5g of the chicken feather powder and 50g of the first deep eutectic solvent into a container, heating it to 120°C and stirring it for 3 hours to extract feather keratin from the chicken feathers, and then centrifuging to obtain the supernatant, which is the feather keratin solution.

[0041] The processing steps of Sedum include: first, cutting Sedum plants collected near the mining area into small pieces with tools, placing them in a grinder and crushing them three times, each time for 3 minutes, to obtain Sedum powder; then, adding 5g of Sedum powder and 50g of a second deep eutectic solvent into a container, heating it to 130°C and stirring it for 6 hours to extract heavy metals, polysaccharides, and lignin from the Sedum, and then centrifuging to obtain the supernatant, which is the Sedum extract solution.

[0042] The steps of cross-linking and molding the conductive hydrogel include: weighing 12g of citric acid, 20g of deionized water, 12g of polyvinyl alcohol, 20g of feather keratin solution, and 36g of sedum extract solution in a mass ratio of 12:20:12:20:36, respectively; first dissolving the citric acid in deionized water, heating to 90°C, and adding polyvinyl alcohol to swell for 10 minutes; then adding the feather keratin solution and the sedum extract solution, heating to 130°C, reacting for 10 minutes, and then transferring to a polytetrafluoroethylene mold, then naturally cooling to room temperature, and standing for a period of time to obtain a conductive hydrogel.

[0043] Example 2

[0044] This embodiment 2 provides a method for preparing a conductive hydrogel from waste biomass using a deep eutectic solvent, including a step of preparing a deep eutectic solvent, a step of processing chicken feathers, a step of processing Sedum, and a step of cross-linking and forming the conductive hydrogel.

[0045] The steps for preparing a deep eutectic solvent include:

[0046] The hydrogen bond acceptor urea and the hydrogen bond donor ethylene glycol were weighed in a molar ratio of 1:2, 0.5 mol of urea and 1 mol of ethylene glycol were respectively added to a reaction vessel, and the mixture was heated at 100°C for 30 minutes to form a homogeneous liquid, thereby obtaining a first deep eutectic solvent; the hydrogen bond acceptor choline chloride and the hydrogen bond donor lactic acid were weighed in a molar ratio of 1:10, 0.1 mol of choline chloride and 1 mol of lactic acid were respectively added to a reaction vessel, and the mixture was heated at 100°C for 30 minutes to form a homogeneous liquid, thereby obtaining a second deep eutectic solvent.

[0047] The chicken feather processing steps include: first, cutting the chicken feathers collected from the market into small pieces with a tool, placing them in a grinder and crushing them three times, each time for 3 minutes, to obtain uniform chicken feather powder; then, adding 2.5g of the chicken feather powder and 50g of the first deep eutectic solvent into a container, heating it to 120°C and stirring it for 3 hours to extract feather keratin from the chicken feathers, and then centrifuging to obtain the supernatant, which is the feather keratin solution.

[0048] The processing steps of Sedum include: first, cutting Sedum plants collected near the mining area into small pieces with tools, placing them in a grinder and crushing them three times, each time for 3 minutes, to obtain Sedum powder; then, adding 5g of Sedum powder and 50g of a second deep eutectic solvent into a container, heating it to 130°C and stirring it for 6 hours to extract heavy metals, polysaccharides, and lignin from the Sedum, and then centrifuging to obtain the supernatant, which is the Sedum extract solution.

[0049] The steps of cross-linking and molding the conductive hydrogel include: weighing 12g of citric acid, 35g of deionized water, 12g of polyvinyl alcohol, 20g of feather keratin solution, and 21g of sedum extract solution in a mass ratio of 12:35:12:20:21, respectively; first dissolving the citric acid in deionized water, heating to 90°C, and adding polyvinyl alcohol to swell for 10 minutes; then adding the feather keratin solution and the sedum extract solution, and heating to 130°C. After reacting for 10 minutes, transfer to a polytetrafluoroethylene mold, and then naturally cool to room temperature. After standing for a period of time, the conductive hydrogel is obtained.

[0050] Example 3

[0051] This Example 3 provides a method for preparing a conductive hydrogel from waste biomass using a deep eutectic solvent, including a step of preparing a deep eutectic solvent, a step of processing chicken feathers, a step of processing Sedum, and a step of cross-linking and forming the conductive hydrogel.

[0052] The steps for preparing a deep eutectic solvent include:

[0053] The hydrogen bond acceptor urea and the hydrogen bond donor ethylene glycol were weighed in a molar ratio of 1:2, 0.5 mol of urea and 1 mol of ethylene glycol were respectively added to a reaction vessel, and the mixture was heated at 100°C for 30 minutes to form a homogeneous liquid, thereby obtaining a first deep eutectic solvent; the hydrogen bond acceptor choline chloride and the hydrogen bond donor lactic acid were weighed in a molar ratio of 1:10, 0.1 mol of choline chloride and 1 mol of lactic acid were respectively added to a reaction vessel, and the mixture was heated at 100°C for 30 minutes to form a homogeneous liquid, thereby obtaining a second deep eutectic solvent.

[0054] The chicken feather processing steps include: first, cutting the chicken feathers collected from the market into small pieces with a tool, placing them in a grinder and crushing them three times, each time for 3 minutes, to obtain uniform chicken feather powder; then, adding 2.5g of the chicken feather powder and 50g of the first deep eutectic solvent into a container, heating it to 120°C and stirring it for 3 hours to extract feather keratin from the chicken feathers, and then centrifuging to obtain the supernatant, which is the feather keratin solution.

[0055] The processing steps of Sedum include: first, cutting Sedum plants collected near the mining area into small pieces with tools, placing them in a grinder and crushing them three times, each time for 3 minutes, to obtain Sedum powder; then, adding 5g of Sedum powder and 50g of a second deep eutectic solvent into a container, heating it to 130°C and stirring it for 6 hours to extract heavy metals, polysaccharides, and lignin from the Sedum, and then centrifuging to obtain the supernatant, which is the Sedum extract solution.

[0056] The steps of cross-linking and molding the conductive hydrogel include: weighing 12g of citric acid, 30g of deionized water, 12g of polyvinyl alcohol, 30g of feather keratin solution, and 16g of sedum extract solution in a mass ratio of 12:30:12:30:16, first dissolving the citric acid in deionized water, heating to 90°C, and adding polyvinyl alcohol to swell for 10 minutes, then adding the feather keratin solution and the sedum extract solution, and heating to 130°C. After reacting for 10 minutes, transfer to a polytetrafluoroethylene mold, and then naturally cool to room temperature. After standing for a period of time, the conductive hydrogel is obtained.

[0057] Example 4

[0058] This embodiment 4 provides a method for preparing a conductive hydrogel from waste biomass using a deep eutectic solvent, including a step of preparing a deep eutectic solvent, a step of processing chicken feathers, a step of processing Sedum, and a step of cross-linking and forming the conductive hydrogel.

[0059] The steps for preparing a deep eutectic solvent include:

[0060] The hydrogen bond acceptor urea and the hydrogen bond donor ethylene glycol were weighed in a molar ratio of 1:2, 0.5 mol of urea and 1 mol of ethylene glycol were respectively added to a reaction vessel, and the mixture was heated at 100°C for 30 minutes to form a homogeneous liquid, thereby obtaining a first deep eutectic solvent; the hydrogen bond acceptor choline chloride and the hydrogen bond donor lactic acid were weighed in a molar ratio of 1:10, 0.1 mol of choline chloride and 1 mol of lactic acid were respectively added to a reaction vessel, and the mixture was heated at 100°C for 30 minutes to form a homogeneous liquid, thereby obtaining a second deep eutectic solvent.

[0061] The chicken feather processing steps include: first, cutting the chicken feathers collected from the market into small pieces with a tool, placing them in a grinder and crushing them three times, each time for 3 minutes, to obtain uniform chicken feather powder; then, adding 2.5g of the chicken feather powder and 50g of the first deep eutectic solvent into a container, heating it to 120°C and stirring it for 3 hours to extract feather keratin from the chicken feathers, and then centrifuging to obtain the supernatant, which is the feather keratin solution.

[0062] The processing steps of Sedum include: first, cutting Sedum plants collected near the mining area into small pieces with tools, placing them in a grinder and crushing them three times, each time for 3 minutes, to obtain Sedum powder; then, adding 5g of Sedum powder and 50g of a second deep eutectic solvent into a container, heating it to 130°C and stirring it for 6 hours to extract heavy metals, polysaccharides, and lignin from the Sedum, and then centrifuging to obtain the supernatant, which is the Sedum extract solution.

[0063] The steps of cross-linking and molding the conductive hydrogel include: weighing 12g of citric acid, 35g of deionized water, 12g of polyvinyl alcohol, 40g of feather keratin solution, and 1g of sedum extract solution respectively in a mass ratio of 12:35:12:40:1, first dissolving the citric acid in deionized water, heating to 90°C, and adding polyvinyl alcohol to swell for 10 minutes, then adding the feather keratin solution and the sedum extract solution, and heating to 130°C. After reacting for 10 minutes, transfer to a polytetrafluoroethylene mold, then naturally cool to room temperature, and stand for a period of time to obtain a conductive hydrogel.

[0064] Example 5

[0065] This Example 5 provides a method for preparing a conductive hydrogel by developing waste biomass using a deep eutectic solvent. The difference between the preparation method and Example 1 lies in the step of cross-linking the conductive hydrogel.

[0066] The steps of cross-linking and molding the conductive hydrogel in this embodiment include: weighing 12 g of citric acid, 30 g of deionized water, 12 g of polyvinyl alcohol, 20 g of feather keratin solution, and 26 g of sedum extract solution in a mass ratio of 12:30:12:20:26, respectively; first dissolving the citric acid in deionized water, heating to 90° C., and adding polyvinyl alcohol to swell for 10 minutes; then adding the feather keratin solution and the sedum extract solution, heating to 130° C., reacting for 10 minutes, and then transferring to a polytetrafluoroethylene mold, then naturally cooling to room temperature, and standing for a period of time to obtain the conductive hydrogel.

[0067] Example 6

[0068] This Example 6 provides a method for preparing a conductive hydrogel by developing waste biomass using a deep eutectic solvent. The difference between the preparation method and Example 1 lies in the step of cross-linking and forming the conductive hydrogel.

[0069] The steps of cross-linking and molding the conductive hydrogel in this embodiment include: weighing 12 g of citric acid, 20 g of deionized water, 12 g of polyvinyl alcohol, 30 g of feather keratin solution, and 26 g of sedum extract solution in a mass ratio of 12:20:12:30:26, respectively; first dissolving the citric acid in deionized water, heating to 90° C., and adding polyvinyl alcohol to swell for 10 minutes; then adding the feather keratin solution and the sedum extract solution, heating to 130° C., reacting for 10 minutes, and then transferring to a polytetrafluoroethylene mold, then naturally cooling to room temperature, and standing for a period of time to obtain a conductive hydrogel.

[0070] Example 7

[0071] This Example 7 provides a method for preparing a conductive hydrogel by developing waste biomass using a deep eutectic solvent. The difference between the preparation method and Example 1 lies in the step of cross-linking the conductive hydrogel.

[0072] The steps of cross-linking and molding the conductive hydrogel in this embodiment include: weighing 12 g of citric acid, 35 g of deionized water, 12 g of polyvinyl alcohol, 30 g of feather keratin solution, and 11 g of sedum extract solution in a mass ratio of 12:35:12:30:11, respectively; first dissolving the citric acid in deionized water, heating to 90° C., and adding polyvinyl alcohol to swell for 10 minutes; then adding the feather keratin solution and the sedum extract solution, heating to 130° C., reacting for 10 minutes, and then transferring to a polytetrafluoroethylene mold, then naturally cooling to room temperature, and standing for a period of time to obtain the conductive hydrogel.

[0073] Example 8

[0074] This Example 8 provides a method for preparing a conductive hydrogel by developing waste biomass using a deep eutectic solvent. The difference between the preparation method and Example 1 lies in the step of cross-linking the conductive hydrogel.

[0075] The steps of cross-linking and molding the conductive hydrogel in this embodiment include: weighing 12 g of citric acid, 20 g of deionized water, 12 g of polyvinyl alcohol, 40 g of feather keratin solution, and 16 g of sedum extract solution in a mass ratio of 12:20:12:40:16, respectively; first dissolving the citric acid in deionized water, heating to 90° C., and adding polyvinyl alcohol to swell for 10 minutes; then adding the feather keratin solution and the sedum extract solution, heating to 130° C., reacting for 10 minutes, and then transferring to a polytetrafluoroethylene mold, then naturally cooling to room temperature, and standing for a period of time to obtain the conductive hydrogel.

[0076] Example 9

[0077] This Example 9 provides a method for preparing a conductive hydrogel by developing waste biomass using a deep eutectic solvent. The difference between the preparation method and Example 1 lies in the step of cross-linking and forming the conductive hydrogel.

[0078] The steps of cross-linking and molding the conductive hydrogel in this embodiment include: weighing 12 g of citric acid, 30 g of deionized water, 12 g of polyvinyl alcohol, 40 g of feather keratin solution, and 6 g of sedum extract solution in a mass ratio of 12:30:12:40:6, respectively; first dissolving the citric acid in deionized water, heating to 90° C., and adding polyvinyl alcohol to swell for 10 minutes; then adding the feather keratin solution and the sedum extract solution, heating to 130° C., reacting for 10 minutes, and then transferring to a polytetrafluoroethylene mold, then naturally cooling to room temperature, and standing for a period of time to obtain a conductive hydrogel.

[0079] Example 10

[0080] This Example 10 provides a method for preparing a conductive hydrogel by developing waste biomass using a deep eutectic solvent. The difference between the preparation method and Example 1 lies in the step of cross-linking and forming the conductive hydrogel.

[0081] The steps of cross-linking and molding the conductive hydrogel in this embodiment include: weighing 12 g of citric acid, 25 g of deionized water, 12 g of polyvinyl alcohol, 20 g of feather keratin solution, and 31 g of sedum extract solution in a mass ratio of 12:25:12:20:31, respectively; first dissolving the citric acid in deionized water, heating to 90° C., and adding polyvinyl alcohol to swell for 10 minutes; then adding the feather keratin solution and the sedum extract solution, heating to 130° C., reacting for 10 minutes, and then transferring to a polytetrafluoroethylene mold, then naturally cooling to room temperature, and standing for a period of time to obtain the conductive hydrogel.

[0082] Example 11

[0083] This Example 11 provides a method for preparing a conductive hydrogel by developing waste biomass using a deep eutectic solvent. The difference between the preparation method and Example 1 lies in the step of cross-linking and forming the conductive hydrogel.

[0084] The steps of cross-linking and molding the conductive hydrogel in this embodiment include: weighing 12 g of citric acid, 25 g of deionized water, 12 g of polyvinyl alcohol, 30 g of feather keratin solution, and 21 g of sedum extract solution in a mass ratio of 12:25:12:30:21, respectively; first dissolving the citric acid in deionized water, heating to 90° C., and adding polyvinyl alcohol to swell for 10 minutes; then adding the feather keratin solution and the sedum extract solution, heating to 130° C., reacting for 10 minutes, and then transferring to a polytetrafluoroethylene mold, then naturally cooling to room temperature, and standing for a period of time to obtain the conductive hydrogel.

[0085] Example 12

[0086] This Example 12 provides a method for preparing a conductive hydrogel by developing waste biomass using a deep eutectic solvent. The difference between the preparation method and Example 1 lies in the step of cross-linking and forming the conductive hydrogel.

[0087] The steps of cross-linking and molding the conductive hydrogel in this embodiment include: weighing 12 g of citric acid, 40 g of deionized water, 12 g of polyvinyl alcohol, 30 g of feather keratin solution, and 6 g of sedum extract solution in a mass ratio of 12:40:12:30:6, respectively; first dissolving the citric acid in deionized water, heating to 90° C., and adding polyvinyl alcohol to swell for 10 minutes; then adding the feather keratin solution and the sedum extract solution, heating to 130° C., reacting for 10 minutes, and then transferring to a polytetrafluoroethylene mold, then naturally cooling to room temperature, and standing for a period of time to obtain the conductive hydrogel.

[0088] Example 13

[0089] This Example 13 provides a method for preparing a conductive hydrogel by developing waste biomass using a deep eutectic solvent. The difference between the preparation method and Example 1 lies in the step of cross-linking and forming the conductive hydrogel.

[0090] The steps of cross-linking and molding the conductive hydrogel in this embodiment include: weighing 12 g of citric acid, 40 g of deionized water, 12 g of polyvinyl alcohol, 20 g of feather keratin solution, and 16 g of sedum extract solution in a mass ratio of 12:40:12:20:16, respectively; first dissolving the citric acid in deionized water, heating to 90° C., and adding polyvinyl alcohol to swell for 10 minutes; then adding the feather keratin solution and the sedum extract solution, heating to 130° C., reacting for 10 minutes, and then transferring to a polytetrafluoroethylene mold, then naturally cooling to room temperature, and standing for a period of time to obtain a conductive hydrogel.

[0091] Example 14

[0092] This Example 14 provides a method for preparing a conductive hydrogel by developing waste biomass using a deep eutectic solvent. The difference between the preparation method and Example 1 lies in the step of cross-linking and forming the conductive hydrogel.

[0093] The steps of cross-linking and molding the conductive hydrogel in this embodiment include: weighing 12 g of citric acid, 25 g of deionized water, 12 g of polyvinyl alcohol, 40 g of feather keratin solution, and 11 g of sedum extract solution in a mass ratio of 12:25:12:40:11, respectively; first dissolving the citric acid in deionized water, heating to 90° C., and adding polyvinyl alcohol to swell for 10 minutes; then adding the feather keratin solution and the sedum extract solution, heating to 130° C., reacting for 10 minutes, and then transferring to a polytetrafluoroethylene mold, then naturally cooling to room temperature, and standing for a period of time to obtain the conductive hydrogel.

[0094] Comparative Example 1

[0095] This comparative example 1 provides a method for preparing a keratin hydrogel, comprising a step of preparing a deep eutectic solvent, a step of processing chicken feathers, and a step of cross-linking and forming the keratin hydrogel.

[0096] The steps for preparing a deep eutectic solvent include:

[0097] The hydrogen bond acceptor urea and the hydrogen bond donor ethylene glycol were weighed in a molar ratio of 1:2, 0.5 mol of urea and 1 mol of ethylene glycol were respectively added to a reaction vessel, and heated at 100° C. for 30 minutes to form a homogeneous liquid, thereby obtaining a first deep eutectic solvent.

[0098] The chicken feather processing steps include: first, cutting the chicken feathers collected from the market into small pieces with a tool, placing them in a grinder and crushing them three times, each time for 3 minutes, to obtain uniform chicken feather powder; then, adding 2.5g of the chicken feather powder and 50g of the first deep eutectic solvent into a container, heating it to 120°C and stirring it for 3 hours to extract feather keratin from the chicken feathers, and then centrifuging to obtain the supernatant, which is the feather keratin solution.

[0099] The steps of cross-linking and molding the keratin hydrogel include: weighing 12 g of citric acid, 30 g of deionized water, 12 g of polyvinyl alcohol, and 30 g of feather keratin solution in a mass ratio of 12:30:12:30, dissolving the citric acid in deionized water, heating it to 90° C., adding polyvinyl alcohol to swell for 10 minutes, then adding the feather keratin solution, heating it to 130° C., reacting for 10 minutes, and then transferring it to a polytetrafluoroethylene mold, then naturally cooling it to room temperature, and standing it for a period of time to obtain the keratin hydrogel.

[0100] Comparative Example 2

[0101] This comparative example 2 provides a method for preparing a conductive hydrogel, which includes a solvent preparation step and a conductive hydrogel cross-linking molding step.

[0102] The solvent preparation steps include:

[0103] 1 mol of urea and 0.5 mol of choline chloride were weighed and added to a reaction vessel at a molar ratio of 2:1, and heated at 100° C. for 30 minutes to form a homogeneous liquid to obtain a first solvent.

[0104] The steps of cross-linking the conductive hydrogel include:

[0105] 6 g of α-methylacrylic acid (MAA), 0.3 g of pyrrole (Py), and 1.5 mL of NN´-methylenebisacrylamide (MBA, concentration of 2 g L -1) and 24.7 g of the first solvent were added to a beaker, and 0.03 g of KPS powder was added to the beaker and dissolved by stirring. The eutectic gel was then polymerized in a 65°C water bath for 1 hour to obtain a conductive hydrogel.

[0106] Comparative Example 3

[0107] This comparative example 3 provides a method for preparing a conductive hydrogel, including a step of preparing a deep eutectic solvent and a step of cross-linking and forming the conductive hydrogel.

[0108] The steps for preparing a deep eutectic solvent include:

[0109] 0.5 mol of ChCl, 1 mol of glycerol, and 0.01 mol of AlCl3·6H2O were weighed in a molar ratio of 50:100:1, mixed, and magnetically stirred at 60°C for 30 min until the solution became clear and transparent to obtain a deep eutectic solvent DES. The poplar wood was then placed in a vacuum oven and dried at 60°C for 12 h to remove moisture. The dried poplar wood was added to the prepared deep eutectic solvent DES at a solid-to-liquid ratio of 1:15, and the mixture was reacted at 140°C for 1 h. The reaction solution was filtered through a Buchner funnel to obtain a pretreated DES solution.

[0110] The steps of cross-linking the conductive hydrogel include:

[0111] The pretreated DES solution was mixed with 33 g of acrylic acid (AA) and 50 g of polyvinyl alcohol (PVA) solution, and then 0.2 g of N,N-methylenebisacrylamide (MBA) and 0.5 g of ammonium persulfate (APS) were added. The mixed solution was poured into a mold and allowed to stand for a period of time to obtain a conductive hydrogel.

[0112] Experimental Example 1

[0113] In this experimental example 1, the hydrogels provided by Examples 1-4 and Comparative Examples 1-3 were subjected to performance tests. The performance tests included antifreeze performance tests, mechanical performance tests, and electrical conductivity tests. The test results are shown in Tables 1 and Figure 1 shown.

[0114] Table 1: Hydrogel properties provided by Examples 1-4 and Comparative Examples 1-3

[0115]

[0116] from Figure 1It can be seen that the hydrogels provided in Example 1 and Comparative Example 1 have excellent antifreeze properties; however, it can be seen from Table 1 that the conductive hydrogels provided in Examples 1-4 have excellent electrical conductivity and good mechanical properties, while the keratin hydrogel provided in Comparative Example 1 has no electrical conductivity and average mechanical properties. This is because the keratin hydrogel provided in Comparative Example 1 does not introduce the sedum extract solution obtained by treating sedum with a choline chloride / lactic acid deep eutectic solvent during the preparation process, and thus does not contain components such as heavy metals, polysaccharides, and lignin, and cannot achieve conductivity by means of electron migration or ion migration; at the same time, the mechanical properties of the hydrogel provided in Comparative Example 1 are poor. The performance is slightly higher than that of the hydrogel provided in Example 1, but lower than that of the hydrogel provided in Example 3. This is because the amount of keratin added to the hydrogel provided in Comparative Example 1 is higher than that in the hydrogel provided in Example 1. The keratin content in the hydrogel provided in Example 1 is too low, and the content of functional components such as polysaccharides and lignin in the Sedum extract solution is relatively high, which reduces the cross-linking density and leads to stress concentration defects. After increasing the keratin content, for example, after adding more keratin and appropriately reducing the content of Sedum extract in Example 3, it can produce a positive synergistic effect with the functional components such as polysaccharides and lignin in the Sedum extract solution, thereby achieving improved mechanical properties.

[0117] At the same time, it can be seen from Table 1 that the antifreeze performance of the hydrogels provided by Comparative Documents 2-3 is average. This is because the deep eutectic solvent DES used in Comparative Example 3 is mainly glycerol, while the one provided in Comparative Example 2 adds too much urea. The high proportion of urea may cause favorable molecules in the system to aggregate and form crystallization nuclei. Moreover, the viscosity of the system may be higher at low temperatures, molecular motion is restricted, and ice crystals are more likely to grow. This makes the antifreeze performance of the two inferior to that of DES such as urea / ethylene glycol and choline chloride / lactic acid. The DES such as urea / ethylene glycol and choline chloride / lactic acid used in Examples 1-4 can construct a hydrogen bond network structure. When added to water, water molecules will be integrated into the DES hydrogen bond network as new components, destroying the ordered structure between the water molecules. The water molecules lose the environment and "freedom" required to form their own regular ice crystal structure, inhibiting crystallization and improving the antifreeze performance of the hydrogel.

[0118] Experimental Example 2

[0119] In order to further explore the effects of feather keratin solution and sedum extract solution on the performance of conductive hydrogel, this experimental example conducted performance tests on the conductive hydrogels provided in Examples 1-14. The performance tests included mechanical properties and conductive properties tests. The performance test results are shown in FIG. Figure 2-3 shown.

[0120] The mechanical properties of the conductive hydrogels prepared by adding different amounts of feather keratin solutions are as follows: Figure 2 shown; from Figure 2It can be seen that the elongation at break and tensile strength of the conductive hydrogels provided in Examples 2-3 are relatively excellent, and they are conductive hydrogels with excellent comprehensive mechanical properties. The conductive properties of the conductive hydrogels prepared from the Sedum extract solutions of different qualities are shown in FIG. Figure 3 As shown, from Figure 3 It can be seen that when a larger amount of Sedum extract solution is added, such as the conductive hydrogel provided in Example 1, its continuous charge transfer path dominated by high electron migration makes it have excellent conductive properties. Although the conductive hydrogel provided in Example 4 has a smaller amount of Sedum extract solution added, the ion migration of chloride ions / lactate ions ensures a continuous charge transfer path, making it have better conductivity; it can also be seen that the conductive hydrogel provided in Example 3, that is, when water, keratin, and Sedum account for 30%, 30%, and 16% respectively, has better conductivity. Comprehensive mechanical property tests show that the conductive hydrogel provided in Example 3 is a relatively ideal conductive hydrogel, which has excellent elongation at break and tensile strength, good mechanical properties, stable structure, and good conductivity, and is therefore a flexible hydrogel sensor or flexible hydrogel electrode that is expected to be practically applied to the fields of flexible electronics, biomedicine, energy storage, and the like.

[0121] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing conductive hydrogel from waste biomass using a deep eutectic solvent, characterized in that: The following steps are involved: The steps for preparing a deep eutectic solvent are as follows: a hydrogen bond acceptor and a hydrogen bond donor are mixed and then heated to obtain a deep eutectic solvent; The poultry feather processing steps include: crushing the poultry feathers into feather powder, mixing with a deep eutectic solvent, heating and stirring, and centrifuging to obtain a feather keratin solution; The plant biomass processing steps include: crushing the plant biomass containing heavy metals into plant biomass powder, mixing with a deep eutectic solvent, heating and stirring, and centrifuging to obtain a plant biomass extract solution; The conductive hydrogel cross-linking molding step is as follows: mixing and heating a hydroxyl-containing auxiliary gel-forming polymer, a cross-linking agent, an aqueous solution, a feather keratin solution and a plant biomass extract solution, and then placing the mixture in a mold and cooling it to room temperature to obtain a conductive hydrogel.

2. The method for preparing conductive hydrogel from waste biomass using a deep eutectic solvent according to claim 1, characterized in that: In the step of preparing the deep eutectic solvent, the hydrogen bond acceptor used is selected from at least one of choline chloride, urea, and betaine, and the hydrogen bond donor used is selected from at least one of lactic acid, ethylene glycol, glycerol, tartaric acid, oxalic acid, and malic acid.

3. The method for preparing conductive hydrogel from waste biomass using a deep eutectic solvent according to claim 1, characterized in that: In the poultry feather processing step, the poultry feathers used are selected from at least one of chicken feathers, duck feathers and goose feathers.

4. The method for preparing conductive hydrogel from waste biomass using a deep eutectic solvent according to claim 1, characterized in that: In the step of treating plant biomass, the plant biomass containing heavy metals is selected from at least one of Sedum multiflorum, Phytolacca americana, and Cyperus rotundus.

5. The method for preparing conductive hydrogel from waste biomass using a deep eutectic solvent according to claim 1, characterized in that: In the step of cross-linking the conductive hydrogel, the hydroxyl-containing auxiliary gel-forming polymer used is selected from at least one of polyvinyl alcohol, polyacrylic acid, hyaluronic acid, and chitosan, and the cross-linking agent used is selected from at least one of citric acid, tartaric acid, oxalic acid, and malic acid.

6. The method for preparing conductive hydrogel from waste biomass using a deep eutectic solvent according to claim 1, characterized in that: In the poultry feather processing step, the mass ratio of chicken feather powder to deep eutectic solvent is 0.2~2:10, the heating and stirring temperature is 90~150℃, and the time is 1~5h.

7. The method for preparing conductive hydrogel from waste biomass using a deep eutectic solvent according to claim 1, characterized in that: In the processing step of plant biomass, the mass ratio of chicken feather powder to deep eutectic solvent is 0.5~3:10, the heating and stirring temperature is 100~150℃, and the time is 3~10h.

8. The method for preparing conductive hydrogel from waste biomass using a deep eutectic solvent according to claim 1, characterized in that: The steps of cross-linking and forming the conductive hydrogel specifically include: Step S1, dissolving a crosslinking agent in an aqueous solution at 80-100° C., then adding a hydroxyl-containing auxiliary gel-forming polymer, mixing and heating for 5-15 minutes to obtain a polymer solution; Step S2: mixing the feather keratin solution, the plant biomass extract solution, and the polymer solution and heating them at 100-150° C. for 5-15 minutes to obtain a conductive hydrogel precursor solution; Step S3: placing the conductive hydrogel precursor solution in a mold and cooling it to room temperature to obtain a conductive hydrogel precursor.

9. The method for preparing conductive hydrogel from waste biomass using a deep eutectic solvent according to claim 1, characterized in that: Calculated by mass, the conductive hydrogel precursor solution includes: 10-15 mass parts of hydroxyl-containing auxiliary gel-forming polymer, 10-15 mass parts of cross-linking agent, 20-40 mass parts of aqueous solution, 20-40 mass parts of feather keratin solution, and 1-40 mass parts of plant biomass extract solution.

10. The conductive hydrogel prepared by the method for preparing conductive hydrogel from waste biomass using a deep eutectic solvent according to any one of claims 1 to 9 is used in the fields of flexible electronics, biomedicine or energy storage.

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