Ternary system coagulating bath and prepared hydrogel fiber

Abstract

The invention discloses a ternary system coagulating bath and a prepared hydrogel fiber, and belongs to the technical field of polymer hydrogel. The ternary system coagulating bath comprises a hydrogen bond donor and a hydrogen bond acceptor in a molar ratio of not less than 1: 1, and a reinforcing agent accounting for 0.5-2wt% of the total mass of the hydrogen bond donor and the hydrogen bond acceptor; the total content of the hydrogen bond donor and the hydrogen bond acceptor at least accounts for 70wt% of the ternary system coagulating bath; and the balance of water. Wherein the hydrogen bond donor is an organic small molecule containing a Lewis acid site; the hydrogen bond acceptor is a metal organic complex containing Lewis alkaline sites; the reinforcing agent is one or more of graphene oxide, a carbon nano tube or poly (3, 4-ethylenedioxythiophene)-poly (styrene sulfonic acid). The prepared hydrogel fiber is good in mechanical property and conductivity, the breaking strength is not lower than 0.4 MPa, the elongation at break is not lower than 190%, and the conductivity is not lower than 2S / m.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer hydrogels, and more specifically, to a ternary system coagulation bath and the hydrogel fibers prepared therefrom. Background Art

[0002] Due to their good biocompatibility and high water content, hydrogels are widely used in the fields of bioengineering and materials science. Most hydrogels exist in the form of blocks or membranes, but their size and shape are fixed. Hydrogel fibers have unique morphological and structural advantages compared to hydrogel blocks and can be applied to more scenarios.

[0003] In the prior art, the preparation of hydrogel fibers mostly relies on chemical cross-linking or single-ion coagulation, and has the following deficiencies: the coagulation bath mechanism is single, the function is single, it is difficult to simultaneously have mechanical properties, high water content performance and biological functions, and the process is complex, generally requiring multiple steps of chemical cross-linking, ultraviolet curing or high-temperature treatment, and the equipment and process costs are high. In recent years, deep eutectic solvents (DESs) have gradually replaced traditional organic solvents (such as DMSO) and inorganic salt systems (such as CaCl2 / ethylene glycol) in the field of fiber spinning coagulation baths due to their low toxicity, biodegradability and designability. However, the existing DESs coagulation bath technology still has the following bottlenecks: single functionality. Currently, the mainstream DESs systems (such as choline chloride / urea, choline chloride / ethylene glycol) mainly focus on the basic physical and chemical properties of the solvent (such as viscosity) and lack value-added functions such as conductivity. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above deficiencies or defects, and to provide a ternary system coagulation bath, which can enable the prepared hydrogel fibers to have high mechanical properties and conductivity through the synergism of a hydrogen bond acceptor, a hydrogen bond donor and an enhancer.

[0005] Another purpose of the present invention is to provide the application of the ternary system coagulation bath.

[0006] Another purpose of the present invention is to provide a hydrogel fiber.

[0007] To achieve the above purpose, the present invention is realized through the following technical solutions: A ternary system coagulation bath, comprising a hydrogen bond donor and a hydrogen bond acceptor with a molar ratio of not less than 1:1, and an enhancer accounting for 0.5-2 wt% of the total mass of the hydrogen bond donor and the hydrogen bond acceptor; the total content of the hydrogen bond donor and the hydrogen bond acceptor accounts for at least 70 wt% of the ternary system coagulation bath; the balance is water; Among them, the hydrogen bond donor is an organic small molecule containing Lewis acidic sites; the hydrogen bond acceptor is a metal-organic complex containing Lewis basic sites; the enhancer is one or more of graphene oxide, carbon nanotubes or poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid).

[0008] The present invention provides a ternary system coagulation bath. By synergistically using specific hydrogen bond acceptors, hydrogen bond donors and enhancers, the prepared hydrogel fibers have good mechanical properties and conductivity. Specifically, the Lewis acidic sites in the hydrogen bond donor can provide hydrogen bond protons to the hydrogen bond acceptor. During the interaction with the hydrogen bond acceptor, a stable and continuous hydrogen bond connection network can be constructed. At the same time, its flexible molecular backbone allows the internal conformation to be adjusted at the microscopic scale, thereby improving the adaptability of the whole system to stress or structural disturbances, and contributing to the construction of a composite solvent system with good viscoelasticity and outstanding energy dissipation performance; the hydrogen bond acceptor is a metal-organic complex containing Lewis basic sites, which can effectively attract and fix the hydrogen bond acceptor. In addition, the metal centers contained in such hydrogen bond acceptors can play a guiding role in the arrangement of surrounding donor molecules, thereby forming locally ordered aggregation regions inside the hydrogen bond network. The reversible complexation behavior between the metal and the ligand also endows the network with a certain dynamic regulation ability, which helps the material to maintain structural integrity and achieve self-regulation of performance under external environmental changes (such as temperature, shear, etc.); the enhancer in the system itself does not participate in the main chain chemical cross-linking, but can provide high-density adsorption sites in the hydrogen bond network, thereby inducing the spatial reconstruction of the network. Through non-covalent interactions with surrounding molecules, such as hydrogen bonds or interfacial adsorption, such enhancing components improve the structural density and stability of the network, and at the same time limit the segmental motion to a certain extent and enhance the rigidity of the system. The inventors surprisingly found that adding an enhancer to this system can improve the mechanical properties of the prepared hydrogel fibers while improving their electrical conductivity.

[0009] It should be noted that the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor in the present invention is not less than 1:1, such as but not limited to not less than 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2, 1:2.2, 1:2.5, 1:2.8, 1:3, 1:3.2, 1:3.5, 1:3.8 or 1:4, etc., as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the specific point values included in the scope of the present invention are not exhaustively listed herein.

[0010] Furthermore, the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor is 1:1 to 3:1.

[0011] It should be noted that the enhancer accounts for 0.5-2 wt% of the total mass of the hydrogen bond donor and the hydrogen bond acceptor, such as, but not limited to, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt% or 2 wt%, etc., as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the specific point values included in the scope of the present invention are not exhaustively listed herein.

[0012] It should be noted that the total content of the hydrogen bond donor and the hydrogen bond acceptor accounts for at least 70 wt% of the ternary system coagulation bath, such as, but not limited to, at least 70 wt%, 72 wt%, 75 wt%, 78 wt%, 80 wt%, 82 wt%, 85 wt% or 90 wt% of the ternary system coagulation bath, etc., as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the specific point values included in the scope of the present invention are not exhaustively listed herein.

[0013] Furthermore, the total content of the hydrogen bond donor and the hydrogen bond acceptor accounts for at least 70-85 wt% of the ternary system coagulation bath.

[0014] Furthermore, the hydrogen bond donor is one or more of levulinic acid, lactic acid, malic acid or citric acid.

[0015] Even further, the hydrogen bond acceptor is lactic acid and / or citric acid.

[0016] Furthermore, the hydrogen bond acceptor is one or more of zinc gluconate, calcium gluconate, magnesium gluconate, calcium lactate or zinc citrate.

[0017] Even further, the hydrogen bond acceptor is calcium lactate and / or zinc gluconate.

[0018] Furthermore, the enhancer is graphene oxide.

[0019] In some preferred specific embodiments, the graphene oxide is monolayer graphene oxide, the sheet diameter of the graphene oxide is 0.5-5 μm, and the thickness is 0.8-1.2 nm.

[0020] The present invention also provides a method for preparing a hydrogel fiber, comprising the following steps: Extruding the spinning solution into the above-mentioned ternary system coagulation bath, and then successively performing thermal strengthening, freezing strengthening and drying to obtain.

[0021] Furthermore, the spinning solution is one or more of an aqueous solution of polyvinyl alcohol, an aqueous solution of polyvinyl alcohol-sodium alginate or an aqueous solution of polyvinyl alcohol-nanocellulose.

[0022] It should be noted that when the spinning solution is an aqueous solution of polyvinyl alcohol - sodium alginate, the ternary system coagulation bath further includes calcium chloride accounting for 3 - 8 wt% of the ternary system coagulation bath.

[0023] In some preferred embodiments, the mass concentration of the spinning solution is 8 - 15 wt%.

[0024] In some preferred embodiments, the degree of polymerization of the polyvinyl alcohol is 1600 - 1800.

[0025] In some preferred embodiments, the spinning solution is obtained by dissolving polyvinyl alcohol and sodium alginate with a mass ratio of 3:1 at 10 wt% in water, stirring at 80 °C for 30 min, and degassing at room temperature for 10 min.

[0026] In some preferred embodiments, the extrusion is carried out by an injection pump, and the flow rate is controlled at 0.1 mL / min, and extruded through a 23G spinneret (inner diameter 0.42 mm).

[0027] Specifically, the extrusion is aligned with the surface of the coagulation bath, and the spinning distance is 5 mm.

[0028] Furthermore, the temperature of the ternary system coagulation bath is 20 - 25 °C. The spinning solution can be instantaneously formed due to the hydrogen bond action in the ternary system coagulation bath after spinning into the coagulation bath.

[0029] Furthermore, the temperature of the thermal reinforcement is 37 - 60 °C.

[0030] Specifically, the coagulated and formed fibers are immersed in a 37 °C water bath for 5 min. The hydrogen bond donor interacts further with the spinning solution segments at this temperature to form a secondary physical network structure.

[0031] Furthermore, the freeze strengthening is specifically carried out by freezing at -20 °C for 2 h, thawing at room temperature for 2 h, and cycling 2 - 4 times. Phase separation and microcrystalline crystallization of the polyvinyl alcohol segments occur in the spinning solution after freeze strengthening to construct a tertiary physical network structure.

[0032] Furthermore, the drying is carried out by freeze drying or vacuum drying.

[0033] In some preferred specific embodiments, the freeze - strengthened fibers are rinsed to remove residual small molecules before drying.

[0034] Specifically, the temperature of the freeze drying is -40 °C, and the time of the freeze drying is 24 h.

[0035] Specifically, the temperature of the vacuum drying is 37 °C, and the time of the vacuum drying is 12 h.

[0036] The present invention also provides a hydrogel fiber prepared by the above preparation method.

[0037] Specifically, the average diameter of the hydrogel fiber is 60 - 250 nm.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a ternary system coagulation bath. By selecting specific hydrogen bond donors, hydrogen bond acceptors, and enhancers as the coagulation bath for hydrogel fiber spinning, the mechanical properties and electrical conductivity of the prepared hydrogel fiber can be effectively improved. The breaking strength is not less than 0.4 MPa, the elongation at break is not less than 190%, and the electrical conductivity is not less than 2 S / m. Description of the Drawings

[0039] Figure 1 It is a physical picture of the hydrogel fiber prepared in Example 4; Figure 2 It is a scanning electron microscope picture of the hydrogel fibers prepared in Examples 1 - 6; Figure 3 It is a scanning electron microscope picture of the hydrogel fibers prepared in Comparative Examples 1 and 2. Detailed Embodiments

[0040] The following further illustrates the present invention in conjunction with specific embodiments, but the embodiments do not impose any form of limitation on the present invention. Unless otherwise specified, the raw material reagents used in the embodiments of the present invention are conventional raw material reagents purchased.

[0041] Polyvinyl alcohol: degree of polymerization 1700; Graphene oxide: monolayer graphene oxide powder, Macklin reagent.

[0042] Example 1 A preparation method of a hydrogel fiber, comprising the following steps: S1. Ternary system coagulation bath: The molar ratio of hydrogen bond donor lactic acid to hydrogen bond acceptor zinc gluconate is 1:1, graphene oxide is 1 wt% of the total mass of the hydrogen bond donor and hydrogen bond acceptor, the hydrogen bond donor and hydrogen bond acceptor account for 80 wt% of the ternary system coagulation bath, 5 wt% calcium chloride, and the balance is water. Mix evenly to obtain the ternary system coagulation bath; S2. Spinning solution preparation: Dissolve polyvinyl alcohol - sodium alginate with a mass ratio of 3:1 in water at a concentration of 10 wt%, stir at 80 °C for 30 min, and degas at room temperature for 10 min to obtain the spinning solution; S3. Wet spinning: Place the spinning solution described in step S2 in an injection pump, control the flow rate at 0.1 mL / min, and extrude the spinning through a 23G spinneret (inner diameter 0.42 mm) facing the surface of the ternary system coagulation bath described in step S1 (temperature controlled at 22 °C) at a distance of 5 mm; S4. Thermal reinforcement: Immerse the fibers solidified and formed in step S3 in a 37°C water bath for 5 min; S5. Freezing enhancement: Freeze the fibers obtained in step S4 at -20°C for 2 h and thaw at room temperature for 2 h, and repeat the cycle 3 times; S6. Post-treatment and drying: Wash the fibers treated in step S5 with water 3 times to remove residual small molecules, and freeze-dry at -40°C for 24 h to obtain hydrogel fibers after shaping.

[0043] Example 2 A method for preparing hydrogel fibers, comprising the following steps: S1. Ternary system coagulation bath: The molar ratio of hydrogen bond donor lactic acid to hydrogen bond acceptor zinc gluconate is 2:1, graphene oxide is 1 wt% of the total mass of the hydrogen bond donor and hydrogen bond acceptor, the hydrogen bond donor and hydrogen bond acceptor account for 80 wt% of the ternary system coagulation bath, 5 wt% calcium chloride, and the balance is water. Mix evenly to obtain the ternary system coagulation bath; S2. Spinning solution preparation: Dissolve polyvinyl alcohol-sodium alginate with a mass ratio of 3:1 in water at a concentration of 10 wt%, stir at 80°C for 30 min, and defoam at room temperature for 10 min to obtain the spinning solution; S3. Wet spinning: Place the spinning solution described in step S2 in an injection pump, control the flow rate at 0.1 mL / min, and extrude the spinning through a 23G spinneret (inner diameter 0.42 mm) facing the surface of the ternary system coagulation bath described in step S1 (temperature controlled at 22°C) at a distance of 5 mm; S4. Thermal reinforcement: Immerse the fibers solidified and formed in step S3 in a 37°C water bath for 5 min; S5. Freezing enhancement: Freeze the fibers obtained in step S4 at -20°C for 2 h and thaw at room temperature for 2 h, and repeat the cycle 3 times; S6. Post-treatment and drying: Wash the fibers treated in step S5 with water 3 times to remove residual small molecules, and freeze-dry at -40°C for 24 h to obtain hydrogel fibers after shaping.

[0044] Example 3 A method for preparing hydrogel fibers, comprising the following steps: S1. Ternary system coagulation bath: The molar ratio of hydrogen bond donor lactic acid to hydrogen bond acceptor zinc gluconate is 3:1, graphene oxide is 1 wt% of the total mass of the hydrogen bond donor and hydrogen bond acceptor, the hydrogen bond donor and hydrogen bond acceptor account for 80 wt% of the ternary system coagulation bath, 5 wt% calcium chloride, and the balance is water. Mix evenly to obtain the ternary system coagulation bath; S2. Spinning solution preparation: Dissolve polyvinyl alcohol-sodium alginate with a mass ratio of 3:1 in water at a concentration of 10 wt%, stir at 80°C for 30 min, and defoam at room temperature for 10 min to obtain the spinning solution; S3. Wet spinning: Place the spinning solution described in step S2 in an injection pump, control the flow rate at 0.1 mL / min, and extrude the spinning solution through a 23G spinneret (inner diameter 0.42 mm) 5 mm away from the surface of the ternary system coagulation bath (temperature controlled at 22°C) described in step S1; S4. Thermal reinforcement: Immerse the fibers formed by coagulation in step S3 in a 37°C water bath for 5 min; S5. Freezing strengthening: Freeze the fibers obtained in step S4 at -20°C for 2 h and thaw at room temperature for 2 h, and repeat the cycle 3 times; S6. Post-treatment and drying: Wash the fibers treated in step S5 3 times with water to remove residual small molecules, and freeze-dry at -40°C for 24 h to obtain hydrogel fibers after shaping.

[0045] Example 4 A method for preparing hydrogel fibers, comprising the following steps: S1. Ternary system coagulation bath: The molar ratio of hydrogen bond donor lactic acid to hydrogen bond acceptor zinc gluconate is 3:1, graphene oxide is 2 wt% of the total mass of the hydrogen bond donor and hydrogen bond acceptor, the hydrogen bond donor and hydrogen bond acceptor account for 80 wt% of the ternary system coagulation bath, 5 wt% calcium chloride, and the balance is water. Mix evenly to obtain the ternary system coagulation bath; S2. Spinning solution preparation: Dissolve polyvinyl alcohol-sodium alginate with a mass ratio of 3:1 in water at a concentration of 10 wt%, stir at 80°C for 30 min, and degas at room temperature for 10 min to obtain the spinning solution; S3. Wet spinning: Place the spinning solution described in step S2 in an injection pump, control the flow rate at 0.1 mL / min, and extrude the spinning solution through a 23G spinneret (inner diameter 0.42 mm) 5 mm away from the surface of the ternary system coagulation bath (temperature controlled at 22°C) described in step S1; S4. Thermal reinforcement: Immerse the fibers formed by coagulation in step S3 in a 37°C water bath for 5 min; S5. Freezing strengthening: Freeze the fibers obtained in step S4 at -20°C for 2 h and thaw at room temperature for 2 h, and repeat the cycle 3 times; S6. Post-treatment and drying: Wash the fibers treated in step S5 3 times with water to remove residual small molecules, and freeze-dry at -40°C for 24 h to obtain hydrogel fibers (the physical picture is as Figure 1 )

[0046] Example 5 A method for preparing hydrogel fibers, comprising the following steps: S1. Ternary system coagulation bath: The molar ratio of hydrogen bond donor citric acid to hydrogen bond acceptor zinc gluconate is 2:1, graphene oxide is 1 wt% of the total mass of the hydrogen bond donor and hydrogen bond acceptor, the hydrogen bond donor and hydrogen bond acceptor account for 80 wt% of the ternary system coagulation bath, 5 wt% calcium chloride, and the balance is water. Mix them evenly to obtain the ternary system coagulation bath; S2. Spinning solution preparation: Dissolve polyvinyl alcohol - sodium alginate with a mass ratio of 3:1 in water at a concentration of 10 wt%, stir at 80 °C for 30 min, and degas at room temperature for 10 min to obtain the spinning solution; S3. Wet spinning: Place the spinning solution described in step S2 in an injection pump, control the flow rate at 0.1 mL / min, and extrude the spinning through a 23G spinneret (inner diameter 0.42 mm) aiming at the surface of the ternary system coagulation bath described in step S1 (temperature controlled at 22 °C) with a distance of 5 mm; S4. Thermal reinforcement: Immerse the fibers formed by solidification in step S3 in a 37 °C water bath for 5 min; S5. Freezing enhancement: Freeze the fibers obtained in step S4 at -20 °C for 2 h and thaw at room temperature for 2 h, and repeat the cycle 3 times; S6. Post-treatment and drying: Wash the fibers treated in step S5 three times with water to remove residual small molecules, and freeze-dry at -40 °C for 24 h to shape and obtain the hydrogel fibers.

[0047] Example 6 A preparation method of hydrogel fibers, comprising the following steps: S1. Ternary system coagulation bath: The molar ratio of hydrogen bond donor citric acid to hydrogen bond acceptor zinc citrate is 2:1, graphene oxide is 1 wt% of the total mass of the hydrogen bond donor and hydrogen bond acceptor, the hydrogen bond donor and hydrogen bond acceptor account for 80 wt% of the ternary system coagulation bath, 5 wt% calcium chloride, and the balance is water. Mix them evenly to obtain the ternary system coagulation bath; S2. Spinning solution preparation: Dissolve polyvinyl alcohol - sodium alginate with a mass ratio of 3:1 in water at a concentration of 10 wt%, stir at 80 °C for 30 min, and degas at room temperature for 10 min to obtain the spinning solution; S3. Wet spinning: Place the spinning solution described in step S2 in an injection pump, control the flow rate at 0.1 mL / min, and extrude the spinning through a 23G spinneret (inner diameter 0.42 mm) aiming at the surface of the ternary system coagulation bath described in step S1 (temperature controlled at 22 °C) with a distance of 5 mm; S4. Thermal reinforcement: Immerse the fibers formed by solidification in step S3 in a 37 °C water bath for 5 min; S5. Freezing enhancement: Freeze the fibers obtained in step S4 at -20 °C for 2 h and thaw at room temperature for 2 h, and repeat the cycle 3 times; S6. Post-treatment and drying: Wash the fibers treated in step S5 three times with water to remove residual small molecules, and freeze-dry them at -40 °C for 24 h to obtain hydrogel fibers in a fixed shape.

[0048] Example 7 A method for preparing hydrogel fibers, comprising the following steps: S1. Ternary system coagulation bath: The molar ratio of hydrogen bond donor lactic acid to hydrogen bond acceptor zinc gluconate is 2:1, graphene oxide is 1 wt% of the total mass of the hydrogen bond donor and hydrogen bond acceptor, the hydrogen bond donor and hydrogen bond acceptor account for 80 wt% of the ternary system coagulation bath, and the balance is water. Mix evenly to obtain the ternary system coagulation bath; S2. Spinning solution preparation: Dissolve polyvinyl alcohol in water at a concentration of 10 wt%, stir at 80 °C for 30 min, and degas at room temperature for 10 min to obtain the spinning solution; S3. Wet spinning: Place the spinning solution described in step S2 in an injection pump, control the flow rate at 0.1 mL / min, and align the 23G spinneret (inner diameter 0.42 mm) with the surface of the ternary system coagulation bath described in step S1 (temperature controlled at 22 °C), and extrude the spinning at a distance of 5 mm; S4. Thermal reinforcement: Immerse the fibers formed by coagulation in step S3 in a 37 °C water bath for 5 min; S5. Freezing enhancement: Freeze the fibers obtained in step S4 at -20 °C for 2 h and thaw at room temperature for 2 h, and repeat the cycle 3 times; S6. Post-treatment and drying: Wash the fibers treated in step S5 three times with water to remove residual small molecules, and freeze-dry them at -40 °C for 24 h to obtain hydrogel fibers in a fixed shape.

[0049] Comparative Example 1 A method for preparing hydrogel fibers, comprising the following steps: S1. Coagulation bath: The molar ratio of hydrogen bond donor glycerol to hydrogen bond acceptor choline chloride is 1:1, the hydrogen bond donor and hydrogen bond acceptor account for 80 wt% of the coagulation bath, 5 wt% calcium chloride, and the balance is water. Mix evenly to obtain the coagulation bath; S2. Spinning solution preparation: Spinning solution preparation: Dissolve polyvinyl alcohol-sodium alginate with a mass ratio of 3:1 in water at a concentration of 10 wt%, stir at 80 °C for 30 min, and degas at room temperature for 10 min to obtain the spinning solution; S3. Wet spinning: Place the spinning solution described in step S2 in an injection pump, control the flow rate at 0.1 mL / min, and align the 23G spinneret (inner diameter 0.42 mm) with the surface of the coagulation bath described in step S1 (temperature controlled at 22 °C), and extrude the spinning at a distance of 5 mm; S4. Thermal reinforcement: Immerse the fibers formed by coagulation in step S3 in a 37 °C water bath for 5 min; S5. Freezing Strengthening: Freeze the fibers obtained in step S4 at -20°C for 2 h, thaw at room temperature for 2 h, and repeat the cycle 3 times; S6. Post-treatment and Drying: Wash the fibers treated in step S5 with water 3 times to remove residual small molecules, and then freeze-dry at -40°C for 24 h to obtain the hydrogel fibers in a fixed shape.

[0050] Comparative Example 2 A method for preparing hydrogel fibers, comprising the following steps: S1. Coagulation Bath: The molar ratio of the hydrogen bond donor glycerol to the hydrogen bond acceptor choline chloride is 1:1, graphene oxide is 1 wt% of the total mass of the hydrogen bond donor and the hydrogen bond acceptor, the hydrogen bond donor and the hydrogen bond acceptor account for 80 wt% of the coagulation bath, 5 wt% calcium chloride, and the balance is water. Mix evenly to obtain the coagulation bath; S2. Spinning Solution Preparation: Dissolve polyvinyl alcohol-sodium alginate with a mass ratio of 3:1 in water at a concentration of 10 wt%, stir at 80°C for 30 min, and degas at room temperature for 10 min to obtain the spinning solution; S3. Wet Spinning: Place the spinning solution described in step S2 in an injection pump, control the flow rate at 0.1 mL / min, and extrude the spinning solution through a 23G spinneret (inner diameter 0.42 mm) at a distance of 5 mm from the surface of the coagulation bath described in step S1 (temperature controlled at 22°C); S4. Thermal Reinforcement: Immerse the fibers formed by coagulation in step S3 in a 37°C water bath for 5 min; S5. Freezing Strengthening: Freeze the fibers obtained in step S4 at -20°C for 2 h, thaw at room temperature for 2 h, and repeat the cycle 3 times; S6. Post-treatment and Drying: Wash the fibers treated in step S5 with water 3 times to remove residual small molecules, and then freeze-dry at -40°C for 24 h to obtain the hydrogel fibers in a fixed shape.

[0051] Performance Testing 1. Testing Method (1) Morphology Characterization Test Use a scanning electron microscope (SEM, Hitachi, SU 5000) to observe the surface microstructure of the hydrogel fibers. First, cut the fibers into uniform small segments of 2 mm, and at the same time, fix the fiber segments on the stage with conductive glue. After sputtering with gold, operate the scanning electron microscope to observe the appearance of the sample (see details in Figure 2 and Figure 3 ).

[0052] (2) Mechanical Property Test The mechanical properties of the hydrogel fibers were tested using an electronic universal testing machine (CMT610, MTS Industrial Systems (China) Co., Ltd.). The diameter of the hydrogel fibers was measured using a vernier caliper. The length of the hydrogel samples was 5 cm, and the testing speed was 80 mm / min. A cyclic tensile experiment was conducted on the hydrogel fibers, and the elongation at break and breaking strength were recorded. Each type of hydrogel fiber was measured three times and the average value was taken.

[0053] (3)Conductivity testing A 1-cm long hydrogel fiber was taken, and the resistance of the hydrogel fiber was measured using an electrochemical workstation in the frequency range of 10 0 -10 5 Hz. The conductivity was calculated according to σ = L / RS; where: L is the length of the sample, in cm; R is the measured resistance value, in Ω; S represents the effective cross-sectional area of the hydrogel fiber, in cm 2 .

[0054] 2. Test results The test results of the hydrogel fibers of the above-mentioned examples and comparative examples are shown in Table 1 and Figures 1 - 3 as follows; Figure 2 in which (a) - (f) respectively correspond to the scanning electron microscope images of the hydrogel fibers prepared in Examples 1 - 6; Figure 3 in which (a) and (b) are respectively the scanning electron microscope images of the hydrogel fibers prepared in Comparative Example 1 and Comparative Example 2.

[0055] Table 1 Test results of each example and comparative example

[0056] As can be seen from Table 1, the hydrogel fibers prepared using the coagulation bath described in the present invention have good mechanical properties and conductivity. Specifically, the breaking strength of the prepared hydrogel fibers is not less than 0.4 MPa, the elongation at break is not less than 190%, and the conductivity is not less than 2 S / m.

[0057] As can be seen from Examples 1 - 3, as the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor in the coagulation bath increases, the mechanical properties and conductivity of the prepared hydrogel fibers gradually increase.

[0058] As can be seen from Comparative Examples 1 and 2, if a traditional deep eutectic solvent or an enhancer is added to the traditional deep eutectic solvent, the conductivity and mechanical properties of the prepared hydrogel fibers are significantly worse than those of the examples.

[0059] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A ternary system coagulation bath, characterized in that, It includes a hydrogen bond donor and a hydrogen bond acceptor with a molar ratio of not less than 1:1, and a reinforcing agent accounting for 0.5 - 2 wt% of the total mass of the hydrogen bond donor and the hydrogen bond acceptor; the total content of the hydrogen bond donor and the hydrogen bond acceptor accounts for at least 70 wt% of the ternary system coagulation bath; the balance is water; Among them, the hydrogen bond donor is an organic small molecule containing Lewis acidic sites; the hydrogen bond acceptor is a metal-organic complex containing Lewis basic sites; the reinforcing agent is one or more of graphene oxide, carbon nanotubes or poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid).

2. The ternary system coagulation bath according to claim 1, characterized in that, The hydrogen bond donor is one or more of levulinic acid, lactic acid, malic acid or citric acid.

3. The ternary system coagulation bath according to claim 1, wherein The hydrogen bond acceptor is one or more of zinc gluconate, calcium gluconate, magnesium gluconate, calcium lactate or zinc citrate.

4. The ternary system coagulation bath according to claim 1, wherein The reinforcing agent is graphene oxide.

5. The ternary system coagulation bath according to claim 1, wherein The total content of the hydrogen bond donor and the hydrogen bond acceptor accounts for 70 - 85 wt% of the ternary system coagulation bath.

6. The ternary system coagulation bath according to claim 1, wherein, The molar ratio of the hydrogen bond donor to the hydrogen bond acceptor is 1:1 - 3:

1.

7. The ternary system coagulation bath according to claim 1, characterized in that, The ternary system coagulation bath further includes calcium chloride accounting for 3 - 8 wt% of the ternary system coagulation bath.

8. A method for preparing hydrogel fibers, characterized in that, It includes the following steps: It is obtained by extruding the spinning solution into the ternary system coagulation bath according to any one of claims 1 - 7, and then successively through thermal strengthening, freeze strengthening and drying.

9. The preparation method according to claim 8, wherein The spinning solution is one or more of an aqueous solution of polyvinyl alcohol, an aqueous solution of polyvinyl alcohol - sodium alginate or an aqueous solution of polyvinyl alcohol - nanocellulose; the temperature of the ternary system coagulation bath is 20 - 25 °C; the temperature of the thermal strengthening is 37 - 60 °C; the freeze strengthening specifically is freezing at -20 °C for 2 h, thawing at room temperature for 2 h, and circulating 2 - 4 times.

10. A hydrogel fiber, characterized in that, It is prepared by using the preparation method according to claim 8 or 9.

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