High-toughness and high-conductivity supramolecular hydrogel fiber and preparation method thereof

Abstract

The invention relates to a high-toughness and high-conductivity supramolecular hydrogel fiber and a preparation method thereof.The preparation method comprises the steps that sodium alginate with good biocompatibility, polyvinyl alcohol, aniline and m-aminophenylboronic acid are dissolved in water to serve as a spinning solution; coagulating ammonium persulfate and calcium chloride; and extruding the spinning solution into a coagulating bath through a syringe needle, and forming the high-performance supramolecular hydrogel fiber in combination with a wet spinning process and a supramolecular self-assembly strategy. The supramolecular hydrogel fiber prepared by the invention has the characteristics of continuity and controllable diameter, and has high conductivity, excellent stretchability and stable sensing performance.

Description

Technical Field

[0001] The invention belongs to the field of preparation of supramolecular hydrogel fibers, and particularly relates to a high-toughness, high-conductivity supramolecular hydrogel fiber and a preparation method thereof. Background Art

[0002] In recent years, flexible electronics have been widely used in wearable health monitoring, human-computer interaction, and other fields. They can be used in scenarios such as real-time physiological signal detection, motion posture recognition, and flexible energy storage devices. However, when used for in vivo or on-body monitoring, traditional flexible electronic materials have a significant impact on monitoring accuracy and user experience due to mechanical properties mismatch with biological tissue and insufficient electrical signal stability. Therefore, there is a need for a material that combines good biocompatibility, high mechanical flexibility, and stable electrical signal transmission performance to adapt to the complex biological environment and achieve precise signal transmission.

[0003] As a new functional material, hydrogel fibers not only possess the inherent soft and wet properties of hydrogels and excellent biocompatibility, but also have the high aspect ratio and weavability of fibers, showing unique advantages in the field of flexible sensing. However, existing preparation methods mostly use template methods or physical coating, which restricts the length and diameter of such materials to the template, making it difficult to achieve large-scale continuous preparation. In addition, the interfacial bonding between the electroactive substance and the fiber substrate is poor, resulting in insufficient electrochemical stability and mechanical properties, limiting its further application in the field of flexible electronics. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a high-toughness, high-conductivity supramolecular hydrogel fiber and a preparation method thereof, construct a supramolecular conductive hydrogel fiber with an interlocking double-crosslinked network structure, overcome the performance limitations of traditional materials and the difficulties in continuous spinning and poor conductivity. In the present invention, sodium alginate and polyvinyl alcohol, aniline and m-aminophenylboronic acid with good biocompatibility are dissolved in water as a spinning solution; a coagulation bath of ammonium persulfate and calcium chloride is used; the spinning solution is squeezed into the coagulation bath through a syringe needle, and a high-performance supramolecular hydrogel fiber is formed by combining a wet spinning process and a supramolecular self-assembly strategy.

[0005] A continuous preparation method of supramolecular conductive hydrogel fibers according to the present invention is characterized by comprising the following steps:

[0006] (1) dissolving polyvinyl alcohol, sodium alginate, aniline and m-aminophenylboric acid in water to form a spinning solution;

[0007] (2) dissolving ammonium persulfate and calcium chloride in a mixed solution of dimethyl sulfoxide and deionized water, respectively, to form a coagulation bath;

[0008] (3) The spinning solution is squeezed out through a needle into a coagulation bath, and the spinning is carried out in one step by wet spinning. The sodium alginate and the Ca in the coagulation bath are mixed. 2+ The first layer of ionic crosslinking is self-assembled through electrostatic interactions. Aniline and m-aminophenylboronic acid copolymerize to form polyaniline polymer chains with boronic acid groups, which then form a second layer of dynamic borate ester covalent crosslinking with the hydroxyl groups of polyvinyl alcohol. Simultaneously, hydrogen bonding interactions occur between polyaniline, polyvinyl alcohol, and sodium alginate, ultimately forming nascent hydrogel fibers with a three-dimensional porous structure and multiple synergistic interactions. The supramolecular hydrogel fibers are then collected by winding.

[0009] The preferred embodiment of the above preparation method is as follows:

[0010] In the spinning solution in step (1), the mass fraction of polyvinyl alcohol is about 10%, the mass fraction of sodium alginate is about 4%, the concentration of aniline is about 0.3-1.2M, the concentration of m-aminophenylboronic acid is about 7% of the aniline concentration, and the remainder is deionized water.

[0011] The aniline concentration in the spinning solution in step (1) is 0.3-1.2M.

[0012] The composition of the coagulation bath in step (2) is: calcium chloride mass fraction of about 5%, ammonium persulfate mass fraction of about 18%, and dimethyl sulfoxide:deionized water ratio of 3:2.

[0013] The diameter of the needle used in the wet spinning process in step (2) is 16-24G.

[0014] In the step (2), the extrusion is performed by using a propulsion pump to extrude the spinning solution through a syringe needle; the extrusion rate is 0.5 mL / min.

[0015] The polymerization time of aniline in step (2) is 5min, 10min, 30min, 60min and 120min. The supramolecular hydrogel fiber formed in step (3) has an interlocking double cross-linked network structure, including sodium alginate and Ca 2+ The ionic cross-linked network formed and the dynamic borate ester bond covalent cross-linked network formed by the boronic acid groups of polyaniline and the hydroxyl groups of polyvinyl alcohol.

[0016] The present invention discloses a supramolecular conductive hydrogel fiber prepared by the method.

[0017] The present invention also provides a device for the continuous preparation of supramolecular conductive hydrogel fibers, wherein the device comprises, in sequence: a feeding zone, a fiber forming zone, and a collecting zone, wherein the feeding zone is provided with an injection pump for providing a stable driving force to transport the spinning solution; the fiber forming zone comprises a syringe needle and a coagulation bath for extruding the spinning solution into the coagulation bath for in-situ polymerization; the collecting zone is provided with a collecting device for collecting the formed conductive supramolecular hydrogel fibers; wherein there is a certain temperature difference between the spinning solution and the coagulation bath to optimize the wet spinning effect.

[0018] Beneficial effects

[0019] To address the shortcomings of traditional conductive fiber preparation, which include cumbersome processes and poor interfacial compatibility and weak bonding between the electroactive material and the fiber substrate, resulting in difficulty adapting the device to complex surfaces and mechanical deformations, this present invention achieves a one-step, continuous formation of supramolecular hydrogel fibers by synergizing wet spinning technology with supramolecular self-assembly principles. This process simultaneously completes ionic network crosslinking and in-situ polymerization of polyaniline in a coagulation bath, eliminating the need for an additional loading step. The spinning speed is precisely controlled by a syringe pump, addressing the low efficiency and instability of traditional preparation methods while simultaneously improving the interfacial bonding strength of the material.

[0020] The preparation method of the present invention is a high-toughness, high-conductivity supramolecular hydrogel fiber and its preparation method. Sodium alginate, polyvinyl alcohol, m-aminophenylboronic acid and aniline with good biocompatibility are dissolved in water to make a spinning solution. The spinning solution is squeezed into a coagulation bath containing ammonium persulfate and calcium chloride through a syringe needle. Finally, a high-performance supramolecular conductive hydrogel fiber is formed by combining wet spinning technology and supramolecular self-assembly strategy. In order to solve the problem that most hydrogel fibers have poor mechanical properties (limited breaking strain and insufficient toughness), the present invention constructs an interlocking double cross-linked network structure, including sodium alginate and calcium chloride. 2+ The formed ionic cross-linked network and the dynamic borate bond covalent cross-linked network formed by polyaniline with boric acid groups and the hydroxyl groups of polyvinyl alcohol are interwoven and reinforced, solving the problem that traditional hydrogel fibers are difficult to balance mechanical properties and structural integrity. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the preparation of supramolecular hydrogel fibers constructed by combining wet spinning and supramolecular self-assembly strategy in Example 1;

[0022] Figure 2 Schematic diagram of the cross-linking process of supramolecular hydrogel fibers in Example 1;

[0023] Figure 3 This is a scanning electron micrograph of the supramolecular conductive hydrogel fiber in Example 1;

[0024] Figure 4The stress-strain curves of the supramolecular conductive hydrogel fiber in Example 1 at different polymerization times;

[0025] Figure 5 The stress-strain curves of the supramolecular conductive hydrogel fiber in Example 1 at different needle sizes;

[0026] Figure 6 This is a graph showing the change in the strain coefficient of the supramolecular conductive hydrogel fiber in Example 1;

[0027] Figure 7 This is a graph showing the response time of the supramolecular conductive hydrogel fiber in Example 1; DETAILED DESCRIPTION

[0028] The present invention will be further described below with reference to specific examples. It should be understood that these examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. Furthermore, it should be understood that after reading the teachings of the present invention, those skilled in the art may make various changes or modifications to the present invention, and that these equivalent forms also fall within the scope defined by the appended claims of this application. The apparatus used in the examples includes: a feed zone, a fiber formation zone, and a collection zone; the feed zone is provided with a syringe pump for providing a stable driving force; the fiber formation zone includes a container containing a coagulation bath and a needle inserted into the coagulation bath; and the collection zone is provided with a winding device for drawing and collecting the fibers. The materials used in the examples are: polyvinyl alcohol (1750), purchased from Sinopharm Chemical Reagent Co., Ltd.; sodium tetraborate decahydrate, ammonium persulfate, aniline, and sodium alginate, purchased from Shanghai MacLean Biochemical Technology Co., Ltd.; dimethyl sulfoxide, purchased from Tianjin Fuyu Fine Chemicals Co., Ltd.; and m-aminophenylborate hydrochloride, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; all other reagents used in the experiments were of analytical grade and used directly without further purification.

[0029] Example 1

[0030] At room temperature, 0.495g of polyvinyl alcohol (PVA) was placed in 2.835g of deionized water and stirred at 60°C for 30 minutes until swollen. The mixture was then heated to 95°C and stirred for 120 minutes to prepare a 15% PVA solution. 0.06g of m-aminophenyl boronate hydrochloride was dissolved in 0.833mL of 6M hydrochloric acid and sonicated for 10 minutes. The PVA solution was then added and stirred until homogeneous. 0.5g of sodium alginate, 0.372mL of deionized water, and 1.0M of aniline were then added in sequence. After stirring, the mixture was sonicated for 10 minutes to remove bubbles to obtain the spinning solution. 68.4mL of deionized water was added to a beaker, followed by 29.3g of ammonium persulfate, 48mL of dimethyl sulfoxide, and 8.11g of calcium chloride, and stirred until completely dissolved. During wet spinning, the spinning solution was extruded into the coagulation bath through a 20G syringe needle at a flow rate of 0.5mL / min. The temperature difference between the spinning solution and the coagulation bath was controlled at 5°C. After in situ polymerization for 30 minutes, the fiber was collected to obtain a high-toughness, high-conductivity supramolecular hydrogel fiber with a diameter of about 580μm, a breaking strain of 1200%, a tensile strength of 2MPa, a conductivity of 1.38S / m, high sensing sensitivity (GF of 5.58), a response time of 0.2 seconds and good stability.

[0031] Figure 1 shows a schematic diagram of a supramolecular conductive hydrogel fiber continuous spinning system based on wet spinning and supramolecular self-assembly strategies. As can be seen from the figure, the system primarily consists of a feed zone, a fiber formation zone, and a collection zone. The syringe pump in the feed zone provides a stable force, transforming the static solution generated in the fiber formation zone into a lubricated microfluidic layer to ensure smooth spinning of the supramolecular hydrogel fibers. Prior to collection, the supramolecular hydrogel fibers undergo an increase in polymerization degree in the fiber reinforcement zone. Finally, the fibers are collected in the collection zone and can be further woven into hydrogel fabrics. The entire system enables the continuous preparation of supramolecular hydrogel fibers.

[0032] Schematic diagram of the cross-linking process of supramolecular hydrogel fibers, as shown in Figure 2 As shown in the figure, sodium alginate and Ca in the coagulation bath 2+ The ionic crosslinking network is formed through electrostatic self-assembly, and the dynamic borate ester covalent crosslinking network is formed through the hydroxyl groups of polyaniline with boric acid groups and polyvinyl alcohol. At the same time, hydrogen bonding interactions occur between polyaniline, polyvinyl alcohol and sodium alginate molecular chains, ultimately forming a supramolecular hydrogel fiber with a three-dimensional porous structure.

[0033] SEM images of supramolecular hydrogel fibers Figure 3 As shown in the figure, the fiber morphology is regular and the diameter of the supramolecular hydrogel fiber prepared by this method is about 580 μm.

[0034] Stress-strain curves of supramolecular hydrogel fibers at different polymerization times, e.g. Figure 4As shown in the figure, when the polymerization time in the coagulation bath is 30 minutes, the stress-strain curve of the fiber is at a higher position, corresponding to the best mechanical properties, showing better tensile strength and elongation at break. This is because the molecular chains of polyvinyl alcohol and polyaniline are fully cross-linked during this time, the crystallinity is increased, and impurities are completely removed, forming a more uniform and stable structure.

[0035] Stress-strain curves of supramolecular hydrogel fibers at different needle sizes, e.g. Figure 5 As shown in the figure, when using a 20G needle, the overall curve is higher than the curves corresponding to other needle sizes. The stress of the fiber increases more reasonably with strain, showing the highest elongation at break (1200%) and tensile strength (2MPa). However, needle sizes that are too large or too small will cause large fluctuations in the curve and deteriorate the mechanical properties, indicating that the 20G needle is an ideal choice for preparing this fiber.

[0036] The graph of the change of the strain coefficient of supramolecular hydrogel fibers, such as Figure 6 As shown in the figure, the fiber exhibits excellent sensing sensitivity across different strain ranges. When the strain is less than 100%, the gauge factor (GF) reaches 2.48; within the strain range of 100% to 200%, the GF increases to 3.92; and when the strain exceeds 200%, the GF reaches as high as 5.58, far exceeding the sensitivity of existing strain sensors on the market.

[0037] Supramolecular hydrogel fiber response time test diagram, such as Figure 7 As shown in the figure, the resistance of the fiber changes rapidly and stably during rapid stretching and rebounding, with a response time of only 0.2s, demonstrating excellent dynamic response performance.

[0038] Example 2

[0039] At room temperature, 0.495g of polyvinyl alcohol (PVA) was placed in 2.835g of deionized water and stirred at 60°C for 30 minutes to fully swell the solution. The solution was then heated to 95°C and stirred continuously for 120 minutes to prepare a 15% PVA solution. Separately, 0.06g of m-aminophenyl boronate hydrochloride was dissolved in 0.833mL of 6M hydrochloric acid and ultrasonicated for 10 minutes. The PVA solution was then added and stirred until uniformly mixed. 0.5g of sodium alginate, 0.372mL of deionized water, and 0.3M of aniline were then added, stirred, and ultrasonicated for 10 minutes to remove bubbles. This yielded the spinning solution. To prepare the coagulation bath, 68.4mL of deionized water was added to a beaker, followed by 29.3g of ammonium persulfate, 48mL of dimethyl sulfoxide, and 8.11g of calcium chloride, and stirred until completely dissolved. During wet spinning, the spinning solution was squeezed into the coagulation bath through a 20G syringe needle at a flow rate of 0.5mL / min. The temperature difference between the spinning solution and the coagulation bath was controlled at 5°C. After in-situ polymerization for 30 minutes, the fibers were collected. The resulting supramolecular hydrogel fibers had a diameter of about 580μm, possessed certain mechanical properties and an electrical conductivity of about 1.38S / m, and an area specific capacitance of 320mF / cm 2 , and the redox peak of the CV curve is weak.

[0040] Example 3

[0041] 0.495 g of polyvinyl alcohol was weighed at room temperature and placed in 2.835 g of deionized water. The solution was stirred at a constant speed at 60 ° C for 30 min to allow the polyvinyl alcohol to swell. The temperature was then raised to 95 ° C and stirred for 120 min to obtain 3.33 g of 15% polyvinyl alcohol solution. 0.06 g of m-aminophenyl boric acid hydrochloride was dissolved in 0.833 mL of water. In 6M hydrochloric acid, after ultrasonic treatment for 10 minutes, the above-mentioned polyvinyl alcohol solution was added and stirred and heated until mixed uniformly. Then, 0.3g sodium alginate, 0.372mL deionized water and 0.372mL 1.0M aniline were added in sequence. After sufficient reaction, internal bubbles were eliminated by ultrasonication for 10 minutes to obtain PBPH spinning solution; then a coagulation bath was prepared, 68.4mL deionized water, 29.3g ammonium persulfate, 48mL dimethyl sulfoxide and 8.11g calcium chloride were added to a beaker and stirred until completely dissolved. The spinning solution was extruded through a 20G syringe needle at a flow rate of 0.5mL / min and injected into the coagulation bath for in situ polymerization (a certain temperature difference between the spinning solution and the coagulation bath was maintained to optimize the spinning effect). After 30 minutes, the fiber was recovered by a collection device to obtain a supramolecular hydrogel fiber with a diameter of about 0.28mm; compared with the fiber prepared with the original concentration (0.5g SA), the mechanical properties and electrical conductivity were slightly adjusted due to the change in crosslinking density. The conductivity of the prepared fiber was tested on an electrochemical workstation and was found to be 1.25 S / m. Its mechanical properties were tested using a universal tensile machine at a tensile rate of 20 mm / min and a gauge length of 5 mm, showing a tensile strength of ~1.8 MPa and a breaking strain of ~1050%.

Claims

1. A continuous preparation method of high-toughness and high-conductivity supramolecular hydrogel fibers, characterized in that: The steps include: (1) dissolving polyvinyl alcohol, sodium alginate, aniline and m-aminophenylboric acid in water to form a spinning solution; (2) dissolving ammonium persulfate and calcium chloride in a mixed solution of dimethyl sulfoxide and deionized water, respectively, to form a coagulation bath; (3) The spinning solution is squeezed out through a needle into a coagulation bath, and the spinning is carried out in one step by wet spinning. The sodium alginate and the Ca in the coagulation bath are mixed. 2+ The first layer of ionic crosslinking is self-assembled through electrostatic interactions. Aniline and m-aminophenylboronic acid copolymerize to form polyaniline polymer chains with boronic acid groups, which then form a second layer of dynamic borate ester covalent crosslinking with the hydroxyl groups of polyvinyl alcohol. Simultaneously, hydrogen bonding interactions occur between polyaniline, polyvinyl alcohol, and sodium alginate, ultimately forming nascent hydrogel fibers with a three-dimensional porous structure and multiple synergistic interactions. The supramolecular hydrogel fibers are then collected by winding.

2. The preparation method according to claim 1, characterized in that In the spinning solution in step (1), the mass fraction of polyvinyl alcohol is about 10%, the mass fraction of sodium alginate is about 4%, the concentration of aniline is about 0.3-1.2M, the concentration of m-aminophenylboronic acid is about 7% of the aniline concentration, and the remainder is deionized water.

3. The preparation method according to claim 1, characterized in that: The aniline concentration in the spinning solution in step (1) is 0.3-1.2M.

4. The preparation method according to claim 1, characterized in that The composition of the coagulation bath in step (2) is as follows: calcium chloride with a mass fraction of 5%, ammonium persulfate with a mass fraction of 18%, and a dimethyl sulfoxide:deionized water ratio of 3:

2.

5. The preparation method according to claim 1, characterized in that: The diameter of the needle used in the wet spinning process in step (2) is 16-24G.

6. The preparation method according to claim 1, characterized in that: In step (2), the extrusion is performed by using a propulsion pump to extrude the spinning solution through a syringe needle; The extrusion rate is 0.5 mL / min.

7. The preparation method according to claim 1, characterized in that The aniline polymerization time in step (2) is 5 min, 10 min, 30 min, 60 min, and 120 min.

8. The preparation method according to claim 1, characterized in that The supramolecular hydrogel fiber formed in step (3) has an interlocking double cross-linked network structure, comprising sodium alginate and Ca 2+ The ionic cross-linked network formed and the dynamic borate ester bond covalent cross-linked network formed by the boronic acid groups of PANI and the hydroxyl groups of polyvinyl alcohol.

9. A supramolecular hydrogel fiber prepared by the method according to claim 1.

10. A device for continuously preparing the supramolecular conductive hydrogel fiber according to claim 1, wherein the device comprises: The feeding area, the fiber forming area, and the collecting area are provided with an injection pump for providing a stable driving force to transport the spinning solution; the fiber forming area includes a syringe needle and a coagulation bath for extruding the spinning solution into the coagulation bath for in-situ polymerization; the collecting area is provided with a collecting device for collecting the formed supramolecular conductive hydrogel fibers; a certain temperature difference exists between the spinning solution and the coagulation bath to optimize the wet spinning effect.

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