Preparation method of composite conductive hydrogel electrode material
By constructing an interpenetrating network structure of sodium alginate, polyacrylamide, copolyacrylic acid and multi-wall carbon nanotubes, and introducing polyaniline into the hydrogel, the problem of insufficient mechanical and electrochemical properties of conductive polymer hydrogels is solved, and a high-performance composite conductive hydrogel electrode material is achieved.
Patent Information
- Application Number
- CN202510415804.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-03
- Publication Date
- 2025-06-13
AI Technical Summary
The existing conductive polymer hydrogels have shortcomings in mechanical properties and electrochemical properties, and it is difficult to meet the high-performance needs of flexible electronic devices.
By combining sodium alginate, polyacrylamide, copolyacrylic acid and multi-wall carbon nanotubes, an interpenetrating network structure is constructed, and polyaniline and oxidizing agent are introduced into the hydrogel for in-situ polymerization, a composite conductive hydrogel electrode material is prepared.
It realizes the high tensile strength, elongation of break and conductivity of conductive hydrogels, significantly improving its mechanical properties and electrochemical properties, and is suitable for flexible electronic equipment.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention belongs to the field of flexible electronic materials, relates to conductive functional polymer hydrogels, and specifically relates to a preparation method of a composite conductive hydrogel electrode material. Background Art
[0002] With the progress of technology, the development of the times, and the improvement of living standards, intelligent electronic devices are closely related to people's lives, and at the same time, the performance of various aspects of electronic devices has also become a hot topic of concern. Among these electronic devices, flexible supercapacitors stand out. Flexible supercapacitors have the high energy storage effect of batteries while maintaining ultra-high power density and fast charge and discharge characteristics. The core of flexible supercapacitors is the design and preparation of high-performance and easy-to-process flexible electrode materials and electrolyte materials.
[0003] Conductive polymers have the advantages of low cost, high specific capacitance, light weight, high conductivity, etc., and are ideal materials for preparing flexible supercapacitor electrodes. Among them, polyaniline has the advantages of high theoretical specific capacitance, cheap and easily available raw materials, easy synthesis, good environmental stability, high conductivity, strong charge storage ability, etc., and has become one of the most promising active electrode materials. However, conductive polymers are rigid materials and are not suitable for directly being used as flexible electrodes. Therefore, introducing conductive polymers into hydrogels to prepare conductive polymer hydrogels with excellent mechanical properties has attracted great interest.
[0004] Hydrogels have unique three-dimensional network porous structures and good flexibility, deformability, etc., and are commonly used flexible substrates for preparing flexible electrode materials. However, due to the uneven internal cross-linking density of molecules, natural hydrogels and traditional hydrogels have deficiencies such as poor mechanical strength and stability, and being brittle, which limits the application of hydrogels in biomedical, flexible energy storage devices, etc. Interpenetrating network hydrogels have two interpenetrating and entangled network structures. Under the action of external forces, the two networks will undergo relative displacement, thereby quickly and efficiently dissipating energy and improving mechanical properties. Therefore, introducing conductive polymers into interpenetrating network hydrogels is expected to prepare conductive hydrogels with excellent mechanical properties and good electrochemical properties. Summary of the Invention
[0005] The purpose of the present invention is to provide a preparation method of a composite conductive hydrogel electrode material aiming at the deficiencies of the prior art, and the obtained conductive hydrogel has good flexibility, excellent mechanical properties, and good electrochemical properties.
[0006] To achieve the above purpose, the present invention adopts the following technical solutions: A preparation method of a composite conductive hydrogel electrode material, and its preparation steps are as follows: (1) Prepare a dispersion liquid of sodium alginate, acrylamide, acrylic acid, and multi-walled carbon nanotubes; (2) Add a crosslinking agent and an initiator to the dispersion obtained in step (1), and polymerize to prepare a sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube composite hydrogel; (3) Immerse the composite hydrogel prepared in step (2) in a calcium chloride solution for a certain period of time to cause a crosslinking reaction, and prepare a sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube interpenetrating network hydrogel; (4) Immerse the interpenetrating network hydrogel prepared in step (3) in deionized water for swelling for a certain period of time, then place the swollen gel in an aniline solution for low-temperature pre-infiltration for a certain period of time, and then add an oxidizing agent and a doping acid for in-situ polymerization reaction to prepare a sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube / polyaniline composite conductive hydrogel electrode material.
[0007] Specifically, in step (1), 0.3 g of sodium alginate, 2.5 g of acrylamide, and 0.5 g of acrylic acid are added to 20 mL of deionized water, stirred and dissolved at room temperature, and then 5 mg of multi-walled carbon nanotubes are added to the mixture, and stirred and dispersed at room temperature for 2 h to obtain a dispersion of sodium alginate, acrylamide, acrylic acid, and multi-walled carbon nanotubes.
[0008] Specifically, in step (2), 3 mL of an aqueous ammonium persulfate solution with a concentration of 0.01 g / mL and 300 μL of an aqueous N,N'-methylenebisacrylamide solution with a concentration of 0.01 g / mL are added to the dispersion of sodium alginate, acrylamide, acrylic acid, and multi-walled carbon nanotubes, stirred at room temperature for 1 h to disperse evenly, then degassed by ultrasonic treatment for 30 min, and then poured into a mold and reacted at 65 °C for 5 h to obtain a sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube composite hydrogel.
[0009] Specifically, in step (3), the sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube composite hydrogel is immersed in a 0.1 mol / L calcium chloride solution for 2 h to cause a crosslinking reaction, and then the surface of the gel is rinsed with deionized water to remove impurities, and a sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube interpenetrating network hydrogel is obtained.
[0010] Step (4) is specifically as follows: Dissolve 0.3887 g of aniline hydrochloride in 30 mL of deionized water, cool the solution to 0 °C, and denote it as Solution I; dissolve 0.4564 g of ammonium persulfate in 2.4 mL of deionized water, add 600 μL of a 50% phytic acid solution, stir evenly, cool the solution to 0 °C, and denote it as Solution II; place the sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube interpenetrating network hydrogel in 250 mL of deionized water and swell it for 48 h, then put the swollen interpenetrating network hydrogel into Solution I and pre-permeate it at 0 °C for 30 min, then add Solution II thereto, after reacting for 48 h, wash the obtained hydrogel with deionized water to obtain a sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube / polyaniline composite conductive hydrogel.
[0011] Using the sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube interpenetrating network hydrogel as a flexible substrate, the gel is toughened by constructing an interpenetrating network structure. Among them, sodium alginate crosslinks with calcium ions to form the first physical crosslinking network, and polyacrylamide copolymerizes with acrylic acid to form the second chemical crosslinking network. The two act synergistically to endow the hydrogel with high tensile strength and high elongation at break, and the mechanical properties are superior to those of a single network hydrogel. Polyaniline is introduced as a conductive polymer into the hydrogel substrate to prepare a composite conductive hydrogel, and at the same time, multi-walled carbon nanotubes are introduced to improve the conductivity of the composite conductive hydrogel. The present invention can effectively regulate the mechanical properties, electrical conductivity and electrochemical properties of the hydrogel by changing the dosages of sodium alginate and multi-walled carbon nanotubes.
[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) Sodium alginate belongs to common biomass materials and has many advantages such as rich sources, biodegradability, and good biocompatibility. The molecular structure of sodium alginate contains a large number of hydroxyl groups and has high chemical activity, and can quickly form a three-dimensional network structure with calcium ions under mild conditions. The present invention utilizes the crosslinking of sodium alginate with calcium ions to form the first physical crosslinking network, and the copolymerization of polyacrylamide with acrylic acid to form the second chemical crosslinking network. The two networks act synergistically to endow the hydrogel with excellent tensile strength and elongation at break, and at the same time, the introduction of calcium ions also has a certain promoting effect on the conductivity of the hydrogel.
[0013] (2) The present invention introduces multi-walled carbon nanotubes with excellent electrical conductivity. Due to its unique graphene sheet structure, one-dimensional quantum confinement effect, high carrier mobility and multi-layer synergistic effect, etc., multi-walled carbon nanotubes exhibit excellent electrical conductivity, and at the same time, they also have the advantages of high strength and good flexibility, which significantly improves the electrical conductivity and mechanical properties of the composite conductive hydrogel.
[0014] (3) The present invention adopts a method of low-temperature pre-permeation of sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube interpenetrating network hydrogel in aniline solution to form a gel network for aniline adsorption inside the hydrogel, and then constructs a reticularly distributed polyaniline conductive network. During the in-situ polymerization process, phytic acid serves both as an acid dopant and as a cross-linking agent to cross-link polyaniline chains, making the conductive network more perfect, thereby improving the electrochemical performance of the composite conductive hydrogel. Description of the Drawings
[0015] Figure 1 It is a comparison chart of the mechanical properties of the sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube interpenetrating network hydrogel prepared in Example 1 and the hydrogels prepared in Comparative Examples 1 and 2.
[0016] Figure 2 It is a comparison chart of the areal specific capacitance of the sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube / polyaniline composite conductive hydrogel prepared in Example 2 and the hydrogels prepared in Comparative Examples 3 and 4.
[0017] Figure 3 It is the cyclic voltammetry (CV) curve of the sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube / polyaniline composite conductive hydrogel prepared in Example 2 at different scanning rates.
[0018] Figure 4 It is a comparison chart of the mechanical properties of the sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube / polyaniline composite conductive hydrogel prepared in Example 2 and the hydrogels prepared in Comparative Examples 5 and 6.
[0019] Figure 5 It is a comparison chart of the conductivity of the sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube / polyaniline composite conductive hydrogel prepared in Example 2 and the hydrogels prepared in Comparative Examples 5 and 6.
[0020] Figure 6 It is a comparison chart of the conductivity of the sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube interpenetrating network hydrogel prepared in Example 1 and the sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube / polyaniline composite conductive hydrogel prepared in Example 2.
[0021] Figure 7 It is the areal specific capacitance of the sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube / polyaniline composite conductive hydrogel prepared in Example 2 at different current densities. Detailed Embodiments
[0022] To make the content of the present invention easier to understand, the technical solutions of the present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited thereto.
[0023] Example 1 (1) Add 0.3 g of sodium alginate, 2.5 g of acrylamide, and 0.5 g of acrylic acid to 20 mL of deionized water, stir and dissolve at room temperature. Subsequently, add 5 mg of multi-walled carbon nanotubes to the mixture, and stir and disperse at room temperature for 2 h to obtain a dispersion of sodium alginate, acrylamide, acrylic acid, and multi-walled carbon nanotubes.
[0024] (2) Add 3 mL of an aqueous ammonium persulfate solution with a concentration of 0.01 g / mL and 300 μL of an aqueous N,N'-methylenebisacrylamide solution with a concentration of 0.01 g / mL to the dispersion of sodium alginate, acrylamide, acrylic acid, and multi-walled carbon nanotubes, stir at room temperature for 1 h to make it evenly dispersed, then ultrasonically degas for 30 min, and then pour it into a mold and react at 65 °C for 5 h to obtain a sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube composite hydrogel.
[0025] (3) Immerse the sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube composite hydrogel in a 0.1 mol / L calcium chloride solution for 2 h to cause a cross-linking reaction. Subsequently, rinse the surface of the gel with deionized water to remove impurities, and obtain a sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube interpenetrating network hydrogel.
[0026] Example 2 (1) This step is the same as step (1) of Example 1 to prepare a dispersion of sodium alginate, acrylamide, acrylic acid, and multi-walled carbon nanotubes.
[0027] (2) This step is the same as step (2) of Example 1 to prepare a sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube composite hydrogel.
[0028] (3) This step is the same as step (3) of Example 1 to prepare a sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube interpenetrating network hydrogel.
[0029] (4) Dissolve 0.3887 g of aniline hydrochloride in 30 mL of deionized water, cool the solution to 0 °C, and label it as Solution I; dissolve 0.4564 g of ammonium persulfate in 2.4 mL of deionized water, add 600 μL of a 50% phytic acid solution by mass, stir evenly, cool the solution to 0 °C, and label it as Solution II; place the sodium alginate / polyacrylamide copolyacrylic acid / multi-walled carbon nanotube interpenetrating network hydrogel in 250 mL of deionized water and swell it for 48 h, then put the swollen interpenetrating network hydrogel into Solution I and pre-permeate it at 0 °C for 30 min, then add Solution II thereto, and after reacting for 48 h, wash the obtained hydrogel with deionized water to obtain a sodium alginate / polyacrylamide copolyacrylic acid / multi-walled carbon nanotube / polyaniline composite conductive hydrogel.
[0030] Comparative Example 1 Add 2.5 g of acrylamide and 0.5 g of acrylic acid to 20 mL of deionized water, stir and dissolve at room temperature, then add 3 mL of an ammonium persulfate aqueous solution with a concentration of 0.01 g / mL and 300 μL of an N,N'-methylenebisacrylamide aqueous solution with a concentration of 0.01 g / mL, stir at room temperature for 1 h to disperse evenly, then ultrasonically degas for 30 min, and then pour it into a mold and react at 65 °C for 5 h to obtain a polyacrylamide copolyacrylic acid hydrogel.
[0031] Comparative Example 2 (1) Add 0.3 g of sodium alginate, 2.5 g of acrylamide, and 0.5 g of acrylic acid to 20 mL of deionized water, stir and dissolve at room temperature, then add 3 mL of an ammonium persulfate aqueous solution with a concentration of 0.01 g / mL and 300 μL of an N,N'-methylenebisacrylamide aqueous solution with a concentration of 0.01 g / mL, stir at room temperature for 1 h to disperse evenly, then ultrasonically degas for 30 min, and then pour it into a mold and react at 65 °C for 5 h to obtain a sodium alginate / polyacrylamide copolyacrylic acid composite hydrogel.
[0032] (2) Immerse the sodium alginate / polyacrylamide copolyacrylic acid composite hydrogel in a 0.1 mol / L calcium chloride solution for 2 h to cause a cross-linking reaction, and then rinse the surface of the hydrogel with deionized water to remove impurities to obtain a sodium alginate / polyacrylamide copolyacrylic acid interpenetrating network hydrogel.
[0033] Comparative Example 3 (1) This step is the same as step (1) of Comparative Example 1 to prepare a polyacrylamide copolyacrylic acid hydrogel.
[0034] (2) Dissolve 0.3887 g of aniline hydrochloride in 30 mL of deionized water, cool the solution to 0 °C, and label it as Solution I; dissolve 0.4564 g of ammonium persulfate in 2.4 mL of deionized water, add 600 μL of 50% phytic acid solution, stir evenly, cool the solution to 0 °C, and label it as Solution II; place the polyacrylamide copolyacrylic acid hydrogel in 250 mL of deionized water and swell it for 48 h. Then, put the swollen polyacrylamide copolyacrylic acid hydrogel into Solution I and pre-permeate it at 0 °C for 30 min. Then, add Solution II to it. After reacting for 48 h, wash the obtained hydrogel with deionized water to obtain a polyacrylamide copolyacrylic acid / polyaniline composite conductive hydrogel.
[0035] Comparative Example 4 (1) This step is the same as step (1) of Comparative Example 2 to prepare a sodium alginate / polyacrylamide copolyacrylic acid composite hydrogel.
[0036] (2) This step is the same as step (2) of Comparative Example 2 to prepare a sodium alginate / polyacrylamide copolyacrylic acid interpenetrating network hydrogel.
[0037] (3) Dissolve 0.3887 g of aniline hydrochloride in 30 mL of deionized water, cool the solution to 0 °C, and label it as Solution I; dissolve 0.4564 g of ammonium persulfate in 2.4 mL of deionized water, add 600 μL of 50% phytic acid solution, stir evenly, cool the solution to 0 °C, and label it as Solution II; place the sodium alginate / polyacrylamide copolyacrylic acid interpenetrating network hydrogel in 250 mL of deionized water and swell it for 48 h. Then, put the swollen sodium alginate / polyacrylamide copolyacrylic acid interpenetrating network hydrogel into Solution I and pre-permeate it at 0 °C for 30 min. Then, add Solution II to it. After reacting for 48 h, wash the obtained hydrogel with deionized water to obtain a sodium alginate / polyacrylamide copolyacrylic acid / polyaniline composite conductive hydrogel.
[0038] Comparative Example 5 (1) Add 0.3 g of sodium alginate, 2.5 g of acrylamide, and 0.5 g of acrylic acid to 20 mL of deionized water, stir and dissolve at room temperature. Subsequently, add 2.5 mg of multi-walled carbon nanotubes to the mixture and stir and disperse at room temperature for 2 h to obtain a dispersion of sodium alginate, acrylamide, acrylic acid, and multi-walled carbon nanotubes.
[0039] (2) This step is the same as step (2) of Example 1 to prepare a sodium alginate / polyacrylamide copolyacrylic acid / multi-walled carbon nanotube composite hydrogel.
[0040] (3) This step is the same as step (3) of Example 1 to prepare a sodium alginate / polyacrylamide copolyacrylic acid / multi-walled carbon nanotube interpenetrating network hydrogel.
[0041] (4) This step is the same as step (4) of Example 1, and a sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube / polyaniline composite conductive hydrogel is prepared.
[0042] Comparative Example 6 (1) Add 0.3 g of sodium alginate, 2.5 g of acrylamide, and 0.5 g of acrylic acid to 20 mL of deionized water, stir and dissolve at room temperature. Subsequently, add 10 mg of multi-walled carbon nanotubes to the mixture and stir and disperse at room temperature for 2 h to obtain a dispersion of sodium alginate, acrylamide, acrylic acid, and multi-walled carbon nanotubes.
[0043] (2) This step is the same as step (2) of Example 1, and a sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube composite hydrogel is prepared.
[0044] (3) This step is the same as step (3) of Example 1, and a sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube interpenetrating network hydrogel is prepared.
[0045] (4) This step is the same as step (4) of Example 1, and a sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube / polyaniline composite conductive hydrogel is prepared.
[0046] Figure 1 It is a comparison chart of the mechanical properties of the hydrogels prepared in Example 1 and Comparative Examples 1 and 2. In Comparative Example 1, sodium alginate and multi-walled carbon nanotubes were not added, and there was only chemical cross-linking inside. The tensile strength of the prepared polyacrylamide copolymer polyacrylic acid hydrogel was 93 kPa, and the elongation at break was 710%. In Comparative Example 2, sodium alginate was contained, and the tensile strength of the prepared sodium alginate / polyacrylamide copolymer polyacrylic acid interpenetrating network hydrogel increased to 413 kPa, and the elongation at break increased to 853%. This is because the hydroxyl groups in the sodium alginate structure can form coordination bonds with calcium ions, thus forming the first physical cross-linked network, and the copolymerization of acrylamide and acrylic acid constitutes the second chemical cross-linked network. The two act synergistically to endow the interpenetrating network hydrogel with good mechanical properties. Compared with Comparative Example 2, multi-walled carbon nanotubes were added in Example 1, and the tensile strength of the prepared sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube interpenetrating network hydrogel was further increased to 530 kPa, and the elongation at break was increased to 1180%. This is because the oxygen-containing functional groups on the surface of multi-walled carbon nanotubes can form hydrogen bonds with the hydroxyl and carboxyl groups on the molecular chain of sodium alginate, enhancing the network density of the interpenetrating network hydrogel and making the gel network structure more uniform, so as to improve the mechanical strength and toughness of the hydrogel; in addition, multi-walled carbon nanotubes, as a high-performance nano-filler, have the advantages of high modulus and high strength. When the carbon nanotubes are uniformly dispersed in the hydrogel matrix, they can act as a nano-reinforcing phase to effectively transfer and disperse stress, thereby improving the mechanical properties of the hydrogel.
[0047] Figure 2 Comparison chart of the areal specific capacitance of the sodium alginate / polyacrylamide copolyacrylic acid / multi-walled carbon nanotube / polyaniline composite conductive hydrogel prepared in Example 2 and the hydrogels prepared in Comparative Examples 3 and 4. The areal specific capacitance of the composite conductive hydrogel prepared in Example 2 reaches 756.4 mF / cm 2 , and the areal specific capacitance of the hydrogel prepared in Comparative Example 3 is 212.5 mF / cm 2 , and the areal specific capacitance of the hydrogel prepared in Comparative Example 4 is 206.7 mF / cm 2 . The areal specific capacitance of Example 2 is much higher than that of Comparative Examples 3 and 4, mainly due to the excellent conductivity of the added multi-walled carbon nanotubes. The multi-walled carbon nanotubes form a continuous conductive network in the hydrogel, providing an efficient path for electron transport, significantly reducing the resistance of the hydrogel, increasing the conductivity. At the same time, the multi-walled carbon nanotubes can also form a composite conductive network with polyaniline, and the synergistic effect of the two further enhances the charge transport ability.
[0048] Figure 3 are the CV curves of the sodium alginate / polyacrylamide copolyacrylic acid / multi-walled carbon nanotube / polyaniline composite conductive hydrogel prepared in Example 2 at different scanning rates. It can be seen from the figure that there are obvious oxidation-reduction peaks in the CV curves, which are attributed to the transformation between the oxidized and reduced states of polyaniline in the composite conductive hydrogel electrode. As the scanning rate increases, the peak current value of the CV curve continuously increases, and the integral area of the CV curve also gradually increases, but the shape of the CV curve does not change significantly. These phenomena indicate that the prepared sodium alginate / polyacrylamide copolyacrylic acid / multi-walled carbon nanotube / polyaniline composite conductive hydrogel has excellent rate performance and electrochemical reversibility as an electrode material.
[0049] Figure 4 Comparison chart of the mechanical properties of the sodium alginate / polyacrylamide copolyacrylic acid / multi-walled carbon nanotube / polyaniline composite conductive hydrogel prepared in Example 2 and the hydrogels prepared in Comparative Examples 5 and 6. It can be known from the specific implementation that the addition amount of multi-walled carbon nanotubes in Example 2 is 5 mg, the addition amount of multi-walled carbon nanotubes in Comparative Example 5 is 2.5 mg, and the addition amount of multi-walled carbon nanotubes in Comparative Example 6 is 10 mg. Observe Figure 4It can be seen that the tensile strength of the composite conductive hydrogel prepared in Example 2 can reach 805kPa, and the elongation at break can reach 674%. The tensile strength of the hydrogel prepared in Comparative Example 5 is 537kPa, and the elongation at break is 525%. The tensile strength of the hydrogel prepared in Comparative Example 6 is 528kPa, and the elongation at break is 582%. The mechanical properties of the hydrogels prepared in Comparative Examples 5 and 6 are weakened. This is because an appropriate amount of multi-walled carbon nanotubes can be evenly dispersed in the hydrogel matrix, and can form an effective stress transfer network through interaction with polymer molecular chains, and this interaction can reversibly break and reorganize when subjected to force, thereby dissipating external energy, reducing stress concentration, and thus improving the mechanical properties of the hydrogel; when the amount of multi-walled carbon nanotubes added is too much, due to the strong van der Waals force between the carbon nanotubes, it is easy to agglomerate and form larger aggregates, which destroys the uniformity of the hydrogel, causes stress concentration, and becomes a weak point in mechanical properties, thereby reducing the tensile strength and elongation at break of the hydrogel.
[0050] Figure 5 This is a comparison chart of the electrical conductivity of the sodium alginate / polyacrylamide copolymerized acrylic acid / multi-walled carbon nanotube / polyaniline composite conductive hydrogel prepared in Example 2 and the hydrogels prepared in Comparative Examples 5 and 6. The conductivity of the sodium alginate / polyacrylamide copolymer acrylic acid / multi-walled carbon nanotube / polyaniline composite conductive hydrogel prepared in Example 2 reaches 0.12S / m, and the conductivity of the hydrogel prepared in Comparative Examples 5 and 6 are 0.072S / m and 0.07S / m, respectively. The reason for this conductivity difference is the different addition amounts of multi-walled carbon nanotubes: the addition amount of multi-walled carbon nanotubes in Example 2 is 5mg, the addition amount of multi-walled carbon nanotubes in Comparative Example 5 is 2.5mg, and the addition amount of multi-walled carbon nanotubes in Comparative Example 6 is 10mg; the addition of an appropriate amount of multi-walled carbon nanotubes can significantly improve the electrochemical properties of the hydrogel by constructing an efficient conductive network, increasing the electrochemical active surface area, and promoting ion transport; while the addition of excessive multi-walled carbon nanotubes will make it easy for the nanotubes to agglomerate and form aggregates, destroying the continuity of the conductive network, resulting in obstruction of the electron transmission path, thereby reducing the conductivity and electrochemical properties of the hydrogel.
[0051] Figure 6Comparison chart of the conductivity of the sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube interpenetrating network hydrogel prepared in Example 1 and the sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube / polyaniline composite conductive hydrogel prepared in Example 2. It can be seen from the figure that introducing conductive polyaniline into the interpenetrating network hydrogel can endow the composite conductive hydrogel with good conductivity, and its conductivity is increased from the original 0.048 S / m to 0.12 S / m. Polyaniline is a typical conductive polymer. The conjugated π-electron system in its molecular chain can achieve efficient electron transport. And a composite conductive network can be formed between polyaniline and multi-walled carbon nanotubes through π-π synergistic interaction. The synergistic effect of the two further enhances the charge transport ability, enhances the stability of the conductive network, and improves the efficiency of the electrochemical reaction.
[0052] Figure 7 Areal specific capacitance of the sodium alginate / polyacrylamide copolymer polyacrylic acid / multi-walled carbon nanotube / polyaniline composite conductive hydrogel prepared in Example 2 at different current densities. It can be seen from the figure that the areal specific capacitance of the composite conductive hydrogel prepared in Example 2 is 681.1 mF / cm 2 when the current density is 0.5 mA / cm 2 ; when the current density is increased to 2.5 mA / cm 2 , the areal specific capacitance is 472.3 mF / cm 2 , and the capacitance retention rate is 69.4%, indicating that the composite conductive hydrogel has a good capacitance retention rate.
[0053] The above are only the preferred embodiments of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.
Claims
1. A method for preparing a composite conductive hydrogel electrode material, characterized in that: Firstly, sodium alginate, acrylamide and acrylic acid are dissolved in water, then multi-walled carbon nanotubes are added and dispersed evenly, and then a sodium alginate / polyacrylamide copolymer acrylic acid / multi-walled carbon nanotube composite hydrogel is prepared by free radical polymerization, and then the composite hydrogel is cross-linked by calcium chloride to form an interpenetrating network hydrogel, and finally the interpenetrating network hydrogel is swollen by water and placed in an aniline solution for low-temperature pre-infiltration and in-situ polymerization reaction is initiated to obtain a sodium alginate / polyacrylamide copolymer acrylic acid / multi-walled carbon nanotube / polyaniline composite conductive hydrogel electrode material.
2. The method according to claim 1, characterized in that: The following steps are involved: (1) Preparing a dispersion of sodium alginate, acrylamide, acrylic acid and multi-walled carbon nanotubes; (2) adding a crosslinking agent and an initiator to the dispersion to polymerize and prepare a sodium alginate / polyacrylamide copolymer acrylic acid / multi-walled carbon nanotube composite hydrogel; (3) soaking the composite hydrogel prepared in step (2) in a calcium chloride solution to cause a cross-linking reaction to occur, thereby preparing a sodium alginate / polyacrylamide copolymer acrylic acid / multi-walled carbon nanotube interpenetrating network hydrogel; (4) The interpenetrating network hydrogel prepared in step (3) is placed in deionized water for swelling, and then the swollen gel is placed in an aniline solution for low-temperature pre-infiltration, and then an oxidant and a doping acid are added to carry out an in-situ polymerization reaction to obtain the sodium alginate / polyacrylamide copolymer acrylic acid / multi-walled carbon nanotube / polyaniline composite conductive hydrogel electrode material.
3. The method according to claim 2, characterized in that: Step (1) is specifically as follows: 0.3 g of sodium alginate, 2.5 g of acrylamide and 0.5 g of acrylic acid are added to 20 mL of deionized water, and the mixture is stirred and dissolved at room temperature. Subsequently, 5 mg of multi-walled carbon nanotubes are added to the mixture, and the mixture is stirred and dispersed at room temperature for 2 hours to obtain a dispersion of sodium alginate, acrylamide, acrylic acid and multi-walled carbon nanotubes.
4. The method according to claim 2, characterized in that: Step (2) specifically comprises: adding 3 mL of 0.01 g / mL ammonium persulfate solution and 300 μL of 0.01 g / mL N,N'-methylenebisacrylamide solution to the dispersion of sodium alginate, acrylamide, acrylic acid and multi-walled carbon nanotubes, stirring at room temperature for 1 hour to make the dispersion uniform, then ultrasonically degassing for 30 minutes, and then reacting at 65° C. for 5 hours to obtain a sodium alginate / polyacrylamide copolymer acrylic acid / multi-walled carbon nanotube composite hydrogel.
5. The method according to claim 2, characterized in that: Step (3) is specifically: soaking the sodium alginate / polyacrylamide copolymer acrylic acid / multi-walled carbon nanotube composite hydrogel in a 0.1 mol / L calcium chloride solution for 2 hours to allow a cross-linking reaction to occur, and then washing the gel surface with deionized water to remove impurities to obtain a sodium alginate / polyacrylamide copolymer acrylic acid / multi-walled carbon nanotube interpenetrating network hydrogel.
6. The method according to claim 2, characterized in that: Step (4) is specifically as follows: dissolving 0.3887 g of aniline hydrochloride in 30 mL of deionized water, cooling the solution to 0° C., which is referred to as solution I; dissolving 0.4564 g of ammonium persulfate in 2.4 mL of deionized water, adding 600 μL of phytic acid solution with a mass fraction of 50%, stirring evenly, and cooling the solution to 0° C., which is referred to as solution II; placing sodium alginate / polyacrylamide copolymerized acrylic acid / multi-walled carbon nanotube interpenetrating network hydrogel in 250 mL of deionized water for swelling for 48 h, then placing the swollen interpenetrating network hydrogel in solution I for pre-permeation at 0° C. for 30 min, then adding solution II thereto, reacting for 48 h, and then washing the product with deionized water to obtain a sodium alginate / polyacrylamide copolymerized acrylic acid / multi-walled carbon nanotube / polyaniline composite conductive hydrogel.
7. A sodium alginate / polyacrylamide copolymerized acrylic acid / multi-walled carbon nanotube / polyaniline composite conductive hydrogel prepared by the method according to any one of claims 1 to 6.