A covalent organic framework in-situ grown alginate fiber and its preparation method and application

Abstract

The present invention discloses an alginate fiber grown in situ on a covalent organic framework, and a preparation method and application thereof, which solves the technical problems of insolubility, non-flexibility and poor conductivity of alginate fibers of COF materials. The specific process steps of the method are as follows: (1) preparing alginate fibers containing exposed aldehyde groups; (2) using the above fiber segments as a flexible substrate for in situ growth of COF; (3) in situ growth of COF materials on the surface of alginate fibers; (4) catalytic polymerization of conductive polymer PPy in the gaps of COF materials, and cooperating with COF materials to construct a channel for high-speed transmission of electrons / ions. The method described in the present invention is versatile and simple in process, suitable for large-scale production, and the prepared fiber material has good performance in the field of supercapacitors and has high stability and flexibility, and proposes a new strategy for flexible preparation of COF materials.

Description

Technical Field

[0001] The present invention relates to the technical field of supercapacitors, and in particular to a covalent organic framework in-situ grown alginate fiber and a preparation method and application thereof. Background Art

[0002] With the rapid development of flexible and wearable technologies in recent years, devices with high flexibility and high-efficiency electrochemical energy storage performance have attracted the research interests of many scientists. Among them, fiber-shaped supercapacitors (FSCs) have become a substitute material for the next generation of smart fiber products due to their high flexibility, small size, high power density and fast charging and discharging. Although a large number of research results have focused on planar (2D) flexible supercapacitors, their poor air / moisture permeability and environmental compatibility prevent them from being widely used in high-standard wearable electronic products. Therefore, one-dimensional (1D) FSCs have many unique features and promising advantages: (1) FSCs are highly compatible with textiles and can be woven or knitted into breathable / moisture permeable energy fabrics / textiles; (2) FSCs exhibit excellent mechanical flexibility and miniaturized photovoltaic devices, providing a variety of possibilities. However, the low energy density of FSCs is still an important factor limiting its development. Therefore, improving the charge transfer ability of the material is an effective way to develop high-performance energy storage fibers.

[0003] Typically, fiber electrodes are composed of pseudocapacitive active materials, including transition metal oxides and conductive polymers. However, this approach often requires sacrificing power density and cycle life because the redox reactions in most pseudoactive materials are diffusion-controlled, resulting in slow reaction kinetics. Secondly, among conductive polymers, polypyrrole (PPy) has attracted widespread attention due to its high theoretical capacitance, high electronic and ionic conductivity, and environmental stability. The PPy prepared by catalytic polymerization is in powder form and cannot be directly formed into fiber electrodes.

[0004] Covalent organic frameworks (COFs) have attracted a lot of research due to their adjustable pore structure, high specific surface area, reversible redox activity and high chemical stability. Their unique microporous structure and high surface area endow COF-based electrodes with double-layer capacitance properties and provide abundant pore paths. In addition, many active redox sites containing heteroatoms can be integrated into the polymer backbone, providing excellent pseudocapacitive performance. These two contributions make COF materials extremely promising supercapacitor electrode materials. However, COFs are usually insoluble powders and are not easy to process into flexible fiber materials. Summary of the invention

[0005] In view of the problems existing in the above-mentioned prior art, the present invention provides a covalent organic framework in-situ grown alginate fiber and its preparation method and application, so as to solve the shortcomings and deficiencies of covalent organic framework (COF) materials that are insoluble and cannot be made flexible, and grows it in situ on the surface of alginate fibers and applies it to the field of flexible supercapacitor technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The invention discloses an alginate fiber with a covalent organic framework in situ grown, wherein the covalent organic framework is in situ grown on the surface of the alginate fiber.

[0008] Preferably, the covalent organic framework is formed by a two-dimensional or three-dimensional ordered network structure formed by a Schiff base reaction of polyaldehyde small molecules and polyamino small molecules.

[0009] A method for preparing alginate fibers grown in situ on a covalent organic framework as described above comprises the following steps:

[0010] (1) preparing a sodium alginate aqueous solution with a mass percentage of 1% to 5%, adding a sodium periodate aqueous solution, reacting at room temperature in the dark, precipitating with ethanol, and freeze-drying to obtain an aldehyde-modified alginate powder;

[0011] (2) dissolving alginate powder and the aldehyde-modified alginate powder in deionized water in a ratio of 1: (0.1-3) to prepare a spinning solution of 2%-5% by weight, and performing a degassing treatment;

[0012] (3) placing the spinning solution prepared in step (2) in a syringe for wet spinning, wherein the coagulation bath solution is a divalent metal ion salt solution, to form solid alginate fibers, which are then soaked in deionized water and dried to obtain alginate fibers;

[0013] (4) Immersing the alginate fibers obtained in step (3) in an ampoule containing a mixed solution of a ternary aldehyde, a diamine, an organic solvent and glacial acetic acid, degassing the ampoule through a liquid nitrogen cycle, vacuum sealing the ampoule, and heating at 70-100° C. for 1-5 days to obtain alginate fibers with in situ growth of a covalent organic framework.

[0014] Preferably, the method further comprises step (5): soaking the alginate fibers with in-situ growth of the covalent organic framework obtained in step (4) in a 0.5-2M pyrrole solution for 0.5-3 hours, adding an equal volume of 0.25-1M FeCl3·6H2O solution to the soaking solution for catalytic polymerization, the polymerization reaction being carried out in an ice water bath at 0-5°C, reacting for 15-60 minutes, washing with deionized water, and drying to obtain polypyrrole alginate fibers with in-situ growth of the covalent organic framework.

[0015] Preferably, the ternary aldehyde is any one of trialdehyde phloroglucinol, trimesaldehyde and 2,4,6-tris(4-formylphenyl)-1,3,5-triazine.

[0016] Preferably, the diamine is any one of 2,6-diaminoanthraquinone, 4,4-diphenylenediamine, 4,4-diamino-3,3-dimethyl-1,1-biphenyl, 3,3-dihydroxybenzidine and oxalic acid dihydrazide.

[0017] Preferably, the organic solvent is one or more of m-trimethylbenzene, 1,4-dioxane, o-dichlorobenzene and N,N-dimethylacetamide.

[0018] Preferably, the concentration of the glacial acetic acid is 1M-6M.

[0019] Preferably, in step (4),

[0020] The mass ratio of alginate fiber to ternary aldehyde is 1:(0.01-5);

[0021] The mass ratio of alginate fiber to diamine is 1:(0.01-5);

[0022] The mass ratio of alginate fiber to glacial acetic acid is 1:(0.01-10);

[0023] The mass ratio of alginate fiber to organic solvent is 1:(1-100).

[0024] In addition, the present application also provides an application of alginate fibers grown in situ on a covalent organic framework as described above in a supercapacitor.

[0025] The beneficial effects of the present invention are as follows:

[0026] (1) The present invention manufactures alginate fiber flexible substrate by wet spinning, so that the material has biocompatibility, environmental protection, greenness and good safety.

[0027] (2) The present invention solves the shortcomings of COF materials being insoluble and difficult to process by in-situ growing COF materials on the surface of alginate fibers. The preparation method is a new method for preparing COF fiber materials, and the preparation process is simple and easy to prepare on a large scale.

[0028] (3) The COF fiber material prepared by the preparation method provided by the present invention has excellent thermal stability, chemical stability and good mechanical properties, and can be practically applied in the field of flexible supercapacitors. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a scanning electron microscope image of the alginate fiber prepared in Example 1.

[0030] Figure 2 This is a scanning electron micrograph of the in-situ grown alginate fibers of DAAQ-COF prepared in Example 1.

[0031] Figure 3 This is a scanning electron micrograph of the in-situ grown polypyrrole alginate fibers of DAAQ-COF prepared in Example 1.

[0032] Figure 4 This is a scanning electron microscope image of the in-situ grown alginate fibers of BD-COF prepared in Example 2.

[0033] Figure 5 This is a scanning electron micrograph of the in-situ grown alginate fibers of HBD-COF prepared in Example 3.

[0034] Figure 6 This is the XRD pattern of DAAQ-COF prepared in Example 1.

[0035] Figure 7 This is the electrochemical performance diagram of DAAQ-COF-SAF-PPy prepared in Example 1.

[0036] Figure 8 This is the electrochemical performance diagram of BD-COF-SAF-PPy prepared in Example 2.

[0037] Fig. 9 This is the electrochemical performance diagram of HBD-COF-SAF-PPy prepared in Example 3. DETAILED DESCRIPTION

[0038] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is clearly and completely described below in conjunction with the accompanying drawings of the present invention. Based on the embodiments in this application, other similar embodiments obtained by ordinary technicians in this field without making any creative work should all fall within the scope of protection of this application.

[0039] Example 1: This example relates to a method for preparing polypyrrole alginate fibers grown in situ on a covalent organic framework material, and the specific steps are as follows:

[0040] (1) preparing a sodium alginate aqueous solution with a mass percentage of 2%, adding 2 equivalents of sodium periodate aqueous solution, reacting at room temperature in the dark for 24 hours, finally precipitating with ethanol, and freeze-drying to obtain aldehyde-modified sodium alginate powder;

[0041] (2) dissolving sodium alginate powder and aldehyde-modified sodium alginate powder in deionized water at a ratio of 1:0.5 to prepare a spinning solution of 3% by weight, and performing a degassing treatment;

[0042] (3) placing the spinning solution in step (2) in a 10 mL syringe for wet spinning, the extrusion speed is set to 0.5 mL / min, the coagulation bath solution is a calcium chloride solution, and solid calcium alginate fibers are formed. After crosslinking for 2 hours, the fibers are soaked in deionized water for 4 hours, and dried at 50° C. for 8 hours to obtain calcium alginate fibers;

[0043] (4) Take 1 g of the alginate fiber obtained in step (3) and immerse it in an ampoule containing a mixed solution of 31.5 mg of trialdehyde pyrogallol, 53.5 mg of 2,6-diaminoanthraquinone, an organic solvent (m-trimethylbenzene: 1,4-dioxane = 0.8 mL: 0.8 mL) and glacial acetic acid (6M, 320 μL), then degas through liquid nitrogen circulation, vacuum seal the ampoule, and heat at 90°C for 3 days to obtain DAAQ-COF in situ grown alginate fibers.

[0044] (5) The COF in situ grown alginate fibers obtained in step (4) were soaked in a 1M pyrrole solution for 1 hour, and then an equal volume of 0.5M FeCl3·6H2O solution was added to the soaking solution for catalytic polymerization. The polymerization reaction was carried out in an ice water bath at 0°C. After the reaction lasted for 45 minutes, the fibers were washed with deionized water and dried to obtain DAAQ-COF in situ grown polypyrrole alginate fibers (DAAQ-COF-SAF-PPy). In this step, the conductive polymer PPy was catalytically polymerized in the gaps of the COF material, and cooperated with the COF material to construct a channel for high-speed transmission of electrons / ions.

[0045] Example 2: This example relates to a method for preparing polypyrrole alginate fibers grown in situ on a covalent organic framework material, and the specific steps are as follows:

[0046] (1) preparing a sodium alginate aqueous solution with a mass percentage of 1%, adding 2 equivalents of sodium periodate aqueous solution, reacting at room temperature in the dark for 24 hours, finally precipitating with ethanol, and freeze-drying to obtain aldehyde-modified sodium alginate powder;

[0047] (2) dissolving sodium alginate powder and aldehyde-modified sodium alginate powder in deionized water at a ratio of 1:0.1 to prepare a spinning solution of 3% by weight, and performing a degassing treatment;

[0048] (3) placing the spinning solution in step (2) into a 10 mL syringe, setting the extrusion speed to 0.5 mL / min, and using a calcium chloride solution as the coagulation bath solution to form solid calcium alginate fibers, crosslinking for 2 hours and then soaking in deionized water for 4 hours, and drying at 50° C. for 8 hours to obtain calcium alginate fibers;

[0049] (4) 5 g of the alginate fiber obtained in step (3) was immersed in an ampoule containing a mixed solution of 32.4 mg of trimesaldehyde, 55.3 mg of 4,4-diphenylenediamine, an organic solvent (m-trimethylbenzene: 1,4-dioxane = 1.5 mL: 1.5 mL) and glacial acetic acid (6 M, 300 μL), and then degassed by circulating liquid nitrogen, the ampoule was vacuum sealed, and heated at 70°C for 5 days to obtain BD-COF in situ grown alginate fibers;

[0050] (5) The COF in situ grown alginate fibers obtained in step (4) were immersed in a 0.5 M pyrrole solution for 3 hours, and then an equal volume of 1 M FeCl3·6H2O solution was added to the immersed solution to catalyze polymerization. The polymerization reaction was carried out in an ice water bath at 0°C. After the reaction lasted for 15 minutes, the fibers were washed with deionized water and dried to obtain BD-COF in situ grown polypyrrole alginate fibers (BD-COF-SAF-PPy).

[0051] Example 3: This example relates to a method for preparing polypyrrole alginate fibers grown in situ on a covalent organic framework material, and the specific steps are as follows:

[0052] (1) preparing a sodium alginate aqueous solution with a mass percentage of 1%, adding 2 equivalents of sodium periodate aqueous solution, reacting at room temperature in the dark for 24 hours, finally precipitating with ethanol, and freeze-drying to obtain aldehyde-modified sodium alginate powder;

[0053] (2) dissolving sodium alginate powder and aldehyde-modified sodium alginate powder in deionized water at a ratio of 1:5 to prepare a spinning solution of 3% by weight, and performing a degassing treatment;

[0054] (3) placing the spinning solution in step (2) into a 10 mL syringe, setting the extrusion speed to 0.5 mL / min, and using a calcium chloride solution as the coagulation bath solution to form solid calcium alginate fibers, crosslinking for 2 hours and then soaking in deionized water for 4 hours, and drying at 50° C. for 8 hours to obtain calcium alginate fibers;

[0055] (4) 1 g of the alginate fiber obtained in step (3) was immersed in an ampoule containing 42.0 mg of trialdehyde phloroglucinol, 64.9 mg of 3,3-dihydroxybenzidine, an organic solvent (m-trimethylbenzene: 1,4-dioxane = 1.5 mL: 1.5 mL) and a mixed solution of glacial acetic acid (6 M, 300 μL), and then degassed by circulating liquid nitrogen, the ampoule was vacuum sealed, and heated at 100° C. for 1 day to obtain HBD-COF in situ grown alginate fibers;

[0056] (5) The COF in situ grown alginate fibers obtained in step (4) were immersed in a 2M pyrrole solution for 0.5 hours, and then an equal volume of 1M FeCl3·6H2O solution was added to the immersed solution to catalyze polymerization. The polymerization reaction was carried out in an ice water bath at 5°C. After the reaction lasted for 60 minutes, the fibers were washed with deionized water and dried to obtain MBD-COF in situ grown polypyrrole alginate fibers (HBD-COF-SAF-PPy).

[0057] The electrochemical test of the embodiment of the present application was carried out using a half-cell of a three-electrode system, with the prepared COF in situ grown polypyrrole alginate fiber material as the working electrode, the auxiliary electrode and the reference electrode being a platinum electrode and a silver / silver chloride / potassium chloride saturated solution reference electrode, respectively.

[0058] Performance Testing

[0059] (1) Morphology observation:

[0060] Figure 1 The surface of the alginate fiber in the middle sea has grooves and gaps; Figure 2 The worm-like nanoarrays grow on the surface of alginate fibers grown in situ in COF; Figure 3 The surface of the polypyrrole alginate fibers grown in situ in COF is coated by the grown layered materials. Figure 4 and Figure 5 It is also possible to observe the layered material growing on the surface of the agglomerated fibers. Figure 6 The experimental XRD spectrum of the prepared sample showed peaks corresponding to the (100), (110), and (210) crystal planes at 3.36°, 5.78°, and 6.77°, respectively. This result is consistent with the simulated AA stacking pattern.

[0061] (2) Electrochemical performance test:

[0062] Figure 7 In situ growth of polypyrrole alginate fibers for DAAQ-COF

[0063] Electrochemical performance characterization diagram of (DAAQ-COF-SAF-PPy). The results show that this new type of alginate fiber supercapacitor has good capacitive behavior. -2 At the scan rate, the maximum surface capacitance of DAAQ-COF-SAF-PPy can reach 691.25 mF cm -2 .

[0064] Figure 8 The electrochemical performance of BD-COF-SAF-PPy in situ grown polypyrrole alginate fibers (BD-COF-SAF-PPy) is shown in Figure 1. -2At the scan rate, the maximum surface capacitance of BD-COF-SAF-PPy can reach 176mF·cm -2 .

[0065] Fig. 9 The electrochemical performance characterization diagram of HBD-COF in situ grown polypyrrole alginate fiber (HBD-COF-SAF-PPy). The results show that 1.00 mA cm -2 At the scan rate, the maximum surface capacitance of HBD-COF-SAF-PPy can reach 150mF·cm -2 .

[0066] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing polypyrrole alginate fibers grown in situ on a covalent organic framework, characterized in that: The covalent organic framework is grown in situ on the surface of alginate fibers, including the following steps: (1) preparing a sodium alginate aqueous solution with a mass percentage of 1% to 5%, then adding a sodium periodate aqueous solution, reacting at room temperature in the dark, then precipitating with ethanol, and freeze-drying to obtain an aldehyde-modified alginate powder; (2) dissolving alginate powder and the aldehyde-modified alginate powder in deionized water in a ratio of 1:(0.1-3) to prepare a spinning solution of 2%-5% by weight, and performing a degassing treatment; (3) placing the spinning solution prepared in step (2) in a syringe for wet spinning, wherein the coagulation bath solution is a divalent metal ion salt solution, to form solid alginate fibers, which are then soaked in deionized water and dried to obtain alginate fibers; (4) immersing the alginate fibers obtained in step (3) in an ampoule containing a mixed solution of a ternary aldehyde, a diamine, an organic solvent and glacial acetic acid, degassing the ampoule by circulating liquid nitrogen, vacuum sealing the ampoule, and heating at 70-100° C. for 1-5 days to obtain alginate fibers with in situ growth of a covalent organic framework; (5) The alginate fibers with in situ growth of the covalent organic framework obtained in step (4) are immersed in a 0.5-2M pyrrole solution for 0.5-3 hours, and then an equal volume of 0.25-1M FeCl3·6H2O solution is added to the immersed solution for catalytic polymerization. The polymerization reaction is carried out in an ice water bath at 0-5°C. After the reaction time is 15-60 minutes, the fibers are washed with deionized water and dried to obtain polypyrrole alginate fibers with in situ growth of the covalent organic framework.

2. The method for preparing covalent organic framework in-situ grown polypyrrole alginate fibers according to claim 1, characterized in that: The covalent organic framework is formed by a two-dimensional or three-dimensional ordered network structure through a Schiff base reaction between a ternary aldehyde-based small molecule and a diamine-based small molecule.

3. The method for preparing covalent organic framework in-situ grown polypyrrole alginate fibers according to claim 1, characterized in that: The ternary aldehyde is any one of trialdehyde phloroglucinol, trimesaldehyde and 2,4,6-tris(4-formylphenyl)-1,3,5-triazine.

4. The method for preparing covalent organic framework in-situ grown polypyrrole alginate fibers according to claim 1, characterized in that: The diamine is any one of 2,6-diaminoanthraquinone, 4,4-diphenyl diamine, 4,4-diamino-3,3-dimethyl-1,1-biphenyl, 3,3-dihydroxybenzidine and oxalic acid dihydrazide.

5. The method for preparing covalent organic framework in-situ grown polypyrrole alginate fibers according to claim 1, characterized in that: The organic solvent is one or more of m-trimethylbenzene, 1,4-dioxane, o-dichlorobenzene and N,N-dimethylacetamide.

6. The method for preparing covalent organic framework in-situ grown polypyrrole alginate fibers according to claim 1, characterized in that: The concentration of the glacial acetic acid is 1 M-6 M.

7. The method for preparing covalent organic framework in-situ grown polypyrrole alginate fibers according to claim 1, characterized in that: In the step (4), The mass ratio of alginate fiber to ternary aldehyde is 1:(0.01-5); The mass ratio of alginate fiber to diamine is 1:(0.01-5); The mass ratio of alginate fiber to glacial acetic acid is 1:(0.01-10); The mass ratio of alginate fiber to organic solvent is 1:(1-100).

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