MOF (Metal Organic Framework)-based fabric with anti-ultraviolet and color-changing functions as well as preparation method and application thereof

Abstract

The invention relates to an MOF-based fabric with anti-ultraviolet and color-changing functions as well as a preparation method and application of the MOF-based fabric, and belongs to the technical field of fabrics. The preparation method of the MOF-based fabric with the anti-ultraviolet and color-changing functions comprises the following steps: S1, dissolving a metal salt and a ligand in a mixed solvent, then adding a modified cotton fabric, soaking for a period of time, reacting at room temperature, taking out the cotton fabric after the reaction is finished, and washing to obtain the MOF-based fabric with the anti-ultraviolet and color-changing functions; removing the MOF material and impurities physically combined on the surface of the cotton fabric; s2, the step S1 is repeated for multiple times until the cotton fabric is completely covered with the MOF material, and the MOF-based fabric with the anti-ultraviolet and color-changing functions is obtained. The MOF-based fabric is constructed through layer-by-layer self-assembly, so that the MOF-based fabric has ultraviolet resistance and discoloration performance at the same time, and the market requirements are met.

Description

Technical Field

[0001] The present application relates to the technical field of fabrics, and in particular to a MOF-based fabric with both UV resistance and color change functions, and a preparation method and application thereof. Background Art

[0002] In the field of textiles, as consumers' demands for fabric functions become increasingly diversified, the research and development of UV-resistant and color-changing smart fabrics has become a hot topic. Anti-UV fabrics are usually achieved by traditional methods such as adding metal oxides such as titanium dioxide and zinc oxide to the fabric. Although these methods can improve the anti-UV performance of the fabric to a certain extent, they have some limitations, such as affecting the feel, air permeability and durability of the fabric. Color-changing smart fabrics are mostly based on electrochromic or photochromic materials. The application of these materials on fabrics also faces many challenges, such as slow color change response speed, unstable color change effect, poor durability, etc. In addition, in the prior art, when the anti-UV function and the color-changing smart function are integrated into the same fabric, there are problems such as loose combination, mutual interference of functions, and inability to achieve intelligent response, which makes it difficult to meet consumers' demand for multifunctional and intelligent fabrics.

[0003] Implementation schemes in the prior art: 1. Coating method: For example, a coating containing an anti-ultraviolet agent is evenly applied to the surface of the fabric to enhance the anti-ultraviolet performance of the fabric. 2. Physical adsorption method: The color-changing material is adsorbed on the fabric fiber to achieve the color-changing effect of the fabric. 3. Layer-by-layer self-assembly method to construct functional fabrics: This method can achieve the multifunctionality of the fabric by depositing materials with different functions layer by layer. 4. Chemical bonding method: The anti-ultraviolet material and the color-changing material are fixed on the fabric fiber through chemical reaction to form a stable chemical bond to improve the bonding force between the material and the fabric. In these studies, some schemes attempt to combine the anti-ultraviolet and color-changing functions, such as first adding an anti-ultraviolet layer to the fabric through the coating method, and then adding the color-changing material through the physical adsorption method, or using the layer-by-layer self-assembly method to deposit the anti-ultraviolet material and the color-changing material in sequence to achieve the anti-ultraviolet and color-changing functions of the fabric. These schemes have the following defects: 1. Insufficient bonding strength: Whether it is the coating method, physical adsorption method or other methods, the bonding of the anti-ultraviolet material and the color-changing material to the fabric is not strong enough. During the daily use and washing of fabrics, the material is easy to fall off, resulting in the gradual weakening of the fabric's anti-ultraviolet and discoloration properties, affecting the fabric's service life and functional stability. 2. Slow color change response speed: Existing color-changing smart fabrics have a certain lag in color change response speed. For example, the color-changing material fixed by physical adsorption method lacks close interaction with the fabric. When it is stimulated by external stimuli (such as electric field, light, etc.), the color change reaction is not fast enough, which cannot meet the needs of rapid color change, affecting the intelligent color change effect of the fabric. 3. Low functional integration: Although there are many ways to try to integrate anti-ultraviolet and discoloration functions into fabrics, the current technical solutions are still low in functional integration. There may be mutual interference between different functional materials, resulting in the inability to optimize the two functions synergistically, making it difficult to achieve the multifunctional intelligence of the fabric and to give full play to the comprehensive performance of the fabric. 4. Environmental and health risks: Some preparation methods may pose potential risks to the environment and human health. For example, chemical bonding may produce harmful by-products during the reaction process, causing environmental pollution; nanoparticles in nanocomposites may migrate and release during the preparation, use and disposal process, causing adverse effects on the ecosystem and human health.

[0004] In the current textile field, anti-ultraviolet and color-changing smart fabrics have the problems of low functional integration and difficulty in coordinated optimization. When traditional anti-ultraviolet methods such as adding metal oxides are combined with the electrochromic or photochromic materials of color-changing smart fabrics, there are problems such as loose combination, functional interference, and inability to respond intelligently. At the same time, it is difficult for existing technologies to simply control and achieve multifunctional integration, and it is impossible to meet consumers' demand for multifunctional and intelligent fabrics. Therefore, the development of a fabric that can simultaneously have anti-ultraviolet and color-changing properties, and the two functions can be coordinated and optimized and intelligently responded has become a technical problem that needs to be solved urgently. Summary of the invention

[0005] In view of this, the present application provides a MOF-based fabric with both anti-ultraviolet and discoloration functions, and a preparation method and application thereof. The MOF-based fabric constructed by layer-by-layer self-assembly has both anti-ultraviolet and discoloration properties, which meets market demand and can effectively overcome the defects of the above-mentioned prior art.

[0006] The first aspect of the present application provides a method for preparing a MOF-based fabric having both UV resistance and color change functions, comprising the following steps: S1. Dissolving the metal salt and the ligand in a mixed solvent, then adding the modified cotton fabric, soaking for a period of time, reacting at room temperature, and taking out the cotton fabric for washing after the reaction to remove the MOF material and impurities physically bound to the surface of the cotton fabric; S2. Repeat step S1 several times until the cotton fabric is completely covered by the MOF material, thereby obtaining a MOF-based fabric with both UV resistance and color change functions.

[0007] Specifically, after the MOF-based fabric is prepared, it can be post-processed to further improve the performance of the fabric. For example, the MOF-based fabric can be treated with waterproof, oil-proof and anti-fouling finishing agents to improve the durability and easy care of the MOF-based fabric; or some physical treatments, such as heat treatment and high-pressure treatment, can be performed to make the combination between the MOF material and the fabric more stable, and at the same time improve the feel and appearance quality of the MOF-based fabric.

[0008] The present application performs layer-by-layer self-assembly on cotton fabric in the form of coordination bonds, which not only ensures a strong bonding force between MOF and fabric, but also does not produce harmful by-products during the bonding process; at the same time, the fabric is given color-changing properties by photochromic MOF, and the color-changing mechanism is free radical color change, which ensures a rapid response; in addition, the morphology of MOF on the fabric is controlled to achieve anti-ultraviolet properties; the method of the present application kills two birds with one stone, ensuring the multifunctional intelligence of the material and giving full play to the comprehensive performance of the fabric.

[0009] Preferably, in step S1, the modification process of the cotton fabric is: immersing the cotton gauze in a mixed solution containing sodium chloroacetate and sodium hydroxide, stirring at room temperature for reaction, washing the carboxymethylated cotton gauze with deionized water after the reaction to remove residual reagents, and then drying at room temperature overnight to obtain modified cotton fabric.

[0010] Preferably, the ratio of the cotton gauze to the mixed solution is 0.1 g: 10 mL.

[0011] Preferably, the mixed solution is a mixed solution containing 1 M sodium chloroacetate and 5% sodium hydroxide.

[0012] Preferably, the reaction time is 1 h.

[0013] Preferably, in step S1, the metal salt is zinc nitrate hexahydrate, the ligand includes 1-carboxyl-4' 4-bipyridine and terephthalic acid, or the ligand includes 1-carboxyl-4' 4-bipyridine and isophthalic acid.

[0014] Specifically, in addition to using Zn-MOF materials, other MOF materials with color-changing functions can also be tried, and the combination of anti-ultraviolet and color-changing properties can be achieved by regulating the combination of MOF and fabric. For example, other metal organic framework materials with similar functions to Zn-MOF, but not limited to MOFs with cadmium (Cd), silver (Ag), aluminum (Al), etc. as central metals, or some photochromic MOFs reported in the literature. Or new polymer materials with unique electronic structures, such as conjugated polymers, functionalized polymers, etc., can be used to effectively absorb ultraviolet rays and achieve intelligent color change by adjusting their molecular structure and composition.

[0015] Preferably, the mass ratio of zinc nitrate hexahydrate to 1-carboxy-4'-4-bipyridine is 0.0297 g:0.0204 g.

[0016] Preferably, in steps S1 and S2, the MOF material is a photochromic carboxylic acid MOF.

[0017] Preferably, in step S1, the mixed solvent is a mixed aqueous solution containing N,N-dimethylformamide and methanol.

[0018] The second aspect of the present application also provides a MOF-based textile fabric having both UV resistance and color change functions, which is prepared by the above-mentioned preparation method.

[0019] Compared with the prior art, this application has the following beneficial effects: 1. Innovative material combination method: The layer-by-layer self-assembly method is used to construct MOF-based fabrics, which makes the MOF material and fabric more tightly and evenly combined, effectively improving the bonding firmness and stability between the material and the fabric, and overcoming the problems of easy material shedding and poor functional stability in the existing technology. This innovative combination method not only enhances the fabric's anti-ultraviolet and discoloration properties, but also achieves the synergistic optimization of the two functions, so that the fabric can maintain good functional performance under different environmental conditions.

[0020] 2. Multifunctional integration and synergistic optimization: This application utilizes a MOF material for one-step synthesis and successfully integrates the two functions of UV resistance and color change into the same fabric. Different from the low functional integration solutions in the prior art, this application rationally designs and optimizes the structure and performance of MOF materials to make the anti-ultraviolet and color change functions cooperate with each other and synergize with each other.

[0021] 3. Innovation of preparation process: The preparation method adopted in this application is characterized by simple operation, low cost and high production efficiency. Compared with some solutions with complex preparation processes and high costs in the prior art, it has obvious competitive advantages. The innovative preparation process of this application not only reduces production costs, but also improves production efficiency, which is conducive to the promotion and application of MOF-based fabrics in this application in the market. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the present application or the prior art, the drawings required for use in the description of the present application or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 (a) is the asymmetric unit ball-and-stick diagram of Zn-MOF in Example 1 of the present application, Figure 1 (b) is a schematic diagram of the π-π stacking between the base layer and the layer of the two-dimensional coordination diagram of Zn-MOF in Example 1 of the present application; Figure 2 The X-ray powder diffraction patterns of the simulated and experimental samples of Zn-MOF in Example 1 of the present application; Figure 3 (a) is a SEM image of the original fabric in Example 1 of the present application, Figure 3 (b) is a SEM image of the MOF-based fabric in Example 1 of the present application; Figure 3 (c) SEM image of the composite fabric treated with physical adsorption in Comparative Example 2; Figure 3 (d) SEM image of the composite fabric printed with coating in Comparative Example 3; Figure 4 This is a diagram showing the color change of the MOF-based fabric before and after illumination in Example 1 of the present application; Figure 5 This is a graph of the K / S value of the MOF-based fabric before and after illumination in Example 1 of the present application; Figure 6 This is a comparison chart of the UV protection UPF values ​​of different MOF and fabric combination methods. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with the drawings in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0025] Unless otherwise specified, the experimental methods used in the examples of this application are all conventional methods.

[0026] In the following examples, unless otherwise specified, all raw materials can be obtained by commercial purchase or conventional methods.

[0027] Example 1

[0028] The MOF-based fabric is constructed by coordination self-assembly using a photochromic carboxylic acid MOF (Zn-MOF used in this example) and modified cotton fabric. The specific steps are as follows: 1. Modification of cotton fabric: Immerse cotton gauze (0.1 g) in 10 mL of a solution containing 1 M sodium chloroacetate and 5% sodium hydroxide, and react for 1 h under stirring at room temperature; after the reaction, wash the carboxymethylated cotton gauze with deionized water to remove residual reagents, and then dry it at room temperature overnight.

[0029] 2. Synthesis of MOF-based fabrics: ① Dissolve the metal salt Zn(NO3)2·6H2O (0.0297 g), the first ligand 1-carboxy-4'4-bipyridine (0.0204 g) and the second ligand terephthalic acid (16.7 mg) in a mixed aqueous solution containing DMF and methanol; ② Then soak the modified cotton fabric in the above mixed aqueous solution for 24 hours, place it at room temperature for reaction for 5 days, take out the cotton fabric and wash the MOF material and impurities physically bound to the fabric surface with clean deionized water; ③ Repeat the above processes ① and ② many times until the cotton fabric is completely covered with MOF material.

[0030] Example 2

[0031] The MOF-based fabric and preparation method thereof provided in this embodiment can refer to Example 1, except that Zn-MOF is replaced by Cd-MOF, that is, the metal salt Zn(NO3)2·6H2O is replaced by Cd(NO3)2·4H2O for preparation.

[0032] Example 3

[0033] The MOF-based fabric and preparation method thereof provided in this embodiment can refer to Example 1, except that Zn-MOF is replaced by Ag-MOF, that is, the metal salt Zn(NO3)2·6H2O is replaced by Ag(NO3)2, and the reaction conditions are changed from open to sealed and light-proof conditions, mainly to avoid silver oxidation.

[0034] Example 4

[0035] The MOF-based fabric and preparation method thereof provided in this embodiment can refer to Example 1, except that Zn-MOF is replaced by another new Zn-MOF', that is, the second ligand terephthalic acid is replaced by isophthalic acid for preparation.

[0036] Comparative Example 1

[0037] The original cloth provided in this comparative example can refer to Example 1, except that it is not covered with Zn-MOF material.

[0038] Comparative Example 2

[0039] The physical adsorption method provided in this comparative example can refer to the fabric dyeing method, which is mainly to prepare Zn-MOF and anhydrous methanol into a uniform dispersion. Cotton fabric is placed in the Zn-MOF mixed solution, and based on the weak interaction between Zn-MOF and the cotton fabric structure and the pore structure of the cotton fabric tissue, a magnetic stirrer is used to stir at room temperature for 12 hours to form a MOF adsorption-modified fabric.

[0040] Comparative Example 3

[0041] The coating method provided in this comparative example can refer to the flat screen printing method. First, Zn-MOF is mixed with a corresponding amount of adhesive, thickener, water, etc. to form a color paste, and the prepared color paste is used to perform a printing coating treatment on the cotton fabric. The printed cotton fabric is pasted on a plate at a temperature of about 45 o C's hot platen, then press the patterned flat screen onto the cotton fabric, and then use a scraper to print the prepared color paste onto the fabric. After scraping, the fabric is dried and then baked.

[0042] Test Example 1

[0043] Structural characterization of Zn-MOF: Through X-ray single crystal diffraction, it can be concluded that Zn-MOF is a monoclinic system, belonging to P 2 1 / c Space group. Figure 1 As shown in (a), the simplest asymmetric unit of Zn-MOF contains a crystallographically independent Zn 2+ The Zn ion is coordinated with one CEbpy ligand, two semi- p -BDC 2- The ligand is connected to a coordinated water molecule. Among them, the Zn ion can form a slightly distorted pentagonal bipyramidal structure consisting of three different p -BDC 2-The five O atoms in the ligand, one O atom from the CEbpy ligand and one O atom from the coordinated water are coordinated. A precise comparison revealed that the distance of the Zn-O bond is 2.273 Å~2.414 Å, while the N atom in CEbpy does not participate in the coordination, but forms a stronger hydrogen bond O(7)-H…N(2) (2.040 Å) with the coordinated water molecule, and another strong hydrogen bond O(7)-H…O(2) (1.887 Å) with the carboxylic acid O atom in the CEbpy ligand on the other side that does not participate in the coordination. Figure 1 (b)). Each Zn 2+ The cluster can be regarded as the second simplest structural unit (SBU), which consists of four p -BDC 2- The ligands are surrounded and connected to form a bidentate chelate coordination mode. The two-dimensional layers form a supramolecular array through π-π stacking between benzene rings (center-to-center distance is 3.766 Å) and hydrogen bonding stacking.

[0044] Test Example 2

[0045] Zn-MOF pure phase characterization: like Figure 2 As shown in the figure, the powder data of Zn-MOF was simulated using Mercury V1.4 software and the results of single crystal analysis, and then the synthesized sample was ground and pressed into a tablet and tested by a powder testing instrument. The purity of the synthesized Zn-MOF was tested by the similarity between the simulated and experimental PXRD spectra. The PXRD spectrum of the synthesized Zn-MOF completely matches the diffraction peaks simulated by the single crystal data, indicating that the compound has good purity and uniformity, and the synthesized crystal is pure phase.

[0046] Test Example 3

[0047] The surface of the fabric after MOF treatment was observed using SEM. Figure 3 The SEM spectrum is at a magnification of 500 times. Figure 3 (a) shows that the original cloth fiber surface is smooth and long strips. Figure 3 (b) and Figure 3 (c) The fabric fiber surface is covered with MOF crystals to varying degrees. Figure 3 In (b), the MOF-based fabric fibers formed by layer-by-layer self-assembly are covered with relatively dense chips. Figure 3 The chips on the surface of the fabric fibers in (c) are relatively sparse, mainly because the fibers in the layer-by-layer self-assembly have been pretreated to have regular active -COOH on their surface that can coordinate with metal ions for self-assembly, inducing the regular growth of MOF chips on the fabric surface. Figure 3 (d) Printed coated fabric Due to the role of binder and thickener, MOF is bound to the fiber in the form of a coating.

[0048] Test Example 4

[0049] Photochromic properties of Zn-MOF based fabrics: like Figure 4 As shown, after the Zn-MOF-based fabric was irradiated under UV light (mercury lamp, 365 nm, 175 W) for 5 minutes, the color changed to light purple, and after 20 minutes of irradiation, it turned into dark purple, and the color was fully saturated.

[0050] Test Example 5

[0051] Color-changing properties of Zn-MOF-based fabrics: like Figure 5 As shown in the figure, when the wavelength is greater than 420 nm, the K / S value of the Zn-MOF-based fabric after illumination is greater than the K / S value before illumination, and a peak value appears at a wavelength of 550 nm, mainly due to the deepening of dyeing depth, increased color brightness and color saturation.

[0052] Test Example 6

[0053] UV resistance of Zn-MOF based fabrics: In the national standard, the highest specified value of UPF for textiles is 50+, which basically has no effect on the human body. Figure 6 As shown in the figure, the UPF value of the original fabric is 12.21, which is less than 50, and it does not have anti-ultraviolet performance. The UPF values ​​of the three photosensitive fabrics are all greater than 50, and the anti-ultraviolet performance is good. Among them, the UPF value of the layer-by-layer self-assembled fabric is as high as 159.33, and the anti-ultraviolet performance is the best. It can be seen that Zn-MOF and its coating have good anti-ultraviolet performance after being combined with cotton fabrics. Therefore, MOFs coatings can be widely used in daily textile industries such as umbrellas, tents, and clothing.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a MOF-based fabric with both UV resistance and color change function, characterized in that: The following steps are involved: S1. Dissolving the metal salt and the ligand in a mixed solvent, then adding the modified cotton fabric, soaking for a period of time, reacting at room temperature, and taking out the cotton fabric for washing after the reaction to remove the MOF material and impurities physically bound to the surface of the cotton fabric; S2. Repeat step S1 several times until the cotton fabric is completely covered by the MOF material, thereby obtaining a MOF-based fabric with both UV resistance and color change functions.

2. The method for preparing a MOF-based fabric with both UV resistance and color change function according to claim 1, characterized in that: In step S1, the modification process of the cotton fabric is: immersing the cotton gauze in a mixed solution containing sodium chloroacetate and sodium hydroxide, stirring at room temperature for reaction, washing the carboxymethylated cotton gauze with deionized water after the reaction to remove residual reagents, and then drying at room temperature overnight to obtain modified cotton fabric.

3. The method for preparing a MOF-based fabric with both UV resistance and color change function according to claim 2, characterized in that: The dosage ratio of the cotton gauze to the mixed solution is 0.1 g: 10 mL.

4. The method for preparing a MOF-based fabric with both UV resistance and color change function according to claim 2, characterized in that: The mixed solution is a mixed solution containing 1 M sodium chloroacetate and 5% sodium hydroxide.

5. The method for preparing a MOF-based fabric with both UV resistance and color change function according to claim 2, characterized in that: In step S1, the reaction time is 1 h.

6. The method for preparing a MOF-based fabric with both UV resistance and color change function according to claim 1, characterized in that: In step S1, the metal salt is zinc nitrate hexahydrate, the ligand includes 1-carboxyl-4' 4-bipyridine and terephthalic acid, or the ligand includes 1-carboxyl-4' 4-bipyridine and isophthalic acid.

7. The method for preparing a MOF-based fabric with both UV resistance and color change function according to claim 6, characterized in that: The mass ratio of the zinc nitrate hexahydrate to 1-carboxy-4'-4-bipyridine is 0.0297 g: 0.0204 g.

8. The method for preparing a MOF-based fabric with both UV resistance and color change function according to claim 1, characterized in that: In steps S1 and S2, the MOF material is a photochromic carboxylic acid MOF.

9. The method for preparing a MOF-based fabric with both UV resistance and color change function according to claim 1, characterized in that: In step S1, the mixed solvent is a mixed aqueous solution containing N, N-dimethylformamide and methanol.

10. The MOF-based textile fabric with both UV resistance and color change function obtained by the preparation method according to any one of claims 1 to 9.

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