MOF-based fabric with ultraviolet resistance and color-changing functions, its preparation method and application

Abstract

This application relates to a MOF-based fabric with both ultraviolet resistance and color-changing functions, its preparation method and application, belonging to the technical field of fabric. The preparation method of the MOF-based fabric with both ultraviolet resistance and color-changing functions in this application includes the following steps: S1. Dissolve metal salts and ligands in a mixed solvent, then add a modified cotton fabric, soak for a period of time, and then react at room temperature. After the reaction is completed, take out the cotton fabric and wash it to remove the physically bound MOF material and impurities on the surface of the cotton fabric; S2. Repeat step S1 several times until the cotton fabric is completely covered with the MOF material to obtain a MOF-based fabric with both ultraviolet resistance and color-changing functions. The MOF-based fabric constructed by layer-by-layer self-assembly in this application has both ultraviolet resistance and color-changing properties, meeting the market demand.

Description

Technical Field

[0001] The present application relates to the technical field of fabric materials, and particularly to a MOF-based fabric material with both ultraviolet resistance and color-changing functions, and a preparation method and application thereof. Background Art

[0002] In the field of textiles, with the increasingly diverse functional requirements of consumers for fabrics, the research and development of ultraviolet-resistant and color-changing intelligent fabrics have become a hot topic. Ultraviolet-resistant 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 ultraviolet resistance of the fabric to a certain extent, there are some limitations, such as affecting the hand feeling, breathability and durability of the fabric. Color-changing intelligent fabrics are mostly based on electrochromic or photochromic materials, and the application of these materials on fabrics also faces many challenges, such as slow color-changing response speed, unstable color-changing effect, poor durability, etc. In addition, in the prior art, when integrating the ultraviolet resistance function and the color-changing intelligent function into the same fabric, there are problems such as loose combination, mutual interference of functions, and inability to achieve intelligent response, making it difficult to meet the requirements of consumers for multi-functional and intelligent fabric materials.

[0003] Implementation solutions in the prior art: I. Coating method: For example, a coating containing an anti-ultraviolet agent is evenly coated on the surface of the fabric to enhance the anti-ultraviolet performance of the fabric. II. Physical adsorption method: The color-changing material is adsorbed on the fabric fibers to achieve the color-changing effect of the fabric. III. Layer-by-layer self-assembly method to construct functional fabrics: This method can achieve the multi-functionalization of fabrics by depositing materials with different functions layer by layer. IV. Chemical bonding method: The anti-ultraviolet material and the color-changing material are fixed on the fabric fibers through chemical reactions to form stable chemical bonds, improving the binding force between the materials and the fabric. In these studies, some solutions attempt to combine the anti-ultraviolet and color-changing functions. For example, an anti-ultraviolet layer is added to the fabric by the coating method first, and then the color-changing material is added by the physical adsorption method, or the anti-ultraviolet material and the color-changing material are deposited sequentially by the layer-by-layer self-assembly method to achieve the anti-ultraviolet and color-changing functions of the fabric. These solutions have the following defects: 1. Insufficient binding firmness: Whether it is the coating method, the physical adsorption method or other methods, the binding of the anti-ultraviolet material and the color-changing material to the fabric is not firm enough. During the daily use and washing of the fabric, the materials are prone to falling off, resulting in the gradual weakening of the anti-ultraviolet and color-changing properties of the fabric, affecting the service life and functional stability of the fabric. 2. Slow color-changing response speed: The existing color-changing smart fabrics have a certain lag in the color-changing response speed. For example, the color-changing material fixed by the physical adsorption method lacks a close interaction with the fabric, and when stimulated by the outside world (such as electric field, light, etc.), the color-changing reaction is not rapid enough to meet the requirement of rapid color change, affecting the intelligent color-changing effect of the fabric. 3. Low functional integration degree: Although there are various methods to attempt to integrate the anti-ultraviolet and color-changing functions into the fabric, the current technical solutions still have a low functional integration degree. There may be interference between different functional materials, resulting in the inability to optimize the two functions synergistically, making it difficult to achieve the multi-functional intelligence of the fabric and unable 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, the chemical bonding method may produce harmful by-products during the reaction process, polluting the environment; the nanoparticles in the nanocomposites may migrate and be released during the preparation, use and disposal processes, having an adverse impact on the ecosystem and human health.

[0004] In the current textile field, there are problems of low functional integration degree and difficulty in synergistic optimization for anti-ultraviolet and color-changing smart fabric materials. Traditional anti-ultraviolet methods such as adding metal oxides have problems such as loose binding, functional interference, and inability to respond intelligently when combined with electrochromic or photochromic materials of color-changing smart fabrics. At the same time, it is difficult to simply regulate and control the existing technology to achieve multi-functional integration, unable to meet the needs of consumers for multi-functional and intelligent fabric materials. Therefore, developing a fabric material that can simultaneously possess anti-ultraviolet and color-changing properties, and the two functions can be synergistically optimized and respond intelligently has become an urgent technical problem to be solved. Summary of the Invention

[0005] In view of this, the present application provides a MOF-based fabric material with both ultraviolet resistance and color-changing functions, its preparation method and application. By constructing a MOF-based fabric through layer-by-layer self-assembly, it enables the fabric to have both ultraviolet resistance and color-changing properties, meeting the market demand and effectively overcoming the defects existing in the above-mentioned prior art.

[0006] The first aspect of the present application provides a preparation method of a MOF-based fabric material with both ultraviolet resistance and color-changing functions, including the following steps:

[0007] S1. Dissolve a metal salt and a ligand in a mixed solvent, then add a modified cotton fabric, soak for a period of time, and then react at room temperature. After the reaction is completed, take out the cotton fabric and wash it to remove the physically bonded MOF material and impurities on the surface of the cotton fabric;

[0008] S2. Repeat step S1 several times until the cotton fabric is completely covered with the MOF material, obtaining a MOF-based fabric material with both ultraviolet resistance and color-changing functions.

[0009] Specifically, after the preparation of the MOF-based fabric material, some post-treatments can be carried out to further improve the performance of the fabric. For example, treat the MOF-based fabric material with a waterproof, oil-proof, and stain-proof finishing agent to improve the durability and easy care of the MOF-based fabric material; or carry out some physical treatments, such as heat treatment, high-pressure treatment, etc., to make the combination between the MOF material and the fabric more stable, and at the same time, it can also improve the hand feeling and appearance quality of the MOF-based fabric material.

[0010] In the present application, layer-by-layer self-assembly is carried out on the cotton fabric in the form of coordination bonds, which not only ensures a strong binding force between the MOF and the 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 the photochromic MOF, and the color-changing mechanism is free radical color change, ensuring rapid response; in addition, the ultraviolet resistance is achieved by controlling the morphology of the MOF on the fabric; the method of the present application kills two birds with one stone to ensure the multi-functional intelligence of the material and fully exert the comprehensive performance of the fabric.

[0011] Preferably, in step S1, the modification process of the cotton fabric is: immerse the cotton gauze in a mixed solution containing sodium chloroacetate and sodium hydroxide, stir and react at room temperature. After the reaction is completed, wash the carboxymethylated cotton gauze with deionized water to remove the residual reagents, and then dry it overnight at room temperature to obtain the modified cotton fabric.

[0012] Preferably, the dosage ratio of the cotton gauze to the mixed solution is 0.1 g : 10 mL.

[0013] Preferably, the mixed solution is a mixed solution containing 1 M sodium chloroacetate and 5% sodium hydroxide.

[0014] Preferably, the reaction time is 1 h.

[0015] Preferably, in step S1, the metal salt is zinc nitrate hexahydrate, and the ligands include 1-carboxy-4,4'-bipyridine and terephthalic acid, or the ligands include 1-carboxy-4,4'-bipyridine and isophthalic acid.

[0016] 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 binding mode between the MOF and the fabric. For example, other metal-organic framework materials similar to Zn-MOF, but not limited to MOFs with cadmium (Cd), silver (Ag), aluminum (Al), etc. as the central metal, or some photochromic MOFs reported in the current literature. Or a novel polymer material with a unique electronic structure, such as conjugated polymers, functionalized polymers, etc., can be used. By adjusting its molecular structure and composition, it can effectively absorb ultraviolet light and achieve intelligent color change.

[0017] Preferably, the mass ratio of zinc nitrate hexahydrate to 1-carboxy-4,4'-bipyridine is 0.0297 g:0.0204 g.

[0018] Preferably, in steps S1 and S2, the MOF material is a photochromic carboxylic acid-based MOF.

[0019] Preferably, in step S1, the mixed solvent is a mixed aqueous solution containing N,N-dimethylformamide and methanol.

[0020] The second aspect of the present application also provides a MOF-based fabric material with both anti-ultraviolet and color-changing functions prepared by the above preparation method.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] 1. Innovative material combination method: The MOF-based fabric material is constructed by the layer-by-layer self-assembly method, which makes the combination of the MOF material and the fabric closer and more uniform, effectively improving the binding firmness and stability of the material and the fabric, and overcoming the problems of easy material shedding and poor functional stability in the prior art. This innovative combination method not only enhances the anti-ultraviolet and color-changing properties of the fabric, but also realizes the synergistic optimization of the two functions, enabling the fabric to maintain good functional performance under different environmental conditions.

[0023] 2. Multifunctional integration and collaborative optimization: This application uses a one-step synthesis of a MOF material to successfully integrate the functions of ultraviolet resistance and color change onto the same fabric. Different from the prior art solutions with low functional integration, this application rationally designs and optimizes the structure and properties of the MOF material, enabling the ultraviolet resistance and color change functions to cooperate with each other and synergistically enhance their effects.

[0024] 3. Innovation in the preparation process: The preparation method adopted in this application is characterized by simple operation, low cost, and high production efficiency. Compared with some prior art solutions with complex preparation processes and high costs, it has obvious competitive advantages. The innovative preparation process of this application not only reduces the production cost but also improves the production efficiency, which is conducive to the popularization and application of the MOF-based fabric in the market. Description of the Drawings

[0025] To more clearly illustrate the technical solutions in this application or the prior art, the following will briefly introduce the drawings required for the description of this application or the prior art. Obviously, the drawings in the following description are some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0026] Figure 1 (a) is the asymmetric unit ball-and-stick diagram of Zn-MOF in Example 1 of this application; Figure 1 (b) is the schematic diagram of π-π stacking between layers of the two-dimensional coordination map of Zn-MOF in Example 1 of this application;

[0027] Figure 2 is the X-ray powder diffraction pattern of the simulated and experimental samples of Zn-MOF in Example 1 of this application;

[0028] Figure 3 (a) is the SEM image of the original fabric in Example 1 of this application; Figure 3 (b) is the SEM image of the MOF-based fabric in Example 1 of this application; Figure 3 (c) is the SEM image of the composite fabric treated by physical adsorption in Comparative Example 2; Figure 3 (d) is the SEM image of the composite fabric with coating printing in Comparative Example 3;

[0029] Figure 4 is the color change diagram of the MOF-based fabric before and after illumination in Example 1 of this application;

[0030] Figure 5 is the K / S value diagram of the MOF-based fabric before and after illumination in Example 1 of this application;

[0031] Figure 6 is the comparison diagram of the ultraviolet protection UPF values of different MOF and fabric combination methods. Detailed implementation manners

[0032] To make the objectives, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be clearly and completely described below in conjunction with the accompanying drawings in the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without making creative efforts fall within the scope of protection of the present application.

[0033] Unless otherwise specified, the experimental methods used in the embodiments of the present application are all conventional methods.

[0034] In the following embodiments, unless otherwise specified, all raw materials can be obtained through commercial purchase or conventional methods.

[0035] Embodiment 1

[0036] A MOF-based fabric was constructed by coordination self-assembly using a photochromic carboxylic acid-based MOF (Zn-MOF used in this embodiment) and the modified cotton fabric. The specific steps are as follows:

[0037] 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 under stirring at room temperature for 1 h; after the reaction, wash the carboxymethylated cotton gauze with deionized water to remove the residual reagents, and then dry it overnight at room temperature.

[0038] 2. Synthesis of MOF-based fabric: ① Dissolve metal salt Zn(NO3)2·6H2O (0.0297 g), first ligand 1-carboxy-4,4'-bipyridine (0.0204 g) and second ligand terephthalic acid (16.7 mg) in a mixed aqueous solution containing DMF and methanol; ② Then immerse the modified cotton fabric in the above mixed aqueous solution and soak for 24 hours, and then place it at room temperature to react for 5 days. After taking out the cotton fabric, wash the MOF material and impurities physically bound on the fabric surface with clean deionized water; ③ Repeat the above processes ① and ② multiple times until the cotton fabric is completely covered with the MOF material.

[0039] Embodiment 2

[0040] The MOF-based fabric and its preparation method provided in this embodiment can refer to Embodiment 1, the difference being that Zn-MOF is replaced by Cd-MOF, that is, metal salt Zn(NO3)2·6H2O is replaced by Cd(NO3)2·4H2O for preparation.

[0041] Embodiment 3

[0042] The MOF-based fabric and its preparation method provided in this example can refer to Example 1. The difference is that Zn-MOF is replaced by Ag-MOF, that is, the metal salt Zn(NO3)2·6H2O is replaced by Ag(NO3)2. At the same time, the reaction conditions are changed from an open type to a sealed and light-shielded condition for preparation, mainly to avoid the occurrence of silver oxidation.

[0043] Example 4

[0044] The MOF-based fabric and its preparation method provided in this example can refer to Example 1. The difference is that Zn-MOF is replaced by another new Zn-MOF', that is, the second ligand terephthalic acid is replaced by isophthalic acid for preparation.

[0045] Comparative Example 1

[0046] The original fabric provided in this comparative example can refer to Example 1. The difference is that the Zn-MOF material is not covered.

[0047] Comparative Example 2

[0048] The physical adsorption method provided in this comparative example can refer to the fabric dyeing method. Mainly, Zn-MOF and anhydrous methanol are prepared into a uniformly dispersed liquid. The cotton fabric is put into the Zn-MOF mixed solution. Based on the weak interaction between the structure of Zn-MOF and the cotton fabric and the pore structure of the cotton fabric tissue, it is stirred with a magnetic stirrer at room temperature for 12 hours to form a MOF-adsorbed and modified fabric.

[0049] Comparative Example 3

[0050] The coating method provided in this comparative example can refer to the flat screen printing method. First, Zn-MOF and the corresponding amounts of binder, thickener, water, etc. are formulated into a color paste, and the cotton fabric is subjected to printing and coating treatment with the prepared color paste. The printed cotton fabric is pasted on a hot plate at a temperature of about 45 o °C, then the flat screen engraved with patterns is pressed on the cotton fabric, and the prepared color paste is scraped onto the fabric with a squeegee. After scraping, the fabric is dried and then subjected to baking treatment.

[0051] Test Example 1

[0052] Structural characterization of Zn-MOF:

[0053] It can be obtained by X-ray single crystal diffraction method that Zn-MOF is monoclinic and belongs to the P 2 1 / c space group. As Figure 1 shown in (a), the simplest asymmetric unit of Zn-MOF contains a crystallographically independent Zn 2+ ion, and this Zn ion is coordinated in a 7-coordination mode with one CEbpy ligand and two halfp -BDC 2- The ligand is connected to a coordinated water molecule. Among them, the Zn ion can form a slightly distorted pentagonal bipyramid structure, which consists of three different p -BDC 2- ligands, one O atom from the CEbpy ligand, and one O atom from the coordinated water molecule. Precise comparison reveals that the distance of the Zn-O bond is 2.273 Å - 2.414 Å, and the N atom in CEbpy does not participate in 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 uncoordinated carboxylic acid O atom in the CEbpy ligand on the other side ( Figure 1 (b)). Each Zn 2+ cluster can be regarded as the second simplest structural unit (SBU), which is surrounded and connected by four p -BDC 2- ligands to form a bidentate chelating coordination mode. The two-dimensional layers are stacked through π-π stacking between benzene rings (center-to-center distance is 3.766 Å) and hydrogen bond stacking to form a supramolecular array.

[0054] Test Example 2

[0055] Characterization of the pure phase of Zn-MOF:

[0056] As Figure 2 shown, the powder data of Zn-MOF was simulated using Mercury V1.4 software and the results of single crystal analysis. 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 pattern of the synthesized Zn-MOF completely matches the diffraction peaks simulated from the single crystal data, indicating that the compound has good purity and uniformity, and the synthesized crystal is a pure phase.

[0057] Test Example 3

[0058] The surface condition of the fabric after MOF treatment was observed by SEM. Figure 3 is the SEM spectrum at a magnification of 500 times. It can be seen from Figure 3 (a) that the surface of the original fabric fiber is smooth and strip-shaped. While Figure 3 (b) and Figure 3 (c) show that the surface of the fabric fibers is covered with flaky MOF crystals to varying degrees. Comparison reveals that Figure 3 (b) has a relatively dense coverage of wafers on the surface of the MOF-based fabric fibers formed by layer-by-layer self-assembly, while Figure 3(c) The wafers on the surface of the fabric fibers are relatively sparse, mainly because the fibers in the layer-by-layer self-assembly are pretreated so that there are regular active -COOH on their surfaces, which can coordinate and self-assemble with metal ions, inducing the regular growth of MOF wafers on the fabric surface. Figure 3 (d) Due to the action of adhesives and thickeners, MOF is combined with the fibers in the form of a coating on the printed coated fabric.

[0059] Test Example 4

[0060] Photochromic properties of Zn-MOF-based fabric:

[0061] As Figure 4 shown, after the Zn-MOF-based fabric is irradiated under an ultraviolet lamp (mercury lamp, 365 nm, 175 W) for 5 minutes, the color turns light purple, and turns dark purple after 20 minutes of irradiation, and the color is completely saturated.

[0062] Test Example 5

[0063] Color change properties of Zn-MOF-based fabric:

[0064] As Figure 5 shown, when the wavelength is greater than 420 nm, the K / S value of the Zn-MOF-based fabric after light irradiation is greater than that before light irradiation, and a peak appears at a wavelength of 550 nm, mainly due to the deepening of the dyeing depth, the increase in color brightness and color saturation.

[0065] Test Example 6

[0066] UV resistance of Zn-MOF-based fabric:

[0067] In the national standard, the highest specified value of UPF for textiles is 50+, which has basically no impact on the human body. As Figure 6 shown, the UPF value of the original fabric is 12.21, which is less than 50 and does not have the property of preventing ultraviolet rays. While the UPF values of the three photosensitive fabrics are all greater than 50, and they have good ultraviolet resistance. Among them, the UPF value of the layer-by-layer self-assembled fabric is as high as 159.33, and it has the best ultraviolet resistance. It can be seen that Zn-MOF and its coatings have good ultraviolet resistance after being combined with cotton fabrics. Therefore, MOFs coatings can be widely used in daily textile industries such as umbrella surfaces, tents, and clothing.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than limiting them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and 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. Application of a MOF-based fabric in both ultraviolet resistance and color-changing functions, characterized in that, The preparation of the MOF-based fabric includes the following steps: (1) Modification of cotton fabric: Immerse 0.1 g of cotton gauze in 10 mL of a solution containing 1 M sodium chloroacetate and 5% sodium hydroxide, and react under stirring at room temperature for 1 h; after the reaction, wash the carboxymethylated cotton gauze with deionized water to remove the residual reagents, and then dry it overnight at room temperature; (2) Synthesis of MOF-based fabric: ① Dissolve 0.0297 g of metal salt Zn(NO3)2·6H2O, 0.0204 g of the first ligand 1-carboxy-4',4'-bipyridine, and 16.7 mg of the second ligand terephthalic acid in a mixed aqueous solution containing DMF and methanol; ② Then soak the modified cotton fabric successively 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 bonded to the fabric surface with clean deionized water; ③ Repeat the above processes ① and ② multiple times until the cotton fabric is completely covered with the MOF material.

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