CN114990885B - Ultraviolet-resistant superhydrophobic fabric and preparation method thereof - Google Patents

Abstract

The invention discloses an ultraviolet-resistant super-hydrophobic fabric and a preparation method thereof, comprising a fabric and a nano porous metal-organic framework structure grown on the surface of the fabric in situ; the nano porous metal organic framework structure is formed by coordination and assembly of metal ions and organic ligands. The invention carries out diazo radical polymerization reaction on the surface of fiber by aromatic radical containing carboxyl to generate aromatic polymer chain containing carboxyl; and then growing a MOF structure crystal coating on the surface of the fiber in situ by a layer-by-layer self-assembly strategy, and obtaining the super-hydrophobic MOF@fabric by hydrophobization after finishing. Based on excellent characteristics of porous performance, large specific surface area and the like of the MOF structure, and the MOF crystal is connected with the surface of the fiber through covalent bonds, the MOF@fabric is endowed with excellent ultraviolet resistance and superhydrophobic performance, and the application of the MOF@fabric in the fields of anti-fouling self-cleaning and the like is expanded. The fabric finishing process is completed at room temperature, the production and preparation process is simple, the reaction condition is mild, the operation is safe, and the expansion production is easy.

Description

A kind of anti-ultraviolet superhydrophobic fabric and preparation method thereof

technical field

The invention relates to a MOF@fabric with anti-ultraviolet and super-hydrophobic functions and a preparation method thereof, belonging to the technical field of special functional textiles and its preparation.

Background technique

Many MOF materials with different organic ligands and metal ions have been developed in the prior art, and have been rapidly developed in the fields of filtration, gas storage, separation, antibacterial, energy storage, catalysis, water collection, and drug coating and sustained release. However, most of the previous studies on MOF materials were carried out in powder form, which greatly limited their practical application fields. Due to its natural advantages such as flexibility, wearability, breathability, and easy processing, textiles have extensive and important application backgrounds in the fields of actual production, life, and industrial development, such as clothing, home textiles, industrial textiles, and medical textiles. With the rapid development of modern society, the demand for textiles is increasing, especially for personalized and multifunctional textiles. Therefore, textiles with a single function can no longer meet the needs of social development. When exposed to harsh conditions, such as strong ultraviolet rays, toxic chemicals, or bacteria, traditional fabrics are not enough. Therefore, it is usually necessary to modify the fibers with functional materials to improve the protective properties of ordinary fabrics and increase their application functions.

Fabrics provide an ideal flexible platform for the loading of MOFs, and the methods of incorporating MOFs into fiber substrate materials by dipping, mixing, etc. have been reported, achieving special applications with enhanced functions and ideal large specific surface areas. However, in the MOF-fiber composites prepared by the above methods, the interaction force between MOF and fibers is poor and unstable. Therefore, the resulting final product cannot achieve the desired application effect. In addition, hydrolytic instability is also one of the major drawbacks of existing MOF materials.

Contents of the invention

The invention uses diazo radical covalent grafting polymerization method for surface modification of cellulose fiber materials, and combines the unique advantages of MOF materials, and discloses a functionalized MOF@fabric and a preparation method thereof. During the preparation, the carboxyl-containing aromatic radicals are grafted and polymerized on the surface of the fiber to form a carboxyl polymer chain brush; then, through the treatment process, the MOF is grown in situ without affecting the strength, breathability, hand feeling and wearing performance of the fabric. Crystal coating to obtain functionalized MOF@fabric. Aiming at the current problems of unsatisfactory fastness, single function, and uneven crystal growth of MOF loaded on the fiber surface, the present invention uses carboxyl aromatic free radicals to graft fibers to form carboxyl-containing polymer chain brushes on the surface of the fibers, which are MOF crystals. The growth provides sufficient active sites, thereby enhancing the MOF loading rate, durability, and endowing the fabric with multifunctionality.

The technical scheme that realizes the object of the present invention is:

An ultraviolet-proof super-hydrophobic fabric, comprising a fabric, a carboxyl aromatic polymer chain grafted on the surface of the fabric, a MOF crystal structure and a hydrophobic coating; the MOF crystal structure is formed by coordination and assembly of metal ions and organic ligands.

In the present invention, the fabric is added to the carboxyl-containing aromatic diazonium salt solution, and then a chemical reducing agent is added to perform a polymerization reaction to obtain a fabric with carboxy-aromatic polymer chains grafted on the surface; The MOF@fabric is self-assembled layer by layer in the solution and the organic ligand solution, and then the MOF@fabric is hydrophobically coated to obtain the UV-resistant superhydrophobic fabric.

In the present invention, the fabric is cotton fabric and/or hemp fabric; MOF is CuBTC.

In the present invention, the carboxyl-containing aromatic amine is diazotized in an acid solution of sodium nitrite to obtain a carboxyl-containing aromatic diazonium salt solution.

Specifically, the preparation method of the ultraviolet-proof superhydrophobic fabric of the present invention is as follows:

(1) Carboxyl-containing aromatic amines are diazotized in an acid solution of sodium nitrite to obtain a diazonium salt solution, and the acid is dilute hydrochloric acid or dilute sulfuric acid;

(2) Add the fabric to the above diazonium salt solution, and then add a reducing agent to reduce the carboxyl-containing aromatic diazonium salt to carboxyl-containing aromatic free radicals at room temperature, and the carboxyl-containing aromatic free radical monomers are free on the surface of the fiber Carboxyl aromatic polymer chains through covalent graft polymerization reaction;

(3) Dissolve metal salt in N,N-dimethylacetamide, ethanol and water to prepare metal ion solution A; dissolve organic ligand in N,N-dimethylacetamide, ethanol and water to prepare organic ligand Solution B;

(4) Add the carboxylated fabric prepared in (2) to the metal ion solution A and the organic ligand solution B prepared in (3) in sequence, and carry out self-assembly growth layer by layer to form a MOF coating structure, and the reaction is certain. Time to make MOF@fabric.

(5) Immerse the MOF@fabric prepared in (4) in siloxane, such as ethanol solution of n-octyltriethoxysilane or n-hexyltriethoxysilane for a certain period of time, and obtain functional properties after baking. Chemical MOF@fabric.

Among the present invention, carboxyl-containing aromatic amine is preferably carboxyl-containing aniline, and its chemical structural formula is as follows:

The carboxyl-containing aromatic radical has the following chemical structure:

In the above structural formula of the present invention, R ₁ is hydrogen or carboxyl. Preferably, the carboxyl group is -COOH, -CH ₂ COOH or -C ₂ H ₄ COOH.

In the present invention, the time of the polymerization reaction is 6~72h, preferably 36~48h.

In the present invention, the carboxylated fabric (that is, the fabric grafted with carboxyl aromatic polymer chains on the surface) is sequentially added to the metal ion solution and the organic ligand solution for cyclic self-assembly. 10 to 20 minutes; the number of self-assembly cycles is 3 to 30 times, preferably 10 to 15 times.

In the present invention, the hydrophobic coating finishing agent is siloxane containing hydrophobic segments, preferably n-octyltriethoxysilane or n-hexyltriethoxysilane. The invention adopts the non-fluorine-containing finishing agent to realize the superhydrophobic performance of the fabric and meet the superhydrophobic requirement that the water contact angle is greater than 150°.

The UV-resistant superhydrophobic functionalized MOF@fabric of the present invention is a modified fiber with a regular crystal structure coating on the surface, and the crystal coating gradually grows from nano-sized particles to micron-sized particles as the number of cycles increases.

In the above technical solution, in step (1), the molar concentration of the acid solution is 0.2-3M, preferably 0.8-1.5M; the diazotization is a low-temperature reaction, and the temperature is -15-25°C, preferably -5~5°C; the time for the diazotization reaction is 0.1~12h, preferably 0.5~3h.

In the above technical solution, the reducing agent is vitamin C (VC).

In the present invention, a carboxylated fabric is prepared by covalent graft polymerization between a carboxyl-containing aromatic radical free radical monomer and a natural fiber through single-electron free radical, and the coordination between a metal ion and an organic ligand is used to produce a carboxylated fabric. A roughened MOF@fabric, and a functionalized MOF@fabric was obtained by finishing with a hydrophobic coating.

The present invention specifically relates to a method for grafting and polymerizing carboxyl-containing aromatic amines through diazonium free radical covalent bonds to form carboxyl-containing polymer chain brushes on the surface of fibers; Growth metal-organic framework structure; finally, the functionalized MOF@fabric prepared by modifying the fiber surface through hydrophobic coating finishing. Compared with prior art, its beneficial effect of technical scheme provided by the present invention is:

1. The present invention carries out carboxylation and graft modification on the surface of the fiber through the method of covalent graft polymerization of aromatic diazonium radicals, forming carboxyl polymer molecular chain brushes on the fiber surface, providing carboxyl active sites, and being metal The anchoring of ions provides the necessary conditions for the growth of MOF crystals. This is of great significance for the in situ growth of MOF materials on the fiber surface to prepare a new generation of functionalized MOF fabrics.

2. The combination between carboxylated fibers and MOF crystals is stable, which endows MOF with excellent fastness to the fabric, and solves the problem of poor fastness of conventional MOF@fabric through physical mixing and adsorption. This point is of great significance for the development of a durable MOF@fabric.

3. The prepared MOF@fabric combines the soft, wearable and breathable fabric with the unique advantages of high specific surface area, porosity, and adjustable structural properties of MOF materials. The application prospect of MOF materials is of great significance.

4. The preparation method of MOF@fabric is simple, the reaction conditions are mild, easy to operate, large-scale production and easy to promote.

Description of drawings

Fig. 1 is the reaction schematic diagram of the present invention.

Figure 2 is a schematic diagram of the chemical structure of the fiber surface of the modified fabric.

Fig. 3 is the scanning electron microscope (SEM) picture of the raw cotton fabric of embodiment 1, and the surface has wrinkles, A in the figure; the scanning electron microscope (SEM) picture of the carboxyl free radical graft polymerization finishing fabric prepared in embodiment 1, The nano-scale particle structure formed by carboxyl-containing aromatic polymer chains on the surface of the fiber, B in the figure; the scanning electron microscope (SEM) image of the MOF@fabric prepared in Example 1, the regular distribution of micron octahedral crystal structure MOF coating on the fiber surface , C in the figure.

Figure 4 is the infrared spectrum and X-ray diffraction spectrum of the functionalized MOF@fabric prepared in Example 1.

Fig. 5 is the ultraviolet transmission and absorption curve test chart of the unmodified raw cotton fabric, carboxylated modified cotton fabric, MOF @ fabric and superhydrophobic MOF @ fabric of Example 1, and the UPF values of the measured fabrics are 20.9 ± 3.2, 45.9 respectively ± 6.6, 199.5 ± 14.7, 192.2 ± 13.2.

Fig. 6 is the contact angle test figure of embodiment one unmodified raw cotton fabric, and the surface contact angle that records fabric is respectively 0 °, figure A; The contact angle test figure of embodiment one carboxylation modified cotton fabric, records The surface contact angle of fabric is respectively 0 °, Fig. B; The contact angle test figure of embodiment one MOF@fabric, the surface contact angle of recording fabric is respectively 0°, Fig. C; The contact of embodiment one hydrophobic MOF@fabric Angle test chart, the measured surface contact angle of the fabric is 168.4 ± 1.6°, Figure D.

Figure 7 is a scanning electron microscope (SEM) image of the MOF@fabric prepared in Example 2. The surface of the fiber is coated with MOF containing a micron octahedral crystal structure.

Figure 8 is a scanning electron microscope (SEM) image of the MOF@fabric prepared in Example 3. The surface of the fiber is coated with MOF containing a micron octahedral crystal structure.

Figure 9 is a scanning electron microscope (SEM) image of the non-carboxylated modified fabric long MOF prepared in Comparative Example 1, and a small amount of irregular micro-nano crystal structure particles are distributed on the surface of the fiber.

Detailed ways

Fabrics provide an ideal flexible platform for the loading of MOFs, and the methods of incorporating MOFs into fiber substrate materials by dipping, mixing, etc. have been reported, achieving special applications with enhanced functions and ideal large specific surface areas. However, in the MOF-fiber composites prepared by the above methods, the interaction force between MOF and fibers is poor and unstable. Therefore, the resulting final product cannot achieve the desired application effect. In addition, hydrolytic instability is also one of the major drawbacks of existing MOF materials. In order to solve these problems, the present invention integrates MOF materials into fibers through a new method, providing a feasible solution for the development of MOF@fabrics in the future.

Taking carboxyl-containing aniline as an example, the present invention discloses the preparation method of the above-mentioned MOF@fabric, which includes the following steps:

(1) Carboxylated aniline is diazotized in dilute acid solution of sodium nitrite to form diazonium salt;

(2) The carboxyl-containing benzene diazonium salt is converted into carboxyl-containing benzene radicals under the action of a reducing agent; the carboxyl-containing benzene radical monomers and the oxygen radicals on natural fibers undergo in-situ single-electron free-radical covalent graft polymerization reaction;

(3) The metal ions are anchored on the surface of the fiber through the coordination with the carboxyl group, and then through layer-by-layer self-assembly with the metal ion solution A, ethanol, and organic ligand solution B, in situ on the fiber surface Growth forms the MOF coating structure.

(4) Use hydrophobic substances to coat MOF@fabric to obtain functionalized MOF@fabric.

See Figure 1 for the reactions involved. Add sodium nitrite into the dilute acid solution under low temperature and stir to dissolve to form sodium nitrite acid solution, then add carboxyl-containing aniline into the above-mentioned sodium nitrite acid solution and stir for diazotization reaction to generate carboxyl-containing benzene diazonium salt; Add the reducing agent into the above-mentioned diazonium salt solution, raise the reaction temperature to room temperature, reduce the diazonium salt containing carboxyl benzene to the monomer containing carboxyl benzene free radical, and release nitrogen; In the solution, the carboxyl-containing benzene free radical monomer initiates single-electron free radicals on its hydroxyl groups on the cellulose fibers to generate oxygen free radicals. After adding VC, other carboxyl-containing benzene free radical monomers react with the oxygen free radicals on the cellulose fibers Carboxyl aromatic polymer chains are formed on the surface of the fiber through in-situ free radical covalent graft polymerization for a certain period of time; first, add the carboxylated fabric to the metal ion solution A for a certain period of time, then put it into the ethanol solution for cleaning for 10 seconds, and then Then add the above-mentioned fabric to the organic ligand solution B, and then put it into the ethanol solution for cleaning for 10 seconds. The above-mentioned process is a cycle; the above-mentioned operation process is continuously cycled, and finally a dense MOF crystal coating is formed on the surface of the fiber. Then the MOF@fabric was immersed in the ethanol solution of the hydrophobic substance for a certain period of time, and the functionalized MOF@fabric was obtained after baking.

The invention carries out graft copolymerization on cellulose-based fibers of cotton, hemp and other fabrics, and uses the carboxyl active sites on the surface of the fibers, and the coordination between Cu ²⁺ and organic ligands to grow in situ on the surface of the fibers to construct the MOF crystal structure , the chemical structure of the fiber surface of the modified fabric is shown in Figure 2, where n=3-100 is the structure of fabric cellulose, which is common sense; m=1-50.

The technical solution of the present invention will be further described below in conjunction with the accompanying drawings and examples. The raw materials involved are conventional commodities, and the raw cotton fabric is a hydrophilic fabric with a size of 5cm×8cm; the specific preparation operation and testing are conventional techniques, and if there is no special instruction, The experiment was carried out in air.

Embodiment one

(1) Generate diazonium salt of m-aminobenzoic acid

The round bottom flask was equipped with a thermometer and equipped with magnetic stirring. Add 60 ml of 1M hydrochloric acid solution, cool to 15°C in a cold bath, add 3.3 mmol of sodium nitrite, cool to -5°C in a cold bath, stir and dissolve to form a sodium nitrite hydrochloric acid solution. Then add 3 mmol of m-aminobenzoic acid and keep diazotization for 1 h to generate m-carboxybenzoic acid diazonium salt solution.

(2) Generate m-carboxybenzene radicals

Add a piece of cotton fabric to the above diazonium salt solution, then add 53mg of reducing agent VC, the temperature of the reaction solution is raised to room temperature and kept for 36 hours, m-carboxybenzoic acid diazonium salt is reduced to m-carboxybenzene free radical monomer, and simultaneously releases Nitrogen; m-carboxybenzene radical monomers cause homolysis of hydroxyl groups on cotton fibers to generate oxygen free radicals, while other m-carboxybenzene radical monomers continue to undergo in-situ free radical covalent bonding with oxygen free radicals on cotton fibers The branches are polymerized to form carboxylated aromatic polymer chain brushes, which are called carboxylated cotton fabrics.

(3) Dissolve 3.8g Cu(NO ₃ ) ₂ ·3H ₂ O in 48 mL of N,N-dimethylacetamide, ethanol and water at a ratio of 1:1:1 to prepare a solution containing metal ions A; 1.35 g of 1,3,5-benzenetricarboxylic acid was dissolved in 48 mL of N,N-dimethylacetamide, ethanol and water in a mixed solvent with a ratio of 1:1:1 to prepare an organic ligand solution B .

(4) Immerse a piece of 5cm×8cm carboxylated cotton fabric in solution A containing metal ions for 15 minutes, take it out and put it in ethanol solution for cleaning for 10 seconds, take it out and put it in solution B containing organic ligands for 15 minutes, then take it out and put it again Wash in ethanol solution for 10s; the above operation steps are a cycle process, and then cycle this process 10 times. Finally, the sample was taken out and shaken and washed in 50 mL of new absolute ethanol solution, repeated 5 times to remove the remaining unbound metal ions and organic ligands, and finally dried in an oven at 50 °C for 3 hours to obtain MOF@fabric.

(5) The MOF@fabric obtained in (4) was immersed in 20mL of n-octyltriethoxysilane methanol solution for 1h, and then the fabric was taken out and baked at 140°C for 1h to obtain a hydrophobized MOF@fabric.

(6) UV resistance test

The UV-2000F textile sun protection index analyzer of Labsphere Co., Ltd. was used to test the UV resistance UPF value of the fabric before and after modification according to GB/T18830. Each single-layer fabric sample was tested five times to get the average value. The measured UPF values of unmodified raw cotton fabric, carboxylated modified cotton fabric, MOF@fabric and superhydrophobic MOF@fabric were 20.9 ± 3.2, 45.9 ± 6.6, 199.5 ± 14.7, 192.2 ± 13.2, respectively. It shows that the modified MOF@fabric exhibits very excellent anti-ultraviolet properties.

(7) Contact angle test

The DSA100 automatic microscopic droplet wettability tester of German Krüss company was used to test the wettability of MOF@fabric before and after modification. Deionized water was selected as the test droplet, and the droplet volume was 5 μL, and the test was taken five times respectively. its average. The surface contact angles of unmodified raw cotton fabrics, carboxylated modified cotton fabrics, MOF fabrics and hydrophobized MOF fabrics were measured to be 0°, 0°, 0° and 168.4 ± 1.6°, respectively, indicating that the unmodified raw cotton fabrics , Carboxylated modified cotton fabric, and MOF@fabric exhibited superhydrophilic properties, while MOF@fabric exhibited superhydrophobic properties after hydrophobic modification.

Fig. 3 is the scanning electron microscope (SEM) picture of the raw cotton fabric of embodiment 1, and the surface has wrinkles, A in the figure; the scanning electron microscope (SEM) picture of the carboxyl free radical graft polymerization finishing fabric prepared in embodiment 1, The nano-scale particle structure formed by carboxyl-containing aromatic polymer chains on the surface of the fiber, B in the figure; the scanning electron microscope (SEM) image of the MOF@fabric prepared in Example 1, the regular distribution of micron octahedral crystal structure MOF coating on the fiber surface , C in the figure.

Figure 4 is the infrared spectrum and X-ray diffraction spectrum of the functionalized MOF@fabric fabric prepared in Example 1.

Fig. 5 is the ultraviolet transmission and absorption curve test chart of the unmodified raw cotton fabric, carboxylated modified cotton fabric, MOF @ fabric and superhydrophobic MOF @ fabric of Example 1, and the UPF values of the measured fabrics are 20.9 ± 3.2, 45.9 respectively ± 6.6, 199.5 ± 14.7, 192.2 ± 13.2.

Fig. 6 is the contact angle test figure of embodiment one unmodified raw cotton fabric, and the surface contact angle that records fabric is respectively 0 °, figure A; The contact angle test figure of embodiment one carboxylation modified cotton fabric, records The surface contact angle of fabric is respectively 0 °, Fig. B; The contact angle test figure of embodiment one MOF@fabric, the surface contact angle of recording fabric is respectively 0°, Fig. C; The contact of embodiment one hydrophobic MOF@fabric Angle test chart, the measured surface contact angle of the fabric is 168.4 ± 1.6°, Figure D.

If the above Cu(NO ₃ ) ₂ ·3H ₂ O is replaced by Co(NO ₃ ) ₂ ·6H ₂ O, and the rest remains unchanged, the UPF value of the obtained MOF@fabric is 91.9±10.2.

Embodiment two

(1) Generate diazonium salt of m-aminobenzoic acid

The round bottom flask was equipped with a thermometer and equipped with magnetic stirring. Add 60 ml of 1M hydrochloric acid solution, cool to 15°C in a cold bath, add 3.3 mmol of sodium nitrite, cool to -5°C in a cold bath, stir and dissolve to form a sodium nitrite hydrochloric acid solution. Then add 3 mmol of triaminobenzoic acid and keep diazotization for 1 h to generate m-carboxybenzoic acid diazonium salt solution.

(2) Generate m-carboxybenzene radicals

Add a piece of cotton fabric to the above diazonium salt solution, then add 53mg of reducing agent VC, the temperature of the reaction solution is raised to room temperature and kept for 36 hours, m-carboxybenzoic acid diazonium salt is reduced to m-carboxybenzene free radical monomer, and simultaneously releases Nitrogen; m-carboxybenzene radical monomers cause homolysis of hydroxyl groups on cotton fibers to generate oxygen free radicals, while other m-carboxybenzene radical monomers continue to undergo in-situ free radical covalent bonding with oxygen free radicals on cotton fibers The branches are polymerized to form carboxylated aromatic polymer chain brushes, which are called carboxylated cotton fabrics.

(3) Dissolve 3.8g Cu(NO ₃ ) ₂ ·3H ₂ O in 48 mL of N,N-dimethylacetamide, ethanol and water at a ratio of 1:1:1 to prepare a solution containing metal ions A; 1.35 g of 1,3,5-benzenetricarboxylic acid was dissolved in 48 mL of N,N-dimethylacetamide, ethanol and water in a mixed solvent with a ratio of 1:1:1 to prepare an organic ligand solution B .

(4) Immerse a piece of 5cm×8cm carboxylated cotton fabric in solution A containing metal ions for 15 minutes, take it out and put it in ethanol solution for cleaning for 10 seconds, take it out and put it in solution B containing organic ligands for 15 minutes, then take it out and put it again Wash in ethanol solution for 10s; the above operation steps are a cycle process, and then cycle this process 20 times. Finally, the sample was taken out and shaken and washed in 50 mL of new absolute ethanol solution, repeated 5 times to remove the remaining unbound metal ions and organic ligands, and finally dried in an oven at 50 °C for 3 hours to obtain MOF@fabric.

(5) The MOF@fabric obtained in (4) was immersed in 20mL of n-octyltriethoxysilane methanol solution for 1h, and then the fabric was taken out and baked at 140°C for 1h to obtain a hydrophobized MOF@fabric.

(6) UV resistance test

The UV-2000F textile sun protection index analyzer of Labsphere Co., Ltd. was used to test the UV resistance UPF value of the modified fabric according to GB/T18830. Each single-layer fabric sample was tested five times to get the average value. It is measured that the UPF value of the finished fabric is 322.6 ± 6.0, which shows very excellent anti-ultraviolet performance after modification.

(7) Contact angle test

The DSA100 automatic microscopic droplet wettability tester of German Krüss company was used to test the wettability of MOF@fabric after hydrophobic modification. Deionized water was selected as the test droplet, and the droplet volume was 5 μL. take its average value. The surface contact angles of MOF@fabric after hydrophobization modification were measured to be 169.2 ± 1.7°, indicating that MOF@fabric after hydrophobization modification exhibited excellent superhydrophobicity. In particular, the present invention solves the technical defect that the prior art requires the use of fluorine-containing materials to obtain super-hydrophobicity, and uses fluorine-free silane to achieve very good hydrophobic performance.

Fig. 7 is a scanning electron microscope (SEM) image of the MOF@fabric prepared in Example 2. The surface of the fiber is coated with MOF containing a micron-scale regular octahedral crystal structure.

Embodiment three

(1) Generate diazonium salt of 5-aminoisophthalic acid

The round bottom flask was equipped with a thermometer and equipped with magnetic stirring. Add 60 ml of 1M hydrochloric acid solution, cool to 15°C in a cold bath, add 3.3 mmol of sodium nitrite, cool to 0°C in a cold bath, stir and dissolve to form a sodium nitrite hydrochloric acid solution. Then add 3mmol of 5-aminoisophthalic acid and keep diazotization for 1h to generate dicarboxybenzenediazonium salt.

(2) Generate dicarboxybenzene radicals

Add a piece of cotton fabric to the above-mentioned diazonium salt solution, then add 53 mg of reducing agent VC, the temperature of the reaction solution is raised to room temperature and kept for 36 hours, the dicarboxybenzene diazonium salt is reduced to dicarboxybenzene radical monomer, and nitrogen gas is released at the same time ; Dicarboxybenzene radical monomers cause homolysis of hydroxyl groups on cotton fibers to generate oxygen free radicals, while other dicarboxybenzene radical monomers continue to covalently graft in-situ free radicals with oxygen free radicals on cotton fibers Polymerized to form carboxy aromatic polymer chain brushes.

(3) Dissolve 3.8g Cu(NO ₃ ) ₂ ·3H ₂ O in 48 mL of N,N-dimethylacetamide, ethanol and water at a ratio of 1:1:1 to prepare a solution containing metal ions A; 1.35 g of 1,3,5-benzenetricarboxylic acid was dissolved in 48 mL of N,N-dimethylacetamide, ethanol and water in a mixed solvent with a ratio of 1:1:1 to prepare an organic ligand solution B .

(4) Immerse a piece of 5cm×8cm carboxylated cotton fabric in solution A containing metal ions for 15 minutes, take it out and put it in ethanol solution for cleaning for 10 seconds, take it out and put it in solution B containing organic ligands for 15 minutes, then take it out and put it again Wash in ethanol solution for 10s; the above operation steps are a cycle process, and then cycle this process 10 times. Finally, the sample was taken out and shaken and washed in 50 mL of new absolute ethanol solution, repeated 5 times to remove the remaining unbound metal ions and organic ligands, and finally dried in an oven at 50 °C for 3 hours to obtain MOF@fabric.

(5) The MOF@fabric obtained in (4) was immersed in 20mL of n-octyltriethoxysilane methanol solution for 1h, and then the fabric was taken out and baked at 140°C for 1h to obtain a hydrophobized MOF@fabric.

(6) UV resistance test

The UV-2000F textile sun protection index analyzer of Labsphere Co., Ltd. was used to test the UPF value of the anti-ultraviolet performance of the fabric after finishing according to GB/T18830. Each single-layer fabric sample was tested five times to get the average value. It is measured that the UPF value of MOF@fabric after finishing is 222.6 ± 21.0, and it shows very excellent anti-ultraviolet performance after modification.

(7) Contact angle test

The DSA100 automatic microscopic droplet wettability tester of German Krüss company was used to test the wettability of MOF@fabric after hydrophobic modification. Deionized water was selected as the test droplet, and the droplet volume was 5 μL. take its average value. The surface contact angles of MOF@fabric after hydrophobization modification were measured to be 167.6 ± 2.1°, indicating that MOF@fabric after hydrophobization modification exhibited excellent superhydrophobicity.

Fig. 8 is a scanning electron microscope (SEM) image of the MOF@fabric prepared in Example 3. The surface of the fiber is coated with MOF containing a micron-scale regular octahedral crystal structure.

Comparative example one

(1) Dissolve 3.8g Cu(NO ₃ ) ₂ ·3H ₂ O in 48 mL of N,N-dimethylacetamide, ethanol and water at a ratio of 1:1:1 to prepare a solution containing metal ions A; 1.35 g of 1,3,5-benzenetricarboxylic acid was dissolved in 48 mL of N,N-dimethylacetamide, ethanol and water in a mixed solvent with a ratio of 1:1:1 to prepare an organic ligand solution B .

(2) Immerse a piece of 5cm×8cm non-carboxylated raw cotton fabric in solution A containing metal ions for 15 minutes, take it out and wash it in ethanol solution for 10 seconds, take it out and put it in solution B containing organic ligands for 15 minutes , and then take it out and put it into the ethanol solution for cleaning for 10s; the above operation steps are a cycle process, and then cycle this process 10 times. Finally, the sample was taken out and shaken and washed in 50 mL of new absolute ethanol solution, repeated 5 times to remove the remaining unbound metal ions and organic ligands, and finally dried in an oven at 50°C for 3 hours to obtain the sample.

(3) The MOF@fabric obtained in (2) was immersed in 20 mL of n-octyltriethoxysilane methanol solution for 1 hour, and then the fabric was taken out and baked at 140°C for 1 hour to obtain a hydrophobic MOF@fabric.

(4) UV resistance test

The UV-2000F textile sun protection index analyzer of Labsphere Co., Ltd. was used to test the UPF value of the anti-ultraviolet performance of the fabric after finishing according to GB/T18830. Each single-layer fabric sample was tested five times to get the average value. The measured UPF value of the finished fabric is 46.8 ± 2.2, showing general anti-ultraviolet performance.

(5) Contact angle test

The DSA100 automatic microscopic droplet wettability tester of German Krüss company was used to test the wettability of MOF@fabric after hydrophobic modification. Deionized water was selected as the test droplet, and the droplet volume was 5 μL. take its average value. The surface contact angles of MOF@fabric after hydrophobization modification were measured to be 129.2 ± 1.1°, indicating that MOF@fabric after hydrophobization modification showed general hydrophobic properties, but did not achieve superhydrophobic effect.

Fig. 9 is a scanning electron microscope (SEM) image of the non-carboxylated modified fabric long MOF prepared in Comparative Example 1.

Comparative example two

(1) Add raw cotton fabric (5cm×8cm) to the aqueous solution containing 4wt% citric acid and 4wt% sodium hypophosphite, soak for 5 minutes, dip and roll twice, then heat at 100°C for 3 minutes, then heat at 170°C After 3 minutes, a carboxylated cotton fabric was obtained.

(2) Dissolve 3.8g Cu(NO ₃ ) ₂ ·3H ₂ O in 48 mL of N,N-dimethylacetamide, ethanol and water at a ratio of 1:1:1 to prepare a solution containing metal ions A; 1.35 g of 1,3,5-benzenetricarboxylic acid was dissolved in 48 mL of N,N-dimethylacetamide, ethanol and water in a mixed solvent with a ratio of 1:1:1 to prepare an organic ligand solution B .

(3) Immerse a piece of 5cm×8cm carboxylated cotton fabric in solution A containing metal ions for 15 minutes, take it out and wash it in ethanol solution for 10 seconds, take it out and put it in solution B containing organic ligands for 15 minutes, then take it out and put it in solution again Wash in ethanol solution for 10s; the above operation steps are a cycle process, and then cycle this process 20 times. Finally, the sample was taken out and shaken and washed in 50 mL of new absolute ethanol solution, repeated 5 times to remove the remaining unbound metal ions and organic ligands, and finally dried in an oven at 50 °C for 3 hours to obtain MOF@fabric.

(4) Immerse the MOF@fabric obtained in (5) in 20mL of n-octyltriethoxysilane methanol solution for 1h, then take out the fabric and bake it at 140°C for 1h to obtain the hydrophobic MOF@fabric instead of supernatant. Hydrophobic fabric.

(5) UV resistance test

The UV-2000F textile sun protection index analyzer of Labsphere Co., Ltd. was used to test the UV resistance UPF value of the modified fabric according to GB/T18830. Each fabric sample was tested five times to get the average value, and the UPF value of MOF@fabric was measured to be 96.6 ± 8.7.

In the present invention, the fiber surface is carboxylated and modified by covalent graft polymerization of aromatic diazonium radicals, and carboxyl polymer chain brushes are formed on the fiber surface, and then through the coordination between metal ions and organic ligands, Self-assembly is carried out, and a dense MOF crystal structure coating is grown in situ on the surface of the fiber, as shown in Figure 4, which solves the problem that the fiber cannot grow MOF in situ and the sparse loading of the grown MOF crystal is small. This is of great significance for the in situ growth of MOF materials on the surface of fibers to prepare a new generation of functionalized MOF@fabrics. The invention discloses a functionalized MOF@fabric and a preparation method thereof. Carboxyaniline is used as a reactive monomer, and diazotization is carried out in an acid solution of sodium nitrite to generate a carboxyl-containing benzene diazonium salt; the fabric is added to the above-mentioned diazonium salt solution, and then a reducing agent is added, and the temperature is raised to room temperature. Under the conditions, the carboxyl-containing benzene diazonium salt is reduced to the carboxyl-containing benzene free radical, and the free radical monomer initiates single-electron free radicals on the hydroxyl groups on the surface of cellulose fiber fabrics such as cotton and hemp to generate hydroxyl free radicals; then the free radical monomer Free radical covalent grafting polymerization occurs on the surface of the fiber; the carboxylated fabric is sequentially added to the metal ion solution A, ethanol, organic ligand solution B, and ethanol, and self-assembles and grows layer by layer to form a MOF coating structure. The MOF@fabric is prepared for a certain period of time; then it is treated with a hydrophobic coating to finally obtain a superhydrophobic MOF@fabric. The carboxylated fabric treatment process of the present invention is completed by reducing polymerization with a chemical reducing agent in dilute acid solution at room temperature, and the in-situ growth of MOF is also completed at room temperature, with simple production process, mild reaction conditions and safe operation. Based on the carboxyl-containing aromatic polymer chains covalently bonded on the surface of the fiber, and the carboxyl active sites provide sufficient conditions for the anchoring of a large number of metal ions and the in-situ growth of MOF; making functional fabrics with strong UV absorption and super-hydrophobic properties without affecting the original wearability of the fabric; the present invention solves the problem of poor fastness and small load of MOF@fabric obtained through mechanical mixing and finishing, and at the same time endows the fabric with more valuable additional functions application potential. The carboxylated fabric treatment is completed by aromatic radical polymerization, and the MOF crystals are grown in situ through layer-by-layer self-assembly. Combined with the unique properties of the metal-organic framework MOF porous structure, functionalized MOF@fabric is obtained.

Claims (10)

1. a kind of anti-ultraviolet super-hydrophobic fabric, it is characterized in that: described anti-ultraviolet super-hydrophobic fabric comprises the carboxyl aromatic polymer chain of fabric, fabric surface grafting, MOF crystal structure and hydrophobic coating; Described MOF crystal structure is made of metal Formed by coordination and assembly of ions and organic ligands; the preparation method of the UV-resistant superhydrophobic fabric is that the fabric is added to a carboxyl aromatic diazonium salt solution, and then a chemical reducing agent is added, and the polymerization reaction is carried out to obtain a surface-grafted carboxyl aromatic polymer Chain fabric; then the fabric grafted with carboxyl aromatic polymer chains on the surface is self-assembled layer by layer in a solution containing metal ions and organic ligands to obtain an anti-ultraviolet fabric; finally, the anti-ultraviolet superhydrophobic fabric is obtained by hydrophobic finishing ; MOF is CuBTC. 2. according to the described anti-ultraviolet superhydrophobic fabric of claim 1, it is characterized in that, fabric is cotton fabric and/or hemp fabric. 3. according to the preparation method of the described anti-ultraviolet superhydrophobic fabric of claim 1, it is characterized in that, fabric is added in containing carboxyl aromatic diazonium salt solution, then add chemical reductant, polymerization reaction obtains surface grafted carboxyl aromatic polymer chain Then the fabric grafted with carboxyl aromatic polymer chains on the surface is self-assembled layer by layer in a solution containing metal ions and an organic ligand to obtain an anti-ultraviolet fabric; finally, the anti-ultraviolet ultra-hydrophobic fabric is obtained through hydrophobic finishing. 4. according to the preparation method of the described anti-ultraviolet superhydrophobic fabric of claim 3, it is characterized in that, carry out diazotization in the acid solution of sodium nitrite containing carboxyl aromatic amine, obtain containing carboxyl aromatic diazonium salt solution; The polymerization reaction time is 6~72h. 5. according to the preparation method of the described anti-ultraviolet superhydrophobic fabric of claim 3, it is characterized in that, the fabric of surface grafted carboxyl aromatic polymer chain is immersed in the solution containing metal ion again in organic ligand solution again, to self-assemble. 6. The preparation method of the ultraviolet-proof super-hydrophobic fabric according to claim 5, characterized in that, the soaking time is 3-60 minutes; the number of times of layer-by-layer self-assembly is 3-30 times. 7. according to the preparation method of the described anti-ultraviolet superhydrophobic fabric of claim 3, it is characterized in that, utilize siloxane to carry out hydrophobic finishing. 8. An anti-ultraviolet fabric, characterized in that, the anti-ultraviolet fabric comprises a carboxyl aromatic polymer chain grafted on the surface of the fabric, a fabric, and a MOF crystal structure; the MOF crystal structure is assembled by coordination of metal ions and organic ligands Formation; the preparation method of the UV-resistant fabric is that the fabric is added to the carboxyl-containing aromatic diazonium salt solution, and then a chemical reducing agent is added to perform a polymerization reaction to obtain a fabric with carboxyl aromatic polymer chains grafted on the surface; then the surface is grafted with carboxyl groups The fabric of the aromatic polymer chain is self-assembled layer by layer in a solution containing metal ions and an organic ligand to obtain an anti-ultraviolet fabric; the MOF is CuBTC. 9. The anti-ultraviolet fabric according to claim 8, characterized in that the fabric grafted with carboxyl aromatic polymer chains on the surface is immersed in a solution containing metal ions and then immersed in an organic ligand solution to carry out self-assembly. 10. according to claim 1 described anti-ultraviolet superhydrophobic fabric or the application in the described anti-ultraviolet fabric of claim 8 in the preparation functional fabric.