Radiation refrigeration fabric and preparation method thereof

Abstract

The invention discloses a radiation refrigeration fabric and a preparation method thereof, and belongs to the technical field of fabric materials. The radiation refrigeration fabric comprises a substrate and a radiation refrigeration layer arranged on the substrate, raw materials of the radiation refrigeration layer are composed of modified polyvinyl alcohol and oxygen vacancy-containing zinc oxide, the modified polyvinyl alcohol is prepared from polyvinyl alcohol and medium-long chain saturated monoaldehyde under the catalytic action of p-toluenesulfonic acid monohydrate, and the modified polyvinyl alcohol is prepared from modified polyvinyl alcohol and medium-long chain saturated monoaldehyde under the catalytic action of p-toluenesulfonic acid monohydrate. The mass ratio of the polyvinyl alcohol to the medium and long chain saturated monoaldehyde to the p-toluenesulfonic acid monohydrate is 1: (1-1.4): (0.07-0.11); according to the invention, polyvinyl alcohol is reasonably modified, an oxygen vacancy structure of zinc oxide is precisely regulated and controlled, and an efficient synergistic effect system is successfully constructed by combining the matching ratio design of polyvinyl alcohol and zinc oxide, so that the prepared radiation refrigeration fabric has excellent comprehensive performance.

Description

Technical Field

[0001] This invention belongs to the field of textile materials technology, specifically relating to a radiation-cooling fabric and its preparation method. Background Technology

[0002] Against the backdrop of intensifying global warming and frequent extreme heat events, the cooling performance of fabrics has become a core element in improving clothing comfort and reducing social energy consumption. Traditional fabrics mostly rely on physical barriers or moisture wicking to regulate temperature, but in high-temperature environments, their heat dissipation efficiency is significantly limited, making it difficult to effectively maintain the body's thermal balance—especially in high-intensity scenarios such as outdoor work and sports, which can easily lead to overheating, heatstroke, and other safety hazards.

[0003] To address this problem, radiation cooling technology has become a research hotspot. This technology utilizes the infrared radiation emitted by the material itself in the 8-13μm wavelength band to directly dissipate heat into the low-temperature outer space, achieving passive cooling without consuming additional energy. It possesses significant technological advantages such as energy saving, environmental protection, and continuous stability. However, existing radiation-cooled fabrics generally face a prominent challenge: it is difficult to simultaneously achieve both cooling performance and mechanical durability.

[0004] Existing radiation-cooling fabrics often employ nanoparticle doping and photonic crystal structure design to construct functional layers. For example, coatings containing nanoparticles such as titanium dioxide and silicon dioxide are used to enhance sunlight reflection through the Mie scattering effect; or periodic structural fibers are woven to form photonic crystals for spectral modulation. However, these functional layers are brittle and have weak adhesion to the substrate, making them prone to detachment and damage during daily use due to friction, stretching, and washing, leading to a sharp drop in cooling performance. Increasing the substrate thickness or selecting high-strength fibers to improve durability, however, reduces sunlight reflection due to enhanced fiber optical absorption, further decreasing cooling efficiency. This contradiction limits their application scenarios and lifespan, hindering industrial development. Therefore, developing new fabrics that combine excellent cooling performance with durability is of great significance. Summary of the Invention

[0005] The purpose of this invention is to provide a radiation cooling fabric to solve the problem that existing radiation cooling fabrics are difficult to balance cooling performance and mechanical durability.

[0006] The purpose of this invention is to provide a method for preparing a radiation-cooled fabric, which is used to prepare the aforementioned radiation-cooled fabric.

[0007] The objective of this invention can be achieved through the following technical solutions: A radiation-cooling fabric includes a substrate and a radiation-cooling layer disposed on the substrate, wherein the raw materials of the radiation-cooling layer include modified polyvinyl alcohol and zinc oxide containing oxygen vacancies. The modified polyvinyl alcohol is prepared by polyvinyl alcohol and medium- and long-chain saturated monohydric aldehyde under the catalysis of p-toluenesulfonic acid monohydrate, and the mass ratio of polyvinyl alcohol, medium- and long-chain saturated monohydric aldehyde and p-toluenesulfonic acid monohydrate is 1:(1-1.4):(0.07-0.11).

[0008] Furthermore, the substrate is any one or more of cellulose-based fabrics, polyester fabrics, and polypropylene fabrics.

[0009] Furthermore, the mass ratio of the modified polyvinyl alcohol to the oxygen-vacant zinc oxide is 1:(0.2-0.4).

[0010] Furthermore, the modified polyvinyl alcohol and the zinc oxide containing oxygen vacancies are independently distributed on the surface and inside the radiation cooling layer, respectively.

[0011] Furthermore, the medium-to-long chain saturated monohydric aldehyde is any one or more of the saturated monohydric aldehydes with 4-10 carbon atoms.

[0012] Furthermore, the medium- and long-chain saturated monoaldehyde is any one or more of butyraldehyde, pentanaldehyde, hexanal, heptaldehyde, octanaldehyde, nonanaldehyde, and decanaldehyde, preferably octanaldehyde.

[0013] Furthermore, the preparation method of the modified polyvinyl alcohol includes the following steps: A1. Polyvinyl alcohol and dimethyl sulfoxide are placed in a glass container and heated to 90°C to dissolve them, thus obtaining a polyvinyl alcohol solution; A2. Cool the obtained polyvinyl alcohol solution to 60°C, add p-toluenesulfonic acid monohydrate, and stir for 1 hour to obtain an acidified polyvinyl alcohol solution; A3. Add medium- to long-chain saturated monohydric aldehydes dropwise to an acidified polyvinyl alcohol solution and react for 1-3 hours to obtain reaction mixture A; A4. Pour reaction mixture A into a saturated sodium bicarbonate solution, stir, and allow precipitation. Wash and dry the precipitate to obtain modified polyvinyl alcohol.

[0014] The above reaction mainly utilizes the aldol reaction mechanism, that is, under acidic conditions, the aldehyde oxygen atom of the medium-to-long chain saturated monohydric aldehyde reacts with a proton (H). + The two groups combine to form a protonated aldehyde intermediate, which significantly enhances the positive charge of the aldehyde carbon and improves its electrophilic activity. Subsequently, the two adjacent hydroxyl groups in the polyvinyl alcohol molecule act as nucleophiles. The oxygen atom of one of the hydroxyl groups attacks the electron-deficient carbon of the protonated aldehyde, resulting in nucleophilic addition and forming a hemiacetal intermediate. Then, under acidic conditions, the hemiacetal intermediate further reacts with the other hydroxyl group of the polyvinyl alcohol. Through proton transfer and dehydration, a stable cyclic acetal structure is finally formed. The alkane side chain of the medium-to-long chain saturated monohydric aldehyde is linked to the polyvinyl alcohol molecular chain through an acetal bond, resulting in modified polyvinyl alcohol.

[0015] Furthermore, the ratio of polyvinyl alcohol to dimethyl sulfoxide is 1 g:(30-50) mL.

[0016] Furthermore, the zinc oxide containing oxygen vacancies is obtained by heat treatment of Zn(OH)2 in air at 400°C and hydrogen at 400°C, respectively.

[0017] Furthermore, the heat treatment time in the air is 2-4 hours.

[0018] Furthermore, the heat treatment time in the hydrogen gas is 1-3 hours.

[0019] Furthermore, the thickness of the radiation cooling layer is 40-200 μm.

[0020] A method for preparing a radiation-cooling fabric includes the following steps: S1. Modified polyvinyl alcohol is added to N,N-dimethylformamide (DMF) and stirred at 90°C for 6-10 hours. After stirring, zinc oxide containing oxygen vacancies is added and ultrasonically dispersed to obtain a dispersion. S2. Coat the dispersion onto the substrate surface and place it in saturated water vapor at room temperature for 24-48 hours. After the placement is completed, wash and soak it with deionized water, and then dry it to obtain the radiation cooling fabric.

[0021] Furthermore, the ratio of the modified polyvinyl alcohol to DMF is (14-16) g: 100 mL.

[0022] The beneficial effects of this invention are: 1. This invention utilizes the synergistic effect between modified polyvinyl alcohol and zinc oxide with oxygen vacancies to successfully construct a closed-loop "emission-reflection" system. The cyclic acetal structure of the modified polyvinyl alcohol directionally enhances infrared emission in the 8-13μm atmospheric window through molecular vibrations of medium- and long-chain alkane side chains. Meanwhile, the zinc oxide with oxygen vacancies not only blocks heat input with its high solar reflectivity, but its defective structure also broadens the infrared response range, forming a complementary coverage with the emission band of the modified polyvinyl alcohol, significantly improving the cooling performance of the radiation-cooling fabric.

[0023] 2. In this invention, the modified polyvinyl alcohol can not only form hydrogen bonds or van der Waals forces with the hydroxyl groups of the base fiber, but also anchor the zinc oxide containing oxygen vacancies through surface interactions, thereby improving the stability of the zinc oxide containing oxygen vacancies in the radiation cooling layer. During friction, the film structure of the modified polyvinyl alcohol can disperse stress, while the zinc oxide particles can act as "wear-resistant fulcrums" to reduce local losses. During the folding process, the synergistic deformation of the flexible film and rigid particles can prevent cracks from forming. This comprehensive protection mechanism significantly improves the durability of the radiation cooling fabric.

[0024] 3. This invention utilizes medium- and long-chain saturated monohydric aldehydes to modify polyvinyl alcohol, successfully introducing long-chain alkane side chains into its structure. The introduction of this structure increases the surface energy barrier of the fabric, making it difficult for water droplets to spread on the surface, thus giving the fabric good hydrophobicity. This hydrophobicity not only reduces the interference of humid environments on infrared emission, but also endows the fabric with self-cleaning ability. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. The polyvinyl alcohol used in the following examples was purchased from Sigma-Aldrich and has a molecular weight of 89,000-98,000. Other materials and reagents used in the following examples are commercially available unless otherwise specified.

[0027] Preparation Example 1

[0028] A modified polyvinyl alcohol is prepared according to the following method: A1. Place 5g of polyvinyl alcohol and 200mL of dimethyl sulfoxide in a round-bottom flask and heat at 90℃ to dissolve them, thus obtaining a polyvinyl alcohol solution. A2. Cool the obtained polyvinyl alcohol solution to 60°C, add 0.45g of p-toluenesulfonic acid monohydrate, and stir for 1 hour to obtain an acidified polyvinyl alcohol solution; A3. Add 6g of octaldehyde dropwise to an acidified polyvinyl alcohol solution and react for 2 hours to obtain reaction mixture A; A4. Pour reaction mixture A into 50 mL of saturated sodium bicarbonate solution and stir until the solution is completely precipitated. Dissolve the collected precipitate in dimethyl sulfoxide and pour the resulting solution into deionized water to collect the precipitate again. Soak and wash the precipitate in deionized water 3 times, each time for 1 day. Finally, freeze-dry to obtain modified polyvinyl alcohol.

[0029] Preparation Example 2

[0030] A modified polyvinyl alcohol is prepared according to the following method: A1. Place 5g of polyvinyl alcohol and 200mL of dimethyl sulfoxide in a round-bottom flask and heat at 90℃ to dissolve them, thus obtaining a polyvinyl alcohol solution. A2. Cool the obtained polyvinyl alcohol solution to 60°C, add 0.55g of p-toluenesulfonic acid monohydrate, and stir for 1 hour to obtain an acidified polyvinyl alcohol solution; A3. Add 7g of octaldehyde dropwise to an acidified polyvinyl alcohol solution and react for 2 hours to obtain reaction mixture A; A4. Pour reaction mixture A into 60 mL of saturated sodium bicarbonate solution and stir until the solution is completely precipitated. Dissolve the collected precipitate in dimethyl sulfoxide and pour the resulting solution into deionized water to collect the precipitate again. Soak the precipitate in deionized water three times, each time for one day, and finally freeze-dry to obtain modified polyvinyl alcohol.

[0031] Preparation Example 3

[0032] A zinc oxide containing oxygen vacancies is prepared according to the following method: Zn(OH)2 was treated in an air atmosphere at 400℃ for 3 hours to obtain ZnO. ZnO was then treated in a hydrogen atmosphere at 400℃ for 2 hours to obtain zinc oxide containing oxygen vacancies.

[0033] Preparation Example 4

[0034] A zinc oxide containing oxygen vacancies is prepared according to the following method: Zn(OH)2 was treated in an air atmosphere at 400℃ for 2 hours to obtain ZnO. ZnO was then treated in a hydrogen atmosphere at 400℃ for 1 hour to obtain zinc oxide containing oxygen vacancies.

[0035] Example 1

[0036] A radiation-cooling fabric is prepared according to the following method: S1. Add 5g of the modified polyvinyl alcohol obtained in Preparation Example 1 to 100mL of DMF, stir at 90℃ for 8h, and after stirring, add 1.5g of zinc oxide with oxygen vacancies obtained in Preparation Example 3, and disperse by ultrasonication to obtain a dispersion. S2. The dispersion was coated onto the surface of the cotton fabric and placed in saturated water vapor at room temperature for 36 hours. After the placement, the fabric was soaked and washed three times with deionized water for one day each time. Finally, the fabric was freeze-dried to obtain a radiation-cooling fabric with a radiation-cooling layer thickness of 150 μm.

[0037] Example 2

[0038] A radiation-cooling fabric is prepared according to the following method: S1. Add 5g of the modified polyvinyl alcohol obtained in Preparation Example 1 to 100mL of DMF, stir at 90℃ for 8h, and after stirring, add 1.0g of zinc oxide with oxygen vacancies obtained in Preparation Example 3, and disperse by ultrasonication to obtain a dispersion. S2. The dispersion was coated onto the surface of the cotton fabric and placed in saturated water vapor at room temperature for 36 hours. After the placement, the fabric was soaked and washed three times with deionized water for one day each time. Finally, the fabric was freeze-dried to obtain a radiation-cooling fabric with a radiation-cooling layer thickness of 150 μm.

[0039] Example 3

[0040] A radiation-cooling fabric is prepared according to the following method: S1. Add 5g of the modified polyvinyl alcohol obtained in Preparation Example 1 to 100mL of DMF, stir at 90℃ for 8h, and after stirring, add 2g of zinc oxide with oxygen vacancies obtained in Preparation Example 3, and disperse by ultrasonication to obtain a dispersion. S2. The dispersion was coated onto the surface of the cotton fabric and placed in saturated water vapor at room temperature for 36 hours. After the placement, the fabric was soaked and washed three times with deionized water for one day each time. Finally, the fabric was freeze-dried to obtain a radiation-cooling fabric with a radiation-cooling layer thickness of 150 μm.

[0041] Example 4

[0042] A radiation-cooling fabric is prepared according to the following method: S1. Add 5g of the modified polyvinyl alcohol obtained in Preparation Example 2 to 100mL of DMF, stir at 90℃ for 8h, and after stirring, add 1.5g of zinc oxide with oxygen vacancies obtained in Preparation Example 4, and disperse by ultrasonication to obtain a dispersion. S2. The dispersion was coated onto the surface of the cotton fabric and placed in saturated water vapor at room temperature for 36 hours. After the placement, the fabric was soaked and washed three times with deionized water for one day each time. Finally, the fabric was freeze-dried to obtain a radiation-cooling fabric with a radiation-cooling layer thickness of 150 μm.

[0043] Example 5

[0044] A radiation-cooling fabric is prepared according to the following method: S1. Add 5g of the modified polyvinyl alcohol obtained in Preparation Example 1 to 100mL of DMF, stir at 90℃ for 8h, and after stirring, add 1.5g of zinc oxide with oxygen vacancies obtained in Preparation Example 4, and disperse by ultrasonication to obtain a dispersion. S2. The dispersion was coated onto the surface of the cotton fabric and placed in saturated water vapor at room temperature for 36 hours. After the placement, the fabric was soaked and washed three times with deionized water for one day each time. Finally, the fabric was freeze-dried to obtain a radiation-cooling fabric with a radiation-cooling layer thickness of 150 μm.

[0045] Comparative Example 1

[0046] A radiation-cooling fabric is prepared according to the following method: S1. Add 5g of the modified polyvinyl alcohol obtained in Preparation Example 1 to 100mL of DMF, stir at 90℃ for 8h, and after stirring, add 0.5g of zinc oxide with oxygen vacancies obtained in Preparation Example 3, and disperse by ultrasonication to obtain a dispersion. S2. The dispersion was coated onto the surface of the cotton fabric and placed in saturated water vapor at room temperature for 36 hours. After the placement, the fabric was soaked and washed three times with deionized water for one day each time. Finally, the fabric was freeze-dried to obtain a radiation-cooling fabric with a radiation-cooling layer thickness of 150 μm.

[0047] Comparative Example 2

[0048] A radiation-cooling fabric is prepared according to the following method: S1. Add 5g of the modified polyvinyl alcohol obtained in Preparation Example 1 to 100mL of DMF, stir at 90℃ for 8h, and after stirring, add 2.5g of zinc oxide with oxygen vacancies obtained in Preparation Example 3, and disperse by ultrasonication to obtain a dispersion. S2. The dispersion was coated onto the surface of the cotton fabric and placed in saturated water vapor at room temperature for 36 hours. After the placement, the fabric was soaked and washed three times with deionized water for one day each time. Finally, the fabric was freeze-dried to obtain a radiation-cooling fabric with a radiation-cooling layer thickness of 150 μm.

[0049] Comparative Example 3

[0050] A radiation-cooling fabric was prepared according to the method of Example 1, except that "modified polyvinyl alcohol obtained in Preparation Example 1" in Example 1 was replaced with an equal weight of "polyvinyl alcohol".

[0051] Comparative Example 4

[0052] A radiation-cooling fabric was prepared according to the method of Example 1, except that "zinc oxide with oxygen vacancies obtained in Preparation Example 3" in Example 1 was replaced with an equal weight of "zinc oxide".

[0053] Comparative Example 5

[0054] A radiation-cooling fabric was prepared according to the method of Example 1, except that "modified polyvinyl alcohol obtained in Preparation Example 1" in Example 1 was replaced with an equal weight of "polyvinyl alcohol". Replace “zinc oxide with oxygen vacancies obtained in Preparation Example 3” with an equal weight of “zinc oxide”.

[0055] The performance of the radiation-cooling fabrics obtained in Examples 1-5 and Comparative Examples 1-5 was tested using the following methods: Reflectance: The reflectance of the sample in the range of 300-2500 nm was measured using a UV-Vis-NIR spectrometer (PerkinElmer Lambda 950, USA) with an integrating sphere.

[0056] Emissivity: Samples were analyzed from 660 to 4000 cm⁻¹ using a Fourier transform infrared spectrometer (FTIR, Nicolet 6700, USA) with a gold integrating sphere attachment (Peak). -1 Infrared emissivity test between them.

[0057] Abrasion resistance test: The radiation-cooled fabric was abraded with fine sandpaper. A sample was taken every 10 abrasions, and the change in reflectance of the radiation-cooled fabric after 200 abrasions was recorded. The change in reflectance (%) = reflectance of the un-abraded radiation-cooled fabric - reflectance of the radiation-cooled fabric after 200 abrasions. The results are shown in Table 1. Table 1

[0058] According to Table 1 and in conjunction with Examples 1-5, it can be seen that the reflectivity of the radiation-cooling fabric prepared by the present invention exceeds 91%, and the emissivity exceeds 89%. The reflectivity change of the radiation-cooling fabric after 200 rounds of sanding with fine sandpaper is less than 8% compared to the unsanded fabric, indicating that the radiation-cooling fabric prepared by the present invention has excellent radiation cooling performance and durability. In contrast, in Examples 1 and 1, due to the small amount of zinc oxide with oxygen vacancies, it cannot form a good synergistic effect with the modified polyvinyl alcohol, resulting in a smaller number of zinc oxide particles that can serve as "wear-resistant supports," leading to a decrease in the radiation cooling performance and durability of the radiation-cooling fabric. In Examples 1 and 2, due to the large amount of zinc oxide with oxygen vacancies, it is prone to agglomeration during the preparation of the dispersion, leading to a decrease in the radiation cooling performance and durability of the radiation-cooling fabric. In Examples 1 and 3, because the polyvinyl alcohol was not modified, its structure lacks the modification of medium- and long-chain alkane side chains. The cyclic acetal structure reduces the emissivity and hydrophobicity of the fabric, leading to a decrease in the radiative cooling performance and durability of the radiative cooling fabric. Combining Examples 1 and 4, the modified zinc oxide structure lacks oxygen vacancies, resulting in a narrow infrared response range and reduced reflectivity, further degrading the radiative cooling performance and durability of the fabric. Combining Examples 1 and 5, the lack of simultaneous modification of both polyvinyl alcohol and zinc oxide prevents the formation of a closed-loop "emission-reflection" system and the synergistic effect of the interface and structure, leading to a deterioration in the radiative cooling performance and durability of the cooling fabric. These results indicate that by rationally modifying polyvinyl alcohol, precisely controlling the oxygen vacancy structure of zinc oxide, and designing a suitable ratio between the two, a highly efficient synergistic system can be constructed, resulting in a radiative cooling fabric with excellent overall performance.

[0059] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0060] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A radiation-cooling fabric, characterized in that, It includes a substrate and a radiation cooling layer disposed on the substrate, wherein the raw materials of the radiation cooling layer include modified polyvinyl alcohol and zinc oxide containing oxygen vacancies; The modified polyvinyl alcohol is prepared by polyvinyl alcohol and medium- and long-chain saturated monohydric aldehyde under the catalysis of p-toluenesulfonic acid monohydrate, and the mass ratio of polyvinyl alcohol, medium- and long-chain saturated monohydric aldehyde and p-toluenesulfonic acid monohydrate is 1:(1-1.4):(0.07-0.11).

2. The radiation-cooling fabric according to claim 1, characterized in that, The substrate is any one or more of cellulose-based fabrics, polyester fabrics, and polypropylene fabrics.

3. The radiation-cooling fabric according to claim 1, characterized in that, The mass ratio of the modified polyvinyl alcohol to the oxygen-vacant zinc oxide is 1:(0.2-0.4).

4. The radiation-cooling fabric according to claim 1, characterized in that, The modified polyvinyl alcohol and zinc oxide with oxygen vacancies are independently distributed on the surface and inside the radiation cooling layer, respectively.

5. The radiation-cooling fabric according to claim 1, characterized in that, The medium- and long-chain saturated monohydric aldehydes are any one or more of the saturated monohydric aldehydes with 4-10 carbon atoms.

6. The radiation-cooling fabric according to claim 1, characterized in that, The method for preparing the modified polyvinyl alcohol includes the following steps: A1. Polyvinyl alcohol and dimethyl sulfoxide are placed in a glass container and heated to 90°C to dissolve them, thus obtaining a polyvinyl alcohol solution; A2. Cool the obtained polyvinyl alcohol solution to 60°C, add p-toluenesulfonic acid monohydrate, and stir for 1 hour to obtain an acidified polyvinyl alcohol solution; A3. Add medium- to long-chain saturated monohydric aldehydes dropwise to an acidified polyvinyl alcohol solution and react for 1-3 hours to obtain reaction mixture A; A4. Pour reaction mixture A into a saturated sodium bicarbonate solution, stir, and allow precipitation. Wash and dry the precipitate to obtain modified polyvinyl alcohol.

7. The radiation-cooling fabric according to claim 6, characterized in that, The ratio of polyvinyl alcohol to dimethyl sulfoxide is 1 g:(30-50) mL.

8. The radiation-cooling fabric according to claim 1, characterized in that, The zinc oxide containing oxygen vacancies was obtained by heat treatment of Zn(OH)2 in air at 400°C and hydrogen at 400°C, respectively.

9. A method for preparing a radiation-cooled fabric, characterized in that, The preparation of the radiation-cooling fabric according to any one of claims 1-8 includes the following steps: S1. Add modified polyvinyl alcohol to N,N-dimethylformamide and stir at 90°C for 6-10 hours. After stirring, add zinc oxide containing oxygen vacancies and disperse by ultrasonication to obtain a dispersion. S2. Coat the dispersion onto the substrate surface and place it in saturated water vapor at room temperature for 24-48 hours. After the placement is completed, wash and soak it with deionized water, and then dry it to obtain the radiation cooling fabric.

10. The method for preparing the radiation-cooled fabric according to claim 9, characterized in that, The ratio of modified polyvinyl alcohol to DMF is (14-16) g: 100 mL.

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