Cross-linked network structure radiation refrigeration film and preparation method and application thereof

Abstract

The invention discloses a cross-linked network structure radiation refrigeration film and a preparation method and application thereof, and belongs to the technical field of radiation refrigeration materials. Bacterial cellulose and water-based acrylic acid are mixed to obtain a bacterial cellulose solution in an adhesive state; the preparation method comprises the following steps: mixing TiO2 with deionized water, and carrying out ultrasonic treatment to obtain a uniformly dispersed TiO2 solution; pouring the TiO2 solution into the bacterial cellulose solution to obtain a white solution; pouring into a culture dish and drying to obtain a porous bacterial cellulose composite membrane with a cross-linked network structure; polydimethylsiloxane is fused into cyclohexane, the mixture is sprayed to one side of the porous bacterial cellulose composite film through a spray gun, then heat treatment is carried out, and the radiation refrigeration film of the cross-linked network structure with one hydrophilic side and the other hydrophobic side is obtained and has the high solar reflectivity, daytime cooling is facilitated, surface hydrophobization treatment of polydimethylsiloxane is achieved, and the radiation refrigeration effect is good. And dust and complex weather in the daily use process can be dealt with, so that long-time radiation refrigeration can be maintained.

Description

Technical Field

[0001] The invention belongs to the technical field of radiation refrigeration materials, and in particular relates to a cross-linked network structure radiation refrigeration film and a preparation method and application thereof. Background Art

[0002] The acceleration of global industrialization and population growth have led to an increase in energy consumption. Achieving carbon neutrality is the primary global environmental goal to alleviate the energy crisis. Residential buildings account for 40% of global energy consumption each year, a large part of which is consumed by building cooling and air-conditioning systems. Therefore, it is imperative to improve the efficiency of existing cooling systems and develop new refrigeration technologies to improve building energy efficiency.

[0003] As a green cooling strategy, radiative cooling can achieve passive cooling without external energy support. Specifically, it refers to a specially designed radiative cooling device that can effectively block the heat input from the sun while emitting infrared radiation to the universe in the atmospheric window band range (8μm-13μm) by virtue of its optimized material surface structure and radiation characteristics, thereby achieving the purpose of lowering its own temperature. Given the significant temperature difference between the low temperature environment of outer space (about 3K) and the relatively high ambient temperature of the earth's surface (about 300K), this natural temperature difference enables the exchange of heat radiation from earth objects to the universe to be cleverly utilized to achieve a cooling effect. Similar to the technical methods of utilizing other natural energy sources such as geothermal energy, radiative cooling can be used as an innovative energy-saving technology with the help of natural cold sources in the universe. It can not only play a key role in the temperature control system of buildings and reduce the energy consumption of air-conditioning systems, but also be applied to many fields such as heat dissipation of temperature-sensitive electronic chips, battery thermal management of new energy vehicles, and temperature control assurance of aerospace equipment. It has extremely considerable application potential and development space, and is expected to play an important role in the global energy conservation, emission reduction and sustainable development process.

[0004] The rich functional groups in the polymer can vibrate within a specific wavelength range, thereby emitting infrared radiation that matches the atmospheric window band, releasing the heat of the object into the universe in the form of infrared radiation, and achieving the purpose of cooling. However, pure polymer-based radiation cooling materials have low solar reflectivity. To solve this problem, it has been proposed to solve the defects of polymer-based materials by doping with inorganic nanoparticles or porous structures. Despite this, the pain points faced, such as UV resistance, poor mechanical properties, and difficulty in degradation, still need to be solved.

[0005] Therefore, finding a more suitable production method to solve the above-mentioned problems of existing polymer-based radiation cooling materials has become one of the focuses of widespread attention of many forward-looking researchers in the field. Summary of the invention

[0006] Technical problem to be solved: This application mainly proposes a cross-linked network structure radiation refrigeration film and its preparation method and application, to solve the technical problems of low solar reflectivity, UV resistance, poor mechanical properties, and difficult degradation of simple polymer-based radiation refrigeration materials in the prior art. The cross-linked network structure radiation refrigeration film provided by the application uses bacterial cellulose as a base and is compounded with functional nanomaterials to realize the cross-linked network structure and porous structure design process of the radiation refrigeration material; it is a refrigeration material with high reflectivity and high emissivity, long-term durability and good UV resistance; and the preparation method is simple, controllable, and suitable for large-scale production and application.

[0007] Technical solution:

[0008] A method for preparing a cross-linked network structure radiant refrigeration film, the method for preparing the cross-linked network structure radiant refrigeration film specifically comprising the following steps:

[0009] Step 1: Mix 5-40 parts of bacterial cellulose and 0.01-1 part of aqueous acrylic acid according to the mass ratio and stir at 400 r / min at room temperature for 1 hour to obtain a bacterial cellulose solution in a sticky state;

[0010] Step 2: Mix 0.01-2.5 parts of TiO2 with 5-80 parts of deionized water according to the mass ratio, and ultrasonicate at 80kHZ for 1h to obtain a uniformly dispersed TiO2 solution;

[0011] The third step is to pour the uniformly dispersed TiO2 solution into the sticky bacterial cellulose solution and stir at 400 r / min for 2 h to obtain a uniform white solution;

[0012] The fourth step is to pour the white solution into a culture dish, put it into an oven and perform drying heat treatment at 30°C to 60°C to obtain a porous bacterial cellulose composite membrane with a cross-linked network structure;

[0013] Step 5: Dissolve 0.5-2 parts of polydimethylsiloxane into 2.5-8 parts of cyclohexane according to the mass ratio, spray 0.1 mL per square centimeter on one side of the porous bacterial cellulose composite membrane, and then dry and heat treat to obtain a porous bacterial cellulose composite membrane with one side being hydrophilic and the other side being hydrophobic, i.e., a cross-linked network structure radiation refrigeration film.

[0014] As a preferred technical solution of the present invention: the mass fraction of the aqueous acrylic acid in the first step is 0.5%.

[0015] As a preferred technical solution of the present invention: the mass ratio of TiO2 to deionized water in the second step is 1:20 to 1:80.

[0016] As a preferred technical solution of the present invention: the particle size of TiO2 in the second step is 100nm.

[0017] As a preferred technical solution of the present invention: the heat treatment temperature in the fourth step is between 35°C and 50°C.

[0018] As a preferred technical solution of the present invention: the fifth step heat treatment temperature is 80°C; the heat treatment time is 120 minutes.

[0019] As a preferred technical solution of the present invention: the mass ratio of polydimethylsiloxane to cyclohexane in the fifth step is 1:2 to 1:10.

[0020] The present application also discloses a cross-linked network structure radiation refrigeration film obtained by any of the above-mentioned preparation methods. The cross-linked network structure radiation refrigeration film is a composite material of bacterial cellulose and TiO2. The staggered arrangement of fibers in the bacterial cellulose forms a three-dimensional network structure with high stability. The cross-linked network structure radiation refrigeration film has a highly permeable channel with a pore size of 100-400nm.

[0021] As a preferred technical solution of the present invention: the color of the cross-linked network structure radiation refrigeration film is white.

[0022] A cross-linked network structure radiation cooling film is used in building energy conservation, photovoltaic systems and food packaging.

[0023] Principle explanation: The cross-linked network structure radiation refrigeration film provided by the present invention is a composite material of bacterial cellulose and TiO2. Due to the absorption vibration of the COC and C-OH characteristic molecular bonds in the bacterial cellulose molecules, the bacterial cellulose shows significant infrared radiation in the atmospheric transparency window; in addition, the fiber structure of bacterial cellulose is similar to the wavelength of sunlight, and the 100-400nm pore structure formed during the drying process helps to improve the solar reflectivity.

[0024] Beneficial effects: The preparation method of the cross-linked network structure radiant refrigeration film described in the present application adopts the above technical solution and has the following technical effects compared with the prior art:

[0025] 1. The cross-linked network structure radiation refrigeration film provided by the present invention has a network structure with staggered fibers and a large number of air permeable channels formed by porous structures. Different from other radiation refrigeration materials, the cross-linked network structure radiation refrigeration film prepared by the present invention provides a good carrier for the dispersion of TiO2 due to the unique three-dimensional network structure of bacterial cellulose, thereby maximizing the anti-ultraviolet performance of titanium dioxide to obtain excellent anti-aging ability and long-term durability;

[0026] 2. The cross-linked network structure radiation refrigeration film provided by the present invention has a pore structure of 100-400nm, which effectively enhances the scattering of sunlight. The cross-linked network structure radiation refrigeration film benefits from the three-dimensional network structure of bacterial cellulose and effectively solves the problems of easy aging and poor mechanical properties of existing radiation refrigeration materials;

[0027] 3. The present invention designs a simple spraying method to prepare a hydrophobic cross-linked network structure radiation cooling film, prepares a mixed solution of polydimethylsiloxane and cyclohexane, sprays the mixed solution on one side of the bacterial cellulose composite mold through a spray gun, and dries it in an oven at 80°C for 120 minutes to obtain a porous bacterial cellulose composite film with one side hydrophilic and one side hydrophobic. The porous bacterial cellulose composite film with a cross-linked network structure is synthesized by stirring and spraying. The staggered arrangement of fibers forms a three-dimensional network structure with a pore size of 100-400nm, which has a high solar reflectivity and is conducive to daytime cooling. The surface hydrophobic treatment of polydimethylsiloxane is conducive to dealing with dust and complex weather during daily use to maintain long-term radiation cooling;

[0028] 4. The preparation method provided by the present invention is simple, economical, and has good controllability, is suitable for large-scale production and application, and has broad application prospects in the fields of building energy conservation, photovoltaic systems, food packaging, etc.;

[0029] 5. The cross-linked network structure radiation refrigeration film provided by the present invention has long-term stable anti-aging ability and high-performance refrigeration effect for daytime and nighttime cooling. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the structure of the cross-linked network structure radiation cooling film of this application;

[0031] Figure 2 A physical picture of the cross-linked network structure radiation cooling film sample prepared for this application;

[0032] Figure 3 The scanning electron microscope images of the cross-linked network structure radiation cooling film prepared in this application, wherein the left image is the top surface image of the film sprayed with polydimethylsiloxane, the middle image is the bottom surface image without the spray of polydimethylsiloxane, and the right image is the bottom surface image without the spray of polydimethylsiloxane;

[0033] Figure 4 The spectral emissivity diagram of the cross-linked network structure radiation cooling film prepared in this application at 0.3-20 μm;

[0034] Figure 5 Schematic diagram of a homemade device for outdoor testing of cooling performance of the cross-linked network structure radiant cooling film prepared in this application;

[0035] Figure 6The refrigeration performance diagram of the cross-linked network structure radiant refrigeration film prepared in this application during the day and at night, wherein the left figure is the refrigeration performance diagram during the day, and the right figure is the refrigeration performance diagram at night;

[0036] Figure 7 A schematic diagram of a device for UV resistance testing of a cross-linked network structure radiation cooling film prepared in this application;

[0037] Figure 8 This is a spectral emissivity diagram of the cross-linked network structure radiation cooling film prepared in this application at 0.3-20μm after ultraviolet irradiation. DETAILED DESCRIPTION

[0038] In order to further illustrate the present invention, the preferred implementation scheme provided by the present invention is described below in conjunction with examples. However, it should be understood that these examples are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating processes are given only to further illustrate the characteristics and advantages of the present invention, rather than to limit the claims of the present invention. The protection scope of the present invention is not limited to the following examples.

[0039] All raw materials of the present invention have no particular limitation on their sources, and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0040] There is no particular restriction on the purity of all raw materials in the present invention. The present invention preferably uses analytically pure materials or materials with purities commonly used in the field of photothermal interface materials. In the present application, bacterial cellulose was purchased from Shansi Technology.

[0041] Example 1

[0042] A method for preparing a cross-linked network structure radiation refrigeration film, the specific method comprising the following steps:

[0043] Step 1: 10 parts of bacterial cellulose and 0.06 parts of aqueous acrylic acid were mixed and stirred at 400 r / min at room temperature for 1 hour to obtain a bacterial cellulose solution in a sticky state;

[0044] Step 2: Mix 2 parts of TiO2 with 60 parts of deionized water according to the mass ratio, and ultrasonicate at 80kHZ for 1 hour to obtain a uniformly dispersed TiO2 solution; the mass ratio of TiO2 to deionized water is 1:30, and the particle size of TiO2 is 100nm;

[0045] The third step is to pour the uniformly dispersed TiO2 solution into the sticky bacterial cellulose solution and stir at 400 r / min for 2 h to obtain a uniform white solution;

[0046] Step 4: pour the white solution into a culture dish, put it into an oven and perform drying heat treatment at 30°C to 60°C to obtain a porous bacterial cellulose composite membrane with a cross-linked network structure;

[0047] Step 5: Dissolve 1 part of polydimethylsiloxane in 4 parts of cyclohexane according to the mass ratio, spray 0.1 mL per square centimeter on one side of the porous bacterial cellulose composite membrane, and then dry it in an oven at 80°C for 120 minutes to obtain a porous bacterial cellulose composite membrane with one side hydrophilic and the other side hydrophobic, that is, a cross-linked network structure radiation refrigeration film.

[0048] See also Figure 1 , Figure 1 This is a schematic diagram of the structure of a porous bacterial cellulose composite membrane with a cross-linked network structure prepared in the present invention.

[0049] Example 2

[0050] A method for preparing a cross-linked network structure radiation refrigeration film, the specific method comprising the following steps:

[0051] Step 1: 15 parts of bacterial cellulose and 0.08 parts of aqueous acrylic acid were mixed and stirred at 400 r / min at room temperature for 1 hour to obtain a bacterial cellulose solution in a sticky state;

[0052] Step 2: Mix 1 part of TiO2 with 50 parts of deionized water according to the mass ratio, and ultrasonicate at 80kHZ for 1h to obtain a uniformly dispersed TiO2 solution; the mass ratio of TiO2 to deionized water is 1:50, and the particle size of TiO2 is 100nm;

[0053] The third step is to pour the uniformly dispersed TiO2 solution into the sticky bacterial cellulose solution and stir at 400 r / min for 2 h to obtain a uniform white solution;

[0054] Step 4: pour the white solution into a culture dish, put it into an oven and perform drying and heat treatment at 35°C to 50°C to obtain a porous bacterial cellulose composite membrane with a cross-linked network structure;

[0055] Step 5: Dissolve 1 part of polydimethylsiloxane in 4 parts of cyclohexane according to the mass ratio, spray 0.1 mL per square centimeter on one side of the porous bacterial cellulose composite membrane, and then dry it in an oven at 80°C for 120 minutes to obtain a porous bacterial cellulose composite membrane with one side hydrophilic and the other side hydrophobic, that is, a cross-linked network structure radiation refrigeration film.

[0056] Example 3

[0057] A method for preparing a cross-linked network structure radiant cooling film is provided. The cross-linked network structure radiant cooling film is prepared by a template-free method. The specific method comprises the following steps:

[0058] Step 1: Mix 30 parts of bacterial cellulose BC and 0.15 parts of aqueous acrylic acid AA according to the mass ratio and stir at 400 r / min at room temperature for 1 hour to obtain a bacterial cellulose solution in a viscous state, which is recorded as ABC;

[0059] Step 2: Mix 0.5 parts of TiO2 with 30 parts of deionized water according to the mass ratio, and ultrasonicate at 80kHZ for 1 hour to obtain a uniformly dispersed TiO2 solution; the mass ratio of TiO2 to deionized water is 1:60, and the particle size of TiO2 is 100nm;

[0060] The third step is to pour the uniformly dispersed TiO2 solution into the sticky bacterial cellulose solution and stir at 400 r / min for 2 h to obtain a uniform white solution;

[0061] The fourth step is to pour the white solution into a culture dish and put it into an oven for drying and heat treatment at 40°C to 45°C to dehydrate the mixed solution of bacterial cellulose, aqueous acrylic acid and TiO2 to form a film, thereby obtaining a porous bacterial cellulose composite membrane ABCT with a three-dimensional network structure;

[0062] Step 5: Dissolve 1 part of polydimethylsiloxane in 4 parts of cyclohexane according to the mass ratio, spray 0.1 mL per square centimeter on one side of the porous bacterial cellulose composite membrane ABCT, and then dry it in an oven at 80°C for 120 minutes to solidify the polydimethylsiloxane to obtain a porous bacterial cellulose composite membrane PABCT with a hydrophilic side and a hydrophobic side, i.e. a cross-linked network structure radiation refrigeration film.

[0063] Specifically, the composite film has a pore structure of 100-400 nm, and has the performance of enhancing solar scattering and improving air permeability.

[0064] The invention simply mixes and stirs commercial bacterial cellulose and aqueous acrylic acid, injects a TiO2 solution with good ultrasonic dispersion, performs heat treatment to dehydrate and form a film, and then sprays a layer of a mixed solution of polydimethylsiloxane and cyclohexane to obtain a hydrophobic porous bacterial cellulose composite film after heat treatment.

[0065] The present invention also provides the use of the porous bacterial cellulose composite film described in any one of the above technical solutions or the porous bacterial cellulose composite film prepared by the preparation method described in any one of the above technical solutions in building energy conservation, photovoltaic systems, and food packaging.

[0066] The cross-linked network structure radiation cooling film provided by the present invention has a network structure with staggered fiber arrangement and a large number of air permeable channels formed by porous structures. Due to the unique three-dimensional network structure of bacterial cellulose, a good carrier is provided for the dispersion of TiO2, thereby maximizing the anti-ultraviolet performance of titanium dioxide to obtain superior anti-aging ability and long-term durability; on the other hand, the composite film has a 100-400nm pore structure, which effectively enhances the scattering of sunlight. The porous bacterial cellulose composite film with a cross-linked network structure provided by the present invention benefits from the three-dimensional network structure of bacterial cellulose and effectively solves the problems of easy aging and poor mechanical properties of existing radiation cooling materials.

[0067] Example 4

[0068] A method for preparing a cross-linked network structure radiant cooling film is provided. The cross-linked network structure radiant cooling film is prepared by a template-free method. The specific method comprises the following steps:

[0069] Step 1: 20 mL of bacterial cellulose BC and 0.1 mL of aqueous acrylic acid AA were mixed and stirred at 400 r / min for 1 h at room temperature to obtain a viscous bacterial cellulose solution, which was recorded as ABC.

[0070] Step 2: Mix 0.2 parts of TiO2 with 10 parts of deionized water according to the mass ratio, and ultrasonicate at 80kHZ for 1h to obtain a uniformly dispersed TiO2 solution; the TiO2 particle size is 100nm;

[0071] The third step is to pour the uniformly dispersed TiO2 solution into the sticky bacterial cellulose solution and stir at 400 r / min for 2 h to obtain a uniform white solution;

[0072] The fourth step is to pour the white solution into a culture dish and put it into an oven for drying and heat treatment at 40°C to 45°C to dehydrate the mixed solution of bacterial cellulose, aqueous acrylic acid and TiO2 to form a film, thereby obtaining a porous bacterial cellulose composite membrane ABCT with a three-dimensional network structure;

[0073] Step 5: Dissolve 1 part of polydimethylsiloxane in 4 parts of cyclohexane according to the mass ratio, spray 0.1 mL per square centimeter on one side of the porous bacterial cellulose composite membrane ABCT, and then dry it in an oven at 80°C for 120 minutes to solidify the polydimethylsiloxane to obtain a porous bacterial cellulose composite membrane PABCT with a hydrophilic side and a hydrophobic side, i.e. a cross-linked network structure radiation refrigeration film.

[0074] See also Figure 2 , Figure 2This is a physical picture of the cross-linked network structure radiation cooling film sample prepared in this application; among them, from left to right are the porous bacterial cellulose composite membrane (PABCT) sprayed with polydimethylsiloxane and the porous bacterial cellulose composite membrane (ABCT) not sprayed with polydimethylsiloxane.

[0075] See also Figure 3 , Figure 3 These are scanning electron microscope images of the cross-linked network structure radiation refrigeration film prepared in this application, wherein the left image is a picture of a porous bacterial cellulose composite membrane (PABCT) sprayed with polydimethylsiloxane, the middle image is a picture of a porous bacterial cellulose composite membrane (ABCT) not sprayed with polydimethylsiloxane, and the right image is a picture of a porous bacterial cellulose composite membrane (ABCT) not sprayed with polydimethylsiloxane.

[0076] See also Figure 4 , Figure 4 The spectral emissivity diagram of the cross-linked network structure radiation cooling film prepared in this application at 0.3-20 μm;

[0077] See also Figure 5 , Figure 5 Schematic diagram of a homemade device for outdoor testing of cooling performance of the cross-linked network structure radiant cooling film prepared in this application;

[0078] For further explanation, the refrigeration performance of the prepared cross-linked network structure radiation refrigeration film was characterized.

[0079] See also Figure 6 , Figure 6 The refrigeration performance diagram of the cross-linked network structure radiant refrigeration film prepared in this application during the day and at night, wherein the left figure is the refrigeration performance diagram during the day, and the right figure is the refrigeration performance diagram at night;

[0080] See also Figure 7 , Figure 7 A schematic diagram of a device for UV resistance testing of a cross-linked network structure radiation cooling film prepared in this application;

[0081] See also Figure 8 , Figure 8 This is a spectral emissivity diagram of the cross-linked network structure radiation cooling film prepared in this application at 0.3-20μm after ultraviolet irradiation.

[0082] The results show that PABCT benefits from its network structure with staggered fibers and a large number of porous structures. PABCT exhibits low absorptivity in the solar band and high emissivity in the atmospheric window band. As a radiation cooler, PABCT has a solar absorptivity of 10.9% and an atmospheric window emissivity of 94.6%. In the outdoor cooling performance test, the maximum temperature drop relative to the ambient temperature during the day was 7.15°C, and the average temperature drop was 4.85°C; the maximum temperature drop relative to the ambient temperature during the day was 2.7°C, and the average temperature drop was 2.32°C. It also has excellent anti-ultraviolet performance. The present invention has opened up a new way to further develop radiation refrigeration materials with anti-aging and high refrigeration efficiency.

[0083] The above is a detailed introduction to the preparation method and application of a porous bacterial cellulose composite membrane with a cross-linked network structure provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and core ideas of the present invention, including the best mode, and also enables any technician in the field to practice the present invention, including the manufacture and use of any device or system, and the implementation of any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements that are not different from the text of the claims, or if they include equivalent structural elements that are not substantially different from the text of the claims, then these other embodiments should also be included in the scope of the claims.

[0084] The embodiments of the present invention are described in detail above, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A method for preparing a cross-linked network structure radiation refrigeration film, characterized in that: The preparation method specifically comprises the following steps: Step 1: Mix 5-40 parts of bacterial cellulose and 0.01-1 part of aqueous acrylic acid according to the mass ratio and stir at 400 r / min at room temperature for 1 hour to obtain a bacterial cellulose solution in a sticky state; Step 2: Mix 0.01-2.5 parts of TiO2 with 5-80 parts of deionized water according to the mass ratio, and ultrasonicate at 80kHZ for 1h to obtain a uniformly dispersed TiO2 solution; The third step is to pour the uniformly dispersed TiO2 solution into the sticky bacterial cellulose solution and stir at 400 r / min for 2 h to obtain a uniform white solution; The fourth step is to pour the white solution into a culture dish, put it into an oven and perform drying heat treatment at 30°C to 60°C to obtain a porous bacterial cellulose composite membrane with a cross-linked network structure; Step 5: Dissolve 0.5-2 parts of polydimethylsiloxane into 2.5-8 parts of cyclohexane according to the mass ratio, spray 0.1 mL per square centimeter on one side of the porous bacterial cellulose composite membrane, and then dry and heat treat to obtain a porous bacterial cellulose composite membrane with one side being hydrophilic and the other side being hydrophobic, i.e., a cross-linked network structure radiation refrigeration film.

2. The method for preparing the cross-linked network structure radiant cooling film according to claim 1, characterized in that: The mass fraction of the aqueous acrylic acid in the first step is 0.5%.

3. The method for preparing the cross-linked network structure radiation cooling film according to claim 1, characterized in that: The mass ratio of TiO2 to deionized water in the second step is 1:20 to 1:

80.

4. The method for preparing a cross-linked network structure radiant cooling film according to claim 1, characterized in that: The particle size of TiO2 in the second step is 100nm.

5. The method for preparing a cross-linked network structure radiant cooling film according to claim 1, characterized in that: The heat treatment temperature in the fourth step is between 35°C and 50°C.

6. The method for preparing a cross-linked network structure radiant cooling film according to claim 1, characterized in that: The fifth step heat treatment temperature is 80° C. and the heat treatment time is 120 min.

7. The method for preparing a cross-linked network structure radiant cooling film according to claim 1, characterized in that: The mass ratio of polydimethylsiloxane to cyclohexane in the fifth step is 1:2 to 1:

10.

8. A cross-linked network structure radiation cooling film prepared by the preparation method according to any one of claims 1 to 7, characterized in that: The cross-linked network structure radiation cooling film is a composite material of bacterial cellulose and TiO2. The staggered arrangement of the fibers in the bacterial cellulose forms a three-dimensional network structure with high stability. The cross-linked network structure radiation cooling film has a highly permeable channel with a pore size of 100-400nm.

9. The cross-linked network structure radiant cooling film according to claim 8, characterized in that: The color of the cross-linked network structure radiation refrigeration film is white.

10. Use of the cross-linked network structure radiation cooling film according to claim 8 in building energy conservation, photovoltaic systems, and food packaging.

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