Multifunctional super fabric for radiative cooling and method of making the same

Abstract

This invention discloses a multifunctional metafabric for radiative cooling and its preparation method. The fabric comprises a fabric layer, an adhesive layer, and an aerogel layer. The fabric layer and the aerogel layer are composited by the adhesive layer. The aerogel layer is a titanium dioxide aerogel with a three-dimensional tubular structure and a sheet-like electrospun fiber membrane containing magnetic core-shell particles loaded on the skeleton. The multifunctional metafabric for radiative cooling has high solar reflectivity (0.90-0.98) and high infrared emissivity (0.90-0.97), and can achieve a surface temperature lower than the substrate and ambient temperature under direct midday sunlight. It has excellent outdoor radiative cooling, flame retardant, and antibacterial capabilities.

Description

Technical Field

[0001] This invention relates to a multifunctional superfabric for radiation cooling and its preparation method, belonging to the field of functional materials technology. Background Technology

[0002] Passive daytime radiative cooling (PDRC) is completely environmentally friendly, requiring no additional energy consumption. It emits its energy into ultra-cool outer space (3K) by reflecting sunlight (0.3-2.5 μm) and simultaneously through a first atmospheric transparent window (8-13 μm). This holds great promise for preventing the misuse of traditional compressed air-based refrigeration systems. In recent years, daytime radiative cooling has been demonstrated and developed, attracting the interest of researchers in the field. In principle, one of the key solutions for achieving passive sub-environmental daytime radiative cooling is to reduce the negative impact of solar radiation on the radiative cooler, as the power of solar radiation is far greater than the cooling capacity. Furthermore, the high temperatures of summer pose a serious challenge to human health, particularly causing heat-induced diseases and related complications such as heat paralysis, skin cancer, and cardiovascular diseases. Therefore, the exploration of personal cooling technology has recently been a focus of significant effort. Personal thermoregulation, by providing cooling or heating to the body, creates a microclimate of thermal comfort, meeting the demand for innovative textiles that can aid in human thermoregulation. Summary of the Invention

[0003] Technical problem to be solved: The purpose of this invention is to provide a multifunctional superfabric for radiative cooling and its preparation method, which uses scraping printing and interlayer composite technology to endow the fabric with outdoor radiative cooling capability.

[0004] Technical solution:

[0005] A multifunctional superfabric for radiative cooling, characterized in that: the fabric comprises a fabric layer, an adhesive layer and an aerogel layer, the fabric layer and the aerogel layer are composited by the adhesive layer, and the aerogel layer is a titanium dioxide aerogel with a three-dimensional tubular structure and a sheet-like electrospun fiber membrane containing magnetic core-shell particles loaded on the skeleton.

[0006] The method for preparing the multifunctional superfabric for radiation cooling includes the following steps:

[0007] S1. Take polytetrafluoroethylene emulsion, binder and thickener in a mass ratio of 10~30:15~25:1.5~3, stir evenly to obtain color paste;

[0008] S2. After uniformly printing the color paste onto the pretreated fabric, titanium dioxide aerogel is loaded onto the fabric surface to obtain printed superfabric. After pre-baking, it is baked to obtain a multifunctional superfabric for radiation cooling.

[0009] The preparation method of the titanium dioxide aerogel in S2 includes the following steps:

[0010] S1-1. Tetrabutyl titanate and glacial acetic acid are mixed and then added to anhydrous ethanol and stirred to obtain homogeneous solution A;

[0011] S1-2. Take water with a volume ratio of 1~3:2~4 and anhydrous ethanol and mix them evenly. Then add concentrated hydrochloric acid to adjust the pH to 1~3 and stir evenly to obtain solution B.

[0012] S1-3. Slowly add solution B to homogeneous solution A, then add sheet-like electrospun fiber membrane, and stir magnetically for 1-3 hours to obtain gel;

[0013] S1-4. Place the gel obtained in S1-3 in a magnetic field for 100~500 min, and then remove the device to obtain a gel oriented along the direction of the sheet-like statically spun fiber membrane;

[0014] S1-5. Orient the gel obtained in S1-4 at -40~-20℃ and freeze-dry for 12~20h to obtain titanium dioxide aerogel;

[0015] The method for preparing the sheet-like electrospun fiber membrane in S1-3 includes the following steps:

[0016] S2-1. Take tetrabutyl titanate and glacial acetic acid in a molar ratio of 1~2.5:1~2.8 and stir magnetically at 40~60℃ to obtain a homogeneous solution;

[0017] S2-2. Add magnetic core-shell particles to the solution obtained in S2-1 and disperse them ultrasonically to obtain an electrospinning solution with a mass fraction of 5~20wt%;

[0018] S2-3. Electrospinning is performed using the electrospinning solution obtained in S2-2 at a voltage of 15~20kV and a flow rate of 1~1.5mL / h to obtain an electrospun fiber membrane;

[0019] S2-4. The electrospun fiber membrane obtained in S2-3 is pulverized to obtain a size of 1~2 mm. 2 Sheet-shaped electrospun fiber membrane.

[0020] Preferably, the pretreated fabric is one of commercial cotton, polyester, nylon, linen, silk or spandex fabric, the pre-drying time is 5~10 min, the pre-drying temperature is 60~80℃, the baking time is 5~10 min, and the baking temperature is 120~150℃.

[0021] Preferably, the mass of tetrabutyl titanate in S1-1 is 55-70% of that in solution A, and the volume ratio of glacial acetic acid to anhydrous ethanol is 1-3:5-15.

[0022] Preferably, the method for preparing the magnetic core-shell particles in S2-2 includes the following steps:

[0023] S3-1. Take terephthalic acid and zinc acetate dihydrate in a mass ratio of 0.2~0.6:1 and add them to a solution of triethylamine, DMF and ethanol in a volume ratio of 1~3:3~15:14~20 to obtain a mixed solution;

[0024] S3-2. Add the Fe3O4 suspension and inorganic particle suspension with a volume ratio of 1~3:2~5 to the mixed solution obtained in S3-1, and stir magnetically for 3 hours;

[0025] S3-3. After centrifuging and washing the product obtained in S3-2, Fe3O4@MOF-5@inorganic particles were obtained. The particles were then dispersed in water to obtain suspension A.

[0026] S3-4. Mix water at a volume ratio of 20:1 with titanium trichloride precursor until homogeneous, then add sodium bicarbonate solution with a concentration of 1~3 mol / L to adjust the pH to 2~5 to obtain solution B;

[0027] S3-5. Add the suspension A obtained in S3-3 to the solution B obtained in S3-4 and react for 10-50 min. After centrifugation, washing and drying, magnetic core-shell particles are obtained.

[0028] Preferably, the concentration ratio of Fe3O4 suspension to inorganic particle suspension in S3-2 is 1~4:1~9, and the inorganic particle suspension is one or more of BaSO4 suspension, CaCO3 suspension, Al2O3 suspension, TiO2 suspension, ZnO2 suspension, AlPO4 suspension, hollow glass microsphere suspension or SiC suspension.

[0029] Preferably, the ratio of Fe3O4@MOF-5@inorganic particles in suspension A to ferric chloride precursor in solution B in S3-5 is 1:15 to 1:70.

[0030] Beneficial effects: The multifunctional superfabric for radiation cooling prepared in this invention has the following advantages:

[0031] 1. The presence of the core-shell structure interface and structural differences in the magnetic core-shell particles prepared by this invention effectively expands the scattering cross section, promotes strong scattering of incident light, and thus improves solar reflectivity. In addition, the presence of Fe3O4, inorganic particles and MOF-5 in the magnetic core-shell particles increases the surface area of ​​the material, further improving the scattering efficiency of sunlight and infrared emissivity, thereby enhancing the radiative cooling performance.

[0032] 2. The tubular structure prepared by controlling the directional arrangement of the sheet-like electrospun fiber membrane in this invention can be regarded as a tubular grating, which improves and expands the solar reflectivity. In addition, the presence of the sheet-like electrospun fiber membrane can enhance the mechanical stability of the aerogel while forming a porous structure, improve its adaptability to substrate deformation, and meet the actual use requirements.

[0033] 3. The titanium dioxide aerogel prepared in this invention has high porosity and large specific surface area, thereby improving the ability to scatter the solar spectrum. In addition, it has high infrared emissivity in the atmospheric window band, which helps to effectively emit heat and thus improve the radiative cooling performance.

[0034] 4. The coating prepared by the present invention has micropores formed by the volatilization of polytetrafluoroethylene during baking. According to the Mie scattering principle, the coating has a strong ability to backscatter sunlight and enhance thermal radiation due to the presence of micro-nano pore structure.

[0035] 5. The multifunctional superfabric coating for radiative cooling designed in this invention is suitable for personal thermal management and energy-saving building coatings. It has high solar reflectivity (0.90-0.97) and high infrared emissivity (0.94-0.98), and the outdoor cooling effect can reach 7.2℃. It not only has excellent outdoor cooling capacity, but also has a low thermal conductivity and resistance to environmental aging.

[0036] 6. This invention designs a multifunctional microfabric for radiative cooling that can withstand long-term ultraviolet radiation without changing color, has good physical and chemical stability, strong durability, and long service life, and achieves long-term stable cooling performance. In addition, the microfabric coating is endowed with multiple functions such as waterproof (contact angle of 141.6°), flame retardant (LOI of 30.1%), and antibacterial (bacteriostatic rate of 98.2%). Attached Figure Description

[0037] Figure 1 For indoor cooling evaluation: (a) Diagram of self-made cooling evaluation device, (b) indoor xenon lamp simulation of temperature change of a sample under one sun;

[0038] Figure 2 Temperature change curves of outdoor human clothing made of cotton and the sample from Example 1 under sunlight exposure;

[0039] Figure 3 Environmental conditions for the day of outdoor testing: (a) wind speed and relative humidity, (b) solar radiation power. Detailed Implementation

[0040] The present invention will be further described below with reference to embodiments. These embodiments are illustrative of the present invention, but the present invention is not limited to these embodiments: Example 1

[0041] A multifunctional superfabric for radiation cooling, the preparation method of which includes the following steps:

[0042] S1. Take polytetrafluoroethylene emulsion, binder and thickener in a mass ratio of 10:15:1.5, stir evenly to obtain color paste;

[0043] S2. After uniformly printing the color paste onto pretreated commercial cotton, aerogel is loaded onto the fabric surface to obtain printed superfabric. After pre-drying at 60℃ for 5 min, it is baked at 120℃ for 5 min to obtain a multifunctional superfabric for radiation cooling.

[0044] The preparation method of titanium dioxide aerogel in S2 includes the following steps:

[0045] S1-1. After mixing tetrabutyl titanate and glacial acetic acid, add it to anhydrous ethanol. The volume ratio of glacial acetic acid to anhydrous ethanol is 1:5. After stirring, a tetrabutyl titanate solution A with a mass fraction of 55 wt% is obtained.

[0046] S1-2. Mix water and anhydrous ethanol at a volume ratio of 1:2 until homogeneous, then add concentrated hydrochloric acid to adjust the pH to 1, and stir until homogeneous to obtain solution B;

[0047] S1-3. Slowly add solution B to solution A, then add sheet-like electrospun fiber membrane, and stir magnetically for 1 hour to obtain gel;

[0048] S1-4. Place the gel obtained in S1-3 in a magnetic field for 100 min, and then remove the device to obtain a gel oriented along the direction of the sheet-like statically spun fiber membrane;

[0049] S1-5. Orient the gel obtained in S1-4 at -40℃ and freeze-dry for 12 h to obtain titanium dioxide aerogel;

[0050] In step S1-3, the method for preparing the sheet-like electrospun fiber membrane includes the following steps:

[0051] S2-1. Take tetrabutyl titanate and glacial acetic acid in a molar ratio of 1:1 and stir magnetically at 40°C to obtain a homogeneous solution.

[0052] S2-2. Add magnetic core-shell particles to the solution obtained in S2-1 and disperse them ultrasonically to obtain an electrospinning solution with a mass fraction of 5 wt%.

[0053] S2-3. Electrospinning was performed using the electrospinning solution obtained in S2-2 at a voltage of 15kV and a flow rate of 1 mL / h to obtain an electrospinned fiber membrane.

[0054] S2-4. The electrospun fiber membrane obtained in S2-3 is pulverized to obtain a size of 1 mm.2 Sheet-like electrospun fiber membrane;

[0055] In step S2-2, the method for preparing magnetic core-shell particles includes the following steps:

[0056] S3-1. Take terephthalic acid and zinc acetate dihydrate in a mass ratio of 0.2:1 and add them to a solution of triethylamine, DMF and ethanol in a volume ratio of 1:3:14 to obtain a mixed solution;

[0057] S3-2. Add the Fe3O4 suspension and BaSO4 suspension with a volume ratio of 1:2 and a concentration ratio of 1:1 to the mixed solution obtained in S3-1, and stir magnetically for 3 h;

[0058] S3-3. After centrifuging and washing the product obtained in S3-2, Fe3O4@MOF-5@BaSO4 was obtained. The particles were then dispersed in water to obtain suspension A.

[0059] S3-4. Mix water with titanium trichloride precursor at a volume ratio of 20:1 until homogeneous, then add sodium bicarbonate solution with a concentration of 1 mol / L to adjust the pH to 2 to obtain solution B;

[0060] S3-5. The suspension A obtained in S3-3 is added to the solution B obtained in S3-4. The molar ratio of Fe3O4@MOF-5@BaSO4 to the ferric chloride precursor in solution B is 1:1. After reacting for 10 min, the core-shell magnetic particles are obtained by centrifugation, washing and drying.

[0061] Example 2

[0062] A multifunctional superfabric for radiation cooling, the preparation method of which includes the following steps:

[0063] S1. Take polytetrafluoroethylene emulsion, binder and thickener in a mass ratio of 30:25:3, stir evenly to obtain color paste;

[0064] S2. After uniformly printing the color paste onto pretreated commercial cotton, aerogel is loaded onto the fabric surface to obtain printed superfabric. After pre-drying at 80℃ for 10 min, it is baked at 150℃ for 10 min to obtain a multifunctional superfabric for radiation cooling.

[0065] The preparation method of titanium dioxide aerogel in S2 includes the following steps:

[0066] S1-1. After mixing tetrabutyl titanate and glacial acetic acid, add it to anhydrous ethanol. The volume ratio of glacial acetic acid to anhydrous ethanol is 3:15. After stirring, a tetrabutyl titanate solution A with a mass fraction of 70 wt% is obtained.

[0067] S1-2. Take water and anhydrous ethanol with a volume ratio of 3:4 and mix them evenly. Then add concentrated hydrochloric acid to adjust the pH to 3 and stir evenly to obtain solution B.

[0068] S1-3. Slowly add solution B to solution A, then add sheet-like electrospun fiber membrane, and stir magnetically for 3 hours to obtain gel;

[0069] S1-4. Place the gel obtained in S1-3 in a magnetic field for 500 min, and then remove the device to obtain a gel oriented along the direction of the sheet-like statically spun fiber membrane.

[0070] S1-5. Orient the gel obtained in S1-4 at -20℃ and freeze-dry for 20h to obtain titanium dioxide aerogel;

[0071] In step S1-3, the method for preparing the sheet-like electrospun fiber membrane includes the following steps:

[0072] S2-1. Take tetrabutyl titanate and glacial acetic acid in a molar ratio of 2.5:2.8 and stir magnetically at 60°C to obtain a homogeneous solution.

[0073] S2-2. Add magnetic core-shell particles to the solution obtained in S2-1 and disperse them ultrasonically to obtain an electrospinning solution with a mass fraction of 20 wt%.

[0074] S2-3. Electrospinning was performed using the electrospinning solution obtained in S2-2 at a voltage of 20 kV and a flow rate of 1.5 mL / h to obtain an electrospun fiber membrane;

[0075] S2-4. The electrospun fiber membrane obtained in S2-3 is pulverized to obtain a size of 2mm. 2 Sheet-like electrospun fiber membrane;

[0076] In step S2-2, the method for preparing magnetic core-shell particles includes the following steps:

[0077] S3-1. Take terephthalic acid and zinc acetate dihydrate in a mass ratio of 0.6:1 and add them to a triethylamine, DMF and ethanol solution in a volume ratio of 3:15:20 to obtain a mixed solution;

[0078] S3-2. Add the Fe3O4 suspension and BaSO4 suspension with a volume ratio of 3:5 and a concentration ratio of 4:9 to the mixed solution obtained in S3-1, and stir magnetically for 3 h;

[0079] S3-3. After centrifuging and washing the product obtained in S3-2, Fe3O4@MOF-5@BaSO4 was obtained. The particles were then dispersed in water to obtain suspension A.

[0080] S3-4. Mix water at a volume ratio of 20:1 with titanium trichloride precursor until homogeneous, then add sodium bicarbonate solution with a concentration of 3 mol / L to adjust the pH to 5 to obtain solution B;

[0081] S3-5. The suspension A obtained in S3-3 was added to the solution B obtained in S3-4. The molar ratio of Fe3O4@MOF-5@BaSO4 to the ferric chloride precursor in solution B was 15:70. After reacting for 50 min, the core-shell structured magnetic particles were obtained by centrifugation, washing and drying.

[0082] Example 3

[0083] A multifunctional superfabric for radiation cooling, the preparation method of which includes the following steps:

[0084] S1. Take polytetrafluoroethylene emulsion, binder and thickener in a mass ratio of 15:23:3, stir evenly to obtain color paste;

[0085] S2. After uniformly printing the color paste onto pretreated commercial cotton, aerogel is loaded onto the fabric surface to obtain printed superfabric. After pre-drying at 70℃ for 8 minutes, it is baked at 130℃ for 10 minutes to obtain a multifunctional superfabric for radiation cooling.

[0086] The preparation method of titanium dioxide aerogel in S2 includes the following steps:

[0087] S1-1. After mixing tetrabutyl titanate and glacial acetic acid, add them to anhydrous ethanol. The volume ratio of glacial acetic acid to anhydrous ethanol is 3:15. After stirring, a tetrabutyl titanate solution A with a mass fraction of 60 wt% is obtained.

[0088] S1-2. Take water and anhydrous ethanol with a volume ratio of 2:3 and mix them evenly. Then add concentrated hydrochloric acid to adjust the pH to 2 and stir evenly to obtain solution B.

[0089] S1-3. Slowly add solution B to solution A, then add sheet-like electrospun fiber membrane, and stir magnetically for 3 hours to obtain gel;

[0090] S1-4. Place the gel obtained in S1-3 in a magnetic field for 400 min, and then remove the device to obtain a gel oriented along the direction of the sheet-like statically spun fiber membrane;

[0091] S1-5. The gel obtained in S1-4 was oriented at -30℃ and freeze-dried for 20h to obtain titanium dioxide aerogel;

[0092] In step S1-3, the method for preparing the sheet-like electrospun fiber membrane includes the following steps:

[0093] S2-1. Take tetrabutyl titanate and glacial acetic acid in a molar ratio of 2:2.8 and stir magnetically at 50°C to obtain a homogeneous solution.

[0094] S2-2. Add magnetic core-shell particles to the solution obtained in S2-1 and disperse them ultrasonically to obtain an electrospinning solution with a mass fraction of 15 wt%.

[0095] S2-3. Electrospinning was performed using the electrospinning solution obtained in S2-2 at a voltage of 18 kV and a flow rate of 1.3 mL / h to obtain an electrospun fiber membrane;

[0096] S2-4. The electrospun fiber membrane obtained in S2-3 is pulverized to obtain a size of 2mm. 2 Sheet-like electrospun fiber membrane;

[0097] In step S2-2, the method for preparing magnetic core-shell particles includes the following steps:

[0098] S3-1. Take terephthalic acid and zinc acetate dihydrate in a mass ratio of 0.5:1 and add them to a solution of triethylamine, DMF and ethanol in a volume ratio of 3:15:20 to obtain a mixed solution;

[0099] S3-2. Add the Fe3O4 suspension and ZnO2 suspension with a volume ratio of 3:5 and a concentration ratio of 2:9 to the mixed solution obtained in S3-1, and stir magnetically for 3 h;

[0100] S3-3. After centrifuging and washing the product obtained in S3-2, Fe3O4@MOF-5@ZnO2 was obtained. The particles were then dispersed in water to obtain suspension A.

[0101] S3-4. Mix water with titanium trichloride precursor at a volume ratio of 20:1 until homogeneous, then add sodium bicarbonate solution with a concentration of 2 mol / L to adjust the pH to 5 to obtain solution B;

[0102] S3-5. The suspension A obtained in S3-3 was added to the solution B obtained in S3-4. The molar ratio of Fe3O4@MOF-5@BaSO4 to the ferric chloride precursor in solution B was 13:70. After reacting for 50 min, the core-shell magnetic particles were obtained by centrifugation, washing and drying.

[0103] Example 4

[0104] A multifunctional superfabric for radiation cooling, the preparation method of which includes the following steps:

[0105] S1. Take polytetrafluoroethylene emulsion, binder and thickener in a mass ratio of 20:17:2, stir evenly to obtain color paste;

[0106] S2. After uniformly printing the color paste onto pretreated commercial cotton, aerogel is loaded onto the fabric surface to obtain printed superfabric. After pre-drying at 75℃ for 8 minutes, it is baked at 160℃ for 10 minutes to obtain a multifunctional superfabric for radiation cooling.

[0107] The preparation method of titanium dioxide aerogel in S2 includes the following steps:

[0108] S1-1. After mixing tetrabutyl titanate and glacial acetic acid, add them to anhydrous ethanol. The volume ratio of glacial acetic acid to anhydrous ethanol is 3:15. After stirring, a tetrabutyl titanate solution A with a mass fraction of 60 wt% is obtained.

[0109] S1-2. Mix water and anhydrous ethanol in a volume ratio of 2:3 until homogeneous, then add concentrated hydrochloric acid to adjust the pH to 3, and stir until homogeneous to obtain solution B;

[0110] S1-3. Slowly add solution B to solution A, then add sheet-like electrospun fiber membrane, and stir magnetically for 3 hours to obtain gel;

[0111] S1-4. Place the gel obtained in S1-3 in a magnetic field for 200 min, and then remove the device to obtain a gel oriented along the direction of the sheet-like statically spun fiber membrane;

[0112] S1-5. The gel obtained in S1-4 was oriented at -35℃ and freeze-dried for 18 h to obtain titanium dioxide aerogel;

[0113] In step S1-3, the method for preparing the sheet-like electrospun fiber membrane includes the following steps:

[0114] S2-1. Take tetrabutyl titanate and glacial acetic acid in a molar ratio of 2:2.3 and stir magnetically at 50°C to obtain a homogeneous solution.

[0115] S2-2. Add magnetic core-shell particles to the solution obtained in S2-1 and disperse them ultrasonically to obtain an electrospinning solution with a mass fraction of 20 wt%.

[0116] S2-3. Electrospinning was performed using the electrospinning solution obtained in S2-2 at a voltage of 18 kV and a flow rate of 1.5 mL / h to obtain an electrospun fiber membrane.

[0117] S2-4. The electrospun fiber membrane obtained in S2-3 is pulverized to obtain a size of 1.5 mm. 2 Sheet-like electrospun fiber membrane;

[0118] In step S2-2, the method for preparing magnetic core-shell particles includes the following steps:

[0119] S3-1. Take terephthalic acid and zinc acetate dihydrate in a mass ratio of 0.5:1 and add them to a solution of triethylamine, DMF and ethanol in a volume ratio of 3:15:20 to obtain a mixed solution;

[0120] S3-2. Add the Fe3O4 suspension and TiO2 suspension with a volume ratio of 2:5 and a concentration ratio of 2:9 to the mixed solution obtained in S3-1, and stir magnetically for 3 hours;

[0121] S3-3. After centrifuging and washing the product obtained in S3-2, Fe3O4@MOF-5@TiO2 was obtained. The particles were then dispersed in water to obtain suspension A.

[0122] S3-4. Take water with a volume ratio of 20:1 and mix it evenly with titanium trichloride precursor, then add sodium bicarbonate solution with a concentration of 2.5 mol / L to adjust the pH to 5 to obtain solution B;

[0123] S3-5. The suspension A obtained in S3-3 was added to the solution B obtained in S3-4. The molar ratio of Fe3O4@MOF-5@TiO2 to the ferric chloride precursor in solution B was 10:65. After reacting for 40 min, the core-shell magnetic particles were obtained by centrifugation, washing and drying.

[0124] Example 5

[0125] A multifunctional superfabric for radiation cooling, the preparation method of which includes the following steps:

[0126] S1. Take polytetrafluoroethylene emulsion, binder and thickener in a mass ratio of 25:25:2, stir evenly to obtain color paste;

[0127] S2. After uniformly printing the color paste onto pretreated commercial cotton, aerogel is loaded onto the fabric surface to obtain printed superfabric. After pre-drying at 65℃ for 8 minutes, it is baked at 160℃ for 9 minutes to obtain a multifunctional superfabric for radiation cooling.

[0128] The preparation method of titanium dioxide aerogel in S2 includes the following steps:

[0129] S1-1. After mixing tetrabutyl titanate and glacial acetic acid, add it to anhydrous ethanol. The volume ratio of glacial acetic acid to anhydrous ethanol is 3:15. After stirring, a tetrabutyl titanate solution A with a mass fraction of 65 wt% is obtained.

[0130] S1-2. Mix water and anhydrous ethanol in a volume ratio of 2:3 until homogeneous, then add concentrated hydrochloric acid to adjust the pH to 3, and stir until homogeneous to obtain solution B;

[0131] S1-3. Slowly add solution B to solution A, then add sheet-like electrospun fiber membrane, and stir magnetically for 3 h to obtain gel;

[0132] S1-4. Place the gel obtained in S1-3 in a magnetic field for 300 min, and then remove the device to obtain a gel oriented along the direction of the sheet-like statically spun fiber membrane;

[0133] S1-5. The gel obtained in S1-4 was oriented at -20℃ and freeze-dried for 16 h to obtain titanium dioxide aerogel;

[0134] In step S1-3, the method for preparing the sheet-like electrospun fiber membrane includes the following steps:

[0135] S2-1. Take tetrabutyl titanate and glacial acetic acid in a molar ratio of 2:2.8 and stir magnetically at 55°C to obtain a homogeneous solution.

[0136] S2-2. Add magnetic core-shell particles to the solution obtained in S2-1 and disperse them ultrasonically to obtain an electrospinning solution with a mass fraction of 15 wt%.

[0137] S2-3. Electrospinning was performed using the electrospinning solution obtained in S2-2 at a voltage of 20 kV and a flow rate of 1.2 mL / h to obtain an electrospun fiber membrane;

[0138] S2-4. The electrospun fiber membrane obtained in S2-3 is pulverized to obtain a size of 1 mm. 2 Sheet-like electrospun fiber membrane;

[0139] In step S2-2, the method for preparing magnetic core-shell particles includes the following steps:

[0140] S3-1. Take terephthalic acid and zinc acetate dihydrate in a mass ratio of 0.5:1 and add them to a solution of triethylamine, DMF and ethanol in a volume ratio of 2:13:17 to obtain a mixed solution;

[0141] S3-2. Add the Fe3O4 suspension and CaCO3 suspension with a volume ratio of 2:5 and a concentration ratio of 3:8 to the mixed solution obtained in S3-1, and stir magnetically for 3 h;

[0142] S3-3. After centrifuging and washing the product obtained in S3-2, Fe3O4@MOF-5@CaCO3 was obtained. The particles were then dispersed in water to obtain suspension A.

[0143] S3-4. Take water with a volume ratio of 20:1 and mix it evenly with titanium trichloride precursor, then add sodium bicarbonate solution with a concentration of 2.5 mol / L to adjust the pH to 5 to obtain solution B;

[0144] S3-5. The suspension A obtained in S3-3 was added to the solution B obtained in S3-4. The molar ratio of Fe3O4@MOF-5@CaCO3 to the ferric chloride precursor in solution B was 10:55. After reacting for 45 min, the core-shell magnetic particles were obtained by centrifugation, washing and drying.

[0145] Comparative Example 1

[0146] The difference between Comparative Example 1 and Example 5 is that no magnetic core-shell structured particles were added to the titanium dioxide aerogel.

[0147] A multifunctional superfabric for radiation cooling, the preparation method of which includes the following steps:

[0148] S1. Take polytetrafluoroethylene emulsion, binder and thickener in a mass ratio of 25:25:2, stir evenly to obtain color paste;

[0149] S2. After uniformly printing the color paste onto pretreated commercial cotton, aerogel is loaded onto the fabric surface to obtain printed superfabric. After pre-drying at 65 ℃ for 8 min, it is baked at 160 ℃ for 9 min to obtain a multifunctional superfabric for radiation cooling.

[0150] The preparation method of titanium dioxide aerogel in S2 includes the following steps:

[0151] S1-1. Tetrabutyl titanate and glacial acetic acid are mixed and then added to anhydrous ethanol. The volume ratio of glacial acetic acid to anhydrous ethanol is 3:15. After stirring, a tetrabutyl titanate solution A with a mass fraction of 65 wt% is obtained.

[0152] S1-2. Mix water and anhydrous ethanol in a volume ratio of 2:3 until homogeneous, then add concentrated hydrochloric acid to adjust the pH to 3, and stir until homogeneous to obtain solution B;

[0153] S1-3. Slowly add solution B to solution A, then add sheet-like electrospun fiber membrane, and stir magnetically for 3 h to obtain gel;

[0154] S1-4. Place the gel obtained in S1-3 in a magnetic field for 300 min, and then remove the device to obtain a gel oriented along the direction of the sheet-like statically spun fiber membrane;

[0155] S1-5. The gel obtained in S1-4 was oriented at -20℃ and freeze-dried for 16 h to obtain titanium dioxide aerogel;

[0156] In step S1-3, the method for preparing the sheet-like electrospun fiber membrane includes the following steps:

[0157] S2-1. Take tetrabutyl titanate and glacial acetic acid in a molar ratio of 2:2.8 and stir magnetically at 55°C to obtain a homogeneous solution.

[0158] S2-2. Add Fe3O4@MOF-5 particles and CaCO3 particles in a mass ratio of 1:1 to the solution obtained in S2-1 and disperse them by ultrasonication to obtain an electrospinning solution with a mass fraction of 15wt%.

[0159] S2-3. Electrospinning was performed using the electrospinning solution obtained in S2-2 at a voltage of 20 kV and a flow rate of 1.2 mL / h to obtain an electrospun fiber membrane;

[0160] S2-4. The electrospun fiber membrane obtained in S2-3 is pulverized to obtain a size of 1 mm. 2 Sheet-shaped electrospun fiber membrane.

[0161] Comparative Example 2

[0162] The difference between Comparative Example 2 and Example 5 is that magnetic core-shell particles were added to titanium dioxide aerogel instead of sheet-like electrospun membrane.

[0163] Comparative Example 3

[0164] The difference between Comparative Example 3 and Example 5 is that the sheet-like electrospun fiber membrane in the titanium dioxide aerogel is not oriented.

[0165] Comparative Example 4

[0166] The difference between Comparative Example 4 and Example 5 is that titanium dioxide aerogel is dispersed in the adhesive layer for scraping.

[0167] Comparative Example 5

[0168] The difference between Comparative Example 5 and Example 5 is that the titanium dioxide aerogel was not subjected to directional freeze-drying.

[0169] Performance testing

[0170] The performance of the samples prepared in Examples 1-5 and Comparative Examples 1-5 of the present invention will be tested below.

[0171] As shown in Table 1, compared with the comparative example, the multifunctional superfabric radiation cooling coatings of each embodiment have better cooling effect and longer service life, with an emissivity of greater than 95% in the 8 μm-13 μm range and a reflectivity of greater than 96% in the 0.3 μm-2.5 μm range.

[0172] Table 1. Emissivity and Reflectivity of Samples

[0173]

[0174] As shown in Table 2, the test results of Example 5 are the best, demonstrating good flame retardant and waterproof effects.

[0175] Table 2 Flame retardancy and waterproof test results

[0176]

[0177] As shown in Table 3, Example 5 has the best antibacterial effect, with an antibacterial rate of 98.72% against Staphylococcus aureus.

[0178] Table 3 Antibacterial performance tests of different samples

[0179]

[0180] Note:

[0181] 1. AM1.5 Solar Spectral Reflectance Test: The spectral reflectance obtained in the 200-2500 nm band was tested and characterized. The test instrument used was the Shimadzu UV3600 from Japan, and the standard backplane used for the test was a BaSO4 backplane.

[0182] 2.8μm-13μm band emissivity test method: Infrared spectroscopy was used for testing. The test instrument was a Fourier transform infrared spectrometer. The infrared emissivity in the 8μm-13μm band was tested at a test interval of 1nm. The emissivity in the 8μm-13μm band is the atmospheric window emissivity.

[0183] 3. Refrigeration performance evaluation: Temperature measurements were all recorded using TA612C thermocouples, and the relative error between thermocouples was less than 0.5℃. See [link / reference] Figure 1 The measuring device includes a polystyrene foam box wrapped in aluminum foil to minimize heat transfer and sunlight reflection. The test fabric sample is visualized in real time using an infrared thermal imager (UTi320E). Combined with a real human outdoor experiment, volunteers wearing the test sample (the left and right sides of the clothing are made of different fabrics, i.e., one side is superfabric and the other side is pure cotton) face the direction of sunlight. Thermocouples are used to record the temperature of the different fabrics and the skin temperature with and without superfabric coverage. The environmental conditions on the day of the experiment, such as temperature, humidity, wind speed, and solar radiation power, are also recorded.

[0184] 4. Flame retardancy test: The vertical burning of the microfiber fabric is tested according to the national standard GB / T5455 and the limiting oxygen index of the microfiber fabric is tested according to CB / T5454.

[0185] 5. Waterproofing test: The contact angle of the superfabric was tested using a contact angle measuring instrument; the hydrostatic pressure resistance of the superfabric was tested using a YG(B)812Q textile hydrostatic pressure tester in accordance with GB / T4744—2013 "Test and evaluation of waterproof performance of textiles - hydrostatic pressure test".

[0186] 6. Antibacterial test: The antibacterial properties of the microfiber fabric were tested according to the national standard GB / T 20944.

[0187] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A multifunctional superfabric for radiative cooling, characterized in that: The fabric comprises a fabric layer, an adhesive layer and an aerogel layer. The fabric layer and the aerogel layer are composited by the adhesive layer. The aerogel layer is a titanium dioxide aerogel with a three-dimensional tubular structure and a sheet-like electrospun fiber membrane containing magnetic core-shell particles loaded on the skeleton. The method for preparing the multifunctional superfabric for radiation cooling includes the following steps: S1. Take polytetrafluoroethylene emulsion, binder and thickener in a mass ratio of 10~30:15~25:1.5~3, stir evenly to obtain color paste; S2. After uniformly printing the color paste onto the pretreated fabric, titanium dioxide aerogel is loaded onto the fabric surface to obtain printed superfabric. After pre-baking, it is baked to obtain a multifunctional superfabric for radiation cooling. The preparation method of the titanium dioxide aerogel in S2 includes the following steps: S1-1. Tetrabutyl titanate and glacial acetic acid are mixed and then added to anhydrous ethanol and stirred to obtain homogeneous solution A; S1-2. Take water with a volume ratio of 1~3:2~4 and anhydrous ethanol and mix them evenly. Then add concentrated hydrochloric acid to adjust the pH to 1~3 and stir evenly to obtain solution B. S1-3. Slowly add solution B to homogeneous solution A, then add sheet-like electrospun fiber membrane, and stir magnetically for 1-3 hours to obtain gel; S1-4. Place the gel obtained in S1-3 in a magnetic field for 100~500 min, and then remove the device to obtain a gel oriented along the direction of the sheet-like statically spun fiber membrane; S1-5. Orient the gel obtained in S1-4 at -40~-20℃ and freeze-dry for 12~20h to obtain titanium dioxide aerogel; The method for preparing the sheet-like electrospun fiber membrane in S1-3 includes the following steps: S2-1. Take tetrabutyl titanate and glacial acetic acid in a molar ratio of 1~2.5:1~2.8 and stir magnetically at 40~60℃ to obtain a homogeneous solution; S2-2. Add magnetic core-shell particles to the solution obtained in S2-1 and disperse them ultrasonically to obtain an electrospinning solution with a mass fraction of 5~20wt%; S2-3. Electrospinning is performed using the electrospinning solution obtained in S2-2 at a voltage of 15~20kV and a flow rate of 1~1.5mL / h to obtain an electrospun fiber membrane; S2-4. The electrospun fiber membrane obtained in S2-3 is pulverized to obtain a size of 1~2 mm. 2 Sheet-shaped electrospun fiber membrane.

2. The multifunctional superfabric for radiation cooling according to claim 1, characterized in that: The pretreated fabric is one of commercial cotton, polyester, nylon, linen, silk or spandex fabrics. The pre-drying time is 5-10 minutes, the pre-drying temperature is 60-80℃, the baking time is 5-10 minutes, and the baking temperature is 120-150℃.

3. The multifunctional superfabric for radiation cooling according to claim 1, characterized in that: In S1-1, the mass of tetrabutyl titanate is 55-70% of that of solution A, and the volume ratio of glacial acetic acid to anhydrous ethanol is 1-3:5-15.

4. The multifunctional superfabric for radiation cooling according to claim 1, characterized in that: The method for preparing the magnetic core-shell particles in S2-2 includes the following steps: S3-1. Take terephthalic acid and zinc acetate dihydrate in a mass ratio of 0.2~0.6:1 and add them to a solution of triethylamine, DMF and ethanol in a volume ratio of 1~3:3~15:14~20 to obtain a mixed solution; S3-2. Add the Fe3O4 suspension and inorganic particle suspension with a volume ratio of 1~3:2~5 to the mixed solution obtained in S3-1, and stir magnetically for 3 hours; S3-3. After centrifuging and washing the product obtained in S3-2, Fe3O4@MOF-5@inorganic particles were obtained. The particles were then dispersed in water to obtain suspension A. S3-4. Mix water at a volume ratio of 20:1 with titanium trichloride precursor until homogeneous, then add sodium bicarbonate solution with a concentration of 1~3 mol / L to adjust the pH to 2~5 to obtain solution B; S3-5. Add the suspension A obtained in S3-3 to the solution B obtained in S3-4 and react for 10-50 min. After centrifugation, washing and drying, magnetic core-shell particles are obtained.

5. The multifunctional superfabric for radiation cooling according to claim 4, characterized in that: The concentration ratio of Fe3O4 suspension to inorganic particle suspension in S3-2 is 1~4:1~9. The inorganic particle suspension is one or more of BaSO4 suspension, CaCO3 suspension, Al2O3 suspension, TiO2 suspension, ZnO2 suspension, AlPO4 suspension, hollow glass microsphere suspension or SiC suspension.

6. The multifunctional superfabric for radiation cooling according to claim 4, characterized in that: The ratio of Fe3O4@MOF-5@inorganic particles in suspension A to ferric chloride precursor in solution B in S3-5 is 1:15 to 1:70.

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