Preparation method for ultra-high reflectivity radiative cooling fiber membrane
By adjusting the electrospinning parameters, porous PVDF-HFP fiber membranes were prepared, solving the problem of insufficient reflectivity in existing technologies. This resulted in a radiation-cooling fiber membrane with ultra-high reflectivity, exhibiting excellent cooling performance and broad application prospects.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- BEIJING UNIV OF CHEM TECH
- Filing Date
- 2026-01-09
- Publication Date
- 2026-07-16
Smart Images
Figure CN2026071649_16072026_PF_FP_ABST
Abstract
Description
A method for preparing an ultra-high reflectivity radiation-cooling fiber membrane Technical Field
[0001] This application relates to the field of radiation cooling technology, specifically a radiation cooling fiber membrane with ultra-high reflectivity across the entire solar spectrum from ultraviolet to visible to near-infrared. Background Technology
[0002] Global warming has become one of the major environmental problems and development challenges facing humanity in the 21st century. Currently, over 10% of global greenhouse gas emissions come from traditional refrigeration equipment. The number of air conditioners and other refrigeration devices in use worldwide has exceeded 3.6 billion, consuming enormous amounts of electricity. This electricity is primarily generated from the combustion of fossil fuels, leading to a continuous increase in greenhouse gas emissions, exacerbating global warming, and creating a vicious cycle. To break this situation, passive radiative cooling technology has emerged.
[0003] Unlike traditional refrigeration methods, passive radiant cooling is a green refrigeration method that requires no external energy, no refrigerant, and emits no carbon during operation. It has garnered increasing attention, and related scientific research and technological applications have become a focus of academic and industrial attention in recent years. This technology can effectively reduce the need for traditional cooling equipment such as fans and air conditioners, and it also has significant application potential in human thermal management.
[0004] Excellent passive radiative cooling devices should have sufficiently high reflectivity in the solar radiation band (0.3-2.5 μm) to reduce energy absorption from sunlight; in addition, they should also have high emissivity in the atmospheric window band (8-13 μm) to achieve energy-free cooling. However, for radiative cooling technology, the key to its daytime cooling performance lies in high reflectivity. Even with 100% emissivity, only a few percentage points of solar absorption are needed to effectively heat an object, thus significantly reducing the cooling effect. However, in most studies, reflectivity is difficult to exceed 95%. Patent CN117822136A discloses the use of an integrated spray gun for wet blowing to prepare fiber membranes, which is convenient, fast, and safe to operate, but the micro-nano structure control of the fiber membrane is poor, with an average reflectivity of less than 82% in the solar radiation band; Patent CN114293366A discloses a radiative cooling fiber membrane doped with titanium oxide particles, with an average reflectivity of less than 92.3% in the solar radiation band, which has certain limitations. Summary of the Invention
[0005] This application addresses the limitation of current radiative coolers having low reflectivity by providing a method for preparing a radiative cooling fiber membrane with ultra-high reflectivity across the entire solar spectrum, from ultraviolet to visible to near-infrared.
[0006] The method for preparing an ultra-high reflectivity radiation-cooling fiber membrane is as follows: a polymer is dissolved in an organic solvent to prepare an electrospinning precursor solution. By reasonably adjusting parameters such as the concentration of the electrospinning precursor solution, the electrospinning voltage, the spinning distance, the roller speed, the spinning liquid supply rate, and the slide rail reciprocating speed, an ultra-high reflectivity radiation-cooling fiber membrane with a porous structure is prepared. The reflectivity of the ultra-high reflectivity radiation-cooling fiber membrane is greater than 95% in the solar light band of 0.3-2.5 μm. During the preparation process, the spinning time, ambient temperature and humidity, and light conditions can also be controlled.
[0007] This application discloses a method for preparing an ultra-high reflectivity radiation-cooling fiber membrane. The ultra-high reflectivity radiation-cooling fiber membrane uses polymers including, but not limited to, one or more of the following polymers: polyvinylidene fluoride hexafluoropropylene (PVDF-HFP), polyvinylidene fluoride (PVDF), polylactic acid (PLA), polyoxyethylene (PEO), polymethyl methacrylate (PMMA), polydimethylsiloxane (PDMS), polyurethane (TPU), polystyrene (PS), polyoxymethylene (POM), polytetrafluoroethylene (PTFE), and polyvinyl alcohol (PVA).
[0008] This application discloses a method for preparing an ultra-high reflectivity radiation-cooling fiber membrane, wherein the organic solvent includes, but is not limited to, one or more organic solvents such as acetone, N,N-dimethylformamide (DMF), chloroform, tetrahydrofuran, and dichloromethane.
[0009] Preferably, the polymer is a fluorinated polymer such as PVDF-HFP, and its mass fraction in the electrospinning precursor solution is 12wt%-16wt%.
[0010] Preferably, the organic solvent is a mixed solution of acetone and N,N dimethylformamide, wherein the mass ratio of acetone to N,N dimethylformamide is 1:1.
[0011] Preferably, the water bath stirring temperature during the dissolution process is 20-60℃, and the stirring time is 3-6 hours.
[0012] Preferably, the electrospinning adopts a double-sided multi-nozzle opposing layout.
[0013] Preferably, the spinning distance is 15-30cm.
[0014] Preferably, the electrospinning voltage is 20-50kV.
[0015] Preferably, the drum rotation speed is 400-1000 r / min.
[0016] Preferably, the spinning liquid supply rate is 8-30 mL / h.
[0017] Preferably, the reciprocating speed of the slide rail is 3-10 mm / s.
[0018] Preferably, the spinning time is 1-6 hours; the thickness of the ultra-high reflectivity radiation cooling fiber film is 300-500 μm.
[0019] This application discloses a method for preparing an ultra-high reflectivity radiation-cooling fiber membrane, which can be applied to clothing, construction, equipment and other fields.
[0020] Compared with the prior art, the beneficial effects of this application are as follows:
[0021] (1) This application prepares porous PVDF-HFP fiber membranes by double-sided multi-nozzle electrospinning technology. By changing the spinning parameters, the macro-micro structure of the fiber membrane can be precisely controlled, so that the prepared radiation cooling fiber membrane has ultra-high reflectivity in the solar light band and can achieve better cooling effect.
[0022] (2) The radiation cooling fiber membrane has advantages such as being able to be mass-produced, having low cost, and having good performance.
[0023] (3) The radiation cooling fiber membrane has good flexibility and a wide range of applications, and can be used in clothing, construction, equipment and other fields. Attached Figure Description
[0024] Figure 1 shows a method for preparing an ultra-high reflectivity radiation-cooling fiber membrane according to this application, and SEM images of the radiation-cooling fiber membranes obtained in Examples 1-3, (A) Example 1, (B) Example 2, (C) Example 3;
[0025] Figure 2A shows a method for preparing an ultra-high reflectivity radiation-cooling fiber membrane according to this application, and a diameter distribution diagram of the radiation-cooling fiber membrane obtained in Example 2.
[0026] Figure 2B shows a method for preparing an ultra-high reflectivity radiation-cooling fiber membrane according to this application, and the pore size diagram of the radiation-cooling fiber membrane obtained in Example 2. Detailed Implementation
[0027] To make the advantages, features, and objectives of this application more apparent and understandable, the technical solutions in the embodiments, comparative examples, and experimental examples of this application will be clearly and completely described below. Obviously, the described embodiments, comparative examples, and experimental examples are only a part of the embodiments, comparative examples, and experimental examples of this application, and not all of them. All other embodiments, comparative examples, and experimental examples obtained by those skilled in the art based on the embodiments, comparative examples, and experimental examples in this application without inventive effort are within the scope of protection of this disclosure.
[0028] Example 1
[0029] This application discloses a method for preparing an ultra-high reflectivity radiation-cooling fiber membrane, the specific preparation steps of which are as follows:
[0030] (1) Preparation of 12wt% PVDF-HFP electrospinning solution: 16.8g PVDF-HFP was dispersed in a mixed solvent of 123.2g acetone and DMF (the mass ratio of acetone to DMF was 1:1), and stirred in a water bath at 50℃ for 3 hours until completely dissolved to obtain 140g of electrospinning precursor solution with a concentration of 12wt%.
[0031] (2) Electrospinning: The electrospinning precursor solution in step (1) of this embodiment is poured into a syringe with a needle specification of 20G; the electrospinning voltage is 30kV; the roller speed is 700r / min; the spinning distance is 30cm; the spinning liquid supply rate is 12mL / h; and an ultra-high reflectivity radiation cooling fiber membrane sample with a thickness of 500μm is obtained.
[0032] Example 2
[0033] (1) Preparation of 16wt% PVDF-HFP electrospinning solution: 19.2g of PVDF-HFP was dispersed in a mixed solvent of 100.8g of acetone and DMF (where the mass ratio of acetone to DMF was 1:1) and stirred in a water bath at 50℃ for 3 hours until completely dissolved to obtain 120g of a 16wt% electrospinning solution.
[0034] (2) Electrospinning: Pour the spinning solution from step (1) of this embodiment into a syringe with a needle specification of 20G; spinning voltage of 30kV; roller speed of 700r / min; spinning distance of 30cm; spinning liquid supply rate of 20mL / h; and obtain a radiation cooling fiber membrane sample with a thickness of 500μm.
[0035] Example 3
[0036] (1) Preparation of 20wt% PVDF-HFP electrospinning solution: 20g PVDF-HFP was dispersed in a mixed solvent of 80g acetone and DMF (where the mass ratio of acetone to DMF was 1:1), and stirred in a water bath at 50℃ for 3 hours until completely dissolved to obtain 100g of a 20wt% electrospinning solution.
[0037] (2) Electrospinning: Pour the spinning solution from step (1) of this embodiment into a syringe with a needle specification of 20G; spinning voltage of 30kV; roller speed of 700r / min; spinning distance of 30cm; spinning liquid supply rate of 26mL / h; and obtain a radiation cooling fiber membrane sample with a thickness of 500μm.
[0038] Comparative Example 1
[0039] The preparation method of the radiation-cooling membrane provided in this comparative example is basically the same as that in Example 1, except that 112g of a spinning solution with a concentration of 12wt% is prepared and spun to obtain a radiation-cooling fiber membrane sample with a thickness of 400μm.
[0040] Comparative Example 2
[0041] The preparation method of the radiation-cooling membrane provided in this comparative example is basically the same as that in Example 1, except that 84g of a spinning solution with a concentration of 12wt% is prepared and spun to obtain a radiation-cooling fiber membrane sample with a thickness of 300μm.
[0042] Comparative Example 3
[0043] The preparation method of the radiation-cooling membrane provided in this comparative example is basically the same as that in Example 1, except that 56g of a spinning solution with a concentration of 12wt% is prepared and spun to obtain a radiation-cooling fiber membrane sample with a thickness of 200μm.
[0044] Comparative Example 4
[0045] The preparation method of the radiation-cooling membrane provided in this comparative example is basically the same as that in Example 1, except that 28g of a spinning solution with a concentration of 12wt% is prepared and spun to obtain a radiation-cooling fiber membrane sample with a thickness of 100μm.
[0046] Comparative Example 5
[0047] The preparation method of the radiation-cooling membrane provided in this comparative example is basically the same as that in Example 2, except that 96g of a spinning solution with a concentration of 16wt% is prepared and spun to obtain a radiation-cooling fiber membrane sample with a thickness of 400μm.
[0048] Comparative Example 6
[0049] The preparation method of the radiation-cooling membrane provided in this comparative example is basically the same as that in Example 2, except that 72g of a spinning solution with a concentration of 16wt% is prepared and spun to obtain a radiation-cooling fiber membrane sample with a thickness of 300μm.
[0050] Comparative Example 7
[0051] The preparation method of the radiation-cooling membrane provided in this comparative example is basically the same as that in Example 2, except that 48g of a spinning solution with a concentration of 16wt% is prepared and spun to obtain a radiation-cooling fiber membrane sample with a thickness of 200μm.
[0052] Comparative Example 8
[0053] The preparation method of the radiation-cooling membrane provided in this comparative example is basically the same as that in Example 2, except that 24g of a spinning solution with a concentration of 16wt% is prepared and spun to obtain a radiation-cooling fiber membrane sample with a thickness of 100μm.
[0054] Comparative Example 9
[0055] The preparation method of the radiation-cooling membrane provided in this comparative example is basically the same as that in Example 3, except that 80g of a spinning solution with a concentration of 20wt% is prepared and spun to obtain a radiation-cooling fiber membrane sample with a thickness of 400μm.
[0056] Comparative Example 10
[0057] The preparation method of the radiation-cooling membrane provided in this comparative example is basically the same as that in Example 3, except that 60g of a spinning solution with a concentration of 20wt% is prepared and spun to obtain a radiation-cooling fiber membrane sample with a thickness of 300μm.
[0058] Comparative Example 11
[0059] The preparation method of the radiation-cooling membrane provided in this comparative example is basically the same as that in Example 3, except that 40g of a spinning solution with a concentration of 20wt% is prepared and spun to obtain a radiation-cooling fiber membrane sample with a thickness of 200μm.
[0060] Comparative Example 12
[0061] The preparation method of the radiation-cooling membrane provided in this comparative example is basically the same as that in Example 3, except that 20g of a spinning solution with a concentration of 20wt% is prepared and spun to obtain a radiation-cooling fiber membrane sample with a thickness of 100μm.
[0062] Experimental Example 1
[0063] After sputtering gold onto the surface of the samples prepared in the examples, the surface morphology of the radiation-cooling fiber membranes obtained in Examples 1-3 was characterized using a field emission scanning electron microscope (Hitachi S4700). The SEM images are shown in Figure 1 (A)-(C).
[0064] The fiber diameter was measured using Image-J image analysis software on SEM images, and the fiber diameter distribution of the three PVDF-HFP mass fraction samples was statistically analyzed. The average fiber diameters of the fiber membranes obtained in Examples 1-3 were 0.35±0.11 μm, 0.57±0.15 μm, and 1.05±0.17 μm, respectively. The fiber diameter and pore size distribution of Example 2 are shown in Figures 2A and 2B.
[0065] The pore size of the ultra-high reflectivity radiation-cooling fiber membrane was measured using a capillary pore size analyzer, and the pore size distribution of the three mass fraction PVDF-HFP samples was statistically analyzed. The average pore sizes of the ultra-high reflectivity radiation-cooling fiber membranes obtained in Examples 1-3 were 0.65±0.23 μm, 0.71±0.15 μm, and 0.95±0.61 μm, respectively.
[0066] Experimental Example 2
[0067] The radiation-cooled fiber membrane samples prepared in each embodiment and the radiation-cooled fiber membrane samples prepared in each comparative example were subjected to the following performance tests.
[0068] The reflectance spectra of the radiation-cooled fiber membrane samples prepared in each example and comparative example in the solar radiation band (0.3-2.5 μm) were measured using a UV-VIS-NIR spectrophotometer equipped with a BaSO4 integrating sphere.
[0069] The emissivity spectra of the radiation-cooled fiber membrane samples prepared in each embodiment and comparative example were measured in the atmospheric window band (8-13 μm) using a Fourier transform infrared spectrometer (Nicolet iS50) equipped with a gold integrating sphere.
[0070] The weighted average of the reflectivity and emissivity test results is calculated, and the results are shown in Table 1.
[0071] Table 1 Weighted average reflectivity and emissivity
[0072] As shown in Table 1, the radiation cooling performance of the sample in Example 2 is more advantageous than that of other examples and comparative examples.
[0073] Experiment 3: Daytime cooling performance test.
[0074] The cooling performance of the prepared fiber membrane was tested using a radiation-cooled temperature measurement device. A 4-hour (10:00-14:00) continuous outdoor temperature measurement was conducted on October 2, 2024, at Beijing University of Chemical Technology, under an average solar irradiance of 820 W / m². 2 Under the specified conditions, the cooling effects of Example 2, Comparative Example 2, Comparative Example 4, and a white cloth with a thickness of 500 μm were tested. The white cloth had an average temperature rise of 3.9 °C, while the average cooling temperature of the radiation-cooling fiber membrane with an average thickness of only 100 μm reached 4.9 °C; the average cooling temperature of the radiation-cooling fiber membrane with an average thickness of 300 μm reached 8.4 °C; and the average cooling temperature of the radiation-cooling fiber membrane with a thickness of 500 μm reached 10.3 °C.
[0075] Experiment 4 is an infrared thermal imaging test.
[0076] The temperature changes of Example 2, Comparative Example 2, Comparative Example 4, and a 500μm thick white cloth wrapped around a stainless steel box and the surface of human skin were compared using an infrared thermal imager. The results are shown in Tables 2 and 3, respectively.
[0077] Table 2. Surface Temperature Changes of Stainless Steel Boxes
[0078] Table 3 Changes in human skin surface temperature
[0079] Whether covering the surface of a stainless steel box or the surface of human skin, the temperature of the high reflectivity radiation cooling fiber membrane is lower than that of the white cloth under the same conditions, indicating that the ultra-high reflectivity radiation cooling fiber membrane described in this application has excellent performance and can be used for spontaneous cooling with zero energy consumption and zero carbon emissions in fields such as construction, equipment and clothing.
[0080] This application utilizes electrospinning to prepare a radiation-cooling fiber membrane with ultra-high reflectivity (up to 99.39%) by controlling the thickness and micro / nano structure of the fiber membrane.
[0081] Although the above embodiments have provided a detailed description of this application, they are only some embodiments of this application, not all embodiments. Other embodiments can be obtained based on these embodiments without creative intent, and these embodiments all fall within the protection scope of this application.
Claims
1. A method for preparing an ultra-high reflectivity radiation-cooling fiber membrane, characterized in that: A polymer is dissolved in an organic solvent to prepare an electrospinning precursor solution. By adjusting the concentration of the electrospinning precursor solution, the electrospinning voltage, the spinning distance, the roller speed, the spinning liquid supply rate, and the slide rail reciprocating speed, an ultra-high reflectivity radiation-cooling fiber membrane with a porous structure is prepared. The ultra-high reflectivity radiation-cooling fiber membrane has a reflectivity greater than 95% in the solar light band of 0.3-2.5 μm. The polymer includes one or more of polyvinylidene fluoride hexafluoropropylene, polyvinylidene fluoride, polylactic acid, polyoxyethylene, polymethyl methacrylate, polydimethylsiloxane, polyurethane, polystyrene, polyoxymethylene, polytetrafluoroethylene, and polyvinyl alcohol. The organic solvent includes one or more of acetone, N,N dimethylformamide, chloroform, tetrahydrofuran, and dichloromethane; the dissolution is carried out under water bath stirring conditions, the water bath stirring temperature is 20-60℃, the stirring time is 3-6h, the electrospinning adopts a double-sided multi-nozzle opposing layout, the spinning distance is 15-30cm, the electrospinning voltage is 20-50kV, the roller speed is 400-1000r / min, the spinning liquid supply rate is 8-30mL / h, the slide rail reciprocating speed is 3-10mm / s, and the thickness of the ultra-high reflectivity radiation cooling fiber membrane is 300-500μm.
2. The method for preparing an ultra-high reflectivity radiation-cooling fiber membrane according to claim 1, characterized in that: The polymer is polyvinylidene fluoride hexafluoropropylene, and the concentration of the polymer in the electrospinning precursor solution is 12wt%-16wt% or 20wt%.
3. The method for preparing an ultra-high reflectivity radiation-cooling fiber membrane according to claim 1, characterized in that: The organic solvent is a mixture of acetone and N,N dimethylformamide.
4. The method for preparing an ultra-high reflectivity radiation-cooling fiber membrane according to claim 3, characterized in that: The mass ratio of acetone to N,N-dimethylformamide in the mixed solvent is 1:
1.
5. The method for preparing an ultra-high reflectivity radiation-cooling fiber membrane according to claim 1, characterized in that: The spinning time is 1-6 hours.
6. The method for preparing an ultra-high reflectivity radiation-cooling fiber membrane according to claim 1, characterized in that: The drum rotation speed is 700 r / min.
7. The method for preparing an ultra-high reflectivity radiation-cooling fiber membrane according to claim 1, characterized in that: The temperature of the water bath stirring is 50°C.
8. The method for preparing an ultra-high reflectivity radiation-cooling fiber membrane according to claim 1, characterized in that: The electrospinning voltage is 30kV.
9. The method for preparing an ultra-high reflectivity radiation-cooling fiber membrane according to claim 1, characterized in that: The spinning liquid supply rate is 12 mL / h, 20 mL / h, or 26 mL / h.
10. The ultra-high reflectivity radiation-cooling fiber membrane prepared by the preparation method according to any one of claims 1 to 9, characterized in that: The ultra-high reflectivity radiation-cooling fiber film has a reflectivity of greater than 95% in the solar light band of 0.3-2.5μm.
11. The ultra-high reflectivity radiation-cooling fiber membrane according to claim 10, characterized in that: The average pore size of the ultra-high reflectivity radiation-cooling fiber membrane is 0.65±0.23μm, 0.71±0.15μm, or 0.95±0.61μm.
12. The application of the ultra-high reflectivity radiation-cooling fiber membrane according to claim 10 in the fields of clothing, construction or equipment.