Radiation evaporation synergistic cooling structure integrated Janus fiber membrane and preparation method thereof

Abstract

The invention discloses a radiation evaporation synergetic cooling structure integrated Janus fiber membrane and a preparation method thereof, a PET fiber membrane with good mechanical strength, toughness resistance and other performances is selected as a substrate fiber membrane, CaHPO4 is loaded on the surface of the PET fiber membrane, the PET fiber membrane is modified, the hydrophilic performance, sunlight reflectivity and infrared thermal emissivity of the PET fiber membrane are enhanced, and the radiation evaporation synergetic cooling structure integrated Janus fiber membrane is prepared. And spraying octadecyl trichlorosilane on the PET fiber membrane loaded with CaHPO4 by adopting a spraying process, and depositing a netted hydrophobic coating inner layer and a netted water transmission channel which are uniformly and regularly arranged on a single side, thereby obtaining the structure integrated Janus fiber membrane. The structure-integrated Janus fiber membrane provided by the invention not only has the function of radiation cooling cooperating with evaporation cooling and the function of directional water transmission, the directional water transmission index R is as high as 991%, and the original excellent performance of the PET fiber membrane is reserved.

Description

Technical Field

[0001] The present invention relates to the technical field of fiber membranes, and in particular to a structurally integrated Janus fiber membrane for radiation evaporation and coordinated cooling and a preparation method thereof. Background Art

[0002] With the development of science and technology, functional textiles and wearable materials are becoming a hot research topic to improve human physiological comfort without consuming excess energy to manage the temperature of the entire environment.

[0003] Functional textiles or wearable materials are generally made of fiber membranes. The moisture transfer characteristics of fiber membranes greatly affect the physiological comfort of the human body. The water transfer in traditional fiber membranes is bidirectional, resulting in an undesirable wet and sticky feeling. Therefore, there is an urgent need to develop new fiber membranes with directional water transfer, evaporative cooling and synergistic radiative cooling to achieve more effective moisture management and heat management. In the prior art, most of the fabrics with directional water transfer properties are fiber membranes prepared by electrospinning methods. They generally have the weakness of insufficient mechanical strength and do not meet the durability characteristics required in practical applications, such as wash resistance, cuttability, and mechanical strength. Therefore, a method that is environmentally friendly, simple, and can be expanded over a large area is needed to prepare a strong and durable Janus fiber membrane. Summary of the invention

[0004] The embodiments of the present application solve the problem of insufficient mechanical strength of fiber membranes prepared by electrospinning methods in the prior art by providing a structurally integrated Janus fiber membrane with radiation evaporation and synergistic cooling and a preparation method thereof. Not only does it realize the radiation cooling, synergistic evaporation cooling function and directional moisture transfer function of the Janus fiber membrane, but the preparation method is also environmentally friendly and simple and can be expanded over a large area. The mechanical strength of the Janus fiber membrane prepared with PET fiber membrane as the substrate fully meets the requirements.

[0005] The present application provides a structurally integrated Janus fiber membrane for radiation evaporation and synergistic cooling. The Janus fiber membrane is prepared with a PET fiber membrane as a substrate, and specifically comprises: A hydrophilic surface layer, wherein the hydrophilic surface layer is obtained by subjecting the PET fiber membrane to a hydrophilic modification treatment; The hydrophobic inner layer is specifically a hydrophobic inner layer formed by spraying octadecyltrichlorosilane on one side of the hydrophilically modified PET fiber membrane to form a regularly arranged mesh hydrophobic coating; The mesh water transmission channel is specifically a mesh hydrophilic channel provided on a single side of the Janus fiber membrane forming a hydrophobic inner layer.

[0006] Preferably, the hydrophilic surface layer is CaHPO4 loaded on the surface of the PET fiber membrane.

[0007] The present application also provides a method for preparing a structurally integrated Janus fiber membrane for radiation evaporation and synergistic cooling, which specifically includes the following steps: S1 pre-treats the PET fiber membrane.

[0008] S2 Preparation of hydrophilic surface layer The PET fiber membrane pretreated in step S1 is immersed in a sodium alginate solution for a certain period of time, and then the PET fiber membrane is immersed in a CaCl2 solution and a Na2HPO4 solution at a constant temperature in turn. The PET fiber membrane is taken out from the solution and washed with deionized water to obtain a PET fiber membrane loaded with CaHPO4.

[0009] S3 Preparation of hydrophobic inner layer Dissolve octadecyltrichlorosilane in n-hexane for later use, with the volume ratio of octadecyltrichlorosilane to n-hexane being 1:15-25; In the step S2, the surface of the PET fiber membrane loaded with CaHPO4 is covered with a mesh of glass fibers as a mask, and a uniform layer of octadecyltrichlorosilane is deposited on one side of the CaHPO4@PET fiber membrane by spraying. After the octadecyltrichlorosilane solution evaporates and dries, the mask is removed to form a regularly arranged hydrophobic coating inner layer and a mesh water transmission channel.

[0010] Preferably, the hole density of the glass fiber mask in step S3 is 68% to 80%.

[0011] Preferably, the hole density of the glass fiber mask in step S3 is specifically 74%.

[0012] One or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages: 1. First, a PET fiber membrane with good mechanical strength and toughness resistance is selected as a base fiber membrane. CaHPO4 is loaded on the surface of the PET fiber membrane to modify the PET fiber membrane to enhance its hydrophilicity, solar reflectivity and infrared thermal emissivity. Then, octadecyltrichlorosilane is sprayed on the PET fiber membrane loaded with CaHPO4 by a spraying process, and a layer of uniformly and regularly arranged mesh hydrophobic coating inner layer and a mesh water transmission channel are deposited on one side to obtain a structurally integrated Janus fiber membrane. The structurally integrated Janus fiber membrane provided by the present invention not only has the functions of radiation cooling and synergistic evaporation cooling and directional water transmission, but also has a directional water transmission index R as high as 991%, and retains the original excellent performance of the PET fiber membrane.

[0013] 2. The preparation method provided by the present invention has simple process, mild reaction conditions, easy post-processing process, easy regulation and control, and is suitable for large-scale production.

[0014] 3. By first immersing the PET fiber membrane in a sodium alginate solution, and then immersing it in a CaCl2 solution and a Na2HPO4 solution in sequence, a PET fiber membrane loaded with CaHPO4 is obtained, which effectively solves the problems of poor hydrophilicity and low reflectivity of the PET fiber membrane in the prior art. The hydrophilicity, solar reflectivity and infrared thermal emissivity of the PET fiber membrane are enhanced by modification, which provides the necessary conditions for the rapid diffusion and evaporation of water, and provides a good foundation for the subsequent preparation of Janus fiber membrane.

[0015] 4. The Janus fiber membrane provided by the present invention realizes high solar reflectivity and high and medium infrared emissivity, so that it can minimize solar heat absorption and emit its own energy into outer space through the atmospheric window.

[0016] 5. The interval arrangement of the octadecyltrichlorosilane hydrophobic coating of the present invention exposes the hydrophilic fibers of the PET fiber membrane to the outside, forming a mesh-like water transport channel, which can effectively conduct the sweat secreted by the skin. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the structural integration of the Janus fiber membrane of this application; Figure 2 This is a graph showing the infrared performance characterization results of CaHPO4@PET film, PET film and CaHPO4 in this application; Figure 3 The infrared emission performance test results of PET film, CaHPO4@PET film and 74%-Janus fiber film tested for this application are shown in the figure; Figure 4 This is a graph showing the test results of the one-way transmission index R value of 68%-Janus fiber membrane, 74%-Janus fiber membrane, 80%-Janus fiber membrane and 84%-Janus fiber membrane in this application; Figure 5 This is a graph showing the test results of the cooling capacity of 68%-Janus fiber membrane, 74%-Janus fiber membrane, 80%-Janus fiber membrane and 84%-Janus fiber membrane in this application; Figure 6 This is a graph showing the results of a cooling experiment in which a 74%-OTS@PETJanus fiber membrane obtained by spraying 74%-Janus and OTS on the original PET fiber membrane was simulated by covering the surface of the human body on a heating platform at 37°C. DETAILED DESCRIPTION

[0018] The embodiments of the present application solve the problem of insufficient mechanical strength of fiber membranes prepared by electrospinning methods in the prior art by providing a structurally integrated Janus fiber membrane with radiation evaporation and synergistic cooling and a preparation method thereof. Not only does it realize the radiation cooling, synergistic evaporation cooling function and directional moisture transfer function of the Janus fiber membrane, but the preparation method is also environmentally friendly and simple and can be expanded over a large area. The mechanical strength of the Janus fiber membrane prepared with PET fiber membrane as the substrate fully meets the requirements.

[0019] The technical solution in the embodiment of the present application is to solve the above problems, and the overall idea is as follows: The washed PET fiber membrane is first pretreated with a sodium alginate solution, and then the PET fiber membrane is immersed in a CaCl2 solution and a Na2HPO4 solution in turn, and is washed with deionized water after each immersion and removal, to obtain a CaHPO4@PET fiber membrane. The hydrophilicity, solar reflectivity and infrared thermal emissivity of the PET fiber membrane loaded with CaHPO4 are significantly improved, and then octadecyltrichlorosilane is sprayed on the PET fiber membrane loaded with CaHPO4 by a spraying process, and a layer of uniformly regularly arranged mesh hydrophobic coating inner layer and mesh water transmission channel are deposited on one side, and a structurally integrated Janus fiber membrane is obtained. The structurally integrated Janus fiber membrane provided by the present invention not only has the functions of radiation cooling and synergistic evaporation cooling and directional water transmission, but also has a directional water transmission index R of up to 991%, and retains the original mechanical strength, toughness and other excellent properties of the PET fiber membrane.

[0020] In order to better understand the above technical solution, Figure 1-2 And specific implementation methods are used to describe the above technical solutions in detail. Embodiment 1

[0021] (1) Pretreatment of PET fiber membrane The commercial PET fiber membrane was ultrasonically washed with acetone, ethanol and deionized water for 8-12 min respectively, the temperature was set to 50-70°C to remove organic matter and other impurities on the surface of the PET fiber membrane, and then dried for later use.

[0022] (2) Preparation of CaHPO4@PET fiber membrane ① Dissolve 100 mg of sodium alginate in 100 mL of deionized water to obtain a sodium alginate solution for later use; ② The PET fiber membrane reserved in step (1) is immersed in a sodium alginate solution at a constant temperature of 50-70°C for 20-28 h, and then the PET fiber membrane is immersed in a 0.2 mol / L CaCl2 solution at a constant temperature of 50-70°C for 40 min, washed with deionized water, and then immersed in a 0.15 mol / L Na2HPO4 solution at a constant temperature of 50-70°C for 40 min, washed with deionized water, and dried to obtain a CaHPO4@PET fiber membrane.

[0023] (3) Preparation of the mesh hydrophobic inner layer Dissolve octadecyltrichlorosilane (OTS) in n-hexane for later use, with the volume ratio of OTS to n-hexane being 1:20.

[0024] The surface of the CaHPO4@PET fiber membrane was covered with a mesh of glass fiber as a mask, and the pore density of the glass fiber mask was 68%. A uniform layer of OTS was deposited on one side of the CaHPO4@PET fiber membrane as a hydrophobic coating by spraying. After the OTS solution evaporated and dried, the mask was removed to form a mesh water transmission channel, and a structurally integrated Janus fiber membrane was obtained. The obtained hydrophobic coating area was 68% of the Janus (68%-Janus) fiber membrane.

[0025] Embodiment 2 The hole density of the glass fiber mask in Example 1 was changed to 74%, and other conditions were the same as in Example 1, to obtain a Janus (74%-Janus) fiber membrane with a hydrophobic coating area of ​​74%. Embodiment 3

[0026] The hole density of the glass fiber mask in Example 1 was changed to 80%, and other conditions were the same as in Example 1, to obtain a Janus (80%-Janus) fiber membrane with a hydrophobic coating area of ​​80%. Embodiment 4

[0027] The hole density of the glass fiber mask in Example 1 was changed to 84%, and other conditions were the same as in Example 1, to obtain a Janus (84%-Janus) fiber membrane with a hydrophobic coating area of ​​84%.

[0028] Infrared performance test of CaHPO4@PET film, PET film and CaHPO4 products Please refer to Figure 2The infrared properties of CaHPO4@PET film, PET film and CaHPO4 were tested in the range of 250-1500 nm. The results showed that in the infrared image of CaHPO4@PET, the symmetric and asymmetric stretching vibrations of P=O bond (8.25 μm and 8.91 μm), the symmetric stretching vibration of PO4 (9.42 μm), and the antisymmetric stretching vibration of PO4 (10.12 μm) showed that CaHPO4 was successfully loaded on the PET film.

[0029] Infrared emission performance test of CaHPO4@PET film, PET film and 74%-Janus fiber film Please refer to Figure 3 The specific steps are as follows: PET film, CaHPO4@PET film and 74%-Janus fiber film are tested in the range of 0.25-15 μm. The `Rsolar (0.25~2.5 μm) and e̅IR (8~13μm) of PET, CaHPO4@PET and 74%-Janus are calculated.

[0030] The results show that the `Rsolar of PET is 78.17%, the `Rsolar of CaHPO4@PET increases to 91.10%, and the `Rsolar of P-fabric (74%-Janus) is 92.60%; the e̅IR of PET is 88.24%, the e̅IR of CaHPO4@PET increases to 92.75%, and the e̅IR of P-fabric is 92.77%.

[0031] The test data results show that the CaHPO4-modified PET film has higher emissivity and reflectivity, and the addition of CaHPO4 improves the emissivity and reflectivity of the PET film.

[0032] One-way transmission index R value test of 68%-Janus fiber membrane, 74%-Janus fiber membrane, 80%-Janus fiber membrane and 84%-Janus fiber membrane Please refer to Figure 4 The R values ​​of 68%-Janus, 74%-Janus, 80%-Janus and 84%-Janus are 979%, 991%, 973% and 973% respectively, and the R values ​​are all above 600%, showing good unidirectional water transport capacity. This is because the reticular hydrophilic channels play a drainage role, allowing the liquid to be quickly transferred to the hydrophilic layer. This also shows that the existence of reticular hydrophilic channels is more conducive to achieving ultrafast unidirectional water transport.

[0033] Test on the cooling capacity of 68%-Janus fiber membrane, 74%-Janus fiber membrane, 80%-Janus fiber membrane and 84%-Janus fiber membrane Please refer to Figure 5 , 68%-Janus fiber membrane, 74%-Janus fiber membrane, 80%-Janus fiber membrane and 84%-Janus fiber membrane were placed indoors under simulated sunlight, and an infrared thermal camera was used to record the real-time temperature of the Janus membranes with different hydrophobic areas.

[0034] The specific operation is that the fiber membrane heats up rapidly under stable and continuous sunlight. When the fiber membrane maintains stable fluctuations under continuous sunlight, 0.1 mL of water is added to the bottom of the fiber membrane. It can be seen that the analysis of the evaporation and drying process of the wet fiber membrane shows that the drying times of 68%-Janus, 74%-Janus, 80%-Janus and 84%-Janus are 8 min, 7 min, 7.5 min and 8 min, respectively. 74%-Janus can quickly transfer moisture to the upper layer, has the shortest drying time, and has an excellent water evaporation rate.

[0035] The experimental data results show that CaHPO4 provides a good cooling effect generated by radiation cooling, and cooperates with the rapid water transport provided by the water transport channels of the mesh hydrophobic inner layer to achieve efficient moisture and heat management of the Janus fiber membrane, showing great application potential in functional textiles for personal moisture management.

[0036] Please refer to Figure 6 , the 74%-OTS@PETJanus fiber membrane obtained by spraying 74%-Janus and OTS on the original PET fiber membrane was placed on a heating table at 37 °C to simulate the situation of covering the human body surface. The top was simulated by a solar simulator AM1.5G to simulate 1 sun (100mW / cm2) of sunlight. The bottom temperature of the fiber membrane was recorded by a thermocouple. 0.1 mL of water was dripped on the bottom of the fiber membrane at 5 minutes. The temperature of the fiber membrane dropped rapidly at the moment of dripping water. After 7 minutes, the temperature of 74%-Janus increased rapidly and reached the temperature before dripping water, indicating that the water in the fiber membrane was completely evaporated at this time. At this time, 74%-OTS@PET Janus still maintained a low temperature and did not start to heat up until the 16th minute. It took 11 minutes for the water to completely evaporate.

[0037] The test results prove that the fiber membrane modified with CaHPO4 has faster water transfer and volatilization ability than the original fiber membrane.

[0038] In general, the structurally integrated Janus fiber membrane not only has the functions of radiation cooling, coordinated evaporation cooling and directional moisture transport. The preparation method of the technical solution of the present invention has a simple process, mild reaction conditions, easy post-treatment process, easy regulation, and can be applied to large-scale production. The prepared structurally integrated Janus fiber membrane solves the disadvantage of insufficient mechanical strength that is common in fiber membranes prepared by electrospinning methods in the prior art. The structurally integrated Janus fiber membrane can meet the durability characteristics required in practical applications, such as washing resistance, cuttability, mechanical strength, etc., and can be used for the preparation of functional textiles and wearable materials.

[0039] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0040] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A structurally integrated Janus fiber membrane for radiation evaporation and synergistic cooling, wherein the Janus fiber membrane is prepared using a PET fiber membrane as a base fiber membrane, and specifically comprises: A hydrophilic surface layer, wherein the hydrophilic surface layer is obtained by subjecting the PET fiber membrane to a hydrophilic modification treatment; The hydrophobic inner layer is specifically a hydrophobic inner layer formed by spraying octadecyltrichlorosilane on one side of the hydrophilically modified PET fiber membrane to form a regularly arranged mesh hydrophobic coating; The mesh water transmission channel is specifically a mesh hydrophilic channel provided on a single side of the Janus fiber membrane forming a hydrophobic inner layer.

2. The Janus fiber membrane according to claim 1, characterized in that: The hydrophilic surface layer is CaHPO4 loaded on the surface of the PET fiber membrane.

3. The Janus fiber membrane as described in claim 1 or 2, wherein the area of ​​the octadecyltrichlorosilane coating is 68% to 80%, specifically 74%.

4. A method for preparing a structurally integrated Janus fiber membrane with radiation evaporation and synergistic cooling, characterized in that: The following steps are involved: S1 pre-treats the PET fiber membrane; S2 Preparation of hydrophilic surface layer The PET fiber membrane pretreated in step S1 is immersed in a sodium alginate solution for a certain period of time, and then the PET fiber membrane is immersed in a CaCl2 solution and a Na2HPO4 solution at a constant temperature in turn, and the PET fiber membrane is taken out after being immersed in the solution and washed with deionized water to obtain a PET fiber membrane loaded with CaHPO4; S3 Preparation of hydrophobic inner layer Dissolve octadecyltrichlorosilane in n-hexane for later use, with the volume ratio of octadecyltrichlorosilane to n-hexane being 1:15-25; In the step S2, the surface of the PET fiber membrane loaded with CaHPO4 is covered with a mesh of glass fibers as a mask, and a uniform layer of octadecyltrichlorosilane is deposited on one side of the CaHPO4@PET fiber membrane by spraying. After the octadecyltrichlorosilane solution evaporates and dries, the mask is removed to form a regularly arranged hydrophobic coating inner layer and a mesh water transmission channel.

5. The method according to claim 2, wherein the hole density of the glass fiber mask in step S3 is 68% to 80%.

6. The Janus fiber membrane as claimed in claim 3, wherein the Janus fiber membrane is used in preparing functional textiles or wearable materials.

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