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

Abstract

The application discloses a structure-integrated Janus fiber membrane with radiation evaporation and cooling synergy and a preparation method thereof. A PET fiber membrane with good mechanical strength, toughness and other performances is selected as a base fiber membrane, CaHPO4 is loaded on the surface of the PET fiber membrane to modify and enhance the hydrophilic performance, solar reflectivity and infrared thermal emissivity of the PET fiber membrane, octadecyltrichlorosilane is sprayed on the PET fiber membrane loaded with CaHPO4 by using a spraying process, and a uniform and regular arranged reticular hydrophobic coating inner layer and a reticular water transmission channel are deposited on one side, so that the structure-integrated Janus fiber membrane is prepared. The structure-integrated Janus fiber membrane provided by the application not only has the functions of radiation cooling and evaporation cooling synergy and the function of directional water transmission, and the directional water transmission index R is as high as 991%, but also retains the original excellent performance of the PET fiber membrane.

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 hot research topics 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 existing technology, most 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 washability, cuttability, mechanical strength, etc. Therefore, there is a need for an environmentally friendly, simple and large-scale scalable method 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 the fiber membrane prepared by the electrospinning method in the prior art by providing a structurally integrated Janus fiber membrane with radiation evaporation and synergistic cooling and a preparation method thereof. It not only realizes the radiation cooling, synergistic evaporation cooling function and directional moisture transfer function of the Janus fiber membrane, but also the preparation method is 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 synergistic cooling by radiation evaporation. The Janus fiber membrane is prepared using a PET fiber membrane as a substrate and specifically comprises:

[0006] A hydrophilic surface layer, wherein the hydrophilic surface layer is obtained by subjecting the PET fiber membrane to a hydrophilic modification treatment;

[0007] The hydrophobic inner layer is specifically a hydrophobic coating inner layer formed by spraying octadecyltrichlorosilane on one side of the hydrophilically modified PET fiber membrane to form a regularly arranged mesh;

[0008] The mesh water transmission channel is specifically a mesh hydrophilic channel provided on a single side of the Janus fiber membrane forming the hydrophobic inner layer.

[0009] Preferably, the hydrophilic surface layer is CaHPO4 loaded on the surface of the PET fiber membrane.

[0010] The application also provides a preparation method of the radiation-evaporation-coordinated cooling structure-integrated Janus fiber membrane, which specifically comprises the following steps:

[0011] S1, pretreating the PET fiber membrane.

[0012] S2, preparing the hydrophilic surface layer

[0013] The PET fiber membrane pretreated in the S1 step is soaked in a sodium alginate solution for a certain time, and then the PET fiber membrane is sequentially immersed in a CaCl2 solution and a Na2HPO4 solution at a constant temperature, and after being taken out after being immersed in the solutions, the PET fiber membrane is cleaned with deionized water, so as to obtain a PET fiber membrane loaded with CaHPO4.

[0014] S3, preparing the hydrophobic inner layer

[0015] Octadecyltrichlorosilane is dissolved in n-hexane for standby, and the volume ratio of octadecyltrichlorosilane to n-hexane is 1:15-25;

[0016] In the S2 step, the PET fiber membrane loaded with CaHPO4 is covered with a reticular glass fiber as a mask, and a uniform layer of octadecyltrichlorosilane solution is deposited on one side of the CaHPO4@PET fiber membrane by spraying, and after the octadecyltrichlorosilane solution is volatilized and dried, the mask is removed, so as to form a regularly arranged hydrophobic coating inner layer and a reticular water transmission channel.

[0017] Preferably, the pore density of the glass fiber mask in the S3 step is 68%-80%.

[0018] Preferably, the pore density of the glass fiber mask in the S3 step is 74%.

[0019] One or more technical solutions provided in the embodiments of the application have at least the following technical effects or advantages:

[0020] 1. Firstly, a PET fiber film with good mechanical strength, toughness and other properties is selected as a base fiber film, the hydrophilic property, solar reflectivity and infrared thermal emissivity of the PET fiber film are enhanced by loading CaHPO4 on the surface of the PET fiber film, then octadecyltrichlorosilane is sprayed on the PET fiber film loaded with CaHPO4 by a spraying process, a uniform and regular arranged reticular hydrophobic coating inner layer and reticular water transport channel are deposited on one side, that is, the structure integrated Janus fiber film is prepared, the structure integrated Janus fiber film provided by the application not only has the functions of radiative cooling and synergistic evaporative cooling and the function of directional water transport, the directional water transport index R is as high as 991%, and the original excellent performance of the PET fiber film is retained.

[0021] 2. The preparation method provided by the application has simple process, mild reaction conditions, easy post-treatment process, easy control and is suitable for large-scale production.

[0022] 3. By immersing the PET fiber film into a sodium alginate solution, then immersing into a CaCl2 solution and a Na2HPO4 solution in sequence, the PET fiber film loaded with CaHPO4 is obtained, the problem of poor hydrophilic property and low reflectivity of the PET fiber film in the prior art is effectively solved, the hydrophilic property, solar reflectivity and infrared thermal emissivity of the PET fiber film are enhanced, necessary conditions for rapid diffusion and evaporation of water are provided, and a better foundation for subsequent preparation of the Janus fiber film is provided.

[0023] 4. The Janus fiber film provided by the application realizes high solar reflectivity and high mid-infrared emissivity, so that the solar heat absorption can be maximally reduced and the energy of the Janus fiber film can be emitted to outer space through the atmospheric window.

[0024] 5. The interval arrangement of the octadecyltrichlorosilane hydrophobic coating exposes the hydrophilic fiber of the PET fiber film, forms a reticular water transport channel, and can effectively conduct the sweat secreted by the skin. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of the structure integrated Janus fiber film of the application;

[0026] Figure 2 It is a CaHPO4@PET film, PET film and CaHPO4 infrared performance characterization result graph in the application;

[0027] Figure 3 It is an infrared emission performance test result graph of the PET film, CaHPO4@PET film and 74%-Janus fiber film in the application;

[0028] Figure 4Fig. 2 is a chart of the unidirectional transmission index R value test results of the 68%-Janus fiber membrane, the 74%-Janus fiber membrane, the 80%-Janus fiber membrane and the 84%-Janus fiber membrane of the present application;

[0029] Figure 5 Fig. 3 is a chart of the cooling capacity test results of the 68%-Janus fiber membrane, the 74%-Janus fiber membrane, the 80%-Janus fiber membrane and the 84%-Janus fiber membrane of the present application;

[0030] Figure 6 Fig. 4 is a chart of the cooling experiment results of the 74%-OTS@PET Janus fiber membrane obtained by spraying the 74%-Janus and OTS on the original PET fiber membrane to simulate the covering on the human body surface on the heating table at 37°C. DETAILED DESCRIPTION

[0031] The Janus fiber membrane and the preparation method thereof provided by the present application solve the problem of insufficient mechanical strength of the fiber membrane prepared by the electrospinning method in the prior art, realize the radiation cooling and evaporation cooling function and the directional water transmission function of the Janus fiber membrane, and the preparation method is environmentally friendly and simple, and can be expanded in a large area. The mechanical strength of the Janus fiber membrane prepared by taking the PET fiber membrane as a substrate fully meets the requirements.

[0032] The technical solution in the embodiments of the present application is as follows to solve the above problems:

[0033] The washed PET fiber membrane is pretreated by using a sodium alginate solution, and then the PET fiber membrane is sequentially immersed in a CaCl2 solution and a Na2HPO4 solution, and after each immersion and extraction, the PET fiber membrane is cleaned with deionized water 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. Then, octadecyltrichlorosilane is sprayed on the PET fiber membrane loaded with CaHPO4 by using a spraying process to deposit a uniform and regular arranged reticular hydrophobic coating inner layer and a reticular water transmission channel on one side, thereby obtaining the structure integrated Janus fiber membrane. The structure integrated Janus fiber membrane provided by the present application not only has the functions of radiation cooling and evaporation cooling and the function of directional water transmission, but also has a high directional water transmission index R of 991%, and retains the original mechanical strength, toughness and other excellent properties of the PET fiber membrane.

[0034] In order to better understand the above technical solution, the above technical solution will be described in detail below in combination with the drawings in the specification and the specific embodiments. Figures 1-2 Embodiment One ​

[0035] (1) Pretreatment of PET fiber membrane

[0036] Commercial PET fiber membranes were washed with acetone, ethanol and deionized water respectively for 8-12 min under ultrasonic, and the temperature was set to 50-70℃ to remove organic impurities on the surface of the PET fiber membranes, and then dried for standby.

[0037] (2) Preparation of CaHPO4@PET fiber membrane

[0038] ①100 mg of sodium alginate was dissolved in 100 mL of deionized water to obtain a sodium alginate solution, which was used for standby;

[0039] ②The PET fiber membrane prepared in step (1) was immersed in the sodium alginate solution at a constant temperature of 50-70℃ for 20-28 h, and then immersed in a 0.2 mol / L CaCl2 solution at a constant temperature of 50-70℃ for 40 min. After washing with deionized water, it was immersed in a 0.15 mol / L Na2HPO4 solution at a constant temperature of 50-70℃ for 40 min, washed with deionized water, and dried to obtain a CaHPO4@PET fiber membrane.

[0040] (3) Preparation of reticular hydrophobic inner layer

[0041] Octadecyltrichlorosilane (OTS) was dissolved in n-hexane for standby, and the volume ratio of OTS to n-hexane was 1:20.

[0042] A reticular glass fiber mask was covered on the surface of the CaHPO4@PET fiber membrane as a mask, and the pore density of the glass fiber mask was 68%. A uniform OTS layer was deposited on one side of the CaHPO4@PET fiber membrane as a hydrophobic coating layer by spraying. After the OTS solution was dried, the mask was removed to form a reticular water transport channel, and a Janus fiber membrane with integrated structure was prepared. The obtained Janus (68%-Janus) fiber membrane with a hydrophobic coating area of 68%.

[0043] Example Two

[0044] The pore density of the glass fiber mask in Example One was changed to 74%, and other conditions were the same as in Example One to obtain a Janus (74%-Janus) fiber membrane with a hydrophobic coating area of 74%. Example Three

[0045] The pore density of the glass fiber mask in Example One was changed to 80%, and other conditions were the same as in Example One to obtain a Janus (80%-Janus) fiber membrane with a hydrophobic coating area of 80%. Example Four

[0046] The aperture density of the glass fiber mask in Example One was changed to 84%, and other conditions were the same as Example One, to obtain a Janus (84%-Janus) fiber membrane with a hydrophobic coating area of 84%.

[0047] Product infrared performance test of CaHPO4@PET film, PET film and CaHPO4

[0048] Please refer to Figure 2 The product infrared performance of CaHPO4@PET film, PET film and CaHPO4 was tested, and the test range was 250-1500 nm. The results are shown in the CaHPO4@PET infrared spectrum. The symmetric and asymmetric stretching vibration of P=O bond (at 8.25 μm and 8.91 μm), the symmetric stretching vibration of PO4 (at 9.42 μm), and the asymmetric stretching vibration of PO4 (at 10.12 μm) indicate that CaHPO4 is successfully loaded on the PET film.

[0049] Infrared emission performance test of CaHPO4@PET film, PET film and 74%-Janus fiber membrane

[0050] Please refer to Figure 3 The specific steps are as follows: PET film, CaHPO4@PET film and 74%-Janus fiber membrane were tested, and the test range was 0.25-15 μm. The Rsolar (0.25~2.5 μm) and e̅IR (8~13 μm) of PET, CaHPO4@PET and 74%-Janus were calculated.

[0051] 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%.

[0052] The test data results show that the modified PET film with CaHPO4 has high emissivity and reflectivity, and the addition of CaHPO4 improves the emissivity and reflectivity of the PET film.

[0053] One-way transfer index R value test of 68%-Janus fiber membrane, 74%-Janus fiber membrane, 80%-Janus fiber membrane and 84%-Janus fiber membrane

[0054] Please refer to Figure 4The 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%, which shows good one-way water transport capacity. This is because the reticular hydrophilic channel plays a drainage role, which makes the liquid quickly transfer to the hydrophilic layer. This also shows that the existence of the reticular hydrophilic channel is more beneficial to achieve the super-fast one-way transport of water.

[0055] Test of cooling capacity of 68%-Janus fiber membrane, 74%-Janus fiber membrane, 80%-Janus fiber membrane and 84%-Janus fiber membrane

[0056] Please refer to Figure 5 Under the indoor simulation of sunlight, the infrared thermal camera was used to record the real-time temperature of the Janus membrane with different hydrophobic areas.

[0057] The specific operation is that under the stable and continuous sunlight, the fiber membrane is rapidly heated. When the fiber membrane maintains stable fluctuation under the continuous sunlight, 0.1 mL of water is added to the bottom of the fiber membrane. It can be seen that by analyzing the evaporation and drying process of the wet fiber membrane, the drying time of 68%-Janus, 74%-Janus, 80%-Janus and 84%-Janus is 8 min, 7 min, 7.5 min and 8 min respectively. 74%-Janus can quickly transport water to the upper layer, and the drying time is the shortest, which has excellent water evaporation rate.

[0058] The test data results show that CaHPO4 provides good cooling effect generated by radiative cooling, and the fast water transport provided by the reticular hydrophobic inner layer cooperates to realize the efficient moisture and heat management of the Janus fiber membrane, which shows great application potential in functional textiles for personal moisture management.

[0059] Please refer to Figure 6, 74%-Janus and OTS on the original PET fiber membrane by spraying method obtained 74%-OTS@PET Janus fiber membrane at 37 ℃ heating table simulation on the human body surface, the top through the solar simulator AM1.5G under the simulation 1 sun (100 mW / cm2) sunlight, through the thermocouple record the bottom temperature of the fiber membrane, 5 min in the fiber membrane bottom drop 0.1 mL of water. In the instant drop of water fiber membrane temperature decreases rapidly. After 7 min, the temperature of 74%-Janus increases rapidly and reaches the temperature before dropping water, indicating that the water in the fiber membrane is completely volatilized at this time. At this time, 74%-OTS@PET Janus still remains at a lower temperature, until the 16th min, it begins to heat up. After 11 min, the water is completely volatilized.

[0060] The test results prove that the fiber membrane modified by CaHPO4 has faster water transfer and volatilization capacity than the original fiber membrane.

[0061] In summary, the structural integration Janus fiber membrane not only has the function of radiative cooling and evaporative cooling, and the function of directional water transfer. The preparation method of the technical scheme of the application has simple process, mild reaction condition, easy post-treatment process, easy to control, can be applied to large-scale production, and the structural integration Janus fiber membrane prepared by the method solves the common mechanical strength deficiency of the fiber membrane prepared by the electrospinning method in the prior art. The structural integration Janus fiber membrane can meet the requirements of washable, cuttable, mechanical strength and other durability characteristics in actual application, and can be used for the preparation of functional textiles and wearable materials.

[0062] Although preferred embodiments of the application have been described, those skilled in the art will, upon acquiring the basic inventive concept, make additional changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the application.

[0063] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application also intends to include these modifications and variations.

Claims

1. 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 sequence. After the PET fiber membrane is immersed in the solution, it is taken out and washed with deionized water to obtain a PET fiber membrane loaded with CaHPO4; Preparation of S3 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 step S2, the surface of the CaHPO4-loaded PET fiber membrane is covered with a mesh of glass fibers as a mask, and a uniform layer of octadecyltrichlorosilane solution is deposited on one side of the CaHPO4@PET fiber membrane by spraying. After the octadecyltrichlorosilane solution evaporates and dries, the mask is removed, thereby forming a regularly arranged hydrophobic coating inner layer and a mesh of water transmission channels.

2. The preparation method according to claim 1, wherein the pore density of the glass fiber mask in step S3 is 68%-80%.

3. The structurally integrated Janus fiber membrane with radiation evaporation and synergistic cooling is characterized by: The Janus fiber membrane is prepared by the preparation method described in any one of claims 1 to 2.

4. The structurally integrated Janus fiber membrane according to claim 3, wherein the Janus fiber membrane is used to prepare functional textiles or wearable materials.

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