Nanometer fibroin fiber membrane with directional water transmission and preparation method thereof

Abstract

The invention discloses a nano fibroin fiber membrane with directional water transport and a preparation method thereof.The preparation method comprises the steps that firstly, renewable pure silk fibroin is extracted from natural silkworm cocoons, a fibroin film with a nanofiber structure is prepared through an electrostatic spinning method, and a methanol treatment method is adopted to induce the fibroin film to generate secondary structure transformation; the hydrophilic moisture absorption characteristic is realized. Octadecyltrichlorosilane (OTS) is sprayed on the fibroin fiber membrane by adopting a spraying process, a netted hydrophobic inner layer and a netted water transmission channel which are uniformly and regularly arranged are deposited on a single side, the prepared fibroin fiber membrane with the OTS coating has a better directional water transmission function, and the directional water transmission index R is as high as 978%. According to the preparation method provided by the invention, the directional water transmission function is realized under the condition of keeping the mechanical property and radiation cooling property of the original fibroin fiber membrane, and the preparation method is environment-friendly and simple and can be expanded on a large scale.

Description

Technical Field

[0001] The invention relates to the technical field of fiber membranes, and in particular to a nano-silk fiber membrane with directional water transmission 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 transport properties of fiber membranes greatly affect the physiological comfort of the human body. The water transport in traditional fiber membranes is bidirectional, resulting in an undesirable wet and sticky feeling. Therefore, it is urgent to develop new fiber membranes with directional water transport to achieve more effective moisture management and heat management. Summary of the invention

[0004] The embodiment of the present application provides a nano-silk fiber membrane with directional water transmission and a preparation method thereof. The silk fiber membrane prepared by electrospinning and subjected to secondary structural treatment has the characteristics of hydrophilic moisture absorption and radiation cooling. Then, a single layer of OTS is sprayed on the silk fiber membrane to form a mesh water transmission channel and a hydrophobic coating, and the function of directional water transmission is achieved while maintaining the mechanical properties of the original silk fiber membrane. The preparation method is environmentally friendly and simple, and can be expanded on a large scale.

[0005] The embodiment of the present application provides a nanosilk fiber membrane with directional water transport, wherein the nanosilk fiber membrane is prepared by electrospinning, and a layer of uniformly and regularly arranged mesh hydrophobic coating is deposited on the surface of the single layer, and a mesh hydrophilic channel is formed on the surface of the single layer.

[0006] Preferably, the mesh hydrophobic coating is octadecyltrichlorosilane, and the coating area is 55% to 65%, specifically 60% of the hydrophobic coating.

[0007] The present application also provides a method for preparing a nanosilk fiber membrane with directional water transport, which specifically comprises the following steps: S1 Preparation of hydrophilic silk fiber membrane First, renewable pure silk protein is extracted from natural silk cocoons, and a silk film with a nanofiber structure is prepared by electrospinning. The secondary structure transformation is induced by methanol treatment to prepare a hydrophilic and hygroscopic silk fiber membrane.

[0008] S2 Preparation of the hydrophobic inner layer Dissolve octadecyltrichlorosilane (OTS) in n-hexane for later use, with the volume ratio of OTS to n-hexane being 1:20.

[0009] The surface of the nanosilk fiber membrane prepared in S1 is covered with a mesh glass fiber as a mask, the pore density of the glass fiber mask is 55%~65%, and a uniform layer of OTS is deposited on one side of the nanosilk fiber membrane as a hydrophobic coating by spraying.

[0010] After the OTS solution evaporates and dries, the mask is removed, and a mesh-like hydrophilic channel is formed on the surface of the nano-silk fiber membrane, thereby preparing a silk fiber membrane with specific directional water transport.

[0011] One or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages: 1. The present invention prepares a silk film with a nanofiber structure by an electrospinning method, and uses a methanol treatment method to induce a secondary structure transformation, so that it can achieve hydrophilic moisture absorption characteristics, radiation cooling characteristics and mechanical strength characteristics. Then, octadecyltrichlorosilane (OTS) is sprayed on the silk fiber membrane by a spraying process, and a layer of uniformly regularly arranged mesh hydrophobic inner layer and mesh water transmission channels are deposited on one side. The obtained silk fiber membrane with OTS coating has the function of directional water transmission, and the directional water transmission index R is as high as 978%, and the radiation cooling characteristics and mechanical strength characteristics of the original silk fiber membrane are retained, which can meet the durability characteristics such as mechanical strength required in practical applications.

[0012] 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.

[0013] 3. A fiber membrane with directional water transport is prepared using a homemade silk fiber membrane as the base membrane. No inorganic particles for improving reflectivity are added to the silk fiber membrane, which is highly safe and comfortable for the human body.

[0014] 4. The spaced arrangement of the octadecyltrichlorosilane hydrophobic coating of the present invention forms a mesh-like water transport channel on the surface of the single-layer silk fiber membrane, which can effectively conduct the sweat secreted by the skin. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the structure of the nanosilk fiber membrane with directional water transport in this application; Figure 2 A schematic diagram of directional water transport of the nanosilk fiber membrane with directional water transport in the present application; Figure 3 This is the spectrum of the nanosilk fiber membrane in the 0.3-15μm band of this application; Figure 4 This is a graph showing the test results of the one-way transmission index R value of 55% silk fiber membrane, 60% silk fiber membrane and 65% silk fiber membrane in this application.

[0016] 1-Nanosilk fiber membrane; 2-Hydrophobic coating; 3-Network hydrophilic channel. DETAILED DESCRIPTION

[0017] The embodiment of the present application provides a nano-silk fiber membrane with directional water transport and a preparation method thereof. The silk fiber membrane prepared by electrospinning and subjected to secondary structural treatment has the characteristics of hydrophilic moisture absorption and radiation cooling. Then, a single layer of OTS is sprayed on the silk fiber membrane to form a mesh water transport channel, and the function of directional water transport is achieved while maintaining the mechanical properties of the original silk fiber membrane. The preparation method is environmentally friendly and simple, and can be expanded on a large scale.

[0018] The technical solution in the embodiment of the present application is to solve the above problems, and the overall idea is as follows: First, pure silk protein, which is renewable, is extracted from natural silk cocoons. A silk film with a nanofiber structure is prepared by electrospinning, and a methanol treatment method is used to induce a secondary structure transformation, so that it can achieve hydrophilic and hygroscopic properties. Octadecyltrichlorosilane (OTS) is then sprayed on the silk fiber membrane by a spraying process, and a uniformly regularly arranged mesh hydrophobic inner layer is deposited on one side. The silk fiber membrane with OTS coating has a relatively good directional water transmission function, and the directional water transmission index R is as high as 978%.

[0019] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods. Embodiment 1

[0020] (1) Preparation of hydrophilic silk fiber membrane ① Preparation of silk 10g of natural silk cocoons are cut into pieces, and the cut pieces are put into a Na2CO3 solution with a concentration of 0.5wt%, and heated to 100°C for degumming treatment, with a bath ratio of 70:1 and a degumming time of 40min~45min; the degummed natural silk is repeatedly washed with distilled water, and dried in an oven at 60°C to obtain degummed silk.

[0021] ②Preparation of pure silk fibroin The degummed silk was dissolved in a formic acid (FA) / CaCl2 solution, wherein the content of CaCl2 was 5wt%, and the degummed silk accounted for 5wt% of the total mixed solution. The mixed solution was then poured into a culture dish and dried to form a film. The obtained film was immersed in distilled water for 2 days, and then dried in an oven at 60°C to obtain pure silk fibroin (SF).

[0022] ③ Preparation of nanosilk fiber membrane The pure silk fibroin in step ② is dissolved in formic acid FA solution to obtain a SF / FA electrospinning solution with a silk fibroin SF content of 15 wt%.

[0023] The electrospinning voltage was 20 kV, the spinning distance was 12 cm, the pushing speed was 2 mL / h, the drum speed was 110 rpm, the ambient temperature was 25 °C, the spinning time was 24 h, and a spinning membrane was made. The spinning membrane was removed and immersed in a methanol solution for 10 min to obtain a nanosilk fiber membrane.

[0024] (2) Preparation of the hydrophobic inner layer Dissolve octadecyltrichlorosilane (OTS) in n-hexane for later use, with the volume ratio of OTS to n-hexane being 1:20.

[0025] The surface of the nano-silk fiber membrane is covered with a mesh of glass fiber as a mask, the pore density of the glass fiber mask is 55%, and a uniform layer of OTS is deposited on one side of the nano-silk fiber membrane 1 by spraying as a hydrophobic coating 2. After the OTS solution evaporates and dries, the mask is removed, and a mesh of hydrophilic channels 3 is formed on the surface of the nano-silk fiber membrane, and a silk fiber membrane with specific directional water transmission is prepared, and the hydrophobic coating area of ​​the obtained silk fiber membrane is 55%.

[0026] Embodiment 2 The hole density of the glass fiber mask in Example 1 was changed to 60%, and other conditions were the same as in Example 1, to obtain a silk fiber membrane with a hydrophobic coating area of ​​60%. Embodiment 3

[0027] The hole density of the glass fiber mask in Example 1 was changed to 65%, and other conditions were the same as in Example 1, to obtain a silk fiber membrane with a hydrophobic coating area of ​​65%.

[0028] Infrared performance test of nanosilk fiber membrane products Please refer to Figure 3 , the spectrum of nanosilk fiber membrane in the 0.3-15μm band, the average reflectivity of sunlight in the 0.3-2.5μm band of nanosilk fiber membrane is 95%, and the average emissivity at the 8-13μm "transparent atmospheric window" is 95%, which has excellent passive cooling characteristics.

[0029] Test of the one-way transmission index R value of 55% silk fiber membrane, 60% silk fiber membrane and 65% silk fiber membrane Please refer to Figure 4The R values ​​of 55% silk fiber membrane, 60% silk fiber membrane and 65% silk fiber membrane are 965%, 978% and 960% 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.

[0030] Experiment on the cooling capacity of 55% silk fiber membrane, 60% silk fiber membrane and 65% silk fiber membrane 55% silk fiber membrane, 60% silk fiber membrane and 65% silk fiber membrane were placed indoors under simulated sunlight, and an infrared thermal camera was used to record the real-time temperature of the silk fiber membranes with different hydrophobic areas.

[0031] 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. The evaporation and drying process of the wet fiber membrane was analyzed and the results were as follows: the drying time of 55% silk fiber membrane, 60% silk fiber membrane and 65% silk fiber membrane was 7.5 min, 6.5 min and 8 min respectively. The 60% silk fiber membrane can quickly transfer water to the upper layer, with the shortest drying time and excellent water evaporation rate. The results are shown in Table 1.

[0032] Table 1 Test results of cooling capacity of 55% silk fiber membrane, 60% silk fiber membrane and 65% silk fiber membrane time 55% silk fiber membrane 60% silk fiber membrane 65% silk fiber membrane 0min 28.2 28.1 28.2 1~3min 35.2 33.1 35.6 3.5min (start adding 0.1 mL of water) 28.9 26.7 29 4~9.5min 29.0 25.8 29.3 9.8min 29.4 26.5 28.3 10min 29.0 32.8 29.0 10.5min 29.3 33.2 28.2 11min 34.8 33.1 29.3 11.5min 34.9 32.6 35 12~14min 35.1 25.5 35.5 The 60% silk fiber membrane and the nanosilk fiber membrane obtained in step ③ were 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 water dripping. After 6.5 minutes, the temperature of the 60% silk fiber membrane increased rapidly and reached the temperature before dripping, indicating that the water in the fiber membrane was completely evaporated at this time. The temperature of the nanosilk fiber membrane began to drop 2 minutes after dripping, and did not start to heat up until the 15th minute. It took 13 minutes for the water to completely evaporate.

[0033] The test results prove that the 60% silk fiber membrane has faster water transfer and volatilization ability than the nano silk fiber membrane obtained in step ③.

[0034] In general, the nano-silk fiber membrane with directional water transport has the functions of radiation cooling and directional water 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 silk fiber membrane with directional water transport can meet the durability characteristics such as mechanical strength required in practical applications, and has good human safety and comfort, and can be used to prepare textiles, especially functional fabrics and wearable materials.

[0035] 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.

[0036] 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 nanosilk fiber membrane with directional water transport, wherein the nanosilk fiber membrane is prepared by electrospinning, and a layer of uniformly and regularly arranged mesh hydrophobic coating is deposited on the surface of the single layer of the nanosilk fiber membrane, and a mesh hydrophilic channel is formed on the surface of the single layer of the nanosilk fiber membrane.

2. The nanosilk fiber membrane according to claim 1, characterized in that The mesh hydrophobic coating is octadecyltrichlorosilane, and the coating area is 55% to 65%.

3. The nanosilk fiber membrane according to claim 2, characterized in that: The mesh hydrophobic coating is octadecyltrichlorosilane, and the coating area is 60%.

4. A method for preparing a nanosilk fiber membrane with directional water transport, comprising the following steps: S1 Preparation of hydrophilic silk fiber membrane First, pure silk protein, which can be recycled, is extracted from natural silk cocoons. A silk film with a nanofiber structure is prepared by electrospinning, and then treated with methanol to induce a secondary structure transformation, thereby preparing a hydrophilic and hygroscopic silk fiber membrane. S2 Preparation of the hydrophobic inner layer Dissolve octadecyltrichlorosilane in n-hexane for later use, with the volume ratio of OTS to n-hexane being 1:20; The surface of the nano-silk fiber membrane prepared in S1 is covered with a mesh of glass fibers as a mask, and a uniform layer of octadecyltrichlorosilane as a hydrophobic coating is deposited on one side of the nano-silk fiber membrane by a spraying method; After the octadecyltrichlorosilane solution evaporates and dries, the mask is removed, and a network of hydrophilic channels is formed on the surface of the nanosilk fiber membrane.

5. The preparation method according to claim 4, wherein the pore density of the glass fiber is 55% to 65%.

6. The nanosilk fiber membrane as described in claim 1, 2 or 3, wherein the nanosilk fiber membrane with directional water transport is used to prepare textiles, especially functional fabrics and wearable textiles.

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