Coaxial fibroin / cellulose aerogel fiber and preparation method thereof

Abstract

The invention discloses a coaxial fibroin / cellulose aerogel fiber and a preparation method thereof. The preparation method comprises the following steps: adding cellulose into a first ion solution to obtain a cellulose solution; adding silk fibroin into the second ion solution to obtain a silk fibroin solution; adding the cellulose solution serving as a core layer spinning solution and the silk fibroin solution serving as a skin layer spinning solution into coaxial wet spinning equipment to extrude and form a coaxial fiber precursor, and performing solidification regeneration, freezing and drying to obtain the coaxial fibroin / cellulose aerogel fiber. According to the preparation method, silk fibroin and cellulose are dissolved in a 1-butyl-3-methylimidazole acetate ionic solution to obtain a spinning solution, the silk fibroin solution serves as a skin layer, the silk fibroin / cellulose aerogel fiber is prepared through coaxial wet spinning in a constant-temperature water bath, the preparation method is simple, large-batch production can be achieved, and the preparation method is suitable for industrial production. No harmful substances are added in the preparation process, no degradation-resistant substances are generated in the product, the product is biodegradable, the recycling rate is high, and the good effect is achieved in the aspect of environmental protection.

Description

Technical Field

[0001] The invention relates to the technical field of aerogel fibers, and in particular to a coaxial silk / cellulose aerogel fiber and a preparation method thereof. Background Art

[0002] Aerogel fibers have shown great potential in the fields of warmth preservation, heat insulation and protection due to their ultra-low density, ultra-high porosity and high specific surface area. However, the unique microstructure of aerogel materials, while giving them many excellent properties, also determines their inherent high brittleness (current aerogel materials are extremely fragile, tensile strength cannot be measured, and relevant data is lacking). They basically exist in the form of particles, powders and rolled felts, which are difficult to meet the requirements of practical applications.

[0003] At present, researchers have been able to improve the mechanical properties of aerogel materials through various methods such as foreign doping and precursor regulation, but there is still a lack of relatively effective methods for the preparation of aerogel fiber materials, and there are very few related reports. Today, most aerogel products on the market are SiO2 aerogels, and their preparation process produces complex chemical reaction waste, which is not easy to degrade, especially not suitable for processing into clothing fabrics that come into direct contact with the human body. However, there is a mature process for using silk, a renewable natural polymer, to process it into silk and other clothing fabrics; the main component of silk is fibroin, and if it is processed into aerogel fibers, it can be used as a weaving fiber for thermal insulation clothing fabrics, and it is also of great significance for the high-value utilization of silk.

[0004] Patent CN106178131A discloses a method for preparing silk fibroin aerogel, but this method directly beats the silk fibroin aqueous solution into a foam and then dries it. If it is not handled in time during this process, especially the high-concentration silk fibroin solution will dry quickly, which is not conducive to actual production. In addition, no effective measures are taken to improve the thermal properties of the aerogel. Therefore, the obtained aerogel fiber is difficult to have ideal thermal insulation and mechanical properties to meet the needs of practical applications.

[0005] In summary, aerogel fibers prepared by traditional methods face problems such as poor thermal insulation and mechanical properties, complex processes and the generation of difficult-to-degrade products. Therefore, it is particularly important to develop a new, efficient and environmentally friendly method to prepare aerogel fiber materials with excellent thermal insulation and mechanical properties. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a coaxial silk / cellulose aerogel fiber and a preparation method thereof, wherein a cellulose solution and a silk protein solution are coaxially wet-spinned to prepare the coaxial silk / cellulose aerogel fiber, wherein the cellulose gel skeleton is wrapped with a silk fiber network, and the fine structure of the multi-scale pore structure sheath and the ultra-low density cellulose aerogel core can synergistically inhibit air circulation and limit convective heat transfer; at the same time, the high porosity of the aerogel fiber weakens heat transfer, and the silk aerogel cell wall can prevent infrared radiation; in addition, the aerogel fiber material prepared by the inventive method does not generate difficult-to-degrade products, is biodegradable, has a high recycling rate, and plays a good role in environmental protection.

[0007] In order to solve the above technical problems, the present invention provides a method for preparing coaxial silk / cellulose aerogel fibers, comprising the following steps: S1, adding cellulose to the first ion solution, mechanically stirring or kneading to obtain a cellulose solution; adding silk fibroin to the second ion solution, mixing and dissolving to obtain a silk fibroin solution; S2, adding the cellulose solution as the core layer spinning solution and the silk fibroin solution as the skin layer spinning solution into a coaxial wet spinning device, and extruding the coaxial fiber precursor in a water bath at room temperature; S3, placing the coaxial fiber precursor in a coagulation bath for coagulation and regeneration to obtain a coaxial silk / cellulose hydrogel; S4, freezing and drying the coaxial silk / cellulose hydrogel to obtain the coaxial silk / cellulose aerogel fiber.

[0008] The present invention dissolves silk fibroin and cellulose in an ion solution to obtain a silk fibroin solution and a cellulose solution, and uses the silk fibroin solution as a cortex spinning solution and the cellulose solution as a core spinning solution, and extrudes coaxial fiber precursors through coaxial wet spinning in a constant temperature water bath, and obtains silk fibroin / cellulose aerogel fibers through coagulation regeneration, freezing and freeze drying. The preparation method is simple and can be mass-produced. No harmful substances are added during the preparation process, and no difficult-to-degrade substances are generated in the product. The product is biodegradable and has a high recycling rate, which plays a good role in environmental protection.

[0009] The aerogel fiber prepared by the method of the present invention consists of a silk fiber network wrapping a cellulose gel skeleton. The fine structure of the multi-scale pore structure sheath and the ultra-low density cellulose aerogel core can synergistically inhibit air circulation and limit convective heat transfer, and has excellent thermal insulation and mechanical properties. At the same time, the high porosity of the aerogel fiber weakens heat transfer, and the silk aerogel cell wall can prevent infrared radiation, further improving the thermal insulation performance.

[0010] Furthermore, in S1, the mass concentrations of the cellulose and the silk fibroin in the cellulose solution and the silk fibroin solution, respectively, are independently selected from 2-5%.

[0011] Further, in S1, the solutes of the first ion solution and the second ion solution are both 1-butyl-3-methylimidazolium acetate, and the mass concentrations of the first ion solution and the second ion solution are independently selected from 20%-50%. The present invention selects 1-butyl-3-methylimidazolium acetate as the solute of the ion solution, which has good solubility in both silk fibroin and cellulose and can achieve uniform blending of the two; it has good stability and is not easy to volatilize, which is conducive to the control of the spinning process; at the same time, it is environmentally friendly and can be recycled and reused, which is in line with the development trend of green chemistry.

[0012] Furthermore, in S4, the freezing temperature is -80°C to -10°C, and the freezing time is 24-48 hours.

[0013] Furthermore, in S4, the drying conditions are: temperature -55°C to -40°C, time 24-48h.

[0014] Furthermore, in S1, the conditions for the mixed dissolution of the silk fibroin are: temperature 20-40° C., rotation speed 400-600 r / min.

[0015] Furthermore, in S2, the extrusion speeds of the core layer spinning solution and the skin layer spinning solution are independently selected from 1-2 ml / min.

[0016] Furthermore, in S3, the coagulation bath is deionized water.

[0017] Furthermore, S3 also includes a washing step, in which the coaxial silk / cellulose hydrogel is washed with deionized water.

[0018] The second aspect of the present invention provides coaxial silk / cellulose aerogel fibers prepared by the method described in the first aspect.

[0019] Furthermore, the coaxial silk / cellulose aerogel fiber has a tensile strength of 10-15 MPa and a specific surface area of ​​500-600 m 2 / g, thermal conductivity is 0.015-0.025W / (m·K).

[0020] Beneficial effects of the present invention: The present invention dissolves silk fibroin and cellulose in an ion solution to obtain a silk fibroin solution and a cellulose solution, and uses the silk fibroin solution as a cortex spinning solution and the cellulose solution as a core spinning solution, and extrudes coaxial fiber precursors through coaxial wet spinning in a constant temperature water bath, and obtains silk fibroin / cellulose aerogel fibers through coagulation regeneration, freezing and freeze drying. The preparation method is simple and can be mass-produced. No harmful substances are added during the preparation process, and no difficult-to-degrade substances are generated in the product. The product is biodegradable and has a high recycling rate, which plays a good role in environmental protection.

[0021] The present invention selects 1-butyl-3-methylimidazolium acetate as the solute of the ion solution, which has good solubility for both silk fibroin and cellulose and can achieve uniform blending of the two; it has good stability and is not easy to volatilize, which is beneficial to the control of the spinning process; at the same time, it is environmentally friendly and can be recycled and reused, which is in line with the development trend of green chemistry.

[0022] The aerogel fiber prepared by the method of the present invention consists of a silk fiber network wrapping a cellulose gel skeleton. The fine structure of the multi-scale pore structure sheath and the ultra-low density cellulose aerogel core can synergistically inhibit air circulation and limit convective heat transfer, and has excellent thermal insulation and mechanical properties. At the same time, the high porosity of the aerogel fiber weakens heat transfer, and the silk aerogel cell wall can prevent infrared radiation, further improving the thermal insulation performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a SEM image of the coaxial silk / cellulose aerogel fiber prepared in Example 1 of the present invention; Figure 2 It is a flow chart of the preparation method of the coaxial silk / cellulose aerogel fiber of the present invention; Explanation of the numbers in the figure: 1. cellulose solution, 2. silk fibroin solution, 3. magnetic stirrer, 4. water bath, 5. coaxial wet spinning equipment, 6. freeze dryer. DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0025] This embodiment provides a method for preparing coaxial silk / cellulose aerogel fibers, referring to Figure 2 As shown, the following steps are included: S1, adding cellulose to a first ionic solution to obtain a cellulose solution 1; adding silk fibroin to a second ionic solution to obtain a silk fibroin solution 2; using a magnetic stirrer 3 to mechanically stir the two solutions and then spinning them as spinning solutions; S2, adding the cellulose solution as the core layer spinning solution and the silk fibroin solution as the skin layer spinning solution into the coaxial wet spinning device 5, placing the device in a water bath 4, and extruding the coaxial fiber precursor in a water bath at room temperature; S3, placing the coaxial fiber precursor in a coagulation bath for coagulation and regeneration to obtain a coaxial silk / cellulose hydrogel; S4, placing the coaxial silk / cellulose hydrogel in a freeze dryer 6 for freezing and drying to obtain the coaxial silk / cellulose aerogel fiber.

[0026] As a specific example, the mass concentrations of cellulose and silk fibroin in the cellulose solution and silk fibroin solution are independently selected from 2-5%; the conditions for the mixed dissolution of silk fibroin are: temperature 20-40°C, rotation speed 400-600r / min; the solutes of the first ion solution and the second ion solution are both 1-butyl-3-methylimidazole acetate, and the mass concentrations of the first ion solution and the second ion solution are independently selected from 20%-50%.

[0027] As a specific example, in S4, the freezing temperature is -80°C to -10°C, and the time is 24-48 hours; the drying conditions are: temperature -55°C to -40°C, and time 24-48 hours.

[0028] As a specific example, in S2, the extrusion speeds of the core layer spinning solution and the skin layer spinning solution are independently selected from 1-2 ml / min.

[0029] As a specific example, in S3, the coagulation bath is deionized water, and a washing step is also included, in which the coaxial silk / cellulose hydrogel is washed with deionized water.

[0030] Another embodiment provides a coaxial silk / cellulose aerogel fiber prepared by the method described in the above embodiment, wherein the coaxial silk / cellulose aerogel fiber has a tensile strength of 10-15 MPa and a specific surface area of ​​500-600 m 2 / g, thermal conductivity is 0.015-0.025W / (m·K).

[0031] The following are specific embodiments. Example 1

[0032] This embodiment relates to a method for preparing a coaxial silk / cellulose aerogel fiber, comprising the following steps: Step (1): Spinning solution preparation Preparation of cellulose solution: 15 g of ionic solution was prepared with 1-butyl-3-methylimidazolium acetate and dimethyl sulfoxide in a mass ratio of 3:7, and 0.45 g of wood pulp cellulose was added. After mechanical stirring, a transparent and uniform cellulose solution with a mass fraction of 3% was obtained after centrifugal degassing. Preparation of silk fibroin solution: prepare an ionic solution with a total mass of 15 g using 1-butyl-3-methylimidazolium acetate and dimethyl sulfoxide in a mass ratio of 3:7, add 0.45 g of silk fibroin, stir and mix at a temperature of 25°C and a speed of 500 r / min, and obtain a transparent and uniform silk fibroin solution with a mass fraction of 3% after centrifugal degassing; Step (2): placing the cellulose solution as the core layer spinning solution and the silk fibroin solution as the skin layer spinning solution into a coaxial wet spinning die at a constant temperature of 25°C in a water bath to extrude and form coaxial fiber precursors, and the extrusion speed of the two spinning solutions is 1.0 ml / min; Step (3): coagulating and regenerating the coaxial fiber precursor after the shaping in a deionized water coagulation bath at 25° C. to form a coaxial fiber hydrogel of a certain shape, and then washing it with deionized water for one day to completely remove the ionic liquid in the coaxial hydrogel to obtain the corresponding coaxial silk / cellulose hydrogel fiber; Step (4): The obtained coaxial silk / cellulose hydrogel fiber is placed in a refrigerator (-10°C) and frozen for 24 hours, and then the cellulose / silk hydrogel is dried by freeze drying technology. The freezing temperature in the freeze drying process is -40°C and the drying time is 48 hours. The coaxial aerogel fiber with synergistic effect and biodegradable properties is obtained. The SEM image is shown in FIG. Figure 1 As shown, it can be seen that the aerogel fiber has an obvious coaxial structure and an obvious skin-core coating structure. Example 2

[0033] This embodiment relates to a method for preparing a coaxial silk / cellulose aerogel fiber, comprising the following steps: Step (1): Spinning solution preparation Preparation of cellulose solution: 15 g of ionic solution was prepared with 1-butyl-3-methylimidazolium acetate and dimethyl sulfoxide in a mass ratio of 3:7, and 0.45 g of wood pulp cellulose was added. After mechanical stirring, a transparent and uniform cellulose solution with a mass fraction of 3% was obtained after centrifugal degassing. Preparation of silk fibroin solution: 15 g of ionic solution was prepared with 1-butyl-3-methylimidazolium acetate and dimethyl sulfoxide in a mass ratio of 3:7, and 0.6 g of silk fibroin was added. The mixture was stirred and mixed at a temperature of 25°C and a speed of 500 r / min. After centrifugal degassing, a transparent and uniform silk fibroin solution with a mass fraction of 4% was obtained. Step (2): placing the cellulose solution as the core layer spinning solution and the silk fibroin solution as the skin layer spinning solution into a coaxial wet spinning die at a constant temperature of 25°C in a water bath to extrude and form coaxial fiber precursors, and the extrusion speed of the two spinning solutions is 1.0 ml / min; Step (3): coagulating and regenerating the coaxial fiber precursor after the shaping in a deionized water coagulation bath at 25° C. to form a coaxial fiber hydrogel of a certain shape, and then washing it with deionized water for one day to completely remove the ionic liquid in the coaxial hydrogel to obtain the corresponding coaxial silk / cellulose hydrogel fiber; Step (4): The obtained coaxial silk / cellulose hydrogel fiber is placed in a refrigerator (-80°C) and frozen for 24 hours, and then the cellulose / silk hydrogel is dried by freeze drying technology. The freezing temperature in the freeze drying process is -40°C and the drying time is 48 hours, thereby obtaining a synergistic and biodegradable coaxial aerogel fiber. Example 3

[0034] This embodiment relates to a method for preparing a coaxial silk / cellulose aerogel fiber, comprising the following steps: Step (1): Spinning solution preparation Preparation of cellulose solution: 15 g of ionic solution was prepared with 1-butyl-3-methylimidazolium acetate and dimethyl sulfoxide in a mass ratio of 3:7, and 0.45 g of wood pulp cellulose was added. After mechanical stirring, a transparent and uniform cellulose solution with a mass fraction of 3% was obtained after centrifugal degassing. Preparation of silk fibroin solution: 15 g of ionic solution was prepared with 1-butyl-3-methylimidazolium acetate and dimethyl sulfoxide in a mass ratio of 3:7, and 0.75 g of silk fibroin was added. The mixture was stirred and mixed at a temperature of 25°C and a speed of 500 r / min. After centrifugal degassing, a transparent and uniform silk fibroin solution with a mass fraction of 5% was obtained. Step (2): placing the cellulose solution as the core layer spinning solution and the silk fibroin solution as the skin layer spinning solution into a coaxial wet spinning die at a constant temperature of 25°C in a water bath to extrude and form coaxial fiber precursors, and the extrusion speed of the two spinning solutions is 1.0 ml / min; Step (3): coagulating and regenerating the coaxial fiber precursor after the shaping in a deionized water coagulation bath at 25° C. to form a coaxial fiber hydrogel of a certain shape, and then washing it with deionized water for one day to completely remove the ionic liquid in the coaxial hydrogel to obtain the corresponding coaxial silk / cellulose hydrogel fiber; Step (4): The obtained coaxial silk / cellulose hydrogel fiber is placed in a refrigerator (-10°C) and frozen for 24 hours, and then the cellulose / silk hydrogel is dried by freeze drying technology. The freezing temperature in the freeze drying process is -40°C and the drying time is 48 hours, thereby obtaining a synergistic and biodegradable coaxial aerogel fiber.

[0035] Comparative Example 1 This comparative example relates to a method for preparing cellulose aerogel fibers, comprising the following steps: Step (1): Spinning solution preparation Preparation of cellulose solution: 15 g of ionic solution was prepared with 1-butyl-3-methylimidazolium acetate and dimethyl sulfoxide in a mass ratio of 3:7, and 0.45 g of wood pulp cellulose was added. After mechanical stirring, a transparent and uniform cellulose solution with a mass fraction of 3% was obtained after centrifugal degassing. Step (2): placing the cellulose solution as the spinning solution into a coaxial wet spinning die in a constant temperature 25°C water bath to extrude and form coaxial fiber precursors, with the extrusion speed being 1.0 ml / min; Step (3): coagulating and regenerating the coaxial fiber precursor after the shaping in a deionized water coagulation bath at 25° C. to form a coaxial fiber hydrogel of a certain shape, and then washing it with deionized water for one day to completely remove the ionic liquid in the coaxial hydrogel to obtain the corresponding coaxial silk / cellulose hydrogel fiber; Step (4): The obtained coaxial silk / cellulose hydrogel fiber is placed in a refrigerator (-10°C) and frozen for 24 hours, and then the cellulose / silk hydrogel is dried by freeze drying technology. The freezing temperature in the freeze drying process is -40°C and the drying time is 48 hours to obtain cellulose aerogel fiber.

[0036] Comparative Example 2 This comparative example relates to a method for preparing a coaxial aerogel fiber, comprising the following steps: Step (1): Spinning solution preparation Preparation of cellulose solution: 15 g of ionic solution was prepared with 1-butyl-3-methylimidazolium acetate and dimethyl sulfoxide in a mass ratio of 3:7, and 0.45 g of wood pulp cellulose was added. After mechanical stirring, a transparent and uniform cellulose solution with a mass fraction of 3% was obtained after centrifugal degassing. Preparation of silk fibroin solution: 15 g of ionic solution was prepared with 1-butyl-3-methylimidazolium acetate and dimethyl sulfoxide in a mass ratio of 3:7, and 0.75 g of silk fibroin was added. The mixture was stirred and mixed at a temperature of 25°C and a speed of 500 r / min. After centrifugal degassing, a transparent and uniform silk fibroin solution with a mass fraction of 5% was obtained. Step (2): placing the cellulose solution as the sheath spinning solution and the silk fibroin solution as the core spinning solution into a coaxial wet spinning die at a constant temperature of 25°C in a water bath to extrude and form coaxial fiber precursors, and the extrusion speed of the two spinning solutions is 1.0 ml / min; Step (3): coagulating and regenerating the coaxial fiber precursor after the shaping in a deionized water coagulation bath at 25° C. to form a coaxial fiber hydrogel of a certain shape, and then washing it with deionized water for one day to completely remove the ionic liquid in the coaxial hydrogel to obtain the corresponding coaxial silk / cellulose hydrogel fiber; Step (4): After the obtained coaxial silk / cellulose hydrogel fiber is placed in a refrigerator (-10°C) and frozen for 24 hours, the cellulose / silk hydrogel is dried by freeze drying technology. The freezing temperature in the freeze drying process is -40°C and the drying time is 48 hours to obtain coaxial aerogel fiber.

[0037] Comparative Example 3 This comparative example relates to a method for preparing a silk fibroin aerogel fiber, comprising the following steps: Step (1): Spinning solution preparation Preparation of silk fibroin solution: prepare an ionic solution with a total mass of 15 g using 1-butyl-3-methylimidazolium acetate and dimethyl sulfoxide in a mass ratio of 3:7, add 0.45 g of silk fibroin, stir and mix at a temperature of 25°C and a speed of 500 r / min, and obtain a transparent and uniform silk fibroin solution with a mass fraction of 3% after centrifugal degassing; Step (2): placing the silk fibroin solution as a spinning solution into a coaxial wet spinning die in a constant temperature 25°C water bath to extrude coaxial fiber precursors, and the extrusion speed of the two spinning solutions is 1.0 ml / min; Step (3): coagulating and regenerating the coaxial fiber precursor after the shaping in a deionized water coagulation bath at 25° C. to form a coaxial fiber hydrogel of a certain shape, and then washing it with deionized water for one day to completely remove the ionic liquid in the coaxial hydrogel to obtain the corresponding coaxial silk / cellulose hydrogel fiber; Step (4): The obtained coaxial silk / cellulose hydrogel fiber is placed in a refrigerator (-10°C) and frozen for 24 hours, and then the cellulose / silk hydrogel is dried by freeze drying technology. The freezing temperature in the freeze drying process is -40°C and the drying time is 48 hours to obtain silk aerogel fiber.

[0038] Comparative Example 4 The difference between this comparative example and Example 1 is that chloride salt is used as the solute of the ion solution, and the other steps remain unchanged.

[0039] Comparative Example 5 The difference between this comparative example and comparative example 5 is that the dissolution temperature of the cellulose solution and the silk solution in step (1) is 50° C., and the other steps remain unchanged.

[0040] Test Case The mechanical properties of the aerogel long fibers prepared in the embodiments and comparative examples were tested; specifically, the tensile strength was tested according to GB / T 14337-2008 using a mechanical properties tester; the specific surface area was tested according to GB / T 16927.1-2008 using a specific surface area tester; the thermal conductivity was tested according to GB / T 10295-2008 using a thermal conductivity meter; the degradability was tested according to GB / T 19277.2-2013 by measuring the amount of carbon dioxide released by the material in an activated sludge environment to evaluate its biodegradability. The test method of the test experiment was performed by a technician in the field according to the relevant debugging standards, and the test results are shown in Table 1.

[0041] Table 1

[0042] As shown in Table 1, the coaxial silk / cellulose aerogel fibers prepared by Examples 1-3 of the present invention have excellent specific surface area and tensile strength, and low thermal conductivity. In the range of 3-5%, the higher the mass concentration of silk, the better the performance. Among them, Example 3 has the best performance, with a specific surface area of ​​596 m 2 / g, the tensile strength reaches 14.0MPa, and the thermal conductivity is as low as 0.019W / (m·K), which overcomes the inherent high brittleness of silk fibroin aerogel materials and has excellent mechanical properties and thermal insulation properties.

[0043] From the comparison between Example 1 and Comparative Example 1 and Comparative Example 3, it can be seen that the coaxial silk / cellulose aerogel fiber has better thermal insulation and mechanical properties than single silk aerogel fiber and cellulose aerogel fiber. From the comparison between Example 3 and Comparative Example 2, it can be seen that the coaxial cellulose / silk aerogel fiber prepared with silk as the sheath and cellulose as the core layer has better mechanical properties and thermal insulation properties, because the mechanical strength of silk is higher than that of cellulose, the mechanical properties of silk as the outer layer material are significantly improved.

[0044] In comparative example 4, chloride salt is used as the solute of the ion solution, and the spinning process is prone to crystallization problems, which affects the smooth spinning process, and the prepared aerogel fiber has poor performance. In comparative example 5, the temperature of the ion solution is increased, and the silk fibroin is decomposed due to the high temperature, which affects the mechanical and thermal insulation properties of the obtained aerogel fiber.

[0045] Cellulose can be degraded by microorganisms and enzymes in the natural environment, gradually decomposed into simple substances such as glucose, and finally mineralized into water and carbon dioxide. Silk can be decomposed into amino acids and other small molecules by microorganisms in the soil. The coaxial silk fibroin / cellulose aerogel fiber prepared by the present invention has excellent degradability, wherein the CO2 release amount in the degradable test of Example 3 reaches 70%, having excellent degradable performance.

[0046] The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or changes made by those skilled in the art based on the present invention are within the protection scope of the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. A method for preparing coaxial silk / cellulose aerogel fibers, characterized in that: The steps include: S1, adding cellulose to the first ion solution, mechanically stirring or kneading to obtain a cellulose solution; adding silk fibroin to the second ion solution, mixing and dissolving to obtain a silk fibroin solution; S2, adding the cellulose solution as the core layer spinning solution and the silk fibroin solution as the skin layer spinning solution into a coaxial wet spinning device, and extruding the coaxial fiber precursor in a water bath at room temperature; S3, placing the coaxial fiber precursor in a coagulation bath for coagulation and regeneration to obtain a coaxial silk / cellulose hydrogel; S4, freezing and drying the coaxial silk / cellulose hydrogel to obtain the coaxial silk / cellulose aerogel fiber.

2. The method for preparing the coaxial silk / cellulose aerogel fiber according to claim 1, characterized in that: In S1, the mass concentrations of the cellulose and silk fibroin are independently selected from 2-5%.

3. The method for preparing the coaxial silk / cellulose aerogel fiber according to claim 1, characterized in that: In S1, the solutes of the first ion solution and the second ion solution are both 1-butyl-3-methylimidazolium acetate, and the mass concentrations of the first ion solution and the second ion solution are independently selected from 20% to 50%.

4. The method for preparing the coaxial silk / cellulose aerogel fiber according to claim 1, characterized in that: In S4, the freezing temperature is -80°C to -10°C, and the freezing time is 24-48 hours.

5. The method for preparing the coaxial silk / cellulose aerogel fiber according to claim 1, characterized in that: In S4, the drying conditions are: temperature -55°C to -40°C, time 24-48h.

6. The method for preparing the coaxial silk / cellulose aerogel fiber according to claim 1, characterized in that: In S1, the conditions for the mixed dissolution of the silk fibroin are: temperature 20-40° C., rotation speed 400-600 r / min.

7. The method for preparing the coaxial silk / cellulose aerogel fiber according to claim 1, characterized in that: In S2, the extrusion speeds of the core layer spinning solution and the skin layer spinning solution are independently selected from 1-2 ml / min.

8. The method for preparing the coaxial silk / cellulose aerogel fiber according to claim 1, characterized in that: In S3, the coagulation bath is deionized water.

9. A coaxial silk / cellulose aerogel fiber prepared by the method according to any one of claims 1 to 8.

10. The coaxial silk / cellulose aerogel fiber according to claim 1, characterized in that: The coaxial silk / cellulose aerogel fiber has a tensile strength of 10-15 MPa and a specific surface area of ​​500-600 m 2 / g, thermal conductivity is 0.015-0.025W / (m·K).

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