Alginate aerogel fiber as well as preparation method and application thereof
By premixing the same solvent as the coagulation bath in the sodium alginate spinning solution, the chemical potential gradient and capillary force were controlled, solving the structural collapse problem of alginate aerogel fibers during room temperature drying. This enabled low-cost, green and environmentally friendly continuous production and high-performance aerogel fiber preparation.
Patent Information
- Application Number
- CN202511558969.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-29
- Publication Date
- 2026-02-13
AI Technical Summary
In the preparation of alginate aerogel fibers, the capillary force during the conventional drying process causes the three-dimensional porous network structure to collapse, making it impossible to maintain the nanoporous structure at room temperature and pressure. Moreover, the existing methods are expensive, complex, and energy-intensive, making it difficult to achieve continuous production.
A solvent premixing strategy is adopted, in which the same solvent as the coagulation bath, such as ethanol, is premixed in the sodium alginate spinning solution. By regulating the chemical potential gradient and capillary force, the driving force of phase separation is reduced, and the mechanism is transformed into nucleation-growth, which ensures the stability and mechanical strength of the porous structure during the drying process.
A three-dimensional nanoporous structure of alginate aerogel fiber was successfully prepared at room temperature and pressure, simplifying the process, reducing costs and energy consumption, and possessing the potential for large-scale continuous production while maintaining the high porosity and mechanical strength of the fiber.
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Figure CN121519205A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of aerogel material preparation, and particularly relates to a sodium alginate aerogel fiber and a preparation method and application thereof. BACKGROUND
[0002] As a new type of material combining the high porosity and high specific surface area characteristics of aerogel materials with the flexibility and weavability of fiber materials, the aerogel fiber exhibits great application potential in the fields of efficient adsorption, thermal insulation, biomedical dressing and tissue engineering scaffold, etc. Sodium alginate, as a natural polymer, has good biocompatibility, degradability and gelation performance, and is an ideal raw material for preparing biomass aerogel fibers.
[0003] At present, the preparation of aerogel materials generally faces the technical bottleneck of the drying process. In the conventional drying process, the huge capillary force generated by the volatilization of the solvent inside the gel will cause the collapse of its fine three-dimensional porous network structure, resulting in the loss of the characteristics of the aerogel. Therefore, the existing technology must rely on special means such as supercritical drying or freeze drying to eliminate the capillary force. However, these methods have inherent defects such as expensive equipment, complex process, high energy consumption, long cycle and difficulty in realizing continuous production, which seriously restricts the large-scale preparation and practical application of aerogel fibers.
[0004] To solve the above problems, the technical personnel in the field have tried to prepare aerogel fibers by combining wet spinning with room temperature drying in order to realize low-cost and continuous production. However, for the sodium alginate system, the gel fiber formed by directly extruding the sodium alginate aqueous solution into a coagulation bath such as ethanol cannot maintain its nano-porous structure in the subsequent room temperature and atmospheric pressure drying process due to the water / ethanol exchange and the strong interfacial tension and capillary force generated during the drying process. Finally, a solid fiber or a fiber membrane with a severely collapsed pore structure is obtained, which cannot obtain a real aerogel fiber. Therefore, how to effectively regulate the phase separation behavior and inhibit the capillary force damage during the wet spinning and room temperature drying process is a key technical problem to be solved for the preparation of sodium alginate aerogel fibers. SUMMARY
[0005] In view of the defect that the wet spinning combined with normal temperature drying cannot prepare alginate aerogel fibers in the prior art, the present application aims to provide an alginate aerogel fiber and a preparation method and application thereof. The present application proposes a "solvent premixing" method to realize the universality mechanism of alginate aerogel fiber drying preparation at normal temperature and pressure. The core lies in the synergistic regulation of the chemical potential gradient of the system and the capillary instability process: by premixing a poor solvent in the sodium alginate spinning solution, the chemical potential difference between the system and the pure coagulation bath is actively reduced, which essentially reduces the total driving force of phase separation, and changes the violent "spinodal decomposition" into a gentle "nucleation-growth" mechanism, thereby guiding the formation of a uniform nanoscale gel network in dynamics. On this basis, the strategy ensures the stability of the porous structure during the drying process through a double path - namely, significantly reducing the surface tension of the pore liquid and strengthening the mechanical strength of the gel skeleton, so that the capillary stress generated during the evaporation process is always suppressed below the yield strength of the network, and finally the three-dimensional nanoporous structure of the alginate aerogel fiber is successfully constructed and maintained at normal temperature and pressure.
[0006] To achieve the above object, the present application adopts the following technical solutions: In a first aspect of the present application, a method for preparing an alginate aerogel fiber by normal temperature drying based on a solvent premixing strategy is provided, characterized in that it comprises the following steps: S1: preparing a spinning solution, which is a homogeneous mixed solution of a sodium alginate aqueous solution and a coagulation bath solvent; S2: extruding the spinning solution obtained in step S1 into a coagulation bath through a wet spinning device to perform phase separation and solidification, and obtaining a nascent fiber; wherein the main component of the coagulation bath is the same as the coagulation bath solvent in the spinning solution; S3: drying the nascent fiber obtained in step S2 at normal temperature and pressure to obtain the alginate aerogel fiber.
[0007] Further, in step S1, the coagulation bath solvent is one or more of ethanol, acetone or isopropyl alcohol, preferably ethanol.
[0008] Further, in step S1, the mass fraction of the coagulation bath solvent in the spinning solution is 4% to 20%. Preferably, the mass fraction is 5% to 10%. Within this range, the ideal pore structure can be effectively regulated by phase separation, and the spinning solution also has suitable spinnability.
[0009] Further, in step S1, the mass concentration of the sodium alginate aqueous solution is 5% to 15%.
[0010] Further, in step S3, the drying is carried out at room temperature (15-35℃) and normal pressure.
[0011] The present application has the following advantages: (1) The "solvent premixing" strategy solves the problem of drying at room temperature: the present application premixes the same solvent as the coagulation bath in the spinning solution, which fundamentally reduces the solvent concentration gradient between the inside and outside of the spinning strip during the gelation process, thereby significantly reducing the interfacial tension during the phase separation process and the influence of capillary force during the subsequent drying process. This is the core and key to realizing the room temperature and pressure drying of alginate aerogel fibers.
[0012] (2) Simple process, low cost, and environmentally friendly: the present application completely abandons expensive and complex supercritical or freeze-drying equipment, and only needs to adjust the spinning solution formula based on the conventional wet spinning process to obtain high-performance aerogel fibers at room temperature and pressure, greatly simplifying the process flow, reducing production cost and energy consumption, and meeting the green manufacturing concept.
[0013] (3) Effective control and maintenance of the structure of aerogel fibers: by adjusting the proportion of the premixed solvent, the phase separation process can be accurately controlled, thereby obtaining alginate aerogel fibers with ideal pore size distribution and high porosity. The fibers prepared by this method successfully avoid the collapse of the pore structure during the drying process.
[0014] (4) Potential for large-scale continuous production: this method is compatible with existing wet spinning equipment and is easy to realize the continuous and large-scale production of alginate aerogel fibers, laying a solid industrialization foundation for the wide application of aerogel fibers. BRIEF DESCRIPTION OF DRAWINGS
[0015] Figure 1 is a scanning electron microscope (SEM) photo of the fiber prepared in Example 1.
[0016] Figure 2 is a SEM photo of the alginate aerogel fiber prepared in Example 2.
[0017] Figure 3 is a SEM photo of the alginate aerogel fiber prepared in Comparative Example 2.
[0018] Figure 4 is a SEM photo of the alginate aerogel fiber prepared in Comparative Example 1. DETAILED DESCRIPTION
[0019] The following examples are used to further illustrate the present application, and the purpose is to illustrate the present application and should not be interpreted as limiting the scope of the present application. The following uses weight parts and weight percentages unless otherwise specified.
[0020] The raw materials used in the present application are all conventional commercially available products unless otherwise specified; the methods used in the present application are all conventional methods in the art unless otherwise specified.
[0021] The embodiments of the present application are further described in the following examples.
[0022] It should be clear that the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.
[0023] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "an" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.
[0024] Example 1 (1) 8 g of sodium alginate was weighed and dissolved in 76 mL of deionized water, and magnetically stirred until completely dissolved to obtain a 8% sodium alginate aqueous solution. Then, 16 g of anhydrous ethanol (i.e. the mass fraction of ethanol in the total spinning solution is 16%) was slowly added to the solution under continuous stirring, and the stirring was continued for 3 hours to obtain a uniform pre-mixed spinning solution.
[0025] (2) The spinning solution was loaded into a syringe pump, and a needle with an inner diameter of 0.26 mm (corresponding to a national standard 25G) was selected to be extruded into a coagulation bath containing anhydrous ethanol. The nascent fiber was obtained by stopping the spinning strip in the coagulation bath for 2 minutes and then guiding it out with a guide roller.
[0026] (3) The nascent fiber was dried at room temperature (25℃) and normal pressure for 24 hours to obtain a sodium alginate aerogel fiber, as shown in Figure 1 The pore size control range is 75-90 nm.
[0027] Example 2 The difference between this embodiment and Example 1 is that in step (1), the mass fraction of anhydrous ethanol in the total spinning solution is 8%. The SEM morphology of the obtained sodium alginate aerogel fiber is shown in Figure 2 The pore size control range is 40-60 nm.
[0028] Example 3 (1) A 5% sodium alginate aqueous solution was prepared. Then, 20% anhydrous ethanol in the total spinning solution was slowly added to the solution under continuous stirring, and the stirring was continued for 3 hours to obtain a uniform pre-mixed spinning solution.
[0029] (2) The spinning solution was loaded into a syringe pump, and a needle with an inner diameter of 0.26 mm (corresponding to national standard 25G) was selected to extrude into a coagulation bath containing absolute ethanol. After the spinning strip stayed in the coagulation bath for 2 minutes for solidification, it was drawn out by a guide roller to obtain the as-spun fiber.
[0030] (3) The as-spun fiber was left to dry at room temperature (25°C) under normal pressure for 24 hours to obtain the alginate aerogel fiber.
[0031] Example 4 (1) A sodium alginate aqueous solution with a mass fraction of 6% was prepared. Then, under continuous stirring, absolute ethanol with a mass ratio of 16% in the total spinning solution was slowly added to the solution, and the stirring was continued for 3 hours to obtain a uniform pre-mixed spinning solution.
[0032] (2) The spinning solution was loaded into a syringe pump, and a needle with an inner diameter of 0.26 mm (corresponding to national standard 25G) was selected to extrude into a coagulation bath containing absolute ethanol. After the spinning strip stayed in the coagulation bath for 2 minutes for solidification, it was drawn out by a guide roller to obtain the as-spun fiber.
[0033] (3) The as-spun fiber was left to dry at room temperature (25°C) under normal pressure for 24 hours to obtain the alginate aerogel fiber.
[0034] Example 5 The difference between this example and Example 1 is that the mass ratio of absolute ethanol in the total spinning solution is 4%.
[0035] Example 6 The difference between this example and Example 1 is that the mass ratio of absolute ethanol in the total spinning solution is 10%.
[0036] Comparative Example 1 The only difference between this comparative example and Example 1 is that the mass ratio of absolute ethanol in the total spinning solution in step (1) is 1%. After drying, the SEM image of the obtained fiber shows that it has a structure with uneven distribution of pores in the fiber. Figure 3
[0037] Comparative Example 2 The only difference between this comparative example and Example 1 is that no ethanol is added in step (1), and the spinning solution is a pure sodium alginate aqueous solution with a mass fraction of 8%. After drying, the SEM image of the obtained fiber shows that it has a dense structure. Figure 4
[0038] The above embodiments illustrate the structure, features and effects of the present application, and the above description is only the preferred embodiments of the present application. Any changes or modifications made according to the concept of the present application, or equivalent embodiments with equivalent changes, are still within the scope of the present application.
[0039] Although the embodiments of the present application are disclosed for illustrative purposes, those skilled in the art can understand that various alternatives, changes and modifications are possible without departing from the spirit and scope of the present application and the appended claims, and therefore the scope of the present application is not limited to the disclosed embodiments.
Claims
1. A process for the preparation of a alginate salt aerogel fiber, characterized in that, Comprising the following steps: S1: preparing a spinning solution, which is a mixture of a sodium alginate aqueous solution and a non-solvent of sodium alginate with a mass ratio of (80-96):(4-20); S2: extruding the spinning solution obtained in step S1 into a coagulation bath through a wet spinning device to perform phase separation and solidification, thereby obtaining a nascent fiber; the coagulation bath is the non-solvent of sodium alginate in step 1; S3: drying the nascent fiber obtained in step S2 at normal temperature and pressure to obtain a sodium alginate aerogel fiber.
2. The method of claim 1, wherein, The non-solvent of sodium alginate is one or more of ethanol, acetone or isopropyl alcohol.
3. The method of claim 1, wherein, The mass concentration of the sodium alginate aqueous solution is 5% to 15%.
4. The method of claim 1, wherein, The coagulation bath is one or more of ethanol, acetone or isopropyl alcohol.
5. A alginate aerogel fiber, characterized in that, Prepared by the method of any one of claims 1 to 4.
6. A tow characterized by, Consisting of the sodium alginate aerogel fiber of claim 5.
7. Use of the sodium alginate aerogel fiber of claim 5 in the preparation of an adsorption material, a thermal insulation material, a biomedical dressing or a tissue engineering scaffold.