A method for preparing micro-nano fiber

Abstract

The present invention discloses a method for preparing micro-nano fibers with a petal-like nanostructure on the surface. By adding sodium alginate to natural starch, the ratio of linear molecular chains to hyperbranched molecular chains in the spinning solution is changed, the fiber surface structure is regulated, and the "petal"-like nanostructure is formed on the fiber surface. Compared with micro-nano fibers with smooth surfaces, the obtained micro-nano fibers with a "petal"-like nanostructure on the surface can effectively control the adsorption behavior and wetting process due to their large specific surface area. Therefore, in the field of filtration, this fiber has an ultra-high filtration efficiency. At the same time, as a carrier of functional materials, this fiber can provide a sufficiently large surface area, thereby effectively increasing the load and promoting the performance of its functions. In addition, compared with synthetic polymer fibers that are currently widely studied and applied, the fibers with a "petal"-like nanostructure on the surface provided by the present invention have the advantages of a wide source of raw materials and biodegradability.

Description

Technical Field

[0001] The present invention belongs to the technical field of micro-nano fiber material preparation, and specifically relates to a method for regulating the surface morphology of micro-nano fibers. The obtained fibers have great application prospects in the fields of air filtration, tissue engineering, food packaging, etc. Background Art

[0002] Micro-nano materials have special optical, electrical, mechanical, thermal and other properties due to their large specific surface area. These properties can be further improved by introducing smaller pores, protrusions and nanostructures such as whiskers to the surface of the material. For example, the introduction of nanostructures such as pores or whiskers can give the fiber the ability to control the wetting process and adsorption behavior, thereby giving it greater application advantages in the fields of oil-water separation, air filtration and food packaging. For another example, the introduction of nanostructures such as surface pores and through-body pores gives the fiber a larger specific surface area, which can effectively increase the loading capacity of the functional carrier, thereby improving the functional properties of the fiber (such as photocatalysis, antibacterial, drug release and other functions).

[0003] At present, the main methods for introducing nanostructures on the surface of micro-nano fibers include phase separation regulation, hydrothermal growth, and in-situ generation. Among them, although the phase separation method is simple in principle, in order to obtain ideal fibers, the preparation conditions (such as solvent evaporation rate, etc.) must be strictly controlled, and it is affected by the characteristics of the material itself; the principle of the hydrothermal growth method is to introduce secondary structures on the original fiber material. This method is not only affected by the type of material (currently only involves metal oxides), but also has the disadvantages of multiple processes and long processing cycles; in-situ generation is a method of introducing secondary structures on the surface of micro-nano fibers by controlling the growth of crystalline material crystals, and is therefore also limited by the type of material (crystalline metal oxides, etc.) and formation conditions (generally requiring high-temperature calcination). Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing micro-nano fibers. In view of the defects in the prior art, a method for preparing micro-nano fibers with a "petal"-shaped nanostructure is provided by adjusting the components and proportions of the spinning solution.

[0005] In order to solve the above technical problems, the following technical solutions are adopted:

[0006] A method for preparing micro-nano fibers, characterized by comprising the following steps:

[0007] (2) taking a natural starch solution and a sodium alginate solution, mixing them in a certain proportion to obtain a spinning solution;

[0008] (2) The spinning solution obtained in step (1) is subjected to centrifugal spinning to obtain micro-nano fibers with a surface "petal" shape.

[0009] After optimization, in the step (1), the mass ratio of the natural starch solution to the sodium alginate solution is 2:1 to 1:4, and the ratio between the two is based on the solution ratio.

[0010] After optimization, the step (1) of preparing natural starch is as follows: sodium hydroxide is dissolved in distilled water to prepare a sodium hydroxide solution with a mass concentration of 2.0% (w / w), and magnetically stirred at 25° C. for 0.5 h; a solvent is obtained; and natural starch is dissolved in the obtained solvent to obtain a natural starch solution.

[0011] Preferably, the natural starch is natural potato starch and natural cassava starch; wherein the amylopectin content of the natural potato starch is 70%, and the amylopectin content of the natural cassava starch is 80%.

[0012] After optimization, the concentration of the prepared natural starch solution is 10-14%.

[0013] Preferably, the sodium alginate is medical grade sodium alginate, water is used as the solvent, and the solution concentration is 2-4%.

[0014] After optimization, the step (2) of centrifugal spinning is to extrude the jet through a spinneret at high speed, and to form micro-nano fibers with a surface "petal" shape after the solvent evaporates.

[0015] After optimization, the centrifugal spinning in step (2) has a nozzle diameter of 0.51 mm in outer diameter, 0.26 mm in inner diameter, a nozzle length of 12 mm, and a rotation speed of 500-1000 rpm.

[0016] Preferably, during the centrifugal spinning process in step (2), hot air is used to promote the volatilization of the solvent, and the hot air temperature is 35-55°C.

[0017] The above technical solution has the following beneficial effects:

[0018] The present invention provides a simple and effective method for preparing micro-nano fibers with petal-like nanostructures on the surface. By adding sodium alginate to natural starch, the ratio of linear molecular chains to hyperbranched molecular chains in the spinning solution is changed, the fiber surface structure is regulated, and the "petal"-like nanostructure is formed on the fiber surface. Compared with micro-nano fibers with smooth surfaces, the obtained micro-nano fibers with "petal"-like nanostructures on the surface can effectively control the adsorption behavior and wetting process due to their large specific surface area, so in the field of filtration, this fiber has an ultra-high filtration efficiency. At the same time, as a carrier of functional materials, this fiber can provide a sufficiently large surface area, thereby effectively increasing the load and promoting the performance of its functions. In addition, compared with synthetic polymer fibers that are currently widely studied and applied, the fibers with "petal"-like nanostructures on the surface provided by the present invention have the advantages of a wide source of raw materials and biodegradability. It can also be used as a biomaterial and applied in the fields of biological scaffolds, medical dressings, drug release, etc.

[0019] Starch is a natural polymer material composed of hyperbranched molecular chains (amylopectin) and linear molecular chains (amylose), among which the hyperbranched molecular chains are the main component of natural starch (70-80%). In the spinning process, the polymer solution (or melt) is first stretched to form a jet, and at the same time, the polymer macromolecule chains gradually change from the original random coils to the radial orientation of the jet. Therefore, the key to the polymer solution (or melt) to form fibers lies in the effective entanglement of the linear molecular chains after the orientation arrangement, which also makes chemical fiber spinning always require the polymer used for spinning to be a linear molecular chain.

[0020] The present invention starts from the regulation of the ratio of hyperbranched macromolecular chains and linear molecular chains, and by introducing sodium alginate, which is also a carbohydrate but has a linear molecular chain, into natural starch, the regulation of the fiber surface structure has been achieved. The specific principle is: the hyperbranched macromolecular chains cannot form effective entanglement during the jet stretching process, and it is easy to form microstructures along the jet axis when the jet is thinned. After the jet solidifies, these microstructures are also solidified to form surface Wiener structures. When the proportion of linear molecular chains in the solution (or melt) increases, the entanglement ability of the molecular chains in the jet is further improved, which enables the jet to withstand a greater degree of stretching, thereby forming finer fibers. At the same time, the hyperbranched macromolecular chains also undergo a higher degree of disentanglement during the stretching process, thereby forming more Wiener structures on the fiber surface. Therefore, the method provided by the present invention can simply and effectively regulate the fiber surface morphology, thereby being able to broaden its application field. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described below in conjunction with the accompanying drawings:

[0022] Figure 1Scanning electron microscope (SEM) image of the fiber described in Example 1.

[0023] Figure 2 Scanning electron microscope (SEM) image of the fiber described in Example 2.

[0024] Figure 3 Scanning electron microscope (SEM) image of the fiber described in Comparative Example 1.

[0025] Figure 4 Scanning electron microscope (SEM) image of the fiber described in Comparative Example 2. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is described in detail below in conjunction with specific embodiments. In the following embodiments, unless otherwise specified, the reagents, materials and equipment used can be purchased from commercial sources, or prepared by conventional methods, or are commonly used in the industry.

[0027] Example 1

[0028] The method comprises the following steps: dissolving sodium hydroxide in distilled water to prepare a sodium hydroxide solution with a mass concentration of 2.0% (w / w), and subjecting the solution to magnetic stirring at 25° C. for 0.5 h; obtaining a solvent; dissolving natural potato starch (with a branched starch content of 70%) in the prepared solvent to obtain a starch spinning solution with a concentration of 12%; using purified water as a solvent to dissolve sodium alginate to prepare a solution with a concentration of 4%; and subsequently mixing the two solutions at a ratio of natural starch to sodium alginate of 2:1.

[0029] The centrifugal spinning parameters were set as follows: nozzle diameter was 0.51 mm outer diameter, 0.26 mm inner diameter, and nozzle length was 12 mm; the rotation speed was 500 rpm; and the hot air temperature was 55°C.

[0030] Example 2

[0031] The method comprises the following steps: dissolving sodium hydroxide in distilled water to prepare a sodium hydroxide solution with a mass concentration of 2.0% (w / w), and subjecting the solution to magnetic stirring at 25° C. for 0.5 h; obtaining a solvent; dissolving natural cassava starch (with a branched starch content of 80%) in the prepared solvent to obtain a starch spinning solution with a concentration of 14%; using purified water as a solvent to dissolve sodium alginate to prepare a solution with a concentration of 2%; and subsequently mixing the two solutions at a ratio of natural starch to sodium alginate of 1:4.

[0032] The centrifugal spinning parameters were set as follows: nozzle diameter was 0.51 mm outer diameter, 0.26 mm inner diameter, and nozzle length was 12 mm; the rotation speed was 1000 rpm; and the hot air temperature was 35°C.

[0033] Example 3

[0034] The method comprises the following steps: dissolving sodium hydroxide in distilled water to prepare a sodium hydroxide solution with a mass concentration of 2.0% (w / w), and subjecting the solution to magnetic stirring at 25° C. for 0.5 h; obtaining a solvent; dissolving natural potato starch (with a branched starch content of 70%) in the prepared solvent to obtain a starch spinning solution with a concentration of 12%; using purified water as a solvent to dissolve sodium alginate to prepare a solution with a concentration of 3%; and subsequently mixing the two solutions at a ratio of natural starch to sodium alginate of 1:1.

[0035] The centrifugal spinning parameters were set as follows: nozzle diameter was 0.51 mm outer diameter, 0.26 mm inner diameter, and nozzle length was 12 mm; the rotation speed was 750 rpm; and the hot air temperature was 45°C.

[0036] Example 4

[0037] The method comprises the following steps: dissolving sodium hydroxide in distilled water to prepare a sodium hydroxide solution with a mass concentration of 2.0% (w / w), and subjecting the solution to magnetic stirring at 25° C. for 0.5 h; obtaining a solvent; dissolving natural cassava starch (with a branched starch content of 80%) in the prepared solvent to obtain a starch spinning solution with a concentration of 12%; using purified water as a solvent to dissolve sodium alginate to prepare a solution with a concentration of 3%; and subsequently mixing the two solutions at a ratio of natural starch to sodium alginate of 1:1.

[0038] The centrifugal spinning parameter settings are consistent with those in Example 3.

[0039] Comparative Example 1 (the difference from Example 1 is that the spinning solution does not contain sodium alginate solution)

[0040] Referring to Example 1, natural potato starch (branched starch content 70%) was prepared into a starch spinning solution with a concentration of 12%.

[0041] The centrifugal spinning parameter settings were consistent with those in Example 1.

[0042] Comparative Example 2 (the difference from Example 2 is that the spinning solution does not contain natural starch solution)

[0043] Sodium alginate was dissolved in pure water as a solvent to prepare a solution with a concentration of 2%.

[0044] The centrifugal spinning parameter settings are consistent with those in Example 2.

[0045] The above are only specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent replacements or modifications made based on the present invention to solve basically the same technical problems and achieve basically the same technical effects are all included in the protection scope of the present invention.

Claims

1. A method for preparing micro-nano fibers, characterized in that The steps include: (1) taking a natural starch solution and a sodium alginate solution, mixing them in a certain ratio to obtain a spinning solution; the mass ratio of the natural starch solution to the sodium alginate solution is 2:1-1:4, and the ratio between the two is based on the solution ratio; the natural starch is natural potato starch and natural cassava starch; wherein the amylopectin content of the natural potato starch is 70%, and the amylopectin content of the natural cassava starch is 80%; the sodium alginate is medical grade sodium alginate, and water is used as a solvent, and the solution concentration is 2-4%; Preparation of natural starch: dissolving sodium hydroxide in distilled water to prepare a sodium hydroxide solution with a mass concentration of 2.0% (w / w), and stirring the solution under magnetic force for 0.5h at 25°C; obtaining a solvent; dissolving natural starch in the obtained solvent to obtain a natural starch solution, wherein the concentration of the obtained natural starch solution is 10-14%; (2) The spinning solution obtained in step (1) is subjected to centrifugal spinning to obtain micro-nano fibers with a "petal"-shaped surface.

2. The method for preparing micro-nano fibers according to claim 1, characterized in that: The step (2) of centrifugal spinning is to extrude the jet through a spinneret at high speed, and form micro-nano fibers with a surface shape of "petals" after the solvent evaporates.

3. The method for preparing micro-nano fibers according to claim 1, characterized in that: In the step (2) centrifugal spinning, the nozzle diameter is 0.51 mm in outer diameter, 0.26 mm in inner diameter, 12 mm in nozzle length, and the rotation speed is 500-1000 rpm.

4. The method for preparing micro-nano fibers according to claim 1, characterized in that: In the centrifugal spinning process of step (2), hot air is used to promote the volatilization of the solvent, and the hot air temperature is 35-55°C.

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