A method for preparing a polymeric polysaccharide helical assembly and a method for enhancing and toughening polymeric polysaccharide fibers using the same

Abstract

The application discloses a preparation method of poly-saccharide helical assembly and a poly-saccharide fiber with enhanced toughness prepared by using the same. The specific steps of the poly-saccharide helical assembly include: adding an alcohol solvent to a poly-saccharide aqueous solution, stirring, and separating a solid phase to obtain nanofibers; adding the nanofibers into water to form a dispersion liquid, and performing self-assembly by stirring to obtain the poly-saccharide helical assembly. The poly-saccharide fiber with enhanced toughness contains high-molecular-weight poly-saccharide and the poly-saccharide helical assembly obtained by using the preparation method. The poly-saccharide solution is simply treated by using an alcohol solvent to obtain nanofibers, and the nanofibers can be self-assembled under the action of stirring and shearing to obtain the poly-saccharide helical assembly. The poly-saccharide helical assembly is used in wet spinning combined with a high-molecular-weight poly-saccharide solution to prepare a poly-saccharide fiber, and the mechanical property of the poly-saccharide fiber can be obviously improved.

Description

Technical Field

[0001] This invention belongs to the field of fiber preparation technology, and particularly relates to biopolysaccharide fibers. Specifically, it relates to a method for preparing a polysaccharide helical assembly and a polysaccharide fiber reinforced and toughened using it, as well as the preparation method thereon. Background Technology

[0002] Polysaccharide fibers have attracted much attention from researchers due to their good biocompatibility, degradability, and green manufacturing processes.

[0003] Fiber reinforcement typically enhances tensile strength by adding reinforcing materials or by obtaining highly oriented polymer chains, but toughness is usually significantly sacrificed. Most reported methods either increase mechanical strength at the expense of toughness or improve elongation and toughness at low strength, making the preparation of polysaccharide fibers with high mechanical properties still challenging.

[0004] In nature, strong and tough materials are very common, such as spider silk, wood, and bones. These materials all have multi-scale hierarchical structures. Under stress, the multi-scale hierarchical structure can respond to a wide range of stresses, forming effective stress dissipation and avoiding stress concentration. In other words, it can effectively withstand complex pressures. Therefore, designing multi-scale hierarchical structures can be used as an effective strategy to improve the mechanical properties of fiber materials. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems existing in the prior art and to provide a method for preparing polysaccharide helical assemblies and polysaccharide fibers reinforced and toughened by them, as well as a method for preparing them. The process is simple, the preparation cost is low and it is suitable for large-scale production. At the same time, the polysaccharide fibers obtained have excellent mechanical properties.

[0006] To achieve the above objectives, the present invention provides a method for preparing a polysaccharide helical assembly and a method for preparing polysaccharide fibers that are reinforced and toughened using the assembly, specifically in the following aspects:

[0007] 1. A method for preparing a polysaccharide helical assembly, comprising: (1) adding an alcohol solvent to a polysaccharide aqueous solution, stirring, and separating the solid phase to obtain nanofibers; (2) adding the nanofibers to water to form a dispersion, and self-assembling by stirring to obtain the polysaccharide helical assembly.

[0008] 2. According to the preparation method described in 1 above, wherein in step (1), an alcohol solvent is added to the polysaccharide aqueous solution by dropwise addition; preferably, the volume ratio of the alcohol solvent to the polysaccharide aqueous solution is (0.2-10):1 (e.g., (0.2-2):1), more preferably (0.5-5):1 (e.g., (0.5-1.8):1), and more preferably (0.8-1.5):1.

[0009] 3. According to the preparation method described in 1 above, wherein in step (1):

[0010] The polysaccharide has a weight-average molecular weight of 1–700 kDa (e.g., 5–700 kDa), preferably 15–600 kDa; and / or, the polysaccharide is sodium alginate; and / or, the alcohol solvent is selected from at least one of methanol, ethanol, and isopropanol.

[0011] 4. According to the preparation method described in 1 above, wherein,

[0012] In step (1), the weight concentration of the polysaccharide aqueous solution is 0.1 to 20 wt%, preferably 0.5 to 5 wt%; and / or, in step (2), the concentration of the nanofibers in the dispersion is 0.01 to 5 wt% (e.g., 0.01 to 3 wt%), preferably 0.01 to 3 wt% (e.g., 0.01 to 2 wt%).

[0013] 5. According to the preparation method described in 1 above, wherein in step (2), the stirring speed is 100 r / min or more, preferably 100 to 2000 r / min, and / or the stirring time is 1 h or more, preferably 1 to 20 h.

[0014] 6. The preparation method according to any one of 1 to 5 above, wherein, after the self-assembly, an alcohol reagent is added to the system to precipitate a solid phase, and then optionally dried to obtain the sodium alginate helical assembly; preferably, the alcohol solvent is selected from at least one of methanol, ethanol, and isopropanol.

[0015] 7. A sodium alginate helical assembly obtained by any one of the preparation methods described in 1 to 6 above; preferably, the length of the sodium alginate helical assembly is 300 to 5000 nm and the width is 30 to 800 nm (e.g., 30 to 600 nm).

[0016] 8. A polysaccharide fiber reinforced and toughened by a polysaccharide helical assembly, comprising a high molecular weight polysaccharide and a polysaccharide helical assembly obtained by any one of the preparation methods described in 1 to 6 above; preferably, the weight ratio of the polysaccharide helical assembly to the high molecular weight polysaccharide is (5 to 50):(1 to 10); more preferably, the diameter of the polysaccharide fiber is 5 μm to 500 μm.

[0017] 9. A method for preparing polypolysaccharide fibers reinforced and toughened by polypolysaccharide helical assemblies, preferably used for preparing the polypolysaccharide fibers described in 8 above, the preparation method comprising:

[0018] Step 1: Add the polysaccharide helical assembly obtained by any one of the preparation methods described in 1 to 6 above into a high molecular weight polysaccharide aqueous solution to form a spinning solution;

[0019] Step 2: Spinning is performed using the spinning solution to obtain polysaccharide fibers reinforced and toughened by the polysaccharide helical assembly.

[0020] Preferably, the concentration of the polysaccharide helical assembly in the spinning solution in step 1 is 5-50 wt%.

[0021] Preferably, the concentration of high molecular weight polysaccharide in the spinning solution in step 1 is 1-10 wt%.

[0022] Preferably, the high molecular weight polysaccharide is selected from at least one of chitosan, sodium alginate, carrageenan, xanthan gum, and carboxymethyl cellulose;

[0023] Preferably, the weight-average molecular weight of the high molecular weight polysaccharide is 100-800 kDa, and more preferably 300-700 kDa.

[0024] 10. According to the preparation method described in 9 above, wherein the spinning in step 2 is wet spinning; preferably, the spinning solution is spun into a coagulation bath, the fibers are collected, and optionally air-dried to obtain the polysaccharide fibers; more preferably, the coagulation bath is selected from at least one of calcium chloride aqueous solution, barium chloride, magnesium chloride, and potassium chloride aqueous solution.

[0025] Compared with existing technologies, this invention obtains nanofibers by treating polysaccharide solutions with alcohol solvents. These nanofibers then undergo self-assembly under stirring to form polysaccharide helical assemblies, resulting in a simple preparation method. Using these polysaccharide helical assemblies in polysaccharide fibers prepared by combining wet spinning with high-molecular-weight polysaccharide solutions significantly improves mechanical properties and addresses the problem of low elongation in existing fibers. Attached Figure Description

[0026] Figure 1 An atomic force microscope image of the sodium alginate spiral assembly prepared according to Example 1 of the present invention.

[0027] Figure 2 Scanning electron microscope image of polysaccharide fibers reinforced and toughened by polysaccharide helical assemblies prepared in Example 4 of this invention.

[0028] Figure 3 The graph shows the tensile properties of the polysaccharide fibers reinforced and toughened by the polysaccharide helical assembly prepared in Example 5 of this invention.

[0029] Figure 4 The graph shows the tensile properties of the polypolysaccharide fibers reinforced and toughened by the polypolysaccharide helical assembly prepared in Example 7 of this invention. Detailed Implementation

[0030] One of the objectives of this invention is to provide a method for preparing a polysaccharide helical assembly, comprising: (1) adding an alcohol solvent to a polysaccharide aqueous solution, stirring, and separating the solid phase to obtain nanofibers; (2) adding the nanofibers to water to form a dispersion, and performing self-assembly by stirring to obtain the polysaccharide helical assembly.

[0031] In a preferred embodiment, the alcohol solvent is selected from at least one of methanol, ethanol, and isopropanol.

[0032] In a preferred embodiment, in step (1), an alcohol solvent is added to the polysaccharide aqueous solution by dropwise addition.

[0033] In a further preferred embodiment, in step (1), the volume ratio of the alcohol solvent to the polysaccharide aqueous solution is (0.2-10):1, preferably (0.5-5):1, more preferably (0.8-1.5):1, for example 0.2:1, 0.5:1, 0.8:1, 1.2:1, 1.6:1, 2:1, 3:1, 5:1, 6:1 or 10:1.

[0034] In a preferred embodiment, in step (1), the weight-average molecular weight of the polysaccharide is 1 to 700 kDa, preferably 15 to 600 kDa, for example, 5 kDa, 10 kDa, 20 kDa, 40 kDa, 60 kDa, 80 kDa, 100 kDa, 150 kDa, 200 kDa, 250 kDa, 300 kDa, 350 kDa, 400 kDa, 450 kDa, 500 kDa, 550 kDa, 600 kDa, 650 kDa or 700 kDa.

[0035] In this invention, the polysaccharide can be a polysaccharide with a single molecular weight, or it can be a mixture of two or more polysaccharides with different molecular weights.

[0036] In a preferred embodiment, in step (1), the weight concentration of the polysaccharide aqueous solution is 0.5 to 20 wt%, preferably 0.5 to 10 wt%, for example 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 10 wt%, 15 wt%, or 20 wt%.

[0037] In a preferred embodiment, in step (1), the polysaccharide is sodium alginate.

[0038] In a preferred embodiment, in step (2), the concentration of the nanofibers in the dispersion is 0.01–5 wt%, preferably 0.01–3 wt%, for example 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 4 wt%, or 5 wt%.

[0039] In a preferred embodiment, in step (2), the stirring speed is 100 r / min or more, preferably 100 to 2000 r / min, more preferably 500 to 1200 r / min, for example 100 r / min, 400 r / min, 600 r / min, 800 r / min, 1000 r / min, 1200 r / min, 1400 r / min, 1600 r / min, 1800 r / min or 2000 r / min.

[0040] In a preferred embodiment, in step (2), the stirring time is more than 1 hour, preferably 1 to 20 hours, more preferably 8 to 20 hours, for example 1 hour, 2 hours, 4 hours, 6 hours, 8 hours, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours or 20 hours.

[0041] In a preferred embodiment, an alcohol solvent is optionally added to the system after the self-assembly to precipitate a solid phase.

[0042] In a further preferred embodiment, the sodium alginate helical assembly is optionally dried after the solid phase is precipitated.

[0043] In a further preferred embodiment, the alcohol solvent is selected from at least one of methanol, ethanol, and isopropanol.

[0044] A second objective of this invention is to provide a sodium alginate helical assembly obtained by the preparation method described in one objective of this invention.

[0045] In a preferred embodiment, the length of the sodium alginate spiral assembly is 300–5000 nm and the width is 30–800 nm.

[0046] For example, the length of the sodium alginate helical assembly is 300nm, 500nm, 800nm, 1000nm, 1200nm, 1500nm, 2000nm, 2500nm, 3000nm, 3500nm, 4000nm, 4500nm or 5000nm, and the width is 30nm, 50nm, 80nm, 100nm, 120nm, 150nm, 180nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, 600nm, 700nm or 800nm.

[0047] A third objective of this invention is to provide a polysaccharide fiber reinforced and toughened by a polysaccharide helical assembly, comprising a high molecular weight polysaccharide and a polysaccharide helical assembly obtained by the preparation method described in one objective of this invention.

[0048] In a preferred embodiment, the weight ratio of the polysaccharide helical assembly to the high molecular weight polysaccharide is (5-50):(1-10), for example (5, 10, 15, 20, 25, 30, 35, 40, 45 or 50):(1, 2, 3, 4, 5, 6, 7, 8, 9 or 10); preferably, the content of the polysaccharide helical assembly is higher than the content of the high molecular weight polysaccharide.

[0049] In a further preferred embodiment, the weight ratio of the polysaccharide helical assembly to the high molecular weight polysaccharide is (10-40):(2-6), for example (10, 15, 20, 25, 30, 35 or 40):(2, 3, 4, 5 or 6).

[0050] In a preferred embodiment, the diameter of the polysaccharide fiber is -5μm to 500μm, for example, 5μm, 10μm, 50μm, 100μm, 200μm, 300μm, 400μm, or 500μm.

[0051] The fourth objective of this invention is to provide a method for preparing polysaccharide fibers reinforced and toughened by polysaccharide helical assemblies, preferably used for preparing the polysaccharide fibers described in the third objective of this invention. The preparation method includes:

[0052] Step 1: Add the polysaccharide helical assembly obtained by the preparation method described in one of the objectives of this invention to a high molecular weight polysaccharide aqueous solution to form a spinning solution;

[0053] Step 2: Spinning is performed using the spinning solution to obtain polysaccharide fibers reinforced and toughened by the polysaccharide helical assembly.

[0054] In a preferred embodiment, the concentration of the polysaccharide helical assembly in the spinning solution in step 1 is 5 to 50 wt%, for example, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 30 wt%, 40 wt%, or 50 wt%.

[0055] In a further preferred embodiment, the concentration of the polysaccharide helical assembly in the spinning solution of step 1 is 10-40 wt%, for example, 10 wt%, 12 wt%, 14 wt%, 16 wt%, 18 wt%, 20 wt%, 22 wt%, 24 wt%, 26 wt%, 28 wt%, 32 wt%, 34 wt%, 36 wt%, 38 wt%, or 40 wt%.

[0056] In a further preferred embodiment, the concentration of the polysaccharide helical assembly in the spinning solution of step 1 is 10-25 wt%, for example, 15 wt%-25 wt%.

[0057] In a preferred embodiment, the concentration of high molecular weight polysaccharide in the spinning solution in step 1 is 1 to 10 wt%, for example, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, or 10 wt%.

[0058] In a further preferred embodiment, the concentration of high molecular weight polysaccharide in the spinning solution in step 1 is 2-6 wt%.

[0059] In a preferred embodiment, the high molecular weight polysaccharide is selected from at least one of chitosan, sodium alginate, carrageenan, xanthan gum, and carboxymethyl cellulose.

[0060] In a further preferred embodiment, the weight-average molecular weight of the high molecular weight polysaccharide is 100-800 kDa, preferably 300-600 kDa.

[0061] For example, the weight-average molecular weight of the high molecular weight polysaccharide is 100kDa, 200kDa, 300kDa, 400kDa, 500kDa, 600kDa, 700kDa or 800kDa.

[0062] In a preferred embodiment, the spinning in step 2 is wet spinning.

[0063] In this invention, there is no particular limitation on the wet spinning process; any wet spinning process disclosed in the prior art can be used.

[0064] In a further preferred embodiment, the wet spinning includes: spinning the spinning solution into a coagulation bath, collecting the fibers, and optionally air-drying them to obtain the polysaccharide fibers; preferably, the fibers are collected using rollers.

[0065] In a further preferred embodiment, the coagulation bath is selected from at least one of calcium chloride aqueous solution, barium chloride, magnesium chloride, and potassium chloride aqueous solution.

[0066] Preferably, the concentration of the coagulation bath is 1-20 wt%, more preferably 2-15 wt%, and even more preferably 5-15 wt%, for example, 1 wt%, 2 wt%, 4 wt%, 6 wt%, 8 wt%, 10 wt%, 12 wt%, 14 wt%, 16 wt%, 18 wt%, or 20 wt%.

[0067] The present invention will be further described in detail below through specific embodiments.

[0068] Example 1:

[0069] This embodiment relates to a method for preparing a polysaccharide helical assembly, wherein the polysaccharide helical assembly is a sodium alginate helical assembly, and the specific steps include:

[0070] (a) Sodium alginate powder (35 kDa) was dissolved in deionized water to obtain a 2 wt% sodium alginate aqueous solution. The solution was heated and stirred at 50°C in a water bath for 0.5 h, and then stirred at room temperature to ensure uniform mixing. Ethanol was added dropwise to the sodium alginate aqueous solution and stirred for 2 h. The volume ratio of ethanol to the polysaccharide aqueous solution was 1.2:1. The solid phase was separated by centrifugation to obtain sodium alginate nanofibers.

[0071] (b) The sodium alginate nanofibers were added to water to form a dispersion with a concentration of 0.1 wt%, and stirred at 600 r / min for 10 h to achieve self-assembly of the polysaccharide helical assembly.

[0072] In this embodiment, the obtained sodium alginate spiral assembly was tested using atomic force microscopy, such as... Figure 1 As shown, the sodium alginate helical assembly exhibits a helical structure with a length of 825±150nm and a width of 370±150nm.

[0073] Example 2:

[0074] This embodiment relates to a method for preparing a polysaccharide helical assembly, wherein the polysaccharide helical assembly is a sodium alginate helical assembly, and the specific steps include:

[0075] (a) Sodium alginate powder (35 kDa) was dissolved in deionized water to obtain a 2 wt% sodium alginate aqueous solution. The solution was heated and stirred at 50°C in a water bath for 0.5 h, and then stirred at room temperature to ensure uniform mixing. Ethanol was added dropwise to the sodium alginate aqueous solution and stirred for 2 h. The volume ratio of ethanol to the polysaccharide aqueous solution was 3:1. The solid phase was separated by centrifugation to obtain sodium alginate nanofibers.

[0076] (b) The sodium alginate nanofibers were added to water to form a 2 wt% dispersion, and stirred at 800 r / min for 24 h to allow for self-assembly, resulting in the polysaccharide helical assembly. In this embodiment, the obtained sodium alginate helical assembly was tested using atomic force microscopy. The sodium alginate helical assembly exhibited a helical structure with a length of 910 ± 220 nm and a width of 150 ± 100 nm.

[0077] Example 3:

[0078] This embodiment relates to a method for preparing a polysaccharide helical assembly, wherein the polysaccharide helical assembly is a sodium alginate helical assembly, and the specific steps include:

[0079] (a) Sodium alginate powder (55 kDa) was dissolved in deionized water to obtain a sodium alginate aqueous solution with a concentration of 1.5 wt%. The solution was heated and stirred at 50°C in a water bath for 0.5 h, and then stirred at room temperature to ensure uniform mixing. Isopropanol was added dropwise to the sodium alginate aqueous solution and stirred for 3 h. The volume ratio of isopropanol to the polysaccharide aqueous solution was 5:1. Sodium alginate nanofibers were obtained by centrifugation to separate the solid phase.

[0080] (b) The sodium alginate nanofibers were added to water to form a dispersion with a concentration of 0.5 wt%. The dispersion was stirred at 700 r / min for 11 h to allow for self-assembly, resulting in the polysaccharide helical assembly. In this embodiment, the obtained sodium alginate helical assembly was tested using atomic force microscopy. The sodium alginate helical assembly exhibited a helical structure with a length of 693 ± 170 nm and a width of 350 ± 120 nm.

[0081] Example 4:

[0082] This embodiment relates to a method for preparing polysaccharide fibers reinforced and toughened by polysaccharide helical assemblies, the specific steps of which include:

[0083] (a) The sodium alginate spiral assembly obtained in Example 1 was stirred, added to anhydrous ethanol for precipitation, and dried to obtain the sodium alginate spiral assembly solid phase.

[0084] (b) Prepare a 4wt% sodium alginate (476kDa) aqueous solution, stir for 4h to ensure uniform dispersion, then add the above sodium alginate spiral assembly solid phase, stir evenly to make a spinning solution, the concentration of the sodium alginate spiral assembly solid phase in the spinning solution is 20wt%.

[0085] (c) Prepare a 5 wt% CaCl2 solution as a coagulation bath;

[0086] (d) Polysaccharide fibers are prepared using existing wet spinning technology. The spinning solution from step (b) is spun into a coagulation bath, and the fibers are collected by rollers. The resulting fibers are air-dried at room temperature to obtain polysaccharide fibers reinforced and toughened by polysaccharide helical assemblies.

[0087] In this embodiment, the polysaccharide fibers reinforced and toughened by the polysaccharide helical assemblies prepared above were tested using scanning electron microscopy. Figure 2 As shown, the diameter of the obtained polysaccharide fibers is approximately 100 μm.

[0088] Example 5:

[0089] This embodiment relates to a method for preparing polysaccharide fibers reinforced and toughened by polysaccharide helical assemblies, the specific steps of which include:

[0090] (a) The sodium alginate spiral assembly obtained in Example 1 was stirred, added to anhydrous ethanol for precipitation, and dried to obtain the sodium alginate spiral assembly.

[0091] (b) Prepare a 4wt% sodium alginate (476kDa) aqueous solution, stir for 4h to ensure uniform dispersion, then add the above sodium alginate spiral assembly solid phase, stir evenly to prepare the spinning solution, wherein the concentration of the sodium alginate spiral assembly solid phase in the spinning solution is 22wt%.

[0092] (c) Prepare a 5 wt% CaCl2 solution as a coagulation bath;

[0093] (d) Polysaccharide fibers are prepared using existing wet spinning technology. The spinning solution from step (b) is spun into a coagulation bath, and the fibers are collected by rollers. The resulting fibers are air-dried at room temperature to obtain polysaccharide fibers reinforced and toughened by polysaccharide helical assemblies.

[0094] In this embodiment, the polysaccharide helical assembly reinforced and toughened polysaccharide fibers prepared above were tested using an electronic universal testing machine. Figure 3 As shown, the tensile strength of the obtained polysaccharide fiber is 390 MPa and the tensile strain is 30%.

[0095] Example 6:

[0096] This embodiment relates to a method for preparing polysaccharide fibers reinforced and toughened by polysaccharide helical assemblies, the specific steps of which include:

[0097] (a) The sodium alginate spiral assembly obtained in Example 2 was stirred, added to anhydrous ethanol for precipitation, and dried to obtain the sodium alginate spiral assembly.

[0098] (b) Prepare a 4wt% sodium alginate (335kDa) aqueous solution, stir for 4h to ensure uniform dispersion, then add the above sodium alginate spiral assembly solid phase, stir evenly to make a spinning solution, the concentration of the sodium alginate spiral assembly solid phase in the spinning solution is 10wt%.

[0099] (c) Prepare a 5 wt% CaCl2 solution as a coagulation bath;

[0100] (d) Polysaccharide fibers were prepared using existing wet spinning technology. The spinning solution from step (b) was spun into a coagulation bath, and the fibers were collected using rollers. The resulting fibers were then air-dried at room temperature to obtain polysaccharide fibers reinforced and toughened by polysaccharide helical assemblies. The tensile strength of the obtained polysaccharide fibers was 203.5 MPa, and the tensile strain was 21%.

[0101] Example 7:

[0102] This embodiment relates to a method for preparing polysaccharide fibers reinforced and toughened by polysaccharide helical assemblies, the specific steps of which include:

[0103] (a) The sodium alginate spiral assembly obtained in Example 1 was stirred, added to anhydrous ethanol for precipitation, and dried to obtain the sodium alginate spiral assembly.

[0104] (b) Prepare a 4 wt% carrageenan aqueous solution, then add the above sodium alginate spiral assembly solid phase, stir evenly to make a spinning solution, wherein the concentration of the sodium alginate spiral assembly solid phase in the spinning solution is 8 wt%.

[0105] (c) Prepare a 4 wt% BaCl2 solution as a coagulation bath;

[0106] (d) Polysaccharide fibers are prepared using existing wet spinning technology. The spinning solution from step (b) is spun into a coagulation bath, and the fibers are collected by rollers. The resulting fibers are air-dried at room temperature to obtain polysaccharide fibers reinforced and toughened by polysaccharide helical assemblies.

[0107] In this embodiment, the polysaccharide helical assembly reinforced and toughened polysaccharide fibers prepared above were tested using an electronic universal testing machine. Figure 4 As shown, the tensile strength of the obtained polysaccharide fiber is 155 MPa and the tensile strain is 5.6%.

[0108] Comparative Example 1

[0109] Sodium alginate spirochetes were prepared according to the method in Example 1, except that the sodium alginate nanofiber dispersion was allowed to stand for one week to dissolve without stirring. All other conditions remained the same.

[0110] Atomic force microscopy revealed that no sodium alginate spirochetes were formed.

Claims

1. A method for preparing polysaccharide fibers reinforced and toughened by polysaccharide helical assemblies, the preparation method comprising: Step 1: Add the polysaccharide helical assembly to a high molecular weight polysaccharide aqueous solution to form a spinning solution; the weight-average molecular weight of the high molecular weight polysaccharide is 100~800kDa; Step 2: Spinning is performed using the spinning solution to obtain polysaccharide fibers reinforced and toughened by the polysaccharide helical assembly; The concentration of the polysaccharide helical assembly in the spinning solution in step 1 is 5~50 wt%; the weight ratio of the polysaccharide helical assembly to the high molecular weight polysaccharide is (5~50):(1~10); The preparation method of the polysaccharide helical assembly includes: (1) adding an alcohol solvent to the polysaccharide aqueous solution by dropwise addition, stirring, separating the solid and liquid phases to obtain nanofibers, wherein the polysaccharide is sodium alginate; (2) adding the nanofibers to water to form a dispersion, performing self-assembly by stirring, adding an alcohol solvent to the system after self-assembly to precipitate the solid phase, and then optionally drying to obtain the polysaccharide helical assembly.

2. The preparation method according to claim 1, characterized in that, In step (1), the volume ratio of the alcohol solvent to the polysaccharide aqueous solution is (0.2~10):

1.

3. The preparation method according to claim 1, characterized in that, In step (1), the volume ratio of the alcohol solvent to the polysaccharide aqueous solution is (0.5~5):

1.

4. The preparation method according to claim 1, characterized in that, In step (1): the weight average molecular weight of the polysaccharide is 1~700kDa; and / or the alcohol solvent is selected from at least one of methanol, ethanol, and isopropanol.

5. The preparation method according to claim 1, characterized in that, In step (1): the weight-average molecular weight of the polysaccharide is 15~600kDa.

6. The preparation method according to claim 1, characterized in that, In step (1), the weight concentration of the polysaccharide aqueous solution is 0.1~20wt%; and / or, in step (2), the concentration of the nanofibers in the dispersion is 0.01~5wt%.

7. The preparation method according to claim 1, characterized in that, In step (1), the weight concentration of the polysaccharide aqueous solution is 0.5~10wt%; and / or, in step (2), the concentration of the nanofibers in the dispersion is 0.01~3wt%.

8. The preparation method according to claim 1, characterized in that, In step (2), the stirring speed is 100 r / min or more, and / or the stirring time is 1 h or more.

9. The preparation method according to claim 1, characterized in that, In step (2), the stirring speed is 100~2000 r / min, and / or the stirring time is 1~20 h.

10. The preparation method according to claim 1, characterized in that, The concentration of high molecular weight polysaccharide in the spinning solution in step 1 is 1~10 wt%.

11. The preparation method according to claim 1, characterized in that... The high molecular weight polysaccharide is selected from at least one of chitosan, sodium alginate, carrageenan, xanthan gum, and carboxymethyl cellulose.

12. The preparation method according to claim 1, characterized in that, The weight-average molecular weight of the high molecular weight polysaccharide is 300~600kDa.

13. The preparation method according to any one of claims 1 to 12, characterized in that, The spinning process described in step 2 is wet spinning.

14. The preparation method according to claim 13, characterized in that, The spinning solution is spun into a coagulation bath, the fibers are collected, and optionally air-dried to obtain the polysaccharide fibers.

15. The preparation method according to claim 14, characterized in that, The coagulation bath is selected from at least one of calcium chloride aqueous solution, barium chloride, magnesium chloride, and potassium chloride aqueous solution.

16. A polysaccharide fiber reinforced and toughened by a polysaccharide helical assembly obtained by the preparation method according to any one of claims 1 to 15, wherein the fiber contains a high molecular weight polysaccharide and a polysaccharide helical assembly.

17. The polysaccharide fiber according to claim 16, characterized in that, The length of the sodium alginate helical assembly is 300~5000nm and the width is 30~800nm.

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