A method for preparing surface-modified chitin whiskers

Abstract

This invention discloses a method for preparing surface-modified chitin whiskers. The method includes the following steps: taking an appropriate amount of chitin for acid hydrolysis; after the reaction, removing the supernatant by centrifugation and washing; then adding the acid-hydrolyzed chitin to purified water; adding sodium hydroxide or potassium hydroxide and chloroacetic acid in proportion; setting the reaction conditions; after the reaction is complete, diluting and allowing it to stand; washing the remaining solid by centrifugation; dialyzing with water; and then performing ultrasonic and freeze-drying steps. This invention, while retaining the key structure of chitin whiskers, simply and efficiently prepares surface-modified chitin whiskers with superior dispersibility and compatibility compared to regular chitin whiskers. Simultaneously, the combined centrifugation-dialysis purification technology significantly shortens the reaction cycle and reduces production costs, greatly enhancing the application prospects of chitin whiskers in cosmetics, daily chemicals, and pharmaceuticals.

Description

Technical Field

[0001] This invention belongs to the field of biomaterials technology, specifically a method for preparing surface-modified chitin whiskers. Background Technology

[0002] Chitin, also known as chitosan, is abundant in nature and widely found in crustaceans. It possesses excellent biocompatibility and biodegradability, making it a biosafe material. However, chitin is poorly soluble in water and most organic solvents, significantly limiting its development and application. Chitin whiskers (CW) are a type of chitin fiber obtained by removing the amorphous portion of chitin, retaining the highly ordered crystalline structure. This process preserves chitin's excellent biological characteristics and improves its purity, achieving nanoscale microstructures. While chitin whiskers are as poorly soluble as chitin itself, they can form uniformly dispersed suspensions in water or water-oil systems, making them easier to process. Furthermore, the ordered atomic arrangement of chitin whiskers results in high strength and high modulus. Chitin whiskers are mainly prepared by acid hydrolysis. Acid hydrolysis removes the amorphous and disordered crystalline structure regions of chitin, while the highly crystalline regions remain intact. The method includes acid hydrolysis, washing, dialysis, and ultrasonic or homogenization treatment. During the preparation process, the electrostatic repulsion caused by the protonation of amines in chitin, combined with ultrasonic or homogenization treatment, will form positively charged chitin whiskers.

[0003] Chitin whiskers, as an important chitin derivative, are widely used in various composite materials such as hydrogels, microspheres, and tissue engineering scaffolds. With their nanoscale size and high modulus, they are a high-performance filler that can improve the mechanical properties and shape stability of the matrix, and are applied in cosmetics, pharmaceuticals, food, engineering materials, and other fields. However, if the concentration of chitin whiskers in aqueous solution is high, or when mixed with other components, the dispersed whiskers are still easily precipitated or deposited, which limits the further application of chitin whiskers.

[0004] Currently, research on chitin whiskers often involves mixing them with other polymer materials to form solids such as gels, microspheres, and scaffolds. For example, patent number "CN 117304551A" entitled "A method for preparing PBAT microfoamed composite material reinforced and toughened with modified chitin whiskers" uses chitin whiskers as an additive to enhance the strength and toughness of PBAT-based composite materials. However, there is very little research on the structural properties of chitin whiskers as the main component. Other research involves the modification of chitin whiskers, such as patent number "CN 106868631A" entitled "A chitin nanowhiskers, chitin nanofibers and their preparation method," which prepares whiskers with different aspect ratios, focusing on improving the length and width of the whiskers. These methods are complex and lengthy, and significantly alter the structural properties of the chitin whiskers themselves. This invention is based on the conventional chitin whisker preparation method and optimizes the traditional method. It also introduces a surface-modified chitin whisker method, which solves the problems of long cycle, poor compatibility and stability of existing methods. This method is simple and efficient, which is conducive to supporting the further in-depth application and industrial production of chitin whiskers in various fields. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an improvement, offering a method for preparing surface-modified chitin whiskers. Based on the characteristic structure of chitin whiskers, this invention optimizes conventional preparation and purification methods while maintaining their fundamental microstructure. It utilizes a one-step surface modification method, which is simpler, has a shorter cycle time, and higher production efficiency compared to other modification methods. Furthermore, it significantly improves the compatibility of chitin whiskers in solution systems, enhancing their application value in daily chemicals, pharmaceuticals, and cosmetics. This invention is achieved through the following technical solution:

[0006] This invention discloses a method for preparing surface-modified chitin whiskers, specifically including the following steps:

[0007] Step 1: Preparation of chitin by acid hydrolysis: Chitin powder is mixed with acid solution and heated and stirred to allow it to react fully. After the reaction stops, purified water is added and the supernatant is removed by high-speed centrifugation. The supernatant is then washed 1-5 times by centrifugation. The remaining solid is acid hydrolyzed chitin.

[0008] Step 2, Carboxymethylation modification: Add acid-hydrolyzed chitin to purified water, the reaction temperature is 40℃-65℃, the mass ratio of chitin to chloroacetic acid is 1:0.3-0.6, then add sodium hydroxide or potassium hydroxide to prepare a specific alkaline carboxylation reaction solution, and stir the reaction.

[0009] Step 3: After the reaction in Step 2 is completed, add purified water and remove the supernatant by high-speed centrifugation. Then, repeat the washing process by centrifugation 1-5 times to obtain the washed solid.

[0010] Step 4: Add purified water to the solid obtained in Step 3 and dialyze it. After dialyzing, sonicate it. The final aqueous solution is the dispersion of surface-modified chitin whiskers. Freeze-dry it to obtain a sponge-like sample of surface-modified chitin whiskers.

[0011] As a further improvement, in step one of the present invention, the amount of purified water added is 1-5 times the total volume of the mixed solution, the high-speed centrifugation speed is 3000r / min-10000r / min, and the centrifugation time is 20min-60min. The repeated washing method is as follows: add purified water and centrifuge at high speed to remove the supernatant, with the centrifugation parameters as above.

[0012] As a further improvement, in step one of the present invention, the acid solution is a sulfuric acid solution, the mass ratio of chitosan powder to sulfuric acid solute is 1:8-10, and the specific reaction conditions of chitosan powder and sulfuric acid solution are: reaction temperature of 70℃-90℃ and reaction time of 9h-18h.

[0013] As a further improvement, in step two of this invention, the pH of the alkaline carboxylation reaction solution is adjusted to 12-13 using sodium hydroxide or potassium hydroxide, and the reaction time is 1-4 hours.

[0014] As a further improvement, in step three of this invention, the amount of purified water added is 1-5 times the total volume of the mixed solution, the high-speed centrifugation speed is 3000r / min-10000r / min, and the centrifugation time is 20min-60min. The repeated washing method is as follows: add purified water and centrifuge at high speed to remove the supernatant, with the centrifugation parameters as above.

[0015] As a further improvement, in step four of this invention, the total dialysis time is 1-2 days, with a water change interval of 2-4 hours. The ultrasonic parameters for the dialysis solution are 150W-600W for 5-30 minutes. The final aqueous solution is the dispersion of surface-modified chitin whiskers. The dispersion is then freeze-dried for 24-48 hours to obtain a sponge-like sample of surface-modified chitin whiskers.

[0016] This invention, while retaining the key structure of chitin whiskers, provides a simple and efficient preparation of surface-modified chitin whiskers with superior dispersibility and compatibility compared to regular chitin whiskers. Furthermore, the combination of centrifugation-dialysis purification technology significantly reduces reaction time and production costs, greatly enhancing the application prospects of chitin whiskers in cosmetics, daily chemicals, and pharmaceuticals.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. This invention preferably optimizes the preparation method based on a typical acidolysis reaction. The acid solution is a sulfuric acid solution, and the mass ratio of chitosan powder to sulfuric acid solute is 1:8-10. The specific reaction conditions for chitosan powder and the sulfuric acid solution are: a reaction temperature of 70℃-90℃ and a reaction time of 9h-18h. Furthermore, the supernatant is removed by high-speed centrifugation at a speed of 3000r / min-10000r / min for 20min-60min. The washing process is then repeated 1-5 times using centrifugation. Centrifugation effectively removes impurities and reaction byproducts, replacing the long settling step in conventional methods and shortening the production cycle.

[0019] 2. Based on the optimized method of this invention, the acid-hydrolyzed chitin obtained after centrifugation was directly modified with surface carboxymethylation. The resulting reactants were centrifuged at high speed (3000-10000 rpm) for 20-60 minutes to remove the supernatant. The centrifugation process was repeated 1-5 times. After dialysis for 1-2 days, the solution was sonicated at 150-600 W for 5-30 minutes. Following sonication, the solution was freeze-dried for 24-48 hours to obtain a sponge-like sample with surface-modified chitin whiskers. This method omits the conventional settling step, significantly shortens the dialysis and freeze-drying reaction cycle, and improves reaction efficiency.

[0020] 3. The preparation of conventional chitin whiskers generally takes more than 10 days, and the preparation of different modified whiskers generally takes more than 7 days. However, the preparation of surface-modified chitin whiskers from chitin raw materials using the method described in this invention only takes about 7 days, saving more than 50% of the time. This greatly simplifies the reaction cycle and process, significantly improves production efficiency, and reduces production costs.

[0021] 4. This invention avoids the significant damage to the molecular structure of chitin whiskers caused by chemical reactions. During carboxymethylation modification, the reaction temperature is selected as 40℃-65℃, the solution pH is 12-13, the mass ratio of chitin to chloroacetic acid is 1:0.3-0.6, and the reaction time is 1h-4h. These mild reaction conditions allow the surface-modified chitin whiskers to retain their key structural features, thus preserving various properties such as nanoscale size and high crystallinity. It can serve as a substitute filler for chitin whiskers to improve the mechanical properties and shape stability of the matrix.

[0022] 5. The characteristic properties of chitin whiskers, namely their dispersion properties, are greatly optimized by this method. The surface-modified whiskers prepared by this invention have superior dispersion properties compared to chitin whiskers. Under the same ultrasonic conditions, the ultrasonic time is reduced from 30 minutes to 5-10 minutes, increasing the dispersion efficiency by at least 200%. At the same time, it reduces wear and tear on the equipment and facilitates continuous operation of the equipment. Furthermore, the dispersed whiskers can maintain stability for a longer period of time.

[0023] 6. The surface-modified chitosan whiskers prepared by this invention exhibit better compatibility with various commonly used active ingredients in solution systems and can remain stable in solution for more than 14 days, such as carboxymethyl chitosan, polyethylene glycol, and nicotinamide. Unmodified chitosan whiskers often experience sedimentation, precipitation, and exudation on the same day, greatly enhancing the application prospects of chitosan whiskers in cosmetics, daily chemicals, and pharmaceuticals. Attached Figure Description

[0024] Figure 1 This is a flowchart of the method of the present invention;

[0025] Figure 2 Infrared spectrum of surface-modified chitin whiskers prepared according to the present invention;

[0026] Figure 3 Viscoelasticity diagram of the surface-modified chitin whisker-reinforced temperature-sensitive chitin gel prepared in this invention;

[0027] Figure 4 Microscopic morphology diagram of the surface-modified chitin whiskers prepared in this invention;

[0028] Figure 5 Crystallinity curve of surface-modified chitin whiskers prepared according to the present invention;

[0029] Figure 6 The nanoparticle size distribution diagram of the surface-modified chitin whiskers prepared in this invention;

[0030] Figure 7 Dispersion state diagram of surface-modified chitin whiskers prepared for this invention after ultrasonic treatment;

[0031] Figure 8 This is a diagram showing the state of the surface-modified chitin whiskers prepared according to the present invention mixed with the active ingredients. Detailed Implementation

[0032] This invention is based on the conventional acid hydrolysis method for preparing chitin whiskers, with extensive method optimization and surface carboxymethylation modification of the chitin whiskers. During the reaction process, high-speed centrifugation is rationally applied to the preparation of chitin whiskers and surface-modified chitin whiskers, achieving separation and purification, significantly shortening the cycle of dialysis and freeze-drying steps, thereby improving overall production efficiency and reducing production costs.

[0033] The modification method of this invention can be directly carried out on the basis of acid hydrolysis of chitin, simplifying the modification method and selecting a milder reaction step. It only requires adding materials in an appropriate proportion in an aqueous solution at medium and low temperature for a short reaction time to obtain chitin whiskers with surface carboxymethylation modification. This surface-modified chitin whisker basically retains the key structure of chitin whiskers, namely nanoscale size and high crystallinity, and can be used as a substitute filler for chitin whiskers to improve the mechanical properties and shape stability of the matrix. Moreover, it also has better dispersion performance and compatibility than chitin whiskers.

[0034] To further understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1:

[0036] Preparation of surface-modified chitin whiskers: Weigh 0.5g of chitin powder and add 15ml of 3mol / L sulfuric acid solution at 90℃ for acid hydrolysis. After 9h of reaction, wash the reactants by high-speed centrifugation, leaving the solid fraction. Repeat the washing once to obtain acid-hydrolyzed chitin solid. Add the acid-hydrolyzed chitin solid to 200ml of purified water, add sodium hydroxide to adjust the pH of the alkaline carboxylation reaction solution to 12, add 0.15g of chloroacetic acid, and stir in a 65℃ water bath for 1h. After the reaction, add 800ml of purified water and separate by high-speed centrifugation at 10000r / min for 20 minutes. Repeat the washing once, discarding the supernatant each time and leaving the precipitate. Dialyze the precipitate obtained from the last centrifugation for 1 day, with water changes every 2h-4h. The dialyzed solution is sonicated (150W, 30min). The solution obtained by sonication is the nanoscale dispersion of surface-modified chitin whiskers. The dispersion obtained by ultrasound was freeze-dried for 24 hours to obtain 0.25 g of a sponge-like sample with surface-modified chitin whiskers. The method for preparing surface-modified chitin whiskers in this invention is as follows: Figure 1As shown, the main steps include acid hydrolysis starting from chitin raw material, centrifugal purification, hydroxymethylation modification, centrifugation-dialysis purification, sonication, and freeze drying.

[0037] 0.05 g of the freeze-dried surface-modified chitin whiskers prepared by the above method were analyzed by Fourier transform infrared spectroscopy, with the scanning range set to 4000 cm⁻¹. -1 ~600cm -1 The resolution is 4cm. -1 Scanned 10 times. Results are as follows: Figure 2 As shown, 1600cm -1 There is a distinct infrared absorption peak nearby, which is related to the C=O stretching vibration of the carboxyl group, indicating that carboxymethylated chitin whiskers were successfully prepared.

[0038] Example 2:

[0039] Preparation of surface-modified chitin whiskers: 2.5 g of chitin powder was weighed and acid-hydrolyzed in 85 ml of 3 mol / L sulfuric acid solution at 70 °C for 18 h. The reactants were washed by high-speed centrifugation, leaving the solid fraction. This washing process was repeated 5 times to obtain acid-hydrolyzed chitin solid. The acid-hydrolyzed chitin solid was added to 400 ml of purified water, and potassium hydroxide was added to adjust the pH of the alkaline carboxylation reaction solution to 13. Then, 1.5 g of chloroacetic acid was added, and the mixture was stirred in a 40 °C water bath for 4 h. After the reaction, 400 ml of purified water was added, and the mixture was separated by high-speed centrifugation at 3000 r / min for 60 minutes. This washing process was repeated 5 times. The precipitate obtained from the last centrifugation was dialyzed over 2 days, with water changes every 2-4 h. The dialyzed solution was then sonicated (600 W, 10 min). The resulting sonicated solution was the nanoscale dispersion of surface-modified chitin whiskers. The dispersion obtained by ultrasound was freeze-dried for 48 hours to obtain 1.1 g of surface-modified chitin whisker sponge-like sample.

[0040] The surface-modified chitin whiskers were added to a temperature-sensitive chitin gel, and the viscoelasticity of the resulting composite hydrogel at a shear frequency of 1 Hz was measured. Figure 3 As shown, the elastic modulus of the composite hydrogel increased from 150 Pa-350 Pa to 400 Pa-600 Pa, and the viscous modulus increased from 5 Pa-50 Pa to 10 Pa-100 Pa. This demonstrates that surface-modified chitin whiskers essentially retain the key structure of chitin whiskers and also possess the same function of enhancing the mechanical properties and shape stability of the matrix as chitin whiskers, thus serving as a reinforcing filler for composite materials.

[0041] Comparative Example 1:

[0042] Preparation of unmodified chitin whiskers using conventional methods: Unlike Example 2, after the acid hydrolysis reaction, purified water was added to dilute to 1000 ml, magnetically stirred for 10 minutes, and then allowed to stand for 3 hours. The supernatant was discarded, and this process was repeated 5 times. After the above operations, dialysis was performed for 4 days. The ultrasonic parameters of the dialysis solution were 600 W for 30 minutes. The resulting nanoscale dispersion of chitin whiskers was then freeze-dried for 72 hours to obtain 1.2 g of unmodified chitin whisker sponge-like sample.

[0043] The method of this invention prepares surface-modified chitin whiskers from chitin raw materials. The product yield is similar to that of chitin whiskers prepared by conventional methods. Furthermore, it effectively shortens the time spent on the settling, dialysis, and freeze-drying steps in production, reducing production costs and equipment wear. While significantly improving production efficiency, it also largely retains the key structural parameters of unmodified chitin whiskers and greatly improves dispersion performance. Specific statistics are shown in the table below:

[0044]

[0045] Take 0.1 g of the lyophilized surface-modified chitin whiskers prepared in Example 2, add them to 100 ml of purified water and ultrasonically disperse (600 W, 30 min). Also, weigh 0.1 g of the lyophilized unmodified chitin whiskers prepared by the conventional method in Comparative Example 1, add them to 100 ml of purified water and ultrasonically disperse (600 W, 30 min). The microstructure of the dispersed whisker samples was studied using transmission electron microscopy, and the results are as follows: Figure 4 As shown, both surface-modified chitin whiskers and chitin whiskers exhibit needle-like nanostructures, with essentially the same size and shape in their microstructures, showing no significant differences.

[0046] The surface-modified chitin whiskers prepared in Example 2 and the unmodified chitin whiskers prepared by the conventional method were subjected to crystallinity analysis using XRD. The peaks around 2θ = 12.7°, 19.3°, 20.8°, 23.4°, 26.4°, and 32.0° in the XRD patterns were identified as belonging to the (021), (110), (120), (101), (130), and (104) crystal planes of the chitin polymer, respectively. The crystallinity of ordinary chitin raw materials is mostly around 50%. The test results are as follows... Figure 5 As shown, through fitting, it was found that the crystallinity of surface-modified chitin whiskers was 87.5%, while that of unmodified chitin whiskers was 92.9%. The crystallinity of surface-modified chitin whiskers differed from that of unmodified chitin whiskers by only 5.8%, and was 75% higher than that of chitin raw materials. This indicates that the internal structure of surface-modified chitin whiskers is basically the same as that of unmodified chitin whiskers, and they have an ultra-high crystallinity close to that of unmodified chitin whiskers.

[0047] Surface-modified chitin whiskers prepared in Example 2 and unmodified chitin whiskers prepared by conventional methods were used to test their particle size distribution using a nanoparticle size analyzer. Before testing, both were prepared into 1 mg / ml dispersions, and then the samples were transferred to quartz cuvettes for testing. The test results are as follows. Figure 6 As shown, the surface-modified chitin whiskers not only have a more concentrated grain size distribution, but also have an average grain size of approximately 2*10. 3 The average particle size of unmodified chitin whiskers prepared by conventional methods is approximately 2*10. 4 The average particle size of surface-modified chitin whiskers is only 10% of that of unmodified chitin whiskers, which means that the aggregation of surface-modified chitin whiskers in solution is reduced by 90% compared to unmodified chitin whiskers.

[0048] like Figure 7 As shown, the surface-modified chitosan whiskers of Example 2 were prepared into a 1 mg / ml solution and sonicated at 600 W for 5 min. Then, the unmodified chitosan whiskers of Comparative Example 1 were prepared into a 1 mg / ml solution and sonicated at 600 W for 5 min. Figure 7 As shown, the dispersion effect of unmodified chitin whiskers is significantly worse than that of surface-modified chitin whiskers, with obvious turbidity. This indicates that surface-modified chitin whiskers have much better ultrasonic dispersion performance than unmodified chitin whiskers. In practice, unmodified chitin whiskers require ultrasonication at 600W power for 30 minutes, while surface-modified chitin whiskers have high ultrasonic efficiency, saving more than 80% of the time.

[0049] Comparative Example 2:

[0050] Unlike Example 1, the chitin powder was subjected to an acid hydrolysis reaction at a temperature of 60°C.

[0051] Comparative Example 3:

[0052] Unlike Example 1, the pH of the alkaline carboxylation reaction solution was adjusted to 14.

[0053] Comparative Example 4:

[0054] Unlike Example 1, the total amount of chloroacetic acid added was 0.5g.

[0055] Comparative Example 5:

[0056] Unlike Example 1, the reaction temperature was adjusted to 30°C.

[0057] Comparative Example 6:

[0058] Unlike Example 1, the speed of the high-speed centrifuge was adjusted to 2000 r / min.

[0059] Comparative Example 7:

[0060] The feeding ratio, reaction temperature, reaction time, acidity / alkalinity, and centrifugation speed in the surface modification method of this invention all affect the dispersion performance of the final surface-modified chitin whiskers. Using a fixed ultrasonic parameter of 600W for 5 minutes, the surface-modified chitin whiskers from Examples 1 and 2 and Comparative Examples 3, 4, 5, 6, and 7 were prepared at a concentration of 1 mg / ml and subjected to ultrasonic treatment. The presence of visible insoluble matter in the final ultrasonically dispersed solution and the presence of the Tyndall effect under infrared light irradiation were used to determine whether the solution achieved nanoscale dispersion. This determined the parameter range in the technical solution of this invention, as shown in the table below.

[0061]

[0062]

[0063] Comparative Example 8:

[0064] Samples from Example 1 and Comparative Example 1 were weighed and prepared into 1 mg / ml surface-modified chitin whisker dispersions and 1 mg / ml unmodified chitin whisker dispersions, respectively. These were then sonicated at 600 W for 5 min. The mixtures were then mixed with different concentrations of active ingredients, including 1% propylene glycol, 4% glycerol, 1% PEG, 0.1% chitosan, 0.25% arginine, 0.5% nicotinamide, 0.5% carboxymethyl chitosan, 0.2% disodium EDTA, and 0.5% p-hydroxyacetophenone. Except for alcohols, the chitin whisker solutions quickly precipitated, settled, or formed flocs upon contact with other components. However, the mixed solutions of surface-modified chitin whiskers and various active ingredients remained stable for two weeks. Some mixing results are shown below. Figure 8 As shown, no obvious flocculent matter or precipitation was observed during the process. The specific results are summarized in the table below, demonstrating that surface-modified chitin whiskers exhibit better stability and compatibility than regular chitin whiskers.

[0065]

[0066]

[0067] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing surface-modified chitin whiskers, characterized in that, Includes the following steps: Step 1: Preparation of chitin by acid hydrolysis: Chitin powder is mixed with acid solution and heated and stirred to allow it to react fully. After the reaction stops, purified water is added and the supernatant is removed by high-speed centrifugation. The supernatant is then washed 1-5 times by centrifugation. The remaining solid is acid hydrolyzed chitin. Step 2, Carboxymethylation modification: Add acid-hydrolyzed chitin to purified water, the reaction temperature is 40℃-65℃, the mass ratio of chitin to chloroacetic acid is 1:0.3-0.6, then add sodium hydroxide or potassium hydroxide to prepare a specific alkaline carboxylation reaction solution, and stir the reaction. Step 3: After the reaction in Step 2 is completed, add purified water and remove the supernatant by high-speed centrifugation. Then, repeat the washing process by centrifugation 1-5 times to obtain the washed solid. Step 4: Add purified water to the solid obtained in Step 3 and dialyze it. After dialyzing, sonicate it. The final aqueous solution is the dispersion of surface-modified chitin whiskers. Freeze-dry it to obtain a sponge-like sample of surface-modified chitin whiskers. In step one, the acid solution is a sulfuric acid solution, the mass ratio of chitosan powder to sulfuric acid solute is 1:8-10, and the specific reaction conditions between chitosan powder and the sulfuric acid solution are: reaction temperature of 70℃-90℃ and reaction time of 9h-18h. In step two, the pH of the alkaline carboxylation reaction solution is adjusted to 12-13 using sodium hydroxide or potassium hydroxide, and the reaction time is 1-4 hours. In step three, the amount of purified water added is 1-5 times the total volume of the mixed solution. The high-speed centrifugation speed is 3000 r / min-10000 r / min, and the centrifugation time is 20 min-60 min. The repeated washing method is as follows: add purified water and centrifuge at high speed to remove the supernatant. The centrifugation parameters are the same as above.

2. The method for preparing surface-modified chitin whiskers according to claim 1, characterized by: In step one, the amount of purified water added is 1-5 times the total volume of the mixed solution, the high-speed centrifugation speed is 3000r / min-10000r / min, and the centrifugation time is 20min-60min. The repeated washing method is as follows: add purified water and centrifuge at high speed to remove the supernatant, with the same centrifugation parameters as above.

3. Process for the preparation of surface-modified chitin whiskers according to claim 1 or 2, characterized in that: In step four, the total dialysis time is 1-2 days, with a water change interval of 2-4 hours. The ultrasonic parameters for the dialysis solution are 150W-600W for 5-30 minutes. The final aqueous solution is the dispersion of surface-modified chitin whiskers. The dispersion is then freeze-dried for 24-48 hours to obtain a sponge-like sample of surface-modified chitin whiskers.

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