Process for the preparation of an amino-dextran and its use

Abstract

The application belongs to the technical field of polymer chemistry, and particularly relates to a preparation method and application of aminated dextran. The preparation method comprises the following steps: under nitrogen protection, dextran 70 is dissolved in dimethyl sulfoxide, then N,N-carbonyldiimidazole dimethyl sulfoxide solution is added, mixed, added into ethylenediamine dimethyl sulfoxide solution, reacted at 20-30 DEG C, nitrogen is removed, quenched, ultrafiltrated, freeze-dried, and the crosslinked aminated dextran is obtained. Experimental results show that the crosslinked aminated dextran prepared by the application has better liquid absorption capacity; the application has mild reaction conditions, simple operation, low raw material price, high yield and high purity of the product aminated dextran, is suitable for industrial production, and has obvious advantages compared with the method for preparing dextran in the prior art.

Description

Technical Field

[0001] This invention belongs to the field of polymer chemistry technology, specifically relating to a method for preparing and applying ammoniated dextran. Background Technology

[0002] Dextran, also known as glucan, is a high-molecular-weight glucose polymer formed by the dehydration and polymerization of glucose units in sucrose molecules through fermentation by *Leuconostoc membranaceus*. Dextran is widely found in nature in microorganisms and their secretions, and is an important component of cell walls. It is frequently found in uncleaned parts of equipment in sugarcane and beet sugar factories, with sucrose being the primary source. Dextran decomposes in strong acids, its end groups are easily oxidized in alkaline solutions, and it gradually changes color or decomposes upon heating.

[0003] Dextran and its derivatives have been widely used in medicine, industry, food, and other fields due to their safety, non-toxicity, and other advantages, resulting in huge market demand. Dextran with different molecular weights has different medicinal values ​​and biological functions. Medium-molecular-weight dextran with a weight-average molecular weight of 20-70 kDa is the most commonly used pharmaceutical-grade dextran in clinical practice, mainly as a plasma substitute for treating hemorrhagic shock, traumatic shock, and burn shock. Low-molecular-weight dextran with a weight-average molecular weight of 6-8 kDa is an excellent material for preparing dextran iron. Small-molecular-weight dextran with a weight-average molecular weight of 3-5 kDa can be sulfated, and the resulting derivatives can be used in medicine for antithrombotic purposes.

[0004] The traditional process for the production of dextran is as follows: (1) fermentation, (2) acid hydrolysis, (3) activated carbon decolorization, (4) ethanol fractionation precipitation, (5) activated carbon decolorization, (6) filtration to remove activated carbon, and (7) drying.

[0005] Chinese invention patent application CN101205551A discloses a method for producing crude dextran using immobilized Leuconostoc mesenteroides. The method includes the following steps: a) mixing: 90 mL of 8% polyvinyl alcohol composite gel is mixed with 6-15 mL of Leuconostoc mesenteroides bacterial solution at room temperature, stirred evenly, and poured into a petri dish to a thickness of 4-10 mm; b) freezing and cutting: the mixture is frozen at -24℃ for 48 hours, and after solidification, it is thawed naturally and cut into small pieces of 8 mm × 8 mm × 8 mm; c) fermentation production: immobilized Leuconostoc mesenteroides is added to the production culture medium at a carrier addition rate of 8%-15% by weight, and crude dextran is produced by fermentation at 25℃. This method suffers from high production costs and low bacterial activity.

[0006] Another Chinese invention patent application, CN101205256A, discloses a production process for dextran 5. This process uses four-stage membrane filtration and molecular weight degradation and decolorization steps to obtain dextran 5. The process is complex. The organic membranes in this process cannot withstand high temperatures, and the feed solution needs to be cooled during the process, resulting in high energy consumption. Furthermore, the membranes are difficult to clean, have short lifespans, and require frequent replacement.

[0007] The main disadvantages of traditional processes are: (1) They require a large amount of ethanol, resulting in high costs and safety hazards. (2) Ethanol fractionation and precipitation takes a long time, and ethanol recovery consumes a lot of energy. (3) The materials in traditional processes are mostly gel-like and cannot be transported by pipelines, requiring manual handling and making automation impossible. (4) The product purity is low, around 60%.

[0008] In summary, how to improve the preparation process of dextran, reduce costs, and achieve industrial production is an urgent problem to be solved. Summary of the Invention

[0009] This invention addresses the problems existing in the prior art by providing a method for preparing and applying ammoniated dextran.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing ammoniated dextran includes the following steps: under nitrogen protection, dextran 70 is dissolved in dimethyl sulfoxide, then N,N-carbazyldiimidazole in dimethyl sulfoxide solution is added, mixed, added to dimethyl sulfoxide solution of ethylenediamine, reacted at 20-30℃, nitrogen is removed, quenched, ultrafiltered, and freeze-dried to obtain the product.

[0011] Preferably, the dextran 70 dissolves in dimethyl sulfoxide at a temperature of 55-65°C.

[0012] Preferably, the temperature of the dimethyl sulfoxide solution containing N,N-carbonyldiimidazole is 20-30°C, and the dropping rate is 60-200 mL / min.

[0013] Preferably, the mixing temperature is 20-30℃, the mixing time is 3.5-4.5h, and the mixing speed is 300-600rpm.

[0014] Preferably, the reaction time is 23-25 ​​hours.

[0015] Preferably, the reaction requires stirring, and the stirring speed is 300-600 rpm.

[0016] Preferably, the mass-to-volume ratio of dimethyl sulfoxide, dextran 70, N,N-carbodiimidazole and ethylenediamine is 3500-4500mL:150-250g:150-250g:80-100g.

[0017] Preferably, the quenching solvent is water, the ultrafiltration uses cellulose material with a molecular weight cutoff of 10,000 Da as the filter bag, and the conductivity of the ultrafiltration effluent is ≤10 μs / cm.

[0018] Preferably, the ultrafiltration is followed by filtration, and the filtration uses a 0.45μm aqueous filter membrane.

[0019] Preferably, the freeze-drying temperature is -75℃ to -20℃, and the freeze-drying time is 24-72 hours.

[0020] The present invention also provides an ammoniated dextran prepared by the above preparation method, wherein the structural formula of the ammoniated dextran is shown in Formula 1:

[0021] In Formula 1, the weight-average molecular weight of the ammoniated dextran is 64,000-76,000 Da, and the degree of ammoniation is 10-25%.

[0022] The present invention also provides the application of the ammoniated dextran prepared by the above preparation method in the preparation of aqueous liquid absorbent materials.

[0023] Compared with the prior art, the present invention has the following beneficial effects: (1) By controlling the reaction temperature, the present invention improves the yield and purity of ammoniated dextran with an ammoniation degree of 10-25%; by selecting specific post-treatment methods, the present invention also improves the yield and purity of ammoniated dextran.

[0024] (2) Experimental results show that the cross-linked amino-coated dextran prepared in this invention has a strong liquid absorption capacity.

[0025] (3) The reaction conditions of this invention are mild, the operation is simple, the raw material price is low, the product yield is high and the purity is high, making it suitable for industrial production. Compared with the existing methods for preparing dextran, it has obvious advantages. Attached Figure Description

[0026] Figure 1 The proton NMR spectrum of the ammoniated dextran prepared in Example 1 ( 1 H NMR).

[0027] Figure 2 The proton NMR spectrum of the ammoniated dextran prepared in Example 2 ( 1 H NMR).

[0028] Figure 3 The 1H NMR spectrum of the ammoniated dextran prepared in Example 3 ( 1 H NMR).

[0029] It is worth noting that the lack of clarity in the accompanying drawings does not affect the understanding of the technical solution of the present invention by those skilled in the art. Detailed Implementation

[0030] It is worth noting that the raw materials used in this invention are all commercially available products. Specifically, dextran 70 was purchased from Shanghai Huamao Pharmaceutical Co., Ltd.; dimethyl sulfoxide, analytical grade, was purchased from Tianjin Fuyu Fine Chemical Co., Ltd.; and N,N-carbonyldiimidazole (CDI), 99% pure, was purchased from Shandong Xiya Chemical Industry Co., Ltd.

[0031] Example 1 The preparation process of an ammoniated dextran is as follows: (1) Under nitrogen protection, add 2000 mL of dimethyl sulfoxide to a 5 L reaction flask and start stirring. Add 200 g of dextran 70 and add the remaining 400 mL of dimethyl sulfoxide. After adding, stir and heat to 60 °C. As the temperature rises, it gradually dissolves and becomes clear, resulting in a dimethyl sulfoxide solution of dextran 70.

[0032] (2) Under nitrogen protection, weigh 200g of N,N-carbonyldiimidazole (CDI), dissolve it in 1000mL of dimethyl sulfoxide until clear, and add it dropwise at 25℃ for 10min to the dimethyl sulfoxide solution of dextran 70 in step (1). After the addition is complete, keep warm at 25℃ and stir at 600rpm for 4h to obtain the reaction solution of dextran 70.

[0033] (3) Under nitrogen protection, weigh 89.9 g (100 mL) of ethylenediamine into a 20 L reaction flask, then add 600 mL of dimethyl sulfoxide for dilution, mix well, and then add the reaction solution of dextran 70 obtained in step (2) dropwise into the 20 L reaction flask (dimethyl sulfoxide solution of ethylenediamine), keep warm at 25 °C, protect from light, and stir at 400 rpm for 24 h.

[0034] (4) After the reaction is complete, stop the nitrogen protection, keep the temperature at 25°C, add 6.15L of purified water dropwise to quench the reaction, and then perform ultrafiltration on the solution. The filter material is cellulose with a molecular weight cutoff of 10,000. During the ultrafiltration process, try to keep the inflow and outflow rates consistent and the total volume of the ultrafiltration solution as constant as possible. Ultrafiltration continues until the conductivity of the outflow is 9.2μs / cm. Based on the amount of solution used, continue ultrafiltration for 5 times the volume (approximately 51.5L based on the total amount of purified water added at the time of feeding) and then stop ultrafiltration. Filter through a 0.45μm aqueous filter membrane and freeze-dry at -75°C for 24 hours to obtain the solution. The yield is 94.6% and the purity is 98%.

[0035] The ammoniated dextran prepared in this example 1 H NMR spectrum, such as Figure 1 As shown.

[0036] Example 2 The preparation process of an ammoniated dextran is as follows: (1) Under nitrogen protection, add 2000 mL of dimethyl sulfoxide to a 5 L reaction flask and start stirring. Add 200 g of dextran 70 and add the remaining 400 mL of dimethyl sulfoxide. After adding, stir and heat to 60 °C. As the temperature rises, it gradually dissolves and becomes clear, resulting in a dimethyl sulfoxide solution of dextran 70.

[0037] (2) Under nitrogen protection, weigh 200g of N,N-carbonyldiimidazole (CDI), dissolve it in 1000mL of dimethyl sulfoxide until clear, and add it dropwise at 25℃ for 10min to the dimethyl sulfoxide solution of dextran 70 in step (1). After the addition is complete, keep warm at 25℃ and stir at 400rpm for 4h to obtain the reaction solution of dextran 70.

[0038] (3) Under nitrogen protection, weigh 89.9 g (100 mL) of ethylenediamine into a 20 L reaction flask, then add 600 mL of dimethyl sulfoxide for dilution, mix well, and then add the reaction solution of dextran 70 obtained in step (2) dropwise into the 20 L reaction flask (dimethyl sulfoxide solution of ethylenediamine), keep warm at 30 °C, protect from light, and stir at 600 rpm for 23 h.

[0039] (4) After the reaction is complete, stop the nitrogen protection, keep the temperature at 25°C, add 6.15L of purified water dropwise to quench the reaction, and then perform ultrafiltration on the solution. The filter material is cellulose with a molecular weight cutoff of 10,000. During the ultrafiltration process, try to keep the inflow and outflow rates consistent and the total volume of the ultrafiltration solution as constant as possible. Ultrafiltration continues until the conductivity of the outflow is 9.9 μs / cm. Based on the amount of solution used, continue ultrafiltration for 5 times the volume (approximately 51.5L based on the total amount of purified water added at the time of feeding) and then stop ultrafiltration. Filter through a 0.45μm aqueous filter membrane and freeze-dry at -55°C for 46 hours to obtain the solution. The yield is 91.9% and the purity is 96%.

[0040] The ammoniated dextran prepared in this example 1 H NMR spectrum, such as Figure 2 As shown.

[0041] Example 3 The preparation process of an ammoniated dextran is as follows: (1) Under nitrogen protection, add 2000 mL of dimethyl sulfoxide to a 5 L reaction flask and start stirring. Add 200 g of dextran 70 and add the remaining 400 mL of dimethyl sulfoxide. After adding, stir and heat to 60 °C. As the temperature rises, it gradually dissolves and becomes clear, resulting in a dimethyl sulfoxide solution of dextran 70.

[0042] (2) Under nitrogen protection, weigh 200g of N,N-carbonyldiimidazole (CDI), dissolve it in 1000mL of dimethyl sulfoxide until clear, and add it dropwise at 25℃ for 10min to the dimethyl sulfoxide solution of dextran 70 in step (1). After the addition is complete, keep warm at 25℃ and stir at 500rpm for 4h to obtain the reaction solution of dextran 70.

[0043] (3) Under nitrogen protection, weigh 89.9 g (100 mL) of ethylenediamine into a 20 L reaction flask, then add 600 mL of dimethyl sulfoxide for dilution, mix well, and then add the reaction solution of dextran 70 obtained in step (2) dropwise into the 20 L reaction flask (dimethyl sulfoxide solution of ethylenediamine), keep warm at 20 °C, protect from light, and stir at 500 rpm for 25 h.

[0044] (4) After the reaction is complete, stop the nitrogen protection, keep the temperature at 25°C, add 6.15L of purified water dropwise to quench the reaction, and then perform ultrafiltration on the solution. The filter material is cellulose with a molecular weight cutoff of 10,000. During the ultrafiltration process, try to keep the inflow and outflow rates consistent and the total volume of the ultrafiltration solution as constant as possible. Ultrafiltration continues until the conductivity of the outflow is 9.0 μs / cm. Based on the amount of solution used, continue ultrafiltration for 5 times the volume (approximately 51.5L based on the total amount of purified water added at the time of feeding) and then stop ultrafiltration. Filter through a 0.45μm aqueous filter membrane and freeze-dry at -20°C for 48 hours to obtain the solution. The yield is 92.6% and the purity is 97%.

[0045] The ammoniated dextran prepared in this example 1 H NMR spectrum, such as Figure 3 As shown.

[0046] Comparative Example 1 Same as Example 1, except that the reaction temperature is different in step (3).

[0047] The preparation process of an ammoniated dextran is as follows: (1) Under nitrogen protection, add 2000 mL of dimethyl sulfoxide to a 5 L reaction flask and start stirring. Add 200 g of dextran 70 and add the remaining 400 mL of dimethyl sulfoxide. After adding, stir and heat to 60 °C. As the temperature rises, it gradually dissolves and becomes clear, resulting in a dimethyl sulfoxide solution of dextran 70.

[0048] (2) Under nitrogen protection, weigh 200g of N,N-carbonyldiimidazole (CDI), dissolve it in 1000mL of dimethyl sulfoxide until clear, and add it dropwise at 25℃ for 10min to the dimethyl sulfoxide solution of dextran 70 in step (1). After the addition is complete, keep warm at 25℃ and stir at 600rpm for 4h to obtain the reaction solution of dextran 70.

[0049] (3) Under nitrogen protection, weigh 89.9 g (100 mL) of ethylenediamine into a 20 L reaction flask, then add 600 mL of dimethyl sulfoxide for dilution, mix well, and then add the reaction solution of dextran 70 obtained in step (2) dropwise into the 20 L reaction flask (dimethyl sulfoxide solution of ethylenediamine), keep warm at 40 °C, protect from light, and stir at 400 rpm for 24 h.

[0050] (4) After the reaction is complete, stop the nitrogen protection, keep the temperature at 25°C, add 6.15L of purified water dropwise to quench the reaction, and then perform ultrafiltration on the solution. The filter material is cellulose with a molecular weight cutoff of 10,000. During the ultrafiltration process, try to keep the inflow and outflow rates consistent and the total volume of the ultrafiltration solution as constant as possible. Ultrafiltration continues until the conductivity of the outflow is 9.2μs / cm. Based on the amount of solution used, continue ultrafiltration for 5 times the volume (approximately 51.5L based on the total amount of purified water added at the time of feeding) and then stop ultrafiltration. Filter through a 0.45μm aqueous filter membrane and freeze-dry at -75°C for 24 hours to obtain the solution. The yield is 79.2% and the purity is 90%.

[0051] Comparative Example 2 Same as Example 1, except that ultrafiltration is replaced with nanofiltration.

[0052] The preparation process of an ammoniated dextran is as follows: (1) Under nitrogen protection, add 2000 mL of dimethyl sulfoxide to a 5 L reaction flask and start stirring. Add 200 g of dextran 70 and add the remaining 400 mL of dimethyl sulfoxide. After adding, stir and heat to 60 °C. As the temperature rises, it gradually dissolves and becomes clear, resulting in a dimethyl sulfoxide solution of dextran 70.

[0053] (2) Under nitrogen protection, weigh 200g of N,N-carbonyldiimidazole (CDI), dissolve it in 1000mL of dimethyl sulfoxide until clear, and add it dropwise at 25℃ for 10min to the dimethyl sulfoxide solution of dextran 70 in step (1). After the addition is complete, keep warm at 25℃ and stir at 600rpm for 4h to obtain the reaction solution of dextran 70.

[0054] (3) Under nitrogen protection, weigh 89.9 g (100 mL) of ethylenediamine into a 20 L reaction flask, then add 600 mL of dimethyl sulfoxide for dilution, mix well, and then add the reaction solution of dextran 70 obtained in step (2) dropwise into the 20 L reaction flask (dimethyl sulfoxide solution of ethylenediamine), keep warm at 25 °C, protect from light, and stir at 400 rpm for 24 h.

[0055] (4) After the reaction is complete, stop the nitrogen protection, keep the temperature at 25°C, add 6.15L of purified water dropwise to quench the reaction, and then perform nanofiltration on the solution. The filter material is polyethersulfone with a molecular weight cutoff of 3000. During nanofiltration, try to keep the inflow and outflow rates consistent and the total volume of the nanofiltration solution as constant as possible. Nanofiltration continues until the conductivity of the outflow is 9.2μs / cm. Then, continue nanofiltration for 5 times the volume of solution (approximately 51.5L based on the total amount of purified water added at the time of feeding) and stop nanofiltration. Filter through a 0.45μm aqueous filter membrane and freeze-dry at -75°C for 24 hours to obtain the solution. The yield is 74.5% and the purity is 91%.

[0056] Comparative Example 3 Similar to Example 1, the only difference is that the conductivity of the ultrafiltration effluent is different in step (4).

[0057] The preparation process of an ammoniated dextran is as follows: (1) Under nitrogen protection, add 2000 mL of dimethyl sulfoxide to a 5 L reaction flask and start stirring. Add 200 g of dextran 70 and add the remaining 400 mL of dimethyl sulfoxide. After adding, stir and heat to 60 °C. As the temperature rises, it gradually dissolves and becomes clear, resulting in a dimethyl sulfoxide solution of dextran 70.

[0058] (2) Under nitrogen protection, weigh 200g of N,N-carbonyldiimidazole (CDI), dissolve it in 1000mL of dimethyl sulfoxide until clear, and add it dropwise at 25℃ for 10min to the dimethyl sulfoxide solution of dextran 70 in step (1). After the addition is complete, keep warm at 25℃ and stir at 600rpm for 4h to obtain the reaction solution of dextran 70.

[0059] (3) Under nitrogen protection, weigh 89.9 g (100 mL) of ethylenediamine into a 20 L reaction flask, then add 600 mL of dimethyl sulfoxide for dilution, mix well, and then add the reaction solution of dextran 70 obtained in step (2) dropwise into the 20 L reaction flask (dimethyl sulfoxide solution of ethylenediamine), keep warm at 25 °C, protect from light, and stir at 400 rpm for 24 h.

[0060] (4) After the reaction is complete, stop the nitrogen protection, keep the temperature at 25°C, add 6.15L of purified water dropwise to quench the reaction, and then perform ultrafiltration on the solution. The filter material is cellulose with a molecular weight cutoff of 10,000. During the ultrafiltration process, try to keep the inflow and outflow rates consistent and the total volume of the ultrafiltration solution as constant as possible. Ultrafiltration continues until the conductivity of the outflow is 26.6μs / cm. Based on the amount of solution used, continue ultrafiltration for 5 times the volume (approximately 51.5L based on the total amount of purified water added at the time of feeding) and then stop ultrafiltration. Filter through a 0.45μm aqueous filter membrane and freeze-dry at -75°C for 24 hours to obtain the solution. The yield is 72.3% and the purity is 92%.

[0061] Comparative Example 4 Same as Example 1, except for the different raw material ratios.

[0062] The preparation process of an ammoniated dextran is as follows: (1) Under nitrogen protection, add 2000 mL of dimethyl sulfoxide to a 5 L reaction flask and start stirring. Add 300 g of dextran 70 and add the remaining 400 mL of dimethyl sulfoxide. After adding, stir and heat to 60 °C. As the temperature rises, it gradually dissolves and becomes clear, resulting in a dimethyl sulfoxide solution of dextran 70.

[0063] (2) Under nitrogen protection, weigh 80g of N,N-carbonyldiimidazole (CDI), dissolve it in 1000mL of dimethyl sulfoxide until clear, and add it dropwise at 25℃ for 10min to the dimethyl sulfoxide solution of dextran 70 in step (1). After the addition is complete, keep warm at 25℃ and stir at 600rpm for 4h to obtain the reaction solution of dextran 70.

[0064] (3) Under nitrogen protection, weigh 100g of ethylenediamine into a 20L reaction flask, then add 1000mL of dimethyl sulfoxide for dilution. After mixing, add the reaction solution of dextran 70 obtained in step (2) dropwise into the 20L reaction flask (dimethyl sulfoxide solution of ethylenediamine), keep warm at 25℃, protect from light, and stir at 400rpm for 24h.

[0065] (4) After the reaction is complete, stop the nitrogen protection, keep the temperature at 25°C, add 6.15L of purified water to quench the reaction, and then perform ultrafiltration on the solution. The filter material is cellulose with a molecular weight cutoff of 10,000. During the ultrafiltration process, try to keep the inflow and outflow rates consistent and the total volume of the ultrafiltration solution as constant as possible. Ultrafiltration continues until the conductivity of the outflow is 9.2μs / cm. Continue ultrafiltration for 5 times the volume of solution used and then stop ultrafiltration. Filter through a 0.45μm aqueous filter membrane and freeze-dry at -75°C for 24 hours to obtain the solution. The yield is 78.1% and the purity is 87%.

[0066] Physicochemical property determination The degree of amination and molecular weight of the amination dextran prepared in Examples 1-3 and Comparative Examples 1-4 were determined according to the quality standard of dextran in the General Chapter of the 2020 edition of the Chinese Pharmacopoeia. The results are shown in Table 1.

[0067] Table 1. Results of physical property determination of ammoniated dextran

[0068] Experimental Example 1 0.2 g of boric acid was dissolved in 5 mL of water. A 5% NaOH solution was added to adjust the pH to 10, and then water was added to bring the total solution volume to 15 mL. The ammoniated dextran (1.0 g) prepared in Examples 1-3 and Comparative Examples 1-4 was added to this solution with stirring. The preparation was left to stand overnight at room temperature and dried to obtain a solid, which was boric acid crosslinked ammoniated dextran. The absorbance under load (AUL) and centrifugal retention capacity (CRC) of the product were then measured using a 0.9% NaCl solution.

[0069] Measurement of absorbance under load (AUL): The boric acid crosslinked aminodextrose anhydride prepared in Examples 1-3 and Comparative Examples 1-4 was measured according to the procedure disclosed in EDANA standard test WSP242.2.R3(12).

[0070] Measurement of centrifugation retention capacity (CRC): 100 mg of boric acid-crosslinked aminodecyl anhydride prepared in Examples 1-3 and Comparative Examples 1-4 was heat-sealed into a weighed 50 mm × 80 mm tea bag and immersed in a 0.9 wt% NaCl solution for 30 min. The NaCl solution was used to simulate urine. The tea bag was then placed in a basket centrifuge and rotated at 3000 rpm for 5 min.

[0071] The formula for calculating the centrifugation retention capacity (CRC, g of liquid retained per g of dry polymer) is as follows: Centrifugation Retention Capacity (CRC) = [(Weight of tea bag and polymer after centrifugation) - (3 × weight of dry tea bag + weight of dry polymer)] / weight of dry polymer The measurement results are shown in Table 2. The absorbance under load (AUL) and centrifugal retention capacity (CRC) of the boric acid crosslinked aminated dextran prepared in Examples 1-3 are higher than those of Comparative Examples 1-4. It can be seen that the higher the degree of ammoniation, the better the crosslinking performance of the boric acid crosslinked aminated dextran, indicating that the crosslinked aminated dextran prepared in this invention has a strong liquid absorption capacity.

[0072] Table 2. Measurement results of absorbance (AUL) and centrifugal retention capacity (CRC) under load.

[0073] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing ammoniated dextran, characterized in that, The process includes the following steps: Under nitrogen protection, dextran 70 is dissolved in dimethyl sulfoxide, then N,N-carbonyldiimidazole in dimethyl sulfoxide solution is added, mixed, and then added to ethylenediamine in dimethyl sulfoxide solution. The reaction is carried out at 20-30℃, nitrogen is removed, the mixture is quenched, ultrafiltered, and freeze-dried to obtain the final product. The mass-to-volume ratio of dimethyl sulfoxide, dextran 70, N,N-carbodiimidazole and ethylenediamine is 3500-4500mL:150-250 g:150-250 g:80-100 g; The ultrafiltration uses cellulose material with a molecular weight cutoff of 10,000 Da as the filter bag, and the conductivity of the ultrafiltration effluent is ≤10 μs / cm.

2. The preparation method according to claim 1, characterized in that, The dextran 70 dissolves in dimethyl sulfoxide at a temperature of 55-65°C.

3. The preparation method according to claim 1, characterized in that, The temperature of the dimethyl sulfoxide solution containing N,N-carbonyldiimidazole added is 20-30℃, and the dropping rate is 60-200 mL / min.

4. The preparation method according to claim 1, characterized in that, The mixing temperature is 20-30℃, the mixing time is 3.5-4.5 h, and the mixing speed is 300-600 rpm.

5. The preparation method according to claim 1, characterized in that, The reaction time is 23-25 ​​h.

6. The preparation method according to claim 1, characterized in that, The reaction requires stirring, and the stirring speed is 300-600 rpm.

7. The preparation method according to claim 1, characterized in that, The solvent used for quenching is water.

8. The preparation method according to claim 1, characterized in that, The ultrafiltration is followed by filtration, which uses a 0.45 µm aqueous filter membrane. The freeze-drying temperature is -75℃ to -20℃, and the freeze-drying time is 24-72 h.

9. The application of an ammoniated dextran prepared by the preparation method according to any one of claims 1-8 in the preparation of aqueous liquid absorbent materials.

Images