A superabsorbent porous gel foam material and a method for making the same

Abstract

The present application relates to hydrogel foam material technical field, specifically relates to a kind of preparation method of high water absorption porous gel foam material.The method specifically is that acrylic acid, acrylamide, methyl cellulose are sequentially dispersed and dissolved in cellulose nanofiber dispersion to obtain precast liquid A;Sodium bicarbonate is saturated and dissolved in cellulose nanofiber dispersion, and photo initiator is added and mixed uniformly, to obtain precast liquid B;Preparation liquid A and precast liquid B are injected into the same sealed container according to the volume ratio of 1:1 and mixed, and reaction generates foam;Then the foam is treated by ultraviolet radiation, so that it carries out radiation crosslinking reaction, and gel foam is obtained;Finally, the obtained gel foam is soaked in glycerol, ethanol mixed solution, then it is taken out and drained, and high water absorption porous gel foam material is obtained by normal pressure drying.The preparation method of the present application does not involve complex equipment, and the process is simple and easy to operate.The prepared foam material has high water absorption.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydrogel foam materials, in particular to a high-water-absorption porous gel foam material and a preparation method thereof. BACKGROUND

[0002] High water-absorption materials can absorb and fix tens or even hundreds of times of water, and are widely used in industry and agriculture due to their high water-absorption and swelling capacity. High water-absorption foam materials with overall porous structure not only have super water-absorption performance, but also have the advantages of strong structural integrity, high safety in use, and fast water-absorption speed, so that such materials have unique advantages in many fields such as medical health and food industry.

[0003] Gel foam is a kind of polymer porous material, which has high hydrophilicity and overall porous structure, and can be used as a high water-absorption material. The gel foam has an overall porous structure of 10-1000 μm continuous bubbles while maintaining the original physicochemical properties, and the porosity is more than 80%, which brings the gel foam the advantages of low density, excellent absorption performance, and large surface area. At the same time, the gel material itself can provide biodegradability, biocompatibility, antibacterial property and other functions, and has wide application prospects.

[0004] Gel foam materials are usually prepared by freeze-drying or supercritical drying method. Through the drying process under specific conditions, the water in the hydrogel is removed and a continuous porous structure is formed. Freeze-drying is a process in which the hydrogel is frozen below the eutectic temperature, and the water in the hydrogel is removed by sublimation in a vacuum environment. However, this method has the disadvantages of long process time and high energy consumption. Supercritical drying is a method in which liquid CO2 is used to replace the water in the gel, and a porous structure is formed after the release of liquid CO2 in the supercritical state. However, this method has the limitations of harsh preparation conditions and high equipment requirements. Both of these two methods cannot be carried out under normal pressure, which leads to high production cost and limits the large-scale and low-cost application of gel foam materials. In contrast, if gel foam materials can be prepared by drying under normal pressure, the production cost of such materials will be effectively reduced, and the market expansion will be facilitated.

[0005] At present, the normal pressure drying preparation of gel foam is carried out by adjusting the composition or structure of the hydrogel, designing a special support structure to overcome the collapse of the mesh caused by surface tension during the drying process, or taking additional auxiliary methods to reduce the surface tension to improve the material quality. These methods have limitations in cost, process conditions and application.

[0006] Therefore, it is necessary to develop a low-cost and simple process for preparing gel foam materials. SUMMARY

[0007] To address the aforementioned technical problems, this invention proposes a method for preparing a high-absorbency porous gel foam material that is low-cost and simple to prepare. This method is carried out under normal pressure, which not only reduces the preparation cost but also simplifies the process, thus possessing significant practical value and application potential.

[0008] The technical solution adopted by this invention to solve its technical problem is:

[0009] A method for preparing a porous gel foam material with high water absorption rate, the preparation method specifically includes the following steps:

[0010] (1) Acrylic acid, acrylamide, and methylcellulose are sequentially dispersed and dissolved in a cellulose nanofiber dispersion with a solid content of 0.5-2%; the total molar concentration of acrylic acid and acrylamide is 7-8 mol / L; finally, a crosslinking agent is added to the mixed dispersion and mixed evenly to obtain pre-prepared solution A; the mass of methylcellulose accounts for 0.1-0.3% of the total mass of pre-prepared solution A;

[0011] (2) Sodium bicarbonate is saturated and dissolved in a cellulose nanofiber dispersion with a solid content of 0.5-2%. Then, a photoinitiator is added to the mixed dispersion and mixed evenly to obtain pre-prepared solution B.

[0012] (3) Using a dual-channel syringe, pre-prepared liquid A and pre-prepared liquid B are injected into the same sealed container at a volume ratio of 1:1 and mixed. The two react with each other in the sealed container to produce foam.

[0013] (4) The foam in the sealed container of step (3) is subjected to ultraviolet radiation to induce a radiation crosslinking reaction, thereby obtaining gel foam;

[0014] (5) Soak the gel foam obtained in step (4) in a mixed solution of glycerol and ethanol for more than 3 hours, and finally take it out and drain it, and dry it under normal pressure to obtain a porous gel foam material with high water absorption rate.

[0015] Preferably, in step (1), the molar ratio of acrylic acid to acrylamide is 1-6:1.

[0016] Preferably, the crosslinking agent in step (1) is polyethylene glycol diacrylate.

[0017] Preferably, the amount of crosslinking agent added in step (1) is 4-6% of the mass of acrylic acid and acrylamide.

[0018] Preferably, the photoinitiator in step (2) is 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0019] Preferably, in step (2), the amount of photoinitiator added is 0.2-2% of the volume percentage of the prepreg B.

[0020] A porous gel foam material with high water absorption rate is prepared by the above-described preparation method.

[0021] In the above-described embodiments of the present invention, cellulose nanofibers, with their small size, large specific surface area, high crystallinity, and abundance of free hydroxyl groups, have applications in areas such as increasing mechanical strength, hydrogen bonding cross-linking, and self-assembly. They can reinforce the host material, expanding the controllable range of mechanical properties and application areas. Cellulose nanofibers can reinforce the gel skeleton, providing superior support, which enables atmospheric pressure drying of the hydrogel. The gel foam, while maintaining its own properties, possesses a foam structure, giving it strong water absorption capabilities.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] (1) The preparation method of the present invention effectively reduces the preparation cost of gel foam material, consumes little energy, does not involve complex equipment, has a simple and easy process, and has a short synthesis preparation time (90-150s), and is expected to be mass-produced under normal pressure conditions.

[0024] (2) The gel foam material prepared by this invention has a large water absorption capacity and stable moisture absorption performance. The presence of cellulose nanofibers significantly improves the strength of the gel, ensuring that the pore structure does not collapse when the material is dried under normal pressure. Attached Figure Description

[0025] Figure 1 This is a physical image of the gel foam material prepared according to the present invention.

[0026] Figure 2 The images show a comparison of scanning electron microscope images of the gel foam material prepared in this invention.

[0027] Figure 3 This is a comparison image of the gel foam material prepared in this invention before and after modification under normal pressure drying.

[0028] Figure 4 This is a comparison chart of the mechanical properties of the foam materials of Example 2 and Comparative Example 2 at 25 °C. Detailed Implementation

[0029] The technical solution of the present invention will be further described in detail below through specific embodiments. Unless otherwise specified, the methods in the following embodiments are conventional methods in the art.

[0030] This invention mainly provides a method for preparing a porous gel foam material with high water absorption rate, which specifically includes the following steps:

[0031] (1) Acrylic acid, acrylamide, and methylcellulose are sequentially dispersed and dissolved in a cellulose nanofiber dispersion with a solid content of 0.5-2%; the total molar concentration of acrylic acid and acrylamide is 7-8 mol / L; finally, a crosslinking agent is added to the mixture and mixed evenly to obtain pre-prepared solution A; the mass of methylcellulose accounts for 0.1-0.3% of the total mass of pre-prepared solution A; wherein, the molar ratio of acrylic acid to acrylamide is 1-6:1; the crosslinking agent is polyethylene glycol diacrylate, and the amount added is 4-6% of the total mass of acrylic acid and acrylamide;

[0032] (2) Sodium bicarbonate is saturated and dissolved in a cellulose nanofiber dispersion with a solid content of 0.5-2%. Then, a photoinitiator is added to the mixed dispersion and mixed evenly to obtain pre-prepared solution B. The photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone, and the amount added is 0.2-2% of the volume of pre-prepared solution B.

[0033] (3) Using a dual-channel syringe, pre-prepared liquid A and pre-prepared liquid B are injected into the same sealed container at a volume ratio of 1:1 and mixed. The two react with each other in the sealed container to produce foam.

[0034] (4) The foam in the sealed container of step (3) is subjected to ultraviolet radiation to induce a radiation crosslinking reaction, thereby obtaining gel foam;

[0035] (5) Soak the gel foam obtained in step (4) in a mixed solution of glycerol and ethanol for more than 3 hours, and finally take it out and drain it, and dry it under normal pressure to obtain a porous gel foam material with high water absorption rate.

[0036] Example 1:

[0037] The specific preparation steps of a porous gel foam material with high water absorption rate are as follows:

[0038] (1) Dissolve 3.9g acrylic acid, 3.8g acrylamide and 0.05g methylcellulose in 10 mL of cellulose nanofiber dispersion, then add crosslinking agent polyethylene glycol diacrylate, the crosslinking agent accounts for 4% of the total mass of monomers, and mix evenly to obtain prepreg A;

[0039] (2) Dissolve NaHCO3 in 15 mL of cellulose nanofiber dispersion, then add 30 μL of photoinitiator, which is 2-hydroxy-2-methyl-1-phenyl-1-propanone, at a volume percentage of 0.2% of the pre-prepared solution B. Mix thoroughly to obtain pre-prepared solution B;

[0040] (3) Inject the pre-prepared solutions A and B into the sealed bag using a dual-channel syringe;

[0041] (4) The foam in the sealed bag was irradiated with a 200 W ultraviolet lamp at 30 °C for 120 s to complete the radiation crosslinking;

[0042] (5) The obtained gel foam is immersed in a mixed solution of glycerol and ethanol with a volume ratio of 10 / 90, and finally dried under normal pressure to obtain a porous gel foam material with high water absorption rate.

[0043] Example 2:

[0044] The specific preparation steps of a porous gel foam material with high water absorption rate are as follows:

[0045] (1) Dissolve 5.8g acrylic acid, 2.0g acrylamide and 0.05g methylcellulose in 10 mL of cellulose nanofiber dispersion, then add crosslinking agent polyethylene glycol diacrylate, the crosslinking agent accounts for 5% of the total mass of monomers, and mix evenly to obtain prepreg A;

[0046] (2) Dissolve NaHCO3 in 15 mL of cellulose nanofiber dispersion, then add 150 μL of photoinitiator, which is 2-hydroxy-2-methyl-1-phenyl-1-propanone, at a volume percentage of 1% of the pre-prepared solution B. Mix thoroughly to obtain pre-prepared solution B;

[0047] (3) Inject the pre-prepared solutions A and B into the sealed bag using a dual-channel syringe;

[0048] (4) The foam in the sealed bag was irradiated with a 200 W ultraviolet lamp at 30 °C for 120 s to complete the radiation crosslinking;

[0049] (5) The obtained gel foam is immersed in a mixed solution of glycerol and ethanol with a volume ratio of 10 / 90, and finally dried under normal pressure to obtain a porous gel foam material with high water absorption rate.

[0050] Example 3:

[0051] The specific preparation steps of a porous gel foam material with high water absorption rate are as follows:

[0052] (1) Dissolve 6.6g acrylic acid, 1.1g acrylamide and 0.05g methylcellulose in 9 mL of cellulose nanofiber dispersion, then add crosslinking agent polyethylene glycol diacrylate, the crosslinking agent accounts for 6% of the total mass of monomers, and mix evenly to obtain prepreg A;

[0053] (2) Dissolve NaHCO3 in 15 mL of cellulose nanofiber dispersion, then add 300 μL of photoinitiator, which is 2-hydroxy-2-methyl-1-phenyl-1-propanone, at a volume percentage of 2% of the pre-prepared solution B. Mix thoroughly to obtain pre-prepared solution B;

[0054] (3) Inject the pre-prepared solutions A and B into the sealed bag using a dual-channel syringe;

[0055] (4) The foam in the sealed bag was irradiated with a 200 W ultraviolet lamp at 30 °C for 120 s to complete the radiation crosslinking;

[0056] (5) The obtained gel foam is immersed in a mixed solution of glycerol and ethanol with a volume ratio of 10 / 90, and finally dried under normal pressure to obtain a porous gel foam material with high water absorption rate.

[0057] Example 4:

[0058] The specific preparation steps of a porous gel foam material with high water absorption rate are as follows:

[0059] (1) Dissolve 5.8g of acrylic acid, 2.0g of acrylamide and 0.03g of methylcellulose in 9 mL of cellulose nanofiber dispersion, then add crosslinking agent polyethylene glycol diacrylate, the crosslinking agent accounts for 5% of the total mass of monomers, and mix evenly to obtain prepreg A;

[0060] (2) Dissolve NaHCO3 in 15 mL of cellulose nanofiber dispersion, then add 75 μL of photoinitiator, which is 2-hydroxy-2-methyl-1-phenyl-1-propanone, at a volume percentage of 0.5% of the pre-prepared solution B. Mix thoroughly to obtain pre-prepared solution B;

[0061] (3) Inject the pre-prepared solutions A and B into the sealed bag using a dual-channel syringe;

[0062] (4) The foam in the sealed bag was irradiated with a 200 W ultraviolet lamp at 30 °C for 120 s to complete the radiation crosslinking;

[0063] (5) The obtained gel foam is immersed in a mixed solution of glycerol and ethanol with a volume ratio of 10 / 90, and finally dried under normal pressure to obtain a porous gel foam material with high water absorption rate.

[0064] Example 5:

[0065] The specific preparation steps of a porous gel foam material with high water absorption rate are as follows:

[0066] (1) Dissolve 5.8g of acrylic acid, 2.0g of acrylamide and 0.02g of methylcellulose in 9 mL of cellulose nanofiber dispersion, then add crosslinking agent polyethylene glycol diacrylate, the crosslinking agent accounts for 5% of the total mass of monomers, and mix evenly to obtain prepreg A;

[0067] (2) Dissolve NaHCO3 in 15 mL of cellulose nanofiber dispersion, then add 75 μL of photoinitiator, which is 2-hydroxy-2-methyl-1-phenyl-1-propanone, at a volume percentage of 0.5% of the pre-prepared solution B. Mix thoroughly to obtain pre-prepared solution B;

[0068] (3) Inject the pre-prepared solutions A and B into the sealed bag using a dual-channel syringe;

[0069] (4) The foam in the sealed bag was irradiated with a 200 W ultraviolet lamp at 30 °C for 120 s to complete the radiation crosslinking;

[0070] (5) The obtained gel foam is immersed in a mixed solution of glycerol and ethanol with a volume ratio of 10 / 90, and finally dried under normal pressure to obtain a porous gel foam material with high water absorption rate.

[0071] Comparative Example 1:

[0072] The preparation method of the material in this comparative example specifically includes the following steps:

[0073] (1) Dissolve 5.8g of acrylic acid, 2.0g of acrylamide and 0.05g of methylcellulose in 10 mL of deionized water, then add the crosslinking agent polyethylene glycol diacrylate, the crosslinking agent accounts for 5% of the total mass of monomers, and mix evenly to obtain prepreg A;

[0074] (2) Dissolve NaHCO3 in 15 mL of deionized water, then add 150 μL of photoinitiator, which is 2-hydroxy-2-methyl-1-phenyl-1-propanone, at a volume percentage of 1% of the pre-prepared solution B. Mix well to obtain pre-prepared solution B;

[0075] (3) Inject the pre-prepared solutions A and B into the sealed bag using a dual-channel syringe;

[0076] (4) The foam in the sealed bag was irradiated with a 200 W ultraviolet lamp at 30 °C for 120 s to complete the radiation crosslinking;

[0077] (5) The obtained gel foam is immersed in a mixed solution of glycerol and ethanol with a volume ratio of 10 / 90, and finally dried under normal pressure to obtain gel foam.

[0078] Comparative Example 2:

[0079] The preparation method of the material in this comparative example specifically includes the following steps:

[0080] (1) Dissolve 3.9g acrylic acid, 3.8g acrylamide and 0.05g methylcellulose in 10 mL of cellulose nanofiber dispersion, then add crosslinking agent polyethylene glycol diacrylate, the crosslinking agent accounts for 5% of the total mass of monomers, and mix evenly to obtain prepreg A;

[0081] (2) Dissolve NaHCO3 in 15 mL of cellulose nanofibers, then add 150 μL of photoinitiator, which is 2-hydroxy-2-methyl-1-phenyl-1-propanone, at a volume percentage of 1% of the pre-prepared solution B. Mix thoroughly to obtain pre-prepared solution B;

[0082] (3) Inject the pre-prepared solutions A and B into the sealed bag using a dual-channel syringe;

[0083] (4) The foam in the sealed bag was irradiated with a 200 W ultraviolet lamp at 30 °C for 120 s to complete the radiation crosslinking;

[0084] (5) Drying under normal pressure yields gel foam.

[0085] The water absorption properties of the gel foam of the present invention were tested, and the morphology after drying at normal pressure was compared with that of Comparative Example 1. The results are shown in the table below.

[0086] Comparison table of water absorption performance at 25℃:

[0087] Absorption time Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 0 1 1 1 1 1 1 1 1 min 14 11 10 15 13 12 10 2 min 26 29 21 27 25 16 14 3 min 36 39 31 38 36 21 22 4 min 42 48 40 44 46 30 25

[0088] The foam moisture content (R) in the table is calculated using the following formula:

[0089] ;

[0090] in:

[0091] M1 represents the mass of the foam gel after water absorption.

[0092] M0 represents the original mass of the foam gel.

[0093] Analysis of the data in the table above shows that the water absorption of the gel foam materials obtained in Examples 1, 2, and 3 is not significantly different, indicating that the materials obtained within the specified monomer concentration range have stable water absorption properties. Examples 2, 4, and 5 show that when the amount of methylcellulose added reaches a certain value, the gel foam can remain intact. Comparative Example 1, without the addition of cellulose nanofibers, has poor water absorption properties, indicating that cellulose nanofibers play a stabilizing role in the gel foam skeleton, ensuring that the pore structure of the gel foam remains good. The material obtained in Comparative Example 2, without soaking in glycerol ethanol, has poor water absorption properties, indicating that glycerol ethanol plays a stabilizing role in the pore structure of the gel foam during the atmospheric pressure drying process.

[0094] like Figure 2 The figure shows a comparison of mechanical properties at 25 ℃.

[0095] right Figure 4 Analysis showed that the gel foam materials obtained in Comparative Example 1 and Example 2 were compressed to 80% of their size at a compression rate of 50 μm / s. In Comparative Example 1, cellulose nanofibers were not added, water was used as the solvent, and other addition amounts were the same as in Example 2. The curve comparison clearly shows that Example 2 exhibits higher compressive strength and better flexibility; the cellulose nanofibers can reinforce the gel's framework, resulting in superior support.

[0096] As can be seen from the table above, the water absorption of the gel foam of the present invention is superior to that of the original foam products. Considering the moisture absorption and the state after drying, it can be concluded that the product can be dried under normal pressure and has excellent water absorption function. Figure 3 The gel foam of this invention has good strength and water absorption, and the raw materials are inexpensive, the equipment requirements are low, and the operation is simple, making it potential for mass production and commercialization.

[0097] It will be apparent to those skilled in the art that the above embodiments are not intended to be exhaustive or to limit the embodiments to the specific, precise forms disclosed. It will also be apparent to those skilled in the art that modifications, combinations, and variations can be made based on the above teachings.

Claims

1. A method of making a superabsorbent porous gel foam material, characterized by: The preparation method specifically comprises the following steps: (1) acrylic acid, acrylamide and methyl cellulose are sequentially dispersed and dissolved in a cellulose nanofiber dispersion liquid with a solid content of 0.5-2%; the total molar concentration of acrylic acid and acrylamide is 7-8 mol / L; finally, a crosslinking agent is added into the mixed dispersion liquid and uniformly mixed to obtain a pre-liquid A; the mass of methyl cellulose accounts for 0.1-0.3% of the total mass of the pre-liquid A; (2) sodium bicarbonate is saturatedly dissolved in a cellulose nanofiber dispersion liquid with a solid content of 0.5-2%, and then a photoinitiator is added into the mixed dispersion liquid and uniformly mixed to obtain a pre-liquid B; (3) the pre-liquid A and the pre-liquid B are injected into the same sealed container through a double-channel injector according to a volume ratio of 1:1, and the acid-base reaction occurs in the sealed container to generate foam; (4) the foam in the sealed container in step (3) is subjected to ultraviolet radiation treatment to perform radiation crosslinking reaction, and a gel foam is obtained; (5) the gel foam obtained in step (4) is soaked in a mixed solution of glycerol and ethanol for more than 3 h, and finally taken out and drained, and then dried at normal pressure to obtain a high-water-absorption porous gel foam material.

2. The method for preparing a high water absorption porous gel foam material according to claim 1, characterized in that: In step (1), the molar ratio of acrylic acid to acrylamide is 1-6:

1.

3. The method of claim 1 or 2, wherein the method further comprises the step of: a) adding a cross-linking agent to the mixture of step (b) to form a cross-linked porous gel foam material. In step (1), the crosslinking agent is polyethylene glycol diacrylate.

4. The method for preparing a high water absorption porous gel foam material according to claim 1, characterized in that: In step (1), the addition amount of the crosslinking agent is 4-6% of the total mass of acrylic acid and acrylamide.

5. The method for preparing a high water absorption porous gel foam material according to claim 1, characterized in that: In step (2), the photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone.

6. The method for preparing a high water absorption porous gel foam material according to claim 1, characterized in that: In step (2), the addition amount of the photoinitiator is 0.2-2% of the volume percentage of the pre-liquid B.

7. A superabsorbent porous gel foam material characterized by: The foam material is prepared by the preparation method in any one of claims 1-6.

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