A method for preparing a polyvinyl alcohol sponge-like gel

Abstract

The application discloses a preparation method of polyvinyl alcohol sponge-like gel and belongs to the technical field of high polymer gel preparation. The polyvinyl alcohol solution is obtained by heating and dissolving, then small-molecule polyhydric alcohol, inorganic salt with salt-dissolving effect and inorganic salt with salting-out effect are sequentially added into the polyvinyl alcohol solution, the polyvinyl alcohol composite emulsion is obtained by stirring and mixing, the emulsion is placed and matured at normal temperature to obtain the sponge-like gel with open hole structure, the gel has extremely fast liquid absorption capacity and obvious negative pressure drainage effect, and can be applied to the fields of biological medicine and the like. Meanwhile, the polyvinyl alcohol sponge-like gel can still maintain the shape after repeatedly losing water and rehydrating.

Description

Technical Field

[0001] This invention belongs to the field of polymer gel preparation technology, specifically relating to a method for preparing polyvinyl alcohol sponge-like gel. Background Technology

[0002] Polyvinyl alcohol (PVA) is a water-soluble polymer with microbial biodegradability and is commonly used in biomedical materials. PVA sponges can be used as negative pressure dressings for surgical wound drainage. Currently, publicly available methods for preparing PVA sponges include: pore-forming agent filling, chemical foaming, mechanical stirring, and combinations of these methods. The pore-forming agent filling method uses starch as a pore-forming agent, along with a cross-linking agent. After cross-linking and curing, the starch pore-forming agent is removed from the sponge to obtain a porous PVA sponge. However, this method faces significant environmental pressures, requiring large amounts of water to wash away the starch, resulting in high water consumption and manufacturing costs. The chemical foaming method involves adding substances that can produce gases such as carbon dioxide or nitrogen through a chemical reaction during production. Under the homogenizing and stabilizing effect of surfactants, the foam is then cured to obtain PVA sponges. The mechanical stirring foaming method involves adding surfactants to a PVA solution, generating bubbles under high-speed stirring, and then adding a cross-linking agent for curing to obtain PVA sponges. All these methods require the use of aldehyde cross-linking agents and the addition of acids for catalytic cross-linking. Therefore, it is necessary to consider both the conditions for the acetal reaction and the process conditions for foaming and molding. This places high demands on the process. Furthermore, the addition of acids and aldehydes can also compromise the biocompatibility of polyvinyl alcohol.

[0003] To address the aforementioned problems, Chinese patent CN 103554801A discloses a modified polyvinyl alcohol (PVA) sponge and its preparation method. The sponge preparation method includes: adding 80-150 parts by weight of PVA to 600-1800 parts by weight of water and stirring, then heating to 60℃-98℃ to form a stable solution; adding 20-200 parts by weight of starch and 10-100 parts by weight of hexamethylenetetramine to the stable solution to form a mixed solution; adding 10-400 parts by weight of sulfuric acid or hydrochloric acid to the mixed solution, stirring evenly, and heating to 50-85℃ for curing for 8-20 hours; cooling, demolding, and washing to obtain the PVA sponge. This method solves the problems of odor, inconvenience for workers, and low production efficiency caused by the use of formaldehyde in various stages of the PVA sponge production process, and improves the product's wetting rate and increases the softness of the dried product. The PVA solution can also be freeze-thawed or chemically cross-linked to obtain PVA gel, which can then be freeze-dried or supercritical dried to obtain the PVA sponge. However, due to limitations of methods such as freeze-drying and supercritical drying, this method is difficult to industrialize for polyvinyl alcohol (PVA) sponge production. For example, Chinese patent CN 104045852A discloses a method for preparing a PVA sponge dressing, which fully utilizes ultraviolet curing and freeze-thaw technology to form a three-dimensional network structure of PVA sponge dressing combining chemical and physical cross-linking. The PVA sponge dressing prepared by this method has good biocompatibility and wet strength, while also being soft, conforming well to wound surfaces, and having good adhesion, making it widely applicable for wound drainage. Chinese patent CN 115368625A discloses a method for preparing aramid-assisted PVA aerogel. The preparation method includes: providing a composite dispersion containing PVA, aramid nanofibers, and an organic solvent; using this as a precursor to contact water to achieve a sol-gel transition, obtaining an aramid-assisted PVA hydrogel; then, with or without solvent replacement, drying to obtain an aramid-assisted PVA aerogel. However, this method uses organic solvents such as dimethyl sulfoxide (DMSO) in its preparation process.

[0004] To address the shortcomings of existing technologies, this invention presents a method for preparing polyvinyl alcohol (PVA) sponge-like gel. This method utilizes the synergistic effect of the protective properties of small organic molecule polyols and the salting-out effect of inorganic salts to prepare a PVA sponge-like gel that can be molded at room temperature and pressure. This method is simple, easy to implement, and low in cost, possessing strong industrialization potential. Furthermore, no toxic chemical reagents are introduced during the preparation process. The resulting PVA sponge-like gel exhibits a distinct open-pore structure, high biocompatibility, strong liquid absorption capacity, and significant negative pressure drainage effect. It can also withstand repeated dehydration and rehydration. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing polyvinyl alcohol (PVA) sponge-like gel. Through the synergistic effect of the organic small-molecule polyol and the salting-out effect of the inorganic salt, a PVA sponge is prepared by curing at room temperature. This PVA sponge has a distinct open-pore structure, enabling rapid water absorption and dehydration.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A polyvinyl alcohol sponge-like gel, the preparation method of which includes the following steps:

[0008] (1) Under heating conditions, polyvinyl alcohol is dissolved in deionized water to prepare a polyvinyl alcohol solution;

[0009] (2) Add small molecule polyol, inorganic salt with salt-dissolving effect and inorganic salt with salt-out effect to polyvinyl alcohol solution in sequence, and stir to mix well to obtain polyvinyl alcohol composite emulsion;

[0010] (3) The obtained polyvinyl alcohol composite emulsion is poured into a mold and sealed and aged in an environment of 0~50 ℃ for 1~10 hours to obtain the polyvinyl alcohol sponge gel.

[0011] Further, the heating temperature in step 1) is 80~100 ℃.

[0012] Furthermore, the polyvinyl alcohol used in step 1) can be one or more of the grades 1788, 1799, 2088, 2099, 2688, and 2699.

[0013] Further, the concentration of the polyvinyl alcohol solution obtained in step 1) is 1~20 wt%.

[0014] Further, in step 2), the amount of the small molecule polyol used is 50 wt% to 300 wt% of the amount of polyvinyl alcohol used; the small molecule polyol is selected from one or more of ethylene glycol, glycerol, sorbitol, polyethylene glycol 200, polyethylene glycol 400, polyethylene glycol 600, etc.

[0015] Furthermore, the amount of the inorganic salt with salt-dissolving effect is 10 wt% to 100 wt% of the amount of polyvinyl alcohol; the inorganic salt with salt-dissolving effect is selected from one or more of lithium chloride, calcium chloride, magnesium chloride, zinc chloride, calcium nitrate, zinc nitrate, and magnesium nitrate.

[0016] Furthermore, the amount of the inorganic salt with salting-out effect is 50 wt% to 200 wt% of the amount of polyvinyl alcohol; the inorganic salt with salting-out effect is selected from one or more of sodium chloride, sodium carbonate, sodium sulfate, and sodium citrate.

[0017] The aforementioned polyvinyl alcohol sponge-like gel has a distinct open-pore structure, high biocompatibility, strong liquid absorption capacity, and significant negative pressure drainage effect. It can also maintain its shape after repeated dehydration and rehydration, and can be used as a medical sponge or in other liquid absorption applications.

[0018] The significant advantages of this invention are:

[0019] (1) The preparation method of polyvinyl alcohol sponge gel in this invention is simple; the obtained polyvinyl alcohol sponge has obvious open-pore structure, which can achieve rapid water absorption and dehydration, and can be repeated.

[0020] (2) The polyvinyl alcohol sponge prepared by the present invention can be used as a water-absorbing sponge in household kitchens and bathrooms, or in the biomedical field, such as a surgical blood-absorbing sponge. Attached Figure Description

[0021] Figure 1 This is a sample image of the polyvinyl alcohol sponge gel prepared in Example 1.

[0022] Figure 2 The image shows the microstructure of the polyvinyl alcohol sponge gel prepared in Example 1. As can be seen from the image, the obtained polyvinyl alcohol sponge gel has a distinct open-pore structure.

[0023] Figure 3 The image shows a comparison of the state of the polyvinyl alcohol sponge gel prepared in Example 1 (left) and the gel after drying at 60 °C for 10 h (right). The dried gel can be restored to its sponge-like state by soaking it in water for 1 minute.

[0024] Figure 4 The density and porosity values ​​of the polyvinyl alcohol sponge gel prepared in Example 1 (left) and the gel after drying at 60 °C for 10 h (right).

[0025] Figure 5 The figure shows the adsorption effect of the polyvinyl alcohol sponge gel prepared in Example 1 on different liquids. As can be seen from the figure, the obtained polyvinyl alcohol sponge gel has good adsorption performance for water. Detailed Implementation

[0026] A polyvinyl alcohol sponge-like gel, the preparation method of which includes the following steps:

[0027] (1) Dissolve polyvinyl alcohol in deionized water at 80~100 ℃ to prepare a 1~20 wt% polyvinyl alcohol solution;

[0028] (2) Add 50 wt%~300 wt% of small molecule polyol, 10 wt%~100 wt% of inorganic salt with salt-dissolving effect, and 50 wt%~200 wt% of inorganic salt with salting-out effect to polyvinyl alcohol solution in sequence, and stir to obtain polyvinyl alcohol composite emulsion.

[0029] (3) The obtained polyvinyl alcohol composite emulsion is poured into a mold and sealed and aged in an environment of 0~50 ℃ for 1~10 hours to obtain the polyvinyl alcohol sponge gel.

[0030] The polyvinyl alcohol used can be one or more of the grades 1788, 1799, 2088, 2099, 2688, and 2699. The small molecule polyol is selected from one or more of ethylene glycol, glycerol, sorbitol, polyethylene glycol 200, polyethylene glycol 400, and polyethylene glycol 600. The inorganic salt with salt-dissolving effect is selected from one or more of lithium chloride, calcium chloride, magnesium chloride, zinc chloride, calcium nitrate, zinc nitrate, and magnesium nitrate. The inorganic salt with salting-out effect is selected from one or more of sodium chloride, sodium carbonate, sodium sulfate, and sodium citrate.

[0031] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.

[0032] Example 1

[0033] Take 1 g of polyvinyl alcohol 1799 and add it to 6 mL of deionized water. Dissolve it by heating in a water bath at 95 °C to obtain a polyvinyl alcohol solution. Add 2 g of ethylene glycol, 0.2 g of magnesium chloride and 3 g of sodium sulfate to the polyvinyl alcohol solution to obtain a uniform composite emulsion. Pour the composite emulsion into a mold and seal it. Let it mature at 20 °C for 1 h to obtain a polyvinyl alcohol sponge gel.

[0034] Example 2

[0035] Take 1 g of polyvinyl alcohol 1799 and add it to 6 mL of deionized water. Dissolve it by heating in a water bath at 95 °C to obtain a polyvinyl alcohol solution. Add 2 g of glycerol, 0.2 g of calcium chloride and 3 g of sodium citrate to the polyvinyl alcohol solution to obtain a uniform composite emulsion. Pour the composite emulsion into a mold and seal it. Let it mature at 30 °C for 2 h to obtain a polyvinyl alcohol sponge gel.

[0036] Example 3

[0037] Take 1 g of polyvinyl alcohol 2099 and add it to 6 mL of deionized water. Dissolve it by heating in a water bath at 95 °C to obtain a polyvinyl alcohol solution. Add 2 g of polyethylene glycol 200, 0.2 g of lithium chloride and 3 g of sodium chloride to the polyvinyl alcohol solution to obtain a uniform composite emulsion. Pour the composite emulsion into a mold and seal it. Let it mature at 30 °C for 2 h to obtain a polyvinyl alcohol sponge gel.

[0038] Example 4

[0039] Take 1 g of polyvinyl alcohol 2699 and add it to 7 mL of deionized water. Dissolve it by heating in a water bath at 95 °C to obtain a polyvinyl alcohol solution. Add 2 g of polyethylene glycol 200, 0.2 g of lithium chloride and 3 g of sodium chloride to the polyvinyl alcohol solution to obtain a uniform composite emulsion. Pour the composite emulsion into a mold and seal it. Let it mature at 30 °C for 2 h to obtain a polyvinyl alcohol sponge gel.

[0040] Example 5

[0041] Take 1 g of polyvinyl alcohol 2688 and add it to 7 mL of deionized water. Dissolve it by heating in a water bath at 95 °C to obtain a polyvinyl alcohol solution. Add 2 g of polyethylene glycol 400, 0.2 g of zinc chloride and 3 g of sodium chloride to the polyvinyl alcohol solution to obtain a uniform composite emulsion. Pour the composite emulsion into a mold and seal it. Let it mature at 30 °C for 2 h to obtain a polyvinyl alcohol sponge gel.

[0042] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for preparing a polyvinyl alcohol sponge-like gel, characterized in that, Includes the following steps: (1) Under heating conditions, polyvinyl alcohol is dissolved in deionized water to prepare a polyvinyl alcohol solution; (2) Add small molecule polyol, inorganic salt with salt-dissolving effect and inorganic salt with salt-out effect to polyvinyl alcohol solution in sequence, and stir to mix well to obtain polyvinyl alcohol composite emulsion; (3) The obtained polyvinyl alcohol composite emulsion is poured into a mold and sealed and cured in an environment of 0~50 ℃ for 1~10 hours to obtain the polyvinyl alcohol sponge gel; Step 2) The amount of the small molecule polyol used is 50 wt% to 300 wt% of the amount of polyvinyl alcohol used; the small molecule polyol is selected from one or more of ethylene glycol, glycerol, sorbitol, polyethylene glycol 200, polyethylene glycol 400, and polyethylene glycol 600; The amount of the inorganic salt with salt-dissolving effect is 10 wt% to 100 wt% of the amount of polyvinyl alcohol; the inorganic salt with salt-dissolving effect is selected from one or more of lithium chloride, calcium chloride, magnesium chloride, zinc chloride, calcium nitrate, zinc nitrate, and magnesium nitrate. The amount of the inorganic salt with salting-out effect is 50 wt% to 200 wt% of the amount of polyvinyl alcohol; the inorganic salt with salting-out effect is selected from one or more of sodium chloride, sodium carbonate, sodium sulfate, and sodium citrate.

2. The method for preparing a polyvinyl alcohol sponge-like gel according to claim 1, characterized in that: The heating temperature in step 1) is 80~100 ℃.

3. The method for preparing a polyvinyl alcohol sponge-like gel according to claim 1, characterized in that: The concentration of the polyvinyl alcohol solution obtained in step 1) is 1~20 wt%.

4. A polyvinyl alcohol sponge-like gel prepared by the method according to any one of claims 1 to 3.

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