High-strength polyvinyl alcohol gel and preparation method thereof

Abstract

The invention relates to the technical field of polyvinyl alcohol, and discloses high-strength polyvinyl alcohol gel and a preparation method thereof.The preparation method comprises the steps that diethylenetriamine, trimellitic anhydride acyl chloride, N, N-dimethyl ethylenediamine and the like are subjected to a reaction, and a cross-linking agent containing a plurality of tertiary amine and carboxyl groups is obtained; and then carrying out quaternization cross-linking reaction on bromobutyl polyvinyl alcohol and a plurality of tertiary amine groups of the cross-linking agent to obtain the quaternary ammonium salt ionic bond cross-linked polyvinyl alcohol gel. Meanwhile, carboxyl in the cross-linking agent and hydroxyl of polyvinyl alcohol form hydrogen bond interaction to form a hydrogen bond cross-linked network, so that the double-network cross-linked polyvinyl alcohol gel is obtained, and the tensile strength, the water absorption rate and the antibacterial property of the gel are remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of polyvinyl alcohol, in particular to a high-strength polyvinyl alcohol gel and a preparation method thereof. Background Art

[0002] Polyvinyl alcohol is cheap, easy to obtain, non-toxic, pollution-free, biodegradable, and can be prepared into new hydrogel materials by freeze-thaw method. It is widely used in biomedical fields such as gel dressings and artificial cartilage. However, traditional polyvinyl alcohol gel materials have low mechanical strength and no antibacterial properties, which is not conducive to the practical application of polyvinyl alcohol in biomedical fields.

[0003] Constructing multiple network cross-linked structures in polyvinyl alcohol gel materials can improve the mechanical strength of gel materials. Patent CN106633111B discloses a method for preparing a high-strength polyvinyl alcohol-based double network hydrogel, using polyvinyl alcohol, acrylamide, acrylic acid, N,N-methylenebisacryl, etc. as raw materials to construct a double network polyvinyl alcohol-based hydrogel with a physical cross-linked network and a chemical cross-linked network, which has the advantages of high strength and good mechanical properties. However, the patent does not give the polyvinyl alcohol gel good antibacterial properties. Summary of the invention

[0004] The invention solves the problem that the polyvinyl alcohol hydrogel has low water absorption rate and strength and has no antibacterial property.

[0005] The technical solution of the present invention is: a method for preparing high-strength polyvinyl alcohol gel: Step A: Add polyvinyl alcohol and 4-bromobutyryl chloride to a reaction flask, stir and react at 55-70°C for 2-4h, add petroleum ether, filter, wash with water, and dry to obtain bromobutyl polyvinyl alcohol. The reaction formula is: .

[0006] Step B: Add N,N-dimethylformamide, bromobutyl polyvinyl alcohol and a crosslinking agent to a reaction bottle, stir at 100-130° C. for 24-48 hours, add water after cooling, filter, wash with dichloromethane and ethanol in turn, add the product to a dialysis bag, dialyze with distilled water, and dry to obtain a high-strength polyvinyl alcohol gel.

[0007] Furthermore, in step A, the mass of 4-bromobutyryl chloride is 2-6% of the mass of polyvinyl alcohol.

[0008] Furthermore, in step B, the mass of the cross-linking agent is 8-25% of the mass of the bromobutyl polyvinyl alcohol.

[0009] (1) Place the reaction bottle in an ice water bath, add tetrahydrofuran, diethylenetriamine, and trimellitic anhydride chloride (300-330% of the molar amount of diethylenetriamine), react for 24-36 hours, distill under reduced pressure, and wash with petroleum ether to obtain a crosslinker precursor. The reaction formula is: .

[0010] (2) Add N,N-dimethylformamide, precursor, and 300-390% of the molar amount of precursor N,N-dimethylethylenediamine to the reaction bottle, stir and react at room temperature for 4-6 hours, add water and ethyl acetate, shake and let stand to separate, distill the organic phase under reduced pressure, and recrystallize the product with ethanol to obtain a crosslinking agent. The reaction formula is as follows: .

[0011] The technical effect of the present invention is as follows: 4-bromobutyryl chloride is reacted with polyvinyl alcohol to obtain bromobutyl polyvinyl alcohol; diethylenetriamine, trimellitic anhydride chloride, N,N-dimethylethylenediamine and the like are reacted to obtain a crosslinking agent containing multiple tertiary amine and carboxyl groups. Then, the bromobutyl group of the polyvinyl alcohol is used to react with multiple tertiary amine groups of the crosslinking agent to generate quaternary ammonium salt groups to obtain ion-bonded crosslinked polyvinyl alcohol gel. At the same time, the carboxyl group in the crosslinking agent forms a hydrogen bond interaction with the hydroxyl group of the polyvinyl alcohol to form a hydrogen bond crosslinking network, thereby obtaining a double-network crosslinked polyvinyl alcohol gel, the tensile strength of which is significantly improved, and the polyvinyl alcohol gel contains a large amount of hydrophilic quaternary ammonium salt and carboxyl groups, which significantly enhances the hydrophilicity of the gel and improves the water absorption rate, and the quaternary ammonium salt group gives the gel excellent antibacterial properties, and exhibits a very high antibacterial zone diameter for bacteria such as Staphylococcus aureus. DETAILED DESCRIPTION

[0012] For ease of understanding of the present invention, preferred embodiments of the present invention are provided below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0013] The polyvinyl alcohol model of the present invention is PVA1788, which is from Xiamen Minghuiyang Chemical Co., Ltd.

[0014] Embodiment 1: (1) Place the reaction bottle in an ice water bath, add 35 mL of tetrahydrofuran, 4 mmol of diethylenetriamine, and 12 mmol of trimellitic anhydride chloride, react for 36 hours, distill under reduced pressure, and wash with petroleum ether to obtain a crosslinker precursor.

[0015] (2) Add 40 mL of N,N-dimethylformamide, 3 mmol of precursor, and 9 mmol of N,N-dimethylethylenediamine to the reaction bottle, stir and react at room temperature for 6 h, add water and ethyl acetate, shake and let stand to separate the layers, distill the organic phase under reduced pressure, and recrystallize the product with ethanol to obtain a cross-linking agent.

[0016] (3) Add 20 g of polyvinyl alcohol and 0.4 g of 4-bromobutyryl chloride to a reaction flask, stir and react at 60°C for 2 h, add petroleum ether, filter, wash with water, and dry to obtain bromobutyl polyvinyl alcohol.

[0017] (4) Add 300 mL of N,N-dimethylformamide, 20 g of bromobutyl polyvinyl alcohol, and 1.6 g of the cross-linking agent prepared in step (2) to the reaction bottle, stir at 100° C. for 36 h, add water after cooling, filter, wash with dichloromethane and ethanol in sequence, add the product to a dialysis bag, dialyze with distilled water, and dry to obtain a high-strength polyvinyl alcohol gel.

[0018] Embodiment 2: (1) Place the reaction bottle in an ice water bath, add 35 mL of tetrahydrofuran, 4 mmol of diethylenetriamine, and 13.2 mmol of trimellitic anhydride chloride, react for 24 h, distill under reduced pressure, and wash with petroleum ether to obtain a crosslinker precursor.

[0019] (2) Add 50 mL of N,N-dimethylformamide, 3 mmol of precursor, and 10.8 mmol of N,N-dimethylethylenediamine to the reaction bottle, stir and react at room temperature for 4 h, add water and ethyl acetate, shake and let stand to separate the layers, distill the organic phase under reduced pressure, and recrystallize the product with ethanol to obtain a cross-linking agent.

[0020] (3) Add 20 g of polyvinyl alcohol and 0.8 g of 4-bromobutyryl chloride to a reaction flask, stir and react at 55°C for 4 h, add petroleum ether, filter, wash with water, and dry to obtain bromobutyl polyvinyl alcohol.

[0021] (4) Add 400 mL of N,N-dimethylformamide, 20 g of bromobutyl polyvinyl alcohol, and 1.6 g of the cross-linking agent prepared in step (2) into the reaction bottle, stir at 100° C. for 48 h, add water after cooling, filter, wash with dichloromethane and ethanol in sequence, add the product to a dialysis bag, dialyze with distilled water, and dry to obtain a high-strength polyvinyl alcohol gel.

[0022] Embodiment 3: (1) Place the reaction bottle in an ice water bath, add 30 mL of tetrahydrofuran, 4 mmol of diethylenetriamine, and 12.6 mmol of trimellitic anhydride chloride, react for 24 h, distill under reduced pressure, and wash with petroleum ether to obtain a crosslinker precursor.

[0023] (2) Add 30 mL of N,N-dimethylformamide, 3 mmol of precursor, and 9 mmol of N,N-dimethylethylenediamine to the reaction bottle, stir and react at room temperature for 6 h, add water and ethyl acetate, shake and let stand to separate the layers, distill the organic phase under reduced pressure, and recrystallize the product with ethanol to obtain a cross-linking agent.

[0024] (3) Add 20 g of polyvinyl alcohol and 1.2 g of 4-bromobutyryl chloride to a reaction flask, stir and react at 70°C for 2 h, add petroleum ether, filter, wash with water, and dry to obtain bromobutyl polyvinyl alcohol.

[0025] (4) Add 400 mL of N,N-dimethylformamide, 20 g of bromobutyl polyvinyl alcohol, and 1.6 g of the cross-linking agent prepared in step (2) into the reaction bottle, stir at 110° C. for 48 h, add water after cooling, filter, wash with dichloromethane and ethanol in sequence, add the product to a dialysis bag, dialyze with distilled water, and dry to obtain a high-strength polyvinyl alcohol gel.

[0026] Embodiment 4: (1) Add 400 mL of N,N-dimethylformamide, 20 g of bromobutyl polyvinyl alcohol (prepared in Example 2), and 2.3 g of a cross-linking agent (prepared in Example 2) into a reaction bottle, stir at 100° C. for 48 h, add water after cooling, filter, wash with dichloromethane and ethanol in turn, add the product to a dialysis bag, dialyze with distilled water, and dry to obtain a high-strength polyvinyl alcohol gel.

[0027] Embodiment 5: (1) Add 400 mL of N,N-dimethylformamide, 20 g of bromobutyl polyvinyl alcohol (prepared in Example 2), and 4.1 g of a cross-linking agent (prepared in Example 2) into a reaction bottle, stir at 100° C. for 48 h, add water after cooling, filter, wash with dichloromethane and ethanol in turn, add the product to a dialysis bag, dialyze with distilled water, and dry to obtain a high-strength polyvinyl alcohol gel.

[0028] Embodiment 6: (1) Add 400 mL of N,N-dimethylformamide, 20 g of bromobutyl polyvinyl alcohol (prepared in Example 2), and 5 g of a cross-linking agent (prepared in Example 2) into a reaction bottle, stir at 100° C. for 48 h, add water after cooling, filter, wash with dichloromethane and ethanol in turn, add the product to a dialysis bag, dialyze with distilled water, and dry to obtain a high-strength polyvinyl alcohol gel.

[0029] Comparative Example 1 (1) Add 200 mL of water and 20 g of polyvinyl alcohol to a reaction bottle, heat to 95 °C, stir to dissolve, cool to 50 °C, let stand to degas, then pour into a mold, freeze at -30 °C for 18 h, thaw at 25 °C for 6 h, repeat thawing and freezing three times, dry to remove water, and obtain polyvinyl alcohol gel.

[0030] Comparative Example 2 (1) Add 300 mL of N,N-dimethylformamide, 20 g of bromobutyl polyvinyl alcohol, and 1.6 g of N,N,N',N'-tetramethyl-1,4-butanediamine to a reaction flask, stir at 100°C for 36 h, add water after cooling, filter, wash with dichloromethane and ethanol in turn, add the product to a dialysis bag, dialyze with distilled water, and dry to obtain polyvinyl alcohol gel.

[0031] Comparative Example 3 (1) Add 200 mL of water, 20 g of polyvinyl alcohol, and 1.6 g of a cross-linking agent to a reaction bottle, heat to 95 °C, stir to dissolve, cool to 50 °C, let stand to degas, then pour into a mold, freeze at -30 °C for 18 h, thaw at 25 °C for 6 h, repeat thawing and freezing three times, dry to remove water, and obtain polyvinyl alcohol gel.

[0032] Comparative Example 4 (1) Add 300 mL of N,N-dimethylformamide, 20 g of polyvinyl alcohol, and 1.6 g of a cross-linking agent to a reaction bottle, stir at 100 °C for 36 h, add water after cooling, filter, and wash with dichloromethane and ethanol in turn. Add the product to a dialysis bag, dialyze with distilled water, and dry to obtain a polyvinyl alcohol blend.

[0033] The polyvinyl alcohol in Comparative Example 4 does not contain butyl bromide and cannot react with the multiple tertiary amine groups of the cross-linking agent to form a quaternary ammonium cross-linking reaction. The polyvinyl alcohol can only interact with the carboxyl group of the cross-linking agent by hydrogen bonding, and has low binding force and poor stability. It is difficult to form a gel, and the obtained polyvinyl alcohol blend is a non-gel material.

[0034] The tensile strength of polyvinyl alcohol gel was tested by a universal testing machine at a strain rate of 10 mm / min. Five samples were tested in each group and the average value was taken.

[0035] Weigh the dried polyvinyl alcohol gel (m0), add it into distilled water, let it stand for 6 hours, take out the gel, absorb the excess water on the surface with filter paper, weigh it (m1), and calculate the water absorption rate W.

[0036] W=(m1-m0) / m0×100%。

[0037] The polyvinyl alcohol gel was pressed into a film and sterilized under ultraviolet light; then it was made into a circular sheet with a thickness of 1 mm and a diameter of 5 mm. Staphylococcus aureus, Escherichia coli, and Candida albicans were activated at 37°C for 24 hours and then diluted to 10 6 cfu / mL bacterial suspension. Pipette 0.1mL of bacterial suspension onto beef extract peptone medium, stick a circular sheet onto the surface of the medium, incubate at 37℃ for 24h in a constant temperature incubator, and measure the diameter of the inhibition zone. Test 3 samples per group and take the average value.

[0038] Table 1: Effect test After testing, comparative example 1 prepared polyvinyl alcohol gel by freeze-thaw method, and its tensile strength and water absorption rate were low, and it did not show the inhibition zone diameter and antibacterial performance against bacteria such as Staphylococcus aureus.

[0039] In Example 1-6, the bromobutyl group of polyvinyl alcohol is used to react with multiple tertiary amine groups of a cross-linking agent to produce a quaternary ammonium salt group to obtain an ionically cross-linked polyvinyl alcohol gel. At the same time, the carboxyl group in the cross-linking agent forms a hydrogen bond interaction with the hydroxyl group of polyvinyl alcohol to form a hydrogen bond cross-linking network, thereby obtaining a double-network cross-linked polyvinyl alcohol gel with significantly improved tensile strength. The polyvinyl alcohol gel contains a large amount of hydrophilic quaternary ammonium salt and carboxyl groups, which significantly enhances the hydrophilicity of the gel and improves the water absorption rate. The quaternary ammonium salt group gives the gel excellent antibacterial properties, and exhibits a very high inhibition zone diameter against bacteria such as Staphylococcus aureus.

[0040] Comparative Example 2 uses bromobutyl polyvinyl alcohol and N,N,N',N'-tetramethyl-1,4-butanediamine to carry out quaternary ammonium crosslinking reaction. The obtained polyvinyl alcohol gel also contains quaternary ammonium salt groups, and exhibits a higher inhibition zone diameter against bacteria such as Staphylococcus aureus, and has good antibacterial properties. At the same time, an ionic bond crosslinking network is formed, and the tensile strength and water absorption rate are higher than those of Comparative Example 1, but N,N,N',N'-tetramethyl-1,4-butanediamine does not contain a carboxyl group, has a low hydrophilicity, and cannot form a hydrogen bond crosslinking network with polyvinyl alcohol, resulting in a lower water absorption rate and tensile strength of the gel than those of each embodiment.

[0041] In Comparative Example 3, a gel was prepared using polyvinyl alcohol and a cross-linking agent by a freeze-thaw method. The carboxyl group contained in the cross-linking agent gave the gel better hydrophilicity and formed a hydrogen bond cross-linking network with the polyvinyl alcohol. The water absorption and tensile strength of the gel were higher than those of Comparative Example 1. However, polyvinyl alcohol could not form a quaternary ammonium salt ion cross-linking network with the cross-linking agent, resulting in the tensile strength and water absorption of the gel being lower than those of the various embodiments, and the gel did not exhibit an inhibition zone diameter and antibacterial properties against bacteria such as Staphylococcus aureus.

[0042] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing high-strength polyvinyl alcohol gel, characterized in that: The preparation method comprises the following steps: Step A, adding polyvinyl alcohol and 4-bromobutyryl chloride into a reaction bottle, stirring for reaction, adding petroleum ether, filtering, washing, and drying to obtain bromobutyl polyvinyl alcohol; Step B, adding N,N-dimethylformamide, bromobutyl polyvinyl alcohol, and a crosslinking agent into a reaction bottle, stirring for reaction, adding water after cooling, filtering and washing, adding the product into a dialysis bag, dialyzing, and drying to obtain a high-strength polyvinyl alcohol gel; The structural formula of the cross-linking agent is: ; The R1 group is , the R2 group is ; or the R1 group is , the R2 group is ; The R3 group is , the R4 group is ; or the R3 group is , the R4 group is ; The R5 group is , the R6 group is ; or the R5 group is , the R6 group is .

2. The method for preparing high-strength polyvinyl alcohol gel according to claim 1, characterized in that: The mass of 4-bromobutyryl chloride in step A is 2-6% of the mass of polyvinyl alcohol.

3. The method for preparing high-strength polyvinyl alcohol gel according to claim 1, characterized in that: The reaction in step A is carried out at 55-70° C. for 2-4 hours.

4. The method for preparing high-strength polyvinyl alcohol gel according to claim 1, characterized in that: The mass of the cross-linking agent in step B is 8-25% of the mass of the bromobutyl polyvinyl alcohol.

5. The method for preparing high-strength polyvinyl alcohol gel according to claim 1, characterized in that: The reaction in step B is carried out at 100-130° C. for 24-48 hours.

6. The method for preparing high-strength polyvinyl alcohol gel according to claim 1, characterized in that: The preparation method of the cross-linking agent comprises: (1) Place the reaction bottle in an ice water bath, add tetrahydrofuran, diethylenetriamine, and trimellitic anhydride chloride, react for 24-36 hours, distill under reduced pressure, and wash to obtain a crosslinker precursor; (2) Add N,N-dimethylformamide, precursor, and N,N-dimethylethylenediamine to the reaction bottle, stir and react at room temperature for 4-6 hours, add water and ethyl acetate, shake and let stand to separate the layers, separate the organic phase, distill under reduced pressure, and recrystallize to obtain the cross-linking agent.

7. The method for preparing high-strength polyvinyl alcohol gel according to claim 6, characterized in that: The molar amount of trimellitic anhydride chloride is 300-330% of the molar amount of diethylenetriamine.

8. The method for preparing high-strength polyvinyl alcohol gel according to claim 6, characterized in that: The molar amount of the N,N-dimethylethylenediamine is 300-390% of the molar amount of the precursor.

9. A high-strength polyvinyl alcohol gel obtained by the preparation method according to any one of claims 1 to 8.

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