A method for preparing K-carrageenan hydrogel with excellent mechanical properties by hydrothermal reaction

Abstract

The present invention provides a method for preparing a K-carrageenan hydrogel with excellent mechanical properties by hydrothermal reaction, comprising the following steps: Step 1: Dissolve K-carrageenan and MXene in a polyvinyl alcohol solution to obtain a mixed solution; Step 2: Transfer the mixed solution into a reaction kettle, set the environmental temperature of the reaction kettle to 100 °C, maintain for 20 minutes, take it out and cool it to room temperature to obtain a gel; Step 3: Immerse the gel in a borax solution to obtain a hydrogel. For the gel immersed in the borax solution, by controlling the immersion time, the dynamic non-covalent cross-linking between the hydroxyl groups of polyvinyl alcohol and borate anions can be realized, and the cross-linking density can be changed, thereby realizing the regulation of the mechanical properties of the hydrogel.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogel preparation, and particularly relates to a method for preparing K-carrageenan hydrogel with excellent mechanical properties by hydrothermal reaction. Background Art

[0002] Hydrogels have attracted the attention of many researchers due to their excellent biocompatibility and mechanical properties similar to those of biological tissues. Hydrogels with complex network structures and excellent functionality can be prepared by different initiation polymerization methods. However, hydrogels prepared by physical and biological initiation methods often have unsatisfactory mechanical properties. Compared with the former two types of hydrogels, hydrogels prepared by chemical methods have obvious advantages in terms of mechanical strength, but such hydrogels are usually limited by long polymerization times and toxic components (including residual initiators or cross-linking agents). Although the hydrogels prepared by the above methods have different advantages, their disadvantages are also very prominent, such as high energy consumption and complex operation. Therefore, it is crucial to find an efficient, green and environmentally friendly gel method to prepare hydrogels and avoid the overuse of initiators and cross-linking agents. Summary of the Invention

[0003] In view of the above deficiencies of the prior art, the present invention provides a method for preparing K-carrageenan hydrogel with excellent mechanical properties by hydrothermal reaction.

[0004] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0005] A method for preparing K-carrageenan hydrogel with excellent mechanical properties by hydrothermal reaction, comprising the following steps: Step 1: Dissolve K-carrageenan and MXene in a polyvinyl alcohol solution to obtain a mixed solution;

[0006] Step 2: Transfer the mixed solution into a reaction kettle, place the reaction kettle in an oven and heat it, set the environmental temperature of the oven to 100 °C, keep it for 20 minutes, take it out and cool it to room temperature to obtain a gel;

[0007] Step 3: Immerse the gel in a borax solution to obtain a hydrogel.

[0008] Preferably, in Step 1, the content of polyvinyl alcohol in the polyvinyl alcohol solution is 5 wt% - 10 wt%, and the mass ratio of K-carrageenan, MXene and the polyvinyl alcohol solution is 20:1:50 - 100.

[0009] Preferably, in Step 3, the mass concentration of the borax solution is 4%, and the borax solution submerges the gel; by controlling the immersion time, the cross-linking degree of the hydrogel can be changed, thereby controlling the mechanical properties of the hydrogel.

[0010] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0011] 1. This method is different from the previous gel methods and is a completely new polymerization method. The advantages of this method are simple operation, low energy consumption, and low environmental pollution.

[0012] 2. The borate ester bonds formed between borate ions and PVA hydroxyl groups can serve as cross-linking points. By changing the dosage, the mechanical properties of the hydrogel can be regulated, broadening the application of the hydrogel. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0014] Figure 1 It is a schematic diagram of the synthesis route of KC / PVA / MXene-B hydrogel;

[0015] Figure 2 It is the detailed process of forming borate ester bonds between the hydroxyl groups on the PVA chain and borax;

[0016] Figure 3 It is the tensile stress-strain curve of the influence of soaking in borax solution for different times (0 min, 20 min, 40 min, 60 min, and 120 min) on the mechanical properties of the hydrogel. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] In order to better understand the above-mentioned objects, features, and advantages of the present invention, the following further describes the present invention with reference to the drawings and embodiments. It should be noted that, without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0018] In the following description, many specific details are set forth to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the present invention is not limited by the specific embodiments disclosed in the following specification.

[0019] A method for hydrothermal reaction to prepare K-carrageenan hydrogel with excellent mechanical properties, which dissolves K-carrageenan and MXene in a polyvinyl alcohol solution to obtain a mixed solution; transfers the mixed solution into a reaction kettle, then places the reaction kettle in an oven for heating, sets the environmental temperature of the oven to 100 °C, maintains it for 20 minutes, takes it out and cools it to room temperature to obtain a gel; soaks the gel in a borax solution to obtain a hydrogel; wherein the cross-linking degree of the hydrogel is controlled by changing the soaking time of the gel in the boric acid solution, thereby controlling the mechanical properties of the hydrogel.

[0020] As Figure 1 , Figure 2 shown, the design principle in this application is as follows:

[0021] Under the action of the temperature rise in the hydrothermal reaction, the long chain of K-carrageenan is induced to unwind, and during the temperature drop process, the long chain of K-carrageenan recombines to form a helix again, realizing the transformation from sol to gel.

[0022] The gel soaked in the borax solution can achieve the dynamic non-covalent cross-linking of PVA hydroxyl groups and borate ions. The borate ions react with the hydroxyl groups on polyvinyl alcohol to form borate ester bonds. With the change of the soaking time, the cross-linking density can be changed to realize the regulation of the mechanical properties of the hydrogel.

[0023] Example 1, a method for preparing a K-carrageenan hydrogel with excellent mechanical properties by hydrothermal reaction, specifically includes the following steps: Prepare K-carrageenan, a 5% mass concentration polyvinyl alcohol solution and MXene according to a mass ratio of 20:50:1. Dissolve K-carrageenan and MXene in the polyvinyl alcohol solution, mix evenly, put the obtained mixed solution into a reaction kettle, then place the reaction kettle in an oven and heat it. Set the oven environment temperature to 100 °C and keep it for 20 minutes. After taking it out and cooling it to room temperature, a gel is obtained;

[0024] The steps for testing the tensile properties of the gel are as follows: Conduct a tensile test on an electronic universal material testing machine. The test sample used is a cylindrical sample with a diameter of 4 mm and a height of 40 mm, and the tensile rate is 100 mm / min.

[0025] As Figure 3 shown, the obtained test results are: the tensile strength is 40 Kpa, and the elongation at break is 59%.

[0026] Example 2, a method for preparing a K-carrageenan hydrogel with excellent mechanical properties by hydrothermal reaction, specifically includes the following steps: Prepare K-carrageenan, a 6% mass concentration polyvinyl alcohol solution and MXene according to a mass ratio of 20:50:1. Dissolve K-carrageenan and MXene in the polyvinyl alcohol solution, mix evenly, put the obtained mixed solution into a reaction kettle, then place the reaction kettle in an oven and heat it. Set the oven environment temperature to 100 °C and keep it for 20 minutes. After taking it out and cooling it to room temperature, a gel is obtained.

[0027] Soak the gel in a 4 wt% boric acid solution. The boric acid solution should cover the gel and soak it for 20 min to obtain a hydrogel.

[0028] The steps for testing the tensile properties of the hydrogel are as follows: A tensile test is carried out on an electronic universal material testing machine. The test sample used is a cylindrical sample with a diameter of 4 mm and a height of 40 mm, and the tensile rate is 100 mm / min.

[0029] As Figure 3 shown, the test results obtained are: a tensile strength of 124 Kpa and an elongation at break of 279%.

[0030] Example 3, a method for preparing a K-carrageenan hydrogel with excellent mechanical properties by hydrothermal reaction, specifically includes the following steps: Prepare K-carrageenan, a polyvinyl alcohol solution with a mass concentration of 8%, and MXene in a mass ratio of 20:70:1. Dissolve K-carrageenan and MXene in the polyvinyl alcohol solution and mix evenly. Pour the obtained mixed solution into a reaction kettle, then place the reaction kettle in an oven and heat it. Set the oven ambient temperature to 100 °C and keep it for 20 minutes. After taking it out, cool it to room temperature to obtain a hydrogel.

[0031] Soak the gel in a boric acid solution with a mass concentration of 4 wt%, and the boric acid solution should cover the gel. Soak it for 40 min to obtain a hydrogel.

[0032] The steps for testing the tensile properties of the hydrogel are as follows: A tensile test is carried out on an electronic universal material testing machine. The test sample used is a cylindrical sample with a diameter of 4 mm and a height of 40 mm, and the tensile rate is 100 mm / min.

[0033] As Figure 3 shown, the test results obtained are: a tensile strength of 118 Kpa and an elongation at break of 384%.

[0034] Example 4, a method for preparing a K-carrageenan hydrogel with excellent mechanical properties by hydrothermal reaction, specifically includes the following steps: Prepare K-carrageenan, a polyvinyl alcohol solution with a mass concentration of 5%, and MXene in a mass ratio of 20:80:1. Dissolve K-carrageenan and MXene in the polyvinyl alcohol solution and mix evenly. Pour the obtained mixed solution into a reaction kettle, then place the reaction kettle in an oven and heat it. Set the oven ambient temperature to 100 °C and keep it for 20 minutes. After taking it out, cool it to room temperature to obtain a gel.

[0035] Soak the gel in a boric acid solution with a mass concentration of 4 wt%, and the boric acid solution should cover the gel. Soak it for 60 min to obtain a hydrogel.

[0036] The steps for testing the tensile properties of the hydrogel are as follows: A tensile test is carried out on an electronic universal material testing machine. The test sample used is a cylindrical sample with a diameter of 4 mm and a height of 40 mm, and the tensile rate is 100 mm / min.

[0037] AsFigure 3 As shown, the obtained test results are: tensile strength of 115 Kpa and elongation at break of 568%.

[0038] Example 5: A method for preparing K-carrageenan hydrogel with excellent mechanical properties by hydrothermal reaction, specifically including the following steps: Prepare K-carrageenan, a polyvinyl alcohol solution with a mass concentration of 7%, and MXene in a mass ratio of 20:80:1. Dissolve K-carrageenan and MXene in the polyvinyl alcohol solution and mix evenly. Pour the obtained mixed solution into a reaction kettle, and then place the reaction kettle in an oven for heating. Set the environmental temperature of the oven to 100 °C and keep it for 20 minutes. After taking it out, cool it to room temperature to obtain a gel.

[0039] Soak the gel in a boric acid solution with a mass concentration of 4 wt%, and the boric acid solution should cover the gel. Soak for 120 min to obtain a hydrogel.

[0040] The steps for testing the tensile properties of the hydrogel are as follows: Conduct a tensile test on an electronic universal material testing machine. The test sample used is a cylindrical sample with a diameter of 4 mm and a height of 40 mm, and the tensile rate is 100 mm / min.

[0041] As Figure 3 shown, the obtained test results are: tensile strength of 77 Kpa and elongation at break of 604%.

[0042] It can be seen from Examples 1 to 5 that in Example 1, the gel (KC / PVA / MXene) was not soaked in the boric acid solution. By comparing Example 1 with Examples 2 to 5, it can be known that for the hydrogel formed after soaking in the boric acid solution, the tensile strength and tensile elongation of the hydrogel have a relatively high increase.

[0043] It can be seen from Examples 2 to 5 that as the soaking time increases, the tensile strength will decrease slightly, while the tensile elongation will increase significantly.

[0044] The above is only a preferred embodiment of the present invention, and it does not limit the present invention in other forms. Any person skilled in the relevant art may use the disclosed technical content to make changes or modifications into equivalent embodiments with equivalent changes and apply them to other fields. However, as long as it does not depart from the technical solution content of the present invention, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing κ-carrageenan hydrogel with excellent mechanical properties by hydrothermal reaction, characterized in that, It includes the following steps: Step 1: Dissolve K-carrageenan and MXene in a polyvinyl alcohol solution to obtain a mixed solution; Step 2: Transfer the mixed solution into a reaction kettle, place the reaction kettle in an oven for heating, set the environmental temperature of the oven at 100 °C, keep it for 20 minutes, take it out and cool it to room temperature to obtain a gel; Step 3: Immerse the gel in a borax solution to obtain a hydrogel; In Step 1, the content of polyvinyl alcohol in the polyvinyl alcohol solution is 5 wt% - 10 wt%, and the mass ratio of K-carrageenan, MXene and the polyvinyl alcohol solution is 20:1:50 - 100; In Step 3, the mass concentration of the borax solution is 4%, and the borax solution submerges the gel. In Step 3, change the tensile strength or tensile elongation rate by changing the immersion time of the gel in the borax solution.

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