Hydrogel surface modification method and anti-swelling hydrogel

Abstract

According to the hydrogel surface modification method and the anti-swelling hydrogel provided by the invention, the hydrophobic polymer is chemically grafted to the carboxyl-rich acrylic hydrogel by utilizing photocatalytic decarboxylation, and a hydrophobic modified layer is formed on the surface, so that the anti-swelling property and the stability of the structure and the property of the hydrogel are effectively improved. The acridine is used as a photocatalyst, carboxylic acid groups on the surface of the hydrogel are subjected to a decarboxylation reaction under ultraviolet irradiation, formed alkyl radicals react with hydrophobic acrylate polymers to generate strong covalent bonds, and the hydrophobic polymers are rapidly and stably anchored to the surface of the hydrogel. The hydrogel surface modification method provided by the invention can improve the swelling resistance of traditional acrylic acid hydrogel, and meanwhile, the hydrogel hydrophobic modification method provided by the invention does not depend on the carbon chain type and chain length of an acrylic ester hydrophobic polymer modifier, and has certain universality.

Description

Technical Field

[0001] The present invention relates to the field of hydrogel materials, and particularly to a method for surface modification of hydrogels and a swelling-resistant hydrogel. Background Art

[0002] Hydrogels are three-dimensional networks with hydrophilic properties that can absorb and retain a large amount of water. Polyacrylic acid hydrogel is a common synthetic polymer hydrogel, which has received extensive attention in many fields such as tissue engineering, drug release, wound dressings, cosmetics, smart devices, and adsorption due to its soft and water-rich characteristics. However, the open structure of the polyacrylic acid hydrogel network makes it extremely easy to absorb water and swell in water, seriously affecting its inherent properties. Therefore, it is crucial to construct a hydrogel with stronger swelling resistance.

[0003] To solve this problem, great efforts have been made in enhancing the swelling properties of polyacrylic acid hydrogels. One method is to copolymerize different monomers in the polyacrylic acid gel matrix, which can improve the swelling resistance of the hydrogel, but this method inevitably damages the inherent hydrophilic properties of the hydrogel matrix. Another method is to perform surface physical modification on the hydrogel. Silica particles can be physically doped onto the hydrogel surface to form a micro / nano rough structure and reduce the surface energy, thereby enhancing the hydrophobicity. However, the particles are prone to agglomeration and the binding force with the gel decreases, resulting in uneven hydrophobic modification effects and poor stability.

[0004] Performing chemical modification on the hydrogel surface can effectively improve the above problems. It can precisely regulate the surface properties of the hydrogel without affecting its inherent properties. At the same time, this method realizes the surface modification of the hydrogel through covalent bonds and has high stability. In the present invention, under mild conditions, decarboxylation modification of the polyacrylic acid hydrogel surface is achieved with ultraviolet light as a medium. A hydrophobic polymer is chemically grafted onto the carboxyl-rich polyacrylic acid hydrogel surface through covalent interaction to form a dense hydrophobic modification layer, effectively preventing water penetration between the gel matrix and the surrounding environment, improving the swelling resistance of the hydrogel and the stability of its structure and properties, thus completing the present invention. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for surface modification of hydrogels and a swelling-resistant hydrogel. By constructing a hydrophobic modification layer on the hydrogel surface, a protective barrier is provided for the hydrogel, effectively reducing the water absorption rate of the hydrogel, improving the swelling resistance performance of the hydrogel, and enhancing the stability of the hydrogel structure and properties.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A method for surface modification of a hydrogel, wherein the method includes chemically grafting a hydrophobic polymer chain on the surface of the hydrogel to construct a hydrophobic layer.

[0008] The described method for surface modification of hydrogel, wherein the method comprises the following steps:

[0009] a. Place the hydrogel at room temperature to remove the water on the surface of the hydrogel.

[0010] b. Dissolve the modifier in dichloromethane solution, add the catalyst after complete stirring, and continue stirring until completely dissolved.

[0011] c. Put the hydrogel treated in step a into the mixture obtained in step b, purge with nitrogen to remove oxygen, and seal. Then stir at room temperature for 30 min.

[0012] d. Under ultraviolet light irradiation, stir the sample obtained in step c at room temperature for reaction. After the reaction is completed, take out the hydrogel and rinse the hydrogel with dichloromethane solution to remove the catalyst and unreacted modifier.

[0013] The described method for surface modification of hydrogel, wherein in step a, the hydrogel is placed at room temperature for 3 h.

[0014] The described method for surface modification of hydrogel, wherein in step b, the modifier includes at least one of n-octyl acrylate, decyl acrylate, dodecyl acrylate, tetradecyl acrylate, hexadecyl acrylate, octadecyl acrylate, 2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctyl acrylate, and perfluorooctylethyl acrylate.

[0015] The described method for surface modification of hydrogel, wherein in step b, the concentration of the modifier is 0.005 - 0.045 mol / L.

[0016] The described method for surface modification of hydrogel, wherein in step b, the catalyst is acridine and the concentration of the catalyst is 0.001 - 0.004 mol / L.

[0017] The described method for surface modification of hydrogel, wherein in step c, the time for purging with nitrogen to remove oxygen is 3 - 5 min.

[0018] The described method for surface modification of hydrogel, wherein in step d, the wavelength of the ultraviolet light is 395 - 405 nm.

[0019] The described method for surface modification of hydrogel, wherein in step d, the modification time is 4 h.

[0020] A swelling-resistant hydrogel, wherein the hydrogel is treated by the method for surface modification of hydrogel described above. Description of the Drawings Figure 1XPS spectra of unmodified hydrogel PAA and perfluorooctylethyl acrylate modified hydrogel PAA-HFDA. Figure 2 Fourier transform infrared spectroscopy analysis of unmodified hydrogel PAA and perfluorooctylethyl acrylate modified hydrogel PAA-HFDA. Figure 3 Schematic diagrams of water droplet contact angles on the surfaces of unmodified hydrogel PAA (a), hydrogels PAA-HFDA (b), PAA-PFOA (c), PAA-DA (d), PAA-OA (e) modified with different hydrophobic polymers provided in the embodiments of the present invention. Figure 4 Comparison of swelling ratios of PAA hydrogel before and after modification after 12 h of immersion in water. Figure 5 Scanning electron micrograph of unmodified hydrogel PAA. Figure 6 Scanning electron micrograph of perfluorooctylethyl acrylate modified hydrogel PAA-HFDA. Figure 7 Cross-sectional scanning electron micrograph of perfluorooctylethyl acrylate modified hydrogel PAA-HFDA.

Claims

1. A method for surface modification of hydrogel, characterized in that, The method includes chemically grafting hydrophobic polymer chains on the surface of the hydrogel to construct a hydrophobic modification layer.

2. The hydrogel surface modification method according to claim 1, characterized in that, The method includes the following steps: a. Place the hydrogel at room temperature and remove the water on the surface of the hydrogel. b. Dissolve the modifier in dichloromethane solution, add the catalyst after complete stirring, and continue stirring until completely dissolved. c. Put the hydrogel treated in step a into the solution obtained in step b, purge with nitrogen to remove oxygen, seal, and then stir at room temperature for 30 min. d. Under ultraviolet light irradiation, stir the sample obtained in step c at room temperature for reaction. After the reaction is completed, take out the hydrogel and rinse the hydrogel with dichloromethane solution to remove the catalyst and unreacted modifier.

3. The hydrogel surface modification method according to claim 2, characterized in that, In step a, the hydrogel is placed at room temperature for 3 h.

4. The hydrogel surface modification method according to claim 2, wherein In step b, the modifier includes at least one of n-octyl acrylate, decyl acrylate, dodecyl acrylate, tetradecyl acrylate, hexadecyl acrylate, octadecyl acrylate, 1H,1H,2H,2H-perfluorooctyl acrylate, and perfluorooctylethyl acrylate.

5. The hydrogel surface modification method according to claim 4, characterized in that, In step b, the concentration of the modifier is 0.005 - 0.045 mol / L.

6. The hydrogel surface modification method according to claim 2, wherein In step b, the catalyst is acridine, and the concentration of the catalyst is 0.001 - 0.004 mol / L.

7. The hydrogel surface modification method according to claim 2, characterized in that, In step c, the time for purging with nitrogen to remove oxygen is 3 - 5 min.

8. The hydrogel surface modification method according to claim 2, wherein In step d, the wavelength of the ultraviolet light is 395 - 405 nm.

9. The hydrogel surface modification method according to claim 2, wherein In step d, the modification time is 4 h.

10. A swelling-resistant hydrogel, characterized in that, The hydrogel is treated by the hydrogel surface modification method according to any one of claims 1 - 9.

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