Preparation method of reusable high-adhesion lignin hydrogel coating

Abstract

The present invention discloses a method for preparing a reusable high-adhesion lignin hydrogel coating, specifically: a hydrophilic polymer monomer, an electrolyte monomer and water are mixed, a hydrophilic polymer solution is formed by solution polymerization, and the mixture is dried to obtain a hydrophilic polymer; a hydrophilic polymer, a hydrophobic lignin and a solvent are mixed, and after sufficient stirring, hyaluronic acid is added and mixed to obtain a coating; the obtained coating is evenly applied on a substrate, the solvent is completely dried, and then the substrate covered with the lignin-based coating is immersed in water to swell the dry coating. The present invention utilizes the hydrophobic properties of lignin to prepare a lignin-based hydrogel coating that is physically adhered to a substrate. The coating has the advantages of high adhesion to the surface of a variety of substrates, convenient brushing, easy to wash off, and reusable.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogel material preparation, and particularly relates to a method for preparing a reusable high-adhesion lignin hydrogel coating. Background Art

[0002] Hydrogel is a functional polymer material with a three-dimensional network structure that contains water but is insoluble in water. Due to its water-containing properties, it is commonly used in agriculture, industry, food, biomedicine, materials and other fields. The substrate of the hydrogel coating combines the superior properties of the substrate itself (such as strength, stiffness and toughness) with the superior properties of the hydrogel (such as hydrophilicity, lubricity, biocompatibility and drug release). Therefore, hydrogel coatings have unique application advantages in improving the surface lubricity of medical catheters and medical guidewires, and imparting them with drug delivery and sensing properties. At the same time, the hydrophilic and oleophobic properties of the hydrogel coating give it excellent anti-fouling properties in aqueous or physiological environments.

[0003] Most of the current methods for preparing hydrogel coatings require complex processing of the hydrogel or substrate; for example, mechanical interlocking requires some specific microstructures, and the formation of these microstructures is relatively complex and difficult to achieve. Interfacial interpenetration can only be used on soft and permeable substrates, and usually requires the use of multiple initiators. Covalent anchoring requires specific treatment of the hydrogel and substrate to ensure the presence of specific covalent bonding groups between the hydrogel and the substrate. In addition, in the preparation of hydrogel coatings, in situ polymerization or cross-linking is required on the surface of the substrate. In addition, due to the introduction of chemical cross-linking, hydrogel coatings often have the problem of difficulty in removing the cross-linking agent after use. Summary of the Invention

[0004] The object of the present invention is to provide a method for preparing a reusable high-adhesion lignin hydrogel coating, which has high adhesion, is easy to wash off, and can be reused.

[0005] The technical solution adopted by the present invention is a method for preparing a reusable high-adhesion lignin hydrogel coating, which is specifically implemented according to the following steps:

[0006] Step 1: mixing a hydrophilic polymer monomer, an electrolyte monomer and water to form a hydrophilic polymer solution through solution polymerization, and drying to obtain a hydrophilic polymer;

[0007] Step 2: mixing a hydrophilic polymer, hydrophobic lignin, and a solvent, stirring thoroughly, adding hyaluronic acid, and mixing evenly to obtain a coating;

[0008] Step 3: evenly apply the prepared coating on the substrate, allow the solvent to completely dry, and then immerse the substrate covered with the lignin-based coating in water to allow the dry coating to swell, thereby obtaining the lignin-based hydrogel coating.

[0009] The present invention is also characterized in that:

[0010] In step 1, the hydrophilic polymer monomer is any one of N,N-dimethylacrylamide, methacrylamide, methacrylic acid, and N-isopropylacrylamide.

[0011] In step 1, the electrolyte monomer is any one of 1-vinyl-imidazolium bromide, 1-ethyl-3-methylimidazolium bromide, 1-propyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium bromide, 1-pentyl-3-methylimidazolium bromide, 1-hexyl-3-methylimidazolium bromide, 3-(methacrylamido)propyltrimethylammonium chloride, (3-acrylamidopropyl)trimethylammonium chloride, acryloyloxyethyltrimethylammonium chloride, sodium p-phenylenesulfonate, and sodium 2-acrylamido-2-methyl-1-propanesulfonate.

[0012] In step 1, the mass ratio of the hydrophilic polymer monomer to the electrolyte monomer is 1:0.01-1; the polymerization temperature is 1°C-95°C, and the polymerization time is 1-48 hours; the drying temperature is 0°C-100°C, and the drying time is 5-48 hours.

[0013] In step 2, the hydrophobic lignin is any one of acetic acid lignin, sulfate lignin, dioxane lignin, formic acid lignin, acetylated modified lignin, and alkylene oxide modified lignin; the solvent is any one of N,N-dimethylformamide, acetone, pyridine, N,N-dimethyl sulfoxide, dioxane, and ethyl acetate; the mass ratio of the hydrophobic lignin to the hydrophilic polymer is 2:1-3, and the amount of hyaluronic acid added is 0.1-2% of the total amount of the hydrophobic lignin and the hydrophilic polymer.

[0014] In step 3, the solvent drying temperature is -20°C to 50°C; the soaking temperature is 0°C to 50°C, and the soaking time is 24 to 72 hours.

[0015] In step 3, the substrate is any one of a wood substrate, a metal substrate, a glass substrate, a silicone substrate, and a polytetrafluoroethylene substrate.

[0016] The beneficial effects of the present invention are as follows: by dissolving lignin and a hydrophilic polymer in a co-solvent to form a coating, during the drying process of the coating on the substrate surface, the lignin and hydrophilic polymer self-assemble to form phase-separated regions with an interpenetrating structure. The hydrophilic polymer-dense regions can absorb water and swell, while the lignin-dense regions act to cross-link the hydrophilic polymer and prevent water from entering the interface between the gel and the substrate. Through the coating-drying-swelling method, a hydrogel coating with strong adhesion to the substrate is produced. In addition, because the hydrogel coating does not involve any chemical crosslinking, it can be easily washed off with a solvent and recovered. The hydrogel coating also has properties such as UV resistance and low friction. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the peeling energy result of the lignin hydrogel coating after the 90° peeling test;

[0018] Figure 2 1 is a graph showing the test results of the friction coefficient of the lignin hydrogel coating of Examples 1-4 against metal aluminum;

[0019] Figure 3 Schematic diagram of the experiment of testing the sliding friction resistance of a 316 stainless steel rod coated with a lignin hydrogel coating and a 316 stainless steel rod without a coating against a curved silicone tube in Example 6;

[0020] Figure 4 This is a graph showing the frictional resistance-displacement curves of a 316 stainless steel rod coated with a lignin hydrogel coating and an uncoated stainless steel rod against the inner wall of a curved silicone tube in Example 6;

[0021] Figure 5 These are sample photographs of the lignin hydrogel coatings of Examples 1-7. DETAILED DESCRIPTION

[0022] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] The method for preparing the reusable high-adhesion lignin hydrogel coating of the present invention is specifically implemented according to the following steps:

[0024] Step 1: mixing a hydrophilic polymer monomer, an electrolyte monomer and water to form a hydrophilic polymer solution through solution polymerization, and drying to obtain a hydrophilic polymer;

[0025] The hydrophilic polymer monomer is any one of N,N-dimethylacrylamide, methacrylamide, methacrylic acid, and N-isopropylacrylamide;

[0026] The electrolyte monomer is any one of 1-vinyl-imidazolium bromide, 1-ethyl-3-methylimidazolium bromide, 1-propyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium bromide, 1-pentyl-3-methylimidazolium bromide, 1-hexyl-3-methylimidazolium bromide, 3-(methacrylamido)propyltrimethylammonium chloride, (3-acrylamidopropyl)trimethylammonium chloride, acryloyloxyethyltrimethylammonium chloride, sodium p-phenylenesulfonate, and sodium 2-acrylamido-2-methyl-1-propanesulfonate;

[0027] The mass ratio of the hydrophilic polymer monomer to the electrolyte monomer is 1:0.01-1;

[0028] The polymerization temperature is 1°C to 95°C, and the polymerization time is 1 to 48 hours;

[0029] The drying temperature is 0℃~100℃ and the drying time is 5~48h;

[0030] Step 2: mixing a hydrophilic polymer, hydrophobic lignin, and a solvent, stirring thoroughly, adding hyaluronic acid, and mixing evenly to obtain a coating;

[0031] The hydrophobic lignin is any one of acetic acid lignin, sulfate lignin, dioxane lignin, formic acid lignin, acetylated modified lignin, and alkylene oxide modified lignin;

[0032] The solvent is any one of N,N-dimethylformamide, acetone, pyridine, N,N-dimethyl sulfoxide, dioxane, and ethyl acetate;

[0033] The mass ratio of hydrophobic lignin to hydrophilic polymer is 2:1-3, the added amount of hyaluronic acid is 0.1-2% of the total amount of hydrophobic lignin and hydrophilic polymer; the solid content of the coating is 1%-30%.

[0034] Step 3: evenly apply the prepared coating on the substrate, allow the solvent to completely dry, and then immerse the substrate covered with the lignin-based coating in water to allow the dry coating to swell, thereby obtaining the lignin-based hydrogel coating.

[0035] The solvent drying temperature is -20℃~50℃; the soaking temperature is 0℃~50℃, and the soaking time is 24~72h;

[0036] The substrate is any one of a wood substrate, a metal substrate, a glass substrate, a silicone substrate, and a polytetrafluoroethylene substrate;

[0037] The coating can be applied by brushing, spraying, roller coating, dipping, shower coating, or spin coating.

[0038] This invention utilizes the hydrophobic properties of lignin to create a lignin-based hydrogel coating that physically bonds to a substrate. This coating exhibits high adhesion to a variety of substrate surfaces, is easy to apply, easily washable, and reusable. Furthermore, the hydrogel coating exhibits high bonding strength to various substrates and effectively reduces friction between the substrate and other materials.

[0039] Example 1: A hydrophilic polymer, N,N-dimethylacrylamide, and an electrolyte monomer, 1-vinyl-imidazolium bromide, were solution polymerized in a solvent at a mass ratio of 1:0.2. The polymer solution was then dried to obtain a hydrophilic polymer. The polymerization temperature was 5°C for 48 hours, and the drying temperature was 100°C for 12 hours. The resulting hydrophilic polymer was mixed with acetic acid lignin in a co-solvent, N,N-dimethylformamide, in a specific proportion and stirred thoroughly. A uniform coating was then added with a certain amount of hyaluronic acid. The mass ratio of lignin to hydrophilic polymer was 2:1, and the amount of hyaluronic acid added was 1.5% of the total amount of lignin and hydrophilic polymer. The coating had a solids content of 4%. The resulting coating was evenly applied to a glass plate and completely dried at 30°C. After the solvent dried, the glass plate coated with the lignin-based coating was immersed in 3°C water for 24 hours to allow the dried coating to swell, resulting in a lignin-based hydrogel coating.

[0040] Example 2: A hydrophilic polymer monomer, N-isopropylacrylamide, and an electrolyte monomer, 1-vinyl-imidazolium bromide, were solution polymerized in a solvent at a mass ratio of 1:0.2. The polymer solution was then dried to obtain a hydrophilic polymer. The polymerization temperature was 10°C for 40 hours, and the drying temperature was 90°C for 18 hours. The resulting hydrophilic polymer was then mixed with acetic acid lignin in a co-solvent, N,N-dimethylformamide, in a specific ratio and stirred thoroughly. A uniform coating was then added with a certain amount of hyaluronic acid. The mass ratio of lignin to hydrophilic polymer was 2:3, and the amount of hyaluronic acid added was 1.2% of the total amount of lignin and hydrophilic polymer. The coating had a solids content of 6%. The resulting coating was evenly applied to a glass plate and completely dried at 20°C. After the solvent dried, the glass plate coated with the lignin-based coating was immersed in 10°C water for 30 hours to allow the dried coating to swell, resulting in a lignin-based hydrogel coating.

[0041] Example 3: After vacuum drying alkaline lignin at 60°C for 24 hours, 1 g of the dried sample was added to 20 ml of acetic anhydride-pyridine solution (5:5, v / v) and stirred at room temperature for 48 hours. After cooling the reaction mixture, an excess of cold distilled water was added and centrifuged to obtain a solid precipitate. The solid precipitate was washed three times with cold distilled water and vacuum dried at 60°C for 24 hours to obtain acetylated lignin. A hydrophilic polymer, N,N-dimethylacrylamide, and an electrolyte monomer, 1-vinyl-imidazolium bromide, were solution-polymerized in a solvent at a mass ratio of 1:0.2. The polymer solution was then dried to obtain a hydrophilic polymer. The polymerization temperature was 20°C for 35 hours, and the drying temperature was 80°C for 20 hours. The resulting hydrophilic polymer and acetylated lignin were mixed in a co-solvent, N,N-dimethylformamide, and stirred thoroughly. A uniform coating was then added with a certain amount of hyaluronic acid. The mass ratio of acetylated lignin to hydrophilic polymer was 2:1, the amount of hyaluronic acid added was 1% of the total amount of lignin and hydrophilic polymer, and the coating had a solid content of 8%. The resulting coating was evenly applied to a glass plate and completely dried at 40°C. After the solvent dried, the glass plate coated with the lignin-based coating was immersed in water at 15°C for 35 hours to allow the dried coating to swell, resulting in a lignin-based hydrogel coating.

[0042] Example 4: A hydrophilic polymer (N,N-dimethylacrylamide) and an electrolyte monomer (1-vinyl imidazolium bromide) were solution-polymerized in a solvent at a mass ratio of 1:0.2. The polymer solution was then dried to obtain a hydrophilic polymer. The polymerization temperature was 30°C for 30 hours, and the drying temperature was 70°C for 30 hours. The resulting hydrophilic polymer was then mixed with acetic acid lignin in a co-solvent (N,N-dimethylsulfoxide) at a specific ratio and thoroughly stirred. A certain amount of hyaluronic acid was then added to form a uniform coating. The mass ratio of lignin to hydrophilic polymer was 2:3, and the amount of hyaluronic acid added was 0.7% of the total amount of lignin and hydrophilic polymer. The coating had a solids content of 12%. The resulting coating was evenly applied to a glass plate and completely dried at 50°C. After the solvent dried, the glass plate coated with the lignin-based coating was immersed in 20°C water for 40 hours to allow the dried coating to swell, resulting in a lignin-based hydrogel coating.

[0043] Example 5: A hydrophilic polymer, N,N-dimethylacrylamide, and an electrolyte monomer, 1-vinyl-imidazolium bromide, were solution-polymerized in a solvent at a mass ratio of 1:0.2. The polymer solution was then dried to obtain a hydrophilic polymer. The polymerization temperature was 50°C for 20 hours, and the drying temperature was 40°C for 36 hours. The resulting hydrophilic polymer was then mixed with acetic acid lignin in a co-solvent, N,N-dimethylformamide, at a mass ratio of 2:2. The solids content of the coating was 15%, and the mixture was thoroughly stirred to form a uniform coating. The resulting coating was evenly applied to a 316 stainless steel plate and completely dried at -3°C. After drying, the 316 stainless steel plate coated with the lignin-based coating was immersed in 25°C water for 50 hours to allow the dried coating to swell, resulting in a lignin-based hydrogel coating.

[0044] Example 6: A hydrophilic polymer monomer, N,N-dimethylacrylamide, and an electrolyte monomer, 1-butyl-3-methylimidazolium bromide, were solution-polymerized in deionized water to form a polymer solution. The polymer solution was then dried to obtain a hydrophilic polymer. The polymerization temperature was 70°C for 12 hours, and the drying temperature was 20°C for 40 hours. The resulting hydrophilic polymer was mixed with acetic acid lignin in its co-solvent, N,N-dimethylformamide, in a specific proportion and stirred thoroughly. A certain amount of hyaluronic acid was then added to form a uniform coating. The mass ratio of lignin to hydrophilic polymer was 2:1, and the amount of hyaluronic acid added was 0.3% of the total amount of lignin and hydrophilic polymer. The coating had a solids content of 18%. The resulting coating was evenly dip-coated onto a 316 stainless steel rod and completely dried at 15°C. After drying, the 316 stainless steel rod coated with the lignin-based coating was immersed in 30°C water for 60 hours to allow the dried coating to swell, resulting in a lignin-based hydrogel coating.

[0045] Example 7: A hydrophilic polymer, N,N-dimethylacrylamide, and an electrolyte monomer, (3-acrylamidopropyl)trimethylammonium chloride, were solution polymerized in a solvent at a mass ratio of 1:0.5 to form a hydrophilic polymer solution. The polymer solution was then dried to obtain a hydrophilic polymer. The polymerization temperature was 90°C for 5 hours, and the drying temperature was 10°C for 48 hours. The resulting hydrophilic polymer was then mixed with hydrophobic lignin or a hydrophobically modified lignin derivative in a co-solvent, N,N-dimethylformamide, in a specific proportion and stirred thoroughly. A certain amount of hyaluronic acid was then added to form a uniform coating. The mass ratio of lignin to hydrophilic polymer was 2:3, and the amount of hyaluronic acid added was 1% of the total amount of lignin and hydrophilic polymer. The coating had a solids content of 20%. The resulting coating was evenly applied to a wooden board using a roller and completely dried at 5°C. After the solvent dried, the board coated with the lignin-based coating was immersed in 40°C water for 70 hours to allow the dried coating to swell, resulting in a lignin-based hydrogel coating.

[0046] Figure 1 The peeling energy results of the lignin hydrogel coatings of Examples 1-5 after 90° peeling test are shown. The substrates coated with the lignin hydrogel coatings of Examples 1-4 are glass, and the substrate coated with the lignin hydrogel coating of Example 5 is stainless steel. The lignin hydrogel coatings prepared in Examples 1-5 all have high bonding strength to the substrates (>200 J / m 2 ). Among them, the lignin hydrogel coating prepared in Example 4 has the highest bonding strength with glass.

[0047] Figure 2 1 is a graph showing the test results of the friction coefficient of the lignin hydrogel coating of Examples 1-4 against metal aluminum; Figure 2 It can be seen that with the increase of the amount of hyaluronic acid added, the friction coefficient is significantly reduced. It can be seen that adding hyaluronic acid can effectively increase the surface lubricity of the lignin hydrogel coating.

[0048] Figure 3 Schematic diagram of the experiment of testing the sliding friction resistance of a 316 stainless steel rod coated with a lignin hydrogel coating and a 316 stainless steel rod without a coating against a curved silicone tube in Example 6;

[0049] Figure 4 The friction resistance-displacement curves of the 316 stainless steel rod coated with lignin hydrogel and the stainless steel rod without coating against the inner wall of the curved silicone tube in Example 6 are shown in FIG. The maximum friction resistance of the uncoated stainless steel rod is ≈6.55N, while the maximum friction resistance of the coated stainless steel rod is only 0.83N ( Figure 4 ). The friction resistance of the coated stainless steel rod is significantly lower than that of the uncoated stainless steel rod. Figure 5The following are sample images of the lignin hydrogel coatings of Examples 1-7. The present invention utilizes the hydrophobic properties of lignin to prepare a lignin-based hydrogel coating that physically adheres to a substrate. This coating exhibits high adhesion to a variety of substrate surfaces, is easy to apply, easily washable, and is reusable.

Claims

1. A method for preparing a reusable high-adhesion lignin hydrogel coating, characterized in that: Please follow the steps below to implement: Step 1: mixing a hydrophilic polymer monomer, an electrolyte monomer and water to form a hydrophilic polymer solution through solution polymerization, and drying to obtain a hydrophilic polymer; The mass ratio of the hydrophilic polymer monomer to the electrolyte monomer is 1:0.01-1; Step 2: mixing a hydrophilic polymer, hydrophobic lignin, and a solvent, stirring thoroughly, adding hyaluronic acid, and mixing evenly to obtain a coating; The mass ratio of hydrophobic lignin to hydrophilic polymer is 2:1-3, and the amount of hyaluronic acid added is 0.1-2% of the total amount of hydrophobic lignin and hydrophilic polymer; Step 3: evenly apply the prepared coating on the substrate, allow the solvent to completely dry, and then immerse the substrate covered with the dry coating in water to allow the dry coating to swell, thereby obtaining a lignin hydrogel coating.

2. The method for preparing a reusable high-adhesion lignin hydrogel coating according to claim 1, characterized in that: In the step 1, the hydrophilic polymer monomer is any one of N,N-dimethylacrylamide, methacrylamide, methacrylic acid, and N-isopropylacrylamide.

3. The method for preparing a reusable high-adhesion lignin hydrogel coating according to claim 1, characterized in that: In the step 1, the electrolyte monomer is any one of 1-vinyl-imidazole bromide, 1-ethyl-3-methylimidazole bromide, 1-propyl-3-methylimidazole bromide, 1-butyl-3-methylimidazole bromide, 1-pentyl-3-methylimidazole bromide, 1-hexyl-3-methylimidazole bromide, 3-(methacrylamido)propyltrimethylammonium chloride, (3-acrylamidopropyl)trimethylammonium chloride, acryloyloxyethyltrimethylammonium chloride, and 2-acrylamido-2-methyl-1-propanesulfonic acid sodium.

4. The method for preparing a reusable high-adhesion lignin hydrogel coating according to claim 1, characterized in that: In the step 1, the polymerization temperature is 1° C. to 95° C., and the polymerization time is 1 to 48 hours; the drying temperature is 0° C. to 100° C., and the drying time is 5 to 48 hours.

5. The method for preparing a reusable high-adhesion lignin hydrogel coating according to claim 1, characterized in that: In step 2, the hydrophobic lignin is any one of acetic acid lignin, sulfate lignin, dioxane lignin, formic acid lignin, acetylated modified lignin, and alkylene oxide modified lignin; and the solvent is any one of N,N-dimethylformamide, acetone, pyridine, N,N-dimethyl sulfoxide, dioxane, and ethyl acetate.

6. The method for preparing a reusable high-adhesion lignin hydrogel coating according to claim 1, characterized in that: In step 3, the solvent is completely dried at a temperature of -20°C to 50°C; the soaking temperature is 0°C to 50°C, and the soaking time is 24 to 72 hours.

7. The method for preparing a reusable high-adhesion lignin hydrogel coating according to claim 1, characterized in that: In step 3, the substrate is any one of a wood substrate, a metal substrate, a glass substrate, a silicone substrate, and a polytetrafluoroethylene substrate.

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