A composite superhydrophobic paper based on alkyl ketene dimers and metal polyphenol networks and its preparation method.

Abstract

The application discloses a kind of composite super-hydrophobic paper based on alkyl ketene dimer and metal polyphenol network and preparation method thereof, belong to functional paper-based material field.The method is first immersed in 0.25%~5% alkyl ketene dimer emulsion in cellulose paper, is dried at 90~110 DEG C and is cured 48-96h to prepare modified paper;Then, the pH is 8.0-9.0 of tris-hydroxymethyl aminomethane hydrochloride buffer solution, hydrochloric acid dopamine is dissolved in the buffer solution to form dopamine solution, and the concentration is 0.25~20mg / mL of metal ion solution;Finally, the modified paper is immersed in dopamine solution and metal ion solution in turn, and is dried to obtain composite super-hydrophobic paper.The obtained composite super-hydrophobic paper uses cellulose paper-based material as substrate, and hydrophobic layer and metal polyphenol network layer are formed on the surface in turn, the composite paper has super-hydrophobic performance, water barrier performance and photo-thermal response performance, the preparation process is simple, and is suitable for waterproof packaging, self-cleaning surface, anti-icing and deicing and photo-thermal antibacterial and other fields.

Description

Technical Field

[0001] This invention belongs to the field of functional paper-based materials technology, specifically relating to a composite superhydrophobic paper based on the synergistic modification of alkyl ketene dimers and metal polyphenol networks, and its preparation method. More specifically, it relates to a composite paper material with superhydrophobic properties, water barrier properties, and photothermal response properties, obtained by using cellulose paper-based material as a substrate, first pre-hydrophobizing it with alkyl ketene dimers, and then constructing a metal polyphenol network formed by dopamine and polyvalent metal ions on its surface. Background Technology

[0002] Cellulose-based paper materials have advantages such as wide availability, low cost, renewability, biodegradability, and ease of processing, and have broad application prospects in packaging, filtration, protection, flexible devices, and functional interfaces. However, the large number of hydroxyl groups in the cellulose molecular chain gives paper-based materials a naturally strong hydrophilicity and hygroscopicity. When paper comes into contact with liquid water or is in a high-humidity environment, moisture can easily penetrate the paper interior rapidly through capillary action, leading to fiber swelling, decreased strength, and structural damage, thus limiting its application in waterproof, stain-resistant, self-cleaning, and freeze-resistant applications.

[0003] To improve the water resistance of paper-based materials, existing technologies typically employ hydrophobic treatment methods such as sizing, coating, or chemical modification. Alkyl ketene dimers (AKD), commonly used neutral sizing agents in the paper industry, can introduce long-chain hydrophobic groups by reacting with cellulose hydroxyl groups or aligning them on the fiber surface, thereby reducing the surface energy of paper and improving its hydrophobic properties. However, when alkyl ketene dimers are used alone to treat paper-based materials, it is usually difficult to consistently obtain a superhydrophobic surface with a static water contact angle greater than 150° and a low roll-off angle. The resulting material also has relatively limited functionality, mainly confined to passive waterproofing.

[0004] In recent years, metal polyphenol networks (MPNs) have attracted widespread attention due to their simple construction process, strong substrate adaptability, and tunable functionality. Dopamine molecules contain catechol groups, which can undergo oxidative polymerization under weakly alkaline conditions and further coordinate with polyvalent metal ions to form a functional network layer with a certain degree of roughness on the substrate surface. Existing studies have shown that some metal polyphenol networks (MPNs) possess strong light absorption capacity and good photothermal conversion performance, and can be applied in fields such as photothermal drive, photothermal antibacterial, and de-icing / anti-icing.

[0005] However, existing technologies mainly focus on using alkyl ketene dimers to improve the hydrophobicity of paper, or using dopamine-metal ion systems to construct functional interfaces. There is a lack of a technical solution that can effectively combine a low surface energy layer with micro / nano rough structures on the surface of paper-based materials. In particular, there is a lack of a simple process for developing composite paper materials that are suitable for paper-based materials and can simultaneously impart superhydrophobic, water-barrier, and photothermal responsive properties to the materials, along with their preparation methods.

[0006] Therefore, developing a composite superhydrophobic paper based on the synergistic modification of alkyl ketene dimers and metal polyphenol networks and its preparation method is of great significance for expanding the application of paper-based materials in waterproof packaging, self-cleaning surfaces, anti-icing and de-icing, photothermal antibacterial and smart functional materials. Summary of the Invention

[0007] The purpose of this invention is to provide a composite superhydrophobic paper based on alkyl ketene dimers and metal polyphenol networks, in order to solve the problems of poor water resistance, limited functionality, and difficulty in simultaneously possessing superhydrophobic and photothermal response properties in existing paper-based materials.

[0008] Another objective of this invention is to provide a method for preparing the above-mentioned composite superhydrophobic paper, which is simple in process, mild in conditions, and uses water as the main treatment medium, and is suitable for widespread application.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a composite superhydrophobic paper based on alkyl ketene dimers and metal polyphenol networks includes the following steps: (1) The cellulose paper base material is impregnated in an alkyl ketene dimer emulsion with a mass concentration of 0.25% to 5%, and then dried at 90 to 110°C. After drying, it is aged at room temperature for 48 to 96 hours to obtain alkyl ketene dimer modified paper. (2) Dissolve tris(hydroxymethyl)aminomethane hydrochloride (Tris-HCl) in deionized water and adjust the pH to 8.0-9.0 with sodium hydroxide solution to obtain a buffer solution; (3) Add dopamine hydrochloride to the buffer solution and stir until completely dissolved to obtain a dopamine (DA) solution; (4) Dissolve the metal ion salt in deionized water and stir until completely dissolved to obtain a metal ion solution with a concentration of 0.25 to 20 mg / mL; (5) The alkyl ketene dimer modified paper obtained in step (1) is immersed in the dopamine solution obtained in step (3) and reacted for 10-24 hours; after being taken out and cleaned, it is immersed in the metal ion solution obtained in step (4) and reacted for 1-5 hours; then it is taken out and dried to obtain the composite superhydrophobic paper based on alkyl ketene dimer and metal polyphenol network.

[0010] Preferably, the cellulose paper base material in step (1) is filter paper, kraft paper, packaging paper or other cellulose-based base paper.

[0011] Preferably, in step (3), the amount of dopamine hydrochloride added is 0.3 to 3 g per 100 mL of buffer solution.

[0012] Preferably, the multivalent metal ion in step (4) is selected from Fe. 3+ Al 3+ Cu 2+ At least one of them.

[0013] Preferably, the drying temperature in step (5) is 40-60°C and the drying time is 10-60 min.

[0014] Preferably, when the multivalent metal ion is Fe... 3+ When the composite superhydrophobic paper is obtained, it has better superhydrophobic properties and photothermal response properties.

[0015] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention combines alkyl ketene dimer pre-hydrophobic treatment with the construction of a metal polyphenol network to simultaneously achieve low surface energy regulation and micro / nano rough structure construction on the surface of paper-based materials, thereby giving the resulting material excellent superhydrophobic properties. In a preferred embodiment, the static water contact angle of the resulting material can reach 157.8°, exhibiting obvious superhydrophobic characteristics; (2) The composite paper obtained by this invention has excellent water barrier properties. Compared with unmodified paper, it can significantly reduce the water absorption of the paper; compared with paper treated only with alkyl ketene dimers, the waterproof performance is further improved. In a preferred embodiment, the Cobb value of the material can be reduced to 4.3 g / m²; (3) This invention further constructs a metal polyphenol network on the surface of alkyl ketene dimer-modified paper, thereby endowing the material with significant photothermal conversion capabilities. Preferably, when the metal ion is Fe... 3+ When the composite paper is irradiated with 600nm red light for 30s, it can rapidly heat up to 88.3℃, making it suitable for photothermal de-icing, antibacterial and thermal response interfaces. (4) The present invention adopts a process that combines impregnation and in-situ assembly. The process is simple, easy to operate, and the reaction conditions are mild, making it suitable for promotion and application in the functionalization of paper-based materials. (5) The composite paper provided by the present invention has multiple properties such as superhydrophobicity, self-cleaning, water barrier and photothermal response, and has good application prospects in waterproof packaging, self-cleaning surface, anti-icing and antifreeze, photothermal de-icing and intelligent paper-based devices. Attached Figure Description

[0016] Figure 1 This is an infrared thermal image of the composite superhydrophobic paper of the present invention under 600nm red light irradiation. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to the embodiments, but the scope of protection of the present invention is not limited thereto. In the following embodiments, unless otherwise specified, all reagents used are of analytical grade, and the experimental methods are conventional methods in the art or methods recommended by the manufacturer.

[0018] Comparative Example 1: Base Paper The qualitative filter paper was dried in a 40℃ oven for 30 minutes, then removed and cooled to room temperature in a desiccator. This was recorded as Base.

[0019] Comparative Example 2: Alkyl ketene dimer modified paper Filter paper was immersed in a 0.5% (w / w) alkyl ketene dimer emulsion for 3 min, then dried in an oven at 105℃ for 5 min, and then cured at room temperature for 72 h to obtain alkyl ketene dimer modified paper, denoted as AKD-Paper; filter paper was immersed in a 0.5% (w / w) AKD emulsion for 3 min, then dried in an oven at 105℃ for 5 min, and then cured at room temperature for 72 h to obtain AKD modified paper, denoted as AKD-Paper.

[0020] Comparative Example 3: Dopamine-Iron Ion Modified Paper (1) Dissolve Tris-HCl in deionized water, adjust the pH to 8.5 with sodium hydroxide solution, and make up to volume to obtain Tris-HCl buffer solution; (2) Dissolve 1.5g of dopamine hydrochloride in 100mL of the Tris-HCl buffer solution and stir until completely dissolved to obtain a dopamine solution; (3) Weigh 0.05g of ferric chloride and dissolve it in 100mL of deionized water to obtain Fe with a concentration of 0.5mg / mL. 3+ Solution; (4) The base paper is immersed in the dopamine solution obtained in step (2) and reacted for 16 hours. It is then removed and rinsed with deionized water; and then immersed in the Fe obtained in step (3). 3+ The mixture was reacted in the solution for 2 hours, then removed and dried at 45°C for 30 minutes to obtain dopamine-iron ion modified paper, denoted as DA-Fe-Paper.

[0021] Comparative Example 4: Dopamine-Copper Ion Modified Paper This comparative example is basically the same as Comparative Example 3, except that the metal ions used are Cu at a concentration of 0.5 mg / mL. 2+ The solution was used to obtain a sample, which was denoted as DA-Cu-Paper.

[0022] Comparative Example 5: Dopamine-aluminum ion modified paper This comparative example is basically the same as Comparative Example 3, except that the metal ions used are Al at a concentration of 0.5 mg / mL. 3+ The solution was used to obtain a sample, which was denoted as DA-Al-Paper.

[0023] Example 1 (1) The pretreatment of the base paper was the same as that of Comparative Example 1; (2) The base paper was modified with alkyl ketene dimer according to the method described in Comparative Example 2 to obtain AKD-Paper; (3) Add 0.3g of dopamine hydrochloride to 100mL of Tris-HCl buffer and stir until completely dissolved to obtain a dopamine solution; (4) The AKD-Paper was immersed in the above dopamine solution for 16 hours; after being removed and washed, it was then immersed in 0.5 mg / mL Fe. 3+ The reaction was carried out in the solution for 2 hours; after removal, it was dried at 45℃ for 30 minutes to obtain the composite superhydrophobic paper, denoted as AKD-DA-Fe-Paper-1.

[0024] Example 2 This embodiment is basically the same as that of embodiment 1, except that the amount of dopamine hydrochloride added in step (3) is 1.5g / 100mL, and the resulting sample is recorded as AKD-DA-Fe-Paper-2.

[0025] Example 3 This embodiment is basically the same as Example 2, except that a Cu concentration of 0.5 mg / mL is used. 2+ Solution instead of Fe 3+ The solution was used as the source of metal ions, and the resulting sample was denoted as AKD-DA-Cu-Paper.

[0026] Example 4 This embodiment is basically the same as Example 2, except that it uses Al at a concentration of 0.5 mg / mL. 3+ Solution instead of Fe 3+ The solution was used as the source of metal ions, and the resulting sample was denoted as AKD-DA-Al-Paper.

[0027] Performance testing (1) Water contact angle test: The static water contact angle of each sample surface was tested using a contact angle measuring instrument to evaluate the hydrophobic properties of the sample surface; (2) The water absorption performance test was conducted by using the Cobb method to test the water absorption of each sample in order to evaluate its water barrier performance. (3) Photothermal performance test: The sample surface was irradiated with a 600nm red light source and the temperature change was recorded with an infrared thermal imager.

[0028] Test results show that:

[0029] The contact angles and surface energies of different composite papers are shown in Table 1. Both the base paper and the MPN-modified paper alone struggled to form stable hydrophobic surfaces, while the hydrophobicity of the paper surface was significantly improved after AKD modification. Further introduction of DA-Fe based on AKD modification... 3+ Network and DA-Cu 2+ After the network was applied, the water contact angle increased significantly, exceeding 150°, reaching superhydrophobicity, indicating that AKD and the metal polyphenol network have a significant synergistic effect.

[0030] The contact angles and surface energies of different samples are shown in Table 1. Table 1 shows that the original paper and the paper modified only by the metal polyphenol network were both unable to form a stable hydrophobic surface. After modification with alkyl ketene dimers, the hydrophobicity of the paper surface was significantly improved, with a water contact angle reaching 130.5 ± 0.9°. Furthermore, after introducing a dopamine-metal ion network on top of the alkyl ketene dimer modification, the water contact angle of the samples increased significantly, exceeding 150°, reaching a superhydrophobic level. In particular, the sample obtained in Example 2 achieved a water contact angle of 157.8 ± 0.9° and a surface energy reduced to 3.18 ± 0.15 mJ / m², indicating a significant synergistic effect between the low surface energy interface provided by the alkyl ketene dimer and the rough structure formed by the metal polyphenol network.

[0031] Table 1. Contact angle and surface energy (mean ± standard deviation) of different samples

[0032] (2) Waterproof performance of different samples The waterproof performance of different samples is shown in Table 2. Table 2 shows that the Cobb value of the base paper was (149.2±1.0) g / m², indicating a high water absorption rate. After modification with alkyl ketene dimers, the Cobb value decreased to (36.7±0.7) g / m², significantly improving the waterproof performance. Further construction of a metal polyphenol network on top of the alkyl ketene dimer modification resulted in a further significant decrease in the Cobb value, with the sample in Example 2 showing a Cobb value reduction to (4.3±0.4) g / m². These results demonstrate that the composite structure constructed in this invention can effectively inhibit the penetration and absorption of liquid water in paper, significantly improving the water barrier properties of the paper.

[0033] Table 2 Waterproof performance of different samples (mean ± standard deviation)

[0034] (3) Photothermal properties of different samples The photothermal properties of different samples are shown in Table 3. As can be seen from Table 3, the samples containing the metal polyphenol network all exhibited significant photothermal heating capacity, while the original paper and paper modified only by alkyl ketene dimers showed weaker heating effects. Among them, dopamine-Fe... 3+ The system exhibited the best photothermal performance. In Example 2, under conditions of room temperature (18℃) and 600nm red light irradiation for 30s, the surface equilibrium temperature reached 88.3±0.7℃, with a temperature rise rate of 2.34℃ / s, significantly superior to other samples. This indicates that Fe... 3+ The metal polyphenol network involved in the construction has better light absorption capacity and photothermal conversion efficiency.

[0035] Table 3. Photothermal properties of different samples (room temperature 18℃, illumination 30s) (mean ± standard deviation)

[0036] In summary, this invention successfully prepared a composite paper material possessing superhydrophobic properties, water barrier properties, and photothermal response properties through the synergistic effect of alkyl ketene dimer pre-hydrophobication treatment and in-situ assembly of a metal polyphenol network. Among these, Fe... 3+ When used as a metal ion, the resulting composite paper exhibits superior performance in terms of superhydrophobicity, waterproofing, and photothermal properties.

[0037] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Any modifications, equivalent substitutions, and improvements made by those skilled in the art without departing from the spirit and principles of the present invention should be included within the scope of protection of the present invention. The scope of protection of the present invention should be determined by the claims.

Claims

1. A method for preparing a composite superhydrophobic paper based on alkyl ketene dimers and metal polyphenol networks, characterized in that, Includes the following steps: (1) The cellulose paper base material is impregnated in an alkyl ketene dimer emulsion with a mass concentration of 0.25% to 5%, and then dried at 90 to 110°C. After drying, it is aged at room temperature for 48 to 96 hours to obtain alkyl ketene dimer modified paper. (2) Dissolve tris(hydroxymethyl)aminomethane hydrochloride in deionized water and adjust the pH to 8.0-9.0 with sodium hydroxide solution to obtain a buffer solution; (3) Add dopamine hydrochloride to the buffer solution and stir until completely dissolved to obtain a dopamine solution; (4) Dissolve the metal ion salt in deionized water and stir until completely dissolved to obtain a metal ion solution with a concentration of 0.25 to 20 mg / mL; (5) The alkyl ketene dimer modified paper obtained in step (1) is immersed in the dopamine solution obtained in step (3) and reacted for 10-24 hours; after being taken out and cleaned, it is immersed in the metal ion solution obtained in step (4) and reacted for 1-5 hours; then it is taken out and dried to obtain a composite superhydrophobic paper based on alkyl ketene dimer and metal polyphenol network.

2. The preparation method according to claim 1, characterized in that, The cellulose paper base material mentioned in step (1) is filter paper, kraft paper, packaging paper or other cellulose-based base paper.

3. The preparation method according to claim 1, characterized in that, The pH of the buffer solution in step (2) is 8.

5.

4. The preparation method according to claim 1, characterized in that, In step (3), the amount of dopamine hydrochloride added is 0.3 to 3 g per 100 mL of buffer solution.

5. The preparation method according to claim 1, characterized in that, The multivalent metal ions provided by the metal ion salt in step (4) are selected from Fe. 3+ Al 3+ and Cu 2+ At least one of them.

6. The preparation method according to claim 1, characterized in that, The drying temperature in step (5) is 40-60℃ and the drying time is 10-60 min.

7. A composite superhydrophobic paper based on alkyl ketene dimers and a metal polyphenol network, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 6, and uses cellulose paper-based material as a substrate, wherein an alkyl ketene dimer hydrophobic layer and a metal polyphenol network layer are sequentially formed on the surface of the cellulose paper-based material, wherein the metal polyphenol network layer is formed by coordination between dopamine and polyvalent metal ions.

8. The composite superhydrophobic paper according to claim 7, characterized in that, The composite superhydrophobic paper simultaneously possesses superhydrophobic properties, water barrier properties, and photothermal response properties.

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