Polydopamine-based super-hydrophobic paper as well as preparation method and application thereof

Abstract

The invention relates to the technical field of functional materials, in particular to super-hydrophobic paper based on polydopamine as well as a preparation method and application of the super-hydrophobic paper. Natural filter paper serves as a substrate and is soaked in a dopamine hydrochloric acid solution, filter paper modified by a polydopamine middle layer is obtained through dopamine oxidation self-polymerization, the filter paper modified by the polydopamine middle layer is soaked in a long-carbon-chain silane coupling agent ethanol solution, hydrophobic modification is conducted, and the super-hydrophobic paper based on the polydopamine is obtained. The water contact angle of the obtained super-hydrophobic paper reaches 152 degrees, the super-hydrophobic paper has excellent waterproof, oil-proof and self-cleaning performance, the raw materials are environmentally friendly, the process is simple, the super-hydrophobic paper is suitable for the field of food packaging, a degradable solution is provided for replacing traditional plastic packaging, and the super-hydrophobic paper has remarkable environment-friendly and economic value.

Description

Technical Field

[0001] The present invention relates to the technical field of functional materials, and in particular to a super-hydrophobic paper based on polydopamine, and a preparation method and application thereof. Background Art

[0002] Replacing plastic with paper has become a hot topic. Traditional plastic packaging faces strict restrictions due to its non-degradability. While paper packaging offers environmental advantages, it is susceptible to corrosion by moisture and oil, leading to performance degradation. In recent years, superhydrophobic surface technology has provided a new direction for the development of high-performance paper-based packaging.

[0003] Traditional superhydrophobic paper-based materials often rely on methods such as fluorosilane modification, nanoparticle spraying, or chemical vapor deposition, which pose challenges such as complex processes, high costs, and environmental pollution. Direct modification of filter paper is difficult due to its porous structure and hydrophilicity. Existing techniques (such as plasma treatment and sol-gel methods) can easily damage the fiber structure or result in uneven coatings. Furthermore, traditional paper-based superhydrophobic materials exhibit poor mechanical friction resistance. Finding a simpler, gentler method to produce wear-resistant superhydrophobic paper is an urgent challenge.

[0004] Polydopamine (PDA) can be deposited in situ on a variety of substrates under mild conditions due to its excellent adhesion and reactivity. However, pure PDA coatings are highly hydrophilic. Existing research has focused primarily on the adhesive properties of PDA, while efficient and environmentally friendly solutions for achieving superhydrophobicity in filter paper through PDA-mediated coatings remain lacking. Summary of the Invention

[0005] To address the deficiencies in the prior art, the present invention provides a polydopamine-based superhydrophobic paper, its preparation method, and its application. The present invention utilizes polydopamine and a long carbon-chain silane coupling agent for synergistic modification to construct a stable micro-nanohydrophobic structure on the filter paper surface. This structure is then modified with a low-surface-energy substance to significantly improve its waterproof and oil-proof properties and mechanical durability. This overcomes the performance shortcomings of existing paper-based packaging in humid environments and expands its potential for application in areas such as fresh food and fast food packaging.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions: A method for preparing super-hydrophobic paper based on polydopamine, characterized in that it comprises the following steps: Using natural filter paper as the substrate, it was immersed in a dopamine hydrochloric acid solution, and the dopamine was oxidized and self-polymerized to obtain a filter paper modified with a polydopamine intermediate layer; The filter paper modified with the polydopamine intermediate layer was immersed in an ethanol solution of a long carbon chain silane coupling agent for hydrophobic modification to obtain a superhydrophobic paper based on polydopamine.

[0007] The present invention immerses the filter paper in a dopamine hydrochloric acid solution to polymerize it into polydopamine, which is then deposited on the fiber surface to form a micro-nano rough structure, which serves as a modified intermediate layer. Because dopamine (DA) is a common bioadhesive, it is often used as a modifier to improve the hydrophilicity and reactivity of the substrate. In addition, the modification using dopamine is convenient and simple to operate, has little impact on the substrate, and can also improve the stability and hydrophilicity of the film. The filter paper modified with the polydopamine intermediate layer is immersed in an ethanol solution of a long carbon chain silane coupling agent. The surface of the dopamine particles is coated with a layer of polymer film, which is the long carbon chain silane coupling agent. This proves that the hydrophobic treatment has been successfully carried out, reducing the surface energy of the paper and making the paper have certain hydrophobic properties.

[0008] In a preferred embodiment of the present invention, the long carbon chain silane coupling agent is a long carbon chain silane coupling agent or a long carbon chain alkylamine, including one or more of dodecyltrimethoxysilane, hexadecyltrimethoxysilane, and octadecyltrimethoxysilane, or one or more of dodecylamine, hexadecylamine, and octadecylamine.

[0009] In a preferred embodiment of the present invention, the concentration of the dopamine hydrochloric acid solution is 0.5 mg / mL-2 mg / mL.

[0010] In a preferred embodiment of the present invention, the filter paper is immersed in the dopamine hydrochloric acid solution for 6 hours to 12 hours.

[0011] In a preferred embodiment of the present invention, in the ethanol solution of the long carbon chain silane coupling agent, the volume ratio of the long carbon chain silane coupling agent to ethanol is 0.5:100-1:100.

[0012] In a preferred embodiment of the present invention, the hydrophobic modification temperature is 25° C., and the time is 0.5 hour to 1 hour.

[0013] In a preferred embodiment of the present invention, the filter paper is immersed in the dopamine hydrochloric acid solution for 12 hours.

[0014] In a preferred embodiment of the present invention, the volume ratio of the long carbon chain silane coupling agent to ethanol is 1:100.

[0015] Another object of the present invention is to provide a super-hydrophobic paper prepared by any of the preparation methods described above, wherein the water contact angle is ≥150° and the surface has a micro-nano composite rough structure.

[0016] The super-hydrophobic paper described in the present invention is used in the fields of food packaging, antifouling materials or moisture-proofing of electronic devices.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention uses natural filter paper as a substrate and immerses it in an aqueous solution of dopamine hydrochloride. PDA, a polymer, is uniformly deposited on the filter paper fiber surface through self-polymerization under weakly alkaline conditions (pH 8.5-9.0), forming a micro-nanoscale rough structure without the need for pretreatment or expensive equipment. Compared to traditional spray coating methods, PDA firmly bonds to cellulose fibers through hydrogen bonds and π-π interactions, preventing coating shedding. Long-chain silane coupling agents are colorless to pale yellow liquids that readily hydrolyze to form silanols. Simultaneously, the hydroxyl groups on the silanols undergo dehydration condensation with hydroxyl groups on the fiber surface to form low-surface-energy siloxanes, forming a two-dimensional, ordered hydrophobic film. This provides enhanced water-repellent properties and is environmentally friendly. While the current PDA modification and long-chain silane coupling agent self-assembly process requires strict control of reaction conditions, continuous coating technology could be used in the future to improve production efficiency and reduce costs. Multifunctional integration could also be introduced, incorporating natural antimicrobial agents or antioxidants into super-hydrophobic substrates to develop intelligent packaging systems with both antibacterial and antioxidant properties. The super-hydrophobic paper produced by the present invention is modified using polydopamine and an ethanol solution of a long carbon-chain silane coupling agent. This creates a stable micro-nanohydrophobic structure on the paper fiber surface and eliminates organic volatiles. The modification process is simple, the raw materials are readily available, and the paper is suitable for large-scale production.

[0018] 2. This invention utilizes polydopamine (PDA) and an ethanol solution of a long-chain silane coupling agent to create a superhydrophobic paper. This creates a stable micro-nanohydrophobic structure on the paper fiber surface. Because PDA is rich in reactive groups, such as phenolic hydroxyl and amino groups, the amount of silane coupling agent required can be reduced by 30% to 50%, significantly improving its water resistance and mechanical durability. This overcomes the performance limitations of existing paper-based packaging in humid environments and expands its potential for application in fresh food and fast food packaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Figures a1 to a3 are SEM images of the original filter paper fibers prepared in Comparative Example 1 of the present invention at different magnifications.

[0020] Figure 2 These are SEM images of the filter papers modified with the polydopamine intermediate layer prepared in Comparative Examples 2 to 4 at different magnifications, wherein b1 to b3 are samples of Comparative Example 2, c1 to c3 are samples of Comparative Example 3, and d1 to d3 are samples of Comparative Example 4.

[0021] Figure 3 The SEM images of the polydopamine-based superhydrophobic paper prepared in Examples 1, 2, and 3 at different magnifications are shown, wherein e1 to e3 are samples of Example 1, f1 to f3 are samples of Example 2, and g1 to g3 are samples of Example 3.

[0022] Figure 4This is the SEM-EDS image of the polydopamine-based superhydrophobic paper prepared in Example 1 at a magnification of 10 μm, where h is the SEM image at a magnification of 10 μm, i is the total element EDS image of the sample in Example 1, and g~m are the EDS images of the C, N, O and Si elements of the sample in Example 1, respectively.

[0023] Figure 5 This is the total spectrum of the SEM-EDS distribution diagram of the superhydrophobic paper based on polydopamine prepared in Example 1.

[0024] Figure 6 These are infrared spectra of the unmodified filter paper prepared in Comparative Example 1, the filter paper modified with a polydopamine intermediate layer prepared in Comparative Example 4, and the superhydrophobic paper based on polydopamine prepared in Example 1.

[0025] Figure 7 These are XPS spectra of the unmodified filter paper prepared in Comparative Example 1, the filter paper modified with a polydopamine intermediate layer prepared in Comparative Example 4, and the superhydrophobic paper based on polydopamine prepared in Example 1.

[0026] Figure 8 These are XRD spectra of the unmodified filter paper prepared in Comparative Example 1, the filter paper modified with a polydopamine intermediate layer prepared in Comparative Example 4, and the superhydrophobic paper based on polydopamine prepared in Example 1.

[0027] Figure 9 a~c are the surface contact angles of the polydopamine-based superhydrophobic paper prepared in Example 1, Example 2, and Example 3, respectively.

[0028] Figure 10 In the figures a to c, the water drop anti-sticking of the polydopamine-based superhydrophobic paper prepared in Example 1, Example 2, and Example 3, respectively, each row from left to right is four representative pictures taken from the beginning to the end during the contact angle measurement.

[0029] Figure 11 a1~a4 and b1~b4 are different angles of the superhydrophobic paper based on polydopamine prepared in Example 1, and c1~c4 are different angles of the antifouling and self-cleaning optical pictures of the unmodified filter paper prepared in Comparative Example 1.

[0030] Figure 12 Figures a~d show the effects of different liquids on the surface of super-hydrophobic paper, respectively corresponding to the liquids milk, orange juice, water and soy sauce. Figure e shows the comparison of the effects of milk, orange juice, water and soy sauce on the surface of super-hydrophobic paper from left to right. DETAILED DESCRIPTION

[0031] The following is a detailed description of the technical solutions in the embodiments of the present invention, using preferred embodiments and accompanying drawings in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0032] It should be noted that all professional terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be purchased from the market or prepared by existing methods.

[0033] Example 1 A method for preparing super-hydrophobic paper based on polydopamine comprises the following steps: (1) First, cut the chemical analysis filter paper into several pieces of 3×3 cm 2 The natural filter paper was obtained by dissolving 0.02 g of dopamine in 40 mL of hydrochloric acid buffer to obtain a dopamine hydrochloric acid solution with a concentration of 0.5 mg / mL. The natural filter paper was then used as a substrate and immersed in the prepared dopamine hydrochloric acid solution. The solution was allowed to react at 25°C for 12 h. Through the oxidative self-polymerization of dopamine, a filter paper modified with a polydopamine intermediate layer was obtained. (2) 0.5 mL of dodecyltrimethoxysilane and 50 mL of ethanol solution were measured and mixed to obtain hexadecyltrimethoxysilane ethanol solution. The filter paper modified with the polydopamine intermediate layer was immersed in the dodecyltrimethoxysilane ethanol solution and reacted at 25 °C for 1 h for hydrophobic modification. The filter paper was taken out and dried at 80 °C to obtain superhydrophobic paper based on polydopamine.

[0034] Example 2 A method for preparing super-hydrophobic paper based on polydopamine comprises the following steps: (1) First, cut the chemical analysis filter paper into several pieces of 3×3 cm 2 The natural filter paper was obtained by dissolving 0.02 g of dopamine in 40 mL of hydrochloric acid buffer to obtain a dopamine hydrochloric acid solution with a concentration of 0.5 mg / mL. The natural filter paper was then used as a substrate and immersed in the prepared dopamine hydrochloric acid solution. The solution was allowed to react at 25°C for 8 h. Through the oxidative self-polymerization of dopamine, a filter paper modified with a polydopamine intermediate layer was obtained. (2) 0.3 mL of hexadecyltrimethoxysilane and 50 mL of ethanol solution were measured and mixed to obtain a hexadecyltrimethoxysilane ethanol solution. The filter paper modified with the polydopamine intermediate layer was immersed in the hexadecyltrimethoxysilane ethanol solution and reacted at 25 °C for 1 h for hydrophobic modification. The filter paper was taken out and dried at 80 °C to obtain a superhydrophobic paper based on polydopamine.

[0035] Example 3 A method for preparing super-hydrophobic paper based on polydopamine comprises the following steps: (1) First, cut the chemical analysis filter paper into several pieces of 3×3cm 2 The natural filter paper was obtained by dissolving 0.02 g of dopamine in 40 mL of hydrochloric acid buffer to obtain a 0.5 mg / mL dopamine hydrochloric acid solution. The natural filter paper was then used as a substrate and immersed in the prepared dopamine hydrochloric acid solution. The solution was allowed to react at 25°C for 8 h. The dopamine was oxidized and self-polymerized to obtain a filter paper modified with a polydopamine intermediate layer. (2) 0.25 mL of octadecyltrimethoxysilane and 50 mL of ethanol solution were measured and mixed to obtain octadecyltrimethoxysilane ethanol solution. The filter paper modified with the polydopamine intermediate layer was immersed in the octadecyltrimethoxysilane ethanol solution and reacted at 25 °C for 1 h for hydrophobic modification. The filter paper was taken out and dried at 80 °C to obtain superhydrophobic paper based on polydopamine.

[0036] Example 4 A method for preparing super-hydrophobic paper based on polydopamine comprises the following steps: (1) First, cut the chemical analysis filter paper into several pieces of 3×3cm 2 The natural filter paper was obtained by dissolving 0.02 g of dopamine in 40 mL of hydrochloric acid buffer to obtain a 0.5 mg / mL dopamine hydrochloric acid solution. The natural filter paper was then used as a substrate and immersed in the prepared dopamine hydrochloric acid solution. The solution was allowed to react at 25°C for 24 h. The dopamine was oxidized and self-polymerized to obtain a filter paper modified with a polydopamine intermediate layer. (2) 0.25 mL of octadecylamine and 50 mL of ethanol solution were measured and mixed to obtain an octadecylamine ethanol solution. The filter paper modified with the polydopamine intermediate layer was then immersed in the octadecylamine ethanol solution and reacted at 25 °C for 0.5 h for hydrophobic modification. The filter paper was taken out and dried at 80 °C to obtain a superhydrophobic paper based on polydopamine.

[0037] Example 5 A method for preparing super-hydrophobic paper based on polydopamine comprises the following steps: 1) First, cut the chemical analysis filter paper into several pieces of 3×3cm 2The natural filter paper was obtained by dissolving 0.02 g of dopamine in 40 mL of hydrochloric acid buffer to obtain a 0.5 mg / mL dopamine hydrochloric acid solution. The natural filter paper was then used as a substrate and immersed in the prepared dopamine hydrochloric acid solution. The solution was allowed to react at 25°C for 8 h. The dopamine was oxidized and self-polymerized to obtain a filter paper modified with a polydopamine intermediate layer. (2) 0.5 mL of hexadecylamine solution and 50 mL of ethanol solution were measured and mixed to obtain a hexadecylamine ethanol solution. The filter paper modified with the polydopamine intermediate layer was then immersed in the hexadecylamine ethanol solution and reacted at 25 °C for 0.5 h for hydrophobic modification. The filter paper was taken out and dried at 80 °C to obtain a superhydrophobic paper based on polydopamine.

[0038] Example 6 A method for preparing super-hydrophobic paper based on polydopamine comprises the following steps: 1) First, cut the chemical analysis filter paper into several pieces of 3×3 cm 2 The natural filter paper was obtained by dissolving 0.02 g of dopamine in 40 mL of hydrochloric acid buffer to obtain a 0.5 mg / mL dopamine hydrochloric acid solution. The natural filter paper was then used as a substrate and immersed in the prepared dopamine hydrochloric acid solution. The solution was allowed to react at 25°C for 6 h. The dopamine was oxidized and self-polymerized to obtain a filter paper modified with a polydopamine intermediate layer. (2) 0.25 mL of tetradecylamine and 50 mL of ethanol solution were measured and mixed to obtain a tetradecylamine ethanol solution. The filter paper modified with the polydopamine intermediate layer was immersed in the tetradecylamine ethanol solution and reacted at 25 °C for 0.5 h for hydrophobic modification. The filter paper was taken out and dried at 80 °C to obtain a superhydrophobic paper based on polydopamine.

[0039] Comparative Example 1 The preparation method of unmodified filter paper comprises the following steps: Cut the chemical analysis filter paper into several pieces of 3×3 cm 2 The paper sample was obtained to obtain unmodified filter paper.

[0040] Comparative Example 2 A method for preparing filter paper modified with a polydopamine intermediate layer (filter paper@PDA) comprises the following steps: First, cut the chemical analysis filter paper into several pieces of 3×3 cm 2 The natural filter paper was obtained by dissolving 0.02 g of dopamine in 40 mL of hydrochloric acid buffer to obtain a dopamine hydrochloric acid solution with a concentration of 0.5 mg / mL. The natural filter paper was then used as a substrate and immersed in the prepared dopamine hydrochloric acid solution. The solution was allowed to react at 25°C for 6 hours. The filter paper modified with a polydopamine intermediate layer was obtained through dopamine oxidative self-polymerization.

[0041] Comparative Example 3 A method for preparing filter paper modified with a polydopamine intermediate layer (filter paper@PDA) comprises the following steps: First, cut the chemical analysis filter paper into several pieces of 3×3 cm 2 The natural filter paper was obtained by dissolving 0.02 g of dopamine in 40 mL of hydrochloric acid buffer to obtain a 0.5 mg / mL dopamine hydrochloric acid solution. The natural filter paper was then used as a substrate and immersed in the prepared dopamine hydrochloric acid solution. The solution was allowed to react at 25°C for 8 h. The dopamine was oxidized and self-polymerized to obtain a filter paper modified with a polydopamine intermediate layer. Comparative Example 4 First, cut the chemical analysis filter paper into several pieces of 3×3 cm 2 The natural filter paper was obtained by dissolving 0.02 g of dopamine in 40 mL of hydrochloric acid buffer to obtain a 0.5 mg / mL dopamine hydrochloric acid solution. The natural filter paper was then used as a substrate and immersed in the prepared dopamine hydrochloric acid solution. The solution was allowed to react at 25°C for 12 h. The dopamine was oxidized and self-polymerized to obtain a filter paper modified with a polydopamine intermediate layer. Result Analysis Figure 1 In the figure, a1-a3 are SEM images of the original filter paper fibers prepared in comparative example 1 of the present invention at different magnifications. It can be seen from the figure that the surface of the original unmodified filter paper is relatively smooth, has a flat structure, and has some wrinkles, indicating that it is conducive to the self-polymerization of dopamine on the surface to form polydopamine and deposit on the fiber surface.

[0042] Figure 2 The SEM images of the filter paper modified with the polydopamine intermediate layer prepared in Comparative Examples 2-4 at different magnifications, wherein b1 to b3 are samples of Comparative Example 2, c1 to c3 are samples of Comparative Example 3, and d1 to d3 are samples of Comparative Example 4. From the figure, it can be seen that the dopamine polymer particles are tightly coated on the surface of the filter paper fibers to form a micro-nano rough structure. The comparison of the three groups can be concluded Figure 2 d. The dopamine polymer particles are more densely distributed and more uniform. Therefore, it can be concluded that the surface roughness of the polydopamine-modified filter paper prepared by soaking in dopamine for 12 h is higher, which is more conducive to the preparation of superhydrophobic paper.

[0043] Figure 3The following are SEM images of the super-hydrophobic polydopamine-based paper prepared in Examples 1, 2, and 3 at different magnifications. Figures e1-e3 are from Example 1, f1-f3 are from Example 2, and g1-g3 are from Example 3. As can be seen from the images, after the hydrophobic treatment, the surface of the dopamine particles is coated with a polymer film. This polymer film is the long-chain silane coupling agent hexadecyltrimethylsilane, demonstrating successful hydrophobicization, reducing the surface energy of the paper and imparting a certain degree of hydrophobicity. This is also the reason why the paper exhibits super-hydrophobic properties after hydrophobic treatment.

[0044] Figure 4 This is the SEM-EDS image of the polydopamine-based superhydrophobic paper prepared in Example 1 at a magnification of 10 μm, where h is the SEM image at a magnification of 10 μm, i is the total element EDS image of the sample in Example 1, and g~m are the EDS images of the C, N, O and Si elements of the sample in Example 1, respectively. It can be seen from the figure that the surface of the sample presents a continuous film layer structure, and the overall morphology flatness (Ra≈150 nm) indicates that the polydopamine intermediate layer provides effective support for subsequent hydrophobic modification.

[0045] Figure 5 This is the total spectrum of the SEM-EDS distribution map of the superhydrophobic paper based on polydopamine prepared in Example 1. It can be seen from the figure that the Si element (1.74 keV characteristic peak) is evenly distributed, with an atomic percentage of 8.7%, confirming that hexadecyltrimethylsilane is successfully bonded to the surface of the substrate.

[0046] Figure 6 The infrared spectra of the unmodified filter paper prepared in Comparative Example 1, the filter paper modified with the polydopamine intermediate layer prepared in Comparative Example 4, and the superhydrophobic paper based on polydopamine prepared in Example 1 are shown in FIG. 1 . In the FTIR spectrum of the filter paper modified with the polydopamine intermediate layer prepared in Comparative Example 4 (filter paper @ PDA), the peak at 1510 cm -1 (NH bending vibration of PDA), 1290 cm -1 Typical PDA characteristic peaks were observed at the (CN stretching) positions, proving that PDA was successfully deposited on the filter paper surface. In the FTIR spectrum of the polydopamine-based superhydrophobic paper (filter paper@PDA@HDTMS) prepared in Example 1, the peaks at 2920 / 2850 cm -1 (-CH2- asymmetric / isotropic stretching vibration of HDTMS), 1080 cm -1 (Si-O-Si stretching vibration), indicating that the long silane chains were effectively grafted.

[0047] Figure 7The XPS spectra of the unmodified filter paper prepared in Comparative Example 1, the filter paper modified with a polydopamine intermediate layer prepared in Comparative Example 4, and the superhydrophobic paper based on polydopamine prepared in Example 1. From the XPS spectrum of the unmodified filter paper, it can be found that it is mainly composed of two chemical elements, C and O, with binding energy peaks of 284.8 eV and 286.3 eV, respectively. The newly added CN peak (285.5 eV) and N1s signal (399.8 eV) of the filter paper modified with a polydopamine intermediate layer confirm the successful deposition of polydopamine; the filter paper modified with a polydopamine intermediate layer has a newly added Si2p peak with a peak value of 102 eV, indicating that the silane group (Si-O-Si or Si-C) of HDTMS has been successfully grafted to the PDA-modified surface.

[0048] Figure 8 The XRD spectra of the unmodified filter paper prepared in Comparative Example 1, the filter paper modified with a polydopamine intermediate layer prepared in Comparative Example 4, and the superhydrophobic paper based on polydopamine prepared in Example 1 showed typical peaks of cellulose fibers in the unmodified filter paper at 2θ values ​​of 14.9°, 16.5°, and 22.6°; the intensity of the characteristic peak of cellulose in the filter paper modified with a polydopamine intermediate layer was reduced, indicating that the PDA amorphous layer covered the fiber surface, and the spectrum of the superhydrophobic paper based on polydopamine (filter paper@PDA@HDTMS) showed a newly added broadened peak (2θ≈20°), corresponding to the amorphous siloxane structure of HDTMS, indicating that the modification did not destroy the fiber crystal skeleton.

[0049] Figure 9 Figures a to c are the surface contact angles of the polydopamine-based super-hydrophobic paper prepared in Examples 1, 2, and 3. As can be seen from the figure, the experimentally measured contact angle is around 152°, meeting the super-hydrophobic standard. When the liquid contact angle is greater than 150°, it exhibits super-hydrophobicity and is considered a super-hydrophobic surface. The larger the contact angle, the better the super-hydrophobic effect. It can be concluded that the hydrophobic paper prepared in Example 1 has the best super-hydrophobic effect, which is consistent with the SEM analysis results.

[0050] Figure 10 Figures a through c show four representative images from left to right during the contact angle measurement process, taken from the beginning to the end. Specifically, they show the water droplet anti-adhesion performance of the polydopamine-based superhydrophobic paper prepared in Examples 1, 2, and 3. Figure a shows that the water droplet on the syringe needle does not adhere to the superhydrophobic paper prepared in Example 1 after contact. In contrast to Figures b and c, the water droplet adhesion experiment was able to be removed from the syringe in both cases. This demonstrates that the superhydrophobic paper prepared in Example 1 exhibits superior hydrophobic anti-adhesion performance compared to the superhydrophobic papers prepared in Examples 2 and 3.

[0051] Figure 11In the figure, a1-a4 and b1-b4 are the antifouling self-cleaning optical pictures of the super-hydrophobic paper based on polydopamine prepared in Example 1 and c1-c4 are the non-modified filter paper prepared in Comparative Example 1. In order to observe the self-cleaning performance of the super-hydrophobic paper, a piece of soil was scattered on the surface of the filter paper as a pollutant. Figure 11 The dirt in areas a1-a4 was easily washed away by the rolling water droplets, leaving behind a completely clean superhydrophobic paper. This indicates that the obtained paper has excellent self-cleaning and antifouling properties. Figure 11 In Figures c1 to c4, the unmodified filter paper was wetted and stained by orange juice. Figure 11 Figures b1-b4 show that the polydopamine-based superhydrophobic paper, when soaked in orange juice, was not wetted or stained, demonstrating excellent self-cleaning capabilities. The experiment demonstrates that the polydopamine-based superhydrophobic paper prepared in Example 1 prevents contaminants from adhering to the paper surface, thereby achieving both anti-fouling and self-cleaning properties.

[0052] Figure 12 Figures a through d show the effects of different liquids (milk, orange juice, water, and soy sauce) on the super-hydrophobic paper surface of Example 3. Figures a through d correspond to milk, orange juice, water, and soy sauce, respectively. Figure e shows, from left to right, a comparison of the effects of milk, orange juice, water, and soy sauce on the super-hydrophobic paper surface. As can be seen from the figures, each aqueous liquid exhibits a nearly spherical, non-wetting morphology on the surface of the super-hydrophobic paper of Example 3. This observation demonstrates that the resulting super-hydrophobic paper surface possesses super-hydrophobic properties.

[0053] It should be noted that when numerical ranges are mentioned in the present invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints may be selected. Since the steps and methods used are the same as those in the embodiments, in order to avoid redundancy, the present invention describes preferred embodiments. Although preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they understand the basic inventive concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0054] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for preparing super-hydrophobic paper based on polydopamine, characterized in that, The following steps are involved: Using natural filter paper as the substrate, it was immersed in a dopamine hydrochloric acid solution, and the dopamine was oxidized and self-polymerized to obtain a filter paper modified with a polydopamine intermediate layer; The filter paper modified with the polydopamine intermediate layer was immersed in an ethanol solution of a long carbon chain silane coupling agent for hydrophobic modification to obtain a superhydrophobic paper based on polydopamine.

2. the super-hydrophobic paper preparation method based on polydopamine according to claim 1, is characterized in that, The concentration of dopamine hydrochloric acid solution is 0.5 mg / mL-2 mg / mL.

3. the super-hydrophobic paper preparation method based on polydopamine according to claim 1, is characterized in that, The natural filter paper is soaked in the dopamine hydrochloric acid solution for 6 hours to 12 hours.

4. the super-hydrophobic paper preparation method based on polydopamine according to claim 1, is characterized in that, In the long carbon chain silane coupling agent solution, the volume ratio of the long carbon chain silane coupling agent to ethanol is 0.5:100-1:

100.

5. the super-hydrophobic paper preparation method based on polydopamine according to claim 1, is characterized in that, The long carbon chain silane coupling agent is a long carbon chain silane coupling agent or a long carbon chain alkylamine.

6. the super-hydrophobic paper preparation method based on polydopamine according to claim 5, is characterized in that, The long carbon chain silane coupling agent or long carbon chain alkylamine is one or more of dodecyltrimethoxysilane, hexadecyltrimethoxysilane, octadecyltrimethoxysilane, dodecylamine, hexadecylamine and octadecylamine.

7. The super-hydrophobic paper preparation method based on polydopamine according to claim 1, wherein The hydrophobic modification temperature is room temperature, and the time is: 0.5h-1h.

8. a super-hydrophobic paper prepared by the preparation method described in any one of claims 1-7.

9. super hydrophobic paper according to claim 8, characterized in that, The water contact angle is ≥150° and the surface has a micro-nano composite rough structure.

10. Use of the super-hydrophobic paper according to claim 8 in food packaging, antifouling materials or moisture-proof fields of electronic devices.

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