A gas-liquid interface metal-polyphenol network film and a preparation method thereof

Abstract

The application relates to a kind of metal-polyphenol network films at gas-liquid interface and preparation method thereof.In existing research,there is still the technical defect that the assembly process regulation range of metal-polyphenol network film is limited.The application discloses a kind of preparation method of metal-polyphenol network film,which utilizes volatile base to slowly gradually improve the pH of metal ion and polyphenol mixed solution,realizes the kinetic regulation of metal ion and polyphenol assembly speed.The film prepared by the above-mentioned gas-liquid interface can be transferred to different substrates, and the film can be used to adjust surface constrained reaction, and give the film different structure and function. The method has universality and can be used in invariable metal ion system, macromolecular polyphenol system and oxygen sensitive system.

Description

Technical Field

[0001] This invention belongs to the field of metal-polyphenol thin film technology, and specifically relates to a method for preparing a gas-liquid interface metal-polyphenol network thin film. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Metal-polyphenol networks are supramolecular networks formed by the self-assembly of metal ions and polyphenols. Polyphenols are naturally occurring bioactive substances that endow metal-polyphenol network materials with excellent bioactivity. A wide variety of metal ions and polyphenols can assemble into metal-polyphenol networks, which can be fabricated into thin film materials with different compositions, sizes, morphologies, and functions. Metal-polyphenol network thin films possess excellent properties such as pH responsiveness, biocompatibility, and widespread adhesion, showing great promise for applications in the biomedical and environmental fields.

[0004] Researchers have developed various techniques for preparing metal-polyphenol network thin films, such as discrete methods, layer-by-layer self-assembly, and oxidation-mediated methods. However, existing techniques still have many problems. Discrete methods are too fast to allow for precise control of film thickness and properties; layer-by-layer self-assembly is complex and has limited thickness control; oxidation-mediated methods lack universality and cannot be used for systems with constant valence metal ions, large-molecule polyphenol systems, or oxygen-sensitive systems.

[0005] Chinese patent document CN115282778A discloses a method for preparing and applying a metal-polyphenol network thin film. This method uses a porous supporting membrane as a physical barrier, adding an aqueous polyphenol solution to one side and a metal salt solution to the other. A metal-polyphenol network is assembled on the surface of the porous supporting membrane using a relative diffusion process, thus preparing an ultrathin metal-polyphenol network separation membrane. This preparation method relies on a specific diffusion device, increasing the preparation cost. Furthermore, the structure of the porous supporting membrane also limits the construction of the metal-polyphenol network thin film, thereby limiting some applications of the film. Summary of the Invention

[0006] In view of the above-mentioned technical background, the purpose of this invention is to provide a method for preparing metal-polyphenol network films that can flexibly control the structure and properties. In the volatile alkali-mediated film synthesis scheme of this invention, a network film can be rapidly formed directly at the gas-liquid interface, and the thickness of the network film is adjustable.

[0007] To this end, the present invention first provides a method for preparing a gas-liquid interface metal-polyphenol network thin film, comprising the following steps: mixing polyphenols with metal ions to obtain a precursor solution, placing the precursor solution and an alkaline solution together in a sealed container and allowing them to stand for a period of time until a thin film is formed at the gas-liquid interface of the precursor solution, and transferring the thin film to a substrate according to the application purpose.

[0008] The above preparation method utilizes alkaline gas diffusion to prepare a multifunctional metal-polyphenol network film. The alkaline solution and the precursor solution are reacted independently in sealed containers. This invention has found that by slowly increasing the pH of the precursor solution using the alkaline gas emitted from the alkaline reagent, the assembly rate of metal ions and polyphenols can be kinetically controlled. This allows for the formation of a continuous film at the gas-liquid interface, extending the reaction time and correspondingly increasing the film thickness. The film thickness can also be flexibly controlled by altering the concentration of the precursor solution, the concentration of the alkaline solution, and the distance between the alkaline solution and the precursor solution. This film can also be transferred to different substrates to obtain films with different properties and functions. Furthermore, reactions can continue to occur on this film, endowing it with different structures and functions. According to the verification of this invention, the substrate can be a solid-phase planar substrate or a liquid-phase substrate. By changing the substrate, the metal-polyphenol network film can acquire different properties and achieve different applications.

[0009] Furthermore, in the scheme using a liquid phase substrate, after the aforementioned film is transferred to the liquid phase substrate, it can continue to react with the components in the liquid phase substrate, and the production personnel can select the liquid phase substrate according to the loading target of the network film.

[0010] Secondly, the present invention provides a metal-polyphenol network film obtained by the above preparation method.

[0011] Polyphenolic compounds possess properties such as oxidative polymerization, coordination complexation, adhesion, biocompatibility, free radical scavenging, and light absorption, which enable this metal-polyphenol network film to have wide applications in fields such as biomedicine, agriculture, sensing, catalysis, separation, drug delivery, antioxidant and antibacterial coatings.

[0012] The beneficial effects of one or more of the above technical solutions are:

[0013] This invention uses polyphenols and metal salts as raw materials and water as a solvent to prepare metal-polyphenol network films. The materials are widely available and environmentally friendly. The preparation method of this invention is simple and convenient, requiring no complex equipment. Furthermore, the thickness, morphology, and other physicochemical properties of the film can be controlled by changing various factors such as the concentration of the precursor solution, the concentration of the alkaline solution, the diffusion time, and the diffusion distance. Simultaneously, this film prepared at the gas-liquid interface can be easily transferred to various substrates for application. The planar metal-polyphenol network film prepared by this invention can be used to regulate surface-constrained reactions. The prepared film has a Janus bifacial structure, thereby endowing the film with different structures and functions. The metal-polyphenol network film preparation method of this invention is universal and applicable to various metal ion and bimetallic systems. Attached Figure Description

[0014] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0015] Figure 1 This is a schematic diagram of the reaction process for preparing the metal-polyphenol network thin film in Example 1;

[0016] Figure 2 The image shows the metal-polyphenol network film prepared at the gas-liquid interface in Example 1.

[0017] Figure 3 An atomic force microscope (AFM) image of the metal-polyphenol network film prepared in Example 1;

[0018] Figure 4 The growth curve of the metal-polyphenol network film prepared in Example 2 is shown.

[0019] Figure 5 Images of the metal-polyphenol network film coated on different substrates on the planar substrate prepared in Example 3;

[0020] Figure 6 Scanning electron microscope (SEM) images of Janus films prepared by surface confinement reaction on the metal-polyphenol network films prepared in Examples 4 and 5;

[0021] Figure 7 An atomic force microscope (AFM) image of the metal-polyphenol network film prepared in Comparative Example 1. Detailed Implementation

[0022] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0023] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0024] As described in the background section, existing methods for preparing metal-polyphenol network films have limited control over the thickness and properties of the films. This invention introduces an alkaline reagent during the reaction of polyphenols with metal ions. By using the alkaline volatile reagent, the environment for constructing the metal-polyphenol network film is slowly improved. By controlling the substrate of the network film, film materials with different configurations and applications can be obtained, greatly improving the flexibility of metal-polyphenol network film preparation.

[0025] In a first aspect, the present invention provides a method for preparing a metal-polyphenol network thin film at a gas-liquid interface, comprising the following steps: mixing polyphenols with metal ions to obtain a precursor solution; placing the precursor solution and an alkaline solution together in a sealed container and allowing them to stand for a period of time until the solution forms a thin film; and transferring the thin film to a substrate to obtain the film.

[0026] The above method is applicable to almost all polyphenol compounds and metal ion systems, and is a universal preparation process. Applicable polyphenols include phenol, catechol, resorcinol, hydroquinone, pyrogallol, gallic acid, tannic acid, or epigallocatechin gallate; preferably, one or more combinations of gallic acid, tannic acid, and epigallocatechin gallate are preferred.

[0027] Suitable metal ions include zinc ions, copper ions, cobalt ions, nickel ions, cadmium ions, manganese ions, molybdenum ions, aluminum ions, vanadium ions, iron ions, cadmium ions, rhodium ions, ruthenium ions, zirconium ions, cerium ions, europium ions, gadolinium ions, and terbium ions. These metal ions can be derived from metal salts, including ZnSO4•7H2O, CuCl2•4H2O, Co(NO3)2·6H2O, NiCl2·6H2O, CdCl2, MnCl2·4H2O, Mo2(OCOCH3)4, AlCl3·6H2O, VCl3, FeCl3·6H2O, CrCl3·H2O, RhCl3, RuCl3, ZrCl4, CeCl3·7H2O, EuCl3·6H2O, and GdCl3·6H2O. 、 One or more of TbCl3·6H2O.

[0028] The alkaline solution is preferably a volatile alkaline solution, such as one of ammonia, ethylenediamine, butanediamine, pentanediamine, triethylamine, pyridine, pyrimidine, pyrazine, oxazole, thiazole, or pyridazine solutions, more preferably one of ammonia, ethylenediamine, butanediamine, pentanediamine, triethylamine, or pyridine solutions; the concentration of the alkaline solution is 5-50%, preferably 5-10%.

[0029] In the precursor solution, the polyphenol concentration is 0.1–100 mg / mL, preferably 5–50 mg / mL; and the metal salt concentration is 1–100 mmol / L, preferably 3–50 mmol / L.

[0030] In one embodiment of the above preparation method, the substrate is a solid-phase substrate, including one of silicon wafers, glass, mica sheets, gold sheets, stainless steel substrates, polystyrene substrates, polymethyl methacrylate substrates, and polycarbonate substrates, preferably one of silicon wafers, gold sheets, and glass; in embodiments using solid-phase substrates, the specific steps of the preparation method are as follows:

[0031] The precursor solution and the alkaline solution are placed together in a sealed container and allowed to stand for a period of time until a thin film forms at the gas-liquid interface of the precursor solution. The film is then transferred to a solid substrate, flattened, and dried with an inert gas to obtain the film. The standing time is 3 min to 24 h, preferably 10 min to 15 h.

[0032] In one embodiment of the above preparation method, the substrate is a liquid phase substrate, and the Janus film prepared by this method is as follows: the precursor solution and the alkaline solution are placed together in a sealed container and left to stand for a period of time until a film is formed at the gas-liquid interface of the precursor solution. The film is then transferred to the liquid surface of the liquid phase substrate and spread flat. After reacting for a period of time, the film is obtained.

[0033] In a specific example, the liquid substrate is an 80-120 mM silver nitrate solution. After transferring the above-mentioned film to the silver nitrate solution and reacting for 2-4 hours, a metal-polyphenol network film with grown silver nanoparticles is obtained.

[0034] In another specific example, the liquid substrate is prepared by reacting cobalt nitrate (20-35 mg / mL) and 2-methylimidazole solution (60-80 mg / mL) to obtain a metal-polyphenol network film with ZIF-67 grown on it.

[0035] In a second aspect, the present invention provides a metal-polyphenol network film prepared by the method described in the first aspect.

[0036] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments and comparative examples.

[0037] Terminology Explanation:

[0038] The following terms in this application refer to a method of thin film transfer at the gas-liquid interface, combined with... Figure 1 show:

[0039] Stamping method: The transfer medium covers the film from above and downwards, thus "adhere" the film away. After the transfer, the side of the film that was originally in contact with the gas is close to the solid substrate for drying.

[0040] Extraction method: The transfer matrix is ​​extracted from below the membrane. After the transfer, the side of the membrane that was originally in contact with the gas remains in contact with the gas.

[0041] Example 1

[0042] A method for preparing a gas-liquid interface metal-polyphenol network thin film includes the following steps:

[0043] A precursor solution was prepared by dissolving 40 mg of tannic acid (TA) and 3.2 mg of copper chloride tetrahydrate in 2 mL of water. An alkaline solution was prepared by dissolving 200 μL of ammonia (NH3·H2O) in 2 mL of water. The petri dishes containing the precursor solution and the alkaline solution were placed together in a sealed beaker. After reacting for 10 min and 70 min, the thin film on the surface of the precursor solution was transferred to a silicon wafer using a stamping method. After drying with nitrogen, a Cu-TA thin film was obtained, named NH3-Cu-TA thin film.

[0044] Example 2

[0045] A method for preparing a gas-liquid interface metal-polyphenol network thin film includes the following steps:

[0046] A precursor solution was prepared by dissolving 5 mg of tannic acid (TA) and 0.4 mg of copper chloride tetrahydrate in 2 mL of water. An alkaline solution was prepared by dissolving 200 μL of ethylenediamine (EDA) in 2 mL of water. The petri dishes containing the precursor solution and the alkaline solution were placed together in a sealed beaker. After reacting for 0.2 h, 3 h, and 15 h, respectively, the thin film on the surface of the precursor solution was transferred onto a silicon wafer using a stamping method. After drying under nitrogen, a Cu-TA thin film was obtained, named the EDA-Cu-TA thin film.

[0047] Example 3

[0048] A method for preparing a gas-liquid interface metal-polyphenol network film is identical to that of Example 1, except that the substrate is replaced with a polycarbonate substrate, glass, gold sheet, stainless steel substrate, polystyrene substrate, or polymethyl methacrylate substrate, respectively. Other steps and conditions are the same as in Example 1, and all methods can successfully prepare the metal-polyphenol network film material.

[0049] Example 4

[0050] A method for preparing Janus films by surface-confined reaction on metal-polyphenol network films prepared at the gas-liquid interface includes the following steps:

[0051] A precursor solution was prepared by dissolving 40 mg of tannic acid (TA) and 3.2 mg of copper chloride tetrahydrate in 2 mL of water. An alkaline solution was prepared by dissolving 200 μL of ammonia (NH3·H2O) in 2 mL of water. The petri dishes containing the precursor solution and the alkaline solution were placed together in a sealed beaker. After reacting for 10 min, the film on the surface of the precursor solution was transferred to 100 mM silver nitrate solution using an extraction method. After reacting for 3 h, an Ag-Cu-TA film was obtained.

[0052] Example 5

[0053] A method for preparing Janus films by surface-confined reaction on metal-polyphenol network films prepared at the gas-liquid interface includes the following steps:

[0054] A precursor solution was prepared by dissolving 40 mg of tannic acid (TA) and 3.2 mg of copper chloride tetrahydrate in 2 mL of water. An alkaline solution was prepared by dissolving 200 μL of ammonia (NH3·H2O) in 2 mL of water. The petri dishes containing the precursor solution and the alkaline solution were placed together in a sealed beaker. After reacting for 10 min, the film on the surface of the precursor solution was transferred to a solution of cobalt nitrate hexahydrate (29.2 mg / mL) and hexadecyltrimethylammonium bromide (1 mg / mL) using an extraction method. After reacting for 15 min, the film was then transferred to a solution of 2-methylimidazole (70 mg / mL) using another extraction method and reacted for 1 h to obtain the ZIF-67-Cu-TA film.

[0055] Comparative Example 1

[0056] To compare the controllability of the volatile alkali diffusion method and the discrete method on the metal-polyphenol network assembly process, a method for preparing a metal-polyphenol network coating on a planar substrate is provided, comprising the following steps:

[0057] A precursor solution was prepared by dissolving 40 mg of tannic acid (TA) and 3.2 mg of copper chloride tetrahydrate in 2 mL of water. The silicon wafer was then immersed in the precursor solution, and the pH of the precursor solution was adjusted to 8 with sodium hydroxide solution. The reaction was carried out for 10 min. After washing with water three times and drying with nitrogen, the metal-polyphenol network coating material was obtained.

[0058] Detection of metal-polyphenol network films prepared at the gas-liquid interface

[0059] (1) The thin film material obtained in Example 1 was subjected to AFM testing. The AFM image is shown below. Figure 3 As shown, a coating thickness of approximately 42 nm was formed after 10 minutes, and approximately 135 nm was formed after 70 minutes, demonstrating the successful formation of the ammonia-mediated metal-polyphenol network film. Existing research on the synthesis of metal-polyphenol network films typically struggles to control the thickness; the above results effectively confirm that the method of this invention can adjust the thickness. Furthermore, through repeated verification by this invention, the film thickness in the scheme using a volatile alkaline solution-mediated film synthesis shows a strong correlation with reaction time, alkaline solution concentration, and the distance between the alkaline solution and the precursor solution. Extending the time both solutions remain in a sealed container, increasing the alkaline solution concentration, and reducing the distance between the precursor solution and the alkaline solution can effectively improve the rate and thickness of network film formation.

[0060] (2) Meanwhile, the AFM test results of the thin film material in Comparative Example 1 are as follows: Figure 7 As shown, after 10 minutes of reaction, only some large metal-polyphenol network complexes adhered, and no continuous film was formed. This comparative result indicates that the method of directly adding alkaline solution to the precursor solution to increase the pH cannot achieve flexible control of the pH environment in the reaction system, resulting in the metal ions and polyphenols assembling too quickly, making it impossible to achieve kinetic control of the assembly process, and thus making it difficult to achieve the desired film assembly effect.

[0061] (3) The thin film material obtained in Example 2 was subjected to AFM testing. The thickness of the thin film material obtained after 0.2h, 3h, and 15h of reaction was measured, and a thickness versus time curve was plotted, as shown below. Figure 4 As shown, the film thickness can be controlled within the range of 40 nm to 700 nm. This demonstrates the successful formation of the ethylenediamine-mediated metal-polyphenol network film.

[0062] Furthermore, the above results also confirm that the thickness of the metal-polyphenol network film increases continuously with the extension of reaction time. In actual production, technicians can control the film growth process by adjusting factors such as reaction time, distance between precursor solution and alkaline solution, concentration of precursor solution and concentration of alkaline solution according to the usage requirements.

[0063] Janus film detection

[0064] (1) The Janus film obtained in Example 4 was subjected to SEM testing. The SEM images are shown below. Figure 6 As shown, Example 4 successfully grew Ag nanoparticles on one side of a metal-polyphenol network film.

[0065] (2) The Janus film obtained in Example 5 was subjected to SEM testing. The SEM images are shown below. Figure 6 As shown, Example 5 demonstrates the successful growth of ZIF-67 nanoparticles on one side of a metal-polyphenol network film.

[0066] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a gas-liquid interface metal-polyphenol network thin film, characterized in that, The process includes the following steps: polyphenols are mixed with metal ions to obtain a precursor solution; the precursor solution and a volatile alkaline solution are placed together in a sealed container and left to stand for a period of time to allow the gas volatilized from the alkaline solution to diffuse into the precursor solution; a thin film is formed at the gas-liquid interface of the precursor solution; and the thin film is transferred to a solid substrate or a liquid substrate to obtain the product. The precursor solution contains polyphenols at a concentration of 0.1–100 mg / mL and metal ions at a concentration of 1–100 mmol / L. The alkaline solution has a concentration of 5-50% and is selected from one of the following: ammonia, ethylenediamine, butanediamine, pentanediamine, triethylamine, pyridine, pyrimidine, pyrazine, oxazole, thiazole, and pyridazine solutions. A Janus film is prepared by transferring the film to a liquid substrate. The specific steps are as follows: the precursor solution and the alkaline solution are placed together in a sealed container and left to stand for a period of time until a film is formed at the gas-liquid interface of the precursor solution. The film is then transferred to the liquid surface of the liquid substrate and spread out. After reacting for a period of time, the film is obtained.

2. The method for preparing the gas-liquid interface metal-polyphenol network thin film as described in claim 1, characterized in that, The polyphenols are selected from phenol, catechol, resorcinol, hydroquinone, pyrogallol, gallic acid, tannic acid, or epigallocatechin gallate.

3. The method for preparing the gas-liquid interface metal-polyphenol network thin film as described in claim 1, characterized in that, The metal ions are selected from zinc ions, copper ions, cobalt ions, nickel ions, cadmium ions, manganese ions, molybdenum ions, aluminum ions, vanadium ions, iron ions, rhodium ions, ruthenium ions, zirconium ions, cerium ions, europium ions, gadolinium ions, or terbium ions.

4. The method for preparing the gas-liquid interface metal-polyphenol network thin film as described in claim 3, characterized in that, The metal ions are derived from metal salts, including ZnSO4. 7H2O, CuCl2 4H2O, Co(NO3)2 6 H2O, NiCl2 6 H2O, CdCl2, MnCl2 4H2O, Mo2(OCOCH3)4, AlCl3 6 H2O, VCl3, FeCl3 6H2O, CrCl3 H2O, RhCl3, RuCl3, ZrCl4, CeCl3 7H2O, EuCl3 6 H2O, GdCl3 6 H2O 、 TbCl3 One or more of 6 H2O.

5. The method for preparing the gas-liquid interface metal-polyphenol network thin film as described in claim 1, characterized in that, The alkaline solution is one of ammonia, ethylenediamine, butanediamine, pentanediamine, triethylamine, or pyridine solution, with a concentration of 5-10%.

6. The method for preparing the gas-liquid interface metal-polyphenol network thin film as described in claim 1, characterized in that, The solid substrate is selected from one of the following: silicon wafer, glass, mica sheet, gold sheet, stainless steel substrate, polystyrene substrate, polymethyl methacrylate substrate, and polycarbonate substrate.

7. The method for preparing the gas-liquid interface metal-polyphenol network thin film as described in claim 6, characterized in that, The preparation method using a solid-phase substrate involves the following specific steps: The precursor solution and the alkaline solution are placed together in a sealed container and allowed to stand for a period of time until a thin film forms at the gas-liquid interface of the precursor solution. The film is then transferred to a solid substrate, flattened, and dried with an inert gas to obtain the film. The standing time is 3 min to 24 h.

8. The method for preparing the gas-liquid interface metal-polyphenol network thin film as described in claim 1, characterized in that, The liquid substrate is an 80-120 mM silver nitrate solution. After the above film is transferred to the silver nitrate solution and reacted for 2-4 h, a metal-polyphenol network film with grown silver nanoparticles is obtained. Alternatively, the reaction is carried out in a liquid substrate consisting of a solution of 20–35 mg / mL cobalt nitrate and 60–80 mg / mL 2-methylimidazole to obtain a metal-polyphenol network film with ZIF-67 grown on it.

9. The metal-polyphenol network film prepared by the method according to any one of claims 1-8.

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