ZnO@PDA@Cu composite material and preparation method thereof

Abstract

This invention provides a ZnO@PDA@Cu composite material and its preparation method. The preparation method involves pre-constructing a polydopamine functional interface layer on the surface of zinc-containing inorganic particles, and then using the complexation and adsorption sites provided by the interface layer to load copper species. This effectively separates the interface construction process from the metal loading process, thereby improving the stability and uniformity of metal species loading and enhancing the controllability and repeatability of the preparation process.

Description

Technical Field

[0001] This invention relates to a composite material, and more particularly to a ZnO@PDA@Cu composite material and its preparation method. Background Technology

[0002] Zinc-containing inorganic particulate materials (such as zinc oxide) have been widely used to construct various composite functional materials due to their certain surface reactivity and good material availability. In practical applications, it is often necessary to introduce metal species or other functional components onto their surface to endow the materials with antibacterial, catalytic, or other functional properties. However, since the effective binding sites on the surface of zinc-containing inorganic particles are limited, and surface components are easily lost during repeated washing or separation, how to achieve stable loading and controllable fixation of metal species has always been a concern in related technical fields.

[0003] To improve the surface chemical properties of zinc-containing inorganic particles, various surface functionalization or interface layer construction methods have been introduced in this study. Among them, polydopamine (PDA) has been used to construct functional interface layers for inorganic materials due to its universal adhesion properties and rich functional group structure, aiming to improve the feasibility of subsequent loading or modification. However, in specific applications, different construction paths still show differences in the stability, uniformity, and process controllability of metal species loading.

[0004] Existing technical solutions include: (1) Direct impregnation load route: Zinc-containing inorganic particles are directly contacted with solutions of metal salts such as copper salts to achieve metal species loading through physical adsorption or surface deposition. The resulting composite material is then washed and dried. While this method is simple, the metal species loading primarily relies on weak adsorption or deposition, and the loading amount and uniformity are affected by the surface condition of the substrate. Consequently, the loading amount is prone to decrease during subsequent washing or separation processes.

[0005] (2) Surface modification followed by loading: Pretreatment of zinc-containing inorganic particles through polymer coating, silane coupling, or surface oxidation introduces functional groups before metal ion complexation or deposition loading. While this method improves loading capacity to some extent, interface layer construction and metal loading often occur simultaneously or coupled, lacking stepwise control over these processes. This limits the adjustable range of process conditions, makes it difficult to guarantee consistency between batches, and during repeated washing or separation, free metal ions and weakly bound species are not easily distinguished and removed, potentially leading to issues of weak metal species fixation and insufficient stability. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for preparing ZnO@PDA@Cu composite material. The method involves pre-constructing a polydopamine functional interface layer on the surface of zinc-containing inorganic particles, and then using the complexation and adsorption sites provided by the interface layer to load copper species, thereby achieving effective separation between the interface construction process and the metal loading process, improving the stability and uniformity of metal species loading, and enhancing the controllability and repeatability of the preparation process.

[0007] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: A method for preparing a ZnO@PDA@Cu composite material includes the following steps: S1. Add zinc-containing inorganic particles to buffer solution, stir at room temperature for 20-40 min, and then add alkaline adjuster to adjust the pH of the system to 7.0-7.5 to obtain zinc-containing inorganic particle suspension; S2. Add dopamine monomer to the zinc-containing inorganic particle suspension obtained in step S1, stir the reaction at room temperature for 22-26 hours to obtain a reaction solution, centrifuge the reaction solution to obtain a precipitate, wash the precipitate three times with deionized water and ethanol respectively, and dry it naturally at room temperature to obtain ZnO@PDA intermediate. S3. Add the ZnO@PDA intermediate obtained in step S2 to a copper salt aqueous solution and stir at room temperature for 10-14 hours to obtain a reaction solution. Centrifuge the reaction solution to obtain a precipitate. Wash the precipitate three times with deionized water and ethanol respectively, and then dry it naturally at room temperature to obtain the ZnO@PDA@Cu composite material.

[0008] Furthermore, in step S1 of the present invention, the zinc-containing inorganic particles are zinc oxide particles with an average particle size of 100 μm, the buffer solution is a Tris-HCl buffer solution with a pH value of 8.0-8.5, and the ratio of zinc-containing inorganic particles to Tris-HCl buffer solution is (0.5-2) g: 100 mL.

[0009] Furthermore, in step S1 of the present invention, the stirring speed at room temperature is 500-600 rpm.

[0010] Further, in step S1 of this invention, the alkalinity regulator is sodium carbonate, potassium carbonate, or ammonia solution with a mass fraction of 25%. Step S1 adjusts the system to a mild alkaline range suitable for the oxidative self-polymerization of dopamine, so as to avoid significant dissolution or structural damage of the zinc-containing inorganic particles. Under the above conditions, the zinc-containing inorganic particles form a uniformly dispersed system, with the particle surface fully exposed and maintaining good interfacial accessibility, thus becoming a stable inorganic substrate for the subsequent construction of the interface layer.

[0011] Further, in step S2 of this invention, the dopamine monomer is dopamine hydrochloride, and the ratio of dopamine monomer to the zinc-containing inorganic particle suspension obtained in step S1 is (0.2-1) g: 100 mL. Under alkaline conditions, the dopamine monomer undergoes an oxidative self-polymerization reaction, and relying on its universal adhesion properties, a polydopamine (PDA) interface layer is formed in situ on the surface of the zinc-containing inorganic particles. This interface layer is rich in catechol groups and amino functional groups, providing functional sites for the subsequent selective fixation of metal species. During this oxidative self-polymerization process, the system color gradually deepens.

[0012] Further, in step S2 of this invention, the stirring speed at room temperature is 500-600 rpm, the centrifugation speed is 10000-12000 rpm, the centrifugation time is 10-15 min, and the natural drying time at room temperature is 24 h. Washing the precipitate obtained by centrifugation removes unreacted dopamine monomers, free salts, and weakly bound substances. After separation and washing, a structurally stable ZnO@PDA intermediate with a polydopamine functional interface on its surface is obtained, providing an interfacial basis for subsequent copper species loading. This intermediate maintains a similar state in multiple repeated preparation processes, indicating that it has good stability and reproducibility.

[0013] Further, in step S3 of this invention, the concentration of the copper salt aqueous solution is 0.05-0.5 mol / L, and the copper salt is one of copper chloride, copper sulfate, or copper nitrate. The ratio of the ZnO@PDA intermediate obtained in step S2 to the copper salt aqueous solution is (2-3) g: 100 mL. Under the conditions of step S3, the Cu in the copper salt... 2+ Copper species are selectively immobilized on the surface of inorganic zinc-containing particles through complexation, adsorption, and / or deposition under interface induction with catechol groups and / or amine groups in the PDA interface layer. By separating the interface layer construction step from the copper species loading step, the risk of non-selective deposition in the loading process can be reduced and the controllability of the copper species immobilization process can be improved.

[0014] Further, in step S3 of this invention, the stirring speed at room temperature is 500-600 rpm, the centrifugation speed is 10000-12000 rpm, the centrifugation time is 10-15 min, and the natural drying time at room temperature is 24 h. Washing the precipitate obtained by centrifugation can remove unfixed free Cu. 2+ After separation and washing purification, a structurally stable ZnO@PDA@Cu composite material was obtained, in which copper species are stably fixed on the surface of zinc-containing inorganic particles through the PDA interface layer.

[0015] Another technical problem to be solved by the present invention is to provide a ZnO@PDA@Cu composite material prepared by the above preparation method.

[0016] Key aspects of this invention include: 1) A two-step preparation strategy that separates interface construction from metal loading This invention separates the construction steps of the polydopamine interface layer from the loading steps of copper species in terms of time and process, forming a two-step preparation strategy of "interface first, loading later". This avoids non-selective deposition of metal species during the interface formation stage and improves the controllability and stability of the metal loading process.

[0017] 2) The polydopamine interface layer serves as a functional intermediate layer between the inorganic substrate and copper species. The polydopamine interface layer of this invention constructs a stable complexing / adsorption interface between zinc-containing inorganic particles and copper species through its rich catechol groups and amine functional groups, thereby achieving selective fixation of copper species and effectively decoupling the characteristics of inorganic substrate from the metal loading process.

[0018] 3) Copper species immobilization based on interfacial interactions, rather than direct deposition or simple adsorption. During the loading process, copper species are immobilized on the surface of zinc-containing inorganic particles through complexation, adsorption, and / or interface-induced deposition with the polydopamine interface layer, thereby improving loading stability and reducing the risk of residual free metal ions.

[0019] 4) Conditional control and purification methods in conjunction with interface load strategies Based on the above core technical solutions, by loading under alkaline conditions and combining it with a washing and purification strategy, the loading state of copper species can be further stabilized and controlled.

[0020] Compared with the prior art, the present invention has the following beneficial effects: Compared to existing techniques that directly load zinc-containing inorganic particles into copper salt solutions without constructing a polydopamine interface layer, this invention pre-constructs a polydopamine functional interface layer on the surface of zinc-containing inorganic particles, separating the interface construction process from the copper species loading process. This introduces high-density and uniformly distributed complexation and adsorption sites on the material surface. Based on this interface structure, copper species are selectively immobilized preferentially through the polydopamine interface layer during loading, rather than relying on random adsorption or direct deposition on the substrate surface. Therefore, under the same washing conditions, it exhibits higher load retention and more uniform distribution characteristics. Simultaneously, the stepwise construction process, combined with a multi-step washing and purification strategy, helps reduce the residue of free copper ions and weakly bound compounds, thereby improving the repeatability and process stability of the material preparation process. Through the above technical solution, this invention achieves effective control of the copper species loading state without significantly increasing process complexity, providing a reliable material basis for the stable use of the composite material in antibacterial and other related applications. Attached Figure Description

[0021] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, do not constitute an undue limitation of the invention. In the drawings: Figure 1 The Raman spectrum of ZnO; Figure 2 The image shows the Raman spectrum of the ZnO@PDA intermediate obtained in Example 1 of this invention. Figure 3 The X-ray photoelectron spectroscopy of the ZnO@PDA@Cu composite material prepared in Example 1 of this invention; Figure 4 The zeta potential test results are shown for ZnO, the ZnO@PDA intermediate prepared in Example 1 of this invention, and the ZnO@PDA@Cu composite material. Detailed Implementation

[0022] The present invention will now be described in detail with reference to specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention. Example

[0023] The ZnO@PDA@Cu composite material was prepared according to the following steps: S1. Add zinc-containing inorganic particles to Tris-HCl buffer solution with pH 8.4 at a ratio of 1g:100mL, stir at room temperature at 500rpm for 30min, and then add an alkaline adjuster to adjust the pH of the system to 7.2 to obtain a zinc-containing inorganic particle suspension. The zinc-containing inorganic particles are zinc oxide particles with an average particle size of 100μm, and the alkaline adjuster is ammonia water with a mass fraction of 25%. S2. Add dopamine monomer to the zinc-containing inorganic particle suspension obtained in step S1 at a ratio of 0.5g:100mL, stir at room temperature for 24h at 500rpm to obtain a reaction solution, centrifuge the reaction solution at 11000rpm for 12min to obtain a precipitate, wash the precipitate three times with deionized water and ethanol respectively, and air dry at room temperature for 24h to obtain ZnO@PDA intermediate, wherein the dopamine monomer is dopamine hydrochloride; S3. The ZnO@PDA intermediate obtained in step S2 was added to a copper salt aqueous solution with a concentration of 0.1 mol / L at a ratio of 2.6 g: 100 mL. The mixture was stirred at room temperature for 12 h at 500 rpm to obtain a reaction solution. The reaction solution was centrifuged at 11000 rpm for 12 min to obtain a precipitate. The precipitate was washed three times with deionized water and ethanol, respectively, and then dried naturally at room temperature for 24 h to obtain the ZnO@PDA@Cu composite material.

[0024] Raman spectroscopy was performed on ZnO and the ZnO@PDA intermediate obtained in step S2, respectively. The test results are as follows: Figure 1 (Raman spectrum of zinc oxide) and Figure 2 (Raman spectrum of ZnO@PDA intermediate) is shown. Figure 1 and Figure 2 Comparative analysis shows that, Figure 2 The presence of characteristic functional groups in the polydopamine interface layer formed by the oxidative self-polymerization of dopamine proves that the polydopamine interface layer was successfully constructed on the surface of zinc-containing inorganic particles.

[0025] The surface of the ZnO@PDA@Cu composite material prepared in step S3 was tested and analyzed by X-ray photoelectron spectroscopy (XPS). The test results are as follows: Figure 3 As shown. By Figure 3 The presence and distribution characteristics of copper on the material surface show that copper species were successfully fixed to the material surface through the polydopamine interface layer.

[0026] Zeta potentials were measured for ZnO, the ZnO@PDA intermediate obtained in step S2, and the ZnO@PDA@Cu composite material obtained in step S3, respectively. The test results are as follows: Figure 4 As shown. By Figure 4 It can be seen that the dispersion stability of ZnO@PDA intermediate and ZnO@PDA@Cu composite material is significantly better than that of zinc oxide. Example

[0027] The ZnO@PDA@Cu composite material was prepared according to the following steps: S1. Add zinc-containing inorganic particles to Tris-HCl buffer solution with a pH of 8.5 at a ratio of 0.5g:100mL, stir at room temperature at 500rpm for 40min, and then add an alkaline adjuster to adjust the pH of the system to 7.5 to obtain a zinc-containing inorganic particle suspension. The zinc-containing inorganic particles are zinc oxide particles with an average particle size of 100μm, and the alkaline adjuster is sodium carbonate. S2. Add dopamine monomer to the zinc-containing inorganic particle suspension obtained in step S1 at a ratio of 0.2g:100mL, stir at room temperature for 26h at 500rpm to obtain a reaction solution, centrifuge the reaction solution at 10000rpm for 15min to obtain a precipitate, wash the precipitate three times with deionized water and ethanol respectively, and air dry at room temperature for 24h to obtain ZnO@PDA intermediate, wherein the dopamine monomer is dopamine hydrochloride; S3. The ZnO@PDA intermediate obtained in step S2 was added to a copper salt aqueous solution with a concentration of 0.05 mol / L at a ratio of 2 g: 100 mL. The mixture was stirred at 500 rpm at room temperature for 14 h to obtain a reaction solution. The reaction solution was centrifuged at 10000 rpm for 15 min to obtain a precipitate. The precipitate was washed three times with deionized water and ethanol, respectively, and then naturally dried at room temperature for 24 h to obtain the ZnO@PDA@Cu composite material. Example

[0028] The ZnO@PDA@Cu composite material was prepared according to the following steps: S1. Add zinc-containing inorganic particles to Tris-HCl buffer solution with pH 8.4 at a ratio of 1g:100mL, stir at room temperature at 500rpm for 30min, and then add an alkaline adjuster to adjust the pH of the system to 7.2 to obtain a zinc-containing inorganic particle suspension. The zinc-containing inorganic particles are zinc oxide particles with an average particle size of 100μm, and the alkaline adjuster is potassium carbonate. S2. Add dopamine monomer to the zinc-containing inorganic particle suspension obtained in step S1 at a ratio of 0.5g:100mL, stir at room temperature for 24h at 500rpm to obtain a reaction solution, centrifuge the reaction solution at 11000rpm for 12min to obtain a precipitate, wash the precipitate three times with deionized water and ethanol respectively, and air dry at room temperature for 24h to obtain ZnO@PDA intermediate, wherein the dopamine monomer is dopamine hydrochloride; S3. The ZnO@PDA intermediate obtained in step S2 was added to a copper salt aqueous solution with a concentration of 0.1 mol / L at a ratio of 2.6 g: 100 mL. The mixture was stirred at room temperature for 12 h at 500 rpm to obtain a reaction solution. The reaction solution was centrifuged at 11000 rpm for 12 min to obtain a precipitate. The precipitate was washed three times with deionized water and ethanol, respectively, and then dried naturally at room temperature for 24 h to obtain the ZnO@PDA@Cu composite material. Example

[0029] The ZnO@PDA@Cu composite material was prepared according to the following steps: S1. Add zinc-containing inorganic particles to Tris-HCl buffer solution with a pH of 8.2 at a ratio of 1.5g:100mL, stir at room temperature at 600rpm for 25min, and then add an alkaline adjuster to adjust the pH of the system to 7.1 to obtain a zinc-containing inorganic particle suspension. The zinc-containing inorganic particles are zinc oxide particles with an average particle size of 100μm, and the alkaline adjuster is ammonia water with a mass fraction of 25%. S2. Add dopamine monomer to the zinc-containing inorganic particle suspension obtained in step S1 at a ratio of 0.8g:100mL, stir at room temperature for 25h at 600rpm to obtain a reaction solution, centrifuge the reaction solution at 11000rpm for 14min to obtain a precipitate, wash the precipitate three times with deionized water and ethanol respectively, and air dry at room temperature for 24h to obtain ZnO@PDA intermediate, wherein the dopamine monomer is dopamine hydrochloride; S3. The ZnO@PDA intermediate obtained in step S2 was added to a copper salt aqueous solution with a concentration of 0.08 mol / L at a ratio of 2.4 g: 100 mL. The mixture was stirred at 600 rpm at room temperature for 12 h to obtain a reaction solution. The reaction solution was centrifuged at 11000 rpm for 14 min to obtain a precipitate. The precipitate was washed three times with deionized water and ethanol, respectively, and then naturally dried at room temperature for 24 h to obtain the ZnO@PDA@Cu composite material.

[0030] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for preparing a ZnO@PDA@Cu composite material, characterized in that: Includes the following steps: S1. Add zinc-containing inorganic particles to buffer solution, stir at room temperature for 20-40 min, and then add alkaline adjuster to adjust the pH of the system to 7.0-7.5 to obtain zinc-containing inorganic particle suspension; S2. Add dopamine monomer to the zinc-containing inorganic particle suspension obtained in step S1, stir the reaction at room temperature for 22-26 hours to obtain a reaction solution, centrifuge the reaction solution to obtain a precipitate, wash the precipitate three times with deionized water and ethanol respectively, and dry it naturally at room temperature to obtain ZnO@PDA intermediate. S3. Add the ZnO@PDA intermediate obtained in step S2 to a copper salt aqueous solution and stir at room temperature for 10-14 hours to obtain a reaction solution. Centrifuge the reaction solution to obtain a precipitate. Wash the precipitate three times with deionized water and ethanol respectively, and then dry it naturally at room temperature to obtain the ZnO@PDA@Cu composite material. 2.The method for preparing ZnO@ PDA@ Cu composite material according to claim 1, characterized in that: In step S1, the zinc-containing inorganic particles are zinc oxide particles with an average particle size of 100 μm, the buffer solution is a Tris-HCl buffer solution with a pH of 8.0-8.5, and the ratio of zinc-containing inorganic particles to Tris-HCl buffer solution is (0.5-2) g: 100 mL.

3. The method according to claim 1, wherein the method comprises the following steps: 1) preparing ZnO nanoparticles; 2) preparing PDA; 3) preparing ZnO@PDA; 4) preparing Cu nanoparticles; 5) preparing ZnO@PDA@Cu. In step S1, the stirring speed at room temperature is 500-600 rpm.

4. The method according to claim 1, wherein the method is characterized by: In step S1, the alkalinity regulator is sodium carbonate, potassium carbonate, or ammonia water with a mass fraction of 25%.

5. The method according to claim 1, wherein the method is characterized by: In step S2, the dopamine monomer is dopamine hydrochloride, and the ratio of dopamine monomer to the zinc-containing inorganic particle suspension obtained in step S1 is (0.2-1) g: 100 mL.

6. The method for preparing a ZnO@PDA@Cu composite material according to claim 1, characterized in that: In step S2, the stirring speed at room temperature is 500-600 rpm, the centrifugation speed is 10000-12000 rpm, the centrifugation time is 10-15 min, and the natural drying time at room temperature is 24 h.

7. The method for preparing a ZnO@PDA@Cu composite material according to claim 1, characterized in that: In step S3, the concentration of the copper salt aqueous solution is 0.05-0.5 mol / L, and the copper salt is one of copper chloride, copper sulfate or copper nitrate. The ratio of the ZnO@PDA intermediate obtained in step S2 to the copper salt aqueous solution is (2-3) g: 100 mL.

8. The method for preparing a ZnO@PDA@Cu composite material according to claim 1, characterized in that: In step S3, the stirring speed at room temperature is 500-600 rpm, the centrifugation speed is 10000-12000 rpm, the centrifugation time is 10-15 min, and the natural drying time at room temperature is 24 h.

9. The ZnO@PDA@Cu composite material prepared by the preparation method according to claims 1 to 8.

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