A method for preparing Ag-NW conductive film based on water-water transfer activator interface

Abstract

The present invention provides a method for preparing a Ag-NW conductive film based on a water-water transfer activator interface. First, the Marangoni convection effect is used to promote the enrichment of Ag-NWs in the water transfer activator phase. Then, driven by anisotropic capillary forces, the Ag-NWs in the water transfer activator phase spontaneously form a conductive film with an ordered array structure. The entire interface assembly process can be completed in just 2 seconds, significantly improving the preparation efficiency. In addition, the Ag-NW conductive film prepared by the present invention has high conductivity, high mechanical flexibility, and excellent transfer flexibility. It can be easily transferred to any substrate surface through a liquid phase transfer method, which helps to promote the large-scale industrial production of Ag-NW conductive films.

Description

Technical Field

[0001] The invention relates to the field of Ag-NW conductive films, in particular to a method for preparing an Ag-NW conductive film based on a water-water transfer activator interface. Background Art

[0002] Conductive films constructed with metal layers are widely used in flexible circuits, sensors, electromagnetic shielding and other fields due to their high conductivity. At present, common methods for preparing conductive films in industry, such as printing and Mayer rod coating, are widely used because of their low equipment cost and adaptability to large-scale production needs. However, with the continuous development of science and technology, the conductive films prepared by these two preparation methods have been difficult to meet the high requirements of existing functional devices for the quality and performance of conductive films due to their low precision and material utilization. In addition, although other methods for preparing conductive films, such as template method and photolithography, can produce conductive films with high resolution and excellent stability, their high cost, time-consuming preparation process and difficulty in mass production have greatly limited their widespread application.

[0003] Researchers have proposed numerous approaches to the assembly and preparation of Ag-NW conductive films, including external field control, precision printing, Langmuir–Blodgett (LB) technology, and surface modification. While these methods have achieved some progress in achieving ordered structures and improving fabrication efficiency, they still face limitations in practical applications. For example, while external field control and precision printing offer some flexibility, their limited operational scope makes them difficult to meet the demands of large-scale Ag-NW film fabrication. While LB technology can achieve highly ordered nanowire arrangements, it requires specialized equipment, is complex to operate, and presents significant transfer challenges, significantly increasing costs and time. While surface modification can improve interactions between nanomaterials, thereby simplifying fabrication and improving fabrication efficiency, its lengthy and costly process limits its widespread adoption in practical applications. These aforementioned traditional methods for preparing Ag-NW conductive films are often accompanied by complex operations, low efficiency, and difficulty in fabricating transfers.

[0004] In recent years, interface assembly technology has become a research hotspot in the field of conductive film preparation due to its advantages such as simple operation, low cost and high preparation efficiency, and has received widespread attention and research. Through interface assembly technology, the uniform distribution of nanoparticles, nanosheets, carbon nanotubes and nanorods can be achieved, thereby preparing high-performance conductive films. For example, Shi et al. successfully prepared highly conductive Ag-NW conductive films through the oil-water-air three-phase interface assembly technology. This technology only requires dropping an Ag-NWs aqueous dispersion onto the chloroform surface to spontaneously form a water-oil-air three-phase interface, inducing the efficient assembly of Ag-NWs on the interface, and ultimately preparing Ag-NW conductive films with excellent performance. This method greatly simplifies the complex process of traditional preparation of Ag-NW conductive films and improves preparation efficiency. However, despite the significant advantages of this method, its assembly process still has certain limitations. Because the assembly process of Ag-NW conductive films first occurs at the edge of the contact area between the water phase and the substrate, and then gradually expands to the entire water-air interface, the assembly and preparation of Ag-NW conductive films are limited by a specific space, making it difficult to meet the needs of large-scale production in industry. Therefore, finding a strategy for efficiently preparing Ag-NW conductive films is of great significance to promoting the industrial production of Ag-NW conductive films.

[0005] Existing water transfer printing technology is commonly used for pattern transfer. The main components of water transfer activators are organic solvents, surfactants, and film-forming resins. In the common industrial pattern water transfer printing process, the water transfer activator's mechanism of action is divided into three steps: first, the water transfer activator dissolves the PVA film on the surface of the pattern layer, causing the pattern layer to detach and float on the water surface; second, the surfactant rich in the water transfer activator can modify the surface of the substrate, allowing the pattern layer to adhere to the substrate surface; finally, the film-forming resin rich in the water transfer activator acts as an adhesive to firmly bond the pattern layer to the substrate surface, completing the transfer.

[0006] There are currently no reports on the preparation of Ag-NW conductive films using water-water transfer activator interfaces. Summary of the Invention

[0007] The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide a method for preparing an Ag-NW conductive film based on a water-water transfer activator interface.

[0008] The technical solution adopted by the present invention is as follows: A method for preparing an Ag-NW conductive film based on a water-water transfer activator interface comprises the following steps:

[0009] S1, dispersing Ag-NWs into solvent A, adding water transfer activator solution and mixing evenly to obtain a mixed solution;

[0010] S2. Dropping the mixed solution obtained in step S1 onto a water surface to form an Ag-NW conductive film.

[0011] During the Ag-NW film formation process, the density difference between the water transfer activator and water, as well as the insolubility of the water transfer activator, creates a surface tension gradient at the liquid surface, triggering the Marangoni convection effect. Driven by this Marangoni convection, the Ag-NWs are rapidly enriched within the water transfer activator phase. Subsequently, the volatilization of volatile components (such as acetone) in the water transfer activator further accelerates the rapid dispersion and alignment of the Ag-NWs within the water transfer activator phase, thereby improving film formation efficiency. Compared to conventional surfactants, water transfer activators have a combination of wetting, dissolving, volatilizing, and bonding functions, rather than simply reducing surface tension.

[0012] Preferably, in step S1, the mass volume ratio of Ag-NWs to the water transfer activator solution is 10:(0.4-2) g / L.

[0013] Preferably, in step S1, the volume ratio of solvent A to water transfer activator solution is (1-5):1.

[0014] Preferably, in step S1, the solvent A is ethanol.

[0015] Preferably, in step S1, the water transfer activator solution comprises the following components:

[0016] Acetone 60%-70%;

[0017] Ethyl acetate 10%-15%;

[0018] Isopropyl alcohol 10%-15%;

[0019] Ethylene glycol butyl ether 3%-5%;

[0020] TX-10 1%-2%;

[0021] PVB resin 1%-2%.

[0022] Preferably, the method further comprises step S3:

[0023] S3. Transferring the Ag-NW conductive film obtained in step S2 to a substrate by a liquid phase transfer method and drying the Ag-NW conductive film to obtain a Ag-NW conductive film supported on the substrate.

[0024] Among them, the tool used for transfer can be a dropper, or it can be a separatory funnel, syringe or other instruments with liquid transfer and control functions; the substrate can be PET, PDMS, glass plate, coated paper, non-woven fabric, etc.

[0025] Preferably, in step S3, the substrate is PET or PDMS.

[0026] Preferably, the method further comprises step S4:

[0027] S4. Wash and dry the Ag-NW conductive film loaded on the substrate obtained in step S3.

[0028] Preferably, the washing in step S4 comprises the following steps:

[0029] S4-1, immersing the Ag-NW conductive film supported on the substrate in a sodium borohydride solution for 0.1-2 minutes and then taking it out. This step can further improve the conductivity of the Ag-NW conductive film;

[0030] S4-2. Remove excess sodium borohydride on the surface of the Ag-NW conductive film.

[0031] Preferably, an ethanol solution is used to remove excess sodium borohydride on the surface of the Ag-NW conductive film.

[0032] Preferably, the solvent of the sodium borohydride solution is a mixture of water and ethanol in a volume ratio of 1:1, and the concentration of the sodium borohydride solution is 0.01-0.5 mol / L.

[0033] Preferably, in steps S3 and S4, the drying temperature is 60-80° C. and the drying time is 5-15 min. The drying equipment is not limited to oven heating, and can also be other heating equipment such as a heating plate.

[0034] The beneficial effects of the present invention are as follows:

[0035] 1. This invention addresses the problems of complex operation, low efficiency, and difficulty in transferring Ag-NW conductive films in the preparation of traditional interface assembly techniques. We innovatively propose a strategy for preparing Ag-NW conductive films based on water-water transfer activator interface assembly. This strategy first promotes the enrichment of Ag-NWs within the water transfer activator phase through the Marangoni convection effect. Then, driven by anisotropic capillary forces, the Ag-NWs within the water transfer activator phase spontaneously form a conductive film with an ordered array structure. Based on the above mechanism, the entire interface assembly process can be completed in just 2 seconds, significantly improving the preparation efficiency. Furthermore, the Ag-NW conductive films prepared based on this strategy exhibit high conductivity, high mechanical flexibility, and excellent transfer flexibility, and can be easily transferred to any substrate surface via liquid phase transfer.

[0036] 2. The Ag-NW conductive film preparation method of the present invention is simple, effective and rapid, and can be operated in an atmospheric environment.

[0037] 3. The preparation of Ag-NW conductive films by the present invention has the advantages of simple operation, high efficiency and easy transfer, which will help promote the large-scale industrial production of Ag-NW conductive films. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying any creative work, other drawings obtained based on these drawings still fall within the scope of the present invention.

[0039] Figure 1 Schematic diagram of the process for preparing the Ag-NW conductive film of the present invention;

[0040] Figure 2 (a) Optical photograph of the Ag-NW conductive film prepared in Example 1 of the present invention; (b, c) SEM images of the PET / AgNW conductive film at low and high magnifications;

[0041] Figure 3 This is a process diagram for preparing an Ag-NW conductive film according to Example 1 of the present invention;

[0042] Figure 4 Conductivity diagrams of (a) PET / AgNW conductive film and (b) PDMS / AgNW conductive film prepared in Example 1 of the present invention;

[0043] Figure 5 Figure 2 shows the changes in the sheet resistance of (a) the PET / AgNW conductive film and (b) the PDMS / AgNW conductive film prepared in Example 1 of the present invention under cyclic testing at a fixed bending diameter and twisting angle; (c, d) the changes in the sheet resistance of the PDMS / AgNW conductive film under different bending diameters and twisting angles.

[0044] Figure 6 Schematic diagram of the transfer process of the Ag-NW conductive film in Example 1 of the present invention;

[0045] Figure 7 The Ag-NW conductive film prepared in Example 1 of the present invention is (a) patterned on a PET substrate and (b) patterned on different substrates. DETAILED DESCRIPTION

[0046] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be described in further detail below with reference to the accompanying drawings.

[0047] Example 1

[0048] This embodiment provides a method for preparing an Ag-NW conductive film based on a water-water transfer activator interface, comprising the following steps:

[0049] Step S1: 10 mg of Ag-NWs were uniformly dispersed in 2 mL of ethanol, and 0.6 mL of water transfer activator solution was added thereto and mixed thoroughly.

[0050] Step S2: Use a dropper to drop the mixed solution obtained in step S1 dropwise onto a circular water surface with a diameter of 10 cm at a rate of 0.25 mL / min to form an Ag-NW conductive film with a diameter of 10 cm.

[0051] Step S3: The Ag-NW conductive film prepared in step S2 is sucked out by a dropper and transferred to a PET substrate, and dried at 70° C. to obtain a PET-based Ag-NW conductive film, i.e., a PET / AgNW conductive film.

[0052] Step S4: 200 μL of PDMS solution was evenly spin-coated on the surface of the PET / AgNW conductive film. After drying at 70 °C, the Ag-NWs on the PET surface were completely transferred to the PDMS film through mechanical peeling, resulting in a Ag-NWs conductive film with PDMS as the substrate, namely the PDMS / AgNW conductive film.

[0053] Step S5: The Ag-NWs conductive films on different substrates prepared in steps S3 and S4 were immersed in a sodium borohydride (NaBH4) solution with a concentration of 0.01-0.5 mol / L and a solvent ratio of 1:1 between water and ethanol for 30 s. The residual NaBH4 was then washed clean with ethanol and dried at 70 °C for 2 min to obtain PET / AgNW and PDMS / AgNW conductive films with clean surfaces.

[0054] Example 2

[0055] The preparation method provided in this embodiment differs from that in Example 1 only in that, in step S1 , the amount of water transfer activator solution added is 1 mL.

[0056] Example 3

[0057] The preparation method provided in this embodiment differs from that in Example 1 only in that, in step S1 , the amount of water transfer activator solution added is 2 mL.

[0058] Example 4

[0059] The preparation method provided in this embodiment differs from that in Example 1 only in that, in step S1 , the amount of water transfer activator solution added is 0.5 mL.

[0060] Example 5

[0061] The preparation method provided in this embodiment differs from that in Example 1 only in that, in step S1 , the amount of water transfer activator solution added is 0.4 mL.

[0062] The water transfer activator solution used in various embodiments of the present invention is composed of: 60%-70% acetone; 10%-15% ethyl acetate; 10%-15% isopropyl alcohol; 3%-5% ethylene glycol butyl ether; 1%-2% TX-10; and 1%-2% PVB resin. Testing has shown that the water transfer activator solution within these ratios achieves essentially the same results as in the embodiments of the present invention.

[0063] In Examples 1-5, the ratio of the water transfer activator solution to the Ag-NWs was adjusted, and the results obtained from the tests were basically the same. The Ag-NW conductive film prepared in Example 1 is now taken as an example to characterize and illustrate its effects.

[0064] like Figure 2 (a) shows an optical photograph of the Ag-NW conductive film assembled in Example 1, which shows that the Ag-NW conductive film prepared based on the water-water transfer activator interface assembly is uniform, smooth, and has a metallic luster. In order to explore the structural characteristics of the Ag-NW conductive film prepared based on the water-water transfer activator interface assembly, the morphology of PET / AgNW was characterized by SEM, as shown in Figure 2. Figure 2 (b, c) show the SEM images of PET / AgNW conductive film at low and high magnification. The results show that the Ag-NW conductive film prepared based on water-water transfer activator interface assembly presents a highly dense and regular arrangement, forming a parallel and ordered array structure.

[0065] In order to verify that the strategy of preparing Ag-NW conductive films based on water-water transfer activator interface assembly can significantly improve the preparation efficiency, we accurately recorded the complete process and time required from the moment a drop of mixed solution (water transfer activator, ethanol and Ag-NWs) was dropped onto the water surface to the moment Ag-NWs assembled into a film on the interface. Figure 3 The process of preparing Ag-NW conductive films based on water-water transfer activator interface assembly is shown. The results show that Ag-NWs can quickly assemble at the water-water transfer activator interface in just 2 seconds. Therefore, the preparation of Ag-NW conductive films based on water-water transfer activator interface assembly significantly improves the preparation efficiency of Ag-NW conductive films and lays a solid foundation for the efficient and large-scale production of Ag-NW conductive films.

[0066] In order to evaluate the conductive properties of Ag-NW conductive films prepared based on water-water transfer activator interface assembly, we tested the conductivity of PET / AgNW conductive films and PDMS / AgNW conductive films using a dual-electrical four-probe tester. The test results showed that the conductivity of PET / AgNW conductive films was significantly improved compared with that of PDMS / AgNW conductive films ((2.8±0.1)×10 5 S / m), the PET / AgNW conductive film has better conductivity ((3.2±0.1)×10 5 This result shows that the Ag-NW conductive film prepared by water-water transfer activator interface assembly has excellent conductive properties, which can meet the high conductivity requirements of functional devices and provide a solid foundation for the application of Ag-NW conductive films in various functional devices.

[0067] In order to explore the mechanical flexibility of Ag-NW conductive films prepared based on water-water transfer activator interface assembly, we conducted bending and twisting tests on PET / AgNW conductive films and PDMS / AgNW conductive films. Figure 5 As shown in (a, b), under the conditions of a bending diameter of 20 mm and a twisting angle of 180°, after 10,000 cycles of testing, the change in surface resistance (ΔR / R0) of the PET / AgNW and PDMS / AgNW conductive films did not exceed 0.14. Both PET / AgNW and PDMS / AgNW conductive films exhibited excellent mechanical flexibility. In addition, compared with the PET substrate, the PDMS substrate has higher softness and flexibility, especially after complete curing, the PDMS substrate can further enhance the adhesion with the Ag-NWs, thereby significantly improving the durability and stability of the conductive film. In view of these advantages of the PDMS substrate, we further evaluated the mechanical flexibility of the PDMS / AgNW conductive film. As Figure 5 As shown in (c, d), under the test conditions of different twist angles and bending diameters, the change in the sheet resistance of the PDMS / AgNW conductive film remains at an extremely low level, with the maximum increase being less than 0.01. These test results show that the strategy based on the interfacial assembly of water-water transfer activators gives the Ag-NW conductive film excellent mechanical flexibility, laying a solid foundation for its wide application in the field of flexible functional devices.

[0068] like Figure 6The figure shows the transfer process of a Ag-NW conductive film prepared by water-water transfer activator interface assembly. The Ag-NW conductive film, which has been prepared by water-water transfer activator interface assembly, is aspirated via liquid phase transfer and then dropped onto the PET surface. The Ag-NW conductive film can then be easily transferred to the PET substrate. This process, followed by multiple transfers and drying, allows for the preparation of intact, undamaged Ag-NW conductive films of any size, demonstrating the excellent transfer flexibility of the Ag-NW conductive film prepared by water-water transfer activator interface assembly.

[0069] The transfer flexibility of Ag-NW conductive films was further verified, and the patterning application of Ag-NW conductive films on different substrates can be realized based on the transfer flexibility of Ag-NW conductive films. Figure 7 As shown in (a), precise patterning of Ag-NW conductive films on PET substrates, prepared via interfacial assembly of water-water transfer activators, was achieved using a variety of pattern templates. The patterns prepared on the PET substrate not only exhibited high definition, but also exhibited uniform pattern distribution across the transferred Ag-NW conductive films, demonstrating flexible transfer and printing capabilities.

[0070] In order to verify the applicability of Ag-NW conductive films prepared based on water-water transfer activator interface assembly on different substrates, three representative substrate materials, namely rough coated paper, smooth glass and porous non-woven fabric, were selected in addition to the commonly used PET and PDMS. The Ag-NW conductive films were transferred to the above substrates using the liquid phase transfer method. Figure 7 As shown in (b), the Ag-NW conductive film prepared by the present invention can be successfully transferred to the above-mentioned various substrates, and the transferred pattern is clear and uniform, which is not affected by the properties of the substrate material, and high-quality patterning is achieved.

[0071] The above disclosure is merely a preferred embodiment of the present invention and certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for preparing Ag-NW conductive film based on water-water transfer activator interface, characterized in that: The steps include: S1, dispersing Ag-NWs into solvent A, adding water transfer activator solution and mixing evenly to obtain a mixed solution; S2, dropping the mixed solution obtained in step S1 onto a water surface to form an Ag-NW conductive film; In step S1, the composition of the water transfer activator solution is: Acetone 60%-70%; Ethyl acetate 10%-15%; Isopropyl alcohol 10%-15%; Ethylene glycol butyl ether 3%-5%; TX-10 1%-2%; PVB resin 1%-2%.

2. The method for preparing a Ag-NW conductive film based on a water-water transfer activator interface according to claim 1, characterized in that: In step S1 , the mass-to-volume ratio of Ag-NWs to the water transfer activator solution is 10:(0.4-2) g / L.

3. The method for preparing a Ag-NW conductive film based on a water-water transfer activator interface according to claim 1, characterized in that: In step S1, the volume ratio of solvent A to water transfer activator solution is (1-5):

1.

4. The method for preparing a Ag-NW conductive film based on a water-water transfer activator interface according to claim 1, characterized in that: In step S1, the solvent A is ethanol.

5. The method for preparing a Ag-NW conductive film based on a water-water transfer activator interface according to any one of claims 1 to 4, characterized in that: Also includes step S3: S3. Transferring the Ag-NW conductive film obtained in step S2 to a substrate by a liquid phase transfer method and drying the Ag-NW conductive film to obtain a Ag-NW conductive film supported on the substrate.

6. The method for preparing a Ag-NW conductive film based on a water-water transfer activator interface according to claim 5, characterized in that: In step S3, the substrate is PET or PDMS.

7. The method for preparing a Ag-NW conductive film based on a water-water transfer activator interface according to claim 5, characterized in that: Also includes step S4: S4. Wash and dry the Ag-NW conductive film loaded on the substrate obtained in step S3.

8. The method for preparing a Ag-NW conductive film based on a water-water transfer activator interface according to claim 7, characterized in that: The washing in step S4 comprises the following steps: S4-1, immersing the Ag-NW conductive film supported on the substrate in a sodium borohydride solution for 0.1-2 minutes and then taking it out; S4-2. Remove excess sodium borohydride on the surface of the Ag-NW conductive film.

9. The method for preparing a Ag-NW conductive film based on a water-water transfer activator interface according to claim 7, characterized in that: In steps S3 and S4, the drying temperature is 60-80° C., and the drying time is 5-15 min.

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