Preparation method of flexible multifunctional film based on reliable interface combination and device

Abstract

The application discloses a preparation method and a device of a flexible multifunctional film based on reliable interface combination, and the preparation method comprises the following steps: first, a polymer containing an amino group is modified, a mercapto group is introduced into the molecular chain of the polymer, and the polymer is dissolved in deionized water; metal nanoparticles are added into a solution of the polymer containing the mercapto group, and after being uniformly dispersed, the solution is left to stand; the modified polymer containing the mercapto group and prepared conductive ink are layered and coated on a clean flexible substrate; after low-temperature drying and high-temperature sintering, a flexible multifunctional film with reliable bonding force is obtained, and the prepared flexible multifunctional film has multiple functions and can be used as an electromagnetic shielding film, a bending strain sensor and an electrothermal device.

Description

Technical Field

[0001] This invention belongs to the field of flexible electronic device fabrication technology, specifically relating to a method and device for fabricating flexible multifunctional thin films based on reliable interface bonding. Background Technology

[0002] Due to its unique ductility, flexibility, and low-cost manufacturing process, flexible electronics has broad application prospects in fields such as energy, medicine, artificial intelligence, and human-computer interaction. After decades of joint efforts from industry and academia, a large number of commercialized products have emerged in the field of flexible electronics, such as organic light-emitting diodes (OLEDs), flexible electronic displays, printed RFID tags, and thin-film solar cells. With its rapid development, the fields involved in flexible electronic devices are further expanding, and more practical products will inevitably emerge, bringing great convenience to people's production and lives. Research on flexible electronic devices has become a hot topic. The fabrication of flexible electronic devices typically requires the layer-by-layer deposition of functional materials onto a flexible substrate surface, thus involving extensive interface engineering in the fabrication process. As the boundary between different materials and phases, the interface bonding force, surface energy of the interface materials, and interface compatibility determine the performance and durability of flexible electronic devices. Therefore, researching methods to improve interface bonding performance and fabricating flexible electronic devices based on reliable interface bonding is of great significance to the development of the flexible electronics field.

[0003] Currently, most layered flexible electronic devices are fabricated using simple layer-by-layer deposition methods to directly prepare sandwich-structure flexible electronic devices, lacking effective bonding methods between the interfaces. Therefore, when the device deforms, due to the modulus mismatch between the layers, the functional layers are prone to fracture under stress, generating cracks or even out-of-plane deflection, leading to performance degradation or even failure of the device. Research has shown that enhancing interfacial bonding with silver-sulfur covalent bonds is an effective method to solve this problem. Chinese invention patent CN201811370513.6 proposes a method for preparing a chitosan transparent film based on a silver nanowire network. However, silver nanowires themselves have a large aspect ratio, making them prone to entanglement and difficult to disperse uniformly. Furthermore, this material generates high temperatures when current or voltage is applied, requiring certain temperature resistance of the substrate when used as an electrical device. Chinese invention patents CN201810126921.0 and CN201811370444.9 studied the antibacterial properties of thiol-chitosan-silver composite materials, but both only investigated the single function of the composite material. There are few reports in this field on bifunctional or multifunctional devices based on this material system. Therefore, fabricating multifunctional flexible electronic devices based on reliable interfacial bonding is a significant challenge in the current field of flexible electronic device fabrication. Summary of the Invention

[0004] This invention provides a method and device for fabricating flexible multifunctional thin films based on reliable interface bonding, ensuring reliable interface bonding between functional layers of a multilayer flexible electronic device, while also ensuring that the flexible electronic device has multiple practical functions.

[0005] To achieve the above objectives, the present invention provides a flexible multifunctional thin film based on reliable interface bonding and its preparation method, comprising the following steps:

[0006] S1. Modify the polymer particles to obtain a thiol-containing polymer. Take a portion of the thiol-containing polymer and dissolve it to obtain a thiol polymer solution. Add metal nanoparticles and a coupling agent to the thiol polymer solution. The mass of the metal nanoparticles is 10wt%-60wt% of the thiol polymer solution used, and the mass of the coupling agent is 2wt%-10wt% of the thiol polymer solution used. Disperse them evenly to obtain a metal nanoparticle-thiol polymer composite ink.

[0007] S2. A thiol polymer solution is coated onto a flexible substrate and dried to form a thiol polymer adhesive layer. Then, a metal nanoparticle-thiol polymer composite ink is coated onto the thiol polymer adhesive layer. The composite ink is completely dried and sintered at high temperature. The thiol polymer adhesive layer forms hydrogen bonds and chemical bonds with the flexible substrate and the metal nanoparticles, respectively, to obtain a flexible multifunctional film with reliable interfacial bonding ability.

[0008] Furthermore, in S1, the polymer particles are polymers containing amino groups in their molecular chains; the processing method is to prepare a polymer containing thiol groups by using N-acetyl-L-cysteine ​​as a modifier and 1-hydroxybenzotriazole and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride as condensing agents.

[0009] Furthermore, in S1, the metal nanoparticles are nanoparticles that can be covalently cross-linked with thiol groups.

[0010] Furthermore, in S1, the coupling agent is a silane coupling agent.

[0011] Furthermore, the flexible substrate in S2 is a polymer film that can withstand 300°C.

[0012] Furthermore, in S2, the temperature range for low-temperature drying of the ink is 45℃-80℃, and the drying time is 20min-60min.

[0013] Furthermore, in S2, the temperature range for high-temperature sintering of the thin film is 150℃-300℃, and the sintering time is 5min-30min.

[0014] An electromagnetic shielding device based on a reliable interface bonded flexible thin film includes a flexible multifunctional thin film prepared by the method described above.

[0015] A strain sensor based on a reliable interface combined with a flexible thin film includes a flexible multifunctional thin film prepared by the above method. The multifunctional thin film has two electrodes connected to its two ends. The two electrodes lead out resistance signals and are connected to a signal processing circuit. The signal processing circuit is used to acquire the resistance of the flexible multifunctional thin film and calculate the strain value based on the acquired resistance.

[0016] An electrothermal device based on a reliable interface bonded flexible thin film includes a flexible multifunctional thin film prepared by the above method, wherein electrodes are connected to both ends of the multifunctional thin film and the electrodes are used to connect to a power source.

[0017] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0018] (1) The method described in this invention introduces thiol groups into the molecular chain by modifying the amino-containing polymer material. Since thiol groups readily form coordination bonds with metal nanoparticles, chemical bonds can be formed between the metal nanoparticles in the metal nanoparticle-thiol polymer composite layer and the thiol polymer in the thiol polymer adhesive layer, resulting in reliable interfacial bonding between the two layers. Furthermore, due to the excellent adhesion of the thiol polymer itself, reliable interfacial bonding is achieved between the thiol polymer and the high-temperature resistant flexible substrate through hydrogen bonds. Therefore, reliable interfacial bonding is achieved between each layer of the flexible multifunctional thin film, thus completing the preparation of a flexible multifunctional thin film with reliable interfacial bonding capability. After multiple deformations, the resistance of this thin film remains almost unchanged compared to before bending, resulting in good long-term stability for sensors using this thin film, with no initial resistance drift.

[0019] (2) The prepared multilayer flexible film has the ability to shield electromagnetic waves and can be used as an electromagnetic shielding film. Its resistance can change with its bending degree, so it can be used as a bending strain sensor. Because its composite ink layer has ultra-high conductivity, it can heat up quickly in a short time, so it can be used as an electric heater heating device. Compared with the common single-function flexible electronic products on the market, this film has obvious advantages.

[0020] (3) This invention prepares a flexible multifunctional film based on reliable interface bonding through a simple coating process. The process is simple and conducive to large-scale production. The good bonding force between the layers of the film gives the film outstanding durability and practicality, and has excellent commercial value.

[0021] Furthermore, in the multilayer flexible film prepared by this invention, both the metal nanoparticle-thiol polymer composite layer and the thiol polymer adhesive layer are prepared on a high-temperature resistant flexible substrate and undergo high-temperature sintering treatment. Therefore, the multilayer flexible film has good temperature resistance and can work normally at 200°C, which is significantly superior to common flexible films such as polyurethane, polyethylene terephthalate and polydimethylsiloxane commonly found on the market. Attached Figure Description

[0022] Figure 1 : A flowchart of the preparation process of a flexible multifunctional thin film based on reliable interface bonding;

[0023] Figure 2 Schematic diagram of a multilayer thin film with reliable bonding capability;

[0024] Figure 3 : Schematic diagram of the working principle of the electromagnetic shielding film prepared in Example 1;

[0025] Figure 4 : Schematic diagram of the bending strain sensor prepared in Example 2;

[0026] Figure 5 : A schematic diagram of the structure of the electrothermal device prepared in Example 3;

[0027] Figure 6 Results of cyclic bending test of multilayer thin films with reliable bonding ability.

[0028] In the attached diagram: 1. Flexible multifunctional thin film; 2. Silver electrode; 3. Signal processing circuit; 4. DC power supply. Detailed Implementation

[0029] To make the objectives and technical solutions of this invention clearer and easier to understand, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0030] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more. In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0031] A method for preparing a flexible multifunctional thin film with reliable bonding capability is disclosed. The flexible multifunctional thin film includes a high-temperature resistant flexible thin film as a substrate, a metal nanoparticle-thiol-containing polymer composite conductive layer as a functional layer, and a thiol-containing polymer adhesive layer providing reliable bonding capability. First, an amino-containing polymer is modified by introducing thiol groups into its molecular chain and dissolved in deionized water. Metal nanoparticles are added to the solution of the thiol-containing polymer, uniformly dispersed, and allowed to stand. The modified thiol-containing polymer and the prepared conductive ink are layered and coated onto a clean flexible substrate. After low-temperature drying and high-temperature sintering, a flexible multifunctional thin film with reliable bonding is obtained. The prepared flexible multifunctional thin film has multiple functions and can be used as an electromagnetic shielding film, a bending strain sensor, and an electrothermal device.

[0032] The polymer used for modification is chitosan, and the metal nanoparticles are silver nanoparticles or gold nanoparticles.

[0033] Reference Figure 1 A method for preparing flexible multifunctional thin films based on reliable interface bonding includes the following steps:

[0034] S1. Weigh a certain amount of polymer particles and modify them. After modification, the polymer molecular chain contains thiol groups. Take a portion of the modified polymer and dissolve it in deionized water to obtain a saturated thiol polymer solution. Add a certain amount of metal nanoparticles and a certain amount of coupling agent to the thiol polymer solution, and disperse them evenly by water bath ultrasound and mechanical stirring to obtain metal nanoparticle-thiol polymer composite ink (referred to as composite ink). Then, let the prepared composite ink stand for a period of time to eliminate air bubbles.

[0035] S2. First, a thiol polymer solution is coated onto a clean flexible substrate and dried to form a thiol polymer adhesive layer. Then, a composite ink is coated onto the thiol polymer adhesive layer. The composite ink is completely dried at a low temperature for a certain time and then sintered at a high temperature for a certain time. The thiol-containing polymer forms hydrogen bonds and chemical bonds with the flexible substrate and metal nanoparticles, respectively, resulting in a flexible multifunctional film with reliable interfacial bonding ability.

[0036] Furthermore, in S1, the polymer particles are polymers containing amino groups in their molecular chains, such as chitosan. The treatment method involves using N-acetyl-L-cysteine ​​as a modifier, with an amount 4-6 times the mass of the amino-containing polymer, and using 1-hydroxybenzotriazole and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride as condensing agents, both of which are used at 60%-80% of the mass of the amino-containing polymer, to prepare a polymer containing thiol groups.

[0037] In S1, the metal nanoparticles are silver nanoparticles or gold nanoparticles, and the amount of metal nanoparticles used is 10wt%-60wt% of the mercapto polymer solution used.

[0038] In S1, the coupling agent is a silane coupling agent, and the amount of the coupling agent is 2wt%-10wt% of the mercapto polymer solution used.

[0039] In S2, the flexible substrate is a polymer film that can be used at 300°C for a short time, such as polyimide;

[0040] In S2, the layer coating method is drop coating, blade coating, spin coating, etc.

[0041] In S2, the temperature range for low-temperature drying of the ink is 45wt%-80℃, and the drying time is 20min-60min;

[0042] In S2, the temperature range of the high-temperature sintering film is 150wt%-300℃, and the sintering time is 5min-30min.

[0043] Reference Figure 2A flexible multifunctional thin film based on reliable interface bonding includes a metal nanoparticle-thiol polymer composite layer, a thiol polymer adhesive layer, and a high-temperature resistant flexible substrate arranged sequentially from top to bottom. The metal nanoparticle-thiol polymer composite layer and the thiol polymer adhesive layer are connected by chemical bonds, and the thiol polymer adhesive layer and the high-temperature resistant flexible substrate are connected by high-strength hydrogen bonds, which has reliable interface bonding and provides good durability for flexible multifunctional thin films with electromagnetic shielding, strain sensing and electrothermal functions.

[0044] Example 1

[0045] A method for preparing a flexible, multifunctional thin film with reliable bonding capability for electromagnetic shielding includes the following steps:

[0046] S1. Weigh a certain amount of polymer particles and modify them. After modification, the polymer molecular chain contains thiol groups. Take a portion of the modified polymer and dissolve it in deionized water to obtain a saturated thiol polymer solution. Add a certain amount of metal nanoparticles and a certain amount of coupling agent to the thiol polymer solution, and disperse them evenly by water bath ultrasound and mechanical stirring to obtain metal nanoparticle-thiol polymer composite ink (referred to as composite ink). Then, let the prepared composite ink stand for a period of time to eliminate air bubbles.

[0047] S2. First, a thiol polymer solution is coated onto a clean flexible substrate and dried at a low temperature. Then, a composite ink is coated onto the coating formed after the thiol polymer solution has dried. The composite ink is then treated at a low temperature for a certain time to completely dry, and then sintered at a high temperature for a certain time. The thiol-containing polymer forms hydrogen bonds and chemical bonds with the flexible substrate and metal nanoparticles, respectively, resulting in a flexible multifunctional film with reliable interfacial bonding ability.

[0048] Furthermore, in S1, the polymer particles are polymers containing amino groups in their molecular chains, such as chitosan. The treatment method involves using N-acetyl-L-cysteine ​​as a modifier, with an amount four times the mass of the amino-containing polymer, and using 1-hydroxybenzotriazole and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride as condensing agents, both of which are used at 60% of the mass of the amino-containing polymer, to prepare a polymer containing thiol groups.

[0049] In S1, the metal nanoparticles are silver nanoparticles, and the amount of silver nanoparticles used is 10 wt% of the mercapto polymer solution used.

[0050] In S1, the coupling agent is a silane coupling agent, and the amount of coupling agent used is 2 wt% of the mercapto polymer solution used.

[0051] In S2, the flexible substrate is a polymer film that can be used at 300°C for a short time, such as polyimide;

[0052] In S2, the layer coating method is drop coating;

[0053] In S2, the temperature range for low-temperature drying of the ink is 45°C, and the drying time is 60 min.

[0054] In S2, the temperature range for high-temperature sintering of the thin film is 150°C, and the sintering time is 30 min.

[0055] like Figure 3 As shown, the flexible multifunctional film prepared based on the above steps exhibits nanoscale particle size due to the high-temperature sintering of the composite ink layer. The large surface energy of these nanoparticles allows for spontaneous diffusion of surface atoms at temperatures far below their melting points. Limited mass transport between the nanoparticles causes necking, leading to extensive grain fusion and resulting in ultra-high electrical conductivity of the composite ink layer, reaching 5000 S / m to 60000 S / m. The significant impedance difference between the incident electromagnetic wave and the composite ink layer causes most of the electromagnetic wave to be reflected at the surface of the composite ink layer. Therefore, the film itself possesses electromagnetic shielding capabilities and can be used as an electromagnetic shielding device.

[0056] Example 2

[0057] A method for preparing a flexible, multifunctional thin film with reliable bonding for bending strain detection includes the following steps:

[0058] S1. Weigh a certain amount of polymer particles and modify them. After modification, the polymer molecular chain contains thiol groups. Take a portion of the modified polymer and dissolve it in deionized water to obtain a saturated thiol polymer solution. Add a certain amount of metal nanoparticles and a certain amount of coupling agent to the thiol polymer solution, and disperse them evenly by water bath ultrasound and mechanical stirring to obtain metal nanoparticle-thiol polymer composite ink (referred to as composite ink). Then, let the prepared composite ink stand for a period of time to eliminate air bubbles.

[0059] S2. First, a thiol polymer solution is coated onto a clean flexible substrate and dried at a low temperature. Then, a composite ink is coated onto the coating formed after the thiol polymer solution has dried. The composite ink is then treated at a low temperature for a certain time to completely dry, and then sintered at a high temperature for a certain time. The thiol-containing polymer forms hydrogen bonds and chemical bonds with the flexible substrate and metal nanoparticles, respectively, resulting in a flexible multifunctional film with reliable interfacial bonding ability.

[0060] Furthermore, in S1, the polymer particles are polymers containing amino groups in their molecular chains, such as chitosan. The treatment method involves using N-acetyl-L-cysteine ​​as a modifier, with an amount 5 times the mass of the amino-containing polymer, and using 1-hydroxybenzotriazole and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride as condensing agents, both of which are used at 70% of the mass of the amino-containing polymer, to prepare a polymer containing thiol groups.

[0061] In S1, the metal nanoparticles are silver nanoparticles, and the amount of silver nanoparticles used is 40 wt% of the mercapto polymer solution used.

[0062] In S1, the coupling agent is a silane coupling agent, and the amount of the coupling agent is 6 wt% of the mercapto polymer solution used.

[0063] In S2, the flexible substrate is a polymer film that can be used at 300°C for a short time, such as polyimide;

[0064] In S2, the layer coating method is spin coating;

[0065] In S2, the temperature range for low-temperature drying of the ink is 65°C, and the drying time is 40 minutes.

[0066] In S2, the temperature range for high-temperature sintering of the thin film is 200°C, and the sintering time is 10 min.

[0067] like Figure 4 As shown, the flexible multifunctional film 1 prepared based on the above steps has an increased resistance due to the increased spacing between silver nanoparticles in the composite ink layer caused by bending. Silver electrodes 2 are attached to both ends of the flexible multifunctional film 1 using conductive silver paste. The resistance signal is then extracted through the silver electrodes 2 and connected to a signal processing circuit 3 to obtain a strain sensor. The signal processing circuit 3 is used to acquire the resistance of the flexible multifunctional film and calculate the strain value based on the acquired resistance.

[0068] Example 3

[0069] A method for preparing a flexible multifunctional thin film with reliable bonding capability for use in electrothermal devices includes the following steps:

[0070] S1. Weigh a certain amount of polymer particles and modify them. After modification, the polymer molecular chain contains thiol groups. Take a portion of the modified polymer and dissolve it in deionized water to obtain a saturated thiol polymer solution. Add a certain amount of metal nanoparticles and a certain amount of coupling agent to the thiol polymer solution, and disperse them evenly by water bath ultrasound and mechanical stirring to obtain metal nanoparticle-thiol polymer composite ink (referred to as composite ink). Then, let the prepared composite ink stand for a period of time to eliminate air bubbles.

[0071] S2. First, a thiol polymer solution is coated onto a clean flexible substrate and dried at a low temperature. Then, a composite ink is coated onto the coating formed after the thiol polymer solution has dried. The composite ink is then treated at a low temperature for a certain time to completely dry, and then sintered at a high temperature for a certain time. The thiol-containing polymer forms hydrogen bonds and chemical bonds with the flexible substrate and metal nanoparticles, respectively, resulting in a flexible multifunctional film with reliable interfacial bonding ability.

[0072] In step S1, the polymer particles are polymers containing amino groups in their molecular chains, such as chitosan. The treatment method involves using N-acetyl-L-cysteine ​​as a modifier, with an amount 6 times the mass of the amino-containing polymer, and using 1-hydroxybenzotriazole and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride as condensing agents, both of which are used at 80% of the mass of the amino-containing polymer, to prepare a polymer containing thiol groups. In step S1, the metal nanoparticles are gold nanoparticles, and the amount of gold nanoparticles is 60 wt% of the thiol polymer solution used.

[0073] In S1, the coupling agent is a silane coupling agent, and the amount of the coupling agent is 10 wt% of the mercapto polymer solution used.

[0074] In S2, the flexible substrate is a polymer film that can be used at 300°C for a short time, such as polyimide;

[0075] In S2, the layer coating method is scraping.

[0076] In S2, the temperature range for low-temperature drying of the ink is 80°C, and the drying time is 20 minutes.

[0077] In S2, the temperature range for high-temperature sintering of the thin film is 300°C, and the sintering time is 5 minutes.

[0078] like Figure 5As shown, based on the above steps, the flexible multifunctional thin film is prepared by attaching silver electrodes 2 to both ends of the thin film 1 using conductive silver paste. Wires are then connected to a DC power supply 4 via the silver electrodes 2 to obtain an electrothermal device. Because the composite ink layer has extremely high conductivity and low resistance, under a 2-5V driving voltage, the flexible multifunctional thin film 1 can rapidly heat up in a short time due to the Joule heating effect, thus enabling its use as an electrothermal device.

[0079] Example 4

[0080] A method for preparing a flexible multifunctional thin film with reliable interfacial bonding capability includes the following steps:

[0081] S1. Weigh a certain amount of polymer particles and modify them. After modification, the polymer molecular chain contains thiol groups. Take a portion of the modified polymer and dissolve it in deionized water to obtain a thiol polymer solution. Add a certain amount of metal nanoparticles and a certain amount of coupling agent to the thiol polymer solution, and disperse them evenly by water bath ultrasound and mechanical stirring to obtain metal nanoparticle-thiol polymer composite ink (referred to as composite ink). Then, let the prepared composite ink stand for a period of time to eliminate air bubbles.

[0082] S2. First, a thiol polymer solution is coated onto a clean flexible substrate and dried at a low temperature. Then, a composite ink is coated onto the coating formed after the thiol polymer solution has dried. The composite ink is then treated at a low temperature for a certain time to completely dry, and then sintered at a high temperature for a certain time. The thiol-containing polymer forms hydrogen bonds and chemical bonds with the flexible substrate and metal nanoparticles, respectively, resulting in a flexible multifunctional film with reliable interfacial bonding ability.

[0083] Furthermore, in S1, the polymer particles are polymers containing amino groups in their molecular chains, such as chitosan. The treatment method involves using N-acetyl-L-cysteine ​​as a modifier, with an amount five times the mass of the amino-containing polymer, and using 1-hydroxybenzotriazole and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride as condensing agents, both of which are used at 75% of the mass of the amino-containing polymer, to prepare a polymer containing thiol groups. In S1, the metal nanoparticles are gold nanoparticles, and the amount of gold nanoparticles is 30 wt% of the thiol polymer solution used.

[0084] In S1, the coupling agent is a silane coupling agent, and the amount of the coupling agent is 5 wt% of the mercapto polymer solution used.

[0085] In S2, the flexible substrate is a polymer film that can be used at 300°C for a short time, such as polyimide;

[0086] In S2, the layer coating method is scraping.

[0087] In S2, the temperature range for low-temperature drying of the ink is 80°C, and the drying time is 30 minutes.

[0088] In S2, the temperature range for high-temperature sintering of the thin film is 250°C, and the sintering time is 5 minutes.

[0089] like Figure 6 As shown, the flexible multifunctional film prepared based on the above steps showed no significant change in resistance after 2000 bending cycles. This indicates that the metal nanoparticle-thiol polymer composite layer was not damaged during the cycling process due to the action of the thiol polymer binder layer, proving that the layers of this flexible multifunctional film have reliable interfacial bonding capabilities, thus demonstrating the film's outstanding durability and practicality.

[0090] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for preparing a flexible multifunctional film based on reliable interface bonding, characterized in that, The method comprises the following steps: S1, modifying the polymer particles to obtain a polymer containing a thiol group, taking part of the polymer containing a thiol group, dissolving it to obtain a thiol polymer solution; adding metal nanoparticles and a coupling agent to the thiol polymer solution, the mass of the metal nanoparticles being 10 wt%-60 wt% of the thiol polymer solution used, and the mass of the coupling agent being 2 wt%-10 wt% of the thiol polymer solution used, so that it is uniformly dispersed, to obtain a metal nanoparticle-thiol polymer composite ink; S2, coating the thiol polymer solution on a flexible substrate and drying to form a thiol polymer adhesive layer, then coating the metal nanoparticle-thiol polymer composite ink on the thiol polymer adhesive layer, completely drying the composite ink, and high-temperature sintering, the thiol polymer adhesive layer forming hydrogen bonds and chemical bonds with the flexible substrate and the metal nanoparticles respectively, to obtain a flexible multifunctional film with reliable interface bonding capacity; In the S1, the polymer particles are polymers containing amino groups in the molecular chain; the treatment method is to use N-acetyl-L-cysteine as a modifier, and 1-hydroxybenzotriazole and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride as condensating agents to prepare a polymer containing a thiol group; In the S1, the metal nanoparticles are nanoparticles that can be covalently crosslinked with thiol groups; In the S2, the flexible substrate in the S2 is a polymer film resistant to 300℃, the temperature range for high-temperature sintering of the film is 150℃-300℃, and the sintering time is 5 min-30 min.

2. The method of claim 1, wherein the method comprises: In the S1, the coupling agent is a silane coupling agent.

3. The method of claim 1, wherein the method further comprises: In the S2, the temperature range for low-temperature drying of the ink is 45℃-80℃, and the drying time is 20 min-60 min.

4. An electromagnetic shielding device based on a reliable interface bonding a flexible film, characterized in that, The flexible multifunctional film prepared by the method of claim 1.

5. A strain sensor based on a reliable interface bonded to a flexible film, characterized in that, The flexible multifunctional film prepared by the method of claim 1, two electrodes are connected to both ends of the multifunctional film, the two electrodes lead out a resistance signal and are connected to a signal processing circuit, and the signal processing circuit is used to collect the resistance of the flexible multifunctional film and calculate a strain value according to the collected resistance.

6. An electrocaloric device based on a reliable interface bonding a flexible film, characterized in that, The flexible multifunctional film prepared by the method of claim 1, an electrode is connected to both ends of the multifunctional film, and the electrode is used to be connected to a power supply.

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