Preparation method and application of super-flexible stretchable conductive film substrate material

Abstract

The invention relates to the technical field of conductive film substrate materials, in particular to a preparation method and application of a super-flexible stretchable conductive film substrate material. In order to solve the problems that an existing flexible conductive film is prone to fracture in the stretching process, a conductive layer is prone to stripping, and the conductive performance is seriously attenuated along with deformation, the invention provides a composite polyrotaxane enhanced matrix film which is capable of meeting the ultra-flexible and stretchable requirements. And an MXene-silver nanowire-polypyrrole ternary synergistic conductive network is combined, so that the problem that the conductivity is sharply attenuated in the deformation process is solved.

Description

Technical Field

[0001] This invention relates to the field of conductive thin film substrate technology, and in particular to a method for preparing and applying an ultra-flexible stretchable conductive thin film substrate material. Background Technology

[0002] With the rapid development of flexible electronics, wearable devices, and foldable displays, more stringent requirements have been placed on conductive films, which are core components. While traditional indium tin oxide (ITO) films offer good light transmittance, their inherent brittleness makes them prone to breakage under bending or stretching deformation, failing to meet the demands of ultra-flexible and high-strain stretchable applications. Currently, transparent conductive films based on silver nanowires are considered the most promising alternative. However, existing silver nanowire films still have several problems. For example, most transparent conductive films using silver nanowires are adsorbed onto the substrate surface using simple physical adsorption methods, which easily lead to detachment and peeling during repeated bending, resulting in a decline in their electrical performance. Furthermore, most existing flexible substrates can only achieve a certain degree of bending, failing to achieve true flexible deformation and large stretching. Under tensile force, the nanowires or nanosheets in the conductive network can slip and separate, causing the conductive pathway to break, resulting in a sharp increase in resistance or even complete loss of conductivity. Therefore, there is an urgent need for an ultra-flexible stretchable conductive film substrate material that can withstand large mechanical deformation without damage, ensure a firm bond between the conductive layer and the substrate, and maintain stable conductivity during dynamic deformation. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of existing technologies by proposing a method for preparing and applying an ultra-flexible stretchable conductive thin film substrate material. Addressing the problems of easy breakage, easy peeling of the conductive layer, and severe attenuation of conductivity with deformation in existing flexible conductive films, this invention provides an ultra-flexible stretchable conductive thin film substrate material that utilizes composite polyrotaxane to enhance the mechanical properties of the substrate film, enabling it to meet the requirements of ultra-flexibility and stretchability. Furthermore, by combining an MXene-silver nanowire-polypyrrole ternary synergistic conductive network, it solves the problem of rapid attenuation of conductivity during deformation.

[0004] To achieve the above objectives, the present invention employs the following technical solution: a method for preparing an ultra-flexible stretchable conductive thin film substrate material, comprising the following steps: Step S1: Add the composite electrode spraying liquid to the spraying device, and spray the composite electrode spraying liquid onto the transparent film under the conditions of a pressure of 0.5MPa and a spraying distance of 8cm. Then dry it at 50℃ to obtain the sprayed film layer. Step S2: Weigh the following raw materials by weight: 0.4-0.5 parts of composite polyrotaxane, 0.8-1 parts of citric acid, 1.2-1.5 parts of polyvinyl alcohol, 0.02-0.03 parts of glutaraldehyde solution and 8-10 parts of deionized water. Mix the composite polyrotaxane, citric acid, polyvinyl alcohol, glutaraldehyde solution and deionized water, coat it on the sprayed film layer, and then vacuum dry it at a temperature of 60°C. Peel it off to obtain an ultra-flexible stretchable conductive thin film substrate material. The mass fraction of the glutaraldehyde solution is 20%.

[0005] The transparent film is any one of transparent polyimide film, polycarbonate film, and transparent thermoplastic polyurethane elastomer film.

[0006] An application of an ultra-flexible stretchable conductive thin film substrate material, which can be used in the fields of flexible electronic materials, wearable devices and light guide films.

[0007] The composite polyrotaxane is prepared by the following steps: Step A1: Mix polyethylene glycol and pyridine, stir at a stirring speed of 120-150 rpm and a temperature of 50-55℃, add itaconic anhydride and 1,8-diazabicyclo[5.4.0]undec-7-ene, react for 10-12 h, cool to room temperature, precipitate with diethyl ether, filter, dry, and obtain end-modified polyethylene glycol; Furthermore, in step A1, the ratio of polyethylene glycol, pyridine, itaconic anhydride, and 1,8-diazabicyclo[5.4.0]undec-7-ene is 10-12g:45-50mL:2.2-2.4g:0.8-0.9mL, and the polyethylene glycol is PEG-20000.

[0008] Step A2: Mix end-modified polyethylene glycol and deionized water, stir at 120-150 rpm at room temperature, add α-cyclodextrin solution, stir for 8-10 min, let stand for 24 h, then sonicate for 1 h, add sodium bisulfite solution, heat to 85-90℃, react for 4-5 h, centrifuge, filter, wash with deionized water / acetone, freeze dry to obtain sulfonated polyrotaxane; Furthermore, in step A2, the ratio of the amount of end-modified polyethylene glycol, deionized water, α-cyclodextrin solution, and sodium bisulfite solution is 6-6.5g: 25-30mL: 18-20mL: 3-4mL, the mass concentration of the α-cyclodextrin solution is 0.14g / mL, and the mass fraction of the sodium bisulfite solution is 35%.

[0009] Step A3: Mix sulfonated polyrotaxane, hydrochloric acid solution and deionized water, stir at a stirring speed of 120-150 rpm at room temperature for 15-20 min, then add aniline and ammonium persulfate, cool to 2-5℃, react for 4-5 h, centrifuge, filter, wash with deionized water, dry, and obtain composite polyrotaxane. Furthermore, in step A3, the ratio of sulfonated polyrotaxane, hydrochloric acid solution, deionized water, aniline, and ammonium persulfate is 3.2-3.5g: 8-10mL: 60-65mL: 0.35-0.4mL: 0.25-0.3g, and the mass fraction of the hydrochloric acid solution is 37%.

[0010] Furthermore, in the preparation process of the composite polyrotaxane, 1,8-diazabicyclo[5.4.0]undec-7-ene is used as a catalyst. Itaconic anhydride reacts with the terminal hydroxyl groups of polyethylene glycol to form ester groups and introduce double bonds, thus obtaining end-modified polyethylene glycol. This is then mixed with an α-cyclodextrin solution to form a quasi-polyrotaxane structure through a solution method. Sodium bisulfite solution is then added for sulfonation modification, sulfonating the double bonds of the polyethylene glycol segments to sulfonate groups, thus obtaining sulfonated polyrotaxane. Hydrochloric acid is then used as an acid dopant. Since the sulfonate groups in the sulfonated polyrotaxane can also serve as an acid doping structure, aniline is used as a monomer, ammonium persulfate is used as a catalyst, and sulfonated polyrotaxane is used as a template to prepare the composite polyrotaxane.

[0011] The composite electrode coating solution is prepared through the following steps: Step B1: Mix lithium fluoride and hydrochloric acid, stir at 120-150 rpm at room temperature for 25-30 min, then add titanium aluminum carbide, react for 24 h, centrifuge, filter, wash with deionized water until neutral, ultrasonically exfoliate in ethanol, filter, dry to obtain MXene powder; mix γ-mercaptopropyltriethoxysilane coupling agent, ethanol and deionized water, stir at 240-300 rpm at room temperature for 20-30 min, then add MXene powder, heat to 60℃, react for 2-3 h, centrifuge, filter to obtain modified MXene powder; Furthermore, in step B1: during the preparation of the MXene dispersion, the ratio of lithium fluoride, hydrochloric acid, and titanium aluminum carbide is 2-2.1g: 38-40mL: 2-2.1g, and the mass fraction of the hydrochloric acid solution is 37%. During the preparation of the modified MXene dispersion, the ratio of γ-mercaptopropyltriethoxysilane coupling agent, ethanol, deionized water, and MXene powder is 10-12mL: 20-25mL: 100-120mL: 1.8-2g. In step B2: Modified MXene powder and N,N-dimethylformamide are mixed. At a stirring rate of 240-300 rpm and room temperature, a mixture of silver nanowires and ethanol is added and stirred for 30-40 min. Then pyrrole is added and stirring is continued for 15-20 min. The mixture is cooled to 2-5℃, stirred, and ammonium persulfate is added. The reaction is carried out for 6-8 h. The mixture is centrifuged, filtered, and washed with deionized water / ethanol to obtain a conductive mixture. The conductive mixture, N,N-dimethylformamide, and ethanol are mixed and ultrasonically dispersed for 15-20 min to obtain a composite electrode spraying solution. Furthermore, in step B2: during the preparation of the conductive mixture, the ratio of modified MXene powder, N,N-dimethylformamide, silver nanowires, ethanol, pyrrole, and ammonium persulfate is 0.03-0.05g: 10-12mL: 0.01-0.015g: 8-10mL: 0.05-0.06mL: 0.12-0.13g; during the preparation of the composite electrode spraying solution, the ratio of conductive mixture, N,N-dimethylformamide, and ethanol is 0.15-0.18g: 10-12mL: 8-10mL.

[0012] Furthermore, in the reaction process of preparing the composite electrode spraying solution: using MAX phase titanium aluminum carbide as material, lithium fluoride and hydrochloric acid as etching solution, MXene powder is prepared by selective etching method, and modified by γ-mercaptopropyltriethoxysilane coupling agent to introduce thiol groups into MXene powder to obtain modified MXene powder. The modified MXene powder is compounded with silver nanowires, and a compound is formed through the coordination between the thiol groups introduced in the modified MXene powder and silver. Pyrrole is added and polymerized under the action of ammonium persulfate to form a conductive mixture of MXene powder-silver nanowire-polypyrrole ternary system. Then, it is dispersed in N,N-dimethylformamide and ethanol system to obtain composite electrode spraying solution.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: In view of the problems that existing flexible conductive films are prone to breakage during stretching, easy peeling of conductive layer, and severe attenuation of conductivity with deformation, the present invention provides an ultra-flexible stretchable conductive film substrate material that uses composite polyrotaxane to enhance the mechanical properties of the substrate film so that it can meet the requirements of ultra-flexibility and stretchability, and combines MXene-silver nanowire-polypyrrole ternary synergistic conductive network to solve the problem of rapid attenuation of conductivity during deformation.

[0014] This invention introduces a composite polyrotaxane structure into a conductive thin film substrate material. During the preparation process, citric acid and glutaraldehyde are used as crosslinking agents, allowing the polyrotaxane structure to act as a molecular-level sliding reinforcing phase. The introduced cyclodextrin molecules are threaded onto the polymer chain, like pulleys on a rope. When the material is stretched, these "pulleys" can slide freely along the polymer chain, effectively dispersing external stress throughout the molecular network. This avoids stress concentration in local areas, which can lead to molecular chain breakage. As a result, the substrate material no longer relies on the macromolecular chain entanglement of traditional elastomers, thus achieving extremely high elongation at break. It can withstand thousands of repeated stretching cycles without permanent fatigue damage or breakage. In the composite electrode spraying solution, two-dimensional sheet-like MXene, one-dimensional linear silver nanowires, and zero-dimensional particulate polypyrrole are combined to construct a multi-dimensional synergistic conductive network of MXene-silver nanowires-polypyrrole. When the film is stretched, even if some silver nanowire overlap points separate, the current can still be transmitted through the backup electrical path constructed by the MXene sheets and polypyrrole particles. This multi-dimensional and multi-level synergistic effect ensures that the resistivity change rate of the film can still be kept within a certain range under high tensile strain, and achieves high stability of conductivity in dynamic deformation. Meanwhile, this invention employs a method of first spraying a composite electrode liquid onto a transparent film to form a conductive network material layer, and then coating a film substrate material. The subsequently coated substrate material can penetrate into the porous structure and gaps of the dried conductive network. During the curing process, polyvinyl alcohol molecular chains and composite polyrotaxane form a dense three-dimensional cross-linked network inside and on the surface of the conductive network, physically anchoring the conductive material. This is equivalent to casting the conductive network inside the substrate material at the microscale, rather than simply bonding the two layers together. This greatly increases the contact area and bonding force between the conductive layer and the substrate, allowing it to withstand repeated bending without any visible delamination or peeling of the conductive layer, thus achieving the integration of the conductive layer and the stretched substrate. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the reaction process for preparing sulfonated polyrotaxane according to the present invention. Detailed Implementation

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with existing known technologies. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0017] Example 1: A method for preparing an ultra-flexible stretchable conductive thin film substrate material, comprising the following steps: Step S1: Add the composite electrode spraying liquid to the spraying device, and spray the composite electrode spraying liquid onto the transparent film under the conditions of a pressure of 0.5 MPa and a spraying distance of 8 cm, and then dry it at 50 °C to obtain the sprayed film layer. Step S2: Weigh the following raw materials by weight: 0.4 parts composite polyrotaxane, 0.8 parts citric acid, 1.2 parts polyvinyl alcohol, 0.02 parts glutaraldehyde solution and 8 parts deionized water. Mix the composite polyrotaxane, citric acid, polyvinyl alcohol, glutaraldehyde solution and deionized water, coat it on the sprayed film layer, and then vacuum dry it at a temperature of 60°C. Peel it off to obtain an ultra-flexible stretchable conductive thin film substrate material. The mass fraction of the glutaraldehyde solution is 20%.

[0018] The transparent film is a transparent polyimide film.

[0019] The polyvinyl alcohol is PVA-1788.

[0020] An application of an ultra-flexible stretchable conductive thin film substrate material, which can be used in the fields of flexible electronic materials, wearable devices and light guide films.

[0021] The composite polyrotaxane is prepared by the following steps: Step A1: Mix polyethylene glycol and pyridine, stir at 120 rpm and 50 °C, add itaconic anhydride and 1,8-diazabicyclo[5.4.0]undec-7-ene, react for 10 h, cool to room temperature, precipitate with diethyl ether, filter, dry, and obtain end-modified polyethylene glycol; Furthermore, in step A1, the ratio of polyethylene glycol, pyridine, itaconic anhydride, and 1,8-diazabicyclo[5.4.0]undec-7-ene is 10g:45mL:2.2g:0.8mL.

[0022] The polyethylene glycol is PEG-20000.

[0023] Step A2: Mix end-modified polyethylene glycol and deionized water, stir at 120 rpm at room temperature, add α-cyclodextrin solution, stir for 8 min, let stand for 24 h, then sonicate for 1 h, add sodium bisulfite solution, heat to 85 °C, react for 4 h, centrifuge, filter, wash with deionized water / acetone, freeze dry to obtain sulfonated polyrotaxane; Furthermore, in step A2, the ratio of the amount of end-modified polyethylene glycol, deionized water, α-cyclodextrin solution, and sodium bisulfite solution is 6g:25mL:18mL:3mL, the mass concentration of the α-cyclodextrin solution is 0.14g / mL, and the mass fraction of the sodium bisulfite solution is 35%.

[0024] Step A3: Mix sulfonated polyrotaxane, hydrochloric acid solution and deionized water, stir at 120 rpm at room temperature for 15 min, then add aniline and ammonium persulfate, cool to 2℃, react for 4 h, centrifuge, filter, wash with deionized water, and dry to obtain composite polyrotaxane. Furthermore, in step A3, the ratio of sulfonated polyrotaxane, hydrochloric acid solution, deionized water, aniline, and ammonium persulfate is 3.2g:8mL:60mL:0.35mL:0.25g, and the mass fraction of the hydrochloric acid solution is 37%.

[0025] The composite electrode coating solution is prepared through the following steps: Step B1: Lithium fluoride and hydrochloric acid were mixed and stirred for 25 min at room temperature with a stirring speed of 150 rpm. Then titanium aluminum carbide was added and reacted for 24 h. After centrifugation, filtration, washing with deionized water until neutral, ultrasonic exfoliation in ethanol, filtration, and drying were performed to obtain MXene powder. γ-mercaptopropyltriethoxysilane coupling agent, ethanol, and deionized water were mixed and stirred for 20 min at room temperature with a stirring speed of 300 rpm. Then MXene powder was added, the temperature was raised to 60℃, and the reaction was performed for 3 h. After centrifugation and filtration, modified MXene powder was obtained. Furthermore, in step B1: during the preparation of the MXene dispersion, the ratio of lithium fluoride, hydrochloric acid, and titanium aluminum carbide is 2g:40mL:2g, and the mass fraction of the hydrochloric acid solution is 37%. During the preparation of the modified MXene dispersion, the ratio of γ-mercaptopropyltriethoxysilane coupling agent, ethanol, deionized water, and MXene powder is 12mL:20mL:120mL:1.8g.

[0026] The titanium aluminum carbide is from Yumu New Materials Co., Ltd., and the particle size is 400 mesh.

[0027] In step B2: Modified MXene powder and N,N-dimethylformamide are mixed. At a stirring rate of 300 rpm and room temperature, a mixture of silver nanowires and ethanol is added and stirred for 30 min. Then pyrrole is added and stirring is continued for 15 min. The mixture is cooled to 2℃, stirred, and ammonium persulfate is added. The reaction is carried out for 8 h. The mixture is centrifuged, filtered, and washed with deionized water / ethanol to obtain a conductive mixture. The conductive mixture, N,N-dimethylformamide, and ethanol are mixed and ultrasonically dispersed for 20 min to obtain a composite electrode spraying solution. Furthermore, in step B2: during the preparation of the conductive mixture, the ratio of modified MXene powder, N,N-dimethylformamide, silver nanowires, ethanol, pyrrole, and ammonium persulfate is 0.05g:10mL:0.015g:8mL:0.05mL:0.12g; during the preparation of the composite electrode spraying solution, the ratio of the conductive mixture, N,N-dimethylformamide, and ethanol is 0.15g:12mL:8mL.

[0028] The silver nanowires are from Yumu New Materials Co., Ltd., and the model number is EDCV.

[0029] Example 2: A method for preparing an ultra-flexible stretchable conductive thin film substrate material, comprising the following steps: Step S1: Add the composite electrode spraying liquid to the spraying device, and spray the composite electrode spraying liquid onto the transparent film under the conditions of a pressure of 0.5 MPa and a spraying distance of 8 cm, and then dry it at 50 °C to obtain the sprayed film layer. Step S2: Weigh the following raw materials by weight: 0.5 parts composite polyrotaxane, 0.8 parts citric acid, 1.2 parts polyvinyl alcohol, 0.03 parts glutaraldehyde solution and 10 parts deionized water. Mix the composite polyrotaxane, citric acid, polyvinyl alcohol, glutaraldehyde solution and deionized water, coat it on the sprayed film layer, and then vacuum dry it at a temperature of 60°C. Peel it off to obtain an ultra-flexible stretchable conductive thin film substrate material. The mass fraction of the glutaraldehyde solution is 20%.

[0030] The transparent film is a polycarbonate film.

[0031] The polyvinyl alcohol is PVA-1788.

[0032] An application of an ultra-flexible stretchable conductive thin film substrate material, which can be used in the fields of flexible electronic materials, wearable devices and light guide films.

[0033] The composite polyrotaxane is prepared by the following steps: Step A1: Mix polyethylene glycol and pyridine, stir at 120 rpm and 55°C, add itaconic anhydride and 1,8-diazabicyclo[5.4.0]undec-7-ene, react for 12 h, cool to room temperature, precipitate with diethyl ether, filter, dry, and obtain end-modified polyethylene glycol; Furthermore, in step A1, the ratio of polyethylene glycol, pyridine, itaconic anhydride, and 1,8-diazabicyclo[5.4.0]undec-7-ene is 10g:45mL:2.4g:0.8mL.

[0034] The polyethylene glycol is PEG-20000.

[0035] Step A2: Mix end-modified polyethylene glycol and deionized water, stir at 120 rpm at room temperature, add α-cyclodextrin solution, stir for 10 min, let stand for 24 h, then sonicate for 1 h, add sodium bisulfite solution, heat to 85 °C, react for 5 h, centrifuge, filter, wash with deionized water / acetone, freeze dry to obtain sulfonated polyrotaxane; Furthermore, in step A2, the ratio of the amount of end-modified polyethylene glycol, deionized water, α-cyclodextrin solution, and sodium bisulfite solution is 6g:30mL:18mL:4mL, the mass concentration of the α-cyclodextrin solution is 0.14g / mL, and the mass fraction of the sodium bisulfite solution is 35%.

[0036] Step A3: Mix sulfonated polyrotaxane, hydrochloric acid solution and deionized water, stir at 120 rpm at room temperature for 20 min, then add aniline and ammonium persulfate, cool to 2℃, react for 5 h, centrifuge, filter, wash with deionized water, and dry to obtain composite polyrotaxane. Furthermore, in step A3, the ratio of sulfonated polyrotaxane, hydrochloric acid solution, deionized water, aniline, and ammonium persulfate is 3.5g:8mL:60mL:0.4mL:0.25g, and the mass fraction of the hydrochloric acid solution is 37%.

[0037] The composite electrode coating solution is prepared through the following steps: Step B1: Lithium fluoride and hydrochloric acid were mixed and stirred for 25 min at room temperature with a stirring speed of 120 rpm. Then titanium aluminum carbide was added and reacted for 24 h. After centrifugation, filtration, washing with deionized water until neutral, ultrasonic exfoliation in ethanol, filtration, and drying were performed to obtain MXene powder. γ-mercaptopropyltriethoxysilane coupling agent, ethanol, and deionized water were mixed and stirred for 20 min at room temperature with a stirring speed of 240 rpm. Then MXene powder was added, the temperature was raised to 60℃, and the reaction was performed for 2 h. After centrifugation and filtration, modified MXene powder was obtained. Furthermore, in step B1: the ratio of lithium fluoride, hydrochloric acid, and titanium aluminum carbide used in the preparation of the MXene dispersion is 2g:38mL:2g, and the mass fraction of the hydrochloric acid solution is 37%. In the preparation of the modified MXene dispersion: the ratio of γ-mercaptopropyltriethoxysilane coupling agent, ethanol, deionized water, and MXene powder used is 10mL:20mL:100mL:1.8g.

[0038] The titanium aluminum carbide is from Yumu New Materials Co., Ltd., and the particle size is 400 mesh.

[0039] In step B2: Modified MXene powder and N,N-dimethylformamide are mixed. At a stirring rate of 240 rpm and room temperature, a mixture of silver nanowires and ethanol is added and stirred for 30 min. Then pyrrole is added and stirring is continued for 15 min. The mixture is cooled to 2℃, stirred, and ammonium persulfate is added. The reaction is carried out for 6 h. The mixture is centrifuged, filtered, and washed with deionized water / ethanol to obtain a conductive mixture. The conductive mixture, N,N-dimethylformamide, and ethanol are mixed and ultrasonically dispersed for 15 min to obtain a composite electrode spraying solution. Furthermore, in step B2: during the preparation of the conductive mixture, the ratio of modified MXene powder, N,N-dimethylformamide, silver nanowires, ethanol, pyrrole, and ammonium persulfate is 0.03g:10mL:0.01g:8mL:0.05mL:0.12g; during the preparation of the composite electrode spraying solution, the ratio of the conductive mixture, N,N-dimethylformamide, and ethanol is 0.15g:10mL:8mL.

[0040] The silver nanowires are from Yumu New Materials Co., Ltd., and the model number is EDCV.

[0041] Example 3: A method for preparing an ultra-flexible stretchable conductive thin film substrate material, comprising the following steps: Step S1: Add the composite electrode spraying liquid to the spraying device, and spray the composite electrode spraying liquid onto the transparent film under the conditions of a pressure of 0.5 MPa and a spraying distance of 8 cm, and then dry it at 50 °C to obtain the sprayed film layer. Step S2: Weigh the following raw materials by weight: 0.5 parts composite polyrotaxane, 1 part citric acid, 1.5 parts polyvinyl alcohol, 0.03 parts glutaraldehyde solution and 10 parts deionized water. Mix the composite polyrotaxane, citric acid, polyvinyl alcohol, glutaraldehyde solution and deionized water, coat it onto the sprayed film layer, and then vacuum dry it at a temperature of 60°C. Peel it off to obtain an ultra-flexible stretchable conductive thin film substrate material. The mass fraction of the glutaraldehyde solution is 20%.

[0042] The transparent film is a transparent thermoplastic polyurethane elastomer film.

[0043] The polyvinyl alcohol is PVA-1788.

[0044] An application of an ultra-flexible stretchable conductive thin film substrate material, which can be used in the fields of flexible electronic materials, wearable devices and light guide films.

[0045] The composite polyrotaxane is prepared by the following steps: Step A1: Mix polyethylene glycol and pyridine, stir at 150 rpm and 55°C, add itaconic anhydride and 1,8-diazabicyclo[5.4.0]undec-7-ene, react for 12 h, cool to room temperature, precipitate with diethyl ether, filter, dry, and obtain end-modified polyethylene glycol; Furthermore, in step A1, the ratio of polyethylene glycol, pyridine, itaconic anhydride, and 1,8-diazabicyclo[5.4.0]undec-7-ene is 12g:50mL:2.4g:0.9mL.

[0046] The polyethylene glycol is PEG-20000.

[0047] Step A2: Mix end-modified polyethylene glycol and deionized water, stir at 150 rpm at room temperature, add α-cyclodextrin solution, stir for 10 min, let stand for 24 h, then sonicate for 1 h, add sodium bisulfite solution, heat to 90 °C, react for 5 h, centrifuge, filter, wash with deionized water / acetone, freeze dry to obtain sulfonated polyrotaxane; Furthermore, in step A2, the ratio of the amount of end-modified polyethylene glycol, deionized water, α-cyclodextrin solution and sodium bisulfite solution is 6.5g:30mL:20mL:4mL, the mass concentration of the α-cyclodextrin solution is 0.14g / mL, and the mass fraction of the sodium bisulfite solution is 35%.

[0048] Step A3: Mix sulfonated polyrotaxane, hydrochloric acid solution and deionized water, stir at 150 rpm at room temperature for 20 min, then add aniline and ammonium persulfate, cool to 5℃, react for 5 h, centrifuge, filter, wash with deionized water, and dry to obtain composite polyrotaxane. Furthermore, in step A3, the ratio of sulfonated polyrotaxane, hydrochloric acid solution, deionized water, aniline, and ammonium persulfate is 3.5g:10mL:65mL:0.4mL:0.3g, and the mass fraction of the hydrochloric acid solution is 37%.

[0049] The composite electrode coating solution is prepared through the following steps: Step B1: Lithium fluoride and hydrochloric acid were mixed and stirred for 30 min at room temperature with a stirring speed of 150 rpm. Then titanium aluminum carbide was added and the reaction was carried out for 24 h. After centrifugation, filtration, washing with deionized water until neutral, ultrasonic exfoliation in ethanol, filtration, and drying were performed to obtain MXene powder. γ-mercaptopropyltriethoxysilane coupling agent, ethanol, and deionized water were mixed and stirred for 30 min at room temperature with a stirring speed of 300 rpm. Then MXene powder was added, the temperature was raised to 60℃, and the reaction was carried out for 3 h. After centrifugation and filtration, modified MXene powder was obtained. Furthermore, in step B1: the ratio of lithium fluoride, hydrochloric acid, and titanium aluminum carbide used in the preparation of the MXene dispersion is 2.1g:40mL:2.1g, and the mass fraction of the hydrochloric acid solution is 37%. In the preparation of the modified MXene dispersion: the ratio of γ-mercaptopropyltriethoxysilane coupling agent, ethanol, deionized water, and MXene powder used is 12mL:25mL:120mL:2g.

[0050] The titanium aluminum carbide is from Yumu New Materials Co., Ltd., and the particle size is 400 mesh.

[0051] In step B2: Modified MXene powder and N,N-dimethylformamide are mixed. At a stirring rate of 300 rpm and room temperature, a mixture of silver nanowires and ethanol is added and stirred for 40 min. Then pyrrole is added and stirring is continued for 20 min. The mixture is cooled to 5℃, stirred, and ammonium persulfate is added. The reaction is carried out for 8 h. The mixture is centrifuged, filtered, and washed with deionized water / ethanol to obtain a conductive mixture. The conductive mixture, N,N-dimethylformamide, and ethanol are mixed and ultrasonically dispersed for 20 min to obtain a composite electrode spraying solution. Furthermore, in step B2: during the preparation of the conductive mixture, the ratio of modified MXene powder, N,N-dimethylformamide, silver nanowires, ethanol, pyrrole, and ammonium persulfate is 0.05g:12mL:0.015g:10mL:0.06mL:0.13g; during the preparation of the composite electrode spraying solution, the ratio of the conductive mixture, N,N-dimethylformamide, and ethanol is 0.18g:12mL:10mL.

[0052] The silver nanowires are from Yumu New Materials Co., Ltd., and the model number is EDCV.

[0053] Comparative Example 1: Compared with Example 3, the modified MXene powder in the preparation process of the composite electrode spraying liquid in Example 3 was removed, while the other steps were the same.

[0054] Comparative Example 2: Compared with Example 3, the composite polyrotaxane in the preparation process of the ultra-flexible stretchable conductive thin film substrate material in Example 3 was removed, while the other steps were the same.

[0055] The ultra-flexible stretchable conductive film substrates prepared in Examples 1, 2, 3, Comparative Example 1, and Comparative Example 2 were used. The transmittance of the conductive film substrates was measured using a UV-Vis spectrophotometer at a wavelength of 550 nm, with a transparent glass slide as the measurement baseline. The sheet resistance of the conductive film substrates was tested using a micro-ohmmeter via a four-probe method. The substrates were bent in the same manner at a bending angle of 180° for 500 bends. The sheet resistance after bending was recorded, and the rate of change of sheet resistance was calculated as: (Sheet resistance after bending - Initial sheet resistance) / Initial sheet resistance * 100%. The conductive film substrates were fixed on a tensile testing machine, with both ends of the film connected to the micro-ohmmeter via copper foil. The sheet resistance during the stretching process was recorded, and the rate of change of tensile sheet resistance was calculated as: (Maximum tensile sheet resistance - Initial sheet resistance) / Initial sheet resistance * 100%. The stretching rate was 5 mm / min, and the tensile strain was 150%. The test results are shown in the table below. Table 1 Test Results As shown in the table, the test results indicate that when comparing Examples 1, 2, and 3 with Comparative Examples 1 and 2, Comparative Example 1, compared to Example 3, removed the modified MXene powder in the preparation process of the composite electrode spraying liquid in Example 3. This reduced the amount of filler added, which improved the light transmittance, but significantly reduced its electrical performance. Comparative Example 2, compared to Example 3, removed the composite polyrotaxane in the preparation process of the ultra-flexible stretchable conductive film substrate material in Example 3. Without the composite polyrotaxane, the film substrate lacked a sliding pulley structure, leading to molecular chain breakage due to localized stress concentration during bending and stretching. This affected the bonding between the matrix material and the conductive material, resulting in a significant decrease in its electrical performance.

[0056] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing an ultra-flexible stretchable conductive thin film substrate material, characterized in that: The process includes the following steps: Step S1: Add the composite electrode spraying liquid to the spraying device, and spray the composite electrode spraying liquid onto the transparent film under the conditions of a pressure of 0.5MPa and a spraying distance of 8cm, and then dry it at 50℃ to obtain the sprayed film layer. Step S2: Weigh the following raw materials by weight: 0.4-0.5 parts of composite polyrotaxane, 0.8-1 parts of citric acid, 1.2-1.5 parts of polyvinyl alcohol, 0.02-0.03 parts of glutaraldehyde solution and 8-10 parts of deionized water. Mix the composite polyrotaxane, citric acid, polyvinyl alcohol, glutaraldehyde solution and deionized water, coat it on the sprayed film layer, and then vacuum dry it at a temperature of 60°C. Peel it off to obtain an ultra-flexible stretchable conductive thin film substrate material. The mass fraction of the glutaraldehyde solution is 20%.

2. The method for preparing an ultra-flexible stretchable conductive thin film substrate material according to claim 1, characterized in that: The transparent film is any one of transparent polyimide film, polycarbonate film, and transparent thermoplastic polyurethane elastomer film.

3. The method for preparing an ultra-flexible stretchable conductive thin film substrate material according to claim 1, characterized in that: The composite polyrotaxane is prepared by the following steps: Step A1: Mix polyethylene glycol and pyridine, stir at a stirring speed of 120-150 rpm and a temperature of 50-55℃, add itaconic anhydride and 1,8-diazabicyclo[5.4.0]undec-7-ene, react for 10-12 h, cool to room temperature, precipitate with diethyl ether, filter, dry, and obtain end-modified polyethylene glycol; Step A2: Mix end-modified polyethylene glycol and deionized water, stir at 120-150 rpm at room temperature, add α-cyclodextrin solution, stir for 8-10 min, let stand for 24 h, then sonicate for 1 h, add sodium bisulfite solution, heat to 85-90℃, react for 4-5 h, centrifuge, filter, wash with deionized water / acetone, freeze dry to obtain sulfonated polyrotaxane; Step A3: Mix sulfonated polyrotaxane, hydrochloric acid solution and deionized water, stir at a stirring speed of 120-150 rpm at room temperature for 15-20 min, then add aniline and ammonium persulfate, and cool to 2-5℃, react for 4-5 h, centrifuge, filter, wash with deionized water, and dry to obtain composite polyrotaxane.

4. The method for preparing an ultra-flexible stretchable conductive thin film substrate material according to claim 3, characterized in that: In step A1, the ratio of polyethylene glycol, pyridine, itaconic anhydride and 1,8-diazabicyclo[5.4.0]undec-7-ene is 10-12g: 45-50mL: 2.2-2.4g: 0.8-0.9mL.

5. The method for preparing an ultra-flexible stretchable conductive thin film substrate material according to claim 3, characterized in that: In step A2: the ratio of the amount of end-modified polyethylene glycol, deionized water, α-cyclodextrin solution and sodium bisulfite solution is 6-6.5g: 25-30mL: 18-20mL: 3-4mL, the mass concentration of the α-cyclodextrin solution is 0.14g / mL, and the mass fraction of the sodium bisulfite solution is 35%.

6. The method for preparing an ultra-flexible stretchable conductive thin film substrate material according to claim 3, characterized in that: In step A3: the ratio of sulfonated polyrotaxane, hydrochloric acid solution, deionized water, aniline and ammonium persulfate is 3.2-3.5g: 8-10mL: 60-65mL: 0.35-0.4mL: 0.25-0.3g, and the mass fraction of hydrochloric acid solution is 37%.

7. The method for preparing an ultra-flexible stretchable conductive thin film substrate material according to claim 1, characterized in that: The composite electrode coating solution is prepared through the following steps: Step B1: Mix lithium fluoride and hydrochloric acid, stir at 120-150 rpm at room temperature for 25-30 min, then add titanium aluminum carbide, react for 24 h, centrifuge, filter, wash with deionized water until neutral, ultrasonically exfoliate in ethanol, filter, dry to obtain MXene powder; mix γ-mercaptopropyltriethoxysilane coupling agent, ethanol and deionized water, stir at 240-300 rpm at room temperature for 20-30 min, then add MXene powder, heat to 60℃, react for 2-3 h, centrifuge, filter to obtain modified MXene powder; In step B2: Modified MXene powder and N,N-dimethylformamide are mixed. At a stirring rate of 240-300 rpm and room temperature, a mixture of silver nanowires and ethanol is added and stirred for 30-40 min. Then pyrrole is added and stirring is continued for 15-20 min. The mixture is cooled to 2-5℃, stirred, and ammonium persulfate is added. The reaction is carried out for 6-8 h. The mixture is centrifuged, filtered, and washed with deionized water / ethanol to obtain a conductive mixture. The conductive mixture, N,N-dimethylformamide, and ethanol are mixed and ultrasonically dispersed for 15-20 min to obtain a composite electrode spraying solution.

8. The method for preparing an ultra-flexible stretchable conductive thin film substrate material according to claim 7, characterized in that: In step B1: During the preparation of the MXene dispersion, the ratio of lithium fluoride, hydrochloric acid, and titanium aluminum carbide is 2-2.1g: 38-40mL: 2-2.1g, and the mass fraction of the hydrochloric acid solution is 37%. During the preparation of the modified MXene dispersion, the ratio of γ-mercaptopropyltriethoxysilane coupling agent, ethanol, deionized water, and MXene powder is 10-12mL: 20-25mL: 100-120mL: 1.8-2g.

9. The method for preparing an ultra-flexible stretchable conductive thin film substrate material according to claim 7, characterized in that: In step B2: During the preparation of the conductive mixture, the ratio of modified MXene powder, N,N-dimethylformamide, silver nanowires, ethanol, pyrrole, and ammonium persulfate is 0.03-0.05g: 10-12mL: 0.01-0.015g: 8-10mL: 0.05-0.06mL: 0.12-0.13g. During the preparation of the composite electrode spraying solution, the ratio of conductive mixture, N,N-dimethylformamide, and ethanol is 0.15-0.18g: 10-12mL: 8-10mL.

10. The application of the ultra-flexible stretchable conductive thin film substrate material obtained by the preparation method according to any one of claims 1-9, characterized in that: It can be applied to flexible electronic materials, wearable devices, and light guide films.

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