A method for preparing a covalently cross-linked PEDOT:PSS elastic electrode

Abstract

The application provides a preparation method of a covalently cross-linked PEDOT:PSS elastic electrode, comprising the following steps: S1, a water-soluble / water-dispersible cross-linking agent containing double-end active functional groups, a PEDOT:PSS water-dispersible solution and a conductive auxiliary agent are injected into a container for blending treatment to obtain a mixed solution; S2, the mixed solution is coated on a substrate for drying treatment and covalent cross-linking treatment to obtain the PEDOT:PSS elastic electrode. The application has the beneficial effect that the water-soluble / water-dispersible cross-linking agent is introduced to directly form covalent cross-linking with the molecular chain of PEDOT:PSS, and a stable network node is constructed; meanwhile, the conductive auxiliary agent is introduced to improve the stretchability, elasticity and conductivity of the PEDOT:PSS elastic electrode, so that the force-electric stability of the elastic electrode can be ensured.

Description

A method for preparing covalently crosslinked PEDOT:PSS elastic electrodes Technical Field

[0001] This invention relates to the fields of conductive polymer materials and flexible electronics, and more specifically, to a method for preparing a covalently cross-linked PEDOT:PSS elastic electrode. Background Technology

[0002] With the development of living standards and science and technology, flexible electronic products or elastic electronic products are attracting more and more attention. Electrodes are usually an essential part of various electronic devices. Therefore, improving the elasticity of electrode materials is of great significance to the development of flexible electronic products. How to obtain elastic electrodes with high electromechanical stability, easy solution processing, and low surface roughness has become a major challenge in the development of flexible electronic products.

[0003] Over the past 30 years, PEDOT:PSS (poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid) has been the most widely studied conductive polymer, mainly because it has good thermal stability, high electrical conductivity and solution processability. Its suspension has been successfully commercialized and widely used in organic photovoltaics, organic transistors and flexible electronics. However, the stretchability of dried PEDOT:PSS films is limited, and other substances need to be doped to achieve both high stretchability and high conductivity.

[0004] In the existing technology, the methods to improve the tensile strength and conductivity of PEDOT:PSS can be roughly divided into three types. The first method is to dope PEDOT:PSS with small molecule additives, such as ionic liquids, surfactants, and sorbitol. These small molecules can act as plasticizers and mix with polar solvents, thereby improving the tensile strength and conductivity of PEDOT:PSS. However, small molecules are prone to detachment and loss from the mixed film, resulting in unstable electromechanical properties of the film. The second method is to mix PEDOT:PSS with elastomers or soft polymers, which can significantly improve the tensile strength of PEDOT:PSS, but usually reduces the conductivity of the material. The third method is to construct a semi-interpenetrating network by mixing active monomers with the PEDOT:PSS solution and then curing it by light or heat treatment, thereby improving the mechanical stability of the film. However, the added insulating polymer will reduce the conductivity of PEDOT:PSS and exhibit creep and hysteresis characteristics, resulting in unstable electromechanical properties of PEDOT:PSS under strain conditions.

[0005] Therefore, it can be seen that all three methods mentioned above suffer from poor electromechanical stability of the elastic electrode. Summary of the Invention

[0006] The problem to be solved by the present invention is to provide a method for preparing a covalently cross-linked PEDOT:PSS elastic electrode that can ensure the electromechanical stability of the elastic electrode.

[0007] To address the above problems, this invention provides a method for preparing a covalently cross-linked PEDOT:PSS elastic electrode, comprising the following steps:

[0008] Step S1: A water-soluble / water-dispersible crosslinking agent containing dual-terminal active functional groups, a PEDOT:PSS water dispersion solution, and a conductive additive are injected into a container for blending to obtain a mixed solution;

[0009] Step S2: The mixed solution is coated onto a substrate and then dried and covalently crosslinked to obtain a PEDOT:PSS elastic electrode.

[0010] Preferably, in step S1, the dual-terminal active functional groups of the water-soluble / water-dispersible crosslinking agent are any one of epoxy functional groups, azide functional groups, and bisacrylidine functional groups.

[0011] Preferably, in step S1, the main chain structure of the water-soluble / water-dispersible crosslinking agent is any one of polyethylene glycol, polypropylene glycol, polyacrylamide, polyvinyl alcohol, polyacrylic acid, and polyvinylpyrrolidone, and the main chain molecular weight range of the main chain structure is 500 to 100,000 Da.

[0012] Preferably, in step S1, the conductive additive is any one of dimethyl sulfoxide, ethylene glycol, ionic liquid, and surfactant.

[0013] Preferably, in step S2, the coating treatment of the mixed solution is any one of solution drop casting, blade coating, spin coating, or mold coating.

[0014] Preferably, in step S2, the substrate is any one of glass sheet, silicon wafer, ceramic sheet, PET sheet, and elastomer film.

[0015] Preferably, in step S2, the thickness of the substrate is 50 nm to 2 mm.

[0016] Preferably, in step S2, the method for drying the blended membrane is either ventilation drying or vacuum drying.

[0017] Preferably, in step S2, the covalent crosslinking treatment of the blend membrane further includes:

[0018] The blended membrane is subjected to thin-film vacuum heat treatment or heating plate heat treatment at a temperature environment of 60℃~200℃.

[0019] Preferably, after performing step S2, the method further includes:

[0020] The PEDOT:PSS elastic electrode is treated with concentrated sulfuric acid or methanol.

[0021] The present invention has the following beneficial effects: By blending and thermally crosslinking the water-soluble / water-dispersible crosslinking agent, PEDOT:PSS water dispersion solution and conductive additive, the present invention can achieve direct covalent crosslinking of the molecular chains of the water-soluble / water-dispersible crosslinking agent on PEDOT:PSS and phase separation of PEDOT and PSS, thereby enhancing the electromechanical stability of the PEDOT:PSS elastic electrode. At the same time, by introducing conductive additive, good tensile strength, elasticity and conductivity can be ensured. Attached Figure Description

[0022] Figure 1 is a flowchart of the steps of the present invention;

[0023] Figure 2 is a schematic diagram of the preparation principle of the PEDOT:PSS elastic electrode of the present invention;

[0024] Figure 3 is a comparison of the Young's modulus, tensile strength, elongation at break and electrical conductivity of the PEDOT:PSS elastic electrodes prepared in Examples 1 to 5 of the present invention.

[0025] Figure 4 is a comparison of the Young's modulus, tensile strength, elongation at break and electrical conductivity of the PEDOT:PSS elastic electrodes prepared in Examples 1, 6 to 10 of the present invention.

[0026] Figure 5 shows the resistance change of the PEDOT:PSS elastic electrode prepared in Embodiment 1 and Embodiment 7 of the present invention as strain increases.

[0027] Figure 6 shows the resistance change of the PEDOT:PSS elastic electrode prepared in Examples 11 to 13 of the present invention as strain increases;

[0028] Figure 7 is a schematic diagram of the resistance change and cycle performance of the PEDOT:PSS elastic electrode prepared in Example 11 of the present invention as strain increases;

[0029] Figure 8 is a schematic diagram of the mechanical and electrical properties of the PEDOT:PSS elastic electrode prepared in Example 14 of the present invention when used to fabricate a capacitive sensor. Detailed Implementation

[0030] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0031] In a preferred embodiment of the present invention, based on the above-mentioned problems existing in the prior art, a method for preparing a covalently cross-linked PEDOT:PSS elastic electrode is provided, as shown in Figure 1, comprising the following steps:

[0032] Step S1: A water-soluble / water-dispersible crosslinking agent containing dual-terminal active functional groups, a PEDOT:PSS water dispersion solution, and a conductive additive are injected into a container for blending to obtain a mixed solution;

[0033] Step S2: The mixed solution is coated onto the substrate and then dried and covalently cross-linked to obtain the PEDOT:PSS elastic electrode.

[0034] Specifically, in this embodiment, considering that constructing suitable network nodes in linear polymer chains can transform plastic polymers into elastic networks and improve their electromechanical stability, this embodiment introduces soft segment crosslinking agents, namely water-soluble / water-dispersible crosslinking agents, to directly form covalent crosslinks with the molecular chains of PEDOT:PSS, thereby constructing stable network nodes. At the same time, conductive additives are introduced to improve the tensile strength, elasticity, and conductivity of the PEDOT:PSS elastic electrode.

[0035] Preferably, the conductivity and mechanical properties of PEDOT:PSS elastic electrodes prepared by adding crosslinking agents in different mass ratios are different. Therefore, in actual operation, different mass ratios of water-soluble / water-dispersible crosslinking agents and PEDOT:PSS water dispersion solutions can be selected according to the requirements to prepare PEDOT:PSS elastic electrodes with corresponding properties.

[0036] Preferably, the conductivity and mechanical properties of PEDOT:PSS elastic electrodes prepared by adding different types and mass ratios of conductive additives are different. Therefore, in actual operation, different types and mass ratios of conductive additives can be selected according to the needs to prepare PEDOT:PSS elastic electrodes with corresponding properties.

[0037] Specifically, in this embodiment, the preparation principle of the PEDOT:PSS elastic electrode is shown in Figure 2, where a represents the difference between plasticity and elasticity, b represents the interaction between one of the crosslinking agents, polyethylene glycol diglycidyl ether (PEGDE), and the PEDOT:PSS suspension, and c represents the crosslinking reaction between PEGDE and PSS. As can be seen from the figure, the added PEGDE crosslinking agent can form a crosslinking network with PSS, and at the same time, it can cause phase separation of PEDOT:PSS, thereby improving the material conductivity.

[0038] Preferably, the PEDOT:PSS suspensions used in the above embodiments were all purchased from Heraeus, with a solid content of 1.3 wt% and a PEDOT to PSS weight ratio of 1:2.5.

[0039] In a preferred embodiment of the present invention, in step S1, the dual-terminal active functional groups of the water-soluble / water-dispersible crosslinking agent are any one of epoxy functional groups, azide functional groups, and bisacrylidine functional groups.

[0040] In a preferred embodiment of the present invention, in step S1, the main chain structure of the water-soluble / water-dispersible crosslinking agent is any one of polyethylene glycol, polypropylene glycol, polyacrylamide, polyvinyl alcohol, polyacrylic acid, and polyvinylpyrrolidone, and the main chain molecular weight range of the main chain structure is 500 to 100,000 Da.

[0041] In a preferred embodiment of the present invention, in step S1, the conductive additive is any one of dimethyl sulfoxide, ethylene glycol, ionic liquid, and surfactant.

[0042] Specifically, in this embodiment, the weight of the conductive additive is 0-20% of the sum of the weight of the conductive additive and the weight of the PEDOT:PSS aqueous dispersion solution, that is, the doping amount of the conductive additive is 0-20 wt% of the total amount of the conductive additive and the PEDOT:PSS aqueous dispersion solution.

[0043] Preferably, conductive additives can improve the electrical properties of the PEDOT:PSS elastic electrode by phase separation of PEDOT and PSS and doping.

[0044] In a preferred embodiment of the present invention, in step S2, the coating treatment of the mixed solution of water-soluble / water-dispersible crosslinking agent, PEDOT:PSS water dispersion solution and conductive additive is performed by any one of solution drop casting, blade coating, spin coating and mold coating.

[0045] In a preferred embodiment of the present invention, in step S2, the substrate is any one of glass sheet, silicon wafer, ceramic sheet, PET sheet, and elastomer film.

[0046] In a preferred embodiment of the present invention, in step S2, the thickness of the substrate is 50 nm to 2 mm.

[0047] In a preferred embodiment of the present invention, in step S2, the method of drying the blended film is either ventilation drying or vacuum drying.

[0048] Specifically, in this embodiment, the ambient temperature during vacuum drying of the blended membrane is 30°C to 80°C.

[0049] In a preferred embodiment of the present invention, step S2, when performing covalent crosslinking treatment on the blend film, further includes:

[0050] The blended membrane is subjected to thin-film vacuum heat treatment or heating plate heat treatment at a temperature environment of 60℃~200℃.

[0051] In a preferred embodiment of the present invention, after performing step S2, the method further includes:

[0052] The PEDOT:PSS elastic electrode is treated with concentrated sulfuric acid or methanol.

[0053] Specifically, in this embodiment, the conductivity of the PEDOT:PSS elastic electrode can be further improved after either concentrated sulfuric acid treatment or methanol treatment, so that the conductivity of the PEDOT:PSS elastic electrode can be in the range of 100 to 10000 S / cm.

[0054] Preferably, different post-processing methods can control the conductivity and mechanical properties of PEDOT:PSS elastic electrodes. Therefore, in actual operation, the corresponding post-processing method can be selected according to the requirements to prepare PEDOT:PSS elastic electrodes with corresponding properties.

[0055] Preferably, after testing, the final PEDOT:PSS elastic electrode has an electrode film thickness ranging from 10 nm to 500 μm, a conductivity ranging from 0.01 to 10000 S / cm, an elongation at break ranging from 10% to 200%, a resistance change rate controlled within 10% to 500% under 50% strain, and a mechanical recovery rate ranging from 20% to 90%.

[0056] Preferably, the PEDOT:PSS elastic electrode prepared by this method can be used to prepare a capacitive strain sensor.

[0057] Example 1:

[0058] 0.0130 g of PEGDE6K (Mn: 6000 Da) was mixed with 1 g of PEDOT:PSS suspension and stirred in a Vortex for 1 h. The mixture was then cast onto a 2.5 cm * 7.5 cm glass slide and dried under ventilation. Subsequently, it was dried in a vacuum drying oven at 60 °C for 8 h and then at 120 °C for 90 min to prepare a PEDOT:PSS elastic electrode with a crosslinking agent content of 50 wt%. The Young's modulus, tensile strength, elongation at break, and conductivity of the PEDOT:PSS elastic electrode are shown in Figure 3. The resistance change under strain conditions is shown in Figure 5.

[0059] Example 2:

[0060] 0.0087 g of PEGDE6K was mixed with 1 g of PEDOT:PSS suspension and stirred with Vortex for 1 h. The mixture was then cast onto a 2.5 cm * 7.5 cm glass slide for ventilation and drying. Subsequently, it was dried in a vacuum drying oven at 60 °C for 8 h and then at 120 °C for 90 min to prepare a PEDOT:PSS elastic electrode with a crosslinking agent content of 40 wt%. The Young's modulus, tensile strength, elongation at break and conductivity of the PEDOT:PSS elastic electrode are shown in Figure 3.

[0061] Example 3:

[0062] 0.0056 g of PEGDE6 was mixed with 1 g of PEDOT:PSS suspension and stirred with Vortex for 1 h. The mixture was then cast onto a 2.5 cm * 7.5 cm glass slide for ventilation and drying. Subsequently, it was dried in a vacuum drying oven at 60 °C for 8 h and then at 120 °C for 90 min to prepare a PEDOT:PSS elastic electrode with a crosslinking agent content of 20 wt%. The Young's modulus, tensile strength, elongation at break and conductivity of the PEDOT:PSS elastic electrode are shown in Figure 3.

[0063] Example 4:

[0064] 0.0195 g of PEGDE6K was mixed with 1 g of PEDOT:PSS suspension and stirred with Vortex for 1 h. The mixture was then cast onto a 2.5 cm * 7.5 cm glass slide for ventilation and drying. Subsequently, it was dried in a vacuum drying oven at 60 °C for 8 h and then at 120 °C for 90 min to prepare a PEDOT:PSS elastic electrode with a crosslinking agent content of 60 wt%. The Young's modulus, tensile strength, elongation at break and conductivity of the PEDOT:PSS elastic electrode are shown in Figure 3.

[0065] Example 5:

[0066] 0.0303 g of PEGDE6K was mixed with 1 g of PEDOT:PSS suspension and stirred with Vortex for 1 h. The mixture was then cast onto a 2.5 cm * 7.5 cm glass slide for aeration and drying. Subsequently, it was dried in a vacuum drying oven at 60 °C for 8 h and then at 120 °C for 90 min to prepare a PEDOT:PSS elastic electrode with a crosslinking agent content of 70 wt%. The Young's modulus, tensile strength, elongation at break and conductivity of the PEDOT:PSS elastic electrode are shown in Figure 3.

[0067] As shown in Figure 3, Figure 3 illustrates the mechanical and electrical properties of PEDOT:PSS elastic electrode films with different crosslinking agent contents prepared through Examples 1 to 5. Figure a represents the Young's modulus and tensile strength of the PEDOT:PSS elastic electrodes prepared in Examples 1 to 5, and Figure b represents the elongation at break and conductivity of the PEDOT:PSS elastic electrodes prepared in Examples 1 to 5. It can be seen from the figures that the addition of the soft-segment crosslinking agent PEGDE can significantly reduce the Young's modulus and tensile strength of the PEDOT:PSS elastic electrode, while simultaneously enhancing the elongation at break and conductivity of the PEDOT:PSS elastic electrode. This indicates that the soft-segment crosslinking agent PEGDE plays a phase separation role in the PEDOT:PSS elastic electrode, releasing PEDOT from the core-shell structure and improving conductivity.

[0068] Example 6:

[0069] 0.0130 g of PEGDE6K was mixed with 1 g of PEDOT:PSS suspension and stirred with Vortex for 1 h. The mixture was then cast onto a 2.5 cm * 7.5 cm glass slide for aeration and drying. Subsequently, it was dried in a vacuum drying oven at 60 °C for 8 h to prepare a cross-linked PEDOT:PSS elastic electrode at 60 °C. The Young's modulus, tensile strength, elongation at break, and conductivity of the PEDOT:PSS elastic electrode are shown in Figure 4.

[0070] Example 7:

[0071] 0.0130 g of PEGDE6K was mixed with 1 g of PEDOT:PSS suspension and stirred with Vortex for 1 h. The mixture was then cast onto a 2.5 cm * 7.5 cm glass slide for aeration and drying. Subsequently, it was dried at 60 °C for 8 h in a vacuum drying oven and then at 110 °C for 90 min to prepare a cross-linked PEDOT:PSS elastic electrode at 110 °C. The Young's modulus, tensile strength, elongation at break, and conductivity of the PEDOT:PSS elastic electrode are shown in Figure 4. The resistance change under strain conditions is shown in Figure 5.

[0072] As shown in Figure 5, Figure 5 is a schematic diagram of the resistance change rate of the PEDOT:PSS elastic electrodes prepared by Example 1 and Example 7 under increased strain. Figure a is the PEDOT:PSS elastic electrode of Example 1, and Figure b is the PEDOT:PSS elastic electrode of Example 7. It can be seen from the figure that the resistance change of the prepared PEDOT:PSS elastic electrode is less than 2 times under strain greater than 50%, showing good stability.

[0073] Example 8:

[0074] 0.0130 g of PEGDE6K was mixed with 1 g of PEDOT:PSS suspension and stirred with Vortex for 1 h. The mixture was then cast onto a 2.5 cm * 7.5 cm glass slide for aeration and drying. Subsequently, it was dried in a vacuum drying oven at 60 °C for 8 h and then at 130 °C for 90 min to prepare a cross-linked PEDOT:PSS elastic electrode at 130 °C. The Young's modulus, tensile strength, elongation at break, and conductivity of the PEDOT:PSS elastic electrode are shown in Figure 4.

[0075] Example 9:

[0076] 0.0130 g of PEGDE6K was mixed with 1 g of PEDOT:PSS suspension and stirred with Vortex for 1 h. The mixture was then cast onto a 2.5 cm * 7.5 cm glass slide for aeration and drying. Subsequently, it was dried in a vacuum drying oven at 60 °C for 8 h and then at 150 °C for 90 min to prepare a cross-linked PEDOT:PSS elastic electrode at 150 °C. The Young's modulus, tensile strength, elongation at break, and conductivity of the PEDOT:PSS elastic electrode are shown in Figure 4.

[0077] Example 10:

[0078] 0.0130 g of PEGDE6K was mixed with 1 g of PEDOT:PSS suspension and stirred with Vortex for 1 h. The mixture was then cast onto a 2.5 cm * 7.5 cm glass slide for aeration and drying. Subsequently, it was dried in a vacuum drying oven at 60 °C for 8 h and then dried at 180 °C for 90 min to prepare a cross-linked PEDOT:PSS elastic electrode at 180 °C. The Young's modulus, tensile strength, elongation at break, and conductivity of the PEDOT:PSS elastic electrode are shown in Figure 4.

[0079] As shown in Figure 4, the PEDOT:PSS elastic electrode films crosslinked at different temperatures prepared according to Examples 1, 6 to 10 represent the mechanical and electrical properties of the films. Figure a shows the Young's modulus and tensile strength of the PEDOT:PSS elastic electrode films prepared according to Examples 1, 6 to 10, while Figure b shows the elongation at break and electrical conductivity of the PEDOT:PSS elastic electrodes prepared according to Examples 1, 6 to 10. As can be seen from the figures, the Young's modulus and tensile strength of the PEDOT:PSS elastic electrodes increase with increasing crosslinking temperature, and the elongation at break reaches its maximum at 120°C. The electrical conductivity does not change significantly with increasing crosslinking temperature. By controlling the crosslinking temperature, PEDOT:PSS elastic electrodes with different mechanical properties can be prepared.

[0080] Example 11:

[0081] 0.0130 g of PEGDE6K was mixed with 1 g of PEDOT:PSS suspension and stirred with Vortex for 1 h. The mixture was then spin-coated onto a fluoroelastomer substrate at 1000 rpm and heated at 120 °C for 30 min to prepare a PEDOT:PSS elastic electrode supported by an elastic substrate. The PEDOT:PSS elastic electrode film was 300 nm thick. The resistance change under strain is shown in Figure 5, and the cycling performance under different strain conditions is shown in Figure 7.

[0082] As shown in Figure 7, the PEDOT:PSS elastic electrode film crosslinked with a fluoroelastomer substrate prepared in Example 11 exhibits excellent electrical cycling performance. Figure a represents the resistance change of the PEDOT:PSS elastic electrode under different strains, Figure b represents the resistance change of the PEDOT:PSS elastic electrode under 50% strain for different number of cycles, and Figure c represents the resistance change of the PEDOT:PSS elastic electrode after 100 cycles at 50% strain. As can be seen from the figures, the resistance of the PEDOT:PSS elastic electrode changes with strain, with a change rate of less than 2.5 times, which is superior to similar PEDOT:PSS electrodes. After multiple cycles, the resistance change remains stable, demonstrating good electromechanical stability.

[0083] Example 12:

[0084] 0.0130 g of PEGDE6K was mixed with 1 g of PEDOT:PSS suspension and stirred in a Vortex for 1 h. The mixture was then spin-coated onto a fluoroelastomer substrate at 800 rpm and heated at 120 °C for 30 min to prepare a PEDOT:PSS elastic electrode supported by an elastic substrate. The PEDOT:PSS elastic electrode film was 600 nm thick, and its resistance change under strain is shown in Figure 6.

[0085] Example 13:

[0086] 0.0130 g of PEGDE6K was mixed with 1 g of PEDOT:PSS suspension and stirred with Vortex for 1 h. The mixture was then spin-coated onto a fluoroelastomer substrate at 2000 rpm and heated at 120 °C for 30 min to prepare a PEDOT:PSS elastic electrode supported by an elastic substrate. The PEDOT:PSS elastic electrode film was 150 nm thick, and its resistance change under strain is shown in Figure 6.

[0087] As shown in Figure 6, the cross-linked PEDOT:PSS elastic electrode films with fluoroelastomer substrates prepared by Examples 11 to 13 show the electrical properties of the electrodes. It can be seen from the figure that the electromechanical properties of the electrode can be controlled by adjusting the electrode thickness by controlling the spin coating speed. When the spin coating speed is 1000 rpm, the resistance change of the electrode is relatively small under large strain conditions.

[0088] Example 14:

[0089] 0.0130 g of PEGDE6K was mixed with 1 g of PEDOT:PSS suspension and stirred with Vortex for 1 h. The mixture was then spin-coated onto a fluoroelastomer substrate at 1000 rpm and heated at 120 °C for 30 min. After peeling, the mixture was spin-coated onto the reverse side at the same speed and heated at 120 °C for 30 min to prepare a sandwich-structured elastic capacitive strain sensor. The mechanical properties and capacitive response of the prepared capacitive strain sensor are shown in Figure 8.

[0090] As shown in Figure 8, the capacitive strain sensor with PEDOT:PSS as the elastic electrode film prepared by the method of Example Fourteen exhibits the electromechanical properties. Figure a represents the stress-strain recovery curve of the capacitive strain sensor, Figure b represents the capacitance change rate and cyclic performance of the capacitive strain sensor under different strains, Figure c represents the relationship between the capacitance change rate and strain of the capacitive strain sensor, and Figure d represents the cyclic performance of the capacitive strain sensor under 30% and 50% strain. It can be seen from the figures that the capacitive strain sensor prepared with cross-linked PEDOT:PSS elastic electrode has stable mechanical recovery performance and good linear response to strain. After multiple cycles, it can still maintain stable strain sensing.

[0091] Therefore, the preparation process of this invention utilizes the addition of different amounts of soft segment crosslinking agents and the application of different crosslinking temperatures to generate PEDOT:PSS elastic electrodes with different mechanical and electrical properties, solving the problems of poor elasticity and poor mechanical recovery of PEDOT:PSS. When designing capacitive strain sensors based on this high mechanical and electrical stability PEDOT:PSS elastic electrode prepared by direct covalent crosslinking, it simultaneously possesses excellent mechanical recovery and capacitance change response, providing new possibilities for the application of this elastic electrode in the field of flexible electronics.

[0092] While the disclosure is as stated above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of this disclosure, and all such changes and modifications will fall within the protection scope of this invention.

Claims

1. A method for preparing a covalently cross-linked PEDOT:PSS elastic electrode, characterized in that, Includes the following steps: Step S1: A water-soluble / water-dispersible crosslinking agent containing dual-terminal active functional groups, a PEDOT:PSS water dispersion solution, and a conductive additive are injected into a container for blending to obtain a mixed solution; Step S2 involves coating the mixed solution onto a substrate, followed by drying and covalent cross-linking to obtain a PEDOT:PSS elastic electrode. In step S1, the dual-terminal active functional groups of the water-soluble / water-dispersible cross-linking agent are any one of epoxy, azide, or bis(acrylidine) functional groups. In step S2, after stirring the mixed solution in Vortex, it is cast onto a 2.5cm*7.5cm glass slide for aeration and drying, followed by drying in a vacuum drying oven at 60°C. The mixture is then dried at 120°C to allow the dual-terminal active functional groups to undergo a covalent cross-linking reaction with the molecular chains in the PEDOT:PSS aqueous dispersion solution, resulting in PEDOT:PSS elastic electrodes with different cross-linking agent contents. In step S1, the main chain structure of the water-soluble / water-dispersible cross-linking agent is any one of polyethylene glycol, polypropylene glycol, polyacrylamide, polyvinyl alcohol, polyacrylic acid, and polyvinylpyrrolidone, and the main chain molecular weight range of the main chain structure is 500~100000 Da.

2. The method for preparing a PEDOT:PSS elastic electrode according to claim 1, characterized in that, In step S1, the conductive additive is any one of dimethyl sulfoxide, ethylene glycol, ionic liquid, and surfactant.

3. The method for preparing a PEDOT:PSS elastic electrode according to claim 1, characterized in that, In step S2, the coating process of the mixed solution is any one of solution drop casting, blade coating, spin coating, or mold coating.

4. The method for preparing a PEDOT:PSS elastic electrode according to claim 1, characterized in that, In step S2, the substrate is any one of glass sheet, silicon wafer, ceramic sheet, PET sheet, and elastomer film.

5. The method for preparing a PEDOT:PSS elastic electrode according to claim 1, characterized in that, In step S2, the thickness of the substrate is 50nm~2mm.

6. The method for preparing a PEDOT:PSS elastic electrode according to claim 1, characterized in that, In step S2, the method of drying the blended film is either ventilation drying or vacuum drying.

7. The method for preparing a PEDOT:PSS elastic electrode according to claim 1, characterized in that, In step S2, the covalent crosslinking treatment of the blended membrane further includes: performing thin-film vacuum heat treatment or heating plate heat treatment on the blended membrane at a temperature of 60℃~200℃.

8. The method for preparing a PEDOT:PSS elastic electrode according to claim 1, characterized in that, After performing step S2, the method further includes treating the PEDOT:PSS elastic electrode with concentrated sulfuric acid or methanol.

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