Preparation method of high conductivity PEDOT:PSS conductive framework

Abstract

This invention discloses a method for preparing a high-conductivity PEDOT:PSS conductive framework, comprising: filtering an aqueous solution of PEDOT:PSS; adding an anionic surfactant to separate the PEDOT:PSS phase and reduce the surface activity of the solution, obtaining a mixed solution; adding the mixed solution and air in a predetermined ratio to a dual-syringe mixing container, mixing and shearing to obtain a PEDOT:PSS foam emulsion; adding the obtained foam emulsion to a specific template and allowing it to slowly solidify; washing the solidified PEDOT:PSS foam with water to remove the surfactant and some PSS; and finally freeze-drying to remove moisture to obtain a high-conductivity PEDOT:PSS conductive framework. The PEDOT:PSS conductive framework prepared by this invention exhibits excellent water / oil stability, higher conductivity, lower framework density, and superior mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of conductive material preparation technology, specifically relating to a method for preparing a high-conductivity PEDOT:PSS conductive framework. Background Technology

[0002] In recent years, conductive framework materials have attracted great attention from academia and industry due to their potential applications in tissue engineering, sensors, and other fields. The conductive components in conductive framework materials mainly include metal-based or carbon-based materials and conductive polymer materials. Compared to metal and carbon-based materials, conductive polymer materials (such as polyaniline, poly(3,4-ethylenedioxythiophene:polystyrene sulfonate (PEDOT:PSS), and polypyrrole) have Young's modulus that better matches biological tissues, better stretchability, more diverse processing methods, and tunable conductivity, making them ideal materials for constructing conductive frameworks.

[0003] PEDOT:PSS conductive frameworks have been extensively studied due to their high conductivity and excellent chemical and environmental stability. PEDOT:PSS conductive frameworks are typically prepared from commercially available PEDOT:PSS dispersions by introducing a crosslinking agent into the dispersion followed by freeze-drying. However, exogenous crosslinking agents hinder the removal of non-conductive PSS components and the rearrangement of conductive PEDOT chains, limiting the conductivity of the resulting PEDOT:PSS conductive framework (typically below 100 S / m). In existing technologies, protic acid or co-solvent post-treatment is the main method for improving the various properties of PEDOT:PSS conductive frameworks. These treatments can weaken the ionic bonds between PEDOT and PSS, allowing the PEDOT-rich structures to physically interconnect under π-π stacking. Combined with high-temperature annealing, the non-conductive PSS chains can be further separated, further improving the conductivity of the conductive framework. However, the solvents introduced in these techniques have certain biotoxicity, which is detrimental to their further application in biosensing. In addition, the PEODT:PSS conductive framework structure prepared by freeze drying has closed channels and mechanical brittleness, and the post-processing steps will further lead to the shrinkage and destruction of the conductive framework structure.

[0004] Therefore, it is still very necessary to develop a method for fabricating a PEDOT:PSS conductive framework with low density, high interconnection channels, and high conductivity. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing a PEDOT:PSS conductive framework with high electrical conductivity.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for preparing a high-conductivity PEDOT:PSS conductive framework, comprising:

[0008] Step S1: Filtration of PEDOT:PSS aqueous solution; Adding anionic surfactant to separate the PEDOT:PSS phase and reduce the surface activity of the solution to obtain a mixed solution;

[0009] Step S2: Add the mixed solution and air to the dual-syringe mixing container in a predetermined ratio, and mix and shear to obtain PEDOT:PSS foam emulsion;

[0010] Step S3: Add the obtained foam emulsion into a specific template and wait for it to slowly cure;

[0011] Step S4: Wash the cured PEDOT:PSS foam with water to remove the surfactant and some PSS;

[0012] Step S5: Freeze-dry to remove moisture to obtain a highly conductive PEDOT:PSS conductive framework.

[0013] Preferably, in step S1, the anionic surfactant has a mass fraction of 0.01 wt% to 10 wt% relative to the mixed solution.

[0014] Preferably, in step S2, the mixed solution and air are added to a dual-syringe mixing container, wherein the air volume accounts for 30%-90% of the total gas-liquid volume, and the piston is repeatedly pushed and pulled to obtain PEDOT:PSS foam emulsion.

[0015] Preferably, in step S1, the original PEDOT:PSS solution is filtered through an aqueous filter to prepare an aqueous solution of 0.1-5 wt%.

[0016] Preferably, a surfactant is used as a foaming agent to form a porous structure. The surfactant in step S1 mainly includes anionic surfactants and neutral surfactants. The anionic surfactants include: deca-hexadecylbenzenesulfonic acid, sodium deca-hexadecyl sulfate, and sodium deca-hexadecyl sulfonate. The neutral surfactants include: polyethylene glycol surfactants and polyvinyl alcohol surfactants.

[0017] Preferably, in step S2, the mixing time of the two syringes is 2-60 minutes.

[0018] Preferably, in step S3, the curing is carried out slowly at room temperature for 20 minutes to 10 hours.

[0019] Preferably, in step S4, the number of water washes is 2-3 times, and the soaking time for each wash is 0.5-1 hour.

[0020] Preferably, the conductivity of the prepared PEDOT:PSS conductive framework is 50S / cm-1000S / cm.

[0021] The present invention has the following advantages:

[0022] 1. The present invention is prepared by physical foaming method, which is simple to operate and the prepared frame has controllable pores, low density, interconnected channels and high stretchability.

[0023] 2. The present invention is prepared by physical crosslinking induced by the separation of PEDOT:PSS phases using anionic surfactants, and has good water / oil stability, low modulus and high conductivity.

[0024] 3. This invention does not use strong acids such as sulfuric acid or biotoxic organic solvents for post-treatment. The conductive framework prepared is green, safe and has good biocompatibility, and has broad application prospects in the field of in vivo and in vitro biosensing. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0026] Figure 1 This is a flowchart illustrating the preparation method of the high-conductivity PEDOT:PSS conductive framework according to an embodiment of the present invention.

[0027] Figure 2 Scanning electron microscope image of the PEDOT:PSS porous framework of this invention;

[0028] Figure 3 The following are comparative data charts of the porosity and pore size of the PEDOT:PSS porous framework of the present invention: (a) is a comparative data chart of the porosity of the PEDOT:PSS porous framework, and (b) is a comparative data chart of the pore size.

[0029] Figure 4 This is a comparison chart of the electrical conductivity of the PEDOT:PSS porous framework of the present invention;

[0030] Figure 5 The mechanical characterization of the PEDOT:PSS porous framework of the present invention is shown in (a) and (b) is the compressive strain data of the conductive framework prepared by the present invention and the compressive strain data of the conductive framework prepared by the conventional freeze-drying method.

[0031] Figure 6This is a graph showing the long-term stability data of the PEDOT:PSS porous framework of the present invention in PBS. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] like Figure 1 As shown, this embodiment of the invention provides a method for preparing a highly conductive PEDOT:PSS conductive framework.

[0035] Step 1: Filter the PEDOT:PSS aqueous solution through an aqueous filter. Add an anionic surfactant to the PEDOT:PSS aqueous solution mixture. The mass fraction of the anionic surfactant relative to the mixture is 0.01wt%-10wt%.

[0036] Step 2: Add the mixed solution and air to the dual-syringe mixing container, wherein the air volume accounts for 30%-90% of the total gas-liquid volume, to obtain PEDOT:PSS foam emulsion. The mixing time is 2-10 minutes.

[0037] Step 3: Add the prepared foam emulsion to the template solution. The surfactant induces the separation of the PEDOT:PSS phases, and physical cross-linking occurs between PEDOT molecules. The emulsion is slowly cured at room temperature for 20 min to 10 h.

[0038] Step 4: Wash and soak the cured PEDOT:PSS skeleton with water 2-3 times, with an interval of 0.5h-1h each time, to remove surfactants and PSS;

[0039] Step 5: Finally, freeze-dry to obtain a highly conductive PEDOT:PSS conductive framework.

[0040] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited thereto.

[0041] Example 1: A method for preparing a highly conductive PEDOT:PSS conductive framework, comprising the following steps

[0042] (1) PEDOT:PSS aqueous solution is filtered through an aqueous filter, and dodecylbenzenesulfonic acid is added to the PEDOT:PSS aqueous solution mixture, wherein the mass fraction of dodecylbenzenesulfonic acid relative to the mixture is 5 wt%.

[0043] (2) Add the mixed solution and air into a double-syringe mixing sealed container, wherein the air volume accounts for 50% of the total gas-liquid volume, and mix rapidly for 4 minutes to obtain PEDOT:PSS foam emulsion;

[0044] (3) The obtained foam emulsion was added to the template solution, and the surfactant induced the separation of the PEDOT:PSS phase and cured slowly at room temperature for 10 hours.

[0045] (4) Wash and soak the solidified porous skeleton with water 2-3 times, with an interval of 0.5h each time, to remove surfactants and PSS;

[0046] (5) Finally, freeze-drying is performed to remove moisture and obtain a highly conductive PEDOT:PSS conductive framework.

[0047] Example 2

[0048] (1) Step (1) is the same as step (1) in Example 1;

[0049] (2) Add the mixed solution and air into a double-syringe mixing sealed container, wherein the air volume accounts for 60% of the total gas-liquid volume, and mix rapidly for 4 minutes to obtain PEDOT:PSS foam emulsion;

[0050] (3) Steps (3) to (5) are the same as steps (3)-(5) in Example 1.

[0051] Example 3

[0052] (1) Step (1) is the same as step (1) in Example 1;

[0053] (2) Add the mixed solution and air into a dual-syringe mixing container, wherein the air volume accounts for 70% of the total gas-liquid volume, and mix rapidly for 4 minutes to obtain PEDOT:PSS foam emulsion;

[0054] (3) Steps (3) to (5) are the same as steps (3)-(5) in Example 1.

[0055] Example 4

[0056] (1) Step (1) is the same as step (1) in Example 1;

[0057] (2) Add the mixed solution and air into a double-syringe mixing sealed container, wherein the air volume accounts for 80% of the total gas-liquid volume, and mix rapidly for 4 minutes to obtain PEDOT:PSS foam emulsion;

[0058] (3) Steps (3) to (5) are the same as steps (3)-(5) in Example 1.

[0059] Example 5

[0060] (1) Step (1) is the same as step (1) in Example 1;

[0061] (2) Add the mixed solution and air into a double-syringe mixing sealed container, wherein the air volume accounts for 90% of the total gas-liquid volume, and mix rapidly for 4 minutes to obtain PEDOT:PSS foam emulsion;

[0062] (3) Steps (3) to (5) are the same as steps (3)-(5) in Example 1.

[0063] Comparative Example 1: A method for preparing a PEDOT:PSS conductive framework by freeze-drying, comprising:

[0064] (1) PEDOT:PSS aqueous solution is filtered through a water system filter;

[0065] (2) After freezing the filtered PEDOT:PSS solution in a refrigerator, freeze-dry it to obtain the PEDOT:PSS conductive framework.

[0066] Figure 2 The images shown are scanning electron microscope (SEM) images of the PEDOT:PSS porous framework of this invention. They reveal that the foam-processed PEDOT:PSS porous framework exhibits a macroscopically and microscopically interconnected porous structure. The conductive polymer PEDOT:PSS condenses into uniform macroscopic pores along the gaps between bubbles. Under the guidance of an ice template, the condensed PEDOT:PSS at these gaps exhibits micropores. As the gas volume fraction increases, the solution decreases at the foam gaps, making the foam easier to coarsen, resulting in thinner pore walls and larger pore sizes. In contrast, freeze-dried PEDOT:PSS exhibits a loose and disordered non-interconnected porous structure.

[0067] Figure 3 a and Figure 3Figure b shows a comparison of porosity and pore size statistics for the PEDOT:PSS porous framework of this invention. As the gas volume fraction increases, the porosity of the PEDOT:PSS porous framework initially increases and then remains above 99%. This is because the increased gas volume fraction reduces the solid density of the framework, leading to increased porosity. However, excessively low solid density causes the framework to collapse during fabrication due to insufficient support for its morphology. With increasing gas volume fraction, the average pore size of the PEDOT:PSS porous framework shows a linear increasing trend, ranging from a minimum of 50 μm to a maximum of 260 μm.

[0068] Figure 4 This is a comparison of the electrical conductivity of the PEDOT:PSS porous framework of the present invention. By introducing anionic surfactants, the PEDOT:PSS porous framework exhibits higher electrical conductivity, reaching up to 800 S / cm, while the conductivity of the PEDOT:PSS porous framework without anionic surfactants is only 0.5 S / cm. This is because the addition of anionic surfactants causes phase separation in PEDOT:PSS, resulting in the separation of some PSS chains from PEDOT chains. The PEDOT-rich structures then physically interconnect under π-π stacking, forming new conductive pathways and achieving higher conductivity.

[0069] Figure 5 For the mechanical characterization of the PEDOT:PSS porous framework of the present invention, Figure 5 Figure 'a' shows the compressive strain data of the conductive frame prepared in Example 3. It can be seen that after 500 compression cycles, the maximum stress did not decrease significantly and maintained good resilience, indicating that the PEDOT:PSS porous frame prepared in this invention has excellent mechanical properties and fatigue resistance. In contrast, the conductive frame prepared by the ordinary freeze-drying method exhibits significant plastic deformation after the first compression, and after 500 compression cycles, the maximum stress of the frame decreases significantly. Figure 5 As shown in b.

[0070] Figure 6 This is a graph showing the long-term stability of the PEDOT:PSS porous framework of the present invention in PBS. The PEDOT:PSS porous framework of the present invention can maintain long-term stability in an aqueous environment. We stored it in PBS for 28 days and tested its charge injection capability on day 1, day 7, and day 28. It can be seen that the charge injection capability of the PEDOT:PSS porous framework of the present invention did not decrease significantly after 28 days, indicating that the PEDOT:PSS porous framework of the present invention has good water stability.

[0071] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a high-conductivity PEDOT:PSS conductive framework, characterized in that, include: Step S1: Filtration of PEDOT:PSS aqueous solution; Adding anionic surfactant to separate the PEDOT:PSS phase and reduce the surface activity of the solution to obtain a mixed solution; Step S2: Add the mixed solution and air to the dual-syringe mixing container in a predetermined ratio, and mix and shear to obtain PEDOT:PSS foam emulsion; Step S3: Add the obtained foam emulsion into a specific template and wait for it to slowly cure; Step S4: Wash the cured PEDOT:PSS foam with water to remove the surfactant and some PSS; Step S5: Freeze-dry to remove moisture to obtain a highly conductive PEDOT:PSS conductive framework; In step S1, the anionic surfactant has a mass fraction of 0.01 wt% - 10 wt% relative to the mixed solution. In step S2, the mixed solution and air are added to a dual-syringe mixing container, wherein the air volume accounts for 30%-90% of the total gas-liquid volume, and the piston is repeatedly pushed and pulled to obtain PEDOT:PSS foam emulsion; In step S1, the original PEDOT:PSS solution is filtered through an aqueous filter to prepare an aqueous solution of 0.1-5 wt%. A porous structure is formed by using surfactants as foaming agents. The surfactants in step S1 include anionic surfactants and neutral surfactants. The anionic surfactants include: deca-hexadecylbenzenesulfonic acid, sodium deca-hexadecyl sulfate, and sodium deca-hexadecyl sulfonate. The neutral surfactants include: polyethylene glycol and polyvinyl alcohol surfactants. In step S2, the mixing time of the two syringes is 2-60 minutes; In step S3, the material is slowly cured at room temperature for 20 min to 10 h. In step S4, the number of water washes is 2-3 times, and the soaking time for each wash is 0.5-1 hour. The conductivity of the prepared PEDOT:PSS conductive framework is 50 S / cm-1000 S / cm.

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