A high-modulus high-conductivity pedot:pss hydrogel, and a preparation method and application thereof

Abstract

This application discloses a high-modulus, high-conductivity PEDOT:PSS hydrogel, its preparation method, and its applications, belonging to the field of flexible conductive hydrogel technology. This application describes the preparation of PEDOT:PSS hydrogel by soaking it in an aqueous acrylic acid solution with a mass concentration greater than 30 wt%. Using an aqueous acrylic acid solution with a mass concentration greater than 30 wt% as the treatment reagent, this application constructs a multiple synergistic mechanism of "removing insulating components, inducing network contraction, and promoting conductive chain rearrangement," thereby effectively achieving a simultaneous and efficient improvement in the storage modulus and conductivity of the PEDOT:PSS hydrogel. This successfully solves the key problem of balancing conductivity and mechanical properties. Simultaneously, it maintains excellent long-term biocompatibility in the PEDOT:PSS hydrogel, providing a new solution for the development of flexible conductive hydrogels in flexible electronics, biomedical sensing, and other fields, and possessing significant potential for industrial application.

Description

Technical Field

[0001] This application belongs to the field of flexible conductive hydrogel technology, specifically a high-modulus, high-conductivity PEDOT:PSS hydrogel, its preparation method, and its application. Background Technology

[0002] The development of flexible conductive hydrogels requires a combination of excellent flexibility, high conductivity, and good biocompatibility to achieve mechanical and electrical compatibility with human tissues, thereby promoting their practical applications in wearable electronics, soft robotics, and biomedical sensing. However, traditional strategies typically involve composite rigid conductive fillers into the flexible hydrogel matrix, often resulting in discontinuous interfacial conductive pathways and weak interfacial bonding. This makes it difficult to simultaneously improve mechanical and conductive properties, and also limits long-term biocompatibility. Therefore, the design and fabrication of flexible conductive hydrogels that simultaneously improve mechanical and conductive properties while also possessing good biocompatibility has attracted considerable attention.

[0003] Constructing integrated hydrogel networks using conductive polymers such as PEDOT:PSS (poly(3,4-ethylenedioxythiophene):polystyrene sulfonate) has become an effective strategy for addressing both conductivity continuity and structural uniformity. However, while the original PEDOT:PSS hydrogel possesses intrinsic conductivity and biocompatibility, its insufficient intrinsic conductivity and brittleness under dynamic deformation limit its application in real-world scenarios. Currently, related technologies disclose a modification strategy involving acid immersion treatment. This involves immersing the original PEDOT:PSS hydrogel in hydrochloric acid, sulfuric acid, etc., to remove the insulating PSS components through acid corrosion and promote the rearrangement and densification of PEDOT conductive chains, thereby simultaneously improving both mechanical and conductive properties.

[0004] However, existing acid immersion post-treatment techniques not only damage the gel network structure, limiting the improvement of mechanical and electrical properties, but also may introduce biotoxic residues, reducing biocompatibility. This makes it difficult for hydrogels to efficiently balance conductivity, mechanical properties, and biocompatibility, failing to meet the comprehensive requirements of biomedical applications for flexible hydrogels in terms of conductivity, mechanical modulus, and long-term biocompatibility. Therefore, developing mild and efficient post-treatment techniques has become a critical issue that urgently needs to be addressed. Summary of the Invention

[0005] This application discloses a high-modulus, high-conductivity PEDOT:PSS hydrogel, its preparation method, and its application. By immersing the original PEDOT:PSS hydrogel in an acrylic acid aqueous solution with a mass concentration greater than 30wt%, the technical problem of existing acid immersion post-treatment technology being unable to efficiently balance conductivity, mechanical properties, and biosafety is effectively solved.

[0006] To achieve the above objectives, the technical solution provided in this application is as follows:

[0007] The first aspect of this application provides a high-modulus, high-conductivity PEDOT:PSS hydrogel, which is prepared by soaking the original PEDOT:PSS hydrogel in an aqueous acrylic acid solution.

[0008] The mass concentration of the acrylic acid aqueous solution is greater than 30 wt%.

[0009] According to the preferred disclosure of the first aspect, the mass concentration of the acrylic acid aqueous solution is 50~100wt%.

[0010] According to the preferred disclosure of the first aspect, the soaking post-treatment time is 24 hours or more.

[0011] According to the preferred disclosure of the first aspect, the post-immersion treatment includes:

[0012] The original PEDOT:PSS hydrogel was immersed in an acrylic acid aqueous solution for high-frequency liquid exchange more than 3 times. The high-frequency liquid exchange frequency was once every 10-15 minutes with fresh acrylic acid aqueous solution.

[0013] The PEDOT:PSS hydrogel, after being treated by high-frequency liquid exchange, was immersed in an acrylic acid aqueous solution for low-frequency liquid exchange more than 3 times. The low-frequency liquid exchange frequency was once every 6 to 8 hours with fresh acrylic acid aqueous solution.

[0014] After the low-frequency solution exchange and soaking process is completed, the hydrogel product is washed with deionized water 5 to 8 times.

[0015] According to the preferred disclosure of the first aspect, the original PEDOT:PSS hydrogel is prepared by gelation of a mixture of PEDOT:PSS aqueous dispersion and dodecylbenzenesulfonic acid.

[0016] According to the preferred disclosure of the first aspect, the solid content of the PEDOT:PSS aqueous dispersion is 1.0~1.3wt%.

[0017] According to the preferred disclosure of the first aspect, the volume ratio of the PEDOT:PSS aqueous dispersion to the dodecylbenzenesulfonic acid is 20:1.

[0018] According to the preferred disclosure of the first aspect, the high-modulus, high-conductivity PEDOT:PSS hydrogel comprises:

[0019] (1) Conductivity above 10 S / cm;

[0020] (2) Energy storage modulus above 10 kPa;

[0021] (3) Cell survival rate of over 90%.

[0022] The second aspect of this application also discloses a method for preparing the high-modulus, high-conductivity PEDOT:PSS hydrogel described in this application, which includes the following steps:

[0023] Preparation of original PEDOT:PSS hydrogel;

[0024] The original PEDOT:PSS hydrogel was immersed in an acrylic acid aqueous solution for high-frequency liquid exchange more than 3 times. The high-frequency liquid exchange frequency was once every 10-15 minutes with fresh acrylic acid aqueous solution.

[0025] The PEDOT:PSS hydrogel, after being treated by high-frequency liquid exchange, was immersed in an acrylic acid aqueous solution for low-frequency liquid exchange more than 3 times. The low-frequency liquid exchange frequency was once every 6 to 8 hours with fresh acrylic acid aqueous solution.

[0026] After the low-frequency solution exchange and soaking process is completed, the hydrogel product is washed with deionized water 5 to 8 times.

[0027] The third aspect of this application also discloses the application of the high modulus and high conductivity PEDOT:PSS hydrogel described in this application, specifically the use of the high modulus and high conductivity PEDOT:PSS hydrogel in flexible electronic devices, wearable sensors, biomedical electrodes, tissue engineering scaffolds, etc. Flexible electronic devices include, but are not limited to, conductive connection components for flexible circuit boards and flexible displays, conductive materials for flexible energy storage devices (such as conductive electrode materials for flexible supercapacitors and flexible lithium-ion batteries), and conductive driving layers for flexible electrochromic devices; wearable sensors include, but are not limited to, physiological signal sensors (such as dry / wet electrodes for ECG, EMG, and EEG sensors), motion state sensors (such as deformation-sensitive elements for joint flexion and muscle stretching sensors), and health monitoring sensors (such as conductive sensing substrates for sweat pH, glucose, and lactic acid sensors); biomedical electrodes include, but are not limited to, implantable electrodes (such as conductive contacts for nerve stimulation electrodes and cardiac pacing electrodes), in vitro diagnostic electrodes (such as detection electrodes for ECG and EEG electrodes), and electrodes for tissue electrophysiological research (such as conductive modification layers for extracellular recording electrodes); and tissue engineering scaffolds include, but are not limited to, conductivity-dependent tissue repair scaffolds such as neural tissue engineering scaffolds, muscle tissue engineering scaffolds, and myocardial tissue engineering scaffolds.

[0028] Compared with the prior art, the advantages or beneficial effects of this application include at least:

[0029] This application creatively utilizes an aqueous solution of acrylic acid, which selectively interacts with insulating PSS components and has a matching structural polarity, to soak and treat the original PEDOT:PSS hydrogel. This process causes the excess and / or randomly distributed PSS components in the PEDOT:PSS hydrogel network to be directionally exfoliated / dissolved. This effectively weakens the insulating barrier between PEDOT conductive chains and induces a moderate and uniform volume shrinkage of the gel network while simultaneously rearranging the PEDOT conductive chains in an ordered manner. This results in a denser and more continuous conductive gel network, thereby achieving a high degree of conductivity based on the selective interaction between acrylic acid and PSS components and the structural... The polarity matching mechanism forms a multi-synergistic effect mechanism of "removing insulating components, inducing network contraction, and promoting conductive chain rearrangement," ultimately achieving a simultaneous and efficient improvement in the conductivity and storage modulus of PEDOT:PSS hydrogel. This successfully solves the key problem of balancing conductivity and mechanical properties. At the same time, it avoids the introduction / residue of biotoxicity and the destruction of the gel network structure, enabling PEDOT:PSS hydrogel to maintain excellent long-term biocompatibility. This provides a new solution for the development of flexible conductive hydrogels in fields such as flexible electronics and biomedical sensing, and has significant potential for industrial application. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 SEM images of the original PEDOT:PSS hydrogel and AA(100%)-PEDOT:PSS hydrogel provided for this application (a and b are SEM images of the original PEDOT:PSS hydrogel and AA(100%)-PEDOT:PSS hydrogel, respectively).

[0032] Figure 2 A statistical chart of the diameter dimensions of each hydrogel sample provided in this application;

[0033] Figure 3 The diagrams show the dynamic rheological properties of the hydrogel samples provided in this application. af corresponds to HCl-PEDOT:PSS hydrogel, original PEDOT:PSS hydrogel, AA(30%)-PEDOT:PSS hydrogel, AA(50%)-PEDOT:PSS hydrogel, AA(80%)-PEDOT:PSS hydrogel and AA(100%)-PEDOT:PSS hydrogel, respectively (G' is the storage modulus and G" is the energy dissipation modulus).

[0034] Figure 4 A statistical chart of the storage modulus of each hydrogel sample provided in this application;

[0035] Figure 5 The statistical graphs of average resistance and conductivity of each hydrogel sample provided in this application are shown in Figure 1 (a is the statistical graph of average resistance of each hydrogel sample, and b is the statistical graph of conductivity of each hydrogel sample).

[0036] Figure 6 The resistance curve of the AA(100%)-PEDOT:PSS hydrogel provided in this application as a function of time;

[0037] Figure 7 This is a statistical chart showing the relative cell viability of each hydrogel sample in this application. Detailed Implementation

[0038] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments described in this application without creative effort are within the scope of protection of this application.

[0039] In the following description of this application, the term "and / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, B existing alone, and A and B existing simultaneously. Here, A and B can be singular or plural; the symbol " / " means "or".

[0040] In the following description of this application, the term "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions mean any combination of such items, including any combination of single or multiple items. For example, "at least one of A, B or C" or "at least one of A, B and C" can mean any one of A, B, and C, or A+B, or A+C, or B+C, or A+B+C, where A, B, and C can be single or multiple.

[0041] In the following description of this application, the order of the sequence numbers does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be specifically determined by its function and internal logic, and does not constitute any limitation on the execution process of this embodiment.

[0042] In the following description of this application, the numerical range should be understood to also specifically disclose each intermediate value between the upper and lower limits of the range. Any intermediate value within a stated range, as well as any other stated value or each smaller range between intermediate values ​​within a stated range, are also included in this embodiment, and the upper and lower limits of the smaller ranges may be independently included or excluded from the range.

[0043] Unless otherwise stated, the technical / scientific terms used in this application have the meanings commonly understood by one of ordinary skill in the art. While this application describes only preferred materials and methods, similar or equivalent methods and materials may be used in specific embodiments or test cases. All references to this application are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this application shall prevail.

[0044] To address the problem that existing acid immersion post-treatment techniques are difficult to efficiently balance conductivity, mechanical properties, and biosafety, the first aspect of this application provides a high-modulus, high-conductivity PEDOT:PSS hydrogel, which is prepared by immersing the original PEDOT:PSS hydrogel in an acrylic acid aqueous solution, wherein the mass concentration of the acrylic acid aqueous solution is greater than 30 wt%.

[0045] This application embodiment utilizes acrylic acid, which selectively interacts with the insulating PSS component and has a matching structural polarity, as an acid treatment agent to immerse the original PEDOT:PSS hydrogel in a post-treatment process. This allows for the directional stripping / dissolution of excess and / or randomly distributed PSS components in the PEDOT:PSS hydrogel network. Firstly, this effectively weakens the insulating barrier between PEDOT conductive chains, making the transport path of conductive carriers smoother and improving carrier migration efficiency from the source, thus initially increasing conductivity. Secondly, it promotes the ordered rearrangement of PEDOT conductive chains while inducing moderate and uniform volume shrinkage of the gel network, making the conductive gel network denser and more continuous. This significantly increases the number and integrity of conductive pathways, resulting in a step-like increase in conductivity while avoiding the problem of excessive removal of the insulating PSS component causing damage to the gel network structure. This ensures the gel network structure remains intact, fundamentally solving the problem of limited improvement in mechanical and conductive properties in existing acid immersion post-treatment technologies. The problem of "significantly increasing the energy storage modulus of PEDOT:PSS hydrogel while maintaining good flexibility and resistance to deformation" is addressed by leveraging the unique selective interaction and structural polarity matching between acrylic acid and PSS components to jointly construct a multi-synergistic mechanism of "removing insulating components - inducing network contraction - promoting conductive chain rearrangement." This ultimately achieves a simultaneous and efficient increase in the conductivity and energy storage modulus of PEDOT:PSS hydrogel, successfully solving the problem of balancing the conductivity and mechanical properties of PEDOT:PSS hydrogel. Simultaneously, the mild acrylic acid post-treatment avoids the introduction / residue of biotoxicity and prevents damage to the gel network structure, reducing the problem of immune reactions caused by microparticle detachment and deposition due to gel network damage. This ensures that PEDOT:PSS hydrogel maintains excellent long-term biocompatibility, providing a new solution for the development of flexible conductive hydrogels in flexible electronics, biomedical sensing, and other fields, and has significant potential for industrial application.

[0046] In possible disclosed examples, the mass concentration of the acrylic acid aqueous solution described in this application is preferably 50-100 wt%, thereby optimizing the synergistic efficiency of "removing insulating components-inducing network shrinkage-promoting conductive chain rearrangement," resulting in a superior simultaneous improvement in the conductivity and storage modulus of the PEDOT:PSS hydrogel while ensuring biocompatibility. The embodiments of this application use 50 wt%, 80 wt%, and 100 wt% as representative examples because these three concentration groups respectively cover the lower, middle, and upper limits of the selectable range of this application, enabling comprehensive and intuitive verification of the technical effects within this concentration range, facilitating understanding by those skilled in the art. However, this does not constitute any limitation on the scope of protection of this application. Any other concentration ratio falling within the 50-100 wt% range is within the scope of protection of this application, and will not be listed individually here.

[0047] In possible disclosed examples, the post-immersion treatment time described in this application is preferably 24 hours or more, thereby ensuring that the PSS components are sufficiently and directionally exfoliated / dissolved, achieving simultaneous optimization of conductivity, storage modulus, and biocompatibility. The embodiment in this application uses 24 hours as a representative example for illustrative description because...

[0048] This parameter can take into account both verification efficiency and the ability to comprehensively and intuitively verify the core effect of the technical solution, making it easy for those skilled in the art to understand. However, this does not constitute any limitation on the scope of protection of this application. Other time parameters that fall within the range of 24 hours or more (such as 36 hours) are all within the scope of protection of this application, and will not be listed one by one here.

[0049] In possible disclosed examples, the post-immersion treatment described in this application preferably includes:

[0050] The original PEDOT:PSS hydrogel was immersed in an acrylic acid aqueous solution for high-frequency liquid exchange more than 3 times. The high-frequency liquid exchange frequency was once every 10-15 minutes with fresh acrylic acid aqueous solution.

[0051] The PEDOT:PSS hydrogel, after being treated by high-frequency liquid exchange, was immersed in an acrylic acid aqueous solution for low-frequency liquid exchange more than 3 times. The low-frequency liquid exchange frequency was once every 6 to 8 hours with fresh acrylic acid aqueous solution.

[0052] After the low-frequency solution exchange and soaking process is completed, the hydrogel product is washed with deionized water 5 to 8 times.

[0053] It should be noted that the above two-step soaking treatment in this application embodiment can synergistically improve the penetration efficiency and ensure the uniformity of modification, providing a basis for the simultaneous optimization of electrical conductivity and mechanical properties. Multiple washings with deionized water can remove unreacted free monomers and by-products, improving the purity of the final gel product.

[0054] In possible public examples, the original PEDOT:PSS hydrogel described in this application is prepared by gelation of a mixture of PEDOT:PSS aqueous dispersion and dodecylbenzenesulfonic acid. Preferably, the PEDOT:PSS aqueous dispersion is stirred at room temperature until a uniformly dispersed prepolymer is formed, then dodecylbenzenesulfonic acid (DBSA) is added and the mixture is shaken and mixed for 1 minute. Finally, the resulting mixture is injected into a mold and allowed to stand at room temperature until a three-dimensional network structure hydrogel is formed.

[0055] It should be noted that the PEDOT:PSS hydrogel doped with dodecylbenzenesulfonic acid is selected as the representative example in this application for illustrative description because dodecylbenzenesulfonic acid can mildly induce polymer chain crosslinking to form a three-dimensional gel network and moderately improve conductivity, which facilitates clear verification of the core synergistic mechanism of "removing insulating components - inducing network contraction - promoting conductive chain rearrangement" in this application. However, this does not constitute any limitation on the scope of protection of this application. Any other commonly used dopants that can achieve the doping effect of this application also fall within the scope of protection of this application, and will not be listed one by one in this application.

[0056] In possible public examples, the solid content of the PEDOT:PSS aqueous dispersion described in this application is preferably 1.0~1.3wt%, because this range can ensure the concentration of polymer chains required for gelation of the dispersion, which helps to form a continuous and stable gel network, while avoiding excessive viscosity of the system and difficulty in monomer penetration due to excessive solid content, and preventing the network from being sparse and the mechanical and electrical properties from being insufficient due to excessively low solid content.

[0057] In possible public examples, the volume ratio of the PEDOT:PSS aqueous dispersion to the dodecylbenzenesulfonic acid is preferably 20:1, because this ratio can balance doping efficiency, gelation uniformity and system stability, and improve the mechanical properties of the gel network structure.

[0058] In possible disclosed examples, the high-modulus, high-conductivity PEDOT:PSS hydrogel preferably possesses:

[0059] (1) Conductivity above 10 S / cm;

[0060] (2) Energy storage modulus above 10 kPa;

[0061] (3) Cell survival rate of over 90%.

[0062] The second aspect of this application also provides a method for preparing the high-modulus, high-conductivity PEDOT:PSS hydrogel described above, preferably comprising the following steps:

[0063] Preparation of original PEDOT:PSS hydrogel;

[0064] The original PEDOT:PSS hydrogel was immersed in an acrylic acid aqueous solution for high-frequency liquid exchange more than 3 times. The high-frequency liquid exchange frequency was once every 10-15 minutes with fresh acrylic acid aqueous solution.

[0065] The PEDOT:PSS hydrogel, after being treated by high-frequency liquid exchange, was immersed in an acrylic acid aqueous solution for low-frequency liquid exchange more than 3 times. The low-frequency liquid exchange frequency was once every 6 to 8 hours with fresh acrylic acid aqueous solution.

[0066] After the low-frequency solution exchange and soaking process is completed, the hydrogel product is washed with deionized water 5 to 8 times.

[0067] The preparation method provided in this application involves soaking the original PEDOT:PSS hydrogel in mild acrylic acid as a post-treatment. Based on the selective interaction between acrylic acid and PSS components and the matching of structural polarities, a multi-synergistic mechanism of "removing insulating components, inducing network shrinkage, and promoting conductive chain rearrangement" is jointly constructed. This ultimately achieves a simultaneous and efficient improvement in the conductivity and storage modulus of the PEDOT:PSS hydrogel, successfully solving the key problem of balancing conductivity and mechanical properties. At the same time, the process is mild and easy to operate, avoiding the damage to the gel network structure and the introduction of biotoxicity caused by strong acid post-treatment, so that the PEDOT:PSS hydrogel still maintains excellent biocompatibility.

[0068] The third aspect of this application also provides the application of the high modulus and high conductivity PEDOT:PSS hydrogel described above, specifically, the high modulus and high conductivity PEDOT:PSS hydrogel is used for applications including but not limited to flexible electronic devices, wearable sensors, biomedical electrodes, tissue engineering scaffolds, etc. Flexible electronic devices include, but are not limited to, conductive connection components for flexible circuit boards and flexible displays, conductive materials for flexible energy storage devices (such as conductive electrode materials for flexible supercapacitors and flexible lithium-ion batteries), and conductive driving layers for flexible electrochromic devices; wearable sensors include, but are not limited to, physiological signal sensors (such as dry / wet electrodes for ECG, EMG, and EEG sensors), motion state sensors (such as deformation-sensitive elements for joint flexion and muscle stretching sensors), and health monitoring sensors (such as conductive sensing substrates for sweat pH, glucose, and lactic acid sensors); biomedical electrodes include, but are not limited to, implantable electrodes (such as conductive contacts for nerve stimulation electrodes and cardiac pacing electrodes), in vitro diagnostic electrodes (such as detection electrodes for ECG and EEG electrodes), and electrodes for tissue electrophysiological research (such as conductive modification layers for extracellular recording electrodes); and tissue engineering scaffolds include, but are not limited to, conductivity-dependent tissue repair scaffolds such as neural tissue engineering scaffolds, muscle tissue engineering scaffolds, and myocardial tissue engineering scaffolds.

[0069] The technical solution of this application will be further described below with reference to specific embodiments. In the following embodiments of this application, the PEDOT:PSS hydrogel post-treated with hydrochloric acid is abbreviated as "HCl-PEDOT:PSS hydrogel"; the hydrogel post-treated with acrylic acid (AA) aqueous solution is abbreviated as "AA(100%)-PEDOT:PSS hydrogel", "AA(80%)-PEDOT:PSS hydrogel", "AA(50%)-PEDOT:PSS hydrogel" and "AA(30%)-PEDOT:PSS hydrogel" respectively, depending on the concentration of acrylic acid (AA) aqueous solution.

[0070] Example 1

[0071] This example provides an experimental demonstration of the preparation of AA(100%)-PEDOT:PSS hydrogel, specifically including the following steps:

[0072] S1: Take PEDOT:PSS aqueous dispersion (solid content 1.2wt%), and magnetically stir at room temperature and 600rpm for 6 hours to form a uniformly dispersed prepolymer. Add dodecylbenzenesulfonic acid (DBSA, volume ratio of DBSA to PEDOT:PSS dispersion is 1:20) to the prepolymer as a dopant and use a vortex shaker to mix the mixture for 1 minute. Then, take 3mL of the mixture and inject it into a cylindrical mold with a bottom diameter of 35mm. Let it stand at room temperature for 10 minutes to prepare a three-dimensional network structure hydrogel. Finally, take out the solidified hydrogel and immerse it in sufficient deionized water for washing. Change the water every 3 hours and wash it 4 times in total to obtain pure original PEDOT:PSS hydrogel (cylindrical).

[0073] S2: The original PEDOT:PSS hydrogel was immersed in pure acrylic acid (100wt%) for high-frequency liquid exchange three times. The high-frequency liquid exchange frequency was once every 12 minutes.

[0074] S3: PEDOT:PSS hydrogel that has undergone high-frequency liquid exchange soaking is immersed in pure acrylic acid (100wt%) for three low-frequency liquid exchange soaking treatments. The low-frequency liquid exchange frequency is once every 7 hours, with the last low-frequency liquid exchange delayed for a total treatment time of 24 hours.

[0075] S4: After the low-frequency liquid exchange soaking treatment is completed, the gel product is immersed in sufficient deionized water and washed 6 times to completely remove residual acrylic acid. The water is changed once every 3 hours during the process to obtain AA(100%)-PEDOT:PSS hydrogel.

[0076] Example 2

[0077] This example provides an experimental demonstration of the preparation of AA(80%)-PEDOT:PSS hydrogel, specifically including the following steps:

[0078] S1: Take PEDOT:PSS aqueous dispersion (solid content 1.2wt%), and magnetically stir at room temperature and 600rpm for 6 hours to form a uniformly dispersed prepolymer. Add dodecylbenzenesulfonic acid (DBSA, volume ratio of DBSA to PEDOT:PSS dispersion is 1:20) to the prepolymer as a dopant and use a vortex shaker to mix the mixture for 1 minute. Then, take 3mL of the mixture and inject it into a cylindrical mold with a bottom diameter of 35mm. Let it stand at room temperature for 10 minutes to prepare a three-dimensional network structure hydrogel. Finally, take out the solidified hydrogel and immerse it in sufficient deionized water for washing. Change the water every 3 hours and wash it 4 times in total to obtain pure original PEDOT:PSS hydrogel (cylindrical).

[0079] S2: The original PEDOT:PSS hydrogel was immersed in an 80wt% acrylic acid aqueous solution for high-frequency liquid exchange three times. The high-frequency liquid exchange frequency was once every 12 minutes, replacing the solution with a fresh 80wt% acrylic acid aqueous solution.

[0080] S3: The PEDOT:PSS hydrogel after high-frequency liquid exchange soaking is immersed in an 80wt% acrylic acid aqueous solution for low-frequency liquid exchange soaking three times. The low-frequency liquid exchange frequency is once every 7 hours to replace the 80wt% acrylic acid aqueous solution. The last low-frequency liquid exchange is delayed for a total treatment time of 24 hours.

[0081] S4: After the low-frequency liquid exchange soaking treatment is completed, the gel product is immersed in sufficient deionized water and washed 6 times to completely remove residual acrylic acid. The water is changed once every 3 hours during the process to obtain AA(80%)-PEDOT:PSS hydrogel.

[0082] Example 3

[0083] This example provides an experimental demonstration of the preparation of AA(50%)-PEDOT:PSS hydrogel, specifically including the following steps:

[0084] S1: Take PEDOT:PSS aqueous dispersion (solid content 1.2wt%), and magnetically stir at room temperature and 600rpm for 6 hours to form a uniformly dispersed prepolymer. Add dodecylbenzenesulfonic acid (DBSA, volume ratio of DBSA to PEDOT:PSS dispersion is 1:20) to the prepolymer as a dopant and use a vortex shaker to mix the mixture for 1 minute. Then, take 3mL of the mixture and inject it into a cylindrical mold with a bottom diameter of 35mm. Let it stand at room temperature for 10 minutes to prepare a three-dimensional network structure hydrogel. Finally, take out the solidified hydrogel and immerse it in sufficient deionized water for washing. Change the water every 3 hours and wash it 4 times in total to obtain pure original PEDOT:PSS hydrogel (cylindrical).

[0085] S2: The original PEDOT:PSS hydrogel was immersed in a 50wt% acrylic acid aqueous solution for high-frequency liquid exchange three times. The high-frequency liquid exchange frequency was once every 12 minutes, replacing the solution with a fresh 50wt% acrylic acid aqueous solution.

[0086] S3: The PEDOT:PSS hydrogel after high-frequency liquid exchange soaking was immersed in a 50wt% acrylic acid aqueous solution for low-frequency liquid exchange soaking three times. The low-frequency liquid exchange frequency was once every 7 hours, replacing the 50wt% acrylic acid aqueous solution with fresh solution. The last low-frequency liquid exchange was delayed for a total treatment time of 24 hours.

[0087] S4: After the low-frequency liquid exchange soaking treatment is completed, the gel product is immersed in sufficient deionized water and washed 6 times to completely remove residual acrylic acid. The water is changed once every 3 hours during the process to obtain AA(50%)-PEDOT:PSS hydrogel.

[0088] To illustrate the practical effects of the technical solution of this application, comparative examples 1 to 3 are also provided, and the hydrogel products prepared in the examples and comparative examples are characterized.

[0089] Comparative Example 1

[0090] This comparative example provides pure, original PEDOT:PSS hydrogel (cylindrical), prepared using the same process as in Example 1 above.

[0091] Comparative Example 2

[0092] This comparative example provides the preparation experiment of HCl-PEDOT:PSS hydrogel, specifically including the following steps:

[0093] S1: Prepare the original PEDOT:PSS hydrogel (cylindrical) according to the preparation process of Example 1;

[0094] S2: The original PEDOT:PSS hydrogel was immersed in 37wt% concentrated hydrochloric acid for high-frequency liquid exchange three times. The high-frequency liquid exchange frequency was once every 12 minutes, replacing the concentrated hydrochloric acid with fresh 37wt%.

[0095] S3: The PEDOT:PSS hydrogel treated by high-frequency liquid exchange is immersed in 37wt% concentrated hydrochloric acid for three low-frequency liquid exchange treatments. The low-frequency liquid exchange frequency is once every 7 hours, with the last low-frequency liquid exchange delayed for a total treatment time of 24 hours.

[0096] S4: After the soaking treatment with low-frequency liquid exchange is completed, the gel product is immersed in sufficient deionized water and washed 6 times to completely remove residual hydrochloric acid. The water is changed once every 3 hours during the process to obtain HCl-PEDOT:PSS hydrogel.

[0097] Comparative Example 3

[0098] This comparative example provides the preparation experiment of AA(30%)-PEDOT:PSS hydrogel, specifically including the following steps:

[0099] S1: Prepare the original PEDOT:PSS hydrogel (cylindrical) according to the preparation process of Example 1;

[0100] S2: The original PEDOT:PSS hydrogel was immersed in a 30wt% acrylic acid aqueous solution for high-frequency liquid exchange three times. The high-frequency liquid exchange frequency was once every 12 minutes, replacing the solution with a fresh 30wt% acrylic acid aqueous solution.

[0101] S3: The PEDOT:PSS hydrogel after high-frequency liquid exchange soaking was immersed in a 30wt% acrylic acid aqueous solution for low-frequency liquid exchange soaking three times. The low-frequency liquid exchange frequency was once every 7 hours, replacing the 30wt% acrylic acid aqueous solution with fresh solution. The last low-frequency liquid exchange was delayed for a total treatment time of 24 hours.

[0102] S4: After the low-frequency liquid exchange soaking treatment is completed, the gel product is immersed in sufficient deionized water and washed 6 times to completely remove residual acrylic acid. The water is changed once every 3 hours during the process to obtain AA(30%)-PEDOT:PSS hydrogel.

[0103] Test Example 1: Microscopic Morphology and Structural Characterization

[0104] 1.1 SEM characterization

[0105] The network structures of the original PEDOT:PSS hydrogel and AA(100%)-PEDOT:PSS hydrogel were observed using field emission scanning electron microscopy (SEM) as follows:

[0106] First, the original PEDOT:PSS hydrogel and AA(100%)-PEDOT:PSS hydrogel samples were frozen in an ultra-low temperature freezer at -80℃ for more than 12 hours. Then, the frozen samples were transferred to a freeze dryer and dried at -50℃ and a vacuum degree below 10 Pa for 48 hours to remove all moisture and maintain their network morphology. The sample used for observation was the brittle fracture surface of the freeze-dried gel. Specifically, the fracture surface sample was firmly attached to the sample stage with conductive adhesive, and gold sputtering was performed at 10mA for 60 seconds to form a uniform conductive layer on the sample surface. SEM observation was then performed (accelerating voltage 5.0kV, working distance approximately 8.0mm). The results were as follows: Figure 1 As shown. Among them, Figure 1 In the image, a and b are SEM images of the original PEDOT:PSS hydrogel and AA(100%)-PEDOT:PSS hydrogel, respectively.

[0107] according to Figure 1 It can be seen that the original PEDOT:PSS hydrogel exhibits a typical porous three-dimensional network structure with a large pore size; however, after being soaked in pure acrylic acid, the hydrogel network underwent significant shrinkage and densification, and the pore size was significantly reduced.

[0108] 1.2 Quantitative Analysis of Volume Shrinkage Rate

[0109] The diameters of the hydrogel products prepared in Examples 1-3 and Comparative Examples 1-3 were directly measured using vernier calipers (accuracy 0.02 mm). Each sample was measured three times, and the average value was taken to calculate the volume shrinkage rate. The results were statistically analyzed. Figure 2 As shown. Among them, Figure 2 This is a statistical chart showing the diameter dimensions of each hydrogel sample.

[0110] according to Figure 2 It is evident that both soaking in concentrated hydrochloric acid and acrylic acid aqueous solution significantly reduced the pore size of the original PEDOT:PSS hydrogel. Furthermore, the diameter shrinkage rate of the PEDOT:PSS hydrogel treated with acrylic acid aqueous solution was relatively large, with the AA(100%)-PEDOT:PSS hydrogel having the largest diameter shrinkage rate after soaking in acrylic acid aqueous solution.

[0111] Test Example 2: Mechanical Property Test

[0112] The viscoelastic mechanical properties of the hydrogel were quantified using an oscillatory shear test with a high-performance rotational rheometer and a 20mm diameter parallel plate fixture. Before testing, a cylindrical hydrogel sample (initial diameter approximately 35mm) was placed at the center of the lower plate, and the upper plate was slowly lowered until the fixture gap was 1.00mm, with any excess material carefully trimmed. First, a strain scan test was performed: at a fixed frequency of 1Hz, the strain was increased from 0.1% to 100% to determine the linear viscoelastic region of the material. Then, a 1% strain was selected as a safe test condition for subsequent frequency scans. Finally, a frequency scan test was performed: at a fixed strain of 1%, the angular frequency was scanned from 0.1 rad / s to 100 rad / s, and the curves of storage modulus (G') and loss modulus (G'') as a function of frequency were recorded. The results are as follows: Figure 3 As shown. Among them, Figure 3 The figures 'af' represent the dynamic rheological properties of the original PEDOT:PSS hydrogel, HCl-PEDOT:PSS hydrogel, AA(30%)-PEDOT:PSS hydrogel, AA(50%)-PEDOT:PSS hydrogel, AA(80%)-PEDOT:PSS hydrogel, and AA(100%)-PEDOT:PSS hydrogel, respectively. To facilitate a direct comparison of the mechanical strength of each group of samples, the average storage modulus at each point in each group was calculated and compared. At least three parallel samples were tested for each group, and their mean and standard deviation were calculated. The final results are as follows: Figure 4 As shown.

[0113] according to Figure 3 and Figure 4 It is evident that post-treatment with concentrated hydrochloric acid and acrylic acid aqueous solution significantly improves the storage modulus of PEDOT:PSS hydrogel. Specifically, the storage modulus after post-treatment with a 30 wt% acrylic acid aqueous solution is slightly higher than that after treatment with concentrated hydrochloric acid. However, the storage modulus after post-treatment with a 50-100 wt% acrylic acid aqueous solution is significantly higher than that after treatment with concentrated hydrochloric acid, and the storage modulus increases with increasing acrylic acid aqueous solution concentration, reaching its highest value after treatment with pure acrylic acid, and exhibiting the most stable structure during frequency scanning. Therefore, in this application, the mass concentration of the acrylic acid aqueous solution used for post-treatment of the original PEDOT:PSS hydrogel is selected to be greater than 30 wt%, more preferably 50-100 wt%.

[0114] Test Example 3: Electrochemical Performance Test

[0115] 3.1 Conductivity Test

[0116] The DC conductivity of the hydrogel was calculated by measuring its volume resistivity. The volume resistivity was measured using a high-precision digital multimeter with a two-electrode method. Specifically, the treated hydrogel was fabricated into a cylinder of uniform thickness (d), and its sides were tightly clamped between two parallel circular gold electrodes (area A) to ensure good contact and stable contact resistance. The resistance value R of the sample was directly read. At least five independent samples were prepared and tested under each condition, and the average resistance was statistically analyzed. Figure 5 As shown in 'a', the volume conductivity was converted using the formula σ=d / (R×A) for comparative analysis, and the results are as follows: Figure 5 As shown in b in the diagram. Where, Figure 5 In the figure, 'a' represents the statistical graph of the average resistance of each hydrogel sample. Figure 5 In the figure, b represents the conductivity statistics of each hydrogel sample.

[0117] according to Figure 5 It is evident that post-treatment with concentrated hydrochloric acid and acrylic acid aqueous solution significantly improves the conductivity of PEDOT:PSS hydrogel. Specifically, the conductivity after treatment with a 30 wt% acrylic acid aqueous solution is slightly higher than that after treatment with concentrated hydrochloric acid, but the conductivity after treatment with a 50-100 wt% acrylic acid aqueous solution is significantly higher than that after treatment with concentrated hydrochloric acid, and the conductivity increases with increasing acrylic acid aqueous solution concentration, reaching a maximum of 25 S / cm after treatment with pure acrylic acid. Therefore, in this application, the mass concentration of the acrylic acid aqueous solution used for post-treatment of the original PEDOT:PSS hydrogel is selected to be greater than 30 wt%, more preferably 50-100 wt%.

[0118] 3.2 Long-term stability test of conductivity

[0119] This application uses AA(100%)-PEDOT:PSS hydrogel as a test example for verification analysis. Specifically, the AA(100%)-PEDOT:PSS hydrogel was placed in a constant temperature and humidity environment (25°C, 50% RH). Samples were removed at predetermined time points, and their resistance was measured again using the same electrode system and measurement method. The results were plotted as a curve of resistance versus time. Figure 6 As shown. Among them, Figure 6 The resistance curve of AA(100%)-PEDOT:PSS hydrogel changes over time.

[0120] according to Figure 6 It is evident that the resistance value of AA(100%)-PEDOT:PSS hydrogel is very stable in a constant temperature and humidity environment (25°C, 50% RH), and the resistance value increases by no more than 10% within 35 days, indicating that the conductivity of AA(100%)-PEDOT:PSS hydrogel has long-term stability.

[0121] Test Example 4: Biocompatibility Assessment

[0122] The biocompatibility of the material extract was quantitatively evaluated using the CCK-8 cytotoxicity assay (strictly following ISO 10993-5 standards). First, all hydrogel samples were aseptically treated with ultraviolet light (30 minutes per side). Then, the samples were immersed in DMEM complete medium at a ratio of 0.1 g / mL (sample mass to extraction medium volume) for 24 ± 0.5 hours at 37°C and 5% CO2 to prepare a 100% extract, which was then diluted to a 50% concentration with fresh medium. Mouse fibroblast L929 cells were used as test cells, with 1 × 10⁻⁶ cells per well. 4 Cells were seeded at a density of [number] cells per well in 96-well plates and cultured under standard conditions for 24 hours to allow for full cell adhesion. The original culture medium was discarded, and 100 μL of 100% extract, 50% extract, negative control (fresh complete culture medium), and positive control (medium containing 10% DMSO) were added to each well. At least six replicates were set up for each experimental group. The cells were cultured for another 24 hours, and 10 μL of CCK-8 solution was added to each well. The cells were then incubated in the dark for 2 hours. Finally, the absorbance (OD450) of each well was measured at 450 nm using a microplate reader. The relative cell viability was calculated using the formula: [(mean OD450 of experimental groups - mean OD450 of blank wells) / (mean OD450 of negative control group - mean OD450 of blank wells)] × 100%. Figure 6 As shown. Among them, Figure 7 This is a statistical chart showing the relative cell viability of each group of hydrogel samples.

[0123] according to Figure 7 As can be seen, the cell survival rate of the acrylic acid aqueous solution treatment groups was greater than 90%, while the average cell survival rate of the hydrochloric acid treatment group was only 57.3%, indicating the significant superiority of acrylic acid aqueous solution in the biocompatibility of PEDOT:PSS hydrogel.

[0124] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0125] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of this application.

Claims

1. A high-modulus, high-conductivity PEDOT:PSS hydrogel, characterized in that, The original PEDOT:PSS hydrogel was prepared by soaking it in an aqueous acrylic acid solution. The mass concentration of the acrylic acid aqueous solution is 50~100wt%.

2. The high modulus, high conductivity PEDOT:PSS hydrogel according to claim 1, characterized in that, The soaking and post-treatment time is more than 24 hours.

3. The high modulus, high conductivity PEDOT:PSS hydrogel of claim 1, wherein, The post-immersion treatment includes: The original PEDOT:PSS hydrogel was immersed in an acrylic acid aqueous solution for high-frequency liquid exchange more than 3 times. The high-frequency liquid exchange frequency was once every 10-15 minutes with fresh acrylic acid aqueous solution. The PEDOT:PSS hydrogel, after being treated by high-frequency liquid exchange, was immersed in an acrylic acid aqueous solution for low-frequency liquid exchange more than 3 times. The low-frequency liquid exchange frequency was once every 6 to 8 hours with fresh acrylic acid aqueous solution. After the low-frequency solution exchange and soaking process is completed, the hydrogel product is washed with deionized water 5 to 8 times.

4. The high modulus, high conductivity PEDOT:PSS hydrogel according to claim 1, characterized in that, The original PEDOT:PSS hydrogel was prepared by gelation of a mixture of PEDOT:PSS aqueous dispersion and dodecylbenzenesulfonic acid.

5. The high modulus, high conductivity PEDOT:PSS hydrogel of claim 4, wherein, The solid content of the PEDOT:PSS aqueous dispersion is 1.0~1.3wt%.

6. The high modulus, high conductivity PEDOT:PSS hydrogel of claim 5, characterized by, The volume ratio of the PEDOT:PSS aqueous dispersion to the dodecylbenzenesulfonic acid is 20:

1.

7. The high modulus, high conductivity PEDOT:PSS hydrogel of claim 6, characterized by, It possesses: (1) Conductivity above 10 S / cm; (2) Energy storage modulus above 10 kPa; (3) Cell survival rate of over 90%.

8. A method for preparing the high modulus and high conductivity PEDOT:PSS hydrogel according to any one of claims 1 to 7, characterized in that, Includes the following steps: Preparation of original PEDOT:PSS hydrogel; The original PEDOT:PSS hydrogel was immersed in an acrylic acid aqueous solution for high-frequency liquid exchange more than 3 times. The high-frequency liquid exchange frequency was once every 10-15 minutes with fresh acrylic acid aqueous solution. The PEDOT:PSS hydrogel, after being treated by high-frequency liquid exchange, was immersed in an acrylic acid aqueous solution for low-frequency liquid exchange more than 3 times. The low-frequency liquid exchange frequency was once every 6 to 8 hours with fresh acrylic acid aqueous solution. After the low-frequency solution exchange and soaking process is completed, the hydrogel product is washed with deionized water 5 to 8 times.

9. The application of the high modulus and high conductivity PEDOT:PSS hydrogel according to any one of claims 1 to 7 in flexible electronic devices, wearable sensors, biomedical electrodes, and tissue engineering scaffolds.

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