Conductive organic hydrogel based on pva / pedot:pss, and preparation method and application thereof

Abstract

The application discloses a kind of based on PVA / PEDOT:PSS conductive organic hydrogel and its preparation method and application, belong to conductive organic hydrogel technical field.The hydrogel is prepared using the following method: PEDOT:PSS aqueous dispersion is freeze-dried and dispersed in the mixed solvent of DMSO and deionized water, to obtain mixed solution A;PVA is added to the mixed solvent of DMSO and deionized water, and mixed solution B is obtained by heating under stirring condition in water bath;Mixed solution A and mixed solution B are mixed uniformly, and then further ultrasonic dispersion is carried out, to obtain mixed solution C;Calcium chloride is added to mixed solution C and stirred, to obtain mixed solution D;Mixed solution D is poured into mold and frozen, to obtain anti-freezing PVA / PEDOT:PSS conductive organic hydrogel.The conductive organic hydrogel of the application has excellent conductivity, stretchability and anti-freezing property, and can be applied in low-temperature environment.The preparation method of the application is simple, raw materials are easy to obtain, and the prepared organic hydrogel has good sensing characteristics, and has potential application prospect in the field of flexible wearable devices.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of conductive organic hydrogel, and also relates to biomimetic materials and self-repairing materials, in particular to a conductive organic hydrogel based on PVA / PEDOT:PSS and a preparation method and application thereof. BACKGROUND

[0002] Hydrogels have a broad application prospect in the fields of flexible electronics, biosensors, soft robots, etc. due to their high water content, softness and stretchability, biological tissue-like modulus and multifunctional responsiveness. The common method for preparing conductive hydrogels is to introduce conductive nanofillers into the hydrogel matrix. However, these conductive nanomaterials have poor dispersibility, which leads to discontinuity of the conductive network and incompatibility of the interface. Poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid (PEDOT:PSS) is composed of conductive PEDOT and PSS as a dopant / dispersant. Its core advantage lies in the unique combination of high conductivity, solution processability, flexibility and multifunctionality, which makes it popular in the fields of flexible electronics, biosensors, etc.

[0003] However, pure PEDOT:PSS conductive hydrogels have limitations such as weak mechanical properties, uncontrollable swelling behavior and insufficient biocompatibility. Polyvinyl alcohol (PVA) is an ideal choice for hydrogel matrix materials due to its adjustable cross-linked network, excellent mechanical properties and biocompatibility. In recent years, many PVA / PEDOT:PSS double network conductive hydrogel materials have been developed. For example, Adv. Mater. 2022, 34, 2203650 reports a PEDOT:PSS-PVA hydrogel strain sensor that can continuously monitor physiological signals such as human swallowing and blinking, and detect subtle deformations of human skin to identify gestures. In addition, Adv. Mater. 2023, 35, 2304095 reports a PEDOT:PSS / PVA coating that can introduce a stable conductive polymer hydrogel bioelectronic interface on various device substrate materials (including metals, glass, polymers, etc.), which is used for monitoring various electrophysiological signals in the body and meets the high requirements of clinical bioelectronics for long-term electrochemical stability. However, these PEDOT:PSS / PVA conductive hydrogels still have problems such as poor environmental stability and insufficient low-temperature resistance, which seriously limit their application in winter and even polar environments. SUMMARY

[0004] To solve the above problems, one object of the present application is to provide a PVA / PEDOT:PSS-based conductive organic hydrogel and a preparation method thereof, the present application obtains an organic hydrogel with anti-freezing property by dispersing PVA and PEDOT:PSS in a mixed solvent of dimethyl sulfoxide (DMSO) and water, and further forms an ion crosslinking network by introducing calcium ions, thereby preparing a PVA / PEDOT:PSS conductive organic hydrogel with good mechanical property, anti-freezing property and sensing property.

[0005] To achieve the above object, the specific technical solutions adopted by the present application are as follows:

[0006] A preparation method of a PVA / PEDOT:PSS-based conductive organic hydrogel, comprising the following steps:

[0007] S1, dispersing the PEDOT:PSS aqueous dispersion after freeze-drying in a mixed solvent of DMSO and deionized water to obtain a mixed solution A;

[0008] S2, adding PVA to the mixed solvent of DMSO and deionized water and heating in a water bath under stirring to obtain a mixed solution B;

[0009] S3, uniformly mixing the mixed solution A and the mixed solution B and further ultrasonic dispersing to obtain a mixed solution C;

[0010] S4, adding calcium chloride to the mixed solution C and stirring to obtain a mixed solution D;

[0011] S5, pouring the mixed solution D into a mold and freezing to obtain an anti-freezing PVA / PEDOT:PSS conductive organic hydrogel.

[0012] As a specific embodiment of the present application, in the mixed solvent in steps S1 and S2, the mass ratio of DMSO to deionized water is 1: (0.25-1.5).

[0013] In step S1, the PEDOT:PSS aqueous dispersion is freeze-dried and then dispersed in the mixed solvent, so as to facilitate the control of the ratio of DMSO and water in the mixed solvent, and the specific stirring conditions can be selected as needed, for example, planetary stirring with a rotation speed of 1500-2500 rpm and stirring time of 3-10 min.

[0014] As a specific embodiment of the present application, the mass percentage of PEDOT:PSS in the mixed solution A is 3-7 wt%, and too high concentration will lead to difficulty in uniform dispersion, and too low concentration will lead to significant reduction of the conductive property.

[0015] In step S2, the stirring condition can be selected as required to accelerate the dissolution of PVA, such as stirring at a speed of 100-800 rpm for 1-2 h at a temperature of 95°C.

[0016] In step S3, the ultrasonic treatment is to fully mix the mixed solution A and the mixed solution B, and the specific operation condition can be selected as required, such as ultrasonic dispersion at an ultrasonic power of 600-900 W for 30-60 min.

[0017] As a specific embodiment of the present application, in the mixed solution C, the mass ratio of PEDOT:PSS to PVA is 1: (2.33-9).

[0018] As a specific embodiment of the present application, in the mixed solution D, the concentration of calcium ions is 0.5-3 wt%.

[0019] As a specific embodiment of the present application, in step S5, the freezing temperature is -20 to -25°C, and the freezing time is 1-12 h.

[0020] A conductive organic hydrogel based on PVA / PEDOT:PSS is prepared by the above method.

[0021] Another object of the present application is to provide a method for using the above-mentioned conductive organic hydrogel based on PVA / PEDOT:PSS to prepare a flexible strain sensor and detect strain in a low-temperature environment.

[0022] The principle of the present application is as follows:

[0023] The organic hydrogel of the present application is an organic hydrogel with a multiple network interpenetrating structure. The hydroxyl groups (-OH) and sulfonic acid groups (-SO3 - ) of the PSS segments in PEDOT:PSS form a hydrogen bond network with the hydroxyl groups of PVA, promoting the uniform dispersion of PEDOT nanoparticles in the hydrogel. The synergistic effect of DMSO / calcium ions (Ca 2+ ) can optimize the conductivity, mechanical properties and gelation behavior of the hydrogel material, wherein DMSO mainly regulates the conformation of PEDOT molecules and the gel structure of PVA to improve the conductivity and processability, and inhibits the formation of ice crystals; and Ca 2+ On the one hand, it forms a coordination bond with the hydroxyl groups in PVA to enhance the mechanical strength and stability of the organic hydrogel, and on the other hand, it can interact with the sulfonic acid groups of PSS through electrostatic interaction to improve the dispersion stability of PEDOT:PSS in the composite system.

[0024] Beneficial effects: The conductive organic hydrogel of the present application utilizes DMSO / Ca 2+The synergistic effect of the PVA and the PEDOT:PSS significantly improves the conductivity, tensile strength and anti-freezing performance of the PVA / PEDOT:PSS hydrogel, so that the conductive organic hydrogel has excellent conductivity, tensile property and anti-freezing performance and can be applied to a low-temperature environment.

[0025] The preparation method is simple, raw materials are easy to obtain, and the prepared organic hydrogel has good sensing properties and has potential application prospects in the field of flexible wearable devices. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is a preparation schematic diagram of the PVA / PEDOT:PSS conductive organic hydrogel of the present application;

[0027] Figure 2 It is a physical diagram of the conductive organic hydrogel prepared in Example 1;

[0028] Figure 3 It is a physical diagram of the organic hydrogel prepared in Comparative Example 1 before and after gelation;

[0029] Figure 4 It is an anti-freezing comparison diagram of the organic hydrogels prepared in Example 2 and Comparative Example 2;

[0030] Figure 5 It is a stress-strain curve of the organic hydrogels prepared in Comparative Example 1 and Examples 1-4;

[0031] Figure 6 It is a conductivity comparison diagram of the organic hydrogels prepared in Comparative Example 1 and Examples 1-4;

[0032] Figure 7 It is a signal response curve of each strain sensor in Test Example 3. DETAILED DESCRIPTION

[0033] In order to more clearly illustrate the present application, the present application will be further described below in conjunction with specific examples. Those skilled in the art should understand that the specific description below is illustrative rather than limiting, and should not limit the protection scope of the present application.

[0034] In the following examples and comparative examples, the PVA powder is purchased from Sigma-Aldrich Company, product number 363065, and the molecular weight is 146000-186000; the dried PEDOT:PSS is prepared by the following method: the PEDOT:PSS aqueous dispersion is purchased from Zhuhai Kaixin New Material Technology Co., Ltd., model number KV-ECM-PDD220, and the molecular weight is 70000-90000.

[0035] Example 1: Preparation of anti-freezing PVA / PEDOT:PSS conductive organic hydrogel, the preparation process is as follows:Figure 1 The preparation method comprises the following steps as shown in the figure:

[0036] (1) Pour the PEDOT:PSS aqueous dispersion into a watch glass, and place it in a vacuum freeze dryer for freeze drying. Take 5 g of the dried PEDOT:PSS and add it to 95 g of a mixed solvent (DMSO and deionized water mixed at a mass ratio of 6:4) to obtain dispersion A (5 wt% PEDOT:PSS) by mixing and stirring at a speed of 2000 rpm for 8 min using a planetary mixer;

[0037] (2) Add 5 g of PVA powder to 95 g of the mixed solvent, and stir at a speed of 200 rpm and a temperature of 95°C for 1.5 h to obtain dispersion B (5 wt% PVA);

[0038] (3) Add 1 g of dispersion A and 9 g of dispersion B to a 20 mL beaker, and then place it in an ultrasonic crusher. Ultrasonic power is 800 W, and the ultrasonic time is 45 min to obtain a PVA / PEDOT:PSS dispersion in DMSO / H2O, which is called dispersion C;

[0039] (4) Add 0.05 g of anhydrous calcium chloride to 10 g of dispersion C to obtain a PVA / PEDOT:PSS / Ca 2+ organic hydrogel precursor, which is called mixed solution D;

[0040] (5) Pour the mixed solution D into a polytetrafluoroethylene mold, and place it in a refrigerator at -20°C for 4 h to obtain a freeze-resistant PVA / PEDOT:PSS conductive organic hydrogel.

[0041] The final freeze-resistant PVA / PEDOT:PSS conductive organic hydrogel is shown in Figure 2 .

[0042] Comparative Example 1

[0043] The PVA / PEDOT:PSS organic hydrogel is prepared, and the difference between the preparation steps and those of Example 1 is that the stirring time in step (1) is 5 min, the stirring speed in step (2) is 300 rpm, the stirring time is 1 h, the ultrasonic time in step (3) is 50 min, and the amount of anhydrous calcium chloride in step (4) is 0 g, i.e. no anhydrous calcium chloride is added.

[0044] The prepared PVA / PEDOT:PSS conductive organic hydrogel before and after freezing is shown in Figure 3 After being frozen at -20°C for 4 h, the PVA / PEDOT:PSS changes from a flowing mixed solution to an organic hydrogel state.

[0045] Example 2: Preparation of anti-freezing PVA / PEDOT:PSS conductive organic hydrogel, the difference between the preparation steps and Example 1 is that the stirring time in step (1) is 6 min, the stirring time in step (2) is 1 h, the continuous ultrasonic time in step (3) is 55 min, the amount of anhydrous calcium chloride added in step (4) is 0.1 g, and the freezing time in the refrigerator in step (5) is 8 h.

[0046] Comparative Example 2

[0047] Preparation of PVA / PEDOT:PSS conductive organic hydrogel without DMSO and Ca 2+ , the difference between the preparation steps and Example 2 is that the mixed solvent in steps (1) and (2) is replaced by deionized water, and the amount of anhydrous calcium chloride added in step (4) is 0.

[0048] Preparation of PVA / PEDOT:PSS conductive organic hydrogel without DMSO but with Ca 2+ , the difference between the preparation steps and Example 2 is that the mixed solvent in steps (1) and (2) is replaced by deionized water.

[0049] The morphology of the samples of Comparative Example 2 and Comparative Example 2 before and after freezing treatment at -20°C is shown in Figure 4 , it is found that the sample without DMSO and Ca 2+ has obvious ice formation after freezing; the sample with only Ca 2+ has slightly improved anti-freezing effect, but still freezes; and the sample with both DMSO and Ca 2+ does not freeze and has anti-freezing property.

[0050] Example 3: Preparation of anti-freezing PVA / PEDOT:PSS conductive organic hydrogel, the difference between the preparation steps and Example 1 is that the stirring time in step (1) is 10 min, the stirring time in step (2) is 1 h, the continuous ultrasonic time in step (3) is 60 min, the amount of anhydrous calcium chloride added in step (4) is 0.2 g, and the freezing time in the refrigerator in step (5) is 8 h.

[0051] Example 4: Preparation of anti-freezing PVA / PEDOT:PSS conductive organic hydrogel, the difference between the preparation steps and Example 1 is that the stirring time in step (1) is 5 min, the stirring speed in step (2) is 300 rpm, the stirring time is 1 h, the ultrasonic power in step (3) is 900 W, the continuous ultrasonic time is 50 min, the amount of anhydrous calcium chloride added in step (4) is 0.3 g, and the freezing time in the refrigerator in step (5) is 10 h.

[0052] Test Example 1

[0053] The organic hydrogels of Comparative Example 1 and Examples 1-4 were subjected to mechanical property testing, and tensile testing was performed using a universal testing machine. The test results are shown in Table 1. Figure 5

[0054] Test Example 2

[0055] The organic hydrogels of Comparative Example 1 and Examples 1-4 were subjected to conductivity testing: the mixed solution D in each of the examples and the comparative example was cast into a 1 cm x 1 cm x 1 cm cubic container, and after freezing into a gel at -20°C, a cubic organic hydrogel was obtained. Copper foil was used to connect both ends of the organic hydrogel, and an LCR digital bridge instrument (TH2830) was connected to detect the resistance value, and the conductivity was obtained according to the formula σ = L / RS, where σ is the conductivity, L is the length, R is the detected resistance value, and S is the cross-sectional area. The test results are shown in Table 1. Figure 6

[0056] Table 1 Mechanical properties and conductive properties of each conductive organic hydrogel

[0057]

[0058] Test Example 3

[0059] The conductive organic hydrogels of Examples 1-3 were subjected to sensing testing: two pieces of insulating elastomer (acrylic adhesive tape, model VHB4910 from 3M Company) were used to sandwich the PVA / PEDOT:PSS conductive organic hydrogel to form a sandwich structure, and copper wires were used to connect it and form a strain sensor. The strain sensor was attached to different parts of the human body, and an LCR digital bridge was connected to monitor the relative resistance change signal of the bending of the part in real time.

[0060] The test results are shown in Table 2, where Figure a is the resistance change signal of the index finger bending when the strain sensor prepared using the hydrogel of Example 1 is attached to the index finger joint, Figure b is the resistance change signal of the finger bending when the strain sensor prepared using the hydrogel of Example 2 is attached to the wrist, and Figure c is the resistance change signal of the knee bending when the strain sensor prepared using the hydrogel of Example 3 is attached to the knee. Figure 7

[0061] The above description is merely preferred specific embodiments of the present application, but the scope of protection of the present application is not limited thereto, and any changes or substitutions easily thought of by those skilled in the art within the technical scope disclosed by the present application should be encompassed within the scope of protection of the present application.​​​

Claims

1. A method for preparing a conductive organic hydrogel based on PVA / PEDOT:PSS, characterized in that, Includes the following steps: S1. After freeze-drying the PEDOT:PSS aqueous dispersion, disperse it in a mixed solvent of DMSO and deionized water to obtain mixture A; S2. PVA is added to a mixed solvent of DMSO and deionized water, and heated in a water bath under stirring to obtain mixture B; S3. After mixing the mixture A and the mixture B evenly, further disperse them by ultrasonication to obtain mixture C; S4. Add calcium chloride to the mixture C and stir to obtain mixture D; S5. Pour the mixture D into a mold and freeze it to obtain a freeze-resistant PVA / PEDOT:PSS conductive organic hydrogel.

2. The method for preparing the conductive organic hydrogel based on PVA / PEDOT:PSS according to claim 1, characterized in that, The mass ratio of DMSO to deionized water in the mixed solvent is 1:(0.25~1.5).

3. The method for preparing the conductive organic hydrogel based on PVA / PEDOT:PSS according to claim 1, characterized in that, The mass percentage of PEDOT:PSS in the mixture A is 3~7wt%.

4. The method for preparing the conductive organic hydrogel based on PVA / PEDOT:PSS according to claim 1, characterized in that, The mass ratio of PEDOT:PSS and PVA in the mixture C is 1:(2.33~9).

5. The method for preparing the conductive organic hydrogel based on PVA / PEDOT:PSS according to claim 1, characterized in that, The concentration of calcium ions in the mixture D is 0.5~3wt%.

6. The method for preparing the conductive organic hydrogel based on PVA / PEDOT:PSS according to claim 1, characterized in that, In step S5, the freezing temperature is -20 to -25°C, and the freezing time is 1 to 12 hours.

7. A conductive organic hydrogel based on PVA / PEDOT:PSS, characterized in that, It was prepared using the method described in any one of claims 1-6 for preparing conductive organic hydrogels based on PVA / PEDOT:PSS.

8. An application of a conductive organic hydrogel based on PVA / PEDOT:PSS, characterized in that, The conductive organic hydrogel based on PVA / PEDOT:PSS described in claim 7 was used to prepare a flexible strain sensor and to detect strain in a low-temperature environment.

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