Stimulus-responsive ionic conductive hydrogel as well as preparation method and application thereof

Abstract

The invention discloses stimuli-responsive ionic conductive hydrogel as well as a preparation method and application thereof. The preparation method comprises the steps that a hydrogel precursor solution containing a cross-linking agent, a phase change regulating agent, a photoinitiator, water and PEDOT: PSS is provided, the cross-linking agent comprises laponite, and the phase change regulating agent at least comprises N-isopropylacrylamide; irradiating the hydrogel precursor solution with ultraviolet light, and curing to obtain blocky conductive hydrogel; and fully contacting the blocky conductive hydrogel with a zinc salt solution containing zinc ions to prepare the stimulus-responsive ion conductive hydrogel. The stimulus-responsive ionic conductive hydrogel prepared by the invention can realize good mechanical properties, adhesion performance and conductivity, has sensing performance to strain and temperature, can be prepared into a strain / temperature sensor, and realizes high sensitivity and fast response speed; in addition, a synaptic device can be prepared.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of stimulus-responsive and ion-conductive hydrogels, and specifically relates to a stimulus-responsive ion-conductive hydrogel and a preparation method and application thereof. Background Art

[0002] Hydrogels are elastomers with three-dimensional (3D) network structures. They have attracted much attention in the field of flexible electronics due to their softness, deformability and excellent biocompatibility. Directly combining conductive substances with hydrogels is a convenient and effective method to give hydrogels conductivity. Depending on the conductive substance, conductive hydrogels can be divided into ion conductive hydrogels and electron conductive hydrogels. Ion conductive hydrogels have tissue-like softness (elastic modulus <100 kPa), abundant water content, ionic conductivity and biocompatibility, and have broad application prospects in soft robotics, wearable electronics and bioelectronic engineering. However, disadvantages such as interface mismatch, poor mechanical properties and low sensitivity limit the application of ion conductive hydrogels in real life.

[0003] Biological tissues can respond to different environmental stimuli. For example, mimosa will close when subjected to external mechanical forces (such as touch); chameleons will change their skin color according to the color of the environment; human skin will turn red and produce pain when exposed to heat. Imitating the ability of biological tissues to process and respond to external stimuli is the key to the development of bionic research. Stimuli-responsive hydrogels (smart hydrogels) can not only automatically respond to environmental changes, but also have tissue modulus and biocompatibility comparable to that of organisms. They have broad application prospects in biomedicine, soft robotics, wearable sensing, human-computer interaction, anti-counterfeiting encryption, information transmission and other fields. According to the type of stimulus applied, stimulus-responsive hydrogels can be divided into temperature-responsive hydrogels, humidity-responsive hydrogels, pH-responsive hydrogels, light-responsive hydrogels, ion-responsive hydrogels, magnetic-responsive hydrogels, etc.

[0004] Temperature is the most commonly used stimulus to trigger the responsiveness of hydrogels. According to the response principle and solubility changes, temperature-responsive hydrogels can be divided into hydrogels with lower critical solution temperature (LCST) or higher critical solution temperature (UCST). Common LCST-type temperature-responsive hydrogels include poly (N-isopropylacrylamide), etc. This type of hydrogel is dissolved when the ambient temperature is lower than LCST, and insoluble when it is higher than LCST. Common UCST-type temperature-responsive hydrogels include poly (N-acryloyl glycine), etc. In contrast to the former, this type of hydrogel is insoluble when the ambient temperature is lower than UCST, and is dissolved when it is higher than UCST. However, most temperature-responsive hydrogels have low phase transition temperatures and poor mechanical properties, which limits their application in the field of sensing. Selecting and designing the required hydrogel according to specific application scenarios is a key factor in developing potential applications of stimulus-responsive hydrogels, and it is also the direction that industry researchers have been working on for a long time. Summary of the invention

[0005] The main purpose of the present invention is to provide a stimulus-responsive ion-conductive hydrogel and a preparation method thereof, so as to overcome the deficiencies in the prior art.

[0006] Another object of the present invention is to provide applications of the stimulus-responsive ion-conductive hydrogel.

[0007] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention includes: The embodiment of the present invention provides a method for preparing a stimulus-responsive ion-conductive hydrogel, which comprises: A hydrogel precursor solution comprising a crosslinker, a phase change regulator, a photoinitiator, water and PEDOT:PSS is provided, wherein the crosslinker comprises Laponite XLG, and the chemical structure thereof is as follows: ; The phase change regulator at least includes N-isopropylacrylamide; Irradiating the hydrogel precursor solution with ultraviolet light to solidify it and obtain a block-shaped conductive hydrogel; The block-shaped conductive hydrogel is fully contacted with a zinc salt solution containing zinc ions to prepare a stimulus-responsive ion-conductive hydrogel.

[0008] In some embodiments, the phase change modulator includes a combination of acrylamide and N-isopropylacrylamide.

[0009] An embodiment of the present invention also provides a stimulus-responsive ion-conductive hydrogel prepared by the aforementioned preparation method, wherein the stimulus-responsive ion-conductive hydrogel has an elongation of 1024-1913%, a peel strength on glass of 0.35-47.46 N / m, and has the ability to sense strain and temperature.

[0010] The embodiments of the present invention also provide the use of the aforementioned stimulus-responsive ion-conductive hydrogel in preparing a strain / temperature dual-mode sensor device or a bionic synaptic device.

[0011] Compared with the prior art, the beneficial effects of the present invention are at least: The preparation method provided by the present invention uses aponite XLG as a cross-linking agent, acrylamide and N-isopropylacrylamide as phase change regulators, PEDOT:PSS and zinc sulfate as conductive fillers, and one-pot ultraviolet light induction to prepare a stimulus-responsive ion conductive hydrogel; the preparation method of the present invention is simple and convenient, and the obtained stimulus-responsive ion conductive hydrogel can achieve good mechanical properties and adhesion properties, and at the same time has the perception performance of strain and temperature, and can be prepared into a strain / temperature sensor to achieve high sensitivity and fast response speed; in addition, it can also be prepared into a synaptic device, and a perception synaptic neuromorphic circuit is constructed with a strain / temperature sensor device, which can perceive, distinguish and feedback strain / temperature information in real time. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0013] Figure 1 is a schematic diagram of a preparation process of a stimulus-responsive ion-conductive hydrogel in a typical embodiment of the present invention; Figure 2a and Figure 2b is a scanning electron microscope photo and an enlarged photo of the stimulus-responsive ion-conductive hydrogel prepared in Example 1 of the present invention; Figure 3a is a stress-strain curve diagram of the stimulus-responsive ion-conductive hydrogel prepared in Example 1 of the present invention; Figure 3b is a peel strength curve of the stimulus-responsive ion-conductive hydrogel prepared in Example 1 of the present invention; Figure 4 is an electrochemical impedance spectrum of the stimulus-responsive ion-conductive hydrogel prepared in Example 1 of the present invention; Figure 5a is a curve diagram showing the change in relative resistance rate of the stress sensor device based on the stimulus-responsive ion-conductive hydrogel as a function of strain in Example 1 of the present invention; Figure 5bIt is a schematic diagram of the response speed results of the stress sensor device based on the stimulus-responsive ion-conductive hydrogel in Example 1 of the present invention; Figure 6a is a curve diagram showing the change in relative resistance rate of the temperature sensor device based on the stimulus-responsive ion-conductive hydrogel as a function of temperature in Example 1 of the present invention; Figure 6b It is a schematic diagram of the response speed results of the temperature sensor device based on the stimulus-responsive ion conductive hydrogel in Example 1 of the present invention; Figure 7 It is a schematic diagram of the results of integrating the sensor element based on the stimulus-responsive ion-conductive hydrogel and the synaptic device in Example 1 of the present invention, and performing sensing processing-feedback under temperature (35°C, 45°C, 55°C) and stress (200%, 500%, 1000%) stimulation. DETAILED DESCRIPTION

[0014] In view of the defects of the prior art, the technical solution proposed in the present invention is mainly to provide a stimulus-responsive ion-conductive hydrogel with good mechanical properties and adhesion properties and the ability to sense strain and temperature. Furthermore, it can also be combined with synaptic devices to construct a perceptual synaptic morphology circuit to simulate the "perception-feedback" neural circuit of the organism.

[0015] The technical solution, its implementation process and principle are further explained below. However, it should be understood that within the scope of the present invention, the above-mentioned technical features of the present invention and the technical features specifically described in the following (embodiments) can be combined with each other to form a new or preferred technical solution. Due to space limitations, they will not be described one by one here.

[0016] As one aspect of the technical solution of the present invention, it involves a stimulus-responsive ion-conductive hydrogel, which is prepared by a one-pot ultraviolet light induction method using Laponite XLG as a cross-linking agent, at least N-isopropylacrylamide as a phase change regulator, PEDOT:PSS and zinc sulfate as conductive fillers.

[0017] In some specific embodiments, the method for preparing the stimulus-responsive ion-conductive hydrogel comprises: Providing a hydrogel precursor solution comprising a crosslinker, a phase change regulator, a photoinitiator, water and PEDOT:PSS, wherein the crosslinker comprises Laponite XLG, and the phase change regulator preferably comprises a combination of acrylamide and N-isopropylacrylamide; Irradiating the hydrogel precursor solution with ultraviolet light to solidify it and obtain a block-shaped conductive hydrogel; The block-shaped conductive hydrogel is fully contacted with a zinc salt solution containing zinc ions to prepare a stimulus-responsive ion-conductive hydrogel.

[0018] The preparation mechanism of the present invention is: the phase transition temperature of the hydrogel is regulated by adjusting the ratio of acrylamide to N-isopropylacrylamide, and Laponite XLG is used as a cross-linking agent to give the hydrogel excellent mechanical properties, adhesion properties and self-healing properties. Since acrylamide has an active -NH2 group, when the acrylamide content increases, the hydrogen bonding between the polymer chain and the water molecules is strengthened, resulting in an increase in the phase transition temperature of the hydrogel. The increase in the content of active amino groups in acrylamide also leads to the enhancement of electrostatic and hydrogen bonding in the polymer chain, which is manifested in the macroscopic improvement of the mechanical properties and adhesion properties of the hydrogel, and is superior to most stimulus-responsive ion-conductive hydrogels.

[0019] In addition, the introduced conductive components (PEDOT:PSS, zinc salt) have a synergistic effect. When zinc salt is transported as a conductive ion, it can interact with PEDOT and PSS of PEDOT:PSS, reducing the Coulomb interaction between the polymer chains of PEDOT:PSS, thereby improving the ionic conductivity of the hydrogel and improving its mechanical properties. At the same time, PEDOT:PSS has inherent ionic / electronic conductivity and abundant sulfonic acid groups, which can accelerate the Zn 2+ The transmission of the hydrogel sensor improves its sensitivity. Therefore, by regulating the conductive components, the ion conductive hydrogel can achieve highly sensitive strain / temperature information perception, and a strain / temperature sensor with high sensitivity and fast response speed can be prepared. Furthermore, a bionic synaptic device based on the stimulus-responsive ion conductive hydrogel can also be prepared, which has the basic properties of a synapse and low energy consumption, and is combined with a strain / temperature sensing device to construct a sensing synaptic neuromorphic circuit, which can sense, distinguish and feedback strain / temperature information in real time.

[0020] In some embodiments, the preparation method specifically includes: mixing a crosslinker, a phase change regulator, a photoinitiator, and water, and magnetically stirring in an ice water bath, and then adding PEDOT:PSS and stirring evenly to obtain the hydrogel precursor solution.

[0021] In some more specific embodiments, the mass ratio of N-isopropylacrylamide, photoinitiator, acrylamide, and PEDOT:PSS in the hydrogel precursor solution is 100:1.2:0~25:5~20.

[0022] In some more specific embodiments, the concentration of Laponite XLG in the hydrogel precursor solution is 25-45 mmol / L.

[0023] Further, the photoinitiator may include I2959 photoinitiator, but is not limited thereto.

[0024] In some embodiments, the preparation method specifically includes: placing the hydrogel precursor solution in a mold, sealing it, and curing it by ultraviolet light in an ice water bath at 0-5°C.

[0025] In some embodiments, the irradiation time is 15 to 25 minutes, and the wavelength of the ultraviolet light used is 365 nm.

[0026] In some embodiments, the preparation method specifically includes: immersing the block-shaped conductive hydrogel in a zinc salt solution containing zinc ions to obtain a stimulus-responsive ion-conductive hydrogel.

[0027] Furthermore, the immersion time is 1 s to 2 h.

[0028] In some embodiments, the concentration of zinc ions in the zinc salt solution is 0.01-0.5 mol / L.

[0029] In some embodiments, the zinc salt solution includes, but is not limited to, a zinc sulfate solution.

[0030] Among them, for some more specific implementation plans, please refer to Figure 1 As shown, the method for preparing the stimulus-responsive ion-conductive hydrogel comprises the following steps: (1) Prepare hydrogel precursor solution: Add N-isopropylacrylamide, I2959 photoinitiator, acrylamide and Laponite XLG to deionized water and stir magnetically in an ice water bath at 800 rpm until the solution is clear. Then add PEDOT:PSS solution with a pipette and continue stirring until the solution is homogeneous. (2) Preparation of bulk conductive hydrogel: Pour the prepared hydrogel precursor solution into the mold, remove the bubbles, and seal the mold with a transparent PET cap. After irradiation with 365 nm ultraviolet light for 15-25 minutes in an ice water bath, a solidified bulk conductive hydrogel is obtained; (3) Preparation of stimulus-responsive ion-conductive hydrogel: Immerse the obtained block-shaped conductive hydrogel in a zinc sulfate solution and store it in a refrigerator for later use.

[0031] Wherein, in step (1), the volume of deionized water is 10 mL.

[0032] Furthermore, in step (2), the size of the mold is (10×30×1) mm 3 .

[0033] In some preferred embodiments, in step (3), the concentration of the zinc sulfate solution is 0.01-0.5 mol / L, and the immersion time ranges from 1 s to 2 h.

[0034] Another aspect of the present invention provides a stimulus-responsive ion-conductive hydrogel prepared by the above-mentioned preparation method. The stimulus-responsive ion-conductive hydrogel has an elongation of 1024-1913%, a peel strength to glass of 0.35-47.46 N / m, and has the ability to sense strain and temperature.

[0035] Furthermore, the preparation method of the present invention is simple and convenient, and the obtained hydrogel can achieve good mechanical properties (such as good tensile properties), adhesion properties and conductive properties, and at the same time has the ability to sense strain and temperature, can respond to stress and temperature stimuli at the same time, and can be prepared into a strain / temperature sensor to achieve high sensitivity and fast response speed; in addition, it can also be prepared into a synaptic device, and a perceptual synaptic neuromorphic circuit is constructed with a strain / temperature sensor device, which can sense, distinguish and feedback strain / temperature information in real time, thereby realizing the application of wearable sensing and perceptual synapses.

[0036] Another aspect of the embodiments of the present invention further provides the use of the aforementioned stimulus-responsive ion-conductive hydrogel in preparing a strain / temperature dual-mode sensor device or a bionic synaptic device.

[0037] Through the above technical scheme, the various components of the present invention endow the stimulus-responsive conductive hydrogel with excellent mechanical properties and adhesion properties; the stimulus-responsive conductive hydrogel has strain and temperature perception, can be prepared into strain / temperature sensors and bionic synapses, and can construct perceptual synaptic neuromorphic circuits, which can perceive, distinguish and feedback strain / temperature information in real time, forming a neural circuit that simulates the "perception-feedback" of an organism.

[0038] In order to make the purpose, technical solution and application of the present invention clearer, the technical solution of the present invention is further described in detail below in conjunction with several preferred embodiments and drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention. The implementation conditions used in the following embodiments can be further adjusted according to actual needs, and the unspecified implementation conditions are usually the conditions in conventional experiments.

[0039] Example 1 This embodiment provides a method for preparing a stimulus-responsive ion-conductive hydrogel, and the specific steps include: (1) Prepare hydrogel precursor solution: Add 1.13 g N-isopropylacrylamide, 0.014 g I2959 photoinitiator, 0.226 g acrylamide and 40 mmol / L Laponite XLG to 10 mL deionized water and stir magnetically in an ice water bath at 800 rpm until the solution is clear. Then add 0.113 g PEDOT:PSS solution with a pipette and continue stirring until the solution is homogeneous. (2) Preparation of bulk conductive hydrogel: Pour the prepared hydrogel precursor solution into the mold, remove the bubbles, and seal the mold with a transparent PET cap. After irradiation with 365 nm ultraviolet light for 20 minutes in an ice water bath, a solidified bulk conductive hydrogel is obtained; (3) Preparation of stimulus-responsive ion-conductive hydrogel: The obtained block-shaped conductive hydrogel was immersed in a 0.1 mol / L zinc sulfate solution for 30 s. After immersion, the PNXAS-ZnSO4 hydrogel was obtained and stored in a refrigerator for later use.

[0040] The inventors of this case also characterized and analyzed the stimulus-responsive ion-conductive hydrogel prepared in this embodiment, and the results are as follows: Figure 2a and Figure 2b is a scanning electron microscope photo and a magnified photo of the stimulus-responsive ion-conductive hydrogel; Figure 2a and Figure 2b It can be seen that the hydrogel surface is evenly distributed with pores and the average pore size is 4.54 ± 0.07 μm.

[0041] Figure 3a The stress-strain curve of the stimulus-responsive ion-conductive hydrogel is shown in Figure 2. Its elongation is 1913%, the corresponding Young's modulus is 48.463 kPa, and the toughness is 0.878 MJ / m 3 , the maximum tensile strength is 80.69 kPa. Figure 3b FIG. 5 is a peel strength curve of the stimuli-responsive ion-conductive hydrogel, and its peel strength with respect to glass is 46.35 kPa.

[0042] Figure 4 This is the electrochemical impedance spectrum of the stimulus-responsive ion-conductive hydrogel, and its ionic conductivity can be calculated to be 6.37 mS / cm.

[0043] Figure 5a and Figure 5b They are the sensitivity and response speed of the stress sensor device based on the stimulus-responsive ion-conductive hydrogel, respectively. Its gauge factor GF can reach up to 7.94, and the response speed is 87 ms.

[0044] Figure 6a and Figure 6bThey are the sensitivity and response speed of the temperature sensor device based on the stimulus-responsive ion-conductive hydrogel, respectively. Its temperature coefficient of resistance TCR can reach up to -1.974% / °C, and the response speed is 270 ms.

[0045] The bionic synaptic device based on the stimulus-responsive ion-conductive hydrogel obtained in this embodiment is combined with the corresponding sensor element to form an artificial neural sensory system, see Figure 7 , it can sense temperature and stress while transmitting synaptic signals, and can be used in multimodal artificial sensory transmission neural systems.

[0046] Example 2 This embodiment provides a method for preparing a stimulus-responsive ion-conductive hydrogel, and the specific steps include: (1) Prepare hydrogel precursor solution: Add 1.13 g N-isopropylacrylamide, 0.014 g I2959 photoinitiator, 0.013 g acrylamide and 40 mmol / L Laponite XLG to 10 mL deionized water and stir magnetically in an ice water bath at 800 rpm until the solution is clear. Then add 0.113 g PEDOT:PSS solution with a pipette and continue stirring until the solution is homogeneous. (2) Preparation of bulk conductive hydrogel: Pour the prepared hydrogel precursor solution into the mold, remove the bubbles, and seal the mold with a transparent PET cap. After irradiation with 365 nm ultraviolet light for 20 minutes in an ice water bath, a solidified bulk conductive hydrogel is obtained; (3) Preparation of stimulus-responsive ion-conductive hydrogel: The obtained block-shaped conductive hydrogel was immersed in a 0.1 mol / L zinc sulfate solution for 30 s. After immersion, the PNXAS-ZnSO4 hydrogel was obtained and stored in a refrigerator for later use.

[0047] The sample was subjected to mechanical property testing, and the results showed that the stress-strain curve of the stimulus-responsive ion-conductive hydrogel showed an elongation of 1080%, a corresponding Young's modulus of 10.63 kPa, and a toughness of 0.347 MJ / m 3 , the maximum tensile strength is 40.28 kPa.

[0048] Example 3 This embodiment provides a method for preparing a stimulus-responsive ion-conductive hydrogel, and the specific steps include: (1) Prepare hydrogel precursor solution: Add 1.13 g N-isopropylacrylamide, 0.014 g I2959 photoinitiator, 0.226 g acrylamide and 0.31 g Laponite XLG to 10 mL deionized water and stir magnetically in an ice water bath at 800 rpm until the solution is clear. Then add 0.226 g PEDOT:PSS solution with a pipette and continue stirring until the solution is homogeneous. (2) Preparation of bulk conductive hydrogel: Pour the prepared hydrogel precursor solution into the mold, remove the bubbles, and seal the mold with a transparent PET cap. After irradiation with 365 nm ultraviolet light for 20 minutes in an ice water bath, a solidified bulk conductive hydrogel is obtained; (3) Preparation of stimulus-responsive ion-conductive hydrogel: Immerse the obtained block-shaped conductive hydrogel in 0.1 mol / L zinc sulfate solution for 30 s and store it in a refrigerator for later use.

[0049] The mechanical properties of the sample were tested, and the results showed that the stress-strain curve of the stimulus-responsive ion-conductive hydrogel showed an elongation of 1024%, a corresponding Young's modulus of 53.08 kPa, and a toughness of 0.24 MJ / m 3 , the maximum tensile strength is 44.28 kPa.

[0050] Example 4 This embodiment provides a method for preparing a stimulus-responsive ion-conductive hydrogel, and the specific steps include: (1) Prepare hydrogel precursor solution: Add 1.13 g N-isopropylacrylamide, 0.014 g I2959 photoinitiator, 0.226 g acrylamide and 40 mmol / L Laponite XLG to 10 mL deionized water and stir magnetically in an ice water bath at 800 rpm until the solution is clear. Then add 0.113 g PEDOT:PSS solution with a pipette and continue stirring until the solution is homogeneous. (2) Preparation of bulk conductive hydrogel: Pour the prepared hydrogel precursor solution into the mold, remove the bubbles, and seal the mold with a transparent PET cap. After irradiation with 365 nm ultraviolet light for 20 minutes in an ice water bath, a solidified bulk conductive hydrogel is obtained; (3) Preparation of stimulus-responsive ion-conductive hydrogel: The obtained block-shaped conductive hydrogel was immersed in a 0.1 mol / L zinc sulfate solution for 2 h. After immersion, it was stored in a refrigerator for later use.

[0051] The sample was tested for electrochemical impedance spectroscopy, and its ionic conductivity was calculated to be 23.68 mS / cm. Its adhesion performance was tested, and its adhesion strength to glass was found to be 0.35 N / m.

[0052] Example 5 This embodiment provides a method for preparing a stimulus-responsive ion-conductive hydrogel, and the specific steps include: (1) Prepare hydrogel precursor solution: Add 1.13 g N-isopropylacrylamide, 0.014 g I2959 photoinitiator, 0.226 g acrylamide and 40 mmol / L Laponite XLG to 10 mL deionized water and stir magnetically in an ice water bath at 800 rpm until the solution is clear. Then add 0.113 g PEDOT:PSS solution with a pipette and continue stirring until the solution is homogeneous. (2) Preparation of bulk conductive hydrogel: Pour the prepared hydrogel precursor solution into the mold, remove the bubbles, and seal the mold with a transparent PET cap. After irradiation with 365 nm ultraviolet light for 20 minutes in an ice water bath, a solidified bulk conductive hydrogel is obtained; (3) Preparation of stimulus-responsive ion-conductive hydrogel: Immerse the obtained block-shaped conductive hydrogel in 0.1 mol / L zinc sulfate solution for 1 s and store it in a refrigerator for later use.

[0053] The sample was tested for electrochemical impedance spectroscopy, and its ionic conductivity was calculated to be 2.278 mS / cm. Its adhesion performance was tested, and its adhesion strength to glass was found to be 47.46 N / m.

[0054] Example 6 This embodiment provides a method for preparing a stimulus-responsive ion-conductive hydrogel, and the specific steps include: (1) Prepare hydrogel precursor solution: Add 1.13 g N-isopropylacrylamide, 0.014 g I2959 photoinitiator, 0.226 g acrylamide and 40 mmol / L Laponite XLG to 10 mL deionized water and stir magnetically in an ice water bath at 800 rpm until the solution is clear. Then add 0.113 g PEDOT:PSS solution with a pipette and continue stirring until the solution is homogeneous. (2) Preparation of bulk conductive hydrogel: Pour the prepared hydrogel precursor solution into the mold, remove the bubbles, and seal the mold with a transparent PET cap. After irradiation with 365 nm ultraviolet light for 20 minutes in an ice water bath, a solidified bulk conductive hydrogel is obtained; (3) Preparation of stimulus-responsive ion-conductive hydrogel: Immerse the obtained block-shaped conductive hydrogel in 0.5 mol / L zinc sulfate solution for 30 s and store it in a refrigerator for later use.

[0055] The sample was tested for electrochemical impedance spectroscopy, and its ionic conductivity was calculated to be 9.34 mS / cm. Its adhesion performance was tested, and its adhesion strength to glass was found to be 36 N / m.

[0056] Example 7 This embodiment provides a method for preparing a stimulus-responsive ion-conductive hydrogel, and the specific steps include: (1) Prepare hydrogel precursor solution: Add 1.13 g N-isopropylacrylamide, 0.014 g I2959 photoinitiator and 40 mmol / L Laponite XLG to 10 mL deionized water and stir magnetically in an ice water bath at 800 rpm until the solution is clear. Then add 0.113 g PEDOT:PSS solution with a pipette and continue stirring until the solution is homogeneous. (2) Preparation of bulk conductive hydrogel: Pour the prepared hydrogel precursor solution into the mold, remove the bubbles, and seal the mold with a transparent PET cap. After irradiation with 365 nm ultraviolet light for 20 minutes in an ice water bath, a solidified bulk conductive hydrogel is obtained; (3) Preparation of stimulus-responsive ion-conductive hydrogel: Immerse the obtained block-shaped conductive hydrogel in 0.01 mol / L zinc sulfate solution for 30 s and store it in a refrigerator for later use.

[0057] After testing, the sensitivity and response speed of the temperature sensor device of the conductive hydrogel of this embodiment are slightly worse than those of embodiment 1.

[0058] Comparative Example 1 This comparative example is different from Example 1 in that: N, N' - Methylene bisacrylamide as a crosslinker, i.e. replacing Laponite XLG with N,N' - Methylene bisacrylamide.

[0059] The final hydrogel has poor mechanical and adhesive properties, with a maximum elongation of 200% and a maximum peel strength of only 5 N / m on glass, which is much lower than the hydrogel prepared with Laponite XLG as the crosslinker. This shows that the presence of Laponite XLG greatly improves the mechanical and adhesive properties of the hydrogel.

[0060] Comparative Example 2 The difference between this comparative example and Example 1 is that the prepared hydrogel is not immersed in a zinc sulfate solution, that is, the stimulus-responsive ion-conductive hydrogel obtained by the above technical solution does not contain zinc sulfate.

[0061] The response speed of the strain sensor device is 260 ms, and the response speed of the temperature sensor device is 323 ms, which is slower than that of the hydrogel after being soaked in zinc sulfate. This indicates that the addition of zinc sulfate increases the amount of conductive substances inside the hydrogel, improving the response speed of the hydrogel strain and temperature sensing.

[0062] Comparative Example 3 The difference between this comparative example and Example 1 is that: N-isopropylacrylamide is not included, that is, there is no N-isopropylacrylamide monomer in the prepared hydrogel.

[0063] The final temperature sensor device has poor sensing performance, with a maximum temperature coefficient of resistance TCR1 of -1.949% / °C and TCR2 of -0.625% / °C, and only two stages without a phase change stage, indicating that the hydrogel containing N-isopropylacrylamide monomer has a higher sensitivity to temperature sensing. Since PNXAS-ZnSO4 hydrogel has a phase change stage during the heating process, the NIPAM chain agglomerates due to hydrophobicity during the phase change and excludes water from the polymer chain, the probability of PEDOT:PSS chains dispersed in the aqueous solution contacting each other increases, and the movement of positive and negative ions of zinc sulfate is less hindered by the original polymer chain, and the movement speed is accelerated. Therefore, the presence of NIPAM monomer is of great significance for improving the sensitivity of PNXAS-ZnSO4 hydrogel to temperature.

[0064] Comparative Example 4 The difference between this comparative example and Example 1 is that PEDOT:PSS is not included.

[0065] The mechanical properties and adhesion strength of the hydrogel obtained in the end are both reduced, with a maximum elongation of 1520% and an adhesion strength of 23.48 N / m to glass, which is due to the reduction of hydrogen bonding in the system. The response speed of the strain sensor device obtained in the end is 960 ms, and the response speed of the temperature sensor device obtained in the end is 758 ms. In addition, the sensing performance of the temperature sensor device obtained in the end is poor, with a maximum resistance temperature coefficient TCR1 of -1.36% / °C. This is because the only conductive substance in the system is zinc sulfate ions, so the sensing performance is reduced.

[0066] In addition, the inventors of this case also referred to the aforementioned embodiments and conducted experiments with other raw materials, process operations, and process conditions described in this specification, and obtained relatively ideal results.

[0067] It should be understood that the above examples are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a stimulus-responsive ion-conductive hydrogel, characterized in that: include: Providing a hydrogel precursor solution comprising a crosslinker, a phase change regulator, a photoinitiator, water and PEDOT:PSS, wherein the crosslinker comprises lithium terephthalate; The phase change regulator at least includes N-isopropylacrylamide; Irradiating the hydrogel precursor solution with ultraviolet light to solidify it and obtain a block-shaped conductive hydrogel; The block-shaped conductive hydrogel is fully contacted with a zinc salt solution containing zinc ions to prepare a stimulus-responsive ion-conductive hydrogel.

2. The preparation method according to claim 1, characterized in that: include: The crosslinking agent, the phase change regulator, the photoinitiator and water are mixed and magnetically stirred in an ice water bath, and then PEDOT:PSS is added and stirred evenly to obtain the hydrogel precursor solution; And / or, the phase change regulator includes a combination of acrylamide and N-isopropylacrylamide.

3. The preparation method according to claim 2, characterized in that: The mass ratio of N-isopropylacrylamide, photoinitiator, acrylamide, and PEDOT:PSS in the hydrogel precursor solution is 100:1.2:0-25:5-20.

4. The preparation method according to claim 1 or 2, characterized in that: The concentration of lithium terephthalate in the hydrogel precursor solution is 25-45 mmol / L; and / or, the photoinitiator includes I2959 photoinitiator.

5. The preparation method according to claim 1 or 2, characterized in that: include: The hydrogel precursor solution is placed in a mold, sealed, and cured by ultraviolet light in an ice water bath at 0-5°C.

6. The preparation method according to claim 1, characterized in that: The irradiation time is 15-25 minutes; the wavelength of the ultraviolet light used is 365 nm.

7. The preparation method according to claim 1, characterized in that include: The block-shaped conductive hydrogel is immersed in a zinc salt solution containing zinc ions to obtain a stimulus-responsive ion-conductive hydrogel; preferably, the immersion time is 1 s to 2 h.

8. The preparation method according to claim 1, characterized in that: The concentration of zinc ions in the zinc salt solution is 0.01-0.5 mol / L; and / or the zinc salt solution comprises a zinc sulfate solution.

9. A stimulus-responsive ion-conductive hydrogel prepared by the preparation method according to any one of claims 1 to 8, wherein the stimulus-responsive ion-conductive hydrogel has an elongation of 1024-1913%, a peel strength to glass of 0.35-47.46 N / m, and has the ability to sense strain and temperature.

10. Use of the stimulus-responsive ion-conductive hydrogel according to claim 9 in preparing strain / temperature dual-mode sensor devices or bionic synaptic devices.

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