Preparation method and application of a multifunctional flexible conductive organic hydrogel

Abstract

This invention discloses a method for preparing and applying a multifunctional flexible conductive organic hydrogel. The invention uses chitosan, acrylic acid, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide, 2-methoxyethyl acrylate, LiCl, and dimethyl sulfoxide as materials. The dual-network system of CS and P (AA-co-SBMA-co-MEA) compensates for the poor mechanical properties of single-network hydrogels. AA and SBMA impart adhesiveness to the hydrogel, and the addition of LiCl and DMSO improves its conductivity and antifreeze / moisturizing properties. The multifunctional flexible conductive organic hydrogel of this invention exhibits good adhesion and antifreeze / moisturizing properties. The preparation method is simple and convenient. The prepared composite hydrogel has various interesting sensing applications and can be assembled with Ecoflex films to form triboelectric nanogenerators and capacitive non-contact sensors.

Description

Technical Field

[0001] This invention relates to a method for preparing and applying a conductive organic hydrogel, and more particularly to a method for preparing and applying a multifunctional flexible conductive organic hydrogel. Background Technology

[0002] With the advancement of technology, people's demands for electronic products are increasing, especially for electronic devices with excellent conductivity and flexibility, which play an important role in realizing human-computer interaction and soft robotics. However, conductive hydrogel sensors still have problems in practical applications. For example, reduced sensitivity, unstable signal transmission, extremely narrow application range, and lack of portability. Therefore, the preparation of composite hydrogels with excellent performance and multifunctional applications has become the current development trend.

[0003] Meanwhile, with the increasing prevalence of wearable sensors, their portability, intelligence, and durability have garnered significant attention. Triboelectric nanogenerators (TENGs), capable of both real-time sensing and energy harvesting for multi-functional device applications, have thus gained popularity. Non-contact flexible devices have become the preferred choice for IoT technology applications. These devices enable gesture recognition without physical contact, preventing the spread of viruses and even meeting sensing and detection needs in special circumstances such as dark environments. Therefore, flexible electronic devices with integrated multiple functions will play a crucial role in the next generation of intelligent sensing. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing a multifunctional flexible conductive organic hydrogel. The preparation method is simple and easy to operate. The prepared composite hydrogel has good adhesion, antifreeze and moisturizing properties, and a variety of interesting sensing applications.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is to provide a method for preparing a multifunctional flexible conductive organic hydrogel, comprising the following steps: S1) dissolving chitosan in acidic deionized water and stirring at room temperature to obtain a homogeneous solution; S2) adding acrylic acid, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide and LiCl to the above solution and continuing to stir at room temperature; dissolving 2-methoxyethyl acrylate in dimethyl sulfoxide, mixing it evenly and then adding it to the above mixed solution; S3) continuing to add photoinitiator 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylacetophenone and crosslinking agent N,N-methylenebisacrylamide to the above mixed solution and stirring magnetically; S4) degassing the mixed solution obtained in step S3 under vacuum and photopolymerizing it by ultraviolet irradiation to obtain a multifunctional flexible conductive organic hydrogel.

[0006] Furthermore, the deionized water in step S1 contains 2% acetic acid, the chitosan has a mass fraction of 2%-5%, and the stirring time is 2h-5h.

[0007] Further, the mass ratio of acrylic acid to chitosan is 8:1-15:1; the mass ratio of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide to chitosan is 3:1-6:1; the mass ratio of LiCl to chitosan is 1:1-3:1; the mass ratio of 2-methoxyethyl acrylate to [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide is 1:1-2:1; and the ratio of dimethyl sulfoxide to deionized water is 1:2-2:1.

[0008] Furthermore, the photoinitiator 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylacetophenone has a mass of 1-5 wt% of acrylic acid, and the crosslinking agent N,N-methylenebisacrylamide has a mass of 0.3-1.5% of acrylic acid.

[0009] Furthermore, the ultraviolet light irradiation time in step S5 is 15-45 minutes.

[0010] Furthermore, the stirring time in step S2 is 30 min-120 min, the stirring time in step S3 is 1 h-3 h, and the photopolymerization in step S4 is carried out by ultraviolet irradiation under inert gas or nitrogen protection.

[0011] Another object of the present invention is to provide a multifunctional flexible conductive organic hydrogel, which is prepared by the above-described preparation method.

[0012] A third objective of this invention is to provide applications of the aforementioned multifunctional flexible conductive organic hydrogel in artificial intelligence and flexible electronics technology. These include:

[0013] A triboelectric nanogenerator is provided, which is assembled from the hydrogel obtained in step S4 above and the Ecoflex film in a sandwich structure.

[0014] A capacitive non-contact sensor is provided, which is obtained by stacking the hydrogel obtained in step S4 above with an Ecoflex film in a layer-by-layer manner; the number of stacked layers is 3 or 4.

[0015] Furthermore, the Ecoflex film is formed by uniformly mixing Ecoflex components A and B in a 1:1 ratio and placing it at a high temperature for 20-60 minutes.

[0016] Compared with existing technologies, this invention offers the following advantages: The preparation method and application of the multifunctional flexible conductive organic hydrogel provided by this invention are simple and convenient; the prepared composite hydrogel exhibits good adhesion and antifreeze / moisturizing properties, satisfying various interesting sensing applications, and can be assembled with Ecoflex films to form triboelectric nanogenerators (TENGs) or capacitive non-contact sensors. Specific advantages are as follows:

[0017] 1. The flexible conductive adhesive antifreeze hydrogel of this invention is a dual-network system, which overcomes the shortcomings of single-network hydrogels and maintains good mechanical properties even after repeated use. Furthermore, by incorporating the natural material CS into the hydrogel and utilizing ions for conductivity, the prepared dual-network hydrogel integrates flexibility, adhesion, antifreeze and moisturizing properties, and conductivity. It can monitor various human movements in real time and has broad application prospects in flexible wearable devices, intelligent artificial skin, and other fields.

[0018] 2. The TENG assembled from the multifunctional flexible conductive organic hydrogel and Ecoflex film of the present invention can sensitively convert mechanical energy into electrical energy and output different electrical signals according to different applied forces, thus realizing adjustable voltage signals.

[0019] 3. The multifunctional flexible conductive organic hydrogel of the present invention can be assembled with Ecoflex film to form a capacitive non-contact sensor, which has stable and sensitive sensing ability and can distinguish the distance between a finger and the sensor. Attached Figure Description

[0020] Figure 1 A schematic diagram showing the sensing performance of the hydrogel sensor prepared according to the present invention for human motion is displayed.

[0021] Figure 2 The invention demonstrates that the TENG assembled with the hydrogel and Ecoflex film prepared in this invention can collect external mechanical energy and convert it into electrical energy.

[0022] Figure 3 This demonstrates that the capacitive non-contact sensor assembled with the hydrogel and Ecoflex film prepared according to the present invention can identify the distance between a finger and the sensor based on changes in capacitance. The sensing sensitivity of the non-contact sensor is also demonstrated. Detailed Implementation

[0023] The present invention will now be further described with reference to the accompanying drawings and embodiments.

[0024] This invention utilizes chitosan (CS), acrylic acid (AA), [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SBMA), 2-methoxyethyl acrylate (MEA), LiCl, and dimethyl sulfoxide (DMSO) as materials, significantly enriching the various properties of the composite hydrogel. During the preparation process, CS and P(AA-co-SBMA-co-MEA) form a double-network structure, compensating for the poor mechanical properties of single-network hydrogels and improving their mechanical properties. Simultaneously, the addition of AA and zwitterionic SBMA improves the hydrogel's adhesion, while the presence of DMSO and LiCl endows the hydrogel with excellent water retention, antifreeze properties, and ionic conductivity.

[0025] The preparation method of the multifunctional flexible conductive organic hydrogel of the present invention includes the following steps:

[0026] S1) Chitosan is dissolved in acidic deionized water and stirred at room temperature to obtain a homogeneous solution; the deionized water contains 2% acetic acid, the mass fraction of chitosan is 2%-5%, and the stirring time is 2h-5h. If the mass fraction of chitosan is less than 2%, the mechanical properties of the resulting hydrogel are very poor; if it is greater than 5%, a homogeneous solution cannot be obtained, and undissolved chitosan will still exist.

[0027] S2) Add acrylic acid, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide, and LiCl to the above solution and continue stirring at room temperature for 30-120 minutes. Dissolve 2-methoxyethyl acrylate in dimethyl sulfoxide, mix thoroughly, and then add it to the above mixed solution. The mass ratio of acrylic acid to chitosan is 8:1-15:1. If the mass ratio of acrylic acid to chitosan is less than 8:1, the resulting gel is too soft and has poor mechanical strength; if it is greater than 15:1, the resulting hydrogel is too brittle and has poor tensile properties. The mass ratio of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide to chitosan is 3:1-6:1; the mass ratio of LiCl to chitosan is 1:1-3:1; the mass ratio of 2-methoxyethyl acrylate to [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide is 1:1-2:1; and the ratio of dimethyl sulfoxide to deionized water is 1:2-2:1.

[0028] S3) Continue to add the photoinitiator 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylacetophenone and the crosslinking agent N,N-methylenebisacrylamide to the above mixed solution, and stir magnetically for 1-3 hours. The mass of the photoinitiator 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylacetophenone is 1-5 wt% of acrylic acid, and the mass of the crosslinking agent N,N-methylenebisacrylamide is 0.3-1.5% of acrylic acid. If the amount of photoinitiator and crosslinking agent added is lower than the minimum value, gelation will not occur; if it is higher than the maximum value, the degree of crosslinking of the gel will be too high, and the mechanical tensile strain will be low.

[0029] S4) The mixed solution obtained in step S3 is degassed under vacuum and photopolymerized by ultraviolet irradiation to obtain a multifunctional flexible conductive organic hydrogel.

[0030] The present invention relates to the application of the above-mentioned multifunctional flexible conductive organic hydrogel in artificial intelligence and flexible electronics technology. This includes:

[0031] A triboelectric nanogenerator is provided, which uses the hydrogel obtained in the above steps to form a sandwich structure of Ecoflex film + hydrogel + Ecoflex film.

[0032] A capacitive non-contact sensor is provided, which is obtained by stacking the hydrogel and Ecoflex film obtained in the above steps in a layer-by-layer manner; the number of stacked layers is 3 or 4. Preferably, the Ecoflex film is formed by uniformly mixing Ecoflex components A and B in a 1:1 ratio and placing it at a high temperature for 20 min to 60 min.

[0033] Example 1:

[0034] The preparation method of the multifunctional flexible conductive organic hydrogel in this embodiment includes the following steps:

[0035] (1) Dissolve 0.2g CS in 10mL of deionized water containing 2% acetic acid and stir at room temperature for 5h to obtain a homogeneous solution;

[0036] (2) Add 1.6g AA, 0.6g SBMA and 0.2g LiCl to the above solution and stir at room temperature for 2h; dissolve 0.6g MEA in 5mL DMSO, mix well and add to the above mixed solution;

[0037] (3) Add 0.016g of photoinitiator 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylacetophenone (HHMP) and 0.0048g of crosslinking agent N,N-methylenebisacrylamide (MBA) to the solution and stir magnetically for 2h.

[0038] (4) The mixed solution obtained in step (3) is degassed under vacuum and filled with nitrogen, then injected into an organic glass mold and photopolymerized under ultraviolet (365nm) irradiation for 15 minutes to obtain a multifunctional flexible conductive organic hydrogel.

[0039] (5) Mix components A and B of Ecoflex in a 1:1 ratio and place at a high temperature for 20 minutes to form an Ecoflex film. Then, assemble the hydrogel obtained in step (4) and the Ecoflex film into a sandwich-structured triboelectric nanogenerator (TENG). Alternatively, stack the hydrogel obtained in step (4) and the Ecoflex film layer by layer to obtain a 4-layer capacitive non-contact sensor.

[0040] The hydrogel prepared in this embodiment has good tensile properties and can be twisted and bent. It can also easily lift a 100g weight, demonstrating the good mechanical properties of the hydrogel. It can be seen that the dual network system of CS and P (AA-co-SBMA-co-MEA) makes up for the poor mechanical properties of single network hydrogels.

[0041] AA and SBMA impart adhesive properties to the hydrogel. The gel prepared in this embodiment can adhere firmly to various surfaces, including nitrile gloves, paper, plastics, glass, etc., which demonstrates the good adhesive properties of the prepared hydrogel.

[0042] The addition of LiCl and DMSO can improve the conductivity and antifreeze / moisturizing properties of the hydrogel. Figure 1 This diagram illustrates the sensing performance of a hydrogel sensor for human motion. Due to the excellent self-adhesive properties of conductive organic hydrogels, they can adhere tightly to the human body surface to detect various movements. For example, they can accurately detect the bending movements of fingers and wrists. The left graph shows the finger bending detection curve, and the right graph shows the wrist bending detection curve. The vertical axis represents the relative resistance change, used to evaluate the sensor's sensitivity. Figure 2 The TENG assembled with hydrogel and Ecoflex film was shown to harvest external mechanical energy and convert it into electrical energy. Figure 3 This demonstrates that a capacitive non-contact sensor assembled with hydrogel and Ecoflex film can identify the distance between a finger and the sensor based on changes in capacitance; it also demonstrates the sensing sensitivity of the non-contact sensor.

[0043] Example 2:

[0044] The preparation method of the multifunctional flexible conductive organic hydrogel in this embodiment includes the following steps:

[0045] (1) Dissolve 0.2g CS in 8mL of deionized water containing 2% acetic acid and stir at room temperature for 5h to obtain a homogeneous solution;

[0046] (2) Add 3g AA, 1.2g SBMA and 0.6g LiCl to the above solution and stir at room temperature for 2h; dissolve 2.4g MEA in 20mL DMSO, mix well and add to the above mixed solution;

[0047] (3) Add 0.15g of photoinitiator 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylacetophenone (HHMP) and 0.045g of crosslinking agent N,N-methylenebisacrylamide (MBA) to the solution and stir magnetically for 2h;

[0048] (4) The mixed solution obtained in step (3) is degassed under vacuum and filled with nitrogen, then injected into an organic glass mold and photopolymerized under ultraviolet (365nm) irradiation for 45 minutes to obtain a multifunctional flexible conductive organic hydrogel.

[0049] (5) Mix components A and B of Ecoflex in a 1:1 ratio and place at a high temperature for 60 min to form an Ecoflex film. Then, assemble the hydrogel obtained in step (4) and the Ecoflex film into a sandwich-structured triboelectric nanogenerator (TENG). Alternatively, stack the hydrogel obtained in step (4) and the Ecoflex film layer by layer to obtain a 3-layer capacitive non-contact sensor.

[0050] Example 3:

[0051] The preparation method of the multifunctional flexible conductive organic hydrogel in this embodiment includes the following steps:

[0052] (1) Dissolve 0.2g CS in 10mL of deionized water containing 2% acetic acid and stir at room temperature for 5h to obtain a homogeneous solution;

[0053] (2) Add 2g AA, 1g SBMA and 0.3g LiCl to the above solution and stir at room temperature for 2h; dissolve 1g MEA in 10mL DMSO, mix well and add to the above mixed solution;

[0054] (3) Add 0.1g of photoinitiator 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylacetophenone (HHMP) and 0.02g of crosslinking agent N,N-methylenebisacrylamide (MBA) to the solution and stir magnetically for 2h;

[0055] (4) The mixed solution obtained in step (3) is degassed under vacuum and filled with nitrogen, then injected into an organic glass mold and photopolymerized under ultraviolet (365nm) irradiation for 30 minutes to obtain a multifunctional flexible conductive organic hydrogel.

[0056] (5) Mix components A and B of Ecoflex in a 1:1 ratio and place at a high temperature for 40 minutes to form an Ecoflex film. Then, assemble the hydrogel obtained in step (4) and the Ecoflex film into a sandwich-structured triboelectric nanogenerator (TENG). Alternatively, stack the hydrogel obtained in step (4) and the Ecoflex film layer by layer to obtain a 4-layer capacitive non-contact sensor.

[0057] Example 4:

[0058] The preparation method of the multifunctional flexible conductive organic hydrogel in this embodiment includes the following steps:

[0059] (1) Dissolve 0.2g CS in 8mL of deionized water containing 2% acetic acid and stir at room temperature for 5h to obtain a homogeneous solution;

[0060] (2) Add 2.5g AA, 1.2g SBMA and 0.5g LiCl to the above solution and stir at room temperature for 2h; dissolve 2g MEA in 8mL DMSO, mix well and add to the above mixed solution;

[0061] (3) Add 0.12g of photoinitiator 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylacetophenone (HHMP) and 0.03g of crosslinking agent N,N-methylenebisacrylamide (MBA) to the solution and stir magnetically for 2h;

[0062] (4) The mixed solution obtained in step (3) is degassed under vacuum and filled with nitrogen, then injected into an organic glass mold and photopolymerized under ultraviolet (365nm) irradiation for 20 minutes to obtain a multifunctional flexible conductive organic hydrogel.

[0063] (5) Mix components A and B of Ecoflex in a 1:1 ratio and place at a high temperature for 30 min to form an Ecoflex film. Then, assemble the hydrogel obtained in step (4) and the Ecoflex film into a sandwich-structured triboelectric nanogenerator (TENG). Alternatively, stack the hydrogel obtained in step (4) and the Ecoflex film layer by layer to obtain a 3-layer capacitive non-contact sensor.

[0064] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be defined by the claims.

Claims

1. A method for preparing a multifunctional flexible conductive organic hydrogel, characterized in that, Includes the following steps: S1) Dissolve chitosan in acidic deionized water and stir at room temperature to obtain a homogeneous solution; S2) Add acrylic acid, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide and LiCl to the solution in S1 and continue stirring at room temperature; dissolve 2-methoxyethyl acrylate in dimethyl sulfoxide, mix well and then add it to the above mixed solution; S3) Continue to add the photoinitiator 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylacetophenone and the crosslinking agent N,N-methylenebisacrylamide to the mixed solution of S2, and stir magnetically; S4) The mixed solution obtained in step S3 is degassed under vacuum and photopolymerized by ultraviolet irradiation to obtain a multifunctional flexible conductive organic hydrogel. The deionized water in step S1 contains 2% acetic acid, the chitosan has a mass fraction of 2%-5%, and the stirring time is 2h-5h. The mass ratio of acrylic acid to chitosan is 8:1-15:1; the mass ratio of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide to chitosan is 3:1-6:1; the mass ratio of LiCl to chitosan is 1:1-3:1; the mass ratio of 2-methoxyethyl acrylate to [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide is 1:1-2:1; and the volume ratio of dimethyl sulfoxide to deionized water is 1:2-2:

1. The photoinitiator 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylacetophenone has a mass of 1-5 wt% of acrylic acid, and the crosslinking agent N,N-methylenebisacrylamide has a mass of 0.3-1.5 wt% of acrylic acid.

2. The preparation method of the multifunctional flexible conductive organic hydrogel as described in claim 1, characterized in that, In step S4, the ultraviolet irradiation time is 15-45 minutes.

3. The preparation method of the multifunctional flexible conductive organic hydrogel as described in claim 1, characterized in that, The stirring time in step S2 is 30 min-120 min, the stirring time in step S3 is 1 h-3 h, and the photopolymerization in step S4 is carried out by ultraviolet irradiation under inert gas protection.

4. A multifunctional flexible conductive organic hydrogel, characterized in that, It is prepared by the preparation method according to any one of claims 1-3.

5. A triboelectric nanogenerator, characterized in that, It is assembled from a multifunctional flexible conductive organic hydrogel as described in claim 4 and an Ecoflex film in a sandwich structure.

6. A capacitive non-contact sensor, characterized in that, It is obtained by stacking a multifunctional flexible conductive organic hydrogel as described in claim 4 with an Ecoflex film.

7. The capacitive non-contact sensor as described in claim 6, characterized in that, The Ecoflex film is formed by uniformly mixing Ecoflex components A and B in a 1:1 ratio and placing it at a high temperature for 20 min-60 min; the number of stacked layers is 3 or 4.

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