TWI727390B - Hydrogel, organic memory device and conductive polymer hydrogel system comprising the hydrogel, supercapacitor device comprising the conductive polymer hydrogel system, and methods for fabricating the hydrogel and the conductive polymer hydrogel system - Google Patents

Abstract

The present invention provides a hydrogel, an organic memory device and a conductive polymer hydrogel system comprising the hydrogel, a supercapacitor device comprising the conductive polymer hydrogel system, and methods for fabricating the hydrogel and the conductive polymer hydrogel system. The hydrogel comprises a polymer network of poly(vinyl alcohol) (PVA) and poly(methacrylic acid) (PMAA); wherein the polymer network comprising a cross-linker which is an organic compound having a plurality of hydroxyl group. The hydrogel has strong and stretchable mechanical properties after absorbing moisture from the ambient air, and can be recycled for several times since the cross-linking connection inside the gel were consisted of hydrolysable ester bonds.

Description

Hydrogel, organic memory device and conductive polymer hydrogel system including the hydrogel, ultracapacitor device including the conductive polymer hydrogel system, and the hydrogel and the conductive polymer hydrogel System preparation method

The invention relates to a flexible material, an electronic device and a system using the material. More specifically, the present invention relates to a polymer hydrogel, an organic memory device containing the hydrogel, and a conductive polymer hydrogel system, and an ultracapacitor device containing the conductive polymer hydrogel system , And the preparation method of the hydrogel and the conductive polymer hydrogel system.

Electronic devices with skin-like characteristics can bridge human tissues and electronic functions, and stimulate a variety of biological-related applications, such as implantable physiological monitoring devices and wearable healthcare tracking devices. In order to simulate human skin, the substrate and conductive material need to be soft and highly stretchable to adapt to deformation. The mechanical properties should be similar to the skin (0.02-0.5MPa) to prevent mechanical mismatch, which may cause serious interface delamination between the electronic device and the soft human body, or cause the recording of the electronic device of the wearable force sensor Distorted with stimuli. On the other hand, biocompatible electronic components suitable for long-term monitoring of the human body in medical and health care are also an important issue. Stretchable electronic devices that simulate the characteristics of human skin to detect important signals of the body are a rapidly emerging technology field. It is foreseeable that the commercialization of various applications that integrate stretchable circuits (such as smart sensors, artificial skins and prostheses, etc.) will become the main focus of the next decade.

At the same time, how to reduce environmental pollutants and energy consumption caused by modern consumer electronic products has also become the focus of public attention. Generally, most typical chip arrays are formed by their mechanical support substrate, which facilitates the electrical interconnection of the mounted components. At present, substrates used for stretchable electronic products are usually made of non-decomposable and non-biocompatible materials, causing serious ecological problems around the world. The use of renewable or recyclable "green" substrates in electronic products can prevent the growth of solid waste accumulation in waste landfills. At present, efforts have been devoted to the development of non-toxic and renewable electronic device substrates, such as polysaccharides, silk and cellulose nanofibers. However, the mechanical properties of these substrates are not sufficient to adapt to the large deformation under stretching, so they are not suitable for stretchable devices. It is still a key challenge to build a substrate that is highly stretchable and recyclable and suitable for flexible electronic products.

As we all know, hydrogels are soft materials derived from organisms that can simulate the mechanical properties of human skin. Studies have been conducted to combine conjugated polymers such as polydioxyethylthiophene: poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT: PSS), polyaniline (PANi) or polypyrrole (polypyrrole). , PPy) is made into a crosslinkable hydrated matrix polymer made of conductive polymer hydrogels (electrically conducting polymer hydrogels, CPHs), which are used in electrical interconnections, supercapacitors, batteries and sensors. In the manufacture of stretchable electronic devices, the attractive properties of hydrogel can outperform other soft materials, especially for the application of human-friendly wearable or implantable devices.

However, the following key challenging issues hinder the practical application of conductive polymer hydrogels for integrated electronic devices: (1) Air stability: The main component of typical hydrogels is water (usually more than 70%), which is unique The properties such as stretchability and ion conductivity strongly depend on the water medium. However, the water in the hydrogel tends to evaporate over time under environmental conditions. (2) Preparation method: Generally, the method for preparing conductive polymer hydrogel includes the following two steps. First, prepare a pre-mixed solution containing hydrophilic monomers, initiators and crosslinking agents in water, and then heat the solution to induce gelation. Secondly, the hydrogel is immersed in the second monomer solution for in-situ polymerization of the conductive polymer. The above method cannot be used to manufacture mass-produced electronic devices. In addition, conductive polymer hydrogels require a long cleaning time to remove unreacted initiators and crosslinking agents, such as the commonly used initiator-ammonium persulfate.

In order to overcome the above shortcomings, the main purpose of the present invention is to provide a hydrogel, including: a polymer network, which is poly(vinyl alcohol) (PVA) and poly(methacrylic acid) , PMAA) polymer network; wherein the polymer network includes a cross-linking agent, the cross-linking agent is an organic compound with a plurality of hydroxyl groups.

Further, the crosslinking agent is ethylene glycol (EG).

Further, the mass ratio of the PVA: the PMAA ranges from 2:1 to 1:2.

Further, the mass ratio of the PVA: the PMAA is 1:1.

Another object of the present invention is to provide a method for preparing the above-mentioned hydrogel, the steps of which include: a. dissolving polymer PVA and PMAA in an organic compound having a plurality of hydroxyl groups to form a polymer solution; b. Heating the polymer solution; and c. injecting the polymer solution into a mold and heating it for cross-linking reaction.

Another object of the present invention is to provide an organic memory device, including: a bottom electrode layer; a top electrode layer; a base layer disposed under the bottom electrode layer, the base layer including the above-mentioned hydrogel; And a memory layer, which is arranged between the bottom electrode layer and the top electrode layer, and the memory layer includes a deoxyribonucleic acid (DNA).

Further, the bottom electrode layer and the top electrode layer include a conductive polymer, and the conductive polymer is selected from a polyacetylene-based polymer and a polyphenylenevinylene-based polymer. , Polyaniline (PANi), polypyrrole-based polymer, polythiophene-based polymer, polythiophenevinylene-based polymer, and polydioxide Ethylthiophene: a group consisting of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT: PSS).

Further, the bottom electrode layer and the top electrode layer include a polymer blend of PEDOT:PSS and water-soluble polyurethane (PU).

Further, the bottom electrode layer and the top electrode layer include a polymer blend of PEDOT:PSS and water-soluble polyurethane, and the ratio of PEDOT:PSS to water-soluble polyurethane in the polymer blend is 1:4 .

Another object of the present invention is to provide a conductive polymer hydrogel system, comprising: the above-mentioned hydrogel; and a conductive material distributed in the polymer network.

Further, the conductive material is an acid, a base or a salt, and the conductive polymer hydrogel system forms an ion conductive hydrogel.

Further, the acid is selected from the group consisting of sulfuric acid, phosphoric acid and perchloric acid.

Furthermore, the alkali is potassium hydroxide (KOH).

Further, the salt is selected from the group consisting of lithium chloride (LiCl), lithium perchlorate (LiClO ₄ ), and potassium chloride (KCl).

Further, the conductive material is selected from polyacetylene-based polymers, poly(p-styrene-based polymers, polyaniline, polypyrrol-based polymers, polythiophene-based polymers, polythiophene vinylidene polymers, and PEDOT: PSS). And the conductive polymer hydrogel system forms an electronically conductive hydrogel.

Further, the ion conductive hydrogel is an electrolyte, and the electrolyte is arranged in an ultracapacitor device.

Another object of the present invention is to provide a supercapacitor device, comprising: at least two electrodes; and an electrolyte, which is arranged between the electrodes; wherein the electrode and the electrolyte are made of the aforementioned conductive polymer hydrogel system The conductive material of the electrode is an electronic conductive material, and the conductive material of the electrolyte is an ion conductive material.

Further, the electronically conductive material is a conductive polymer, and the conductive polymer is selected from polyacetylene-based polymers, poly(p-styrene-based polymers, polyaniline, polypyrrol-based polymers, polythiophene-based polymers, and polyphenylene-based polymers). Thiophene vinylidene polymer and PEDOT: a group consisting of PSS.

Further, the electronically conductive material is PEDOT:PSS.

Further, the ion conductive material is an acid, a base or a salt.

Further, the acid is selected from the group consisting of sulfuric acid, phosphoric acid and perchloric acid; the base is KOH; and the salt is selected from the group consisting of _{LiCl, LiClO 4 and KCl.}

Yet another object of the present invention is to provide a method for preparing the above-mentioned conductive polymer hydrogel system, the steps of which include: a. Dissolving polymers PVA and PMAA in an organic compound having a plurality of hydroxyl groups to form a polymer Solution and heating the polymer solution; b. adding the conductive material to the polymer solution and mixing; and c. injecting the aforementioned mixed solution into a mold and heating for cross-linking.

As mentioned above, the present invention has the following advantages over the prior art:

1. The hydrogel of the present invention is hygroscopic. The hydrogel of the present invention can overcome the shortcomings of conventional high-strength hydrogels that cannot be recycled, reused or reprocessed. The present invention provides a new strategy for absorbing water molecules from the surrounding environment as a plasticizer to increase chain mobility and make the hydrogel softer, instead of rehydration by immersing the hydrogel in water as in the prior art.

2. In the present invention, the hydrogel can be prepared by a simple method, that is, mixing two hydrophilic polymers, PVA and PMAA, and using organic compounds with multiple hydroxyl groups as solvents and crosslinking agents. In the prior art, the biodegradable elastic system is prepared by condensation reaction under vacuum and high temperature conditions. In contrast, the method for preparing hydrogel of the present invention is simpler and has low energy consumption.

3. The organic memory device of the present invention is a stretchable, stable and water-soluble resistive "memory device" that uses DNA as a memory element. It is also a polymer blend used as a stretchable electrode , Which is based on the hydrogel of the present invention as the substrate. It is worth noting that DNA is an attractive natural environmentally friendly polymer. As far as we know, the present invention is the first stretchable resistive organic memory fabricated on a hydrogel substrate.

4. The present invention also provides a conductive polymer hydrogel system with high conductivity and excellent stretchability, and a fast and environmentally friendly method for preparing the conductive polymer hydrogel system. The conductive polymer hydrogel system of the present invention can be used in current collectors and electrode materials to prepare the ultracapacitor device of the present invention.

5. The ultracapacitor device of the present invention prevents the inherent problems of delamination, displacement and strain adjustment engineering in traditional laminated stretchable ultracapacitors. Ultracapacitor devices provide large deformations (up to 100% strain) without affecting electrochemical performance. More importantly, the electrochemical performance of the ultracapacitor device of the present invention can still be preserved well under a tensile strain of 30% for 1000 times. The present invention not only creates an effective platform for stretchable ultracapacitor devices used in modern flexible electronic products and skin-like wearable devices, but also implements environmentally sustainable environmental protection methods.

The detailed description and technical content of the present invention will now be described in conjunction with the drawings as follows. Furthermore, the figures in the present invention are not necessarily drawn according to actual proportions for the convenience of description, and these figures and their proportions are not used to limit the scope of the present invention, and are described here first.

Unless otherwise defined, the meanings of all technical and scientific terms used herein are the same as those commonly understood by those of ordinary skill in the art to which the present invention belongs. The following terms used throughout this application shall have the following meanings.

Unless otherwise stated, "or" means "and/or". "Including" means that it does not exclude the presence or addition of one or more other components, steps, operations or elements to the described components, steps, operations or elements. Similarly, "include" and "include" are interchangeable and not restrictive. The singular forms "a" and "the" used in the scope of this document and the appended applications include plural referents unless the context dictates otherwise. For example, the terms "a", "the", "one or more" and "at least one" are used interchangeably herein.

The present invention relates to a hydrogel 100, which includes: a polymer network 11, which is poly(vinyl alcohol) (PVA) 111 and poly(methacrylic acid) (PMAA) 112 The polymer network; wherein the polymer network 11 includes a cross-linking agent 113, the cross-linking agent 113 is an organic compound with a plurality of hydroxyl groups (see Figure 1). The present invention also provides a method for preparing the above-mentioned hydrogel, which includes the following steps: a. dissolving the polymer PVA and PMAA in an organic compound having a plurality of hydroxyl groups to form a polymer solution; b. heating the polymer solution ; And c. Inject the polymer solution into a mold and heat it for cross-linking reaction.

In this context, "hydrogel" means polymer hydrogel. PVA has been widely developed for hydrogels, however, it is well known that the chain mobility of PVA is limited by its crystal domains, which also inhibits the diffusion of water molecules from the surrounding air into the substrate. Therefore, the present invention uses the amorphous polymer PMAA to reduce the crystal domains of PVA and increase the flexibility of the hydrogel. In an embodiment, the mass ratio of PVA:PMAA ranges from 2:1 to 1:2, including but not limited to: 2:1, 1.9:1, 1.8:1, 1.7:1, 1.6:1, 1.5: 1. 1.4:1, 1.3:1, 1.2:1, 1.1:1, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9 or 1:2. In a preferred embodiment, the mass ratio of PVA:PMAA is 1:1.

The term "polymer network" refers to mechanical strength. The formation of dual-network hydrogels is an innovative and effective method to improve the mechanical properties of hydrogels. The ideal double network structure consists of two chemical bonds, one is a long chain with covalent linkage, and the other is a shorter chain with sacrificial reversible bonding. Generally, the toughness of the gel comes from the sacrificial bonds on the short chains (such as hydrogen bonds, ionic bonds, hydrophobic interactions, and crystallites) before the stronger bonds on the longer, more densely cross-linked long chains are broken.的rupture. However, due to the high water content (40-80%) of this method, and the loss of water will affect the size, shape and most importantly, the mechanical properties, the suitability of this method for green electronic equipment substrates still has disadvantages. . In addition, high-strength hydrogels usually require a large number of permanent cross-linking points in the three-dimensional network, and strong chain entanglement within the structure, so the resulting gel usually cannot be recycled or reprocessed. Therefore, the polymer network contained in the present invention provides a new strategy for preparing a strong hydrogel with air stability and recyclability for electronic device applications.

The polymer network of PVA and PMAA (abbreviated as PVA-PMAA network herein) contains a crosslinking agent. In an embodiment, the cross-linking agent is an organic compound having a plurality of hydroxyl groups; wherein, this embodiment brings about the effect of covalently cross-linking the PVA-PMAA network by the organic compound. In a preferred embodiment, the cross-linking agent is ethylene glycol (EG); therefore, the PVA-PMAA network is covalently cross-linked through EG. Note that both PVA and PMAA have functional groups to react with organic compounds having at least two hydroxyl groups (such as EG) through condensation to form a covalent crossover network. Organic compounds with multiple hydroxyl groups can function as hygroscopic solvents and crosslinking agents. Therefore, the hydrogel of the present invention has strong and stretchable mechanical properties after absorbing moisture from the ambient air, and since the cross-linking connection inside the hydrogel is composed of hydrolyzable ester bonds, it can be recycled repeatedly.

In one embodiment, the hydrogel is produced by mixing two hydrophilic polymers PVA and PMAA with an organic compound having a plurality of hydroxyl groups as a solvent and a crosslinking agent. In a preferred embodiment, the hydrogel is produced by mixing two hydrophilic polymers, PVA and PMAA, with EG as a solvent and crosslinking agent. Compared with the prior art of preparing a biodegradable elastomer through a condensation reaction under vacuum and high temperature conditions, the method for producing a hydrogel of the present invention is relatively simple and has low energy consumption.

The hydrogel of the present invention is a hygroscopic hydrogel. The new strategy of the present invention is to absorb water molecules from the surrounding environment as a plasticizer to increase chain mobility and make the hydrogel softer, instead of rehydrating by immersing the hydrogel in water as in the prior art. Different from the typical stretchable electronic substrate layer in the prior art (such as silicon-based polymer or polydimethylsiloxane (PDMS)) due to its inherent characteristics (such as poor mechanical toughness, high water content and solvent evaporation) ) Without a way to directly integrate into electronic devices, the hydrogel of the present invention overcomes these problems and increases its applicability in flexible or stretchable electronic devices. In addition, the water inside the hydrogel may form a dynamic balance with the surrounding water, so its stretchability can be maintained for a long time, which has application potential for stretchable electronic products.

15, the present invention further relates to an organic memory device 200, which includes a bottom electrode layer 23, a top electrode layer 22, a base layer 21, and a memory layer 24. The base layer 21 is disposed under the bottom electrode layer 23, and the base layer 21 includes the above-mentioned hydrogel. The memory layer 24 is disposed between the bottom electrode layer 23 and the top electrode layer 22, and the memory layer 24 includes a deoxyribonucleic acid (DNA).

In one embodiment, the bottom electrode layer and the top electrode layer include a conductive polymer, and the conductive polymer is selected from polyacetylene-based polymers and polyphenylenevinylene-based polymers. based polymer), polyaniline (PANi), polypyrrole-based polymer, polythiophene-based polymer, polythiophenevinylene-based polymer, and Polydioxyethylthiophene: a group consisting of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT: PSS). In a preferred embodiment, the bottom electrode layer and the top electrode layer include a polymer blend of PEDOT:PSS and water-soluble polyurethane (PU). In a preferred embodiment, the bottom electrode layer and the top electrode layer include a polymer blend of PEDOT:PSS and PU, and the ratio of PEDOT:PSS to PU in the polymer blend is 1: 2 to 1:5, including but not limited to 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5 or 1:5. In a preferred embodiment, the bottom electrode layer and the top electrode layer include a polymer blend of PEDOT:PSS and PU, and the ratio of PEDOT:PSS to PU in the polymer blend is 1: 4.

The organic memory device of the present invention is a stretchable, stable, and water-soluble resistive memory device, which is based on the hydrogel of the present invention as a base layer, and uses DNA as a memory element and a polymer blend (Such as PEDOT: PSS/PU) as a stretchable electrode. In this article, the "memory layer" includes natural environmentally friendly polymer DNA. As far as we know, this is the first publication to prepare a stretchable resistive organic memory device on a hydrogel substrate layer.

The present invention further relates to a conductive polymer hydrogel system, which includes: the above-mentioned hydrogel; and a conductive material distributed in the polymer network. The present invention also provides a method for preparing the aforementioned conductive polymer hydrogel system. The steps include: a. Dissolving polymers PVA and PMAA in an organic compound with multiple hydroxyl groups to form a polymer solution, and heating the Polymer solution; b. adding the conductive material to the polymer solution and mixing; and c. injecting the aforementioned mixed solution into a mold and heating for cross-linking.

The term "conductive material" used in the conductive polymer hydrogel system of the present invention means a material distributed in the polymer network of the hydrogel of the present invention or a material incorporated into the hydrogel (PVA/PMAA/ The material of the cross-linking agent (gel) solution is used to make the hydrogel form a conductive hydrogel. In one embodiment, the aforementioned conductive hydrogel may be an ion conductive hydrogel (ie, an ion conductive polymer hydrogel system) or an electronically conductive hydrogel (ie, an electronic conductive polymer hydrogel system).

In one embodiment, the conductive material is an acid, a base or a salt, and the conductive polymer hydrogel system forms an ion conductive hydrogel. For example, but not limited to, the acid can be selected from the group consisting of sulfuric acid, phosphoric acid (H ₃ PO ₄ ) and perchloric acid (HClO ₄ ); the base can be potassium hydroxide (KOH); the salt can be free of chlorine Lithium chloride (LiCl), lithium perchlorate (LiClO ₄ ), and potassium chloride (KCl). In an alternative embodiment, the ion-conducting hydrogel is an electrolyte, that is, a hydrogel-based electrolyte (or abbreviated as hydrogel electrolyte herein). In an alternative embodiment, the ion-conducting hydrogel is disposed in an electrolyte in an ultracapacitor device. In one embodiment, an independent hydrogel electrolyte can be prepared by mixing the hydrogel solution with an acid as a proton, and then crosslinking and wetting the hydrogel. The program may be crosslinked and wetting such as, but not limited to: a left under ambient conditions (25 ^o C, 60% relative humidity) for 24 hours. In a more preferred embodiment, the conductive polymer hydrogel system includes: the above-mentioned hydrogel; and H ₃ PO ₄ as a conductive material is distributed in the polymer network of the hydrogel, thereby forming an electrolyte . Compared with the conventional stretchable electrolyte (such as H ₃ PO ₄ -PVA) in the prior art, the electrolyte of the present invention has higher electrical conductivity and stretchability.

In alternative embodiments, the conductive material is selected from polyacetylene-based polymers, poly(p-styrene-based polymers, polyaniline, polypyrrol-based polymers, polythiophene-based polymers, and polythiophene vinylidene polymers). And PEDOT: A group consisting of PSS, and the conductive polymer hydrogel system forms an electronically conductive hydrogel. In a preferred embodiment, the conductive polymer hydrogel system is an electronically conductive hydrogel, and the conductive material includes PEDOT:PSS.

The present invention also relates to a supercapacitor device, including: at least two electrodes; and at least one electrolyte, which is arranged between the electrodes. The electrode and the electrolyte are made of the aforementioned conductive polymer hydrogel system, the conductive material of the electrode is an electronic conductive material, and the conductive material of the electrolyte is an ion conductive material.

In one embodiment, the electronically conductive material is a conductive polymer, and the conductive polymer is selected from the group consisting of polyacetylene-based polymers, poly(p-styrene-based polymers, polyaniline, polypyrrol-based polymers, and polythiophene-based polymers). Compounds, polythiophene vinylene polymers and PEDOT: a group consisting of PSS. In a preferred embodiment, the electronically conductive material is PEDOT:PSS.

In one embodiment, the ion conductive material is an acid, a base, or a salt. For example, but not limited to, the acid can be selected from the group consisting of sulfuric acid, phosphoric acid, and perchloric acid; the base can be KOH; The salt can be selected from the group consisting of _{LiCl, LiClO 4 and KCl.}

In one embodiment, the conductive polymer hydrogel system (300, 400) is achieved by incorporating conductive materials (35, 45) into the hydrogel (PVA 32, 42/PMAA 33, 43/crosslinking agent 34, 44). ) Solution (31, 41), as shown in Figure 3 (a) and (b); then, through simple solution casting, and then ^{cross-linking at 150 o} C under ambient conditions to form ionic or electronic conductivity Hydrogel (300, 400). In one embodiment, a conductive polymer hydrogel system is prepared by mixing conductive materials into a hydrogel (PVA/PMAA/EG gel) solution, and then through simple solution casting, and then under ambient conditions Cross-link at 150 ^o C to form ionic or electronic conductive hydrogel.

In one embodiment, the electrode is prepared through the same cross-linking and wetting procedure as the method for preparing the electrolyte described above, and the electrode is used as the electrode material of the stretchable ultracapacitor device. In one embodiment, the ultracapacitor device 500 includes a structure of electrode 51/electrolyte 52/electrode 51, as shown in FIG. 3(d). In a preferred embodiment, the structure of the ultracapacitor device includes: PEDOT: PSS hydrogel/(PVA/PMAA/H ₃ PO ₄ ) hydrogel/PEDOT: PSS hydrogel; wherein the aforementioned PVA/PMAA/H ₃ PO ₄ hydrogels are used as electrolytes, and the aforementioned PEDOT:PSS hydrogels are used as electrode materials and current collectors. The ultracapacitor device of the present invention is stretchable and has potential applications as a power source to supply electronic equipment, eliminating bulky wires and realizing a portable and integrated device system.

Hereinafter, the present invention will be explained in more detail through exemplary embodiments. Although the exemplary embodiments are disclosed herein, it should be understood that they are used to illustrate the present invention and not to limit the scope of the present invention. Example 1 : Hydrogel, organic memory device and its preparation method A. Experiment (1) Material

Polyvinyl alcohol (PVA) (degree of hydrolysis 87-90%, average molecular weight 30,000-70,000) and ethylene glycol (EG) (99.8% anhydrous) were purchased from Sigma-Aldrich. Polymethacrylic acid (PMAA) was purchased from Scientific Polymer Products. Polyurethane (PU) dispersion (Alberdingk® U 3251) was purchased from Alberdingk Boley. Zonyl FS-300 fluorosurfactant (Zonyl, _{about 40% solid content in H 2} O) was purchased from Fluka Analytical. PH1000 PEDOT: PSS was purchased from Uni Region Biotech. Deoxyribonucleotide sodium salt was purchased from MP Biomedicals LLC. Trimethoxy(octadecyl)silane (OTS) was purchased from Gelest Company. All materials can be used without further purification. (2) Preparation Example Hydrogel

Prepare polymer/EG solutions with different mass ratios (PVA:PMAA=1:0, 2:1, 1:1, 1:2, and 0:1) at a concentration of 200 mg/mL, and stir at 60°C, A viscous but homogeneous solution is obtained. Then pour the mixed solution into a clean Teflon mold and ^{heat it at 200 o} C for different hours. (3) Characteristics of Example Hydrogel

Thermogravimetric analysis (TGA) was performed using a Q50 instrument from TA Instruments. Heat 9-12 mg of basal layer ^{at a heating rate of 10 o} C/min from 100 to 600 ^o C under nitrogen flow (flow rate 40 mL/min). Differential scanning calorimetry (Differential scanning calorimetry, DSC) curve is obtained by using TA Instruments' Q100 instrument and ^{heating from 0 o} C to 250 ^o C at a heating rate of ^{5 o C/min.} Nitrogen is the carrier gas with a flow rate of 50 mL/min. X-ray diffraction analysis (XRD) was performed using PANalytical's X'Pert in the 2θ range of 10-60 degrees. Use PerkinElmer's Spectrum Two FT-IR Spectrometer (Fourier-transform infrared spectroscopy, FT-IR) in the wavenumber range of ^{4000 to 450 cm -1.} The stress-strain, stress relaxation, and load-unload curves were obtained by TA Instruments' DMA Q800 type instrument. For the stress-strain curve, an incremental force of 0.2 N/min to 18.0 N is used. (4) Water content measurement

(5)水中水解測定First put the prepared example hydrogel (1×2 cm) in a vacuum chamber and ^{place it under a pressure of 1×10 -3} torr for 1 day to remove the solvent and absorbed water during the cross-linking process, and then Put it under ^{the environmental conditions of 25 o} C and 60% relative humidity. The water content W (%) is defined as shown in the following formula (1), where W _o is the initial weight of the hydrogel, and W _m is the weight of the hydrogel after different hours of rehydration under ambient conditions.

(5) Determination of hydrolysis in water

(6) 實施例有機記憶體裝置的製備和特性Weigh the prepared example hydrogel (1×2 cm), immerse it in water without any stirring, and keep the temperature at 25°C. Take out the hydrogel regularly, blot it dry with soft paper to remove surface moisture, dry it in a vacuum at ambient temperature, and then weigh it again. The definition of the degree of hydrolysis is shown in the following formula (2), where D _o is the initial weight of the hydrogel, and D _m is the weight of the hydrogel after being hydrolyzed in water for different periods of time.

(6) Preparation and characteristics of organic memory device of the embodiment

The organic memory device of this embodiment was prepared on the hydrogel PVA: PMAA (1:1) of the embodiment. The top and bottom electrode layers are made of PEDOT: a mixture of PSS and PU. PEDOT: PSS was prepared by mixing 20 mL of PH1000 PEDOT: PSS with 2 mL of dimethyl sulfoxide (DMSO) to improve electrical conductivity, and 200 μL of Zonyl as a surfactant. The PEDOT:PSS solution was stirred overnight at room temperature. The PU solution was prepared by dissolving 2 mL of 400 mg/mL PU in 20 mL of deionized water and stirring it overnight. Add all the PEDOT:PSS solution very slowly to the vigorously stirred PU solution to mix the two solutions. The solution mixture was mixed overnight before spraying. After that, the solution was passed through a polytetrafluoroethylene (PTFE) membrane syringe filter with a pore size of 0.45 μm, and filtered into the spraying cabin body. Using Scotch® tape as a light shield, a narrow 0.6 mm bottom gate (approximately 200 nm thick) was drawn on the hydrogel. Place the drawn hydrogel under the nozzle with a spray height of 23 cm, and set the heating plate under the hydrogel to 50 ^o C. The DNA sodium salt was dissolved in 1 mL of water at a concentration of 27 mg/mL to prepare a DNA solution. After stirring for 6 hours, 2 mL of methanol was added to reduce the concentration to 9 mg/mL. The mixed solution was stirred overnight and spin-coated on the bottom electrode at 800 rpm for 90 seconds. For the top electrode, the PEDOT:PSS/PU solution was sprayed onto the 300 nm silicon oxide wafer treated with OTS using the mask patterning. The spraying parameters are the same as the previous spraying of the bottom electrode. Then the top and bottom electrodes are aligned to form a cross section of 0.6 × 0.6 mm square ^2, followed by applying a small pressure to the top of the wafer OTS at 45 ^o C, thereby transferring the DNA to the top of the top electrode layer. Using Keithley 4200 semiconductor parameter analyzer, at 25 ^o C, 60% of the environmental conditions, electrical characteristics of examples of the organic memory device embodiment measured prepared, the organic memory device system A resistor type memory device relative humidity. B. Results (1) Preparation and characteristics of the hydrogel of the example and the hydrogel of the comparative example

PVA and PMAA concentrated in the aqueous solution can react with each other without a catalyst to form a comparative hydrogel. When two concentrated aqueous solutions of PVA and PMAA are mixed without any catalyst or cross-linking agent, gelation occurs. As shown in Figure 2, the comparative hydrogel was formed, and the hydrogel was precipitated from the water. However, since non-covalent hydrogen bonds are the main source of cross-linking points in the hydrogel, the hydrogel is fragile and fragile, and when left in the atmosphere, the water will evaporate and become hard. In contrast, the hydrogel of the example is made by dissolving PVA/PMAA in EG instead of water to reduce the strength of the hydrogen bond between PVA, PMAA and the solvent, thereby preventing excessive hydrogen bonding. The spontaneous precipitation between the components and the solvent often occurs in concentrated water systems. By eliminating the shortcomings of premature precipitation at high concentrations, the example hydrogels can be prepared by crosslinking the two polymers through a simple condensation reaction at high temperatures to form covalent bonds in the hydrogels. Mechanical properties. The polymer/EG solution was prepared with a concentration of 200 mg/mL and ^{stirred at 60 o} C to obtain a viscous but uniform solution. Then pour the mixed solution into a clean Teflon mold and ^{heat it at 200 o} C for 3 hours (Figure 1(a)). The condensation of EG and the hydroxyl or carboxyl group of the polymer is carried out at high temperature. After 3 hours, the cross-linking reaction of the gel occurred effectively in the solution state, forming three types of connections (Figure 1(b)), and obtaining gelation; the obtained hydrogel can absorb the surrounding air The moisture in M. During this so EG (boiling point 193 ^o C) unreacted evaporated to give an independent base layer. The polymer network in the example hydrogel contains both reversible hydrogen bonds and covalently cross-linked ester and ether bonds. This example further analyzes the influence of PMAA content on the water absorption, crystallinity and mechanical properties of the prepared hydrogel. The hydrogel is a PVA/PMAA blend (PVA: PMAA) with different mass ratios in EG. =1:0, 2:1, 1, 1:1, 1:2 and 0:1). Fourier-transform infrared spectroscopy (FTIR) analysis is used to gain insight into the structure of the blend network and the degree of cross-linking. Figure 4(a) shows the comparison of FTIR spectra of pure PVA, pure PMAA and hydrogels of various mixing ratios cast in EG. Compared with pure PVA, the OH stretch peak of the blend broadens and shifts to a higher wavenumber region, indicating that the hydrogen bond is stronger due to the strong dipole of the carboxyl group of PMAA. This analysis uses the intensity of the alkyl CH stretching peak (A ₂₉₃₀ ), which is substantially constant, as the standard peak to observe the degree of cross-linking with the cross-linking temperature and time. Figure 4(b) and (c) show that as the crosslinking time and temperature increase, the _{ratio of A 3320(-OH)} / A _2930(-CH) decreases, while the ratio of A _1178(-COC-) /A _{2930(-CH) decreases. ) The} ratio increases. In addition, the absorption intensity of the C=O group of PMAA also increases, as shown by the value of A _1700(-C=O) /A _2930(-CH) . The increase in the absorption strength of the carbonyl group can be attributed to the increase in the dipole moment of the C=O group, and the two share hydrogen bonds. The results confirmed that using EG as a solvent and a crosslinking agent at the same time can crosslink PVA and PMAA, and can adjust the hydrogen bond interaction by increasing the crosslinking time or temperature. The TGA spectra of the hydrogel of the example (hybrid hydrogel) and the hydrogel of the comparative example (pure composition) are shown in FIG. 5. In the TGA analysis curve, ^{there is no obvious discontinuity at ≈190 o} C, indicating that the residual amount of EG in the hydrogel is very small, so it is determined that the gel is "hydrogel" instead of "organogel"". Corresponding differential thermogravimetric (derivative thermogravimetry, DTG) analyzes show PVA FIG peak moves from 327 ^o C 296 ^o C, and the strength with increasing content of PMAA blend decreases. Furthermore, as the mixing ratio of the peak intensity increases PMAA at 425 ^o C. These results indicate that PVA and PMAA may have caused the cross-linking reaction in the hydrogel. (2) Water absorption and water retention of the hydrogel of the example

In the gel system, the water molecules trapped in the gel play a great role in improving the chain mobility of the polymer. Therefore, the ability of the gel to capture and retain water are two key attributes that directly reflect or even determine the mechanical properties of the hydrogel. Therefore, this example further studies the water absorption and water retention capacity of the example hydrogel (PVA-PMAA) prepared under environmental conditions. First, the hydrogels of the Examples and Comparative Examples were placed in a vacuum chamber for 1 day at a pressure of 1×10 ^-3 Torr to remove the water absorbed during the cross-linking process. The hydrogel is then rehydrated under environmental conditions of 60% relative humidity and 25 ^{o C.} Figure 6 shows the water content of pure PVA and pure PMAA cast in water and EG (as a comparative example); and the water content of three hydrogels with different mixing ratios cast in EG (as an example). The water content is defined as formula (1), where W _o is the initial weight of the hydrogel (measured immediately after vacuum treatment), and W _m is the weight of the hydrogel after rehydration. By using EG as a solvent, the water content (13%) of pure PVA cast in EG is higher than that of pure PVA cast in water (4%), so the water absorption rate is increased. This is because the residual EG in the gel (1) helps water absorption, because EG itself is a highly hygroscopic molecule called polyol; (2) as a plasticizer, it can increase the inter-molecular spacing and chain mobility , Thereby increasing water permeability. The moisture absorption rate of all the mixed hydrogels (ie the hydrogels of the examples) gradually increased over time, and reached an equilibrium value of about 25% after 24 hours. This is the pure PVA cast in EG (ie, the hydrogel of the comparative example). It is twice as high as the gel) and about a quarter higher than the pure PMAA cast in EG (ie, the hydrogel of the comparative example). The increase in its water content can be attributed to the fact that amorphous PMAA inhibits PVA from forming extensive crystal domains that are considered impermeable to water molecules. The results can be further verified through the corresponding XRD diagram, as shown in Figure 7. After pure PVA is mixed with PMAA, the crystallization peak of pure PVA broadens and becomes smaller, for each combination. Similar results were also observed in DSC analysis (Figure 8). Among them, the lack of endothermic melting peaks of PVA:PMAA (2:1), (1:1) and (1:2) hydrogels is most likely due to The amorphous structure of PMAA. In addition, in order to observe the extent to which the hydrogels of the examples can retain and maintain the absorbed water, the quality of the hydrogels under environmental conditions is recorded every day for 30 days. Figure 9 shows that the quality of the hydrogel of the example remained fairly constant and did not significantly decrease within 30 days. It means that the hydrogel of the present invention can maintain a dynamic water balance in the atmosphere, which can be attributed to the hydrophilic polymer chains and the strong hydrogen bonds formed between PVA and PMAA water. (3) Mechanical properties of the hydrogel of the embodiment

First observe the influence of water content on the mechanical properties of hydrogels. Figure 10(b) shows the stress-strain curves of example hydrogels (PVA:PMAA (1:1)) with different water contents. The decrease in water content leads to a sharp increase in the hardness of the hydrogel because water is the main chain plasticizer in the system. If the water content is increased to 22%, a two-level drop in Young's modulus can be observed (Table 1). It is worth noting that the water content in the hydrogel of the example only comes from the moisture in the atmosphere. Therefore, unlike conventional hydrogels, the example hydrogels (PVA-PMAA) do not need to be immersed in water for rehydration to obtain high stretchability. Figure 10(a) shows the visual images of the example hydrogel PVA:PMAA (1:1) under different strains. It can be seen that the hydrogel of the example can be stretched more than 200% without breaking. In order to understand the essential contribution of each component to the mechanical properties of the hydrogel of the present invention, stress-strain tests were performed on the example hydrogels of various mixing ratios, as shown in FIG. 10(c) and summarized in Table 2. Note that before the mechanical test, all the hydrogels of the examples were placed under environmental conditions for 1 day, so the water content of each hydrogel was ≈25%. The example hydrogels containing the PVA:PMAA (1:1) blend had the highest overall mechanical properties, with a Young's modulus of 0.75 MPa, a linear region of 42%, and an elongation at break of more than 550%. It can be observed that the stiffness of the hydrogel increases with higher PVA content, which can be attributed to the increase in crystal domains. Compared with pure PVA and PMAA (comparative examples), by optimizing the mixing ratio to 1:1, the elongation and linear region can be significantly increased to more than 550% and 42%, respectively. The underlying mechanism behind the superiority of the example hydrogel (blend) over the comparative example hydrogel (single-component hydrogel) may be due to its polymer network routing sacrificial hydrogen bonds and covalent cross-linking that can maintain the main backbone composition. In addition, energy dissipation tests were performed to confirm the presence of sacrificial hydrogen bonds in the polymer network. As shown in Figure 10(d), the PVA:PMAA (1:1) example hydrogel was subjected to 10 loading-unloading cycles, and the relaxation time was 1 minute. Obvious hysteresis can be observed, and the area between the loading curve and the unloading curve can be regarded as the energy consumed per unit volume. These hysteresis phenomena show that there are strong hydrogen bond interactions between the carboxyl groups, alcohol groups and water in the hydrogel network.

Table 1: The influence of moisture content on the Young's modulus of PVA:PMAA (1:1) Example hydrogel Water content (%) Young's modulus (MPa) 1.90 8.40 11.89 22.10 16.03 12.78 2.18 0.75

Table 2: Stress-strain curve data of comparative hydrogels (PVA, PMAA) and example hydrogels (blends) cast in EG. PVA 2:1 1:1 1:2 PMAA Young's modulus (MPa) ≈365.2 ≈1.68 ≈0.75 ≈0.48 ≈0.18 Linear area (%) ≈10.2 ≈30.0 ≈42.0 ≈22.0 ≈15.0 Elongation (%) ≈80.2 ≈250.7 >567.6 >553.1 ≈321.9

Fast and complete recovery is essential for integrating the gel base layer into stretchable electronic applications; therefore, the effect of mixing ratio on the recovery properties of the hydrogel was further examined. Figure 10(e) shows the strain-relaxation time test measured at 25% strain. Table 3 summarizes the individual 80% recovery time, 90% recovery time, and recovery percentage after 60 seconds. PVA: PMAA (2:1) The fastest 80% recovery time of the hydrogel of the embodiment is 1.2 seconds, the slower 90% recovery time is 17.4 seconds, and the lowest recovery rate after 60 seconds is 92.50%. This may be due to a small amount of PVA crystal domains hindering the reformation of hydrogen bonds during the strain-relaxation process. PVA: PMAA (1:2) The slowest 80% and 90% recovery times of the hydrogel of the example are 6 seconds and 18 seconds, respectively, but the highest recovery percentage after 60 seconds is 97.15%. This result can be explained by the amorphous nature of PMAA, because without crystal domains as an obstacle, the polymer chains can move and reorganize to a greater extent during the relaxation process. PVA: PMAA (1:1) hydrogel has the best overall performance, with a 90% recovery time of 9.6 seconds.

Table 3: 25% strain strain-relaxation curves of example hydrogels with different compositions. 2: 1 PVA: PMAA 1:1 PVA: PMAA 1:2 PVA: PMAA 80% recovery time (seconds) 1.20 1.80 6.00 90% recovery time (seconds) 17.40 9.60 18.00 Recovery after 60 seconds (%) 92.50 95.84 97.15 (4) Self-repair performance of the hydrogel of the embodiment

This test focuses on the self-healing ability of the PVA-PMAA example hydrogel. In this test, the PVA:PMAA example hydrogel (1:1) was cut into two parts, and then the fresh cut pieces were brought into contact under mild pressure. As shown in Figure 11, after placing the hydrogel under environmental conditions (the water content of the hydrogel is about 25%) for 4 days, it exhibits self-healing properties. The self-healing property of the hydrogel was tested under the environmental condition of 90% relative humidity from a nearby water bladder. The result not only recovers in a very fast time of 1, 2 and 5 minutes, but also restores the original elongation and similar Young's modulus (0.36MPa). The results show that the hydrogel of the present invention can quickly heal under higher relative humidity. (5) Recovery Potential of Example Hydrogel

It is well known that both PVA and PMAA are non-toxic, water-soluble, and biocompatible polymers. Therefore, the potential for recyclability and biodegradability are two important and attractive features of the example hydrogels. Although PVA-PMAA hydrogels have been cross-linked by EG, their covalent bonds consist of ether bonds and hydrolyzable ester bonds; therefore, water can be used to hydrolyze the hydrogels. The hydrolysis test of the hydrogel of the example is shown in FIG. 12. The degree of hydrolysis is defined as formula (2), where D _o is the initial weight of the hydrogel, and D _m is the weight of the hydrogel after hydrolysis. After being immersed in water for 24 hours, the degree of hydrolysis of the pure PVA hydrogel cross-linked by EG (as a comparative example) was only 5%. In comparison, the PVA:PMAA (1:1) hydrogel cross-linked for 3 hours (as an example) after immersing in water for 24 hours has a degree of hydrolysis of 70%, which means that 30% of the original hydrogel is still present. The PVA:PMAA (1:1) hydrogel whose crosslinking time is extended to 6 hours will reduce the degree of hydrolysis to 20%. According to the above results, the non-integral nature of the prepared hydrogel can be attributed to (1) some cross-linking points are hydrolyzable ester bonds; (2) moderate cross-linking temperature and shorter reaction time lead to lower Crosslink density. Compared to conventional elastomers, the dissolution of the example hydrogel in water is a unique advantage because it allows a low-energy recovery route. In the dispersed water phase, the polymer can be separated and reused, which is almost impossible for many cross-linked two-network hydrogels, elastomers, or hydrogel-elastomeric base layers. In order to prove this unique performance, this test further hydrolyzes the PVA: PMAA (1:1) (crosslinked for 3 hours) example hydrogel for 24 hours, and then evaporates all the water. After that, EG was added to dissolve the polymer and the solution was recast on the Teflon mold. As shown in Figure 13(a), the hydrogel can be successfully prepared again through the same manufacturing method. Fig. 13(b) shows the stress-strain curve of the hydrogel that has undergone one recovery and two recovery, respectively. After recasting, the hydrogel PVA:PMAA (1:1) still has sufficient stretchability and can be deformed by more than 300% strain. Young's modulus increased from 0.75 MPa to 1.52 MPa (recast -1) and 2.03 MPa (recast -2), respectively. The recovered hydrogel can still be stretched and can be reused for application. In short, the hydrogel of the present invention exhibits good stability and high mechanical properties under environmental conditions, and can be recycled and reused, which is superior to conventional hydrogel systems with high water content. In addition, the biodegradable elastomers (for example, poly(diol citrates) (PDC) and poly(glycerol sebacic acid), which are biodegradable with conventional technology, Compared with PGSA)), the self-repairing ability of the hydrogel of the present invention makes it have better mechanical reliability and durability (Table 4), and can be used for a long time.

Table 4: Comparison between the conventional technology and the present invention characteristic PDMS A typical hydrogel Biodegradable elastomer Embodiments of the present invention Young's modulus (MPa) ≈2.05 ≈0.12 ≈0.28 ≈0.75 Maximum elongation (%) ≈150 >1000 ≈450 >550 Air stability high low high high Self-repair no excellent no good Renewability low low high high (6) Preparation and characteristics of organic memory device of the embodiment

In this embodiment, a stretchable, recyclable and suitable hydrogel is applied to prepare a completely water-soluble and stretchable resistive organic memory device on the PVA:PMAA (1:1) embodiment hydrogel. Figure 14 shows the atomic force microscopy (AFM) phase and height images of the PVA:PMAA (1:1) hydrogel. The roughness of the hydrogel of the example is extremely low, less than 0.370 nm, indicating that its surface is sufficiently smooth. This is equivalent to the roughness of a silicon wafer or PDMS cast on a silicon wafer, making the hydrogel of the present invention a "green" alternative for preparing stretchable electronic devices. The AFM image also guarantees that the hydrogel of the present invention is not porous. As shown in Figure 15(a), the stretchable bottom and top electrode layers (22, 23) are made of polydioxyethylthiophene: poly(3,4-ethylenedioxythiophene) polystyrene sulfonate, PEDOT: PSS) and water-soluble polyurethane (polyurethane, PU) polymer blend composition, the ratio is 1:4 (ie 1:4 PEDOT: PSS/PU), which can ensure that the strain is not affected by strain up to 50% Electric current is used, and DNA is used as the memory layer 24. Figure 15(b) and (c) show the IV curve and residence time of the DNA organic memory device. The DNA membrane is initially at a very low current level (closed state), and then jumps to a high level (open state) _{at about 2.0 V (V c, ON ).} The on state cannot be restored to the off state, and remains unchanged during the subsequent forward, reverse, and negative voltage sweeps. The on-state remains unchanged even after the power off time exceeds 10,000 seconds, and at a read voltage of 1 V, the on/off current ratio is approximately 10 ⁴ . These results indicate that the DNA membrane shows excellent unipolar write-once-read-many-times (WORM) memory performance by using PEDOT:PSS/PU as the electrode. The nucleobase units such as purines and pyrimidines distributed in the DNA polymer can capture and transfer charges through the memory layer through an external electric field. The conduction process can be explained by the energy level of the electrode PEDOT:PSS. Generally, the energy levels of the Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) of natural DNA are about -5.30 and -1.08 eV, respectively. PEDOT: The PSS electrode has a HOMO energy level (-5.2 eV) similar to that of DNA, thereby reducing the energy barrier for hole injection. Conversely, since the energy gap between the LUMO energy level of DNA and the energy level of PEDOT:PSS (-3.2 eV) is relatively high, the possibility of electron injection from the electrode is low. Presumably, in DNA memory devices, the conduction process is mainly driven by hole injection. Similarly, WORM performance can be explained by the above reasons. Electron injection is not easy to perform in a negative scan, therefore, the open state cannot be eliminated through charge recombination.

In order to evaluate the feasibility of using DNA as an organic memory in stretchable electronic applications, the electrical switching performance and residence time of different memory devices were tested under strains of 10%, 30%, and 50%. The corresponding IV curve and residence time are shown in Figure 15(d) and (e). Organic memory exhibits similar WORM-type memory switch performance under different strain rates (10% to 50% strain). V _{c,ON is} maintained at about 2 V, slightly reduced to 1.9 V at 50% strain, the on/off current is maintained at ^{about 10 4 , and slightly reduced to 10 3} at 30% and 50% strain. Under various strain conditions, maintaining a low-writing voltage below 5 V proves the low power consumption advantage of this stretchable memory application. In each stretched state, the distinguishable on/off state under the read voltage of 1 V is retained, which means that the possibility of misreading data under different stretched states is very small. This is an extremely important factor in the field of wearable electronic devices, and the measurement accuracy under strain in the field of wearable electronic devices is very important. These results indicate that even if the organic memory device of the present invention is elongated, data data can be manipulated and programmed well. Next, we will further study the durability of the set open/close state in the stretched state. After the organic memory device of the embodiment was set to the on state, the durability test was performed on it. The device was stretched to 30% strain and then relaxed to its 0% strain length for 500 cycles. The 30% strain cycle was chosen because it is a typical upper strain limit for wearable electronic devices. As shown in Figure 15(f), the open state can maintain its high current conductivity, and only a slight degradation occurs after 500 cycles of stretching 30% strain. This means that the data storage of the device of the embodiment is quite long-lasting, because even under multiple cycles of extension and relaxation, it still maintains a high conduction state. Finally, a dissolution test was also performed on the organic memory device of the embodiment. As shown in Figure 16, the device can be completely hydrolyzed in water after 24 hours. These results indicate that the organic memory device based on the hydrogel of the present invention is not only stretchable, but also degradable in water. This test has successfully demonstrated an environmentally friendly stretchable resistive memory device manufacturing process.

In summary, the present invention provides a strong, air-stable and recyclable hydrogel that can be used as an environmentally friendly base layer for stretchable electronic applications. The hydrogel can be prepared by a simple polymer blend composed of two hydrophilic polymers, PVA and PMAA, with polyols as solvents and crosslinking agents. Unlike conventional hydrogels, the PVA-PMAA hydrogel provided by the present invention only absorbs sufficient water (25 wt%) from the surrounding atmosphere, and retains water through the hygroscopicity and strong hydrogen bonds of the polymer The molecule is more than one month. Compared with individual single components, the hydrogel uses water as a polymer chain transfer agent, so its overall tensile properties are significantly improved. The recoverability of the hybrid hydrogel (that is, the present invention) also surpasses the pure component hydrogel, and 1:1 is the best mixing ratio. More importantly, due to the large-scale hydrogen bonds and hydrolyzable ester bonds in the cross-linking mechanism, the polymer network can be dissolved in water, thereby making the gel recyclable and reusable. In addition, DNA is used as the active memory layer to prepare an air-stable and water-soluble stretchable resistive memory device based on the hydrogel (ie, the organic memory device of the present invention). The device exhibits a write once read many (write-once-read-many -times, WORM) type of performance, memory was ^104, the residence time exceeds ¹⁰⁵ seconds, the mechanical durability of more than 30% strain. The present invention provides a simple but developmental method for preparing a stretchable, air-stable and recyclable substrate layer, which can be easily integrated into the next generation of stretchable electronic devices. Example 2 : Conductive polymer hydrogel system, ultracapacitor device and preparation method thereof A. Experiment (1) Material

Polyvinyl alcohol (PVA) (degree of hydrolysis 87-90%, average molecular weight 30,000-70,000) and ethylene glycol (EG) (99.8% anhydrous) were purchased from Sigma-Aldrich (St. Louis, Missouri, USA). Polymethacrylic acid (PMAA) was purchased from Scientific Polymer Products (New York, USA). Clevios PH 1000-PEDOT: PSS was purchased from Heraeus (Hanau, Germany). Phosphoric acid (85.0-87.0%) was purchased from J.T. Baker Company (Pennsylvania, USA). All materials can be used without further purification. (2) Preparation Example Ion conductive hydrogel (polyelectrolyte based on hydrogel)

Prepare a polymer/EG solution with a mass ratio of PVA:PMAA=1:1 at a concentration of 200 mg/mL, and ^{stir at 60 o} C to obtain a transparent solution. Then add phosphoric acid at a concentration of 100 mg/mL. Then pour the mixed solution into a Teflon mold and ^{heat it at 150 o} C for 3 hours. (3) Preparation Example Electronically Conductive Hydrogel

The above-mentioned polymer/EG solution was mixed with PEDOT:PSS in different ratios to prepare the electronic conductive hydrogel of the embodiment, and the mass percentage concentration relative to PVA and PMAA was 100%, 11.8%, 6.3%, and 3.2%. Then slowly stir the polymer solution at 60 ^o C to obtain a viscous but uniform solution. Then pour the mixed solution into a Teflon mold and ^{heat it at 150 o} C for 3 hours. (4) The characteristics of the conductive polymer hydrogel system of the embodiment

Use a scanning electron microscope (SEM, JEOL JSM-6510) to observe the microscopic morphology of the stretched ion conductive hydrogel (ie ion conductive polymer hydrogel system, used as an electrolyte, also known as the electrolyte of the embodiment) of the example after stretching , And the morphology of the embodiment electronically conductive hydrogel (ie, the electronically conductive polymer hydrogel system, used as an electrode, also called the embodiment electrode). The stress-strain, stress-relaxation and loading-unloading curves were obtained by the DMA Q800 instrument (TA Instruments). For the stress-strain curve, an incremental force of 0.2 N/min to 18.0 N is used. The electrochemical properties of the ultracapacitor device of the embodiment were measured using CH instrument 627E at various scan rates and current densities ranging from 2 mV/s to 200 mV/s and 0.05 A/g to 0.5 A/g. For a fully stretchable ultracapacitor device, the area-based current is 0.05 mA/cm ² to 0.5 mA/cm ² .

(3) ， 其中S、t和R分別是電極表面積(cm² )、樣品厚度(cm)和半圓交點處的歐姆電阻。Use formula (3) to obtain ionic conductivity from electrochemical impedance spectroscopy (EIS) measurement

(3), where S, t, and R are the electrode surface area (cm ² ), the sample thickness (cm), and the ohmic resistance at the intersection of the semicircle, respectively.

(4) 其中ΔQ、w、I和s分別是在電位視窗ΔV上累積的電荷總量、一個電極中活性物質的質量、電流和電壓掃描速率。The average specific capacitance value of the ultracapacitor device is calculated according to the following formula (4):

(4) Where ΔQ, w, I, and s are the total amount of charge accumulated in the potential window ΔV, the mass of the active material in an electrode, the current and voltage scan rate, respectively.

(5)

(6) 其中∆t是放電時間。Energy density (E) and power density (P) can be calculated using the following equations (5) and (6):

(5)

(6) where ∆t is the discharge time.

The electrochemical impedance measurement system uses a frequency analyzer (Metrohm Autolab/PGSTAT30) under open circuit voltage (OCV), the frequency range is 100 kHz to 1 Hz, and the amplitude is 0.01 V. (5) Water content measurement

First put the example electrolyte and the example electrode (1×2 cm) in a vacuum chamber for 1 day at a pressure of 1×10 ^-3 Torr to remove the water absorbed during the curing process, and then place it under ambient conditions (25 ^o C. Relative humidity 60%). The definition of water content W (%) is shown in formula (1). (6) Preparation Example Supercapacitor Device

The preparation procedure of the ultracapacitor device is as follows: the electronic conductive hydrogel is cast on the stainless steel plate with different PEDOT:PSS ratios. Then the two electrodes is 0.8 cm ² area with the embodiment of the electrode and the electrolyte in Example embodiments stacked, hot pressed at 100 ^o C. For a fully stretchable ultracapacitor device, first, the electronically conductive hydrogel is cast on a silicon wafer. After curing, the gel (ie, electronically conductive hydrogel) is peeled from the silicon wafer to form a free-standing gel electrode. The gel electrode and gel electrolyte are used to prepare the fully stretchable ultracapacitor device in a similar hot pressing manner. B. Results (1) Preparation of PVA/PMAA-based ion and electronic conductive polymer hydrogel system

This embodiment uses a fast and environmentally friendly method to prepare the ion conductive polymer hydrogel system and the electronic conductive polymer hydrogel system. As shown in Figure 3(a), first dissolve PVA 32 and PMAA 33 in EG 34 solvent, and then dope with H ₃ PO ₄ 35 (gel: H ₃ PO ₄ = 1:1 (weight ratio)) to prepare Example electrolyte (ie ion conductive hydrogel 300) PVA 32/PMAA 33/H ₃ PO ₄ 35. For the electronically conductive hydrogel 400, as shown in Figure 3(b), drop the PEDOT:PSS 45 solution into PVA 42/PMAA 43/EG 44, and use PEDOT:PSS 45 to prepare concentrations of 3.2, 6.3, and 11.8 wt, respectively. % Of the final solution, named PPH3, PPH6 and PPH11, respectively. The entire polymer was dissolved in a mixed solvent (deionized water/EG) at a weight ratio of 2:3. Under the same experimental conditions, ion conductive hydrogels (used as electrolytes later) and electronically conductive hydrogels (used as electrodes later) were prepared through thermal crosslinking and film casting procedures combining PVA and PMAA polymer chains. Cast the prepared solution on a Teflon mold, and then use EG as a solvent and cross-linking agent ^{to cross-link at 150 o} C for 3 hours to form a double network of PVA and PMAA polymer blends. As shown in Figure 3(c), the left image shows the ion conductive hydrogel, and the right image shows the electronic conductive hydrogel. After ^{rehydration at 25 o} C for 24 hours under an environmental condition of 60% relative humidity, the two All conductive polymer hydrogel systems have high stretchability. The above process has the advantages of synergy as described below. First, the remaining hygroscopic EG can act as a plasticizer and increase the spacing between molecules and chain mobility, thereby enhancing water permeability and helping water absorption. Secondly, _{after mixing with H 3} PO ₄ , the free volume of PVA/PMAA increases, which increases the mobility of the PVA/PMAA chain, thereby improving the elasticity of the hydrogel electrolyte. (2) Physical properties of ion conductive hydrogel based on PVA/PMAA/H ₃ PO ₄

_{Fig. 17(a) shows the change of the water content of the PVA/PMAA/H 3} PO ₄ hydrogel (set as the ion conductive hydrogel of the example) with time under the environmental conditions of 25° C. and relative humidity of 60%. Note that the weight ratio of gel to H ₃ PO ₄ is optimized to 1:1 because _{excessive amount of H 3} PO ₄ in the gel will break the entanglement of the polymer chains and form a viscous jelly-like film. The water content is defined as formula (5). The water content absorbed into the PVA/PMAA/H ₃ PO ₄ hydrogel gradually increases with time and reaches an equilibrium value of about 22% after 24 hours. This result may be attributed to the hydrophilic polymer chain and the strong hydrogen bond formed between PVA/PMAA-water. The following further studies the influence of water content on the mechanical properties of ion conductive hydrogels, as shown in Figure 17(b). If the water content increases to 22%, the Young's modulus will decrease. The Young's modulus of the newly prepared ion conductive hydrogel and the wetted ion conductive hydrogel are 1.05 and 0.21 MPa, respectively. In addition, the elongation of the ion conductive hydrogel can be further increased from 150% to 475%. The changes in mechanical properties are similar to the PVA/PMAA blend hydrogel of Example 1. The water molecules absorbed in the gel can act as a chain plasticizer to enhance stretchability. Interestingly, as the water content of the PVA/PMAA/H ₃ PO ₄ hydrogel increases from almost dry to 22.3 wt%, the ionic conductivity increases from 5.0×10 ^-4 to 8.50×10 ^-3 S cm ^-1 , As shown in Figure 17(a). EIS showed that the volume resistance of the ion-conducting hydrogel decreased after moisture absorption (206 to 12 ohms), as shown in Figure 17(c). This is due to the increase of water molecules from the environment, thereby promoting ion conduction. Under various strains up to 100%, _{the conductivity of the PVA/PMAA/H 3} PO ₄ hydrogel remains quite constant, about 8.2×10 ^-3 S cm ^-1 (Figure 17(d), (e)). In addition, as shown in FIG. 17(f), the ion conductive hydrogel of the example has no significant mass change under strain, indicating that there is no water leakage during the stretching process. This further confirms its safety when used as an electrolyte in ultracapacitor devices. The results indicate that the ion conductive hydrogel of the present invention (which can be used as an electrolyte) has high stretchability, and the use of the hygroscopic hydrogel to capture moisture from the surrounding environment can achieve ion conductivity. It does not need to be immersed in the proton solution for a long time to rehydrate the hydrogel to prepare the ion conductive hydrogel. (3) Based on PVA/PMAA/PEDOT: Properties and morphology of PSS-based conductive hydrogel

Next, we use the _{same method as the PVA/PMAA/H 3} PO ₄ hydrogel to prepare PEDOT:PSS electronically conductive hydrogel, which has different PEDOT:PSS hydrogels (set as the example electronically conductive hydrogel) glue). Each combination of electronically conductive hydrogels is brittle, rigid, and non-stretchable before being wetted. Its maximum elongation is about 3-5%, and Young's modulus is 20-25 MPa. Interestingly, after 24 hours of water absorption, the electronically conductive hydrogel became soft and stretchable, as shown in Figure 18(a) (data of PPH6). According to the weight ratio of PEDOT:PSS, the mechanical properties (Young's modulus and fracture strain) of the PEDOT:PSS hydrogel before and after water absorption were compared, as shown in Fig. 18(b), (c) and Fig. 19. These electronically conductive hydrogels can be stretched to greater than 150% strain after absorbing water; in fact, with a PEDOT:PSS weight ratio of 3.2 wt%, stretching of up to 250% strain can be achieved. Obviously, the stretchability and mechanical strength of the electronically conductive hydrogel are related to the composition of PEDOT:PSS in the hydrogel. The Young's modulus of these electronically conductive hydrogels increased from 1.2 MPa (PPH3) to 7.2 MPa (PPH11), and as the weight ratio of PEDOT:PSS increased, the breaking strain tended to decrease.

The four-point probe method was used to calculate the electrical conductivity of the electronic conductive hydrogel of the embodiment by measuring the electrical resistance. Fig. 20(a) and Fig. 21 show the conductivity of the electronically conductive hydrogel of the embodiment before and after water absorption. The conductivity of all the prepared electronically conductive hydrogels before water absorption is about 0.1 S cm ^-1 , and this value tends to decrease with the change of the PEDOT:PSS composition in the electronically conductive hydrogels. As shown in the figure, the conductivity of the electronically conductive hydrogel increases after absorbing water. For example, as the water content of the electron conducting hydrogel from drying increased almost 22.3 wt%, electronically conductive hydrogel (PEDOT: PSS, 6.3 wt% ) conductivity increased from 0.6 S 3.2 S cm cm ^{-1 - 1} . Compared with the conductive hydrogel of the prior art, the example PEDOT:PSS hydrogel exhibits relatively higher electrical conductivity, as shown in Table 5. The higher conductivity observed can be explained as follows. First, the use of organic compounds with multiple hydroxyl groups (such as EG) as the solvent and secondary dopant in the hydrogel solution can induce phase-segregated PSS-rich domains. ), so the highly conductive PEDOT-PSS grains may fuse together to form a three-dimensional conductive network. Inside the hydrogel, the coiled and stacked PEDOT:PSS chains form a polymer conductive path. Secondly, as shown in Figure 20(b), the increase in the molecular weight of water from the environment in the hydrogel promotes ion conduction. Before PPH6 absorbed water, its resistance and impedance did not change significantly in the frequency range of 0.1 Hz to 1M Hz. In addition, even at lower frequencies, its capacitive reactance only changes very little. This shows the typical impedance behavior of electrical conductors. Conversely, after PPH6 absorbs water, when the frequency decreases, its capacitive reactance is greatly increased. The observed capacitance characteristics are due to ion migration. Similar characteristics have been observed for other hydrogel-based conductors. Therefore, the electronically conductive hydrogel has the characteristics of a comprehensive ionic and electronically conductive hydrogel. 22 is shown in FIG. 25 ^o C, relative humidity of 60% under ambient conditions, PPH6 quality and conductance versus time. In 30 days, these two values remained fairly constant and did not drop significantly. PPH6 not only has a high conductivity comparable to CPHs of the prior art, but also has a high degree of air stability. The literature points out that the use of PEDOT:PSS/acrylamide organogel can improve the stability of the hydrogel. The main component of organogel is EG, and its vapor pressure is lower than water. Therefore, the organogel can maintain its stretchability for a long time. However, due to the substitution of EG organic solvent for water in the hydrogel to inhibit ion conduction, its conductivity is only 0.1 S cm ^-1 . In addition to air stability, electrochemical stability is another important issue for hydrogel electrodes. As shown in Fig. 20(c), the current in the milliampere range flows irregularly in the voltage range of -2 to 2 V, which is represented as non-ohmic conduction. However, no bubble formation was observed where the hydrogel and the electrode were in contact. This means that the measured current is not an induced current. Therefore, the electronically conductive hydrogel can be used as the current collector of the ultracapacitor device because it does not have any electrochemical reaction in a wide potential range. The electrochemical stability of the electronically conductive hydrogel of the embodiment will be further discussed in the supercapacitor device of the embodiment. Before stretching until electrical failure occurred, the electrical resistance of the electronically conductive hydrogel of the example was measured in situ. Fig. 20(d) shows the normalized resistance change and the tensile strain of the example electronically conductive hydrogels with different PEDOT:PSS compositions. By adjusting the composition of PEDOT:PSS to less than 6.3 wt%, there is almost no change in electrical resistance when stretched to 100% strain. Even under tensile deformation, the internal percolation path of PEDOT:PSS can remain intact inside the PVA/PMAA hydrogel. The hydrogen bonds inside the PVA and PMAA networks can act as a buffer and relieve the stress of applying strain, thereby preventing the electronically conductive hydrogel from rupturing. Figure 23 (a) and (b) show _{SEM images of pure PVA/PMAA/H 3} PO ₄ (ie the ion conductive hydrogel of the example) and PPH6 (ie the electronic conductive hydrogel of the example). The pure PVA/PMAA hydrogel presents a smooth surface. On the contrary, due to the phase separation between the PEDOT:PSS and the hydrogel, it can be observed that the electronically conductive hydrogel has a relatively rough surface (Figure 23(b)). This special form may facilitate the penetration of the electrolyte and make the electrolyte ions easily accessible to the active material. Compared with conventional conductive hydrogels (Table 5), the present invention provides a new way to prepare hydrogels with high conductivity and stretchability in a fast and environmentally friendly method. By precisely controlling the composition and water absorption process of PEDOT:PSS, PPH6 can have good stretchability and moderate electrical conductivity.

Table 5: Comparison of conductive hydrogel/organogel systems of the prior art material method Stretch of Conductivity (S/cm) PEGMA/PEDOT/PAA Thermal free radical polymerization (APS) 80% 3.4 Known technology PPY/Agarose Oxidizer (CuCl ₂ ) 40% 0.5 Known technology CD/PAAm/PANi Thermal free radical polymerization (APS) 300% 0.39 Known technology PAM/PEDOT Thermal free radical polymerization (APS) 350% 0.01 Known technology PVA/PMAA/PEDOT (this invention) Condensation (Crosslinker EG) 120% 3.1 Embodiments of the invention (4) Electrochemical performance of stretchable ultracapacitor device based on electronically conductive hydrogel

Next, an essentially stretchable ultracapacitor device based on the conductive polymer hydrogel system of the present invention is prepared. In view of the fact that the symmetrical structure of the ultracapacitor device is collector-electrode material-electrolyte, this embodiment proposes that PEDOT: PSS electronically conductive hydrogel can be used as both the current collector and electrode material, because PEDOT: PSS electronically conductive hydrogel is wet After having high conductivity. Combining the current collector and the electrode material into a single layer body can prevent structural deformation of the ultracapacitor device and reduce the electrochemical performance of the device. The aforementioned structural deformation such as: displacement and delamination under large deformation. Before preparing an essentially stretchable ultracapacitor device, this example uses stainless steel as the current collector and PVA/PMAA/H ₃ PO ₄ hydrogel as the solid electrolyte. The electrochemical properties of the electronically conductive hydrogel are first studied. . Table 6 summarizes the mass load of PEDOT:PSS in each electrode. Figure 24 (a) and (b) compare the cyclic voltammetry (CV) and galvanostatic charge/discharge of the example ultracapacitor devices with different amounts of PEDOT:PSS electronically conductive hydrogels , GCD) curve, the relevant data are summarized in Table 7. Figure 24(a) shows the CV of various electronically conductive hydrogel electrodes at a scan rate of 10 mV/s. CV refers to the typical rectangular shape and represents the ideal capacitance response. Compared with pure PEDOT:PSS (3.6 Fg ^{-1 at 10 mVs -1} ), the supercapacitor device of the embodiment has better capacitance performance after being doped with PVA/PMAA hydrogel. Therefore, the specific capacitance values of PPH11 and PPH6 are increased to 8.4 Fg ^-1 and 13.2 Fg ^{-1, respectively} . PVA/PMAA hydrogel can help ions get close to the active material far away from the electrode surface, so as to make full use of the electronic conductive hydrogel on the current collector. However, as the content of PEDOT:PSS decreases to 3.2 wt%, its specific capacitance decreases to 7.3 Fg ^-1 . Use EIS to understand the electrochemical performance of a large number of electrode materials and/or the interface between the electrode and the electrolyte in the ultracapacitor device. In the low frequency region, the impedance characteristic is related to the charge transfer resistance (R _ct ), while in the high frequency region, the low intercept of the Z real axis is related to the low equivalent series resistance (series resistance, R _s ). Including the internal resistance of the electrode and the ohmic resistance of the electrolyte. The above values are obtained through a fitting circuit (Warburg's model). As the content of PEDOT:PSS decreased from 11.8 wt% to 6.3 wt% and 3.2 wt%, the R _s plus R _{ct of the ultracapacitor} device increased from 505 ohms to 585 ohms and 984 ohms, respectively (Figure 24(c)). The charge transfer efficiency can be improved by increasing the amount of PEDOT:PSS in the hydrogel. Generally, PPH6 shows the best capacitance performance when the CV curve is most saturated, and its corresponding GCD curve also shows the longest discharge time when the ^{current density is 0.1 Ag -1.} It is worth noting that the highest specific capacitance PPH6 of 10 mVs ^-1 is 13.2 Fg ^-1, 0.1 mVs ^-1 is 12.2 Fg ^-1, which is the use of PEDOT: PSS as the super capacitor electrode material of the present invention The device is quite. Figure 24(d) shows CV curves of PPH6 electrode-based ultracapacitor devices collected at different scan rates. When the scan rate is ^{increased from 5 mVs -1} to 200 mVs ^-1 , all the curves show a basically similar and symmetrical shape, indicating that the device has good capacitance performance. The typical triangular shape of the GCD curve at different current densities (Figure 24(e)) further shows that based on the inclined curve, the ultracapacitor device has excellent capacitance performance. The generated surface capacitance is equivalent to the surface capacitance calculated by the CV integration method. As shown in Figure 25, when the current densities are 0.1 ^{, 0.2, 0.3, 0.4, and 0.5 Ag -1} , the specific capacitance values obtained are 12.18, 10.59, 9.34, 8.36, and 7.57 Fg ^{-1, respectively} . The PPH6 electrode has good cycle stability, and its capacitance is only reduced by 5% after 2000 cycles (Figure 24(f)), which is an ideal value for conductive polymer electrodes. For example, the capacitance retention rate of PEDOT:PSS after 2000 cycles is only 54%. This means that the stability of the electronically conductive hydrogel is enhanced due to the use of the hydrogel. Obviously, the introduction of PVA/PMAA hydrogel into PEDOT:PSS can cause synergistic effect, thereby preventing the possible expansion and contraction of active PEDOT:PSS during charging and discharging. Generally, as the hydrogel increases, the charge-discharge stability of the ultracapacitor device gradually increases, and the optimal value is PPH6.

Table 6: PEDOT of the supercapacitor device of the embodiment: mass load and electrode area of the PSS. PEDOT: PSS content (%) Area (cm ² ) Electrode weight (mg) PEDOT: PSS mass load (mg/cm ² ) 100 0.8 0.7 0.88 11.8 0.8 2.7 0.40 6.3 0.8 3.4 0.27 3.2 0.8 7.6 0.30

Table 7: Comparison of PVA/PMAA/PEODT:PSS hydrogels with different compositions. PEDOT: PSS content (%) Specific capacitance at 10 mV/s (F/g) Specific capacitance at 0.1 A/g (F/g) Capacitance maintenance rate after 2000 cycles (%) R _ct ( ohm ) 100 3.6 3.0 54 152 11.8 (PPH11) 8.4 7.7 84 505 6.3 (PPH6) 13.2 12.2 95 585 3.2 (PPH3) 7.3 8.4 32 984

As shown in the previous section, PPH6 not only exhibits good mechanical properties, but also exhibits high electrical conductivity (from 0.55 to 3.2 S cm ^-1 ) after being wetted with water. It is an ideal stretchable substrate layer, which can serve as a current collector and a mechanical support to realize a fully stretchable supercapacitor (FSSC). In addition, PPH6 has the best electrochemical performance in three different PEDOT:PSS compositions. Therefore, as far as PPH6 has relatively high electrical conductivity and good mechanical properties, PPH6 is used as the stretchable conductive base layer of the stretchable electrode in the following tests. As shown in Fig. 3(d) and Fig. 26(a), by _{sandwiching the PVA/PMAA/H 3} PO ₄ hydrogel as the solid electrolyte 52 between two identical PPH6 electrodes 51, then proceeding at 100 ^o C Hot press to assemble FSSC. The electrochemical performance of the FSSC device when no strain is applied at different scan rates is shown in Figure 27(a). As the scan rate ^{increases from 10 mVs -1} , all curves exhibit a substantially similar and symmetrical shape. It can be observed that the FSSC device exhibits an ideal rectangular CV shape and has a fast current response when the voltage is reversed. The capacitance of the ultracapacitor device calculated from the CV curve is shown in Figure 28(a), ^{and the value at 10 mV s -1} is 7.38 mF cm ^-2 . Figure 27(b) shows GCD curves at various charge/discharge current densities ^{from 0.1 to 0.5 mA cm -2.} As shown in the figure, the capacitance calculated from the GCD curve is similar to the result obtained from the CV curve (Figure 28(b)). The obtained FSSC showed a ^{reasonable energy density of 0.65 μW h cm -2} and a power density of 0.17 mW cm ^-2 . In addition, as shown in Figure 29, the PPH6-based ultracapacitor device exhibited a capacitance retention rate of 82% after 2000 cycles. During charging and discharging, the Coulomb efficiency is maintained at approximately 100%. Therefore, in this process, there will be no side reaction to the capacitance, and the capacitance comes from the PEDOT:PSS electrode. This test further demonstrates the FSSC after connecting 4 supercapacitor devices in series to increase the output voltage to 3.2 V, which is enough to light up the LED bulb (Figure 30).

In order to study the mechanical properties of the ultracapacitor device, first measure the CV curve of the FSSC under different bending ratios, and analyze the capacitance performance in the potential range of 0 to 0.8 V at a scan rate of 10 mV/s. Figure 26(b) shows that the CV curve of the FSSC is almost at the same position. This means that even at 180 ^° , it still has stable pseudo-capacitance behavior during shape deformation and exhibits excellent flexibility. FSSC maintains its electrochemical performance when stretched from 0% to 100% at a constant stretching rate of 1 mm/min (Figure 26(c)). After 500 and 1000 cycles of 30% strain, the capacitance retention rate of FSSC was 96% and 91%, respectively (Figure 26(d)). Note that the cyclic tensile test is performed at a crosshead speed of 10 mm/min at room temperature. The ultracapacitor device exhibits excellent durability to repeated stretch-relaxation tests. The shape of the CV curve remains largely unchanged, except that the slopes of the curve are 0 and 0.8 V, respectively. After 1000 cycles, the scanning direction will change and the steepness will be slightly reduced. The decrease in slope can be attributed to the increase in equivalent series resistance after 1000 stretching cycles (Figure 31). This experiment also studied the cycle stability of FSSC after stretching for 1000 cycles, as shown in Figure 26(e). For all ultracapacitor devices, the specific capacitance value remains in good condition after 2000 cycles. All these results indicate that the PEDOT:PSS electronically conductive hydrogel-based FSSC prepared by the environmentally friendly method developed by the present invention has both mechanical stability and electrochemical stability.

In summary, the present invention has developed a fast and environmentally friendly method to prepare a conductive polymer hydrogel system with high electrical conductivity and excellent stretchability. By precisely controlling the PEDOT:PSS content and the water wetting process, the electronically conductive hydrogel with 6.3 wt% PEDOT:PSS (ie, PPH6 in Example 2) exhibits good stretchability and moderate electrical conductivity. The electronically conductive hydrogel prepared by the invention can be used as a current collector and as an electrode material to prepare a stretchable ultracapacitor device. The ultracapacitor device of the present invention can prevent the inherent problems of delamination, displacement and strain-accommodating engineering in the traditional laminated stretchable ultracapacitor device. The prepared ultracapacitor device exhibits a capacitance of 7.38 mF cm ^{-2 at 10 mV s -1} , which is equivalent to an ultracapacitor device using PEDOT:PSS as the electrode material. It provides a large amount of deformation (up to 100% strain) without affecting electrochemical performance. More importantly, the electrochemical performance of the ultracapacitor device is well preserved even after 1000 times of 30% tensile strain. The present invention not only creates an effective platform for stretchable ultracapacitor devices of modern flexible electronic devices and skin-like wearable devices, but also realizes environmental protection methods for environmental sustainability.

Above, the present invention is explained in more detail through preferred exemplary embodiments. Although exemplary embodiments have been disclosed herein, it should be understood that other variations are also possible. Such changes should not be regarded as departing from the spirit and scope of the exemplary embodiments of the present application, and all modifications obvious to those skilled in the art are still included in the scope of the appended application.

100: hydrogel 11: polymer network 111: polyvinyl alcohol 112: polymethacrylic acid 113: crosslinking agent 200: organic memory device 21: base layer 22: top electrode layer 23: bottom electrode layer 24: memory Body layer 300: ion conductive hydrogel 31: hydrogel solution 32: polyvinyl alcohol 33: polymethacrylic acid 34: crosslinking agent/ethylene glycol 35: conductive material/H ₃ PO ₄ 400: electronically conductive hydrogel 41: Hydrogel solution 42: Polyvinyl alcohol 43: Polymethacrylic acid 44: Crosslinking agent/ethylene glycol 45: Conductive material/PEDOT: PSS 500: Ultracapacitor device 51: Electrode 52: Electrolyte M: Moisture

Figure 1 shows a preferred embodiment of the hydrogel of the present invention, in which (a) is a schematic diagram of preparing PVA: PMAA hydrogel; (b) is a schematic diagram of three covalent bonds in the hydrogel; and (c) is Schematic diagram of the cross-linking mechanism.

Figure 2 is a digital photograph of a preferred embodiment of preparing PVA and PMAA hydrogels in water at a concentration of 100 mg/mL. After mixing, gelation occurs spontaneously, and a large amount of hydrogel precipitates from the water.

Figure 3 is a schematic diagram of a preferred embodiment of the present invention, in which (a) is a method for manufacturing a conductive polymer hydrogel system (ion conductive hydrogel), and (b) is a conductive polymer hydrogel system (electronic conductive (C) is a digital photograph of the conductive polymer hydrogel system in a stretched state, and (d) is a supercapacitor device based on the conductive polymer hydrogel system of the present invention.

Figure 4 shows the FTIR spectra of (a) hydrogels with different mass ratios and (b) PVA:PMAA (1:1) hydrogels with different crosslinking times and temperatures. (c) PVA as a function of crosslinking temperature and duration: the change of the ratio of A1700/A2930, A1178/A2930 and A3320/A2930 of PMAA (1:1) hydrogel.

Fig. 5 is a thermal analysis diagram of (a) TGA and (b) DTG of PVA, PMAA and hydrogel, wherein the hydrogel has different weight ratios of PVA relative to PMAA cast in EG.

Figure 6 is a graph showing the moisture absorption of PVA, PMAA and hydrogel blends cast in EG and water.

Figure 7 is an XRD pattern of PVA, PMAA and hydrogel, where the hydrogel has a different weight ratio of PVA relative to PMAA cast in EG.

Figure 8 is a DSC thermogram of PVA, PMAA and hydrogel, where the hydrogel has a different weight ratio of PVA relative to PMAA cast in EG.

Figure 9 shows the residence time of PVA:PMAA=1:1 sample water content. In this example, three samples with different initial weights (170, 240, and 280 mg) were prepared to evaluate water retention.

Figure 10 shows: (a) digital photos of hydrogel PVA: PMAA (1:1) at different strain rates (strain rates are 0%, 100% and 200% from left to right); (b) contains The influence of water content on PVA: the stress-strain curve of PMAA (1:1) hydrogel; (c) the stress-strain curve of PVA, PMAA and hydrogel blends cast in EG; (d) PVA: PMAA (1:1) loading-unloading cycle of hydrogel; and (e) strain-relaxation curve of hydrogel blend under 25% strain.

Figure 11 shows the stress-strain curves of PVA:PMAA (1:1) hydrogel before and after recovery.

Figure 12 shows the solubility test of pure PVA and PVA:PMAA (1:1) hydrogels with different crosslinking times. The test was performed with deionized water.

Figure 13 shows: (a) Recovery through PVA: PMAA (1:1) hydrogel dissolved in deionized water; and (b) Stress of recovered PVA: PMAA (1:1) hydrogel- Strain curve.

Figure 14 shows the AFM morphology and phase imaging of PVA:PMAA (1:1) hydrogels in (a) 25 μm ² and (b) 100 μm ^{2 regions.}

Figure 15 shows: (a) a schematic diagram of a stretchable DNA memory device; (b) IV curve and (c) residence time of a DNA memory device prepared on a 1:1 hydrogel; the DNA memory device is in (D) IV curve and (e) residence time (read at 1 V) collected under 0%, 10%, 30% and 50% strain; and (f) after 500 times of 30% strain and relaxation, it can be The open state of the stretched DNA resistance device is maintained.

Figure 16 shows the dissolution test of the DNA device in 60°C deionized water. The substrate can be hydrolyzed in deionized water after 24 hours. After 24 hours, DNA and PEDOT:PSS were completely dissolved in deionized water.

_{Figure 17 shows: (a) the hygroscopicity and conductivity of PVA/PMAA/H 3} PO ₄ hydrogel at 25°C and 60% relative humidity over time; (b) PVA/PMAA/H ₃ PO ₄ hydrogel stress-strain curve before and after water absorption; (c) _{12 hours and 24 hours impedance spectra of PVA/PMAA/H 3} PO ₄ hydrogel before and after water absorption; (d) PVA/PMAA at room temperature /H ₃ PO ₄ hydrogel impedance spectra under different strains; (e) at room temperature, _{the ionic conductivity of PVA/PMAA/H 3} PO ₄ hydrogel under different strains; and (f) in the room Under temperature, the quality of PVA/PMAA/H ₃ PO ₄ hydrogel changes under different strains.

Figure 18 shows: (a) the stress-strain curve of the electronically conductive hydrogel of the present invention (PEDOT: PSS 6.3 wt%) (PPH6) before and after water absorption; (b) PEDOT: PSS with different compositions and water absorption effects Comparison of fracture strain of glue; and (c) Comparison of Young's modulus of PEDOT:PSS hydrogels with different compositions and water absorption effects.

Figure 19 shows the stress-strain curves of electronically conductive hydrogels with different PEDOT:PSS compositions after absorbing water.

Figure 20 shows: (a) the relationship between the weight ratio and conductivity change of the PEDOT:PSS hydrogel as a function of the electronic conductivity after water absorption; (b) the electronically conductive hydrogel of the present invention before and after water absorption (PEDOT: PSS 6.3 wt%) (PPH6) impedance curve; (c) PEDOT: I (current)-V (voltage) sweep frequency measurement of PSS hydrogel; and (d) standardized resistance during hydrogel stretching Change graph.

Figure 21 shows graphs of (a) water content change and (b) conductivity change of the electronically conductive hydrogel of the present invention over time under environmental conditions of 25°C and relative humidity of 60%.

Figure 22 shows a graph of the long-term stability of the electronically conductive hydrogel (PEDOT: PSS 6.3 wt.%) PPH6 of the present invention, and the data is recorded under environmental conditions of 25°C and relative humidity of 60%.

Figure 23 shows FE-SEM images of (a) PVA/PMAA/H ₃ PO ₄ and (b) the electronically conductive hydrogel of the present invention (PEDOT: PSS 6.3 wt%) (PPH6).

Figure 24 shows: (a) the electrochemical performance CV curve of the ultracapacitor device based on the PEDOT: PSS content change conductive polymer hydrogel system at a scan rate of 10 mV/s; (b) the charge and discharge current is 0.1 mA The GCD curve of the ultracapacitor device; (c) the impedance curve of the ultracapacitor device based on the electronically conductive hydrogel of the present invention with various PEDOT:PSS contents; (d) the CV curve of different scanning using PPH6 electrode and (e) ) GCD curves at different current densities; and (f) Capacitance retention and Coulomb efficiency of the ultracapacitor device based on the electronically conductive hydrogel (PEDOT: PSS 6.3 wt%) (PPH6) of the present invention.

Figure 25 shows (a) the rate performance of the electronically conductive hydrogel of the present invention in terms of specific capacitance (F/g). The specific capacitance is the current passing through the entire voltage window by cyclic voltammetry (CVs) The density is integrated to calculate, and (b) the specific capacitance value graph calculated according to the GCD curve.

Figure 26 shows (a) the SEM image of the stretchable ultracapacitor device; (b) the CV curve of the ultracapacitor device under different bending states; (c) the CV curve of the ultracapacitor device when strain is applied; (d) The CV curve of the ultracapacitor device under the condition of applying 30% strain and different stretching cycles; and (e) After applying 30% strain for 1000 times, the electronically conductive hydrogel based on the present invention (PEDOT: PSS 6.3 wt%) (PPH6) Capacitance maintenance rate and Coulomb efficiency of the ultracapacitor device.

Figure 27 shows (a) the CV curve of the FSSC of the electronically conductive hydrogel of the present invention (PEDOT: PSS 6.3 wt.%) PPH6 with different scan rates; and (b) the GCD curve.

Figure 28 shows (a) the rate performance of a stretchable ultracapacitor device based on the electronically conductive hydrogel of the present invention in terms of area capacitance (mF/cm ² ). The area capacitance is measured by cyclic voltammetry (CVs) Calculate by integrating the current density passing through the entire voltage window; and (b) the graph of the specific capacitance value calculated according to the GCD curve.

Figure 29 is a schematic diagram of the capacitance retention and coulombic efficiency of the FSSC based on the electronically conductive hydrogel (PEDOT: PSS 6.3 wt.%) (PPH6) of the present invention as the electrode material and current collector.

Figure 30 shows a digital photograph of an LED bulb powered by four supercapacitor devices connected in series.

Figure 31 shows the impedance curves of the FSSC based on the electronically conductive hydrogel of the present invention (PEDOT: PSS 6.3 wt.%) (PPH6) before and after stretching 1000 times under 30% strain.

no.

11: polymer network

111: polyvinyl alcohol

112: Polymethacrylic acid

113: Crosslinking agent

M: Moisture

Claims (21)

A hydrogel comprising: a polymer network, which is a polymer network of poly(vinyl alcohol) (PVA) and poly(methacrylic acid) (PMAA); wherein the polymerization The material network includes a cross-linking agent to cross-link polyvinyl alcohol and polymethacrylic acid, and the cross-linking agent is ethylene glycol (EG). The hydrogel according to claim 1, wherein the mass ratio of the PVA: the PMAA ranges from 2:1 to 1:2. The hydrogel according to claim 2, wherein the mass ratio of the PVA: the PMAA is 1:1. A method for preparing the hydrogel according to any one of claims 1 to 3, the steps of which include: a. dissolving polymers PVA and PMAA in an organic compound having a plurality of hydroxyl groups to form a polymer solution; b . Heating the polymer solution; and c. Injecting the polymer solution into a mold and heating for cross-linking reaction. An organic memory device comprising: a bottom electrode layer; a top electrode layer; and a base layer, which is arranged under the bottom electrode layer, and the base layer includes the hydrogel according to any one of claims 1 to 3 plastic; and a memory layer, which is disposed between the bottom line electrode layer and the top electrode layer, the memory layer comprises a deoxy RNA (deoxyribonucleic acid, DNA). The organic memory device according to claim 5, wherein the bottom electrode layer and the top electrode layer comprise a conductive polymer, and the conductive polymer is selected from polyacetylene-based polymers and poly(p-phenylene) Polyphenylenevinylene-based polymer, polyaniline (PANi), polypyrrole-based polymer, polythiophene-based polymer, polythiophene-based polymer (polythiophenevinylene-based polymer) and polydioxyethylthiophene: poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT: PSS). The organic memory device according to claim 6, wherein the bottom electrode layer and the top electrode layer comprise a polymer blend of PEDOT:PSS and water-soluble polyurethane (PU). The organic memory device according to claim 6, wherein the bottom electrode layer and the top electrode layer comprise a polymer blend of PEDOT:PSS and water-soluble polyurethane, and the polymer blend includes PEDOT:PSS and water-soluble The ratio between the polyurethane is 1:4. A conductive polymer hydrogel system, comprising: the hydrogel according to any one of claims 1 to 3; and a conductive material distributed in the polymer network. The conductive polymer hydrogel system according to claim 9, wherein the conductive material is an acid, a base or a salt, and the conductive polymer hydrogel system forms an ion conductive hydrogel. The conductive polymer hydrogel system according to claim 10, wherein the acid is selected from the group consisting of sulfuric acid, phosphoric acid and perchloric acid. The conductive polymer hydrogel system according to claim 10, wherein the alkali is potassium hydroxide (KOH). The conductive polymer hydrogel system according to claim 10, wherein the salt is selected from the group consisting of lithium chloride (LiCl), lithium perchlorate (LiClO ₄ ) and potassium chloride (KCl). The conductive polymer hydrogel system according to claim 9, wherein the conductive material is selected from the group consisting of polyacetylene-based polymers, poly(p-styrene-based polymers, polyaniline, polypyrrol-based polymers, and polythiophene-based polymers) , Polythiophene vinylidene polymer and PEDOT: PSS group, and the conductive polymer hydrogel system forms an electronic conductive hydrogel. The conductive polymer hydrogel system according to claim 9, wherein the ion conductive hydrogel is an electrolyte, and the electrolyte is disposed in an ultracapacitor device. A supercapacitor device, comprising: at least two electrodes; and an electrolyte, which is arranged between the electrodes; wherein the electrode and the electrolyte are made of the conductive polymer hydrogel system according to claim 9, the The conductive material of the electrode is an electronic conductive material, and the conductive material of the electrolyte is an ion conductive material. The supercapacitor device according to claim 16, wherein the electronically conductive material is a conductive polymer, and the conductive polymer is selected from the group consisting of polyacetylene-based polymer, poly(p-styrene-based polymer), polyaniline, and polypyrrole-based polymer Compounds, polythiophene-based polymers, polythiophene vinylidene polymers and PEDOT: a group consisting of PSS. The ultracapacitor device according to claim 17, wherein the electronically conductive material is PEDOT:PSS. The ultracapacitor device according to claim 16, wherein the ion conductive material is an acid, a base or a salt. The ultracapacitor device according to claim 19, wherein the acid is selected from the group consisting of sulfuric acid, phosphoric acid and perchloric acid; the base is KOH; and the salt is selected from the group consisting of _{LiCl, LiClO 4 and KCl} group. A method for preparing the conductive polymer hydrogel system according to claim 9, the steps of which include: a. dissolving the polymers PVA and PMAA in an organic compound having a plurality of hydroxyl groups to form a polymer solution, and heating The polymer solution; b. The conductive material is added to the polymer solution and mixed; and c. The aforementioned mixed solution is injected into a mold and heated for cross-linking.

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