KR20230159666A - Extremotolerant glycerogels, their fabrication process and application - Google Patents

Abstract

The present invention relates to glycerogel and a method for producing the same, and more specifically, to an extremely resistant glycerogel that exhibits excellent long-term stability at -50 - 80 ° C without sacrificing the structural and functional properties of the hydrogel, a method for producing the same, and It relates to application products that include this.

Description

Extremely tolerant glycerogels, manufacturing method thereof, and application products containing the same {Extremotolerant glycerogels, their fabrication process and application}

The present invention relates to glycerogel and a method for producing the same, and more specifically, to an extremely resistant glycerogel that exhibits excellent long-term stability at -50 - 80 ° C without sacrificing the structural and functional properties of the hydrogel, a method for producing the same, and It relates to application products that include this.

Recently, gels, a class of semi-solid materials formed by cross-linked 3D polymer networks swollen in specific solvents, have received considerable attention due to their applications in biomedicine, flexible electronics, energy storage, sensors/actuators, and soft robotics. They exhibit a variety of functions that no other solid or liquid substance can exhibit alone. Due to their highly solvated polymer network, gels exhibit inherently tissue-like structures, biocompatibility, cell compatibility, and numerous biological functions. At the same time, their solid- and liquid-like properties allow them to be tailored to achieve specific electrical, thermal, actuation, shape transformation, and stimulus response properties.

Hydrogels are formed by a network of hydrophilic polymers swollen in water and are widely used due to their biocompatibility and vast scope for biomedical applications. To overcome the mechanical weaknesses of conventional hydrogels, several mechanically strong hydrogels have been developed, such as double-network, ionic/covalent, nanocomposite, polyvalent, dynamically cross-linked, and hydrophobic/hydrophilic. However, their short lifespan in air limits their applications, especially in harsh environmental conditions. Recently, several methods have been developed to improve the air stability of hydrogels.

For example, double hydrophobic coated hydrogels have long-term air stability. Various glycol/aqueous organic hydrogels with excellent floating ability at subzero temperatures have been reported. A photosensitive gel based on metal coordination was developed in a glycerol/water mixture. These gels work at sub-zero temperatures. Gels prepared from ethylene glycol/water mixture had good anion conductivity. However, none of the previously mentioned gel materials can be used in extreme temperatures (cold and hot). Therefore, it is difficult to establish a broad concept for the development of gel materials with various cross-linking/reinforcement mechanisms and gel functions that are durable at both cryogenic and high temperatures.

Domestic Patent Registration No. 10-2166153

Based on numerous research results, the present inventors completed the present invention by developing a technology that can produce a wide range of extremely resistant glycerogels (GG) from pre-designed hydrogels.

Therefore, the purpose of the present invention is to provide a new class of ultra-resistant glycerogels with a wide range of customized properties and functions prepared from pre-designed hydrogels without sacrificing the structural and functional properties of the original hydrogels, and a method for their preparation.

Another object of the present invention is to adjust the elasticity, electrical conductivity, and ionic conductivity of extreme-resistant glycerogel as needed and to develop next-generation extreme energy storage devices, sensors or actuators, soft robots, etc. using the adjusted glycerogel as a soft material. It provides various application products including:

The object of the present invention is not limited to the object mentioned above, and even if not explicitly mentioned, the object of the invention that can be recognized by a person of ordinary skill in the art from the description of the detailed description of the invention described later may also naturally be included. .

In order to achieve the purpose of the present invention described above, first, the present invention is a glycerogel in which the water molecules of the hydrogel are replaced with glycerol, and the weight change is ±10 wt for 7 days under temperature conditions ranging from -50℃ to 80℃. We provide an extremely resistant glycerogel that exhibits properties maintained within %.

In a preferred embodiment, depending on the type of hydrogel, the glycerogel is selected from the group consisting of stretchability, stiffness, strength, modulus, and work of extension. One or more mechanical properties are changed.

In a preferred embodiment, when the hydrogel is a polyacrylamide (PAAm) hydrogel, the glycerogel is PAAm glycerogel (GG), and the PAAm GG has an elasticity of 1200% or more, a modulus of 0.09 ± 0.003 MPa, and a modulus of 0.22 It has a strength of ±0.02 MPa.

In a preferred embodiment, when the hydrogel is a polyvinyl alcohol (PVA) hydrogel, the glycerogel is a PVA glycerogel, and the PVA GG has a stiffness of 8.9 ± 0.2 MPa, a strength of 8.5 ± 0.01 MPa, and a strength of 49.9 ± 49.9 ± 0.2 MPa. It has a strain energy (work of extension) of 0.4 MJ m ^-3 .

In a preferred embodiment, if the hydrogel is a poly(acrylamide-co-acrylic acid)/iron(III)(P(AAm-co-AAc)/Fe ³⁺ ) hydrogel, the glycerogel is P(AAm- co- AAc)/Fe ³⁺ glycerogel, and the P(AAm-co-AAc)/Fe ³⁺ GG has a rigidity of 1.6 ± 0.1 MPa, a strength of 7.1 ± 0.3 MPa, and a strength of 23.5 ± 4.6 MJ m ^-3 . It has strain energy (work of extension).

In a preferred embodiment, if the hydrogel is a cellulose hydrogel, the glycerogel is a cellulose glycerogel, and the cellulose GG has a stiffness of 9.4 ± 0.9 MPa, a strength of 2.9 ± 0.1 MPa, and an elasticity of less than 100%. .

In a preferred embodiment, the fracture toughness of the glycerogel in the solid state ranges from 1581 J m ^-2 to 19,627 J m ^-2 .

In a preferred embodiment, the ionic conductivity of the glycerogel in the liquid state is proportional to temperature.

In a preferred embodiment, the ionic conductivity of the glycerogel is 0.003±0.0003 S m ^-1 at -20°C, 0.021±0.006 S m ^-1 at 25°C, and 0.11±0.03 S m ^-1 at 80°C.

In a preferred embodiment, the glycerogel has self-welding ability and a bonding strength of 0.77 MPa or more.

In addition, the present invention includes the steps of preparing a hydrogel; Preparing a glycerogel precursor through solvent exchange in which water molecules in the hydrogel are replaced with glycerol; and an annealing step of heat-treating the glycerogel precursor and then cooling it to room temperature.

In a preferred embodiment, the solvent exchange is a rapid substitution reaction performed by immersing the hydrogel in a single concentration glycerol solution for several hours at 50°C to 100°C depending on the characteristics of the hydrogel, and the glycerol concentration is 0% to 100% at room temperature. It is performed by one of the slow substitution reactions carried out by sequentially immersing the reaction in a number of gradually increasing glycerol solutions for tens of hours.

In a preferred embodiment, a rapid substitution reaction is performed when the hydrogel is a water-swelling hydrogel, and the water-swelling hydrogel is a polyacrylamide hydrogel.

In a preferred embodiment, in the step of preparing the glycerogel precursor, when the solvent exchange is performed through the rapid substitution reaction to produce the glycerogel precursor, the glycerogel is prepared at room temperature to ensure complete exchange of glycerol and water. It further includes a stabilization step of immersing the precursor in a glycerol solution for several tens of hours.

In a preferred embodiment, the heat treatment in the annealing step is performed dry or wet at 100°C to 200°C for several hours.

In a preferred embodiment, if the prepared hydrogel is a polyacrylamide (PAAm) hydrogel, the step of preparing the glycerogel precursor involves heating the PAAm hydrogel at 50°C to 70°C for 90 to 180 minutes at 100 °C. Preparing a PAAm glycerogel precursor by immersing it in % glycerol solution; And a stabilization step of immersing the PAAm glycerogel precursor in a 100% glycerol solution at room temperature for 24 to 48 hours, and the annealing step is performed by placing the PAAm glycerogel precursor in a sealed reactor and heating at 100°C. It is performed by dry heat treatment at ±1 for 2 to 4 hours and then slowly cooled to 24 to 26°C.

In a preferred embodiment, if the prepared hydrogel is a polyvinyl alcohol (PVA) hydrogel, the step of preparing the glycerogel precursor is performed by preparing the PVA hydrogel at room temperature with a glycerol concentration of 25% ± 1 and 50%, respectively. It is performed by sequentially immersing in a glycerol solution with a ±1 concentration for 11 to 13 hours and in a glycerol solution with a glycerol concentration of 75% ± 1 and 100% ± 1 for 23 to 25 hours, and the annealing step is This is carried out by placing the PVA glycerogel precursor in a sealed reactor and heat-treating it in a dry manner at 110°C to 130°C for 5 to 7 hours, followed by gradual cooling to 24 to 26°C.

In a preferred embodiment, if the prepared hydrogel is a poly(acrylamide-co-acrylic acid)/iron(III)(P(AAm-co-AAc)/Fe ³⁺ ) hydrogel, the glycerogel precursor The manufacturing step is to place the P(AAm-co-AAc)/Fe ³⁺ hydrogel in a glycerol solution with a glycerol concentration of 0% ± 1 and 25% ± 1, respectively, at room temperature for 11 to 13 hours and at a glycerol concentration of 50% ± 1. It is carried out including the step of sequentially immersing in % ± 1 and 100% ± 1 glycerol solutions for 23 to 25 hours, and the annealing step is performed by immersing the P(AAm-co-AAc)/Fe ³⁺ glycerogel precursor. This is carried out by placing it in a glycerol bath and wet heat treatment at 110°C to 130°C for 90 to 150 minutes, followed by gradual cooling to 24 to 26°C.

In a preferred embodiment, if the prepared hydrogel is a cellulose hydrogel, the step of preparing the glycerogel precursor is performed by preparing the P(AAm-co-AAc)/Fe ³⁺ hydrogel at room temperature so that the glycerol concentration is 0. It includes the step of sequentially immersing in glycerol solutions with %±1 and 25%±1 glycerol concentrations for 11 to 13 hours, and in glycerol solutions with glycerol concentrations of 50%±1 and 100%±1 for 23 to 25 hours. The annealing step is performed by placing the cellulose glycerogel precursor in a sealed reactor, dry-treating it at 110°C to 130°C for 300 to 400 minutes, and then slowly cooling to 24°C to 26°C.

In addition, the present invention relates to any of the above-mentioned ultra-resistant glycerogels or the ultra-resistant glycerogel prepared by any of the above-described production methods; And it provides an electrically conductive glycerogel comprising a metal pattern formed on the surface of the glycerogel.

In a preferred embodiment, the electrically conductive glycerogel stretches and recovers at -50 to 80°C with the gel intact.

In addition, the present invention provides an application product containing any of the above-described extreme-resistant glycerogels or any of the above-described extreme-resistant glycerogels prepared by any of the above-mentioned production methods.

In a preferred embodiment, the application is a flexible energy storage device, sensor, actuator or robot.

In a preferred embodiment, if the energy storage device is a super capacitor, the capacitance is 2.2-6 mF cm ^-2 at -20 to 80°C.

According to the present invention described above, a new type of ultra-resistant glycerogel with a wide range of customized properties and functions prepared from a pre-designed hydrogel without sacrificing the structural and functional properties of the original hydrogel and a method for preparing the same can be provided. .

In addition, according to the present invention, the elasticity, electrical conductivity, and ionic conductivity of the extreme resistant glycerogel are adjusted as needed, and the adjusted glycerogel is applied as a soft material to create a next-generation extreme energy storage device, sensor or actuator, soft robot, etc. We can provide various application products including:

Therefore, the present invention utilizes currently available hydrogels with a wide range of functions and properties to meet the extreme resistance required in rigorous next-generation applications, thereby providing a variety of extreme resistance, flexibility, and stability for bio, electrical/electronic, and soft robotic applications. Elastic devices can be manufactured.

These technical effects of the present invention are not limited to the scope mentioned above, and even if not explicitly mentioned, the effects of the invention that can be recognized by a person of ordinary skill in the art from the description of the specific contents for implementing the invention described later. Of course it is included.

Figure 1 schematically illustrates a strategy that mimics the survival behavior of bear beetles to design the ultra-resistant glycerogel (GG) of the present invention. Here, a shows that the bear beetle can transform into a “tun state” under extreme conditions by preserving its integrated structure that can withstand a variety of harsh environmental challenges, and b shows an extremely multifunctional animal inspired by the tun formation of the bear beetle. GG shows that various polymers were designed by integrating them with a green solvent (glycerol), c shows that the water initially incorporated into the predesigned functional hydrogel was sequentially replaced with glycerol to minimize damage to the integrated structure of the gel. , dry annealing the as-prepared GG released the undesired residual stresses and obtained the final GG with a preserved polymer structure similar to the tun formation of the bear beetle, but in contrast, direct solvent exchange resulted in a phase-separated rigid structure inside the gel network. It shows that it caused.
Figure 2 shows the tensile stress strain curves of PAAm gel prepared using various polyol solvents and propylene glycol gel showing a stable three-dimensional shape ((ad) glycerol, ethylene glycol, propylene glycol, and tripropylene glycol as solvents, respectively. PAAm (3-0.05) gel prepared using: Only the gel formed with propylene glycol showed a stable three-dimensional shape (e) Tensile stress-strain curve of propylene glycol gel).
Figure 3 shows tensile stress-strain curves of (a) PVA, (b) PAAm, and (c) P(AAm-co-AAc)/Fe ³⁺ hydrogels and their corresponding GGs. These were fabricated by directly equilibrating the hydrogel in 100% glycerol.
Figure 4 illustrates the various monomers/polymers and crosslinkers used in the GG design of the present invention. Here, this versatility of the present invention facilitates the design of various multifunctional GGs.
Figure 5 shows characterizing the extreme resistance ability of GG according to various embodiments of the present invention. a is the result of observing the effects of low (-50℃), ambient (25℃) and high (80℃) temperatures on the developed GG, and b is after 7 days of incubation at -50, 25℃ and 80℃. is the weight fraction of GG, and c to f are representative tensile stress-strain curves of PAAm, PVA, P(AAm-co-AAc)/Fe ³⁺ and cellulose GG, respectively (tensile tests were performed on the raw samples and the results were stored at -50 , compared with the results of samples incubated at 25 and 80 °C for 7 days), and g and h show the results of demonstrating the elasticity of PAAm and PVA GG after incubation at -50 °C and 80 °C for 7 days, respectively.
Figure 6 is a graph showing the change in weight fraction of GG according to various embodiments of the present invention while exposed to air at -50, 25, and 80°C for 7 days, where a to d are PAAm, P(AAm-co, respectively) -AAc)/Fe ³⁺ , PVA and cellulose GG.
Figure 7 is a comparative graph of PAAm GG samples according to various embodiments of the present invention before and after exposure to air at -50, 25, and 80 ° C. for 7 days, where a is Young's modulus, b is tensile strength, and c is strain energy ( It means work of extension.
Figure 8 is a comparative graph of PVA GG samples according to various embodiments of the present invention before and after exposure to air at -50, 25, and 80 ° C. for 7 days, where a is Young's modulus, b is tensile strength, and c is strain energy. it means.
Figure 9 is a comparative graph of P(AAm- co -AAc)/Fe ³⁺ GG samples according to various embodiments of the present invention before and after exposure to air at -50, 25, and 80°C for 7 days, where a is the Young's modulus. , b means tensile strength, and c means strain energy.
Figure 10 is a comparative graph of cellulose GG samples according to various embodiments of the present invention before and after exposure to air at -50, 25, and 80°C for 7 days, where a is Young's modulus, b is tensile strength, and c is strain energy. it means.
Figure 11 is a photograph showing that when the PAAm hydrogel was exposed to air on top of a hot plate set at 150°C for 10 min, the weight decreased by 64% and the gel completely lost its elasticity due to the almost complete loss of networked water.
Figure 12 is a photograph demonstrating the extreme heat resistance of PAAm GG according to various embodiments of the present invention. Here, after exposing the samples to air on a hotplate set at 150°C for 10 minutes, only 1.5% of their weight was lost and the samples showed remarkable elasticity without breaking.
Figure 13 shows the results of evaluating the fracture toughness, hysteresis, elasticity, and plasticity of GG according to various embodiments of the present invention. a shows a demonstration of tensile testing of notched samples for fracture energy measurements, b shows force versus displacement curves for notched and unnotched samples of PVA GG (the critical point at which cracks start to propagate through the notched samples). The displacement (Lc) (detected by video analysis) was identified as an open circle, the fracture energy was determined by dividing the cross-sectional area of the sample by the work done to stretch the unnotched sample to Lc (filled area), and c is The determined fracture energies of different GGs are shown, and d to g represent the repeated tensile load-load curves with different waiting times for PAAm GG, PVA GG, P(AAm-co-AAc)/Fe ³⁺ GG, and cellulose GG, respectively. It is shown, and h represents the repeated tensile load-load curve of PVA GG in which the strain is periodically increased up to 100% until the breaking point.
Figure 14 is a graph comparing the fracture energy of PAAm hydrogel and PAAm GG.
Figure 15 shows the results of testing the repeated tensile load-load curves of soft PVA GG made from a PVA precursor solution at different intervals, where a is 5 wt% and b is a 3 wt% precursor solution.
Figure 16 shows the cyclic tensile load-load curve of PVA GG tested continuously for 50 cycles, with the initial and 50th cycles indicated. The gel was fully recovered 20 minutes after completing 50 consecutive cycles.
In Figure 17, a shows the cyclic tensile load-load curve of P(AAm-co-AAc)/Fe ³⁺ GG tested at different intervals, and b shows P(AAm-co-AAc) tested continuously for 50 cycles. )/Fe ³⁺ GG cyclic tensile load-load curve is shown. The initial and 50th cycles were indicated, and the gel fully recovered almost 20 minutes after completion of 50 consecutive cycles.
Figure 18 is a repeated tensile load-load curve in which 100% strain is periodically increased up to the breaking point in soft PVA GG made from a PVA precursor solution, where a is 5 wt% and b uses a 3 wt% precursor solution.
Figure 19 is the ratio of cumulative strain to applied strain plotted against applied strain for PVA GG fabricated with various concentrations of precursor solutions, with data derived from Figures 13h and 18.
Figures 20a and 20b show GG-based self-adhesion, where a is a demonstration of the self-adhesion process of cellulose GG and b shows a lap shear test to determine the shear adhesion and strength of the bonded cellulose GG.
Figure 21 shows the results of a lap shear test to determine the shear adhesion and strength of bonded PVA GG prepared with 5 wt% PVA precursor solution.
Figure 22 shows the design specifications of a fractal type mask.
Figure 23a-c is an illustration and photo of silver-patterned PVA GG fabricated by a mask-controlled ion sputtering process, d shows LED switching by patterned PVA GG connected to a 9V battery through a 200 ohm resistor, and Figure 23b shows e to g are results demonstrating the elasticity of patterned PVA GG at -50, 25, and 80°C, respectively.
Figure 24a shows the fabrication and characterization of a flexible PVA GG electrolyte-based supercapacitor, and Figure 24b shows the ionic conductivity of the PVA GG electrolyte at various temperatures.
Figure 25 is a graph of the results of measuring the cyclic voltammogram of a flexible PVA GG electrolyte-based supercapacitor, where a shows the cyclic voltammogram (CV) of the PVA GG electrolyte-based supercapacitor device recorded at 25°C and various scan rates. and b shows the comparison between the calculated areal capacitance of the device at different scan rates.
Figure 26 is a graph measuring the charge and discharge results of the flexible PVA GG electrolyte-based supercapacitor. a shows the charge and discharge curve of the PVA GG electrolyte-based supercapacitor device at 25°C with various currents applied, and b shows the charge and discharge curve of the PVA GG electrolyte-based supercapacitor device at different currents. It shows a comparison between the calculated area capacitance of .
Figure 27a shows the CV profile recorded at a scan rate of 1 mV s ^-1 , and Figure 27b shows the calculated area capacitance of the supercapacitor device measured at different temperatures.
Figure 28 is a graph comparing the area capacitance of the supercapacitor of the present invention with various recently reported high-performance supercapacitors made of various electrode/electrolyte materials.

The terms used in the present invention are merely used to describe specific embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, terms such as “comprise” or “have” are intended to designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the description of the invention, but are intended to indicate the presence of one or more other It should be understood that this does not exclude in advance the presence or addition of features, numbers, steps, operations, components, parts, or combinations thereof.

Terms such as first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, a first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component without departing from the scope of the present invention.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and unless clearly defined in the present invention, should not be interpreted in an idealized or excessively formal sense. No.

When interpreting a component, it is interpreted to include the margin of error even if there is no separate explicit description. In particular, when terms of degree such as "about", "substantially", etc. are used, they may be interpreted as being used at or close to that value when manufacturing and material tolerances inherent in the stated meaning are presented. .

In the case of a description of a temporal relationship, for example, if a temporal relationship is described as ‘after’, ‘after’, ‘after’, ‘before’, etc., ‘immediately’ or ‘directly’ Even non-consecutive cases are included unless ' is used.

Hereinafter, the technical configuration of the present invention will be described in detail with reference to the attached drawings and preferred embodiments.

However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Like reference numerals used to describe the invention throughout the specification represent like elements.

The technical features of the present invention are a new type of ultra-resistant glycerogel with a wide range of customized properties and functions manufactured from a pre-designed hydrogel without sacrificing the structural and functional properties of the original hydrogel, a manufacturing method thereof, and application products containing the same. It is in At this time, a wide range of customized properties and functions include elasticity, plasticity, hysteresis, self-healing, thermal shock absorption ability (150℃) and long-term stability over a very wide temperature range (-50℃ to 80℃), as well as a wide range of stiffness, strength, and Includes elasticity and toughness. However, none of the previously known glycerogels could be used at both extreme temperatures (cold and hot).

Therefore, the extremely resistant glycerogel of the present invention maintains uniform polymer distribution inside the hydrogel and is a glycerogel in which the water molecules of the hydrogel are replaced with glycerol, and can be maintained for 7 days under temperature conditions ranging from -50°C to 80°C. It shows the characteristic that the weight change is maintained within ±10 wt% during the period.

In other words, the extreme-resistant glycerogel of the present invention is a new type of gel material designed using glycerol, a low-molecular-weight polyol that is inspired by the tun formation of Tardigrades and can maintain its polymer structure, function, and properties even under extreme conditions. Because it is. As shown in Figure 1a, bear beetles are the most resilient life forms on Earth and can survive in extreme conditions such as extremely low and high temperature pressure, dry weather, and intense radiation. Under harsh environmental conditions, bear bugs undergo a structural transition into a form known as the "tun state" by slowly squeezing out most of the unbound free water while simultaneously producing cytoprotective molecules such as sugars (including trehalose and glycerol) and proteins. These molecules constitute a network of intra- and intermolecular bonds between themselves and biomolecules and cells to prevent irreversible damage when exposed to harsh conditions. Additionally, as shown in Figure 1b, glycerol is a bio-derived green solvent that is rich in hydroxyl groups and forms a facile H-bond network within itself and with various hydrophilic polymers. Glycerol exhibits excellent supercooling down to the glass transition temperature (-83°C), very low vapor pressure (1 mmHg at 125°C) and very high boiling temperature (290°C). Pure glycerol was adopted as an ultra-protective molecule for the hydrogel network in the present invention because it functions similarly to sugars and proteins in protecting the tun state.

Therefore, the extreme resistance glycerogel of the present invention is composed of the stretchability, stiffness, strength, modulus, and work of extension of the glycerogel depending on the type of hydrogel. One or more mechanical properties selected from the group may be varied.

As an embodiment, if the hydrogel is a polyacrylamide (PAAm) hydrogel, the glycerogel is PAAm glycerogel (GG), and the PAAm GG has an elasticity of 1200% or more, a modulus of 0.09 ± 0.003 MPa, and a modulus of 0.22 ± 0.02. It has a strength of MPa.

As another embodiment, if the hydrogel is a polyvinyl alcohol (PVA) hydrogel, the glycerogel is a PVA glycerogel, and the PVA GG has a stiffness of 8.9 ± 0.2 MPa, a strength of 8.5 ± 0.01 MPa, and 49.9 ± 0.4 MJ. It has a strain energy (work of extension) of m ^-3 .

As another embodiment, the hydrogel is poly(acrylamide-co-acrylic acid)/iron(III)(P(AAm-co-AAc)/Fe ³⁺ ) hydrogel. The glycerogel is P(AAm-co- AAc)/Fe ³⁺ glycerogel, and the P(AAm-co-AAc)/Fe ³⁺ GG has a stiffness of 1.6±0.1 MPa, a strength of 7.1±0.3 MPa, and a strain energy of 23.5±4.6 MJ m ^-3 . (work of extension).

As another embodiment, if the hydrogel is a cellulose hydrogel, the glycerogel is a cellulose glycerogel, and the cellulose GG has a stiffness of 9.4 ± 0.9 MPa, a strength of 2.9 ± 0.1 MPa, and an elasticity of less than 100%.

The glycerogel of the present invention may have a fracture toughness of 1581 J m ^-2 to 19,627 J m ^-2 in the solid state, and ionic conductivity in the liquid state is proportional to temperature. As an example, the ionic conductivity of glycerogel may be 0.003±0.0003 S m ^-1 at -20°C, 0.021±0.006 S m ^-1 at 25°C, and 0.11±0.03 S m ^-1 at 80°C.

In addition, the glycerogel of the present invention has self-welding ability, and the bonding strength may be 0.77 MPa or more.

The glycerogel of the present invention, which has the above-described properties, builds an extremely protected network through intra- and intermolecular H-bonding with various hydrophilic polymers through a wide temperature-tolerant glycerol and creates a microenvironment suitable for various cross-linking structures and reinforcement mechanisms. This can open the way to various functionalization. Additionally, soft polymers (PAAm), which lack energy dissipation mechanisms and have a loose covalent cross-linked structure, offer very high elasticity and fast self-recovery.

As can be seen from the experimental examples described below, the very high toughness, elasticity and strength of PVA GG are achieved due to efficient energy dissipation promoted by the high density of sacrificial H-bonds in the soft PVA polymer, where the plastic deformation in PVA GG is irreversibly large. Hysteresis occurred. The efficient and reversible energy dissipation of dual cross-linked (covalent and ionic coordination) GG produced a balance of softness, strength and toughness with low hysteresis and excellent self-healing properties. H-bond-based GG prepared from hard natural polymers such as cellulose had lower elasticity than soft PVA GG, but showed superior stiffness, strength, and toughness due to efficient energy dissipation. Rigid natural polymers can be used to fabricate GGs with various biomimetic superstructures. GG according to the present invention showed excellent stability at -50 to 80°C regardless of polymer and cross-linking structure. Long-term stability over such a wide temperature range has not been achieved for soft materials to date. Additionally, the high thermal shock absorption capacity at 150°C confirms the extreme durability of the protection network even under harsh conditions. Furthermore, the physically cross-linked GG exhibited excellent self-adhesion capabilities conferred by ion-induced structural reorganization, which provides significant advantages for designing a variety of extreme tolerance devices with complex 3D structures.

Therefore, according to the present invention, GG with various extraordinary functions can be developed by rationally integrating various functional materials without being limited to the above-described configuration.

Next, the method for producing ultra-resistant glycerogel of the present invention includes preparing a hydrogel; Preparing a glycerogel precursor through solvent exchange in which water molecules in the hydrogel are replaced with glycerol; And it may include an annealing step of heat-treating the glycerogel precursor and then cooling it to room temperature.

As shown in Figure 2, it was confirmed that most polyol solvents are not suitable for producing gels with excellent structural integrity because their high viscosity and polymerization-induced phase separation reduce the degree of polymerization and prevent the formation of 3D gel structures. In contrast, numerous hydrogels with various functions have been reported, and in the preparation step of the hydrogel of the present invention, various pre-designed functional hydrogels were used as basic materials.

The present invention utilizes the high water-glycerol affinity due to H-bond formation, as shown in Figure 1c, to produce an extremely resistant glycerogel, a process that is very similar to the structural transition of a bear bug by water in the gel network. It was replaced with glycerol without disturbing the polymer structure and function of the original hydrogel. In other words, the water contained in the pre-designed functional hydrogel prepared in the hydrogel preparation step is sequentially replaced with glycerol in the glycerogel precursor manufacturing step to minimize damage to the integrated structure of the gel. After preparing GG, the as-prepared GG precursor was annealed to release unwanted residual stress and obtain final GG with a preserved polymer structure similar to the tun formation of the bear bug. On the other hand, Figure 1c also shows, in contrast, that direct solvent exchange resulted in a phase-separated rigid structure inside the gel network.

More specifically, for most hydrogels, direct exchange of the original solvent with a viscous organic solvent causes unwanted phase separation and polymer aggregation due to rapid swelling of the gel due to the high osmotic pressure of the viscous solvent or changes in polymer-solvent affinity. Occurs. As shown in Figure 1 c, when a typical water-equilibrium poly(vinyl alcohol) (PVA) hydrogel is soaked in glycerol, the gel releases most of the water and shrinks to a weight fraction (W) of 38%. Therefore, direct solvent exchange, as shown in Figure 3, produces a hard and brittle plastic type gel. The stepwise slow exchange of the original solvent can prevent the structural collapse of water-stable hydrogels, as shown in Figure 1 c, and thus prevent or greatly reduce gel shrinkage. For water-swelling hydrogels (e.g., polyacrylamide (PAAm) hydrogels), rapid solvent exchange (instead of slow exchange) at high temperatures can prevent structural collapse due to swelling. Once solvent exchange is complete, unwanted residual stresses in the gel network can be released by thermal annealing of the gel.

Therefore, the ultra-resistant glycerogel production method of the present invention is a simple method that enables the production of a wide range of ultra-resistant glycerogels (GG) from pre-designed hydrogels without sacrificing the structural and functional properties of the original hydrogel, as described later. It involves a two-step process, that is, manufacturing a glycerogel precursor and an annealing step.

Here, the step of preparing the glycerogel precursor is a step in which solvent exchange is performed in which water molecules in the prepared hydrogel are replaced with glycerol. Solvent exchange is performed in a single concentration glycerol solution at 50°C to 100°C depending on the characteristics of the hydrogel. It can be carried out by either a fast substitution reaction, which is carried out by immersion for several hours, or a slow substitution reaction, which is carried out by sequentially immersing for several tens of hours in a plurality of glycerol solutions in which the glycerol concentration is gradually increased from 0% to 100% at room temperature. You can.

The annealing step is a step performed to relieve unwanted residual stress on the gel network and uniformly distribute the polymer and cross-linked structure by heat treating the glycerogel precursor. The heat treatment for this can be done in a dry or wet manner at 100°C to 200°C. This is done for a period of time, and if the heat treatment temperature is less than 100℃, the desired degree of residual stress relief may not be obtained, and if it exceeds 200℃, there is a problem that thermal damage to the material itself may occur. Here, whether the annealing step is performed dry or wet may be determined depending on the type of hydrogel.

In one embodiment, a rapid substitution reaction is performed if the hydrogel is a water-swelling hydrogel. The water-swelling hydrogel is not limited as long as it is a polymer with very high hydrophilicity and absorbency, but in an embodiment of the present invention, the water-swelling hydrogel is poly. Acrylamide hydrogel was used.

In particular, when solvent exchange is performed through a rapid substitution reaction to produce a glycerogel precursor, the step of preparing the glycerogel precursor is to place the glycerogel precursor in a glycerol solution at room temperature for several tens of hours to ensure complete exchange of glycerol and water. It may be performed by further including a stabilization step of immersion.

As another embodiment, if the produced hydrogel is a polyacrylamide (PAAm) hydrogel, the step of preparing the glycerogel precursor involves soaking the PAAm hydrogel in 100% glycerol solution at 50°C to 70°C for 90 to 180 minutes. Preparing a PAAm glycerogel precursor by immersing in; And a stabilization step of immersing the PAAm glycerogel precursor in a 100% glycerol solution at room temperature for 24 to 48 hours, and the annealing step is performed by placing the PAAm glycerogel precursor in a sealed reactor and heating at 100°C. It can be performed by dry heat treatment at ±1 for 2 to 4 hours and then slowly cooling to 24 to 26°C.

As another embodiment, if the produced hydrogel is a polyvinyl alcohol (PVA) hydrogel, the step of preparing the glycerogel precursor is performed by preparing the PVA hydrogel at room temperature with a glycerol concentration of 25% ± 1 and 50% ± 1, respectively. It is performed by sequentially immersing the PVA in a phosphorus glycerol solution for 11 to 13 hours and in a glycerol solution with a glycerol concentration of 75% ± 1 and 100% ± 1 for 23 to 25 hours. This can be performed by placing the glycerogel precursor in a sealed reactor and heat-treating it dry at 110°C to 130°C for 5 to 7 hours, followed by gradual cooling to 24 to 26°C.

As another embodiment, if the prepared hydrogel is a poly(acrylamide-co-acrylic acid)/iron(III)(P(AAm-co-AAc)/Fe ³⁺ ) hydrogel, the glycerogel precursor The manufacturing step is to place the P(AAm-co-AAc)/Fe ³⁺ hydrogel in a glycerol solution with a glycerol concentration of 0% ± 1 and 25% ± 1, respectively, at room temperature for 11 to 13 hours and at a glycerol concentration of 50% ± 1. It is carried out including the step of sequentially immersing in % ± 1 and 100% ± 1 glycerol solutions for 23 to 25 hours, and the annealing step is performed by immersing the P(AAm-co-AAc)/Fe ³⁺ glycerogel precursor. It can be performed by putting it in a glycerol bath and heat treating it in a wet manner at 110°C to 130°C for 90 to 150 minutes, then slowly cooling to 24 to 26°C.

As another embodiment, if the prepared hydrogel is a cellulose hydrogel, the step of preparing the glycerogel precursor is performed by preparing the P(AAm-co-AAc)/Fe ³⁺ hydrogel at room temperature, respectively, so that the glycerol concentration is 0. It includes the step of sequentially immersing in glycerol solutions with %±1 and 25%±1 glycerol concentrations for 11 to 13 hours, and in glycerol solutions with glycerol concentrations of 50%±1 and 100%±1 for 23 to 25 hours. The annealing step may be performed by placing the cellulose glycerogel precursor in a sealed reactor, dry-treating it at 110°C to 130°C for 300 to 400 minutes, and then gradually cooling to 24°C to 26°C.

Next, the electrically conductive glycerogel of the present invention is an ultra-resistant glycerogel having the above-described composition; And it may include a metal pattern formed on the surface of the glycerogel. At this time, the electrically conductive glycerogel has the property of stretching and recovering without damaging the gel at -50 to 80°C. As an example, stretchable electrically conductive GG was produced by ion sputtering a fractal-shaped silver pattern on the surface of the GG. In general, high-speed ion sputtering generates a lot of heat around the sputtering area, making metal deposition on soft materials difficult. The structural and thermal stability of GG and the atomic-scale polymer-silver-particle adhesion showed the elasticity of hybrid GG at -50~80℃ without interfacial damage.

Next, the application product of the present invention includes an ultra-resistant glycerogel having the above-described configuration, and may be any of a flexible energy storage device, sensor, actuator or robot. As described above, the ultra-resistant glycerogel of the present invention can be applied to various industrial fields due to its excellent elasticity, electrical conductivity, and ionic conductivity. In particular, it can contribute to the development of soft materials for next-generation extreme energy storage devices, sensors, actuators, or robots. .

As an embodiment, if the energy storage device is a supercapacitor, the capacitance is 2.2-6mF cm ^-2 at -20 to 80℃, and as can be seen in the experimental examples described later, it operates similarly to several recently reported high-performance supercapacitors. The supercapacitor according to the present invention has excellent capacitance, can operate in a wide temperature range, and has flexibility, making its usability very high.

Example 1

Polyacrylamide glycerogel (PAAm GG) was prepared as follows.

1. Steps to prepare hydrogel

PAAm hydrogel was prepared through free radical polymerization as follows. Precursor solution containing 3M acrylamide (AAm) monomer, 0.05 mol% (based on monomer concentration) N,N'-methylenebisacrylamide (MBAA) crosslinker, and 0.1 mol% (based on monomer concentration) using deionized water. APS initiator was prepared. The solution was poured into a rectangular mold prepared by sandwiching a 3 mm thick silicone rubber gasket between two flat plastic plates. Afterwards, the mold was incubated at 60°C for 8 hours to perform polymerization to prepare the PAAm hydrogel.

2. Steps for producing glycerogel precursor

The prepared PAAm hydrogel was removed from the mold and immersed in pre-incubated glycerol at 60°C for 2 h to rapidly exchange water with glycerol. Afterwards, the obtained gel was immersed in glycerol at 25°C for 3 days to ensure complete exchange of glycerol and water to prepare a glycerogel (GG) precursor.

3. Annealing step

2.6mm)를 얻었으며, 이를 추가 특성화에 사용했다.The prepared GG precursor was dry annealed in a sealed glass vial at 100 °C for 3 h and then slowly cooled to 25 °C to form the desired PAAm GG (thickness

2.6 mm), which was used for further characterization.

Example 2

Poly(vinyl alcohol) glycerogel (PVA GG) was prepared as follows.

1. Steps to prepare hydrogel

PVA hydrogel was prepared by freeze-thawing as follows with some modifications. The PVA solution was prepared by dissolving PVA powder in a DMSO/water (75:25, w/w) mixture at 140°C overnight with continuous stirring. DMSO/water mixtures are known to produce fine crystals of PVA chains at sub-zero temperatures. Unless otherwise specified, a 10 wt.% PVA precursor solution was used to fabricate pristine PVA GG. The solution was inserted into a 3 mm thick rectangular plastic mold (prepared by sandwiching a silicone rubber gasket between two plastic plates). Afterwards, the mold containing the polymer solution was incubated at -50°C for 1 day and then thawed at 25°C for 12 hours. The formed gel was removed from the mold and soaked in water for 3 days. Water-equilibrated PVA hydrogel was obtained by repeatedly replacing the water.

2. Steps for producing glycerogel precursor

The obtained PVA hydrogel was sequentially immersed in glycerol aqueous solutions with 25%, 50%, 75%, and 100% glycerol content for 12 hours, 12 hours, 24 hours, and 24 hours, respectively, to obtain PVA GG precursor.

3. Annealing step

The prepared GG precursor was annealed in a sealed glass vial at 120°C for 6 h and then slowly cooled to 25°C to obtain the desired PVA GG (thickness). 1.8 mm), which was used for further characterization.

Example 3

Poly(acrylamide-co-acrylic acid)/iron(III) glycerogel (P(AAm-co-AAc)/Fe ³⁺ GG) was prepared as follows.

1. Steps to prepare hydrogel

P(AAm-co-AAc) hydrogel was prepared by free radical copolymerization of AAm and AAc as follows. Precursor solutions containing 3 M AAm and 0.6 M AAc were prepared in water in the presence of 0.1 mol% MBAA and 0.1 mol% APS (relative to the total amount of monomers) as crosslinker and initiator, respectively. The solution was inserted into a 2 mm thick plastic mold (prepared by sandwiching a silicone rubber gasket between two plastic plates) and polymerized at 60°C for 8 hours. The prepared (P(AAm-co-AAc) hydrogel was removed from the mold, soaked in 0.075 M FeCl3 water bath for 1 day for ion binding, and then washed with pure solution to remove unwanted ions from the gel. Equilibrated in water for 1 day. The desired P(AAm-co-AAc)/Fe ³⁺ hydrogel was obtained.

2. Steps for producing glycerogel precursor

A glycerogel precursor was obtained by sequentially performing a solvent exchange process (0% → 25% → 50% → 100%) on the obtained P(AAm-co-AAc)/Fe ³⁺ hydrogel. P(AAm-co-AAc)/Fe ³⁺ GG precursor was obtained by sequentially immersing in glycerol aqueous solutions with 0%, 25%, 50%, and 100% glycerol contents for 12 hours, 12 hours, 24 hours, and 24 hours, respectively. .

3. Annealing step

The prepared GG precursor was wet annealed in a glycerol bath at 120°C for 2 hours and then slowly cooled to 25°C. The desired P(AAm-co-AAc)/Fe ³⁺ GG (thickness 1.6 mm), it was dry annealed at 120°C for 6 hours and slowly cooled to 25°C.

Example 4

Cellulose glycerogel (cellulose GG) was prepared as follows.

1. Steps to prepare hydrogel

Cellulose hydrogel was prepared using cellulose paper as follows. A small piece of cellulose filter paper was washed sequentially using water (~6 hours), ethanol (~6 hours), and DMAc (~12 hours) and then vacuum dried at 60°C. A 1.5% (w/w) cellulose solution was prepared by dissolving cellulose paper in DMAc/LiCl (92:8, w/w) solvent. The cellulose solution was cast into a 3 mm deep flat glass mold and exposed to ambient conditions (temperature: ∼25°C, humidity: 30–60%) for ∼3 days to induce gelation of cellulose through H-bond formation. The prepared organogel was sequentially equilibrated in ethanol (1d) and water (1d) to obtain a cellulose hydrogel.

2. Steps for producing glycerogel precursor

A glycerogel precursor was obtained through a sequential solvent exchange process (0% → 25% → 50% → 100%) for the obtained cellulose hydrogel. Cellulose GG precursors were obtained by sequentially immersing in glycerol aqueous solutions with 0%, 25%, 50%, and 100% glycerol content for 12 hours, 12 hours, 24 hours, and 24 hours, respectively.

3. Annealing step

The prepared GG precursor was dry-annealed in a sealed glass vial at 120 °C for 6 h and finally slowly cooled to 25 °C to determine the cellulose GG (thickness), which was used for further characterization. 2mm) was obtained.

Among the materials used in Examples 1 to 4 described above, acrylamide (AAm), acrylic acid (AAc), N,N'-methylenebisacrylamide (MBAA), dimethyl sulfoxide (DMSO), propylene glycol, iron chloride ( III) (FeCl3) was purchased from Daejeong Chemical Co., Ltd., and glycerol, ethylene glycol, N,N'-dimethylacetamide (DMAc), ethanol, and lithium chloride (LiCl) were purchased from Samcheon Pure Pharmaceutical (Korea). Cellulose-based filter paper (ADVANTEC) was purchased from Toyo Roshi Kaisha Ltd. (Japan). Poly(vinyl alcohol) (PVA, Mw: 89,000-98,000), ammonium persulfate (APS), and lithium perchlorate (LiClO4) were purchased from Sigma Aldrich. Tripropylene glycol (TriPG) was purchased from Acros Organics (Belgium). Carbon nanotube films (CNTs) (thickness: 10–20 μm) were purchased from Chengdu Organic Chemicals Co., Ltd., Chinese Academy of Sciences (China). All chemicals were used directly without further purification. Ultrapure deionized water was used in the experiments as needed.

Example 5

Patterned glycerogel was prepared as follows.

A pre-designed fractal-shaped silver pattern was created on the PVA GG surface obtained in Example 2 using a mask-induced ion sputtering method as follows. Soft PVA GG sheets (40 mm × 30 mm × 1.7 mm) made from a 4 wt% precursor solution were used. Sputtering was performed using a commercial ion sputtering machine (Magnetron sputtering system, ALPHAPLUS, Korea). The sample was covered with a pre-designed mask and fixed on a sample holder, which was then placed on the anode. Silver sputtering was performed in a vacuum (10 ^-6 Torr pressure) with an argon flow (flow rate 20 cm3 min ^-1 ) for 4 minutes by applying a direct current of 2A. Afterwards, the sample was extracted from the chamber, and the mask was removed to obtain the desired silver pattern of GG.

Example 6

The glycerogel-based electrolyte and supercapacitor were based on PVA-GG, and the electrolyte was manufactured using LiClO ₄ as a salt ion source as follows.

1. Steps to prepare hydrogel

Soft PVA gels were fabricated from a 5 wt% precursor solution of DMSO/water (75:25, w/w) using a 0.5 mm thick plastic mold.

2. Steps to prepare glycerogel precursor

After freezing (-50°C, 1 day) and thawing (25°C, 12 h), the gels were sequentially equilibrated in 25% (12 h) and 50% (12 h) glycerol (w/w). The gel was then equilibrated in a solution containing 20% LiClO ₄ in 75% aqueous glycerol (w/w) for 1 day. Finally, the gel was equilibrated in 20% LiClO ₄ solution in pure glycerol (w/w) for 1 day to obtain as-prepared PVA GG electrolyte (thickness: ∼0.2 mm).

3. Steps to manufacture a prototype supercapacitor

The gel electrolyte sheet was cut into squares measuring 20 mm × 20 mm and sandwiched between two parallel CNT films (20 mm × 20 mm) serving as anode and cathode.

4. Annealing step

A prototype supercapacitor consisting of sandwiched CNT electrodes and PVA GG-LiClO ₄ electrolyte was annealed in a closed glass vial at 90 °C for 3 h and slowly cooled to 25 °C to produce the desired PVA GG electrolyte-based flexible supercapacitor (CNT/PVA GG -LiClO ₄ ) was obtained.

Experiment method

1. Mechanical characterization

All mechanical tests were performed under ambient conditions (humidity: 30-60%, temperature: ~25°C) using a TEST ONE TO-100-1C universal testing machine (South Korea) equipped with a 10 kgf load cell.

(1) For tensile failure and force-loading tests, gel sheets (thickness: 1.6–2.6 mm) were cut into rectangular shapes (length: ~30 mm, width: ~3 mm). The sample was clamped along its length, keeping the distance between clamps at ~10 mm. The test was performed by moving the top clamp. Deformation was performed at 500%/min (0.083 s-1) for the tensile test and 100%/min (0.017 s-1) for the cyclic loading-unloading test. To evaluate the effect of temperature on mechanical properties, samples were initially incubated in chambers at each temperature for 7 days. Afterwards, samples were extracted from each chamber and immediately mounted on a tensile tester for testing. To evaluate the mechanical properties, three tests were performed for each gel type under each condition. Data are presented as mean values with absolute deviation.

(2) The fracture toughness of GG was evaluated using tensile fracture testing. Force-displacement curves were constructed from data obtained from tensile tests performed using notched and unnotched samples for each type of GG. Rectangular sample sheets were pre-cut to a width (w) of 20 mm and a length of 30 mm. In the notched sample, an initial notch of 8 mm (40% of the total width) was made along the width direction from the edge of the sample toward the center of the sample using a sharp blade. Notched and unnotched specimens were mounted on a tensile tester while maintaining an initial length of 10 mm (distance between clamps), and tensile tests were performed at a strain rate of 500%/min. The critical displacement point (Lc) at which cracks in the notched sample began to propagate was determined by analyzing pre-recorded images. The fracture energy (Γ) was calculated using the following equation:

(One)

where U(Lc) is the work done (area under the force-displacement curve) to deform the unnotched sample up to the Lc of the notched sample, and w and t are the width and thickness of the unnotched sample, respectively.

(3) Self-adhesion and lap shear testing

Self-adhesive cellulose and PVA GG were fabricated and the adhesive strength was evaluated through a lap shear test. To prepare self-adhesive cellulose GG, two rectangular sheets of cellulose GG (thickness: ∼2 mm) were first equilibrated in DMAc for ∼1 day. The intended bonded portions of the gel were soaked in a cellulose/LiCl/DMAc solution (originally used as a precursor for cellulose gel preparation) for 5 min and subsequently bonded by gentle pressing with a longitudinal overlap of ∼5 mm. It is then exposed to ambient conditions for ~1 day for interfacial hardening. Afterwards, the adhered gels were sequentially soaked in ethanol and water for ~12 h, respectively. Finally, self-adhesive cellulose GG was obtained by replacing the water in the adhesive gel with glycerol through a sequential solvent exchange process (0% → 25% → 50% → 100% glycerol). To fabricate self-adhesive PVA GG, the intended joint portion of two rectangular sheets of ~1.8 mm thick PVA GG (made from 5 wt% PVA precursor solution) was immersed in LiClO/glycerol solution (20:80, w/w) 140 Afterwards for 15 min at 80°C, the sheets were joined by gentle pressing to a longitudinal overlap of ∼5 mm and sequentially exposed to 80°C for 1 h and at ambient temperature for ∼12 h for interfacial curing. Finally, the bonded PVA GG was equilibrated in pure glycerol to remove free salt ions from the gel. To evaluate the bond strength of self-adhesive cellulose and PVA GG through a lap shear test, a tensile test was performed at 500% (distance between clamps)/min (500%/min) of the initial length, and the initial length was as follows. The adhesive strength of the ~10 mm gel was determined by dividing the maximum force required to break the interface by the shear area (overlap length × width: 5 mm × 5 mm).

2. Electrochemical measurements

All electrochemical measurements of the PVA GG electrolytes and supercapacitors fabricated in the examples were performed using a Metrohm Multi Autolab/M204 multichannel potentio-galvanostat (Netherlands).

A CNT/PVA GG-LiClO ₄ supercapacitor (length × width × thickness: 20 mm × 20 mm × 0.2 mm) was sandwiched between two parallel copper plates connected to a potentiostat-galvanostat via wires. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and GCD tests of the samples were performed in a two-electrode configuration. The sample-electrode setup was pre-equilibrated for 30 minutes at each measurement temperature, and then electrochemical measurements were performed by maintaining the setup at each temperature.

(1) EIS was performed in the frequency range of 106–0.1 Hz at an amplitude of 10 mV. The highest frequency value in the Nyquist plot was taken as the bulk resistance (R) of the sample. Ionic conductivity (■) was calculated using the following equation:

(2)

where l is the thickness of the gel electrolyte and A is the cross-sectional area of the electrode.

(2) CV was performed from 0 to 1 V at a scan rate of 1 to 50 mV s-1. From the CV curve, the area capacitance (mF cm-2) of supercapacitor C was calculated using the following equation:

(3)

Here, ∫I(V)dV is the area inside the CV loop, v is the scan speed, A is the surface area of one electrode, is the potential range.

(3) GCD was performed from 0 V to 1 V by applying various currents from 0.1 mA to 2 mA. The area capacitance (mF cm-2) of supercapacitor C was calculated from the GCD curve using the following equation:

(4)

Here, I is the applied current, Δt is the discharge time, A is the surface area of the electrode, and ΔV is the potential range.

Experimental Example 1

PAAm GG, PVA GG, P(AAm-co-AAc)/Fe ³⁺ GG, and cellulose GG prepared in Examples 1 to 4 were tested for extreme resistance as described above, and the results are shown in Figures 4 to 4. It is shown in Figure 12.

Four basic GGs, namely PAAm GG, PVA GG, P(AAm-co-AAc)/Fe ³⁺ GG, and cellulose GG, were fabricated using different polymers and cross-linking strategies, as shown in Figure 4 . PAAm GG (using covalent cross-linker); PVA GG (by H bond); poly(acrylamide-co-acrylic acid)/iron(III) (P(AAm-co-AAc)/Fe ³⁺ ) GG (with double crosslinker covalent and Fe ³⁺ -coordination)); and cellulose GG (by H-linked pure biopolymer structure).

As shown in Figures 5 a and b and Figure 6, GG of the present invention exhibited excellent long-term stability (~7 days) at -50 - 80 °C. When exposed to air for 1 week at -50, 25, and 80 °C, the weight change of all gels was maintained within ±10 wt.%. Small increases or decreases in weight were caused by absorption of atmospheric moisture or loss of glycerol from the gel network, respectively.

The properties and structures of various polymers and crosslinkers shown in Figure 4 facilitated the systematic fabrication of various GGs with a wide range of tunable mechanical performances, as shown in Figure 5 c to f.

For example, loosely cross-linked soft PAAm GG stretches >1200% and exhibits low modulus (0.09 ± 0.003 MPa) and strength (0.22 ± 0.02 MPa). PVA's strong H-bonds, semi-crystalline nature and excellent energy dissipation ability result in PVA having high stiffness (8.9 ± 0.2 MPa) and strength (8.5 ± 0.01 MPa) and extremely high strain energy (49.9 ± 0.4 MJ m ^-3 ). GG was created. Double cross-linked P(AAm-co-AAc)/Fe ³⁺ GG has excellent stiffness (1.6 ± 0.1 MPa), strength (7.1 ± 0.3 MPa) and tensile strength (23.5 ± 4.6 MJ) due to its excellent energy dissipation ability due to strong ionic coordination structure. m ^-3 ) showed a good balance. Physically crosslinked cellulose GG exhibited high stiffness (9.4 ± 0.9 MPa) and strength (2.9 ± 0.1 MPa) and low elasticity (∼100%) due to the highly solvated stretching structure of the rigid linear polymer with long persistence length. . The mechanical properties of each GG developed here can be further tuned by changing the monomer, polymer, and crosslinker composition.

Most importantly, as shown in Figures 5c to f and Figures 6 to 10, the mechanical properties of all GGs were 7°C at cryogenic (-50°C), room (25°C) and extremely high (80°C) temperatures. There was little change even after being exposed to air for several days. The extreme resistance of these glycerogels extends and relaxes at -50 and 80 °C, as shown in Figure 5 g and h, and the hydrogel and GG at 150 °C for 10 min, as shown in Figures 11 and 12. This was proven by applying thermal shock. GG survived without significant changes in weight and elasticity, but the hydrogel dried completely. A roadmap for designing an extremely tolerant GG is shown in Figure 4. It should be applicable to various functional polymers and cross-linking agents suitable for hydrogel production.

Experimental Example 2

Fracture toughness of PAAm GG, PVA GG, P(AAm-co-AAc)/Fe ³⁺ GG and cellulose GG prepared in Examples 1 to 4. Sangsuldon fracture using notched and unnotched samples. It was evaluated by testing, and the results are shown in Figures 13 and 14.

The fracture energy varies greatly depending on the polymer and crosslinker type. All developed GGs showed excellent fracture toughness. PAAm and PVA GG showed minimum (1581 J m ^-2 ) and maximum (19,627 J m ^-2 ) fracture energies, respectively (see c in Figure 13). As shown in Figure 14, the GG of the present invention had much higher fracture toughness than the corresponding hydrogel. The increase in the intermolecular and intramolecular H-bonding network caused by the three hydroxyl arms of glycerol over that by the single hydroxyl arm of water is inferred to be a major contributor to the higher fracture resistance of GG than its hydrogel counterpart. Afterwards, dynamic noncovalent bonds (H-bonding, ion-coordination) with an appropriate balance of weak and strong cross-linking points of P(AAm-co-AAc)/Fe ³⁺ and PVA GG were used to form natural rubbers reported so far. , giving it extreme toughness that surpasses most biological tissues and tough soft materials.

Experimental Example 3

PAAm GG, PVA GG, P(AAm-co-AAc)/Fe ³⁺ GG, and cellulose GG prepared in Examples 1 to 4 were evaluated for hysteresis, elasticity, plasticity, and self-healing, and the results were evaluated. It is shown in Figure 13 and Figures 15 to 19.

The elasticity, plasticity, energy dissipation and self-healing properties of the GG of the present invention can be modified using various cross-linking agents and polymers. As shown in Figure 13 d, the covalently cross-linked soft PAAm GG exhibited high nonlinear elasticity with marginal hysteresis despite ∼500% loading–unloading, similar to the PAAm hydrogel behavior. The hysteresis and strength of PAAm GG recovered within 5 min of load-removal test. These results suggest that the PAAm chains in the GG system have similar dynamics and structure to those in the hydrogel system.

As shown in Figure 13 e, unlike PAAm GG, PVA GG showed significant hysteresis with large plastic strain (∼250%) at 500% loading–unloading. Hysteresis demonstrated excellent energy dissipation ability derived from sacrificial bonds (H-bonds) with ~94% of the total work performed during 500% stretch. Most of the hysteresis and deformation remained unrecovered 12 h after the load-load test, indicating plastic deformation of PVA GG, which is atypical of normal hydrogels. As shown in Figure 15, softer PVA GG (tensile strength <1 MPa) prepared with extremely low polymer concentrations (5 and 3 wt.%) showed similar plastic behavior. As shown in Figure 16, PVA GG exhibits limiting hysteresis in the low strain region and exhibits excellent self-healing properties. After 50 loading-unloading cycles at 10% tension, the hysteresis and strength (~0.65 MPa) of the gel were fully recovered within 20 min.

As shown in Figure 13 f, the double cross-linked P(AAm-co-AAc)/Fe ³⁺ GG exhibits significant hysteresis at 150% strain, indicating energy dissipation through sacrificial bonding (ion coordination). Unlike PVA GG, most of the hysteresis and intensity of P(AAm-co-AAc)/Fe ³⁺ GG recovered within 30 min, suggesting almost reversibility of sacrificial bonding. As shown in Figure 17 a, the gel showed good recovery with limiting hysteresis up to 50% strain and the recovery time for strength and hysteresis decreased to 5 min. The excellent self-healing properties of the gel, as shown in Figure 17b, were further demonstrated by loading the sample at ∼50% tension and then unloading for 50 cycles. Most of the strength and hysteresis of the gel were recovered within 20 minutes.

As shown in Figure 13g, cellulose GG showed lower elasticity (<150%) than other GGs due to the large glycerol content and the rigid nature of cellulose polymer. However, cellulose GG exhibits significant hysteresis at 20% strain, suggesting efficient energy dissipation by H-bonds in the cellulose network. Most hysteresis and intensity were recovered within 30 min, indicating the reversibility of sacrificial bonding. These results strongly suggest that various GGs with tunable elasticity, plasticity, hysteresis, self-healing, and fatigue resistance can be designed by controlling the polymer and cross-linked structures.

As shown in Figure 13 h, the excellent plasticity of PVA GG was studied in depth by applying increasing cyclic strain rates. During the cycle, the gel exhibited plastic behavior with accumulated strain. As shown in Figure 18, the softer PVA GG exhibited similar behavior. The ratio between accumulated strain and applied strain increased significantly with the magnitude of applied strain (see Figure 195). High molecular density PVA GG exhibits high cumulative strain rates. These results suggest that PVA GG can be modulated with tunable plastic behavior. These properties are difficult to achieve with typical viscoelastic soft materials. Therefore, flexible devices with complex 3D configurations or patterned structures can be fabricated by plastically deformed bending/twisting/rolling/patterning.

Experimental Example 4

The self-adhesive ability of the cellulose GG prepared in Example 4 was evaluated, and the results are shown in Figures 20a, 20b, and 21.

As shown, the diverse application possibilities of GG are further expanded due to its excellent self-adhesive capabilities. A self-adhesion method was developed to efficiently bond cellulose-based hydrogels through ion-induced polymer reorganization applied to the GG system. Adhesion efficiency was quantitatively determined by performing lap shear tests on coaxially bonded GG (see Figures 20A and 20B). Bonded cellulose GG exhibited an adhesive strength of 0.77 MPa, which is much higher than that of adhesive hydrogels and similar to cartilage-bone or hydrogel-bone bonding. Additionally, the bonded sample was stretched by more than 100%, showing excellent adhesive toughness. As shown in Figure 21, soft PVA GG (made from 5 wt% PVA precursor) bonded similarly to cellulose GG showed excellent adhesive strength (0.21 MPa).

Experimental Example 5

Various customized functionalizations of the patterned glycerogel prepared in Example 5 demonstrated the potential for various next-generation electrical/electronic applications. That is, electrically conductive GG was prepared by coating silver on GG through high-speed ion sputtering. Using a pre-designed mask (see Figure 22), a thin layer of simple fractal-designed silver patterned loops was perfectly created on soft PVA GG (see Figure 23a-c). Facile LED illumination using patterned GG suggests that the silver patterns are sufficiently well connected at the microscopic level to complete the circuit (see d in Figure 23a). The stability and elasticity of the patterned GG were demonstrated at -50, 25, and 80 °C (see e-g in Figure 23b), with the gel stretching and recovering almost intact, showing very elastic polymer-metal interactions at the gel surface. It shows the formation of a stable pattern.

Experimental Example 6

The physical and electrochemical properties of the PVA GG electrolyte-based flexible supercapacitor (CNT/PVA GG-LiClO ₄ ) prepared in Example 6 were tested, and the results are shown in FIGS. 24a to 28.

As shown in Figure 24a, the PVA GG electrolyte-based flexible supercapacitor (CNT/PVA GG-LiClO ₄ ) prepared in Example 6 showed high flexibility under bending and torsion without interfacial defects. That is, because of its hydrophilicity and polarity, glycerol easily dissolves numerous common inorganic salts, so it is widely used in preparing battery and supercapacitor electrolytes as described above. LiClO ₄ , which is soluble in high concentrations of glycerol, is used to form ion-conducting GG (LiClO ₄ ions). Loaded PVA GG electrolyte) was prepared by simple diffusion-induced ion loading, sandwiching the prepared PVA GG electrolyte sheet (~0.2 mm thick) between two carbon nanotube (CNT)-based flexible electrode films to produce a prototype supercapacitor. It can be seen that the subsequent annealing step after fabrication induced strong electrode-gel-surface self-adhesion, giving excellent mechanical stability to the device.

Additionally, as shown in Figure 24b, the PVA GG electrolyte showed an ionic conductivity of 0.021±0.006 Sm ^-1 at 25°C. The conductivity decreased and increased with decreasing and increasing temperature, respectively, which was attributed to the change in solvent viscosity with temperature. GG achieved an extremely high conductivity of 0.11±0.03 S m ^-1 at 80°C and maintained an excellent conductivity of 0.003±0.0003 S m ^-1 at -20°C, which is similar to gel electrolytes used in energy storage devices.

The supercapacitor exhibits a quasi-rectangular closed loop in the cyclic voltammogram (CV), suggesting perfect electric double layer capacitor (EDLC) operation. Even at higher scan rates, the device exhibited a similar CV pattern within the 0-1 V voltage window (see Figure 25). The constant current charge/discharge (GCD) curve also showed a symmetrical triangle shape at various current rates, confirming perfect EDLC operation (see Figure 26). The area capacitance was calculated to be 5.29 ± 0.24 mF cm ^-2 at 1 mV s ^-1 (CV curve) and 7.46 ± 0.63 mF cm ^-2 at 0.1 mA (GCD curve). The areal capacitance obtained from the CV and GCD curves changed little with changes in scan rate and current density. Additionally, the device showed excellent performance at -20 to 80°C (see Figures 27a and 27b). The CV curve followed a closed quasi-rectangular loop. The areal capacitance of the device was 5.97 ± 0.49 and 2.21 ± 0.36 mF cm ^-2 at 80 and -20 °C, respectively. The change in area capacitance with temperature is very similar to the change in ionic conductivity of the GG electrolyte at each temperature.

As shown in Figure 28, the performance of the GG-based electrolyte and flexible supercapacitor of the present invention was compared with several recently reported high-performance supercapacitors, and the supercapacitor prepared in Example 6 showed excellent performance at -20 to 80°C. It shows capacitance (2.2-6mF cm ^-2 ), showing that it operates similarly to several recently reported high-performance supercapacitors. These results show that the excellent ionic solvation and extreme resistance of glycerol lead to excellent ionic conduction pathways in the GG-based electrolyte of the present invention.

Although the present invention has been illustrated and described with preferred embodiments as discussed above, it is not limited to the above-described embodiments and is not limited to the spirit of the present invention. Various changes and modifications will be possible.

Claims (24)

It is a glycerogel in which the water molecules of the hydrogel are replaced with glycerol, and is an extremely resistant glycerogel that exhibits the characteristic of maintaining a weight change within ±10 wt% for 7 days under temperature conditions ranging from -50℃ to 80℃.
According to claim 1,
Depending on the type of hydrogel, one or more mechanical properties selected from the group consisting of stretchability, stiffness, strength, modulus, and work of extension of the glycerogel Extremely resistant glycerogel characterized by change.
According to claim 2,
If the hydrogel is a polyacrylamide (PAAm) hydrogel, the glycerogel is PAAm glycerogel (GG), and the PAAm GG has an elasticity of more than 1200%, a modulus of 0.09 ± 0.003 MPa, and a strength of 0.22 ± 0.02 MPa. A glycerogel characterized by having extreme resistance.
According to claim 2,
If the hydrogel is a polyvinyl alcohol (PVA) hydrogel, the glycerogel is a PVA glycerogel, and the PVA GG has a rigidity of 8.9 ± 0.2 MPa, a strength of 8.5 ± 0.01 MPa, and a strength of 49.9 ± 0.4 MJ m ^-3 . An extremely resistant glycerogel characterized by having a strain energy (work of extension).
According to claim 2,
If the hydrogel is a poly(acrylamide-co-acrylic acid)/iron(III)(P(AAm-co-AAc)/Fe ³⁺ ) hydrogel, the glycerogel is P(AAm-co-AAc)/Fe ³⁺ glycerogel, and the P(AAm-co-AAc)/Fe ³⁺ GG has a stiffness of 1.6±0.1 MPa, a strength of 7.1±0.3 MPa, and a strain energy (work of extension) of 23.5±4.6 MJ m ^-3 ) Extremely resistant glycerogel characterized by having.
According to claim 2,
If the hydrogel is a cellulose hydrogel, the glycerogel is a cellulose glycerogel, and the cellulose GG has a rigidity of 9.4 ± 0.9 MPa, a strength of 2.9 ± 0.1 MPa, and an elasticity of less than 100%. Glycerose gel.
According to claim 1,
The glycerogel is an extremely resistant glycerogel, characterized in that the fracture toughness in the solid state is in the range of 1581 J m ^-2 to 19,627 J m ^-2 .
According to claim 1,
The glycerogel is an extremely resistant glycerogel, characterized in that the ionic conductivity in the liquid state is proportional to temperature.
According to claim 8,
The ionic conductivity of the glycerogel is 0.003±0.0003 S m ^-1 at -20°C, 0.021±0.006 S ^{m -1} at 25°C, and 0.11±0.03 S m ^-1 at 80°C. .
According to claim 1,
The glycerogel is an extremely resistant glycerogel, characterized in that it has self-welding ability and a bonding strength of 0.77 MPa or more.
Preparing a hydrogel;
Preparing a glycerogel precursor through solvent exchange in which water molecules in the hydrogel are replaced with glycerol; and
A method of producing extremely resistant glycerogel comprising an annealing step of heat-treating the glycerogel precursor and then cooling it to room temperature.
According to claim 11,
The solvent exchange is a rapid substitution reaction performed by immersing the hydrogel in a single concentration glycerol solution for several hours at 50°C to 100°C depending on the characteristics of the hydrogel, and a number of reactions in which the concentration of glycerol gradually increases from 0% to 100% at room temperature. A method of producing extremely resistant glycerogel, characterized in that it is carried out by any one of the slow substitution reactions carried out by sequentially immersing in a glycerol solution for several tens of hours.
According to claim 12,
If the hydrogel is a water-swelling hydrogel, a rapid substitution reaction is performed. A method of producing an extremely resistant glycerogel, characterized in that the water-swelling hydrogel is a polyacrylamide hydrogel.
According to claim 12,
In the step of preparing the glycerogel precursor, when the solvent exchange is performed through the rapid substitution reaction to produce the glycerogel precursor, the glycerogel precursor is added to a glycerol solution for several tens of hours at room temperature to ensure complete exchange of glycerol and water. A method for producing extremely resistant glycerogel, further comprising a stabilization step of immersion for a period of time.
According to claim 11,
In the annealing step, the heat treatment is performed in a dry or wet manner at 100°C to 200°C for several hours.
The method of claim 11, wherein if the prepared hydrogel is polyacrylamide (PAAm) hydrogel,
The step of preparing the glycerogel precursor includes preparing the PAAm glycerogel precursor by immersing the PAAm hydrogel in a 100% glycerol solution at 50°C to 70°C for 90 to 180 minutes; And a stabilization step of immersing the PAAm glycerogel precursor in a 100% glycerol solution at room temperature for 24 to 48 hours,
The annealing step is performed by placing the PAAm glycerogel precursor in a sealed reactor and dry-treating it at 100°C ± 1 for 2 to 4 hours, followed by slowly cooling to 24 to 26°C. How to make roselle.
The method of claim 11, wherein if the produced hydrogel is a polyvinyl alcohol (PVA) hydrogel,
The step of preparing the glycerogel precursor is to immerse the PVA hydrogel in a glycerol solution with glycerol concentrations of 25% ± 1 and 50% ± 1 at room temperature for 11 to 13 hours, and glycerol concentrations of 75% ± 1 and 100% ± 1, respectively. It is carried out including the step of sequentially immersing in a glycerol solution of % ± 1 for 23 to 25 hours,
The annealing step is performed by placing the PVA glycerogel precursor in a sealed reactor and heat-treating it dry at 110°C to 130°C for 5 to 7 hours, followed by gradual cooling to 24 to 26°C. Glycerogel manufacturing method.
The method of claim 11, wherein if the prepared hydrogel is a poly(acrylamide-co-acrylic acid)/iron(III) (P(AAm-co-AAc)/Fe ³⁺ ) hydrogel,
The step of preparing the glycerogel precursor is to place the P(AAm-co-AAc)/Fe ³⁺ hydrogel in a glycerol solution with a glycerol concentration of 0%±1 and 25%±1, respectively, at room temperature for 11 to 13 hours. During the process, it is carried out including the step of sequentially immersing in glycerol solutions with glycerol concentrations of 50% ± 1 and 100% ± 1 for 23 to 25 hours,
In the annealing step, the P(AAm-co-AAc)/Fe ³⁺ glycerogel precursor is placed in a glycerol bath, heat treated wet at 110°C to 130°C for 90 to 150 minutes, and then slowly heated to 24 to 26°C. A method of producing extremely resistant glycerogel, characterized in that it is carried out by cooling.
The method of claim 11, wherein if the produced hydrogel is a cellulose hydrogel,
The step of preparing the glycerogel precursor is to place the P(AAm-co-AAc)/Fe ³⁺ hydrogel in a glycerol solution with a glycerol concentration of 0%±1 and 25%±1, respectively, at room temperature for 11 to 13 hours. During the process, it is carried out including the step of sequentially immersing in glycerol solutions with glycerol concentrations of 50% ± 1 and 100% ± 1 for 23 to 25 hours,
The annealing step is performed by placing the cellulose glycerogel precursor in a sealed reactor and heat-treating it dry at 110°C to 130°C for 300 to 400 minutes, followed by gradual cooling to 24 to 26°C. Glycerogel manufacturing method.
The ultra-resistant glycerogel of any one of claims 1 to 10 or the ultra-resistant glycerogel prepared by the production method of any one of claims 11 to 19; and
An electrically conductive glycerogel comprising a metal pattern formed on the surface of the glycerogel.
According to claim 20,
An electrically conductive glycerogel that stretches and recovers without damage at -50 to 80°C.
An application product comprising the ultra-resistant glycerogel of any one of claims 1 to 10 or the ultra-resistant glycerogel prepared by the production method of any one of claims 11 to 19.
According to claim 22,
The application product is a flexible energy storage device, sensor, actuator, or robot.
According to claim 23,
If the energy storage device is a super capacitor, an application product characterized in that the capacitance is 2.2-6mF cm ^-2 at -20 to 80℃.