Ionic hydrogel and its preparation method and application

Abstract

This invention discloses an ionic hydrogel, its preparation method, and its applications. The ionic hydrogel of this invention comprises a hydrophilic polymer backbone, a polycation, an ionic liquid, and water. Its preparation method includes the following steps: mixing a hydrophilic monomer containing double bonds, a polycation, an ionic liquid, a crosslinking agent, an initiator, and water, followed by free radical polymerization via thermal initiation or ultraviolet light initiation. The ionic hydrogel of this invention not only significantly improves the flame-retardant properties of flammable materials and inhibits the spread of fire, but also possesses excellent ionic thermoelectric effects. It can be connected to a millivolt-level voltage alarm to form an early warning circuit, achieving sensitive and repeatable temperature sensing and fire early warning functions. This allows for the early detection of potential fire threats, preventing fires before they start. It can be applied in high-rise buildings, modern home appliances, and the Internet of Things (IoT) fields.

Description

Technical Field

[0001] This invention relates to the field of hydrogel technology, specifically to an ionic hydrogel, its preparation method, and its applications. Background Technology

[0002] Ionic hydrogels (IG) possess advantages such as high water content, tunable structure, good flexibility, good biocompatibility, and good conductivity, enabling functions such as resistance / capacitance sensing, temperature / pH response, and thermal / mechanical energy harvesting. They hold broad application prospects in human-computer interaction, energy, electronic devices, and soft robotics. However, the backbone of existing ionic hydrogels is primarily composed of flammable organic polymers. During prolonged use in high-temperature or dry environments, the water content in ionic hydrogels easily evaporates, significantly increasing the risk of fire and failing to meet increasingly stringent flame-retardant requirements. Furthermore, the functions of existing ionic hydrogels are relatively limited, failing to meet the urgent need for intelligent fire protection systems for flame-retardant materials.

[0003] Therefore, it is of great significance to develop an ionic hydrogel with excellent flame retardant properties and temperature sensing and fire early warning functions. Summary of the Invention

[0004] The purpose of this invention is to provide an ionic hydrogel, its preparation method, and its application.

[0005] The technical solution adopted in this invention is:

[0006] An ionic hydrogel comprising the following components by weight percentage:

[0007] Hydrophilic polymer backbone: 10%–40%;

[0008] Polycationic: 2%–10%;

[0009] Ionic liquids: 10%–50%;

[0010] Water: 8%–40%;

[0011] The hydrophilic polymer backbone is polymerized from hydrophilic monomers containing double bonds.

[0012] Preferably, the hydrophilic monomer containing a double bond is at least one of acrylamide, acrylic acid, sodium acrylate, 2-acrylamide-2-methylpropanesulfonic acid, and sodium 2-acrylamide-2-methylpropanesulfonate.

[0013] Preferably, the polycation is at least one of polydiallyldimethylammonium chloride, polyacryloyloxyethyltrimethylammonium chloride, and polymethacryloyloxyethyltrimethylammonium chloride.

[0014] Preferably, the ionic liquid is at least one of 1-butyl-3-methylimidazolium phosphate, 1-butylsulfonic acid-3-methylimidazolium phosphate, 1-propylsulfonic acid-3-methylimidazolium phosphate, 1-butyl-3-methylimidazolium hydrogen sulfate, 1-butylsulfonic acid-3-methylimidazolium hydrogen sulfate, and 1-propylsulfonic acid-3-methylimidazolium hydrogen sulfate.

[0015] A method for preparing an ionic hydrogel as described above includes the following steps: mixing a hydrophilic monomer containing a double bond, a polycation, an ionic liquid, a crosslinking agent, an initiator, and water, and then performing free radical polymerization via thermal initiation or ultraviolet light initiation to obtain the ionic hydrogel.

[0016] Preferably, the crosslinking agent is at least one of N,N-methylenebisacrylamide and ethylene glycol dimethacrylate.

[0017] Preferably, the amount of the crosslinking agent is 0.5% to 2% of the weight of the hydrophilic monomer containing double bonds.

[0018] Preferably, the initiator is at least one selected from potassium persulfate, ammonium persulfate, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, and 2-hydroxy-2-methylphenylacetone.

[0019] Preferably, the amount of the initiator is 0.5% to 2% of the weight of the hydrophilic monomer containing the double bond.

[0020] Preferably, the mixing is performed by mechanical stirring at a speed of 200 rpm to 1000 rpm for a duration of 5 min to 30 min.

[0021] Preferably, the thermal initiation temperature is 40℃~80℃, and the polymerization time is 30min~120min.

[0022] Preferably, the intensity of the ultraviolet light induced by the ultraviolet light is 50 mW·cm. -2 ~150mW·cm -2 The polymerization time is 1 min to 10 min.

[0023] A flame-retardant material comprising the aforementioned ionic hydrogel.

[0024] A fire warning device comprises a millivolt voltage alarm and the aforementioned ionized hydrogel, wherein the millivolt voltage alarm is connected to the ionized hydrogel via a wire.

[0025] The principle of this invention: The temperature sensing and fire early warning functions of the ionic hydrogel of this invention are mainly achieved by its excellent ionic thermoelectric effect. That is, the ionic carriers provided by the ionic liquid in the ionic hydrogel can migrate from the high-temperature end to the low-temperature end under the action of a temperature gradient and accumulate at the low-temperature end. Since the anions in the ionic liquid (e.g., dihydrogen phosphate and hydrogen sulfate) have hydrogen bond interactions with the amide, carboxyl, sulfonic acid and amino groups in the ionic hydrogel skeleton, and also have ionic interactions with the polycations, while the interaction between the cationic imidazole groups in the ionic liquid and the ionic hydrogel skeleton is relatively weak, under the action of a temperature gradient, the anions and cations in the ionic liquid exhibit ion-selective migration. The cations migrate relatively faster and accumulate more at the low-temperature end, thereby generating a potential difference between the high-temperature end and the low-temperature end. Moreover, there is a good linear relationship between the potential difference and the temperature difference. Therefore, sensitive temperature sensing and fire early warning functions can be achieved by monitoring the potential difference changes of the ionic hydrogel. In addition, the hydrophilic polymers and ionic liquids in ionic hydrogels have excellent synergistic flame retardant effects, generating flammable gases, diluting flammable gases, and expanding under the action of flammable gases to form a porous carbon layer, which plays a role in heat insulation and oxygen barrier, thus enabling ionic hydrogels to exert a highly efficient flame retardant effect.

[0026] The beneficial effects of this invention are: the ionic hydrogel of this invention can not only significantly improve the flame retardant properties of flammable materials and suppress the spread of fire, but also has excellent ionic thermoelectric effect. It can be connected with a millivolt-level voltage alarm to form an early warning circuit, realizing sensitive and repeatable temperature sensing and fire early warning functions. It can detect potential fire threats as early as possible and prevent fires from starting. It can be applied to high-rise buildings, modern home appliances and the Internet of Things.

[0027] Specifically:

[0028] 1) The ion hydrogel of the present invention has sensitive and repeatable temperature sensing and fire early warning functions, and the response signal is much higher than that of the existing thermoelectric fire early warning materials.

[0029] 2) The ionic hydrogel of the present invention has high flame retardant properties and provides good flame retardant protection for a variety of lightweight flammable substrates, enabling them to withstand prolonged flame burning.

[0030] 3) The ionic hydrogel of the present invention is simple to prepare and easy to apply. It can be coated onto the surface of flammable substrates by methods such as scraping, dipping, brushing and spin coating. Attached Figure Description

[0031] Figure 1 The image shows a screenshot from a video of the vertical burning of wood coated with the ionized hydrogel of Example 1.

[0032] Figure 2The ion thermoelectric potential test curve of the wood coated with ion hydrogel in Example 1 is shown.

[0033] Figure 3 The images show screenshots of vertical burning of wood coated with the ionized hydrogel of Example 1 and wood from the comparative example.

[0034] Figure 4 The temperature sensing performance test curve of the wood coated with ion hydrogel in Example 1 is shown.

[0035] Figure 5 The voltage response curve of the wood coated with ionized hydrogel in Example 1 is shown.

[0036] Figure 6 Screenshots from a fire warning test video of wood coated with ionized hydrogel in Example 1 and wood in a comparative example. Detailed Implementation

[0037] The present invention will be further explained and described below with reference to specific embodiments.

[0038] Example 1:

[0039] An ionic hydrogel, the preparation method of which includes the following steps:

[0040] A precursor solution was prepared by mixing 0.5 g of acrylamide, 2.5 g of a 20% (w / w) aqueous solution of polydiallyldimethylammonium chloride, 2 g of 1-butyl-3-methylimidazolium phosphate, 10 mg of N,N'-methylenebisacrylamide, and 10 mg of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone and stirring until homogeneous. The mixture was stirred at 500 rpm for 5 min, and then cured in a UV curing oven for 5 min at a UVA intensity of 100 mW·cm. -2 This yields an ionic hydrogel.

[0041] Example 2:

[0042] An ionic hydrogel, the preparation method of which includes the following steps:

[0043] A precursor solution was prepared by mixing 2g of acrylic acid, 0.5g of 20% (w / w) polydiallyldimethylammonium chloride aqueous solution, 2.5g of 1-butylsulfonic acid-3-methylimidazolium phosphate dihydrogen salt, 10mg of ethylene glycol dimethacrylate, and 10mg of potassium persulfate. The mixture was stirred until homogeneous at a stirring speed of 1000 rpm for 5 minutes. The solution was then placed in an oven at 80°C for 30 minutes to cure, thus obtaining the ionic hydrogel.

[0044] Example 3:

[0045] An ionic hydrogel, the preparation method of which includes the following steps:

[0046] A precursor solution was prepared by mixing 2g of 2-acrylamide-2-methylpropanesulfonic acid, 2.5g of a 20% (w / w) aqueous solution of polyacryloxyethyltrimethylammonium chloride, 0.5g of 1-propylsulfonic acid-3-methylimidazolium phosphate dihydrogen salt, 10mg of ethylene glycol dimethacrylate, and 10mg of 2-hydroxy-2-methylphenylacetone and stirring until homogeneous. The stirring speed was 200 rpm for 30 min, followed by curing in a UV curing oven for 10 min at a UVA intensity of 50 mW·cm. -2 This yields an ionic hydrogel.

[0047] Example 4:

[0048] An ionic hydrogel, the preparation method of which includes the following steps:

[0049] A precursor solution was prepared by mixing 0.5 g of acrylamide, 0.5 g of sodium 2-acrylamido-2-methylpropanesulfonate, 2 g of 20% (w / w) polymethacryloyloxyethyltrimethylammonium chloride aqueous solution, 1 g of 1-propylsulfonic acid-3-methylimidazolium phosphate dihydrogen salt, 1 g of 1-butyl-3-methylimidazolium phosphate dihydrogen salt, 10 mg of N,N'-methylenebisacrylamide, and 10 mg of ammonium persulfate and stirring until homogeneous. The stirring speed was 500 rpm and the stirring time was 5 min. The solution was then placed in an oven and cured at 40 °C for 120 min to obtain the ionic hydrogel.

[0050] Example 5:

[0051] An ionic hydrogel, the preparation method of which includes the following steps:

[0052] A precursor solution was prepared by mixing 0.5 g of acrylic acid, 0.5 g of sodium acrylate, 1 g of a 20% (w / w) aqueous solution of polyacryloyloxyethyltrimethylammonium chloride, 1 g of a 20% (w / w) aqueous solution of polymethacryloyloxyethyltrimethylammonium chloride, 2 g of 1-butyl-3-methylimidazolium phosphate dihydrogen salt, 10 mg of N,N'-methylenebisacrylamide, and 10 mg of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone and stirring until homogeneous. The stirring speed was 500 rpm for 5 min, followed by curing in a UV curing oven for 1 min at a UVA intensity of 150 mW·cm. -2 This yields an ionic hydrogel.

[0053] Example 6:

[0054] An ionic hydrogel, the preparation method of which includes the following steps:

[0055] A precursor solution was prepared by mixing 0.5 g of acrylamide, 2.5 g of a 20% (w / w) aqueous solution of polydiallyldimethylammonium chloride, 2 g of 1-butyl-3-methylimidazolium hydrogen sulfate, 10 mg of N,N'-methylenebisacrylamide, and 10 mg of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone and stirring until homogeneous. The stirring speed was 500 rpm for 5 min, followed by curing in a UV curing oven for 5 min at a UVA intensity of 100 mW·cm. -2 This yields an ionic hydrogel.

[0056] Example 7:

[0057] An ionic hydrogel, the preparation method of which includes the following steps:

[0058] A precursor solution was prepared by mixing 0.5 g of acrylamide, 2.5 g of a 20% (w / w) aqueous solution of polydiallyldimethylammonium chloride, 2 g of 1-butylsulfonic acid-3-methylimidazolium hydrogen sulfate, 10 mg of N,N'-methylenebisacrylamide, and 10 mg of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone and stirring until homogeneous. The mixture was stirred at 500 rpm for 5 min, and then cured in a UV curing oven for 5 min at a UVA intensity of 100 mW·cm. -2 This yields an ionic hydrogel.

[0059] Example 8:

[0060] An ionic hydrogel, the preparation method of which includes the following steps:

[0061] A precursor solution was prepared by mixing 0.5 g of acrylamide, 2.5 g of a 20% (w / w) aqueous solution of polydiallyldimethylammonium chloride, 2 g of 1-propylsulfonic acid-3-methylimidazolium hydrogen sulfate, 10 mg of N,N'-methylenebisacrylamide, and 10 mg of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone and stirring until homogeneous. The mixture was stirred at 500 rpm for 5 min, and then cured in a UV curing oven for 5 min at a UVA intensity of 100 mW·cm. -2 This yields an ionic hydrogel.

[0062] Comparative example:

[0063] Wood, polyurethane foam, and cotton fabric (none of which are coated with ionized hydrogel).

[0064] Performance testing:

[0065] Test method:

[0066] Ion thermoelectric potential test: An ion thermoelectric measurement platform was built using two Peltiers, thermocouples, glass slides, copper foil electrodes, and a digital multimeter. The distance between the two Peltiers was 30 mm. A DC power supply was used to power one of the Peltiers to generate a temperature difference. A thermocouple was attached to each Peltier, and their temperatures were recorded using an electronic thermometer. The test sample was then evenly placed on the two Peltiers, and electrodes were attached. The sample was connected to the digital multimeter with wires. The sample size was 40 mm × 10 mm × 1 mm.

[0067] Limiting oxygen index test: Using an oxygen index tester, when the test sample is burned to 50mm from the top in 3 minutes, the oxygen index at this point is recorded as its limiting oxygen index.

[0068] Vertical combustion test: Place the test sample 20mm above the Bunsen burner, exposing it to the Bunsen burner flame at a height of 40mm. Remove the flame after 20s and record the combustion phenomena and data.

[0069] Temperature sensing test: Place the two ends of a 10mm×50mm test sample on two different Peltiers, with each end of the sample having an area of ​​10mm×10mm on the Peltier. Then attach 0.2mm thick electrodes with a size of 5mm×50mm to each end, with the electrodes having a length of 5mm on the test sample. Adjust the voltage of the Peltiers and record its temperature with a thermometer. Use a digital multimeter (DMM6500 6 1 / 2, Keithley Instruments, USA) to record the voltage across the test sample at different temperature differences.

[0070] Fire warning test: Connect the test sample to the millivolt alarm through the wire, set the alarm voltage to 50mV, and then place the test sample 20mm above the alcohol lamp, exposing it to the alcohol lamp flame at a height of 40mm. Record the voltage curve and the warning response time.

[0071] Specific tests:

[0072] 1) The precursor solutions in Examples 1 to 8 were brushed onto the surfaces of wood, polyurethane foam and cotton fabric respectively, and then cured according to the curing methods in Examples 1 to 8 to obtain wood coated with ion hydrogel, polyurethane foam coated with ion hydrogel and cotton fabric coated with ion hydrogel.

[0073] 2) Ionized thermoelectric potential, limiting oxygen index, vertical burning, temperature sensing, and fire early warning tests were conducted on ionized hydrogel-coated wood, ionized hydrogel-coated polyurethane foam, and ionized hydrogel-coated cotton fabric, as well as the wood, polyurethane foam, and cotton fabric in the comparative examples. The test results are as follows:

[0074] a) Screenshot from a video of vertical burning of wood coated with ionized hydrogel in Example 1. Figure 1 As shown;

[0075] b) The ion thermoelectric potential test curve of the ionized hydrogel-coated wood in Example 1 is shown below. Figure 2 (In the figure, a is the voltage change curve under different temperature differences, and b is the fitting curve of the maximum voltage and temperature difference in a).

[0076] c) Screenshots of vertical burning of the ion-hydrogel-coated wood of Example 1 and the comparative example wood, as shown in the video. Figure 3 As shown;

[0077] d) The temperature sensing performance test curve of the wood coated with ion hydrogel in Example 1 is shown below. Figure 4 (In the figure, a is the voltage change curve at different temperatures, and b is the fitting curve of the maximum voltage and temperature difference in a).

[0078] e) The voltage response curve of the ion-hydrogel-coated wood in Example 1 is shown below. Figure 5 As shown;

[0079] f) Screenshots of fire warning tests on wood coated with ionized hydrogel in Example 1 and wood in the comparative example are shown below. Figure 6 As shown;

[0080] g) The thermoelectric potentials of each test sample are shown in Table 1:

[0081] Table 1 Thermoelectric potential

[0082]

[0083]

[0084] h) The limiting oxygen index of each test sample is shown in Table 2:

[0085] Table 2 Limiting Oxygen Index

[0086]

[0087] i) The vertical combustion self-extinguishing time of each test sample is shown in Table 3:

[0088] Table 3 Vertical Combustion Self-Extinguishing Time

[0089]

[0090]

[0091] j) The fire early warning response time of each test sample is shown in Table 4:

[0092] Table 4 Fire Early Warning Response Time

[0093]

[0094] As shown in Tables 1, 2, 3 and 4, the ionic hydrogels of Examples 1 to 8 can improve the flame retardant properties and ionic thermoelectric potential of wood, polyurethane foam and cotton fabric (flammable substrate) when coated on their surfaces, while also giving them sensitive temperature sensing and fire warning functions.

[0095] As shown in Table 1, the ionic hydrogels of Examples 1 to 8 have high ionic thermoelectric potentials and can be directly coated onto the surfaces of wood, polyurethane foam and cotton fabrics to impart ionic thermoelectric properties to them.

[0096] From Table 2, Table 3 and Figure 3 It can be seen that the ionic hydrogels of Examples 1-8 can exert a highly efficient flame-retardant effect on wood, polyurethane foam, and cotton fabrics. For example, after wood, polyurethane foam, and cotton fabrics are coated with the ionic hydrogel of Example 1, the limiting oxygen indices are 45.5%, 33.0%, and 37.0%, respectively, which are much higher than the 27.0%, 21.5%, and 20.0% of the wood, polyurethane foam, and cotton fabrics in the comparative examples. After wood, polyurethane foam, and cotton fabrics are coated with the ionic hydrogel of Example 1, they can all self-extinguish rapidly after leaving the flame in the vertical burning test, while the wood, polyurethane foam, and cotton fabrics in the comparative examples are completely burned. This shows that the ionic hydrogel of the present invention has a significant fire protection effect on flammable materials. This is because when exposed to flames or in a high-temperature environment, the water in the gel evaporates, producing flammable gases such as ammonia, which carry away heat and dilute flammable gases. In addition, the gel skeleton carbonizes and expands under the action of water vapor and ammonia to form a porous carbon layer. Furthermore, the P and S elements enhance the density and thermal stability of the carbon layer, playing a role in heat insulation and oxygen isolation, so that the gel can exert a highly efficient flame-retardant effect.

[0097] From Table 4 and Figures 4-6 It can be seen that the ionized hydrogels of Examples 1 to 8 can endow wood, polyurethane foam and cotton fabric with sensitive and repeatable temperature sensing and fire early warning functions.

[0098] Depend on Figure 2 It can be seen that the ion hydrogel of Example 1 can generate different voltages with changes in temperature difference, and there is a good linear relationship between voltage and temperature difference, with a correlation coefficient R. 2 The value is as high as 0.993, and it has good repeatability;

[0099] As shown in Table 4, wood, polyurethane foam and cotton fabric coated with the ionic hydrogel of Example 1 can trigger the fire warning device within 1.1s, 1.1s and 0.9s, respectively, while samples coated with the ionic hydrogel of other examples can also trigger the fire warning device within 2s.

[0100] Depend on Figure 6 It can be seen that when exposed to flame, the potential difference between the two ends of the wood coated with the ion hydrogel of Example 1 increases rapidly, exceeding 50mV in about 1 second, thereby triggering the warning device. This is because when exposed to flame, the ions inside the gel migrate due to the Soret effect and accumulate at the low temperature end. Due to the different migration rates of anions and cations, a potential difference is formed at both ends, thereby triggering the alarm device connected to it, thus achieving sensitive fire warning.

[0101] In summary, the ionic hydrogel of the present invention can improve the flame retardant properties of flammable materials such as wood, polyurethane foam and cotton fabrics, while giving them sensitive temperature sensing and fire early warning functions, and has broad application prospects in high-rise buildings, modern home appliances and the Internet of Things.

[0102] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A flame-retardant material, characterized in that, Contains an ionic hydrogel; the ionic hydrogel comprises the following components by mass percentage: Hydrophilic polymer backbone: 10%–40%; Polycationic: 2%–10%; Ionic liquids: 10%–50%; Water: 8%–40%; The hydrophilic polymer backbone is polymerized from hydrophilic monomers containing double bonds; The hydrophilic monomer containing a double bond is at least one of acrylamide, acrylic acid, sodium acrylate, 2-acrylamide-2-methylpropanesulfonic acid, and sodium 2-acrylamide-2-methylpropanesulfonate. The ionic liquid is at least one of 1-butyl-3-methylimidazolium phosphate, 1-butylsulfonic acid-3-methylimidazolium phosphate, 1-propylsulfonic acid-3-methylimidazolium phosphate, 1-butyl-3-methylimidazolium hydrogen sulfate, 1-butylsulfonic acid-3-methylimidazolium hydrogen sulfate, and 1-propylsulfonic acid-3-methylimidazolium hydrogen sulfate.

2. The flame-retardant material according to claim 1, characterized in that: The polycation is at least one of polydiallyldimethylammonium chloride, polyacryloyloxyethyltrimethylammonium chloride, and polymethacryloyloxyethyltrimethylammonium chloride.

3. The flame-retardant material according to claim 1, characterized in that: The ionic hydrogel is prepared by a method including the following steps: mixing a hydrophilic monomer containing a double bond, a polycation, an ionic liquid, a crosslinking agent, an initiator, and water, and then performing free radical polymerization by thermal initiation or ultraviolet light initiation to obtain the ionic hydrogel.

4. The flame-retardant material according to claim 3, characterized in that: The crosslinking agent is at least one of N,N-methylenebisacrylamide and ethylene glycol dimethacrylate; the initiator is at least one of potassium persulfate, ammonium persulfate, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone and 2-hydroxy-2-methylphenylacetone.

5. The flame-retardant material according to claim 3 or 4, characterized in that: The amount of the crosslinking agent is 0.5% to 2% of the weight of the hydrophilic monomer containing double bonds; the amount of the initiator is 0.5% to 2% of the weight of the hydrophilic monomer containing double bonds.

6. The flame-retardant material according to claim 3 or 4, characterized in that: The thermal initiation temperature is 40℃~80℃, and the polymerization time is 30min~120min; the ultraviolet light initiation intensity is 50mW·cm. -2 ~150mW·cm -2 The polymerization time is 1 min to 10 min.

7. A fire early warning device, characterized in that, The composition includes a millivolt voltage alarm and an ionic hydrogel; the millivolt voltage alarm is connected to the ionic hydrogel via a wire; the ionic hydrogel comprises the following components by mass percentage: Hydrophilic polymer backbone: 10%–40%; Polycationic: 2%–10%; Ionic liquids: 10%–50%; Water: 8%–40%; The hydrophilic polymer backbone is polymerized from hydrophilic monomers containing double bonds; The hydrophilic monomer containing a double bond is at least one of acrylamide, acrylic acid, sodium acrylate, 2-acrylamide-2-methylpropanesulfonic acid, and sodium 2-acrylamide-2-methylpropanesulfonate. The ionic liquid is at least one of 1-butyl-3-methylimidazolium phosphate, 1-butylsulfonic acid-3-methylimidazolium phosphate, 1-propylsulfonic acid-3-methylimidazolium phosphate, 1-butyl-3-methylimidazolium hydrogen sulfate, 1-butylsulfonic acid-3-methylimidazolium hydrogen sulfate, and 1-propylsulfonic acid-3-methylimidazolium hydrogen sulfate.

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