Preparation method and application of conductive fluorescent hydrogel with enhanced low-temperature mechanical property and adjustable gas detection limit

Abstract

The invention discloses a preparation method and application of conductive fluorescent hydrogel with enhanced low-temperature mechanical property and adjustable gas detection limit, and belongs to the field of conductive fluorescent hydrogel. The invention aims to solve the problems that the existing conductive fluorescent hydrogel cannot have excellent frost resistance, excellent mechanical property at room temperature, enhanced mechanical property at low temperature, visual fluorescence and adjustable gas detection limit at the same time. The method comprises the following steps: 1, preparing a distilled water / glycerol mixed solution; 2, adding lauryl sodium sulfate; 3, adding lauryl methacrylate into the lauryl sodium sulfate solution; 4, adding a fluorescent complex, acrylamide and 2-acrylamide-2-methyl-1-propanesulfonic acid into the reaction kettle; 5, adding potassium persulfate; and 6, heating and polymerizing. The device is applied to window opening / closing monitoring or NH3 detection in winter.

Description

Technical Field

[0001] The invention belongs to the field of conductive fluorescent hydrogels. Background Art

[0002] Conductive hydrogels, due to their flexibility, portability, and stretchability, have shown great potential for applications in health monitoring, environmental monitoring, and smart home monitoring. They cleverly combine the hydrogel's three-dimensional network structure, high water content, and excellent flexibility. Furthermore, the complex and ordered three-dimensional network structure formed by the hydrogel provides extremely favorable conditions for ion transport, enhancing the hydrogel's conductivity and making it an excellent candidate for flexible electronic sensors. However, conventional conductive hydrogels still have some limitations. They are prone to freezing below 0°C, resulting in a loss of flexibility, stretchability, and conductivity. This compromises the sensing performance and limits the functionality of conductive hydrogels, which rely on stretchability and flexibility for sensing. Combining stimuli-responsive fluorescent materials with conductive hydrogels can enable gas detection. Thanks to the hydrogel's excellent stretchability and fluorescence properties, gas sensors with varying detection limits can be developed, addressing the limitations of existing gas sensors, such as the lack of flexible detection limits and visualization.

[0003] Most conductive hydrogels with antifreeze properties are prepared by introducing inorganic salts (such as sodium chloride, zinc chloride, and lithium chloride), natural biomolecules (such as antifreeze proteins and silk proteins), and organic solvents (such as glycerol and dimethyl sulfoxide) into the hydrogel matrix. Compared to inorganic salts and antifreeze proteins, glycerol can not only achieve antifreeze and enhance mechanical properties through its abundant hydroxyl groups, but is also less susceptible to inactivation, resulting in a more durable antifreeze effect. However, this is far from sufficient to achieve even better mechanical properties at low temperatures. Furthermore, components that can enhance mechanical properties at low temperatures are particularly important, but existing conductive hydrogels with antifreeze properties cannot achieve enhanced mechanical properties at low temperatures.

[0004] Therefore, how to design and prepare a conductive fluorescent hydrogel with excellent antifreeze properties, excellent mechanical properties at room temperature, enhanced mechanical properties at low temperatures, visualized fluorescence, and adjustable gas detection limit is an urgent problem to be solved. Summary of the Invention

[0005] The present invention aims to solve the problem that existing conductive fluorescent hydrogels cannot simultaneously have excellent antifreeze performance, excellent mechanical properties at room temperature, enhanced mechanical properties at low temperatures, visualized fluorescence, and adjustable gas detection limits, and further provide a preparation method and application of conductive fluorescent hydrogels with enhanced low-temperature mechanical properties and adjustable gas detection limits.

[0006] A method for preparing a conductive fluorescent hydrogel with enhanced low-temperature mechanical properties and adjustable gas detection limit is carried out according to the following steps:

[0007] 1. Mix distilled water and glycerin evenly to obtain a distilled water / glycerin mixed solution;

[0008] 2. adding sodium lauryl sulfate to the distilled water / glycerol mixed solution and stirring to dissolve to form a transparent solution to obtain a sodium lauryl sulfate solution;

[0009] 3. Add lauryl methacrylate to the sodium lauryl sulfate solution, stir, and then sonicate until completely dissolved to obtain solution A;

[0010] 4. Add the fluorescent complex, acrylamide and 2-acrylamide-2-methyl-1-propanesulfonic acid to solution A and stir to obtain solution B;

[0011] 5. Add potassium persulfate to solution B and stir until completely dissolved to obtain a uniform and transparent solution C;

[0012] 6. Pour the uniform transparent solution C into a mold and heat to polymerize, thereby completing the preparation method of the conductive fluorescent hydrogel with enhanced low-temperature mechanical properties and adjustable gas detection limit.

[0013] Application of a conductive fluorescent hydrogel with enhanced low-temperature mechanical properties and adjustable gas detection limit, which is used for winter window opening / closing monitoring or NH3 detection.

[0014] Advantages of the present invention:

[0015] (1) The conductive fluorescent hydrogel prepared by the present invention has antifreeze properties and does not freeze at -20°C. It can also be stretched, bent, and twisted.

[0016] (2) The conductive fluorescent hydrogel prepared by the present invention has good mechanical properties at room temperature, with maximum stress and maximum strain of 160 kPa and 1110%, respectively;

[0017] (3) The conductive fluorescent hydrogel prepared by the present invention achieves enhanced low-temperature mechanical properties in the temperature range of 0°C to -20°C, with the maximum stress and maximum strain reaching 246 kPa and 2470% respectively at -20°C;

[0018] (4) The conductive fluorescent hydrogel prepared by the present invention has excellent electrical conductivity at 25°C to -20°C, with a high conductivity of 12.75S / m at 25°C and a conductivity of 6.3S / m at -20°C;

[0019] (5) The conductive fluorescent hydrogel prepared by the present invention utilizes its enhanced mechanical properties at low temperatures to monitor the open and closed status of windows at -20°C in winter;

[0020] (6) The conductive fluorescent hydrogel prepared by the present invention achieves a reduction in the gas detection limit under the action of external tensile force. The detection limit of the original hydrogel is 18.24 ppm, the detection limit of the hydrogel with 200% strain is 15.07 ppm, and the detection limit of the hydrogel with 400% strain is 10.89 ppm.

[0021] The present invention is used for a preparation method of a conductive fluorescent hydrogel with enhanced low-temperature mechanical properties and adjustable gas detection limit and application thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The size distribution diagram of solution A prepared in step 3 of Example 3 at different temperatures, a is 25°C, b is 4°C, and c is -20°C;

[0023] Figure 2 Actual images of the conductive fluorescent hydrogel prepared in step 6 of Example 3, showing the initial state, stretching, bending, and twisting: a) initial state at 25°C, b) initial state at -20°C, c) stretching at -20°C, d) bending at -20°C, and e) twisting at -20°C.

[0024] Figure 3 The following are histograms showing the mechanical properties of the conductive fluorescent hydrogel prepared in step 6 of Examples 1 to 7 at different temperatures: a) maximum stress-strain comparison at 25°C; b) maximum stress-strain comparison at -20°C.

[0025] Figure 4 A photo of the conductive fluorescent hydrogel prepared in step 6 of Example 3 being used to monitor the open and closed status of a window at -20°C in winter, as well as a resistance change diagram;

[0026] Figure 5 Optical photographs of the conductive fluorescent hydrogel prepared in step 6 of Example 3 at different response times when placed in a 20 ppm NH3 atmosphere at an original length of 20 mm;

[0027] Figure 6 Comparison of the fluorescence intensity of the conductive fluorescent hydrogel prepared in step 6 of Example 3 at different times under 20 ppm NH3 atmosphere at original length, fixed strain of 200%, and fixed strain of 400%;

[0028] Figure 7 a) Fluorescence emission spectrum and b) linear fit and detection limit of the relationship between NH3 concentration and fluorescence intensity of the conductive fluorescent hydrogel prepared in step 6 of Example 3 when the original length was placed in a 20 ppm to 500 ppm NH3 atmosphere for 1 min;

[0029] Figure 8a) Fluorescence emission spectrum and b) linear fit and detection limit of the NH3 concentration vs. fluorescence intensity of the conductive fluorescent hydrogel prepared in step 6 of Example 3, placed in a 200% strain atmosphere with 20 ppm to 500 ppm NH3 for 1 min;

[0030] Figure 9 a) Fluorescence emission spectrum and b) linear fit and detection limit of the NH3 concentration vs. fluorescence intensity of the conductive fluorescent hydrogel prepared in step 6 of Example 3, placed in a 20 ppm to 500 ppm NH3 atmosphere at a fixed strain of 400% for 1 min. DETAILED DESCRIPTION

[0031] Specific embodiment 1: This embodiment is a method for preparing a conductive fluorescent hydrogel with enhanced low-temperature mechanical properties and adjustable gas detection limit, which is carried out according to the following steps:

[0032] 1. Mix distilled water and glycerin evenly to obtain a distilled water / glycerin mixed solution;

[0033] 2. adding sodium lauryl sulfate to the distilled water / glycerol mixed solution and stirring to dissolve to form a transparent solution to obtain a sodium lauryl sulfate solution;

[0034] 3. Add lauryl methacrylate to the sodium lauryl sulfate solution, stir, and then sonicate until completely dissolved to obtain solution A;

[0035] 4. Add the fluorescent complex, acrylamide and 2-acrylamide-2-methyl-1-propanesulfonic acid to solution A and stir to obtain solution B;

[0036] 5. Add potassium persulfate to solution B and stir until completely dissolved to obtain a uniform and transparent solution C;

[0037] 6. Pour the uniform transparent solution C into a mold and heat to polymerize, thereby completing the preparation method of the conductive fluorescent hydrogel with enhanced low-temperature mechanical properties and adjustable gas detection limit.

[0038] This specific embodiment adds a substance that increases cross-linking density at low temperatures to achieve increased mechanical properties. Sodium dodecyl sulfate (SDS) can form stable micelles within the hydrogel at room temperature. After adding lauryl methacrylate (LMA) with a hydrophobic group, LMA can aggregate into the SDS micelles to act as a cross-linking agent (without the need to add additional chemical cross-linkers), forming a conductive fluorescent hydrogel with excellent mechanical properties. At low temperatures, more hydrogen bonds are formed between glycerol and water molecules and the SDS / LMA micelles, weakening the electrostatic repulsion, which is conducive to the formation of large-sized micelles and making the hydrogel network more dense. This results in a significant enhancement of the mechanical properties of the conductive fluorescent hydrogel at low temperatures.

[0039] 2-Acrylamido-2-methyl-1-propanesulfonic acid (AMPS) is a monomer with a sulfonic acid group, which dissociates into H + , forming negatively charged sulfonate ions that can form stable conductive paths, and acrylamide (AAm) as the matrix of the hydrogel. By adjusting the content of AMPS and AAm, a conductive fluorescent hydrogel with excellent mechanical properties can be obtained.

[0040] Advantages of this embodiment:

[0041] (1) The conductive fluorescent hydrogel prepared in this embodiment has antifreeze properties and does not freeze at -20°C. It can also be stretched, bent, and twisted.

[0042] (2) The conductive fluorescent hydrogel prepared in this embodiment has good mechanical properties at room temperature, with maximum stress and maximum strain of 160 kPa and 1110%, respectively;

[0043] (3) The conductive fluorescent hydrogel prepared in this embodiment achieves enhanced low-temperature mechanical properties in the temperature range of 0°C to -20°C, with the maximum stress and maximum strain reaching 246 kPa and 2470% at -20°C, respectively;

[0044] (4) The conductive fluorescent hydrogel prepared in this embodiment has excellent electrical conductivity at 25°C to -20°C, with a high conductivity of 12.75 S / m at 25°C and a conductivity of 6.3 S / m at -20°C.

[0045] (5) The conductive fluorescent hydrogel prepared in this embodiment utilizes its enhanced mechanical properties at low temperatures to monitor the open and closed status of windows at -20°C in winter;

[0046] (6) The conductive fluorescent hydrogel prepared in this embodiment achieves a reduction in the gas detection limit under the action of external tensile force. The detection limit of the original hydrogel is 18.24 ppm, the detection limit of the hydrogel with 200% strain is 15.07 ppm, and the detection limit of the hydrogel with 400% strain is 10.89 ppm.

[0047] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the volume ratio of distilled water to glycerol in step 1 is (1-10):1. Other aspects are the same as specific embodiment 1.

[0048] Specific embodiment 3: This embodiment differs from either specific embodiment 1 or 2 in that: in step 2, the volume ratio of the molar amount of sodium lauryl sulfate to the distilled water / glycerol mixed solution is 1 mmol:(8.5-20) mL; in step 2, sodium lauryl sulfate is added to the distilled water / glycerol mixed solution and stirred for 0.5-4 hours at a temperature of 0°C-50°C and a stirring speed of 200-1000 rpm to dissolve the sodium lauryl sulfate into a transparent solution, thereby obtaining a sodium lauryl sulfate solution. Other aspects are the same as specific embodiments 1 or 2.

[0049] Specific embodiment 4: This embodiment differs from any one of specific embodiments 1 to 3 in that: in step 3, lauryl methacrylate is added to the sodium dodecyl sulfate solution at a temperature of 20°C to 50°C and a stirring speed of 200 rpm to 1000 rpm, and stirred for 10 to 30 minutes; the ultrasonic treatment in step 3 is performed at a temperature of 20°C to 50°C and an ultrasonic power of 200 W to 300 W for 30 to 60 minutes until the solution is completely dissolved; and the molar ratio of lauryl methacrylate in step 3 to sodium dodecyl sulfate in step 2 is 1:(2 to 10). Other aspects are the same as specific embodiments 1 to 3.

[0050] Specific embodiment 5: The difference between this embodiment and specific embodiments 1 to 4 is that the fluorescent complex described in step 4 is specifically prepared according to the following steps:

[0051] ① Dissolving a lanthanide metal salt in distilled water at a heating temperature of 80° C. to 100° C. and a stirring speed of 200 rpm to 1000 rpm to obtain a lanthanide metal salt solution; the concentration of the lanthanide metal salt in the lanthanide metal salt solution is 0.01 mol / L to 0.05 mol / L;

[0052] ② Dissolving 2,6-pyridinedicarboxylic acid in distilled water at a heating temperature of 80° C. to 100° C. and a stirring speed of 200 rpm to 1000 rpm to obtain a 2,6-pyridinedicarboxylic acid solution; the concentration of 2,6-pyridinedicarboxylic acid in the 2,6-pyridinedicarboxylic acid solution is 0.05 mol / L to 0.15 mol / L;

[0053] ③ Add the lanthanide metal salt solution to the 2,6-pyridinedicarboxylic acid solution, then heat the mixture to 100°C to 120°C and stir for 1 to 2 hours at a temperature of 100°C to 120°C and a stirring speed of 200 rpm to 1000 rpm to obtain a white turbid solution. The solution is then filtered and repeatedly washed with distilled water to obtain a white solid, namely, the Ln(PDA)3 fluorescent complex. The molar ratio of the lanthanide metal salt in the lanthanide metal salt solution to the 2,6-pyridinedicarboxylic acid in the 2,6-pyridinedicarboxylic acid solution is 1:(0.4 to 37.5). Other modifications are the same as in Specific Embodiments 1 to 4.

[0054] Specific embodiment 6: This embodiment differs from specific embodiments 1 to 5 in that the lanthanide metal salt in step ① is europium chloride, europium nitrate, terbium chloride or terbium nitrate. Other aspects are the same as specific embodiments 1 to 5.

[0055] Specific embodiment 7: This embodiment differs from any one of specific embodiments 1 to 6 in that: the molar ratio of the fluorescent complex to acrylamide in step 4 is 1 mg:(0.5-15) mmol; the molar ratio of acrylamide to 2-acrylamido-2-methyl-1-propanesulfonic acid in step 4 is 1:(0-0.8); the molar ratio of the fluorescent complex in step 4 to lauryl methacrylate in step 3 is 1 mg:(0.0035-0.075) mmol; and in step 4, the fluorescent complex, acrylamide, and 2-acrylamido-2-methyl-1-propanesulfonic acid are added to solution A at a temperature of 0°C to 50°C and a stirring speed of 200 rpm to 1000 rpm and stirred for 10 min to 30 min. Other aspects are the same as specific embodiments 1 to 6.

[0056] Specific Embodiment 8: This embodiment differs from Specific Embodiments 1 to 7 in that the molar ratio of potassium persulfate in step 5 to acrylamide in step 4 is 1:(50-600); and in step 5, potassium persulfate is added to Solution B at a temperature of 0°C to 50°C and a stirring speed of 200 rpm to 1000 rpm and stirred for 10-30 minutes until completely dissolved. Other aspects are the same as Specific Embodiments 1 to 7.

[0057] Specific embodiment 9: This embodiment differs from specific embodiments 1 to 8 in that the polymerization reaction in step 6 is carried out at a heating temperature of 50° C. to 80° C. for 1 to 5 hours. Other aspects are the same as specific embodiments 1 to 8.

[0058] Specific embodiment 10: This embodiment provides an application of a conductive fluorescent hydrogel with enhanced low-temperature mechanical properties and adjustable gas detection limit, which is used for winter window opening / closing monitoring or NH3 detection.

[0059] The following examples are used to verify the beneficial effects of the present invention:

[0060] Example 1:

[0061] A method for preparing a conductive fluorescent hydrogel with enhanced low-temperature mechanical properties and adjustable gas detection limit is carried out according to the following steps:

[0062] 1. Mix distilled water and glycerin evenly to obtain a distilled water / glycerin mixed solution;

[0063] The volume ratio of distilled water to glycerol is 1:1;

[0064] 2. Add 0.35 mmol of sodium dodecyl sulfate (SDS) to 6 mL of a distilled water / glycerol mixture at 20°C and a stirring speed of 200 rpm and stir for 0.5 h to dissolve to form a transparent solution to obtain a sodium dodecyl sulfate solution;

[0065] 3. Add 0.075 mmol of lauryl methacrylate (LMA) to the sodium dodecyl sulfate solution at 20°C and a stirring speed of 500 rpm, stir for 10 minutes, and then ultrasonicate at 20°C and an ultrasonic power of 200 W for 30 minutes until completely dissolved to obtain solution A.

[0066] 4. Add 2 mg of the fluorescent complex, 12 mmol of acrylamide (AAm), and 2.4 mmol of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) to solution A at 20°C and a stirring speed of 200 rpm, and stir for 30 min to obtain solution B.

[0067] 5. Add 0.05 mmol of potassium persulfate to solution B at 20°C and a stirring speed of 200 rpm and stir for 20 minutes until completely dissolved to obtain a homogeneous and transparent solution C.

[0068] 6. Pour the uniform transparent solution C into the mold and heat it at 50°C for 5 hours to obtain a conductive fluorescent hydrogel.

[0069] The fluorescent complex described in step 4 is specifically prepared according to the following steps:

[0070] ① Dissolving a lanthanide metal salt in distilled water at a heating temperature of 90° C. and a stirring speed of 500 rpm to obtain a lanthanide metal salt solution; the concentration of the lanthanide metal salt in the lanthanide metal salt solution is 0.02 mol / L; the lanthanide metal salt is europium chloride (EuCl3);

[0071] ② Under the conditions of a heating temperature of 90° C. and a stirring speed of 500 rpm, dissolving 2,6-pyridinedicarboxylic acid in distilled water to obtain a 2,6-pyridinedicarboxylic acid solution; the concentration of 2,6-pyridinedicarboxylic acid in the 2,6-pyridinedicarboxylic acid solution is 0.05 mol / L;

[0072] ③ Add 20 mL of lanthanide metal salt solution to 20 mL of 2,6-pyridinedicarboxylic acid solution, then heat to 110°C and stir for 1 hour at 110°C and 500 rpm to obtain a white turbid solution. Finally, filter and wash repeatedly with distilled water to obtain a white solid, namely, Eu(PDA)3 fluorescent complex.

[0073] Example 2:

[0074] A method for preparing a conductive fluorescent hydrogel with enhanced low-temperature mechanical properties and adjustable gas detection limit is carried out according to the following steps:

[0075] 1. Mix distilled water and glycerin evenly to obtain a distilled water / glycerin mixed solution;

[0076] The volume ratio of distilled water to glycerol is 2:1;

[0077] 2. Add 0.35 mmol of sodium dodecyl sulfate (SDS) to 6 mL of a distilled water / glycerol mixture at 30°C and a stirring speed of 300 rpm and stir for 1 h to dissolve to form a transparent solution to obtain a sodium dodecyl sulfate solution;

[0078] 3. Add 0.075 mmol of lauryl methacrylate (LMA) to the sodium dodecyl sulfate solution at 30°C and 300 rpm, stirring for 20 minutes, and then ultrasonicate at 30°C and 200 W for 40 minutes until completely dissolved to obtain solution A.

[0079] 4. Add 5 mg of the fluorescent complex, 18 mmol of acrylamide (AAm), and 2.4 mmol of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) to solution A at 30°C and a stirring speed of 300 rpm, and stir for 30 min to obtain solution B.

[0080] 5. Add 0.1 mmol of potassium persulfate to solution B at 30°C and a stirring speed of 300 rpm and stir for 30 minutes until completely dissolved to obtain a homogeneous and transparent solution C.

[0081] 6. Pour the uniform transparent solution C into the mold and heat it at 60°C for 2 hours to obtain a conductive fluorescent hydrogel.

[0082] The fluorescent complex described in step 4 is specifically prepared according to the following steps:

[0083] ① Dissolving a lanthanide metal salt in distilled water at a heating temperature of 90° C. and a stirring speed of 300 rpm to obtain a lanthanide metal salt solution; the concentration of the lanthanide metal salt in the lanthanide metal salt solution is 0.02 mol / L; the lanthanide metal salt is europium nitrate (Eu(NO3)3);

[0084] ② Under the conditions of heating temperature of 90° C. and stirring speed of 300 rpm, dissolving 2,6-pyridinedicarboxylic acid in distilled water to obtain a 2,6-pyridinedicarboxylic acid solution; the concentration of 2,6-pyridinedicarboxylic acid in the 2,6-pyridinedicarboxylic acid solution is 0.06 mol / L;

[0085] ③ Add 20 mL of lanthanide metal salt solution to 40 mL of 2,6-pyridinedicarboxylic acid solution, then heat to 100°C and stir for 1 hour at 100°C and 300 rpm to obtain a white turbid solution. Finally, filter and wash repeatedly with distilled water to obtain a white solid, namely, Eu(PDA)3 fluorescent complex.

[0086] Example 3:

[0087] A method for preparing a conductive fluorescent hydrogel with enhanced low-temperature mechanical properties and adjustable gas detection limit is carried out according to the following steps:

[0088] 1. Mix distilled water and glycerin evenly to obtain a distilled water / glycerin mixed solution;

[0089] The volume ratio of distilled water to glycerol is 5:1;

[0090] 2. Add 0.7 mmol of sodium dodecyl sulfate (SDS) to 6 mL of a distilled water / glycerol mixture at 20°C and a stirring speed of 400 rpm and stir for 1.5 hours to dissolve into a transparent solution to obtain a sodium dodecyl sulfate solution.

[0091] 3. Add 0.15 mmol of lauryl methacrylate (LMA) to the sodium dodecyl sulfate solution at 20°C and a stirring speed of 400 rpm, and stir for 30 minutes. Then, ultrasonicate at 30°C and an ultrasonic power of 240 W for 60 minutes until the solution is completely dissolved, to obtain solution A.

[0092] 4. Add 2 mg of the fluorescent complex, 24 mmol of acrylamide (AAm), and 2.4 mmol of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) to solution A at 20°C and a stirring speed of 400 rpm, and stir for 20 min to obtain solution B.

[0093] 5. Add 0.12 mmol of potassium persulfate to solution B at 20°C and a stirring speed of 400 rpm and stir for 30 minutes until completely dissolved to obtain a homogeneous and transparent solution C.

[0094] 6. Pour the uniform transparent solution C into the mold and heat it at 60°C for 4 hours to obtain a conductive fluorescent hydrogel.

[0095] The fluorescent complex described in step 4 is specifically prepared according to the following steps:

[0096] ① Dissolving a lanthanide metal salt in distilled water at a heating temperature of 90° C. and a stirring speed of 400 rpm to obtain a lanthanide metal salt solution; the concentration of the lanthanide metal salt in the lanthanide metal salt solution is 0.03 mol / L; the lanthanide metal salt is terbium chloride (TbCl3);

[0097] ② Under the conditions of heating temperature of 90° C. and stirring speed of 400 rpm, dissolving 2,6-pyridinedicarboxylic acid in distilled water to obtain a 2,6-pyridinedicarboxylic acid solution; the concentration of 2,6-pyridinedicarboxylic acid in the 2,6-pyridinedicarboxylic acid solution is 0.09 mol / L;

[0098] ③ Add 50 mL of lanthanide metal salt solution to 50 mL of 2,6-pyridinedicarboxylic acid solution, then heat to 120°C and stir for 1.5 hours at 120°C and 400 rpm to obtain a white turbid solution. Finally, filter and wash repeatedly with distilled water to obtain a white solid, namely, Tb(PDA)3 fluorescent complex.

[0099] Example 4:

[0100] A method for preparing a conductive fluorescent hydrogel with enhanced low-temperature mechanical properties and adjustable gas detection limit is carried out according to the following steps:

[0101] 1. Mix distilled water and glycerin evenly to obtain a distilled water / glycerin mixed solution;

[0102] The volume ratio of distilled water to glycerol is 4:1;

[0103] 2. Add 0.7 mmol of sodium dodecyl sulfate (SDS) to 6 mL of a distilled water / glycerol mixture at 50°C and a stirring speed of 500 rpm and stir for 2 h to dissolve to form a transparent solution to obtain a sodium dodecyl sulfate solution;

[0104] 3. Add 0.09 mmol of lauryl methacrylate (LMA) to the sodium dodecyl sulfate solution at 50°C and 500 rpm, stirring for 10 min, and then ultrasonicate at 40°C and 300 W for 30 min until completely dissolved to obtain solution A.

[0105] 4. Add 15 mg of the fluorescent complex, 30 mmol of acrylamide (AAm), and 2.4 mmol of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) to solution A at 50°C and a stirring speed of 500 rpm, and stir for 30 min to obtain solution B.

[0106] 5. Add 0.2 mmol of potassium persulfate to solution B at 50°C and a stirring speed of 500 rpm and stir for 20 minutes until completely dissolved to obtain a homogeneous and transparent solution C.

[0107] 6. Pour the uniform transparent solution C into the mold and heat it at 70°C for 3 hours to obtain a conductive fluorescent hydrogel.

[0108] The fluorescent complex described in step 4 is specifically prepared according to the following steps:

[0109] ① Dissolving a lanthanide metal salt in distilled water at a heating temperature of 90° C. and a stirring speed of 500 rpm to obtain a lanthanide metal salt solution; the concentration of the lanthanide metal salt in the lanthanide metal salt solution is 0.015 mol / L; the lanthanide metal salt is terbium nitrate (Tb(NO3)3);

[0110] ② Under the conditions of a heating temperature of 90° C. and a stirring speed of 500 rpm, dissolving 2,6-pyridinedicarboxylic acid in distilled water to obtain a 2,6-pyridinedicarboxylic acid solution; the concentration of 2,6-pyridinedicarboxylic acid in the 2,6-pyridinedicarboxylic acid solution is 0.06 mol / L;

[0111] ③ Add 30 mL of lanthanide metal salt solution to 30 mL of 2,6-pyridinedicarboxylic acid solution, then heat to 100°C and stir for 2 h at 100°C and 500 rpm to obtain a white turbid solution. Finally, filter and wash repeatedly with distilled water to obtain a white solid, namely, Tb(PDA)3 fluorescent complex.

[0112] Embodiment 5:

[0113] A method for preparing a conductive fluorescent hydrogel with enhanced low-temperature mechanical properties and adjustable gas detection limit is carried out according to the following steps:

[0114] 1. Mix distilled water and glycerin evenly to obtain a distilled water / glycerin mixed solution;

[0115] The volume ratio of distilled water to glycerol is 5:1;

[0116] 2. Add 0.35 mmol of sodium dodecyl sulfate (SDS) to 6 mL of a distilled water / glycerol mixture at 50°C and a stirring speed of 600 rpm and stir for 1 hour to dissolve to form a transparent solution to obtain a sodium dodecyl sulfate solution;

[0117] 3. Add 0.15 mmol of lauryl methacrylate (LMA) to the sodium dodecyl sulfate solution at 50°C and a stirring speed of 600 rpm, stir for 10 minutes, and then ultrasonicate at 50°C and a power of 300 W for 30 minutes until completely dissolved to obtain solution A.

[0118] 4. Add 5 mg of the fluorescent complex, 24 mmol of acrylamide (AAm), and 0 mmol of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) to solution A at 50°C and a stirring speed of 600 rpm, and stir for 20 min to obtain solution B.

[0119] 5. Add 0.05 mmol of potassium persulfate to solution B at 50°C and a stirring speed of 600 rpm and stir for 10 minutes until completely dissolved to obtain a homogeneous and transparent solution C.

[0120] 6. Pour the uniform transparent solution C into the mold and heat it at 80°C for 2 hours to obtain a conductive fluorescent hydrogel.

[0121] The fluorescent complex described in step 4 is specifically prepared according to the following steps:

[0122] ① Dissolving a lanthanide metal salt in distilled water at a heating temperature of 90° C. and a stirring speed of 600 rpm to obtain a lanthanide metal salt solution; the concentration of the lanthanide metal salt in the lanthanide metal salt solution is 0.015 mol / L; the lanthanide metal salt is europium chloride (EuCl3);

[0123] ② Under the conditions of a heating temperature of 90° C. and a stirring speed of 600 rpm, dissolving 2,6-pyridinedicarboxylic acid in distilled water to obtain a 2,6-pyridinedicarboxylic acid solution; the concentration of 2,6-pyridinedicarboxylic acid in the 2,6-pyridinedicarboxylic acid solution is 0.05 mol / L;

[0124] ③ Add 30 mL of lanthanide metal salt solution to 30 mL of 2,6-pyridinedicarboxylic acid solution, then heat to 100°C and stir for 1 hour at 100°C and 600 rpm to obtain a white turbid solution. Finally, filter and wash repeatedly with distilled water to obtain a white solid, namely, Eu(PDA)3 fluorescent complex.

[0125] Example 6:

[0126] A method for preparing a conductive fluorescent hydrogel with enhanced low-temperature mechanical properties and adjustable gas detection limit is carried out according to the following steps:

[0127] 1. Mix distilled water and glycerin evenly to obtain a distilled water / glycerin mixed solution;

[0128] The volume ratio of distilled water to glycerol is 6:1;

[0129] 2. Add 0.7 mmol of sodium dodecyl sulfate (SDS) to 6 mL of a distilled water / glycerol mixture at 40°C and a stirring speed of 700 rpm and stir for 2 h to dissolve to form a transparent solution to obtain a sodium dodecyl sulfate solution;

[0130] 3. Add 0.075 mmol of lauryl methacrylate (LMA) to the sodium dodecyl sulfate solution at 40°C and a stirring speed of 700 rpm, and stir for 20 minutes. Then, ultrasonicate at 30°C and an ultrasonic power of 240 W for 30 minutes until the solution is completely dissolved, to obtain solution A.

[0131] 4. Add 2 mg of the fluorescent complex, 24 mmol of acrylamide (AAm), and 4.8 mmol of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) to solution A at 40°C and a stirring speed of 700 rpm, and stir for 30 min to obtain solution B.

[0132] 5. Add 0.15 mmol of potassium persulfate to solution B at 40°C and a stirring speed of 700 rpm and stir for 20 min until completely dissolved to obtain a homogeneous and transparent solution C.

[0133] 6. Pour the uniform transparent solution C into the mold and heat it at 60°C for 3 hours to obtain a conductive fluorescent hydrogel.

[0134] The fluorescent complex described in step 4 is specifically prepared according to the following steps:

[0135] ① Dissolving a lanthanide metal salt in distilled water at a heating temperature of 90° C. and a stirring speed of 700 rpm to obtain a lanthanide metal salt solution; the concentration of the lanthanide metal salt in the lanthanide metal salt solution is 0.025 mol / L; the lanthanide metal salt is europium nitrate (Eu(NO3)3);

[0136] ② Under the conditions of a heating temperature of 90° C. and a stirring speed of 700 rpm, dissolving 2,6-pyridinedicarboxylic acid in distilled water to obtain a 2,6-pyridinedicarboxylic acid solution; the concentration of 2,6-pyridinedicarboxylic acid in the 2,6-pyridinedicarboxylic acid solution is 0.09 mol / L;

[0137] ③ Add 30 mL of lanthanide metal salt solution to 30 mL of 2,6-pyridinedicarboxylic acid solution, then heat to 100°C and stir for 2 hours at 100°C and 700 rpm to obtain a white turbid solution. Finally, filter and wash repeatedly with distilled water to obtain a white solid, namely, Eu(PDA)3 fluorescent complex.

[0138] Embodiment seven:

[0139] A method for preparing a conductive fluorescent hydrogel with enhanced low-temperature mechanical properties and adjustable gas detection limit is carried out according to the following steps:

[0140] 1. Mix distilled water and glycerin evenly to obtain a distilled water / glycerin mixed solution;

[0141] The volume ratio of distilled water to glycerol is 7:1;

[0142] 2. Add 0.7 mmol of sodium dodecyl sulfate (SDS) to 6 mL of a distilled water / glycerol mixture at 30°C and 800 rpm, stirring for 2 h to dissolve the mixture to form a transparent solution, thereby obtaining a sodium dodecyl sulfate solution.

[0143] 3. Add 0.12 mmol of lauryl methacrylate (LMA) to the sodium dodecyl sulfate solution at 30°C and 800 rpm, stirring for 30 minutes, and then ultrasonicate at 50°C and 200 W for 30 minutes until completely dissolved, to obtain solution A.

[0144] 4. Add 20 mg of the fluorescent complex, 24 mmol of acrylamide (AAm), and 7.2 mmol of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) to solution A at 30°C and a stirring speed of 800 rpm, and stir for 30 min to obtain solution B.

[0145] 5. Add 0.2 mmol of potassium persulfate to solution B at 30°C and a stirring speed of 800 rpm and stir for 30 minutes until completely dissolved to obtain a homogeneous and transparent solution C.

[0146] 6. Pour the uniform transparent solution C into the mold and heat it at 60°C for 5 hours to obtain a conductive fluorescent hydrogel.

[0147] The fluorescent complex described in step 4 is specifically prepared according to the following steps:

[0148] ① Dissolving a lanthanide metal salt in distilled water at a heating temperature of 90° C. and a stirring speed of 800 rpm to obtain a lanthanide metal salt solution; the concentration of the lanthanide metal salt in the lanthanide metal salt solution is 0.035 mol / L; the lanthanide metal salt is terbium chloride (TbCl3);

[0149] ② Under the conditions of a heating temperature of 90° C. and a stirring speed of 800 rpm, dissolving 2,6-pyridinedicarboxylic acid in distilled water to obtain a 2,6-pyridinedicarboxylic acid solution; the concentration of 2,6-pyridinedicarboxylic acid in the 2,6-pyridinedicarboxylic acid solution is 0.105 mol / L;

[0150] ③ Add 20 mL of lanthanide metal salt solution to 30 mL of 2,6-pyridinedicarboxylic acid solution, then heat to 100°C and stir for 1 hour at 100°C and 800 rpm to obtain a white turbid solution. Finally, filter and wash repeatedly with distilled water to obtain a white solid, namely, Tb(PDA)3 fluorescent complex.

[0151] (1) Dynamic light scattering of SDS / LMA:

[0152] Figure 1 The following are size distribution diagrams of solution A prepared in step 3 of Example 3 at different temperatures, where a is 25°C, b is 4°C, and c is -20°C. The test results show that the average size at 25°C is 106 nm, the average size at 4°C is 199 nm, and the average size at -20°C is 255 nm. As the temperature decreases, the size of the SDS / LMA micelles gradually increases.

[0153] (2) Antifreeze properties of hydrogel:

[0154] Figure 2 Actual pictures of the initial state, stretching, bending, and twisting of the conductive fluorescent hydrogel prepared in step six of Example 3: a) initial state at 25°C, b) initial state at -20°C, c) stretching at -20°C, d) bending at -20°C, and e) twisting at -20°C. As can be seen from the figure, the conductive fluorescent hydrogel is stretchable and flexible at low temperatures, which is conducive to the application of conductive fluorescent hydrogels at low temperatures.

[0155] (3) Mechanical properties of hydrogels:

[0156] Figure 3 The following are histograms of the mechanical properties test of the conductive fluorescent hydrogel prepared in step 6 of Examples 1 to 7 at different temperatures, a) maximum stress-strain comparison diagram at 25°C, b) maximum stress-strain comparison diagram at -20°C; from the test results, it can be observed that the stress and strain of Example 1 at 25°C are 1650% and 35kPa, and the stress and strain at -20°C are 2777% and 103kPa; the stress and strain of Example 2 at 25°C are 1374% and 123kPa, and the stress and strain at -20°C are 2739% and 203kPa; the stress and strain of Example 3 at 25°C are 1110% and 160kPa, and the stress and strain at -20°C are The stress and strain of Example 4 at 25°C are 611% and 124 kPa, and the stress and strain at -20°C are 2095% and 296 kPa; the stress and strain of Example 5 at 25°C are 2114% and 37 kPa, and the stress and strain at -20°C are 2709% and 76 kPa; the stress and strain of Example 6 at 25°C are 1422% and 130 kPa, and the stress and strain at -20°C are 2550% and 222 kPa; the stress and strain of Example 7 at 25°C are 642% and 120 kPa, and the stress and strain at -20°C are 2381% and 216 kPa. It can be seen from the figure and data that the overall stress and strain at -20°C are greater than those at 25°C. This is due to the dense internal network of the hydrogel caused by the change in the size of SDS / LMA micelles, which enhances the mechanical properties of the low-temperature conductive fluorescent hydrogel.

[0157] (4) Conductivity test of hydrogel:

[0158] The conductive fluorescent hydrogel prepared in step 6 of Examples 1 to 7 exhibits excellent conductive properties at both 25°C and -20°C. The conductive fluorescent hydrogel prepared in step 6 of Example 3 has a high conductivity of 12.75 S / m at 25°C and still has a conductivity of 6.3 S / m at -20°C.

[0159] (5) Winter window opening / closing monitoring using hydrogel:

[0160] A flexible strain sensor was constructed by connecting a multimeter via a wire to monitor the opening / closing status of a window in winter at -20°C. The two ends of the conductive fluorescent hydrogel prepared in step 6 of Example 3 were adhered to the edges of the window. Copper wires were used to connect the two ends of the conductive fluorescent hydrogel to the positive and negative terminals of a multimeter to form a closed circuit. The multimeter was set to read the resistance change of the hydrogel in real time. Figure 4 This is a photo of the conductive fluorescent hydrogel prepared in step 6 of Example 3, applied to monitoring the open and closed status of a window at -20°C in winter, along with a resistance change graph. The test results show that when the window is opened to 60° and the hydrogel is stretched to approximately 2000% strain, the relative resistance of the conductive fluorescent hydrogel increases dramatically. After closing the window, the relative resistance change returns to its initial value. When the window is opened at a 30° angle for 10 seconds, the relative resistance change remains stable at approximately 5700%, outputting an electrical signal for 10 seconds. After opening the window to 60°, the relative resistance change remains stable at 11000% for 10 seconds. Rapid open / close monitoring is then performed, with the signal changes consistent with the initial state. If the conductive fluorescent hydrogel is connected to an alarm, an alarm will sound when the window is opened for longer than a specified time, indicating that the window has been open for too long in winter, affecting the indoor temperature. This opens up new avenues for the application of conductive fluorescent hydrogels.

[0161] (6) NH3 detection of hydrogel:

[0162] First, a conductive fluorescent hydrogel (initial length of 20 mm) was placed in an atmosphere of varying NH3 concentrations and removed after 1 minute to measure its fluorescence emission spectrum. Using a mold, the hydrogel was fixed at 200% and 400% strain, then placed in an atmosphere of varying NH3 concentrations. After 1 minute, the fluorescence emission spectrum was measured. The limit of detection (LOD) was calculated by linearly fitting the NH3 concentration to the fluorescence intensity.

[0163] Figure 5 These are optical photographs of the conductive fluorescent hydrogel prepared in step 6 of Example 3 at different response times when placed in a 20 ppm NH3 atmosphere at an original length of 20 mm. As can be seen from the figure, the hydrogel gradually brightens under UV light after 1 minute.

[0164] Figure 6Comparison of the fluorescence intensity of the conductive fluorescent hydrogel prepared in step 6 of Example 3 at different times under a 20ppm NH3 atmosphere, with the original length, fixed at 200% strain, and fixed at 400% strain; As can be seen from the bar graph, in the original state, the fluorescence intensity of the hydrogel reaches its peak at 30 minutes. When fixed at 200% strain, the time for the fluorescence intensity of the hydrogel to reach its peak is 24 minutes, which is 6 minutes faster than the 30 minutes required in the original state. When fixed at 400% strain, the time for the fluorescence intensity to reach its peak is 18 minutes, which is 12 minutes and 6 minutes faster than the original state and 200% strain, respectively. This is mainly because the surface area of ​​the hydrogel increases under tension, and the groups inside the hydrogel interact with NH3 faster.

[0165] Figure 7 a) Fluorescence emission spectrum and b) linear fit and detection limit of the relationship between NH3 concentration and fluorescence intensity of the conductive fluorescent hydrogel prepared in step 6 of Example 3 when the original length was placed in a 20 ppm to 500 ppm NH3 atmosphere for 1 min;

[0166] Figure 8 a) Fluorescence emission spectrum and b) linear fit and detection limit of the NH3 concentration vs. fluorescence intensity of the conductive fluorescent hydrogel prepared in step 6 of Example 3, placed in a 200% strain atmosphere with 20 ppm to 500 ppm NH3 for 1 min;

[0167] Figure 9 a) Fluorescence emission spectrum and b) linear fit and detection limit of the NH3 concentration vs. fluorescence intensity of the conductive fluorescent hydrogel prepared in step 6 of Example 3, placed in a 20 ppm to 500 ppm NH3 atmosphere at a fixed strain of 400% for 1 min.

[0168] from Figure 7-9It can be seen from the results that with the increase of NH3 concentration, the intensity of the characteristic peak of the fluorescence emission spectrum gradually increases, and the concentration of NH3 has an obvious linear relationship with the fluorescence intensity of the hydrogel. The detection limit of the original length of the hydrogel is calculated to be 18.24ppm. Then, the strain of the hydrogel is increased to 200% by stretching. From the fluorescence spectrum, it is found that the hydrogel recovers faster than the original fluorescence at 200% strain. It is calculated that the detection limit of the hydrogel at 200% strain is reduced to 15.07ppm. Due to the excellent mechanical properties of the hydrogel, the hydrogel is further stretched to 400% to observe the change in the detection limit of the hydrogel. From the results of the fluorescence spectrum, it can be seen that the hydrogel at 400% strain will reach stability at a lower NH3 concentration, and the detection limit is even lower at 10.89ppm. By utilizing the excellent tensile properties of the hydrogel itself, the gas detection limit is adjustable, so that it can be more accurately applied to the detection of gases in environments with different needs. In the future, the sensitive detection of more gases can be further broadened.

Claims

1. A method for preparing a conductive fluorescent hydrogel with enhanced low-temperature mechanical properties and adjustable gas detection limit, characterized in that It is carried out in the following steps:

1. Mix distilled water and glycerin evenly to obtain a distilled water / glycerin mixed solution; 2. adding sodium lauryl sulfate to the distilled water / glycerol mixed solution and stirring to dissolve to form a transparent solution to obtain a sodium lauryl sulfate solution; 3. Add lauryl methacrylate to the sodium lauryl sulfate solution, stir, and then sonicate until completely dissolved to obtain solution A; 4. Add the fluorescent complex, acrylamide and 2-acrylamide-2-methyl-1-propanesulfonic acid to solution A and stir to obtain solution B; 5. Add potassium persulfate to solution B and stir until completely dissolved to obtain a uniform and transparent solution C; 6. Pour the uniform transparent solution C into a mold and heat to polymerize, thereby completing the preparation method of the conductive fluorescent hydrogel with enhanced low-temperature mechanical properties and adjustable gas detection limit.

2. The method for preparing a conductive fluorescent hydrogel with enhanced low-temperature mechanical properties and adjustable gas detection limit according to claim 1, characterized in that The volume ratio of distilled water to glycerol described in step 1 is (1-10):

1.

3. The method for preparing a conductive fluorescent hydrogel with enhanced low-temperature mechanical properties and adjustable gas detection limit according to claim 1, characterized in that The molar ratio of the sodium lauryl sulfate described in step 2 to the distilled water / glycerol mixed solution is 1 mmol: (8.5-20) mL; in step 2, sodium lauryl sulfate is added to the distilled water / glycerol mixed solution at a temperature of 0°C to 50°C and a stirring speed of 200 rpm to 1000 rpm, and stirred for 0.5 h to 4 h to dissolve to form a transparent solution, thereby obtaining a sodium lauryl sulfate solution.

4. The method for preparing a conductive fluorescent hydrogel with enhanced low-temperature mechanical properties and adjustable gas detection limit according to claim 1, characterized in that In step 3, lauryl methacrylate is added to the sodium dodecyl sulfate solution and stirred for 10 min to 30 min at a temperature of 20° C. to 50° C. and a stirring speed of 200 rpm to 1000 rpm; the ultrasonication in step 3 is specifically performed at a temperature of 20° C. to 50° C. and an ultrasonic power of 200 W to 300 W for 30 min to 60 min until complete dissolution; the molar ratio of lauryl methacrylate in step 3 to sodium dodecyl sulfate in step 2 is 1:(2 to 10).

5. The method for preparing a conductive fluorescent hydrogel with enhanced low-temperature mechanical properties and adjustable gas detection limit according to claim 1, characterized in that The fluorescent complex described in step 4 is specifically prepared according to the following steps: ① Dissolving a lanthanide metal salt in distilled water at a heating temperature of 80° C. to 100° C. and a stirring speed of 200 rpm to 1000 rpm to obtain a lanthanide metal salt solution; the concentration of the lanthanide metal salt in the lanthanide metal salt solution is 0.01 mol / L to 0.05 mol / L; ② Dissolving 2,6-pyridinedicarboxylic acid in distilled water at a heating temperature of 80° C. to 100° C. and a stirring speed of 200 rpm to 1000 rpm to obtain a 2,6-pyridinedicarboxylic acid solution; the concentration of 2,6-pyridinedicarboxylic acid in the 2,6-pyridinedicarboxylic acid solution is 0.05 mol / L to 0.15 mol / L; ③ Add the lanthanide metal salt solution to the 2,6-pyridinedicarboxylic acid solution, then heat it to 100°C~120°C, and stir it for 1h~2h at a temperature of 100°C~120°C and a stirring speed of 200rpm~1000rpm to obtain a white turbid solution, and finally filter and repeatedly wash it with distilled water to obtain a white solid, i.e., Ln(PDA)3 fluorescent complex; the molar ratio of the lanthanide metal salt in the lanthanide metal salt solution to the 2,6-pyridinedicarboxylic acid in the 2,6-pyridinedicarboxylic acid solution is 1:(0.4~37.5).

6. The method for preparing a conductive fluorescent hydrogel with enhanced low-temperature mechanical properties and adjustable gas detection limit according to claim 5, characterized in that The lanthanide metal salt in step ① is europium chloride, europium nitrate, terbium chloride or terbium nitrate.

7. The method for preparing a conductive fluorescent hydrogel with enhanced low-temperature mechanical properties and adjustable gas detection limit according to claim 1, characterized in that The molar ratio of the mass of the fluorescent complex described in step 4 to acrylamide is 1 mg:(0.5-15) mmol; the molar ratio of acrylamide described in step 4 to 2-acrylamide-2-methyl-1-propanesulfonic acid is 1:(0-0.8); the molar ratio of the mass of the fluorescent complex described in step 4 to lauryl methacrylate in step 3 is 1 mg:(0.0035-0.075) mmol; in step 4, the fluorescent complex, acrylamide and 2-acrylamide-2-methyl-1-propanesulfonic acid are added to solution A at a temperature of 0° C. to 50° C. and a stirring speed of 200 rpm to 1000 rpm and stirred for 10 min to 30 min.

8. The method for preparing a conductive fluorescent hydrogel with enhanced low-temperature mechanical properties and adjustable gas detection limit according to claim 1, characterized in that The molar ratio of potassium persulfate in step 5 to acrylamide in step 4 is 1:(50-600); in step 5, potassium persulfate is added to solution B at a temperature of 0°C to 50°C and a stirring speed of 200 rpm to 1000 rpm and stirred for 10 min to 30 min until completely dissolved.

9. The method for preparing a conductive fluorescent hydrogel with enhanced low-temperature mechanical properties and adjustable gas detection limit according to claim 1, characterized in that The polymerization reaction in step six is ​​specifically carried out at a heating temperature of 50° C. to 80° C. for 1 h to 5 h.

10. Use of a conductive fluorescent hydrogel with enhanced low-temperature mechanical properties and adjustable gas detection limit prepared as claimed in claim 1, characterized in that It is used for winter window opening / closing monitoring or NH3 detection.

Images