A hydrogen bond heterojunction polymer, preparation method and nitrogen dioxide resistance sensor

Abstract

The application relates to a hydrogen bond heterojunction polymer, a preparation method and a nitrogen dioxide resistance sensor, and belongs to the technical field of organic semiconductor devices. The polymer is formed into a heterojunction structure through hydrogen bond interaction of a squaric acid amide polymer and a metal coordination polymer. When the polymer is contacted with nitrogen dioxide molecules, more charge transfer can be generated, and the sensitivity of the hydrogen bond heterojunction polymer is increased. The polymer is used in a nitrogen dioxide resistance sensor, the device has a low detection limit, and can realize ppb-level nitrogen dioxide detection. The polymer preparation method is simple in operation and easy to industrialize.

Description

Technical Field

[0001] The invention relates to a hydrogen bond heterojunction polymer, a preparation method and a nitrogen dioxide resistance sensor, and belongs to the technical field of organic semiconductor devices. Background Art

[0002] Nitrogen oxides are one of the three major components of haze in the air, including nitrogen pentoxide, nitrogen dioxide (NO2), and nitric oxide. Among them, nitrogen oxide pollutants in the atmosphere mainly refer to NO and NO2, collectively referred to as NO x , its sources can be divided into natural sources and anthropogenic sources. Natural sources are mainly produced by nitrogen-fixing bacteria and lightning; anthropogenic sources can be divided into fixed nitrogen oxide sources produced by enterprises through the combustion of fossil energy and mobile sources of nitrogen oxides emitted by vehicles at low altitudes. It has the characteristics of high pollution intensity, wide pollution range, and concentrated emission area. NO2 will form acid rain with SO2 and dust, leading to ozone hole. NO2 contained in the ash formed by photochemical smog will also participate in PM 2.5 The formation of NO2. As a colorless gas with a pungent odor, NO2 is harmful to the human body even at low concentrations. Inhalation of NO2 will cause mild eye and upper respiratory tract irritation symptoms, such as throat discomfort and dry cough. When the concentration exceeds 1ppm, it will pose a threat to the human respiratory system. Long-term exposure to ppm-level NO2 environment can cause respiratory diseases such as bronchitis, difficulty breathing, emphysema and even heart disease. Delayed obstructive bronchiolitis may occur about two weeks after the emphysema subsides. In addition, NO2 is also a major environmental pollutant, which can cause acid rain and photochemical smog, trigger surface water acidification, lead to eutrophication of water bodies (due to the rich nutrients such as nitrogen and phosphorus in the water, the massive reproduction of algae leads to hypoxia), and increase the content of toxins in the water that are harmful to fish and other aquatic organisms.

[0003] Organic chemiresistor (OCR) has attracted considerable attention due to its designable structure and low cost. High sensitivity, specific selectivity, reversible reaction / recovery, and other robustness metrics are key to evaluating sensory performance. Although squaraine amide polymers can detect nitrogen dioxide at concentrations as low as 60 ppb (parts per billion), their sensitivity and detection limit still need to be further improved. Summary of the Invention

[0004] In view of this, an object of the present invention is to provide a hydrogen bond heterojunction polymer, a preparation method and a nitrogen dioxide resistive sensor.

[0005] To achieve the above objectives, the technical solutions of the present invention are as follows.

[0006] A hydrogen bond heterojunction polymer, wherein the polymer is formed by hydrogen bonding between a squarylamide polymer and a metal coordination polymer to form a heterojunction structure, and the structural formula of the polymer is:

[0007] Wherein, n is a positive integer.

[0008] Preferably, the molar ratio of the squarylamide polymer to the metal coordination polymer is 0.5 to 2:1.

[0009] A method for preparing the hydrogen-bonded heterojunction polymer of the present invention comprises the following steps:

[0010] (1) Under a protective gas (nitrogen or inert gas) atmosphere, p-phenylenediamine and diethyl squarate are heated to react in a reaction solvent to obtain a crude product, which is purified to obtain a squarylamide polymer powder;

[0011] (2) Add concentrated aqueous ammonia to an aqueous solution of 1,2,4,5-tetraaminobenzene hydrochloride at 0-5°C until the reaction system is neutral, then add an aqueous solution of nickel chloride to react to obtain a metal coordination polymer solution; add squarylamide polymer powder to the metal coordination polymer solution, react, filter, and vacuum dry to obtain a hydrogen bond heterojunction polymer.

[0012] Preferably, in step (1), the molar ratio of p-phenylenediamine, diethyl squarate and reaction solvent is 1:1:100-300.

[0013] Preferably, in step (1), the reaction solvent is a mixed solution of toluene and chloroform in a volume ratio of 1:1, or a mixed solution of toluene and acetonitrile in a volume ratio of 1:1.

[0014] Preferably, in step (1), the reaction temperature is 90-130° C., and the reaction time is 9-16 h.

[0015] Preferably, in step (1), during purification, the crude product is added to an extraction solvent, heated and stirred at 70-90° C. for 24-48 hours under a protective gas (nitrogen or inert gas) atmosphere, naturally cooled, filtered, and vacuum dried at 60-90° C. to obtain a squarylamide polymer powder.

[0016] Preferably, in step (2), the concentrations of the aqueous solution of 1,2,4,5-tetraaminobenzene hydrochloride and the aqueous solution of nickel chloride are 0.01 to 1 mol / L, respectively.

[0017] Preferably, in step (2), the molar ratio of 1,2,4,5-tetraaminobenzene hydrochloride, nickel chloride and squaramide polymer is 1:1:0.5-2.

[0018] Preferably, in step (2), the reaction time is 9 to 16 hours.

[0019] Preferably, in step (2), the vacuum drying temperature is 60-90°C.

[0020] A nitrogen dioxide resistive sensor, wherein the interdigital electrodes of the sensor are coated with the hydrogen bond heterojunction polymer described in the present invention.

[0021] Preferably, the sensor is prepared by the following method, which includes the following steps:

[0022] (1) ultrasonically dispersing the hydrogen-bonded heterojunction polymer in a solvent to obtain a dispersion; the mass ratio of the hydrogen-bonded heterojunction polymer to the solvent is 1:400-600; and the ultrasonic time is 2-10 minutes;

[0023] (2) The dispersion is brushed onto a clean interdigital electrode, and after the solvent is naturally evaporated and removed, it is dried to obtain a nitrogen dioxide resistive sensor.

[0024] Preferably, the solvent is one or more of ethanol, chloroform, and acetone, more preferably chloroform.

[0025] Preferably, the brushing is completed with a brush pen, and the brushing number is 5 to 10 times. After each brushing, the surface is dried and then brushed again; the interdigital electrode includes an aluminum oxide substrate and a silver-palladium alloy electrode, the interdigital width is 50 to 100 μm, the interdigital spacing is 200 to 300 μm, the aluminum oxide substrate thickness is 1 to 2 mm, and the silver-palladium alloy electrode thickness is 100 to 200 nm; the drying temperature is 50 to 80°C, and the drying time is 0.5 to 2 hours.

[0026] Beneficial effects

[0027] The present invention provides a hydrogen-bonded heterojunction polymer. A squarylamide polymer and a metal coordination polymer form a heterojunction structure through hydrogen bonding. This polymer can generate more charge transfer when in contact with nitrogen dioxide molecules, thereby increasing the sensitivity of the hydrogen-bonded heterojunction polymer. This polymer can be used in a nitrogen dioxide resistive sensor, resulting in a low device detection limit and capable of detecting nitrogen dioxide at the ppb level. The polymer preparation method is simple to operate and is readily industrializable. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is the infrared spectrum result of the hydrogen bond heterojunction polymer described in Example 1.

[0029] Figure 2 This is the response test result of the sensor device in Example 1.

[0030] Figure 3 The performance comparison results of the sensor device in Example 1 are shown. DETAILED DESCRIPTION

[0031] The application will be further described in conjunction with specific examples.

[0032] Example 1

[0033] Synthesis of hydrogen-bonded hetero-junction polymer:

[0034] P-phenylenediamine (0.55 g, 5 mmol), diethyl squarate (0.85 g, 5 mmol), toluene (46.1 g, 0.5 mol) and acetonitrile (20.5 g, 0.5 mol) were weighed into a single-necked pressure-resistant flask, which was loaded with a reflux device. The air in the reaction system was replaced with nitrogen four times. Then the temperature was raised to 125°C, and the stirring device was turned on. The reaction was refluxed for 12 h. After the reaction was completed, the temperature was reduced to room temperature. The product was filtered and dried in a vacuum oven at 70°C to obtain orange powder of the crude product. Then the crude product was purified by a Soxhlet extractor. Tetrahydrofuran was selected as the extraction agent. The crude product was loaded into the Soxhlet extractor, and the air in the reaction system was replaced with nitrogen four times. The temperature was raised to 65°C, and the stirring device was turned on. The reaction was refluxed for 36 h. After the temperature was reduced to room temperature, the product was filtered and dried in a vacuum oven at 65°C to obtain 0.76 g of orange powder of the squaric acid amide polymer.

[0035] 1,2,4,5-tetraaminobenzene hydrochloride (0.28 g, 1 mmol), nickel chloride (0.13 g, 1 mmol), and squaric acid amide polymer (0.19 g, 1 mmol) were weighed. The 1,2,4,5-tetraaminobenzene hydrochloride and the squaric acid amide polymer were dissolved in 10 ml of pure water, respectively, and placed in a low-temperature reaction tank to be cooled to 0°C. Concentrated ammonia water (12 M / L) was slowly added dropwise to the 1,2,4,5-tetraaminobenzene hydrochloride solution until the reaction system was neutral. Then the nickel chloride solution was slowly added, and the reaction was carried out at room temperature for 10 h to obtain a metal complex polymer solution. Finally, the squaric acid amide polymer was added, and the stirring reaction was continued at room temperature for 12 h. After the reaction was completed, the product was filtered and dried in a vacuum oven at 70°C to obtain a hydrogen-bonded hetero-junction polymer powder.

[0036] The infrared spectrum of the hydrogen-bonded hetero-junction polymer is shown in Figure 1 The results show that, compared with the squaric acid amide polymer and the complex polymer, the hydrogen-bonded hetero-junction polymer has a red shift or a blue shift of some functional groups, which proves the existence of hydrogen bond interaction.

[0037] Preparation of the sensor:

[0038] (1) The interdigital electrode was sequentially ultrasonically cleaned with 10 ml of water, ethanol and acetone, respectively, and was dried for standby use.

[0039] (2) 4 mg of hydrogen-bonded hetero-junction polymer was added into 2 g of chloroform and ultrasonically dispersed for 5 min to obtain a dispersion liquid containing hydrogen-bonded hetero-junction polymer;

[0040] (3) The dispersion liquid was brush-coated on the interdigital electrode, and the brush-coating was repeated 8 times. After each brush-coating, the surface was dried before the next brush-coating. After the brush-coating, the device was placed at room temperature until it was dried, and then placed in an oven at 60 °C for 1 h to obtain a nitrogen dioxide resistance sensor based on hydrogen-bonded hetero-junction polymer with a film thickness of 300 μm.

[0041] Current response determination of the sensor under different concentrations of nitrogen dioxide:

[0042] First, the device was placed in pure nitrogen gas, and the current was stabilized. Then, the device was placed in an atmosphere of nitrogen dioxide gas with different concentrations. After the current was stabilized, the device was again placed in pure nitrogen gas. The above cycle was repeated, and the results are shown in FIGS. 1 and 2. Figure 2 and Figure 3 As can be seen from the figures, the sensor based on hydrogen-bonded hetero-junction polymer has good response and recovery performance to as low as 10 ppb of nitrogen dioxide, and the response value is larger than that of squaraine amide polymer and metal coordination polymer.

[0043] Example 2

[0044] Synthesis of hydrogen-bonded hetero-junction polymer:

[0045] P-phenylenediamine (0.11 g, 1 mmol), squaric acid diethyl ester (0.17 g, 1 mmol), toluene (46.1 g, 0.5 mol), and acetonitrile (20.5 g, 0.5 mol) were weighed into a single-mouth pressure-resistant bottle, and a reflux device was loaded. The air in the reaction system was replaced with nitrogen four times. Then, the temperature was raised to 125 °C, and the stirring device was turned on. The reaction was refluxed for 12 h. After the reaction was completed, the temperature was lowered to room temperature, and the product was filtered and dried in a vacuum oven at 70 °C to obtain an orange powder of the crude product. Then, the crude product was purified by a Soxhlet extractor, and tetrahydrofuran was selected as the extraction agent. The crude product was loaded into the Soxhlet extractor, and the air in the reaction system was replaced with nitrogen four times. The temperature was raised to 65 °C, and the stirring device was turned on. The reaction was refluxed for 36 h. After the temperature was lowered to room temperature, the product was filtered and dried in a vacuum oven at 65 °C to obtain an orange powder of squaraine amide polymer.

[0046] Weigh 1,2,4,5-tetraaminobenzene hydrochloride (0.56 g, 2 mmol), nickel chloride (0.26 g, 2 mmol), and a squarylamide polymer (0.19 g, 1 mmol). Dissolve the 1,2,4,5-tetraaminobenzene hydrochloride and nickel chloride in 15 ml of pure water, then cool to 0°C in a low-temperature reaction tank. Slowly add concentrated ammonia (12 M / L) dropwise to the 1,2,4,5-tetraaminobenzene hydrochloride solution until the reaction system is neutral. Then, slowly add nickel chloride solution and react at room temperature for 10 hours to obtain a metal coordination polymer solution. Finally, add the squarylamide polymer and continue stirring at room temperature for 12 hours. After the reaction is complete, filter and dry in vacuo at 70°C to obtain a hydrogen-bonded heterojunction polymer powder.

[0047] The infrared spectrum results of the hydrogen-bonded heterojunction polymer show that compared with the squarylamide polymer and the coordination polymer, some functional groups of the hydrogen-bonded heterojunction polymer undergo red-shift or blue-shift, proving the existence of hydrogen-bonding interaction.

[0048] Preparation of the sensor:

[0049] (1) Ultrasonic cleaning of the interdigital electrodes was performed using 10 ml of water, ethanol, and acetone in order, and the electrodes were dried and then used for later use;

[0050] (2) ultrasonically adding 4 mg of hydrogen-bonded heterojunction polymer to 2 g of ethanol and ultrasonically dispersing for 5 minutes to obtain a dispersion containing the hydrogen-bonded heterojunction polymer;

[0051] (3) The dispersion was brush-coated on the interdigitated electrodes eight times, and the surface was allowed to dry before being brushed again. After the coating was completed, the surface was left at room temperature, and after evaporation, it was placed in an oven at 70°C and dried for 1 hour to obtain a nitrogen dioxide resistive sensor based on a hydrogen-bonded heterojunction polymer with a film thickness of 300 μm.

[0052] The current response of the sensor under different concentrations of nitrogen dioxide is measured:

[0053] The device was first placed in pure nitrogen, and after the current stabilized, it was then placed in atmospheres with varying concentrations of nitrogen dioxide. Once the current stabilized, the device was placed back in pure nitrogen, and the cycle repeated. The results showed that the sensor exhibited good response and recovery performance to nitrogen dioxide concentrations as low as 10 ppb, and its response values ​​were greater than those of squaramide polymers and metal coordination polymers.

[0054] Example 3

[0055] Synthesis of Hydrogen Bonded Heterojunction Polymers:

[0056] p-Phenylenediamine (0.55 g, 5 mmol), diethyl squarate (0.85 g, 5 mmol), toluene (46.1 g, 0.5 mol), and acetonitrile (20.5 g, 0.5 mol) were weighed and placed in a single-necked pressure flask. After installing a reflux device, the air in the reaction system was replaced with nitrogen four times. The temperature was then raised to 125°C, stirring was initiated, and the reaction was refluxed for 12 hours. After the reaction was complete, the temperature was cooled to room temperature, the product was filtered, and dried in a vacuum oven at 70°C to obtain a crude orange powder. The crude product was then purified using a Soxhlet extractor with tetrahydrofuran as the extractant. After the crude product was placed in the Soxhlet extractor, the air in the reaction system was replaced with nitrogen four times. The temperature was then raised to 65°C, stirring was initiated, and the reaction was refluxed for 36 hours. After cooling to room temperature, the product was filtered and dried in a vacuum oven at 65°C to obtain an orange powder of squaramide polymer.

[0057] Weigh a specific molar ratio of 1,2,4,5-tetraaminobenzene hydrochloride (0.28 g, 1 mmol), nickel chloride (0.13 g, 1 mmol), and squarylamide polymer (0.38 g, 2 mmol). Dissolve 1,2,4,5-tetraaminobenzene hydrochloride and nickel chloride in 10 ml of pure water, then cool to 0°C in a low-temperature reaction tank. Slowly add concentrated ammonia (12 M / L) dropwise to the 1,2,4,5-tetraaminobenzene hydrochloride solution until the reaction system is neutral. Then, slowly add nickel chloride solution and react at room temperature for 10 hours. Finally, add the squarylamide polymer and continue stirring at room temperature for 12 hours. After completion of the reaction, filter and dry in vacuo at 70°C to obtain hydrogen-bonded heterojunction polymer powder.

[0058] (2) Preparation of sensor:

[0059] Step 1: ultrasonically clean the interdigital electrodes using 10 ml of water, ethanol, and acetone in order, and then dry them for later use;

[0060] Step 2: ultrasonically add 4 mg of hydrogen-bonded heterojunction polymer to 2 g of acetone, and ultrasonically disperse for 5 minutes to obtain a simulated dispersion containing the hydrogen-bonded heterojunction polymer;

[0061] Step 3: Apply the dispersion to the interdigitated electrodes eight times, allowing the surface to dry before applying again. After application, allow the dispersion to stand at room temperature until the vapor evaporates and then dry in an oven at 60°C for 1 hour, resulting in a 300 μm-thick hydrogen-bonded heterojunction polymer sensor.

[0062] (3) Current response measurement of nitrogen dioxide sensor based on hydrogen bond heterojunction polymer at different concentrations of nitrogen dioxide:

[0063] The device was first placed in pure nitrogen, and after the current stabilized, it was then placed in atmospheres with varying concentrations of nitrogen dioxide. Once the current stabilized, the device was placed in pure nitrogen again, and the cycle was repeated. The hydrogen-bonded heterojunction polymer-based sensor exhibited excellent response and recovery performance to nitrogen dioxide concentrations as low as 10 ppb, and its response value was even greater than that of squaramide polymers and metal coordination polymers.

[0064] In summary, the invention includes but is not limited to the above embodiments. Any equivalent replacement or partial improvement made under the spirit and principle of the present invention shall be deemed to be within the scope of protection of the present invention.

Claims

1. A method for preparing a hydrogen-bonded heterojunction polymer, characterized in that: The method steps include: (1) Under a protective gas atmosphere, p-phenylenediamine and diethyl squarate are heated to react in a reaction solvent to obtain a crude product, which is then purified to obtain a squaramide polymer powder; (2) Add concentrated aqueous ammonia to an aqueous solution of 1,2,4,5-tetraaminobenzene hydrochloride at 0-5°C until the reaction system is neutral, then add an aqueous solution of nickel chloride to react to obtain a metal coordination polymer solution; add squarylamide polymer powder to the metal coordination polymer solution, react, filter, and vacuum dry to obtain a hydrogen bond heterojunction polymer.

2. The method for preparing a hydrogen-bonded heterojunction polymer according to claim 1, wherein: In step (1), the molar ratio of p-phenylenediamine, diethyl squarate and reaction solvent is 1:1:100-300; The reaction solvent is a mixed solution of toluene and chloroform in a volume ratio of 1:1, or a mixed solution of toluene and acetonitrile in a volume ratio of 1:1; The reaction temperature is 90~130℃, and the reaction time is 9~16h.

3. The method for preparing a hydrogen-bonded heterojunction polymer according to claim 1 or 2, wherein: In step (1), during purification, the crude product is added to an extraction solvent, heated and stirred at 70-90° C. for 24-48 hours under a protective gas atmosphere, naturally cooled, filtered, and vacuum-dried at 60-90° C. to obtain a squaramide polymer powder.

4. The method for preparing a hydrogen-bonded heterojunction polymer according to claim 1, wherein: In step (2), the concentrations of the aqueous solution of 1,2,4,5-tetraaminobenzene hydrochloride and the aqueous solution of nickel chloride are 0.01 to 1 mol / L, respectively.

5. The method for preparing a hydrogen-bonded heterojunction polymer according to claim 1 or 4, wherein: In step (2), the molar ratio of 1,2,4,5-tetraaminobenzene hydrochloride, nickel chloride and squaramide polymer is 1:1:0.5~2.

6. The method for preparing a hydrogen-bonded heterojunction polymer according to claim 5, wherein: In step (2), the reaction time is 9 to 16 hours; and the vacuum drying temperature is 60 to 90°C.

7. A hydrogen-bonded heterojunction polymer, characterized in that: It is prepared by the method according to any one of claims 1 to 6.

8. A nitrogen dioxide resistance sensor, characterized in that: The interdigital electrodes of the sensor are coated with the hydrogen-bonding heterojunction polymer according to claim 7.

9. The nitrogen dioxide resistance sensor according to claim 8, characterized in that: The sensor is prepared by the following method, which includes the following steps: (1) ultrasonically dispersing the hydrogen-bonded heterojunction polymer in a solvent to obtain a dispersion; the mass ratio of the hydrogen-bonded heterojunction polymer to the solvent is 1:400-600; and the ultrasonication time is 2-10 minutes; (2) The dispersion is brushed onto a clean interdigital electrode, and after the solvent is naturally evaporated and removed, it is dried to obtain a nitrogen dioxide resistive sensor.

10. The nitrogen dioxide resistance sensor according to claim 9, characterized in that: The solvent is one or more of ethanol, chloroform and acetone.

11. The nitrogen dioxide resistance sensor according to claim 9, wherein: The brushing is completed with a brush pen, and the number of brushing times is 5 to 10. After each brushing, the surface is dried and then brushed again. The interdigital electrode includes an aluminum oxide substrate and a silver-palladium alloy electrode. The interdigital width is 50 to 100 μm, the interdigital spacing is 200 to 300 μm, the aluminum oxide substrate thickness is 1 to 2 mm, and the silver-palladium alloy electrode thickness is 100 to 200 nm. The drying temperature is 50 to 80°C, and the drying time is 0.5 to 2 hours.

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