Protonated croconic acid cyanine polymer, preparation method and low-humidity resistance-type sensor

Abstract

The invention relates to a protonated croconic acid cyanine polymer, a preparation method and a low-humidity resistive sensor, and belongs to the technical field of organic semiconductor devices. The structural formula of the polymer is # imgabs0 #, n is a positive integer, X is hydrogen or deuterium, and A <-> is Cl <->, HSO4 <-> and H2PO4 <->. The polymer can form a more complete hydrogen bond network under low humidity, so that the sensitivity of the polymer under low humidity is increased; the response in a wide humidity range of 11%-95% is maintained, and the sensitivity in a low humidity range (11%-33% RH) is improved; in addition, ions introduced by protonation can generate anion-pi interaction with a pi conjugated system, so that the stability of the polymer is improved.

Description

Technical Field

[0001] The invention relates to a protonated crotonyl cyanine polymer, a preparation method and a low-humidity resistive sensor, and belongs to the technical field of organic semiconductor devices. Background Art

[0002] With the acceleration of industrialization and modernization, accurate monitoring of environmental humidity has become crucial in many fields. Humidity not only affects people's daily lives, but also plays an important role in many fields such as agriculture, industrial production, warehouse management, health care, building maintenance, and scientific research. In these fields, accurate detection of low humidity environments is particularly important because low humidity conditions may have a significant impact on product quality, human health, and environmental stability. In low humidity environments, traditional humidity sensors face problems such as long response time, low accuracy, and susceptibility to environmental interference. In addition, such sensors usually perform well in high humidity environments, but their accuracy and stability are insufficient in low humidity environments, such as deserts, dry laboratories, or special industrial environments. Therefore, the development of a humidity detection technology that can work stably and with high sensitivity in low humidity environments is of great significance to improving the work efficiency and safety of related fields.

[0003] With the development of materials science, organic polymers have gradually become a research hotspot in the field of humidity detection due to their unique physical and chemical properties, such as good environmental adaptability, adjustable sensitivity, excellent mechanical properties and cost-effectiveness. Organic polymer humidity sensors have shown great application potential with their advantages such as fast response, high sensitivity, good stability and low cost. For example, polypyrrole composites have been used to design and manufacture fast-response, highly sensitive and economical resistive humidity detection sensors (Polymers, 2021, 13, 3019.). However, existing organic polymers such as oxadiazine polymers still have problems with low sensitivity and poor stability in humidity detection technology. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a protonated crotonyl cyanine polymer, a preparation method and a low-humidity resistive sensor.

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

[0006] A protonated cyanine polymer, the structural formula of the polymer is:

[0007] Where n is a positive integer, X is hydrogen or deuterium, A - Cl - , HSO 4 - , H 2PO 4 - .

[0008] A method for preparing the protonated crotonate cyanine polymer of the present invention comprises the following steps:

[0009] (1) Under a protective gas (nitrogen or inert gas) atmosphere, p-phenylenediamine and crotonyl cyanide are heated in a reaction solvent to react to obtain a crude product, which is purified to obtain a crotonyl cyanide polymer powder;

[0010] (2) mixing the crotonyl cyanine polymer powder and a proton source, heating and ultrasonically reacting the mixture, centrifuging the mixture after the reaction is complete, washing the solid, and vacuum drying the mixture to obtain a protonated crotonyl cyanine polymer;

[0011] Wherein, the proton source is hydrochloric acid, sulfuric acid, phosphoric acid, deuterated hydrochloric acid, deuterated sulfuric acid or deuterated phosphoric acid.

[0012] Preferably, in step (1), the molar ratio of p-phenylenediamine, crotonic acid 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 to 90° C. for 24 to 48 hours under a protective gas (nitrogen or inert gas) atmosphere, naturally cooled, filtered, and vacuum dried at 60 to 90° C. to obtain a crotonyl cyanine polymer powder.

[0016] Preferably, in step (2), the concentration of the proton source is 1 to 2 mol / L.

[0017] Preferably, in step (2), the molar ratio of the crotonyl cyanine polymer to the proton source is 1:3-10.

[0018] Preferably, in step (2), the ultrasonic temperature is 20 to 60° C., and the ultrasonic time is 10 to 60 min.

[0019] Preferably, in step (2), the centrifugal speed is 8000-13000 r / min, and the centrifugal time is 30-60 min.

[0020] Preferably, in step (2), the vacuum drying temperature is 60 to 90°C.

[0021] A low-humidity resistive sensor, wherein the interdigitated electrodes of the sensor are coated with the protonated crotonate cyanine polymer of the present invention.

[0022] Preferably, the sensor is prepared by the following method, the method steps comprising:

[0023] (1) ultrasonically dispersing the protonated crotonyl cyanine 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;

[0024] (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 low-humidity resistive sensor.

[0025] Preferably, the solvent is one or more of ethanol, chloroform and acetone, more preferably chloroform.

[0026] Preferably, the brushing is completed with a brush pen, the brushing times are 5 to 10 times, and the surface is brushed again after each brushing. 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.

[0027] Beneficial Effects

[0028] The present invention provides a protonated crotonyl cyanine polymer, which can form a more complete hydrogen bond network at low humidity, so that its sensitivity at low humidity is increased; in addition to maintaining the response in a wide humidity range of 11% to 95%, its sensitivity in a low humidity range (11% to 33% RH) is improved; the polymer is used in a humidity sensor, and its sensitivity (up to five orders of magnitude change) and detection humidity range (11-95% RH) have significant advantages. In addition, the ions introduced by protonation can interact with the π conjugated system by anions-π, thereby increasing the stability of the polymer. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The infrared spectrum of the polymer described in Example 1 is shown in FIG.

[0030] Figure 2 The solid state NMR results of the polymer described in Example 1 are shown in FIG.

[0031] Figure 3 The performance test results of the sensor device described in Example 1 are shown in FIG.

[0032] Figure 4The stability test results of the sensor device described in Example 1. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below in conjunction with specific embodiments.

[0034] Example 1

[0035] (1) Synthesis of protonated cyanine polymers

[0036] Weigh p-phenylenediamine (0.56g, 5mmol), diethyl squarate (0.85g, 5mmol), toluene (46.1g, 0.5mol) and acetonitrile (20.5g, 0.5mol) and place them in a single-mouth pressure-resistant bottle. After loading the reflux device, replace the air in the reaction system with nitrogen four times. Then heat it to 125℃, turn on the stirring device, and reflux for 12h. After the reaction is complete, wait for the temperature to drop to room temperature, filter the product and dry it in a vacuum oven at 70℃ to obtain a black powder crude product. Then use a Soxhlet extractor to purify the obtained crude product, and the selected extractant is tetrahydrofuran. After the crude product is loaded into the Soxhlet extractor, replace the air in the reaction system with nitrogen four times. Heat it to 65℃, turn on the stirring device, and reflux for 36h. When the temperature drops to room temperature, filter the product and dry it in a vacuum oven at 65℃ to obtain 1.16g of black powder of crotonyl cyanine polymer.

[0037] Weigh the black powder of oxadiazine polymer (1 mmol, 214 mg) and proton source hydrochloric acid (1 mol / L, 5 mL) and place them in a single-mouth pressure-resistant bottle equipped with a condensing device, then place it in an ultrasonic reactor for ultrasonic reaction at 25°C for 30 minutes. After the reaction, use an ultra-high speed machine to centrifuge at a speed of 12000 r / min for 20 minutes to separate the solid, and then wash it repeatedly with ultrapure water for 3 times. Finally, place it in a vacuum oven at 70°C and dry it to obtain the protonated oxadiazine polymer black powder.

[0038] The infrared spectrum results of the polymer are as follows Figure 1 As shown, the results show that the carbonyl absorption peaks of the raw material keto acid and the product have shifted, proving the occurrence of the polymerization reaction. The solid NMR results of the polymer are as follows Figure 2 As shown, the results show that the spectrum results correspond one-to-one with the chemical environment of carbon in the structure.

[0039] (2) Preparation of sensor:

[0040] Step 1: Use 10 ml of water, ethanol and acetone to ultrasonically clean the interdigital electrodes in order, and then dry them for later use;

[0041] Step 2, adding 4 mg of protonated cyanine polymer to 2 g of chloroform by ultrasonication, and ultrasonically dispersing for 5 minutes to obtain a dispersion containing the protonated cyanine polymer;

[0042] Step 3: Apply the dispersion on the interdigital electrodes 8 times, and apply again after the surface is dry after each application. After application, place it at room temperature, and after the solvent evaporates, place it in an oven at 60°C for 1 hour to obtain a humidity resistive sensor based on protonated polymer with a film thickness of 300 μm.

[0043] (3) Determination of the response of protonated cyanine polymer to different humidity:

[0044] First, place the sensor device in an atmosphere containing color-changing silica gel. After the current stabilizes, place the device in an atmosphere of saturated solutions of different metal salts. After the current stabilizes, place the device in an atmosphere of color-changing silica gel again. Repeat the above cycle. The results are as follows: Figure 3 As shown in the figure, it can be seen that the protonated crotonyl cyanine polymer can achieve humidity detection in the range of 11% to 95% RH, and its response value to low humidity is greater than that of the polymer before protonation. The stability test results of the device are shown in Figure 4 As shown, the results indicate that the anion-π conjugation effect increases the stability of the protonated polymer.

[0045] Example 2

[0046] (1) Synthesis of protonated cyanine polymers

[0047] Weigh p-phenylenediamine (1.08g, 10mmol), keto acid (1.42g, 10mmol), toluene (92.2g, 1mol) and tetrahydrofuran (41g, 1mol) and place them in a single-mouth pressure-resistant bottle. After loading the reflux device, replace the air in the reaction system with nitrogen four times. Then heat it to 115℃, turn on the stirring device, and reflux for 16h. After the reaction is complete, wait for the temperature to drop to room temperature, filter the product and dry it in a vacuum oven at 80℃ to obtain a black powder crude product. Then use a Soxhlet extractor to purify the obtained crude product, and the selected extractant is tetrahydrofuran. After the crude product is loaded into the Soxhlet extractor, replace the air in the reaction system with nitrogen four times. Heat it to 70℃, turn on the stirring device, and reflux for 36h. When the temperature drops to room temperature, filter the product and dry it in a vacuum oven at 70℃ to obtain 1.76g of black powder of keto acid cyanine polymer.

[0048] Weigh the black powder of oxadiazine polymer (2 mmol, 428 mg) and proton source phosphoric acid (1 mol / L, 10 mL) and place them in a single-mouth pressure-resistant bottle equipped with a condensing device, then place it in an ultrasonic reactor for ultrasonic reaction at 35°C for 20 minutes. After the reaction, use an ultra-high speed machine to centrifuge at a speed of 10000 r / min for 30 minutes to separate the solid, and then wash it repeatedly with ultrapure water for 3 times. Finally, place it in a vacuum oven at 80°C and dry it to obtain the protonated black powder of oxadiazine polymer.

[0049] (2) Preparation of sensor:

[0050] Step 1: Use 10 ml of water, ethanol and acetone to ultrasonically clean the interdigital electrodes in order, and then dry them for later use;

[0051] Step 2: adding 4 mg of protonated cyanine polymer to 2 g of ethanol by ultrasonication, and performing ultrasonic dispersion for 5 minutes to obtain a dispersion containing the protonated cyanine polymer;

[0052] Step 3: Apply the dispersion on the interdigital electrodes 8 times, and apply again after the surface is dry after each application. After application, place at room temperature, and after the solvent evaporates, place in an oven at 70°C for 1 hour to obtain a protonated polymer sensor with a film thickness of 300 μm.

[0053] (3) Determination of the response of protonated cyanine polymer to different humidity:

[0054] First, the device is placed in an atmosphere containing color-changing silica gel. After the current is stable, the device is placed in an atmosphere of saturated solutions of different metal salts. After the current is stable, the device is placed in an atmosphere of color-changing silica gel again. The above cycle is repeated. The results show that the protonated crotonyl cyanine polymer can achieve humidity detection in the range of 11% to 95% RH, and its response value to low humidity is greater than that of the polymer before protonation. The sensor also has good stability.

[0055] Example 3

[0056] (1) Synthesis of protonated cyanine polymers

[0057] Weigh p-phenylenediamine (0.21g, 2mmol), keto acid (0.28g, 2mmol), toluene (23.1g, 0.25mol) and tetrahydrofuran (10.3g, 0.25mol) and place them in a single-mouth pressure-resistant bottle. After loading the reflux device, replace the air in the reaction system with nitrogen four times. Then heat it to 130℃, turn on the stirring device, and reflux for 16h. After the reaction is complete, wait for the temperature to drop to room temperature, filter the product and dry it in a vacuum oven at 60℃ to obtain a black powder crude product. Then use a Soxhlet extractor to purify the obtained crude product, and the selected extractant is tetrahydrofuran. After the crude product is loaded into the Soxhlet extractor, replace the air in the reaction system with nitrogen four times. Heat it to 115℃, turn on the stirring device, and reflux for 36h. After the temperature drops to room temperature, filter the product and dry it in a vacuum oven at 60℃ to obtain 0.36g of black powder of keto acid cyanine polymer.

[0058] Weigh the black powder of oxadiazine polymer (1 mmol, 214 mg) and proton source hydrochloric acid (1 mol / L, 8 mL) and place them in a single-mouth pressure-resistant bottle equipped with a condensing device, then place it in an ultrasonic reactor for ultrasonic reaction at 35°C for 40 minutes. After the reaction, use an ultra-high-speed machine to centrifuge at a speed of 11000 r / min for 30 minutes to separate the solid, and then wash it repeatedly with ultrapure water for 3 times. Finally, place it in a vacuum oven at 60°C and dry it to obtain the protonated black powder of oxadiazine polymer.

[0059] (2) Preparation of sensor:

[0060] Step 1: Use 10 ml of water, ethanol and acetone to ultrasonically clean the interdigital electrodes in order, and then dry them for later use;

[0061] Step 2: adding 4 mg of protonated cyanine polymer to 2 g of acetone by ultrasonication, and performing ultrasonic dispersion for 5 minutes to obtain a dispersion containing the protonated cyanine polymer;

[0062] Step 3: Apply the dispersion on the interdigital electrodes 8 times, and apply again after the surface is dry after each application. After application, place at room temperature, and after the solvent evaporates, place in an oven at 60°C for 1 hour to obtain a protonated polymer sensor with a film thickness of 300 μm.

[0063] (3) Determination of the response of protonated cyanine polymer to different humidity:

[0064] First, the device is placed in an atmosphere containing color-changing silica gel. After the current is stable, the device is placed in an atmosphere of saturated solutions of different metal salts. After the current is stable, the device is placed in an atmosphere of color-changing silica gel again. The above cycle is repeated. The results show that the protonated crotonyl cyanine polymer can achieve humidity detection in the range of 11% to 95% RH, and its response value to low humidity is greater than that of the polymer before protonation. The sensor also has good stability.

[0065] In summary, the invention includes but is not limited to the above embodiments. Any equivalent substitution or partial improvement made under the spirit and principle of the invention shall be deemed to be within the protection scope of the invention.

Claims

1. A protonated cyanine polymer, characterized in that: The structural formula of the polymer is: Where n is a positive integer, X is H or deuterium, A - Cl - 、HSO4 - 、H2PO4 - .

2. A method for preparing a protonated crotonyl cyanine polymer as claimed in claim 1, characterized in that: The method steps include: (1) Under a protective gas atmosphere, heating p-phenylenediamine and ketocyanine in a reaction solvent to react to obtain a crude product, and purifying the crude product to obtain a ketocyanine polymer powder; (2) mixing the crotonyl cyanine polymer powder and a proton source, heating and ultrasonically reacting the mixture, centrifuging the mixture after the reaction is complete, washing the solid, and vacuum drying the mixture to obtain a protonated crotonyl cyanine polymer; Wherein, the proton source is hydrochloric acid, sulfuric acid, phosphoric acid, deuterated hydrochloric acid, deuterated sulfuric acid or deuterated phosphoric acid.

3. A method for preparing a protonated crotonyl cyanine polymer as claimed in claim 1, characterized in that: In step (1), the molar ratio of p-phenylenediamine, crotonic acid and reaction solvent is 1:1:100-300.

4. A method for preparing a protonated crotonate cyanine polymer as claimed in claim 1, characterized in that: 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.

5. A method for preparing a protonated crotonate cyanine polymer as claimed in claim 1, characterized in that: In step (1), the reaction temperature is 90-130° C. and the reaction time is 9-16 h.

6. A method for preparing a protonated crotonyl cyanine polymer as claimed in claim 1, characterized in that: 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 crotonyl cyanine polymer powder.

7. A method for preparing a protonated crotonate cyanine polymer as claimed in claim 1, characterized in that: In step (2), the concentration of the proton source is 1 to 2 mol / L; The molar ratio of the crotonyl cyanine polymer to the proton source is 1:3-10.

8. A method for preparing a protonated crotonate cyanine polymer as claimed in claim 1, characterized in that: In step (2), the ultrasonic temperature is 20 to 60° C., and the ultrasonic time is 10 to 60 min; The centrifugal speed is 8000-13000 r / min, and the centrifugal time is 30-60 min; The vacuum drying temperature is 60-90°C.

9. A low humidity resistive sensor, characterized in that: The interdigitated electrodes of the sensor are coated with the protonated crotonate cyanine polymer of the present invention.

10. A low humidity resistive sensor as claimed in claim 9, characterized in that: The sensor is prepared by the following method, the method steps comprising: (1) ultrasonically dispersing the protonated crotonyl cyanine 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; (2) applying the dispersion onto the clean interdigital electrodes, removing the solvent by natural evaporation, and drying to obtain a low-humidity resistive sensor; Preferably, the solvent is one or more of ethanol, chloroform and acetone; Preferably, the brushing is completed with a brush pen, the brushing times are 5 to 10 times, and the surface is brushed again after each brushing. 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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