A protonated ketocyanine polymer, its preparation method, and a low-humidity resistive sensor

Abstract

This invention relates to a protonated ketone cyanine polymer, its preparation method, and a low-humidity resistive sensor, belonging to the field of organic semiconductor device technology. The polymer has the following structural formula: where n is a positive integer, X is hydrogen or deuterium, and A... ‑ For Cl ‑ HSO4 ‑ H2PO4 ‑ The polymer can form a more complete hydrogen bond network under low humidity, which increases its sensitivity under low humidity. While maintaining a response over a wide humidity range of 11% to 95%, it improves its sensitivity in the low humidity range (11% to 33% RH). In addition, the ions introduced by protonation can interact with the π-conjugated system through anion-π interactions, increasing the stability of the polymer.

Description

Technical Field

[0001] This invention relates to a protonated ketocyanine polymer, its preparation method, and a low-humidity resistive sensor, belonging to the field of organic semiconductor device technology. Background Technology

[0002] With the acceleration of industrialization and modernization, accurate monitoring of environmental humidity has become crucial for many fields. Humidity not only affects people's daily lives but also plays an important role in agriculture, industrial production, warehousing management, healthcare, building maintenance, and scientific research. Accurate detection in low-humidity environments is particularly important in these fields because low humidity conditions can significantly impact product quality, human health, and environmental stability. In low-humidity environments, traditional humidity sensors face problems such as long response times, low accuracy, and susceptibility to environmental interference. Furthermore, while these sensors typically perform well in high-humidity environments, their accuracy and stability are insufficient in low-humidity environments, such as deserts, dry laboratories, or specialized industrial environments. Therefore, developing a humidity detection technology that can operate stably and with high sensitivity in low-humidity environments is of great significance for improving work efficiency and safety in 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 physicochemical properties, such as good environmental adaptability, adjustable sensitivity, excellent mechanical properties, and cost-effectiveness. Organic polymer humidity sensors demonstrate great application potential due to 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, high-sensitivity, and economical resistive humidity sensors (Polymers, 2021, 13, 3019). However, existing organic polymers, such as ketone cyanine polymers, still suffer from low sensitivity and poor stability in humidity detection technology. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a protonated ketocyanine polymer, a preparation method thereof, 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 ketone cyanine polymer, the polymer having the following structural formula:

[0007] Where n is a positive integer, X is hydrogen or deuterium, and A - For Cl - HSO4 - H2PO4 - .

[0008] A method for preparing the protonated ketocyanine polymer of the present invention includes the following steps:

[0009] (1) Under a protective gas (nitrogen or inert gas) atmosphere, p-phenylenediamine and ketone acid are heated and reacted in a reaction solvent to obtain a crude product, which is then purified to obtain ketone acid cyanine polymer powder.

[0010] (2) Mix the ketocyanine polymer powder with a proton source, heat and sonicate the reaction. After the reaction is complete, centrifuge, wash the solid and vacuum dry to obtain a protonated ketocyanine polymer.

[0011] 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, ketone acid and reaction solvent is 1:1:100 to 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℃ and the reaction time is 9-16h.

[0015] Preferably, in step (1), during purification, the crude product is added to the extraction solvent, heated and stirred at 70-90°C for 24-48 hours under a protective gas atmosphere (nitrogen or inert gas), cooled naturally, filtered, and vacuum dried at 60-90°C to obtain ketocyanine 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 ketocyanine polymer and the proton source is 1:3 to 10.

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

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

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

[0021] A low-humidity resistive sensor, wherein the interdigitated electrodes of the sensor are coated with a protonated ketocyanine polymer as described in this invention.

[0022] Preferably, the sensor is prepared by the following method, the method steps of which include:

[0023] (1) The protonated ketocyanine polymer is ultrasonically dispersed in a solvent to obtain a dispersion; the mass ratio of the hydrogen-bonded heterojunction polymer to the solvent is 1:400-600; the ultrasonic time is 2-10 minutes.

[0024] (2) The dispersion is brushed onto a clean interdigitated 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, and more preferably chloroform.

[0026] Preferably, the coating is applied using a brush pen, with 5 to 10 brush strokes. After each brush stroke, the surface is allowed to dry before the next brush stroke is applied. The interdigitated electrode comprises an alumina substrate and a silver-palladium alloy electrode. The interdigitated width is 50 to 100 μm, the interdigitated spacing is 200 to 300 μm, the alumina 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 h.

[0027] Beneficial effects

[0028] This invention provides a protonated ketocyanine polymer that can form a more complete hydrogen bond network under low humidity, thereby increasing its sensitivity in low humidity conditions. While maintaining a response over a wide humidity range of 11%–95%, it improves its sensitivity in the low humidity range (11%–33% RH). When used in humidity sensors, this polymer exhibits significant advantages in sensitivity (up to five orders of magnitude variation) and detection humidity range (11–95% RH). Furthermore, the protonation-introduced ions can undergo anion-π interactions with the π-conjugated system, increasing the polymer's stability. Attached Figure Description

[0029] Figure 1 The infrared spectrum results are for the polymer described in Example 1.

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

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

[0032] Figure 4 The results are the stability test results of the sensor device described in Example 1. Detailed Implementation

[0033] The present invention will be further described in detail below with reference to specific embodiments.

[0034] Example 1

[0035] (1) Synthesis of protonated ketocyanine polymer

[0036] p-Phenylenediamine (0.56 g, 5 mmol), diethyl squaric acid (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-resistant flask. After loading a reflux apparatus, the air in the reaction system was purged four times with nitrogen. The temperature was then raised to 125 °C, the stirrer was turned on, and the reaction was refluxed for 12 h. After the reaction was complete, the temperature was allowed to drop to room temperature, the product was filtered, and dried in a vacuum oven at 70 °C to obtain a black powder crude product. The obtained crude product was then purified using a Soxhlet extractor, with tetrahydrofuran as the selected extractant. The crude product was loaded into a Soxhlet extractor, and the air in the reaction system was purged four times with nitrogen. The temperature was raised to 65 °C, the stirrer was turned on, and the reaction was refluxed for 36 h. After the temperature dropped to room temperature, the product was filtered, and dried in a vacuum oven at 65 °C to obtain 1.16 g of ketoxane cyanine polymer black powder.

[0037] Weigh out 1 mmol (214 mg) of ketone cyanine polymer black powder and 1 mol / L (5 mL) of proton source hydrochloric acid and place them in a single-necked pressure-resistant bottle equipped with a condenser. Then place the bottle in an ultrasonic reactor and sonicate at 25 °C for 30 min. After the reaction, centrifuge at 12000 r / min for 20 min using an ultra-high speed centrifuge to separate the solid. Wash the solid three times with ultrapure water and finally dry it in a vacuum oven at 70 °C to obtain protonated ketone cyanine polymer black powder.

[0038] The infrared spectral results of the polymer are as follows: Figure 1 As shown, the results indicate a shift in the absorption peak of the carbonyl group in the raw material keto acid and the product, confirming the occurrence of the polymer reaction. The solid-state NMR results of the polymer are shown below. Figure 2 As shown, the results indicate that the spectral results correspond one-to-one with the chemical environment of carbon in the structure.

[0039] (2) Sensor fabrication:

[0040] Step 1: Use 10ml of water, ethanol and acetone respectively to ultrasonically clean the interdigitated electrodes in sequence, and dry them for later use.

[0041] Step 2: Add 4 mg of protonated ketocyanine polymer to 2 g of chloroform by ultrasonication, and disperse by ultrasonication for 5 minutes to obtain a dispersion containing protonated ketocyanine polymer.

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

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

[0044] First, the sensor device was placed in an atmosphere containing color-changing silica gel. After the current stabilized, the device was placed in an atmosphere of saturated solutions of different metal salts. Similarly, after the current stabilized, the device was placed back in the atmosphere of color-changing silica gel. This cycle was repeated, and the results are as follows. Figure 3 As shown in the figure, the protonated ketone cyanine polymer can achieve humidity detection in the range of 11%–95% RH, and its response to low humidity is greater than that of the unprotonated polymer. The device stability test results are as follows... 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 ketocyanine polymer

[0047] Weigh p-phenylenediamine (1.08 g, 10 mmol), chlorhexidine (1.42 g, 10 mmol), toluene (92.2 g, 1 mol), and tetrahydrofuran (41 g, 1 mol) into a single-necked pressure-resistant flask. After loading a reflux apparatus, purge the air in the reaction system four times with nitrogen. Then, heat to 115 °C, turn on the stirrer, and reflux for 16 h. After the reaction is complete, allow the temperature to cool to room temperature, filter the product, and dry it in a vacuum oven at 80 °C to obtain a black powder crude product. The crude product is then purified using a Soxhlet extractor, with tetrahydrofuran as the selected extractant. After loading the crude product into a Soxhlet extractor, purge the air in the reaction system four times with nitrogen. Heat to 70 °C, turn on the stirrer, and reflux for 36 h. After cooling to room temperature, filter the product, and dry it in a vacuum oven at 70 °C to obtain 1.76 g of chlorhexidine cyanine polymer black powder.

[0048] Weigh out 2 mmol (428 mg) of ketocyanine polymer black powder and 1 mol / L (10 mL) of proton source phosphoric acid and place them in a single-necked pressure-resistant bottle equipped with a condenser. Then place the bottle in an ultrasonic reactor and sonicate at 35 °C for 20 min. After the reaction, centrifuge at 10,000 r / min for 30 min using an ultra-high speed centrifuge to separate the solid. Wash the solid three times with ultrapure water and finally dry it in a vacuum oven at 80 °C to obtain protonated ketocyanine polymer black powder.

[0049] (2) Sensor fabrication:

[0050] Step 1: Use 10ml of water, ethanol and acetone respectively to ultrasonically clean the interdigitated electrodes in sequence, and dry them for later use.

[0051] Step 2: Add 4 mg of protonated ketocyanine polymer to 2 g of ethanol by ultrasonication, and disperse by ultrasonication for 5 minutes to obtain a dispersion containing protonated ketocyanine polymer.

[0052] Step 3: Apply the dispersion to the interdigitated electrodes by brushing 8 times. After each application, allow the surface to dry before applying the next application. After brushing, place the electrode at room temperature until the solvent evaporates, then place it 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 ketocyanine polymer to different humidity levels:

[0054] First, the device was placed in an atmosphere containing color-changing silica gel. After the current stabilized, the device was placed in an atmosphere of saturated solutions of different metal salts. Again, after the current stabilized, the device was placed in the atmosphere of color-changing silica gel, and this cycle was repeated. The results showed that the protonated ketone cyanine polymer can achieve humidity detection in the range of 11%–95% RH, and its response value to low humidity is greater than that of the unprotonated polymer. Furthermore, the sensor exhibits good stability.

[0055] Example 3

[0056] (1) Synthesis of protonated ketocyanine polymer

[0057] p-Phenylenediamine (0.21 g, 2 mmol), chlorhexidine (0.28 g, 2 mmol), toluene (23.1 g, 0.25 mol), and tetrahydrofuran (10.3 g, 0.25 mol) were weighed and placed in a single-necked pressure-resistant flask. After loading a reflux apparatus, the air in the reaction system was replaced with nitrogen four times. The temperature was then raised to 130 °C, the stirrer was turned on, and the reaction was refluxed for 16 h. After the reaction was complete, the temperature was allowed to drop to room temperature, the product was filtered, and dried in a vacuum oven at 60 °C to obtain a black powder crude product. The crude product was then purified using a Soxhlet extractor, with tetrahydrofuran as the selected extractant. The crude product was placed in a Soxhlet extractor, and the air in the reaction system was replaced with nitrogen four times. The temperature was raised to 115 °C, the stirrer was turned on, and the reaction was refluxed for 36 h. After the temperature dropped to room temperature, the product was filtered, and dried in a vacuum oven at 60 °C to obtain 0.36 g of chlorhexidine cyanine polymer black powder.

[0058] Weigh out 1 mmol (214 mg) of ketone cyanine polymer black powder and 1 mol / L (8 mL) of proton source hydrochloric acid and place them in a single-necked pressure-resistant bottle equipped with a condenser. Then place the bottle in an ultrasonic reactor and sonicate at 35 °C for 40 min. After the reaction, centrifuge at 11000 r / min for 30 min using an ultra-high speed centrifuge to separate the solid. Wash the solid three times with ultrapure water and finally dry it in a vacuum oven at 60 °C to obtain protonated ketone cyanine polymer black powder.

[0059] (2) Sensor fabrication:

[0060] Step 1: Use 10ml of water, ethanol and acetone respectively to ultrasonically clean the interdigitated electrodes in sequence, and dry them for later use.

[0061] Step 2: Add 4 mg of protonated ketocyanine polymer to 2 g of acetone by ultrasonication and disperse by ultrasonication for 5 minutes to obtain a dispersion containing protonated ketocyanine polymer.

[0062] Step 3: Apply the dispersion to the interdigitated electrodes by brushing 8 times. After each application, allow the surface to dry before brushing again. After brushing, place the electrode at room temperature until the solvent evaporates, then place it 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 ketocyanine polymer to different humidity levels:

[0064] First, the device was placed in an atmosphere containing color-changing silica gel. After the current stabilized, the device was placed in an atmosphere of saturated solutions of different metal salts. Again, after the current stabilized, the device was placed in the atmosphere of color-changing silica gel, and this cycle was repeated. The results showed that the protonated ketone cyanine polymer can achieve humidity detection in the range of 11%–95% RH, and its response value to low humidity is greater than that of the unprotonated polymer. Furthermore, the sensor exhibits good stability.

[0065] In summary, the invention includes, but is not limited to, the above embodiments. Any equivalent substitutions or partial improvements made under the spirit and principles of this invention shall be considered to be within the protection scope of this invention.

Claims

1. A protonated ketocyanine polymer, characterized in that: The structural formula of the polymer is: Where n is a positive integer, X is H or deuterium, and A - For Cl - HSO4 - H2PO4 - ; The polymer is prepared by the following method, the steps of which include: (1) Under a protective gas atmosphere, p-phenylenediamine and ketone acid were heated and reacted in a reaction solvent to obtain a crude product, which was then purified to obtain ketone acid cyanine polymer powder. (2) Mix the ketocyanine polymer powder and the proton source, heat and sonicate the reaction. After the reaction is completed, centrifuge, wash the solid and vacuum dry to obtain a protonated ketocyanine polymer. The proton source is hydrochloric acid, sulfuric acid, phosphoric acid, deuterated hydrochloric acid, deuterated sulfuric acid, or deuterated phosphoric acid; In step (1), the molar ratio of p-phenylenediamine, ketone acid and reaction solvent is 1:1:100~300; the reaction solvent is a mixed solution of toluene and chloroform with a volume ratio of 1:1, or a mixed solution of toluene and acetonitrile with a volume ratio of 1:

1. In step (2), the concentration of the proton source is 1~2 mol / L; the molar ratio of the ketone cyanine polymer and the proton source is 1:3~10.

2. A method for preparing the protonated ketocyanine polymer according to claim 1, characterized in that: The method steps include: (1) Under a protective gas atmosphere, p-phenylenediamine and ketone acid were heated and reacted in a reaction solvent to obtain a crude product, which was then purified to obtain ketone acid cyanine polymer powder. (2) Mix the ketocyanine polymer powder and the proton source, heat and sonicate the reaction. After the reaction is completed, centrifuge, wash the solid and vacuum dry to obtain a protonated ketocyanine polymer. The proton source is hydrochloric acid, sulfuric acid, phosphoric acid, deuterated hydrochloric acid, deuterated sulfuric acid, or deuterated phosphoric acid; In step (1), the molar ratio of p-phenylenediamine, ketone acid and reaction solvent is 1:1:100~300; the reaction solvent is a mixed solution of toluene and chloroform with a volume ratio of 1:1, or a mixed solution of toluene and acetonitrile with a volume ratio of 1:

1. In step (2), the concentration of the proton source is 1~2 mol / L; the molar ratio of the ketone cyanine polymer and the proton source is 1:3~10.

3. The method for preparing a protonated ketocyanine polymer as described in claim 2, characterized in that: In step (1), the reaction temperature is 90~130℃ and the reaction time is 9~16h.

4. The method for preparing the protonated ketocyanine polymer as described in claim 2, characterized in that: In step (1), during purification, the crude product is added to the extraction solvent, heated and stirred at 70~90℃ for 24~48h under a protective gas atmosphere, cooled naturally, filtered, and vacuum dried at 60~90℃ to obtain ketocyanine polymer powder.

5. The method for preparing a protonated ketocyanine polymer as described in claim 2, characterized in that: In step (2), the ultrasonic temperature is 20~60℃ and the ultrasonic time is 10~60min; The centrifugation speed is 8000~13000 r / min, and the centrifugation time is 30~60 min; The vacuum drying temperature is 60~90℃.

6. A low humidity resistive sensor, characterized in that: The interdigitated electrodes of the sensor are coated with a protonated ketocyanine polymer as described in claim 1.

7. A low humidity resistive sensor as described in claim 6, characterized in that: The sensor is prepared by the following method, the steps of which include: (1) The protonated ketocyanine polymer is ultrasonically dispersed in a solvent to obtain a dispersion; the mass ratio of the hydrogen-bonded heterojunction polymer to the solvent is 1:400~600; the ultrasonic time is 2~10 minutes; (2) The dispersion is brushed onto a clean interdigitated electrode, and after the solvent is naturally evaporated and removed, it is dried to obtain a low humidity resistive sensor. The solvent is one or more of ethanol, chloroform, and acetone; The coating is applied using a brush pen, with 5-10 brush strokes. After each brush stroke, the surface is allowed to dry before the next brush stroke. The interdigitated electrode comprises an alumina substrate and a silver-palladium alloy electrode. The interdigitated width is 50-100 μm, the interdigitated spacing is 200-300 μm, the alumina substrate thickness is 1-2 mm, and the silver-palladium alloy electrode thickness is 100-200 nm. The drying temperature is 50-80℃, and the drying time is 0.5-2 h.

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