CN114672020B - Preparation method of benzoxazinyl conjugated trapezoid polymer and application of benzoxazinyl conjugated trapezoid polymer in hydrogen sulfide detection - Google Patents

Abstract

A preparation method of benzoxazine-based conjugated ladder polymer and its application in hydrogen sulfide detection. The benzoxazine-based conjugated ladder polymer uses diaminoquinone molecules as the A monomer and benzoquinone compounds as the B monomer and passes through a polymerization reaction kettle and a vacuum atmosphere furnace to generate polybenzoxazines. Ladder-shaped conductive polymers are then prepared to prepare gas sensing devices for detecting acidic gases such as hydrogen sulfide. The advantages of the invention are that the polymer is simple to prepare, has low cost, and has high specificity and sensitivity in detecting hydrogen sulfide. Moreover, the benzoxazine-based conjugated ladder polymer has significant semiconductor properties, can operate at room temperature, and has low power consumption requirements. It may be suitable for wearable sensors or rapid on-site detection of acute toxic and corrosive hydrogen sulfide gas, such as Pipelines and sewage treatment, it can also be used as the core material of portable hydrogen sulfide tester and has broad application prospects in the field of gas detection.

Description

A kind of preparation method of benzoxazine-based conjugated ladder polymer and its use in hydrogen sulfide detection Applications being tested

Technical field

The invention belongs to the technical field of polymer semiconductors, and particularly relates to a preparation method of a benzoxazine-based conjugated ladder polymer and its application in hydrogen sulfide detection.

Background technique

Hydrogen sulfide is a highly corrosive pollutant gas that is commonly found in natural gas streams and can also be produced by anaerobic bacteria decomposing organic matter. According to the National Institute of Occupational Safety and Health, the allowable human exposure limit for hydrogen sulfide is about 20 ppm. Exceeding 100 ppm is directly dangerous to life. Hydrogen sulfide has acute toxicity, which has promoted the development of low-cost and portable sensing technology. Technology can quickly identify trace concentrations of hydrogen sulfide in environments such as mines, natural gas pipelines and wastewater treatment plants. Therefore, detecting exogenous hydrogen sulfide has attracted considerable research interest, and research on hydrogen sulfide sensors is also developing rapidly. References can be found in: (1) Máté J.Bezdek, Luo S There are two main on-site hydrogen sulfide detection methods: one is to directly take samples and send them to the laboratory, and use gas chromatography for energy spectrum analysis to obtain the hydrogen sulfide concentration. This method is highly accurate, but it is a single-point test, sampling and The sample measurement workload is large, the cycle is long, and the cost is relatively high, making it difficult to reflect the instantaneous changes in hydrogen sulfide in a timely manner. The second is to install hydrogen sulfide online detection equipment to detect dynamic changes in hydrogen sulfide concentration in real time. This method is highly accurate, but expensive. , suitable for sour gas fields where hydrogen sulfide gas wells are concentrated and the hydrogen sulfide concentration is relatively high. Currently, portable hydrogen sulfide testers are used to detect low-concentration hydrogen sulfide at the wellhead or gas gathering station for open-air real-time multi-point detection. This method is easy to operate and low-cost. Most of the core materials of current portable hydrogen sulfide testers are inorganic materials. The preparation process of this material is relatively complex and requires high manufacturing equipment. However, polymer materials are simple to prepare and have low requirements for manufacturing equipment and low cost. Therefore, research on hydrogen sulfide-responsive polymers, the core material of portable hydrogen sulfide testers, emerged at the historic moment.

According to the search literature, in 2016 Gong Xiaohui of Southeast University synthesized a ladder-shaped polybenzoxazine-based polymer using 1,4-p-phenylenediamine and tetrachlorobenzoquinone. However, its main research was on its performance as a supercapacitor material and did not When it comes to hydrogen sulfide detection performance, the preparation method in this patent is different from Gong Xiaohui's preparation method, and the applications are different. References can be found in: (2) Gong . Design, synthesis and performance research of triphenyldioxazine-based optoelectronic materials [D]. Southeast University, 2016.

Contents of the invention

The purpose of the present invention is to provide a preparation method of benzoxazine-based conjugated ladder polymer and its application in hydrogen sulfide detection in view of the above technical analysis and existing problems.

The technical solution of the present invention is as follows:

A method for preparing a benzoxazine-based conjugated ladder polymer. The benzoxazine-based conjugated ladder polymer uses diaminoquinone molecules as monomer A and benzoquinone compounds as monomer B. The body is formed into a ring through polymerization reaction, and then heat-treated in a vacuum drying vacuum atmosphere furnace to form a benzoxazine-based conjugated ladder polymer. The structural formula of the polymer is as follows,

The R group is a chlorine atom, a bromine atom, an iodine atom or a hydrogen atom.

The A monomer is 3,6-diamino-2,5-benzenediol, 4,6-diamino-1,3-benzenediol, 1,2-diamino-3,6-benzenediol , 3,5-diamino-2,6-benzenediol, 3,5-diamino-2,6-pyridinediol, 1,5-diamino-4,8-naphthalenediol, 3,3- Dihydroxy-4,4-biphenyldiamine or 1,2-diamino-3,8-naphthodiol and its hydrochloride, their structural formulas are as follows:

The B monomer is 2,5-dihydroxybenzoquinone, 2,5-dihydroxy-6-chlorobenzoquinone, 2,5-dihydroxy-3,6-dichlorobenzoquinone, 2,5-dihydroxy -6-bromoquinone, 2,5-dihydroxy-3,6-dibromoquinone, 2,5-dihydroxy-6-iodoquinone or 2,5-dihydroxy-3,6-diiodobenzene Quinones, their structural formulas are as follows:

The specific steps of the preparation method of the benzoxazinyl conjugated ladder polymer are:

Add A monomer and B monomer into the polymerization reactor at a molar ratio of 1:1-1:1.2, add anhydrous high-boiling point solvent, stir evenly, add argon gas, heat the reaction, and then cool to room temperature. Then the first post-processing is performed to obtain polymer precursor powder. After drying, the polymer precursor powder is placed in a vacuum atmosphere furnace for heating treatment, and then the process is lowered to room temperature. Finally, a second post-processing is performed to obtain benzoxazine-based conjugated ladder polymer powder.

Among them, anhydrous high-boiling point solvents are anhydrous N,N-dimethylacetamide (DMAC), N-methylpyrrolidone (NMP), hexamethylphosphoramide (HMPA), 1,4-dioxane ( DO), diglyme (DGDE) or N,N-dimethylformamide (DMF), etc.;

The reaction temperature is 100-160°C, the time is 24-120h, and the argon flow rate is 30-100ml/min;

For the first and second post-processing, pour into a centrifuge tube, add ultrapure water, centrifuge, wash 6 times, and absolute ethanol, wash 3 times. Vacuum drying at 60℃ for 48h;

The polymer precursor powder is heated in a vacuum atmosphere furnace at a temperature of 280-350°C, a maintenance time of 2-5h, a heating rate of 5°C/min, and a program to lower to room temperature for 30min at 5-10°C.

The present invention also provides the application of benzoxazine-based conjugated ladder polymer in preparing benzoxazine-based conjugated ladder polymer gas sensor device for hydrogen sulfide detection.

the way is:

The benzoxazine-based conjugated ladder polymer powder is stirred in a low boiling point solvent and dispersed evenly by ultrasonic, and is evenly coated on the surface of the substrate with a micro-injector, and treated in a constant temperature and humidity chamber to obtain the benzoxazine-based co-conjugated polymer powder. Yoke trapezoidal polymer gas sensing device;

Place the installed gas sensor device in an atmosphere of hydrogen sulfide gas and test its hydrogen sulfide response value.

Wherein, the dosage of the benzoxazinyl conjugated ladder polymer powder is 10-100 mg, the preferred low boiling point solvent is dichloromethane, chloroform, ethyl acetate, methanol, ethanol, n-hexane or tetrahydrofuran, etc., the preferred base It is glass, ceramic, polyimide (PI), polyethylene terephthalate (PET) or interdigital electrode. The thickness of the organic semiconductor gas sensing device is preferably 50-500 microns, and the processing temperature of the constant temperature and humidity chamber is preferably The temperature is 40°C, the humidity is 15%, the time is 5 hours, and the preferred hydrogen sulfide gas concentration is 0-100ppm.

The advantages and beneficial effects of the present invention are:

Compared with the preparation method in reference (2), the preparation method of the ladder-shaped conductive polymer constructed based on A monomer and B monomer of the present invention is simple and has lower cost. The prepared conjugated polymer has good electrical conductivity and thermal stability. It shows high specificity, high sensitivity, high recovery responsiveness, good thermal stability and good chemical stability for hydrogen sulfide detection. Moreover, the benzoxazine-based conjugated ladder polymer has significant semiconductor properties, can operate at room temperature, and has low power consumption requirements. It may be suitable for wearable sensors or on-site rapid detection of acute toxic and corrosive hydrogen sulfide gas, such as Pipelines and sewage treatment, it can also be used as the core material of portable hydrogen sulfide tester and has broad application prospects in the field of hydrogen sulfide detection.

Description of the drawings

Figure 1 shows the chemical reaction formula of monomer A and monomer B to generate benzoxazine-based conjugated ladder polymer.

Figure 2 is the chemical structural formula of monomer diaminobenzene phenols.

Figure 3 shows the chemical structural formula of monomer B benzoquinone compounds.

Figure 4 is the infrared spectrum of benzoxazine-based conjugated ladder polymer.

Figure 5 shows the response values of benzoxazine-based conjugated ladder polymer gas sensing devices in different organic vapor atmospheres.

Figure 6 shows the response-recovery curve of the benzoxazine-based conjugated ladder polymer gas sensor device under different hydrogen sulfide concentrations.

Figure 7 shows the response value of the benzoxazine-based conjugated ladder polymer gas sensor device at 0-100ppm.

Detailed ways

Example 1:

(1) A method for preparing a benzoxazine-based conjugated ladder polymer, the steps are as follows:

Add 21.3 grams of A monomer DAR (213.06) and 24.9 grams of B monomer chloranic acid (208.98) into the polymerization reactor, add 500 ml anhydrous NMP, vacuum and ventilate several times, program the temperature to 140°C, and stir evenly. Pour in argon gas (flow rate 70ml/min). Reaction 120h. After the reaction is completed, the reaction kettle is cooled to room temperature, poured into a centrifuge tube, centrifuged with ultrapure water, washed 6 times, and washed 3 times with absolute ethanol. Vacuum dry at 60℃ for 48h. Take 10 grams of polymer powder and put it into a vacuum atmosphere furnace to program the temperature to 300°C and maintain it for 2 hours. Then the program dropped to room temperature (30min 10℃). Pour into a centrifuge tube, add ultrapure water, centrifuge, wash 6 times, and absolute ethanol, wash 3 times. After vacuum drying at 60°C for 48 hours, benzoxazine-based conjugated ladder polymer powder can be obtained. The polymer powder was tested with Bruker's VECTORN22 Fourier transform infrared spectrometer and a curve was drawn to obtain Figure 4.

(2) The application of benzoxazine-based conjugated ladder polymers in the preparation of benzoxazine-based conjugated ladder polymer gas sensing devices for hydrogen sulfide detection. The method is:

Take 10 mg of polymer powder, stir it in methylene chloride solvent and disperse it evenly by ultrasonic, use a micro-injector to evenly coat the surface of the interdigital electrode base, and place it in a constant temperature (40°C) and constant humidity (15%) box for 5 hours to form an organic semiconductor. Gas sensing device, device thickness is 50 microns. Place the installed gas sensor device in a hydrogen sulfide gas atmosphere (0-100ppm), test its hydrogen sulfide response value (R _air /R _response -1) and draw a curve to obtain Figure 7. Common organic vapor selections Figure 5 is the response value and the curve is drawn, and Figure 6 is the response-recovery curve value and the curve is drawn under the hydrogen sulfide atmosphere of 0-100ppm.

Example 2:

(1) A method for preparing a benzoxazine-based conjugated ladder polymer, the steps are as follows:

Add 21.3 grams of A monomer DAR (213.06) and 20.8 grams of B monomer chloranic acid (208.98) into the polymerization reaction kettle, add 450 ml anhydrous DMF, vacuum and ventilate several times, program the temperature to 100°C, and stir evenly. Pour in argon gas (flow rate 30ml/min). Reaction 24h. After the reaction is completed, the reaction kettle is cooled to room temperature, poured into a centrifuge tube, centrifuged with ultrapure water, washed 6 times, and washed 3 times with absolute ethanol. Vacuum dry at 60℃ for 48h. Then the program dropped to room temperature (30min5°C). Pour into a centrifuge tube, add ultrapure water, centrifuge, wash 6 times, and absolute ethanol, wash 3 times. Vacuum dry at 60℃ for 48h. The benzoxazine-based conjugated ladder polymer powder can be obtained.

(2) The application of benzoxazine-based conjugated ladder polymers in the preparation of benzoxazine-based conjugated ladder polymer gas sensing devices for hydrogen sulfide detection. The method is:

Take 100mg of polymer powder, stir it in methylene chloride solvent and disperse it evenly by ultrasonic, use a micro-injector to evenly coat the surface of the interdigital electrode base, and place it in a constant temperature (40°C) and constant humidity (15%) box for 5 hours to form an organic semiconductor. Gas sensing device, device thickness is 500 microns. Place the installed gas sensor device in a hydrogen sulfide gas atmosphere (0-100ppm) and test its hydrogen sulfide response value (R _air /R _response -1).

Example 3:

(1) A method for preparing a benzoxazine-based conjugated ladder polymer, the steps are as follows:

Add 14 grams of A monomer 4,6 diaminoresorcin (140.138) and 15.4 grams of B monomer 2,5-dihydroxybenzoquinone (140.09) into the polymerization reaction kettle, add 480 ml anhydrous NMP, and vacuum for more After the first ventilation, program the temperature to 160°C, stir evenly, and introduce argon gas (flow rate 100 ml/min). Reaction 48h. After the reaction is completed, the reaction kettle is cooled to room temperature, poured into a centrifuge tube, centrifuged with ultrapure water, washed 6 times, and washed 3 times with absolute ethanol. Vacuum dry at 60℃ for 48h. Put 5 grams of polymer powder into a vacuum atmosphere furnace and program the temperature to 350°C for 3 hours. Then the program dropped to room temperature (30min5°C). Pour into a centrifuge tube, add ultrapure water, centrifuge, wash 6 times, and absolute ethanol, wash 3 times. Vacuum dry at 60℃ for 48h. The benzoxazine-based conjugated ladder polymer powder can be obtained.

(2) The application of benzoxazine-based conjugated ladder polymers in the preparation of benzoxazine-based conjugated ladder polymer gas sensing devices for hydrogen sulfide detection. The method is:

Take 50 mg of polymer powder, stir it in methylene chloride solvent and disperse it evenly by ultrasonic, use a micro-injector to evenly coat the surface of the glass substrate, and place it in a constant temperature (40°C) and constant humidity (15%) box for 5 hours to become an organic semiconductor gas sensor. The thickness of the device is 200 microns. Place the installed gas sensor device in a hydrogen sulfide gas atmosphere (0-100ppm) and test its hydrogen sulfide response value (R _air /R _response -1).

Example 4:

(1) A method for preparing a benzoxazine-based conjugated ladder polymer, the steps are as follows:

Add 14 grams of A monomer 4,6 diaminoresorcin (140.138) and 14 grams of B monomer 2,5-dihydroxybenzoquinone (140.09) into the polymerization reaction kettle, add 450 ml anhydrous NMP, and vacuum for more After the first ventilation, program the temperature to 160°C, stir evenly, and introduce argon gas (flow rate 80 ml/min). Reaction 48h. After the reaction is completed, the reaction kettle is cooled to room temperature, poured into a centrifuge tube, centrifuged with ultrapure water, washed 6 times, and washed 3 times with absolute ethanol. Vacuum dry at 60℃ for 48h. Put 5 grams of polymer powder into a vacuum atmosphere furnace and program the temperature to 350°C for 3 hours. Then the program dropped to room temperature (30min5°C). Pour into a centrifuge tube, add ultrapure water, centrifuge, wash 6 times, and absolute ethanol, wash 3 times. Vacuum dry at 60℃ for 48h. The benzoxazine-based conjugated ladder polymer powder can be obtained.

(2) The application of benzoxazine-based conjugated ladder polymers in the preparation of benzoxazine-based conjugated ladder polymer gas sensing devices for hydrogen sulfide detection. The method is:

Take 50 mg of polymer powder, stir it in an ethanol solvent and disperse it evenly by ultrasonic, then apply it evenly on the surface of the glass substrate with a micro-injector, and place it in a constant temperature (40°C) and constant humidity (15%) box for 5 hours to become an organic semiconductor gas sensing device. Device thickness is 400 microns. Place the installed gas sensor device in a hydrogen sulfide gas atmosphere (0-100ppm) and test its hydrogen sulfide response value (R _air /R _response -1).

Example 5:

(1) A method for preparing a benzoxazine-based conjugated ladder polymer, the steps are as follows:

Add 14 grams of A monomer 3,6-diamino-2,5-benzenediol (140.138) and 18.4 grams of B monomer 2,5-dihydroxy 6-chlorobenzoquinone (175.53) into the polymerization reaction kettle. 500ml of anhydrous DMAC, vacuumed and ventilated several times, programmed to raise the temperature to 120°C, stir evenly, and add argon gas (flow rate 50ml/min). Reaction 64h. After the reaction is completed, the reaction kettle is cooled to room temperature, poured into a centrifuge tube, centrifuged with ultrapure water, washed 6 times, and washed 3 times with absolute ethanol. Vacuum dry at 60℃ for 48h. Put 6 grams of polymer powder into a vacuum atmosphere furnace and program the temperature to 320°C for 4 hours. Then the program dropped to room temperature (30min 6°C). Pour into a centrifuge tube, add ultrapure water, centrifuge, wash 6 times, and absolute ethanol, wash 3 times. Vacuum dry at 60℃ for 48h. The benzoxazine-based conjugated ladder polymer powder can be obtained.

(2) The application of benzoxazine-based conjugated ladder polymers in the preparation of benzoxazine-based conjugated ladder polymer gas sensing devices for hydrogen sulfide detection. The method is:

Take 100 mg of polymer powder and stir it in ethanol solvent and disperse it evenly by ultrasonic. Use a micro-injector to evenly apply it on the surface of the glass substrate. Put it in a constant temperature (40°C) and constant humidity (15%) box for 5 hours to become an organic semiconductor gas sensing device. Device thickness is 100 microns. Place the installed gas sensor device in a hydrogen sulfide gas atmosphere (0-100ppm) and test its hydrogen sulfide response value (R _air /R _response -1).

Example 6:

(1) A method for preparing a benzoxazine-based conjugated ladder polymer, the steps are as follows:

Add 14 grams of A monomer 3,6-diamino-2,5-benzenediol (140.138) and 15.1 grams of B monomer 2,5-dihydroxybenzoquinone (140.09) into the polymerization reaction kettle, and add 500 ml anhydrous DMAC, after vacuuming and ventilating several times, program the temperature to 140°C, stir evenly, and introduce argon gas (flow rate 50ml/min). Reaction 64h. After the reaction is completed, the reaction kettle is cooled to room temperature, poured into a centrifuge tube, centrifuged with ultrapure water, washed 6 times, and washed 3 times with absolute ethanol. Vacuum dry at 60℃ for 48h. Put 6 grams of polymer powder into a vacuum atmosphere furnace and program the temperature to 320°C for 4 hours. Then the program dropped to room temperature (30min 8°C). Pour into a centrifuge tube, add ultrapure water, centrifuge, wash 6 times, and absolute ethanol, wash 3 times. Vacuum dry at 60°C for 48 hours. The benzoxazine-based conjugated ladder polymer powder can be obtained.

(2) The application of benzoxazine-based conjugated ladder polymers in the preparation of benzoxazine-based conjugated ladder polymer gas sensing devices for hydrogen sulfide detection. The method is:

Take 80 mg of polymer powder and stir it in ethanol solvent and disperse it evenly by ultrasonic. Use a micro-injector to evenly coat the surface of the PI substrate. Place it in a constant temperature (40°C) and constant humidity (15%) box for 5 hours to become an organic semiconductor gas sensing device. Device thickness is 180 microns. Place the installed gas sensor device in a hydrogen sulfide gas atmosphere (0-100ppm) and test its hydrogen sulfide response value (R _air /R _response -1).

Example 7:

(1) A method for preparing a benzoxazine-based conjugated ladder polymer, the steps are as follows:

Add 14 grams of A monomer 3,6-diamino-2,5-benzoquinone (140.138) and 20.8 grams of B monomer 2,5-dihydroxy-3,6-dichlorobenzoquinone (208.98) into the polymerization reaction In the kettle, add 480 ml of anhydrous NMP, evacuate and ventilate several times, program the temperature to 140°C, stir evenly, and introduce argon gas (flow rate 50 ml/min). Reaction 64h. After the reaction is completed, the reaction kettle is cooled to room temperature, poured into a centrifuge tube, centrifuged with ultrapure water, washed 6 times, and washed 3 times with absolute ethanol. Vacuum dry at 60℃ for 48h. Put 6 grams of polymer powder into a vacuum atmosphere furnace and program the temperature to 320°C for 4 hours. Then the program dropped to room temperature (30min 8℃). Pour into a centrifuge tube, add ultrapure water, centrifuge, wash 6 times, and absolute ethanol, wash 3 times. Vacuum dry at 60℃ for 48h. The benzoxazine-based conjugated ladder polymer powder can be obtained.

(2) The application of benzoxazine-based conjugated ladder polymers in the preparation of benzoxazine-based conjugated ladder polymer gas sensing devices for hydrogen sulfide detection. The method is:

Take 80mg of polymer powder, stir it in ethyl acetate solvent and disperse it evenly by ultrasonic, use a micro-injector to evenly coat the surface of the PI substrate, and place it in a constant temperature (40°C) and constant humidity (15%) box for 5 hours to become an organic semiconductor gas sensor. The device thickness is 150 microns. Place the installed gas sensor device in a hydrogen sulfide gas atmosphere (0-100ppm) and test its hydrogen sulfide response value (R _air /R _response -1).

Example 8:

(1) A method for preparing a benzoxazine-based conjugated ladder polymer, the steps are as follows:

Add 14 grams of A monomer 1,2-diamino-3,6-benzenediol (140.138) and 24.9 grams of B monomer 2,5-dihydroxy-3,6-dichlorobenzoquinone (208.98) into the polymerization reaction In the kettle, add 450 ml of anhydrous DMF, evacuate and ventilate several times, program the temperature to 100°C, stir evenly, and introduce argon gas (flow rate 50 ml/min). Reaction 120h. After the reaction is completed, the reaction kettle is cooled to room temperature, poured into a centrifuge tube, centrifuged with ultrapure water, washed 6 times, and washed 3 times with absolute ethanol. Vacuum dry at 60℃ for 48h. Put 10 grams of polymer powder into a vacuum atmosphere furnace and program the temperature to 300°C for 4 hours. Then the program dropped to room temperature (30min 8°C). Pour into a centrifuge tube, add ultrapure water, centrifuge, wash 6 times, and absolute ethanol, wash 3 times. Vacuum dry at 60℃ for 48h. The benzoxazine-based conjugated ladder polymer powder can be obtained.

(2) The application of benzoxazine-based conjugated ladder polymers in the preparation of benzoxazine-based conjugated ladder polymer gas sensing devices for hydrogen sulfide detection. The method is:

Take 60 mg of polymer powder, stir it in ethyl acetate solvent and disperse it evenly by ultrasonic, use a micro-injector to evenly coat the surface of the PET substrate, and place it in a constant temperature (40°C) and constant humidity (15%) box for 5 hours to become an organic semiconductor gas sensor. The thickness of the device is 80 microns. Place the installed gas sensor device in a hydrogen sulfide gas atmosphere (0-100ppm) and test its hydrogen sulfide response value (R _air /R _response -1).

Claims (4)

1. The application of a benzoxazine-based conjugated ladder polymer in the preparation of a benzoxazine-based conjugated ladder polymer gas sensor device for hydrogen sulfide detection, characterized in that the method is: The benzoxazine-based conjugated ladder polymer powder is stirred in a low boiling point solvent and dispersed evenly by ultrasonic, and is evenly coated on the surface of the substrate with a micro-injector, and treated in a constant temperature and humidity chamber to obtain the benzoxazine-based co-conjugated polymer powder. Yoke trapezoidal polymer gas sensing device; Place the installed gas sensor device in an atmosphere of hydrogen sulfide gas and test its hydrogen sulfide response value; The preparation method of the benzoxazine-based conjugated ladder polymer is to use diaminoquinone molecules as monomer A and benzoquinone compounds as monomer B through polymerization in a polymerization reactor, Then vacuum drying is performed, and finally the ring is formed by heat treatment in a vacuum atmosphere furnace to generate a benzoxazine-based conjugated ladder polymer. The structural formula of the polymer is as follows The R group is a chlorine atom, a bromine atom, an iodine atom or a hydrogen atom; The specific steps of the preparation method are as follows: Add A monomer and B monomer with a molar ratio of 1:1-1:1.2 into the polymerization reactor, add anhydrous high-boiling point solvent, stir evenly, add argon gas, and react at a reaction temperature of 100-160°C 24-120h, cool to room temperature, and then perform the first post-processing to obtain polymer precursor powder. After drying, put the polymer precursor powder into a vacuum atmosphere furnace and maintain it at 280-350°C for 2-5h, with a heating rate of 5 ℃/min, the post-processing program is lowered to room temperature, and finally the second post-processing is performed to obtain benzoxazine-based conjugated ladder polymer powder; The structural formula of monomer A, 3,6-diamino-2,5-benzenediol, is as follows: The B monomer includes 2,5-dihydroxybenzoquinone, 2,5-dihydroxy-6-chlorobenzoquinone, 2,5-dihydroxy-3,6-dichlorobenzoquinone, 2,5-dihydroxybenzoquinone, Hydroxy-6-bromoquinone, 2,5-dihydroxy-3,6-dibromoquinone, 2,5-dihydroxy-6-iodoquinone or 2,5-dihydroxy-3,6-diiodo Benzoquinone, its structural formula is as follows: 2. Application according to claim 1, characterized in that, Anhydrous high boiling point solvents are anhydrous N,N-dimethylacetamide (DMAC), N-methylpyrrolidone (NMP), hexamethylphosphoramide (HMPA), and 1,4-dioxane (DO) , diglyme (DGDE) or N,N-dimethylformamide (DMF); The argon gas flow rate is 30-100ml/min, and the program is lowered to room temperature for 30min5-10℃; The first and second post-processing were poured into a centrifuge tube, centrifuged with ultrapure water, washed 6 times with absolute ethanol, washed 3 times, and vacuum dried at 60°C for 48 hours. 3. The application according to claim 1, characterized in that the dosage of the benzoxazine-based conjugated ladder polymer powder is 10-100 mg; The substrate is glass, ceramic, polyimide (PI), polyethylene terephthalate (PET) or interdigitated electrode; The thickness of the benzoxazine-based conjugated ladder polymer gas sensor device is 50-500 microns; The temperature in the constant temperature and humidity box is 40°C, the humidity is 15%, and the time is 5 hours; The concentration of hydrogen sulfide gas is 0-100ppm. 4. Application according to claim 1, characterized in that the low boiling point solvent is dichloromethane, chloroform, ethyl acetate, methanol, ethanol, n-hexane or tetrahydrofuran.