An organic alternating copolymer, a sensor based on the copolymer, and its preparation and application

Abstract

The present invention relates to an organic alternating copolymer, a sensor based on the copolymer, and its preparation and application. The organic alternating copolymer is dissolved and mixed with carbon nanotubes, and the mixture is then applied to an electrode surface to produce a sensor device. The sensor device specifically interacts with nitrogen dioxide gas (NO2), causing a change in the device's resistance. Based on this change in resistance signal, NO2 gas can be specifically identified. Furthermore, based on the rate of resistance change, quantitative detection of NO2 concentration can be achieved.

Description

Technical Field

[0001] The present invention belongs to the field of functional polymers, and in particular relates to an organic alternating copolymer, a sensor based on the copolymer, and preparation and application thereof. Background Art

[0002] Nitrogen dioxide (NO2) is one of the main pollutants involved in air quality index (AQI) assessments, primarily originating from vehicle exhaust and industrial emissions. NO2 emissions not only cause serious environmental pollution problems, such as acid rain, PM2.5, and photochemical smog, but also severely impact human health. Long-term inhalation of NO2 can damage the nervous and cardiovascular systems. Therefore, highly sensitive detection of low-concentration NO2 gas is crucial for both environmental protection and human health. Currently, common NO2 gas detection methods include spectrophotometry, ion chromatography, chemiluminescence, and differential absorption spectroscopy. However, these methods are often expensive and complex in practice. Carbon nanotube (CNT)-based sensors have become a research hotspot due to their unique nanostructure and excellent physicochemical properties. However, the development of pure CNT-based sensors has been significantly limited by their poor selectivity and low sensitivity.

[0003] CN115520855A describes a method for preparing a nitrogen dioxide gas sensor based on nitrogen doping to modify single-walled carbon nanotubes. The detection limit is only 1 ppm, and it does not have excellent selectivity and the overall sensing effect is average.

[0004] Wang X (Wang X, Miaomiao W, Li X, et al. Large-Area Flexible Printed Thin-Film Transistors with Semiconducting Single-Walled Carbon Nanotubes for NO2Sensors [J]. ACS Applied Materials & Interfaces, 2020. DOI: 10.1021 / acsami.0c13824.) et al. used single-walled carbon nanotubes to construct a field-effect transistor sensor, with a detection limit of only 500 ppb and poor sensitivity.

[0005] Chae H (Chae H, Han JM, Ahn Y, et al. NO2-Affinitive Amorphous Conjugated Polymer for Field-Effect Transistor Sensor toward Improved NO2 Detection Capability [J]. Advanced Materials Technologies [2024-03-25]. DOI: 10.1002 / admt.202100580.) reported the detection of nitrogen dioxide molecules by a field-effect transistor sensor prepared based on organic polymers. Although the detection limit can reach 100 ppb, there is a problem that the sensing curve cannot be fully recovered, and the obvious baseline drift limits its feasibility in practical application. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an organic alternating copolymer, a sensor based on the copolymer, and its preparation and application, in particular to an alternating copolymer in which fluorene or carbazole is connected to benzene by a single bond, its sensing material, sensor, and its preparation and application.

[0007] The present invention provides a copolymer of alkoxybenzenes substituted with Ar1 and Ar2, wherein Ar1 is a fluorene substituted with one or more alkyl bromides at the 9,9 side chain, or a carbazole unit substituted with a alkyl bromide at the N side chain, and Ar2 is a triazole unit.

[0008] The present invention provides a polymer represented by the following general formula I:

[0009]

[0010] Where Ar1 is At least one of;

[0011] Said Ar2 is At least one of;

[0012] Wherein R1 is a bromoalkyl group;

[0013] k is the number of repeating units of the polymer, and is a natural number between 1 and 1000.

[0014] Preferably, the R1 is C n H 2n+1-m Brm, n is a positive integer from 1 to 20, and m is a positive integer from 1 to 3;

[0015] Preferably, R2 is selected from a hydrogen atom, an alkyl group, a substituted alkyl group, an ester group, an acyl group, an alkoxy group or a cyano group; wherein the substituent in the substituted alkyl group includes at least one of a hydroxyl group and an amino group.

[0016] More preferably, the R2 is C 12 H 25 .

[0017] Preferably, the polymer is

[0018]

[0019] Furthermore, the polymer is

[0020] Where n is a natural number between 1 and 1000.

[0021] The present invention provides a method for preparing the polymer, comprising:

[0022] A fluorene monomer having a bromoalkyl group substituted in the 9,9-position side chain and substituted with a diboron ester in the 2,7-position or a carbazole monomer having a bromoalkyl group substituted in the N-position side chain and substituted with a triazole functional group in the 1,4-position side chain and substituted with a bromo benzene ring monomer in the 2,5-position is subjected to a Suzuki coupling reaction to obtain a polymer.

[0023] The preparation method comprises:

[0024] (1) reacting 2,7-dibromofluorene or carbazole with a long-chain bromohydrocarbon monomer to obtain a fluorene or carbazole monomer compound with R1 as a side chain, and then reacting with bis-pinacol diboron to obtain a monomer compound with boron esters at both ends;

[0025] (2) reacting 2,5-dibromo-1,4-benzenediol with 3-bromo-1-trimethylsilyl-1-propyne to obtain a monomer compound with bromine at both ends, then performing a deprotection reaction to obtain a monomer compound with an alkynyl terminal, and then performing a click reaction on the monomer compound with an alkynyl terminal and a monomer with an azide group to obtain a monomer with bromine at both ends and a triazole functional group on the side chain;

[0026] (3) A monomer compound having boron ester at both ends is polymerized with a monomer having bromine at both ends and a triazole functional group on the side chain to obtain a polymer.

[0027] Further,

[0028] (1) reacting 2,7-dibromofluorene or carbazole with a long-chain bromohydrocarbon monomer to obtain a fluorene or carbazole monomer compound 3 in which R1 is a side chain, and then reacting this monomer with bis-pinacol diboron to obtain a monomer compound 5 in which both ends are boronic esters;

[0029] (2) reacting 2,5-dibromo-1,4-benzenediol with 3-bromo-1-trimethylsilyl-1-propyne to obtain a monomer compound 8 with bromine at both ends, then deprotecting the monomer to obtain a monomer compound 9 with an alkynyl terminal, and then reacting the monomer with an azide group-containing monomer 10 through a click reaction to obtain a monomer 11 with bromine at both ends and a triazole functional group on the side chain;

[0030] (3) The monomer compound 5 and the monomer compound 11 are polymerized to obtain the organic polymer 12.

[0031] The following formula takes the reaction of 2,7-dibromofluorene monomer as an example:

[0032]

[0033] The present invention provides a sensing material, characterized in that the sensing material comprises any one of the polymer sensing probes and carbon nanotubes.

[0034] Preferably, the carbon nanotubes are one or more of single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes, hydroxylated carbon nanotubes, carboxylated carbon nanotubes, amidated carbon nanotubes, and graphitized carbon nanotubes;

[0035] Preferably, the mass ratio of the polymer sensing probe to the carbon nanotube is 1:1 to 1:10.

[0036] The present invention provides a sensor device, which comprises an electrode with the sensing material provided on the surface.

[0037] The present invention provides a method for preparing a sensor device, which comprises: attaching a polymer sensing probe to a carbon nanomaterial through non-covalent action, coating the probe on an electrode surface, and drying the resulting mixture to obtain a sensor.

[0038] The preparation method specifically includes: subjecting an organic solvent, carbon nanotubes, and a polymer to tip ultrasound to obtain a uniform mixed liquid, coating the mixed liquid on the electrode surface, and waiting for the solvent to evaporate to obtain a sensor device.

[0039] Preferably, the organic solvent is selected from one or more of N,N-dimethylformamide, dimethyl sulfoxide, chloroform, tetrahydrofuran, carbon tetrachloride, acetonitrile, toluene, and chlorobenzene.

[0040] Preferably, the electrodes include but are not limited to interdigital electrodes and fractal electrodes.

[0041] The electrodes can be prepared in batches using micro-nano processing technology, screen printing technology, etc.

[0042] The present invention provides an application of the sensing material or the sensing device in identifying, detecting or monitoring nitrogen dioxide (NO2) gas. When the sensing device is placed in an atmosphere containing nitrogen dioxide gas, the resistance of the sensor changes, thereby enabling the detection of NO2 gas.

[0043] Preferably, the lower limit of detection is 100 ppb.

[0044] The present invention provides an alternating copolymer of fluorene or carbazole and benzene connected by a single bond, wherein one or more bromine-substituted alkyl chains are introduced into the carbon-9 position of the fluorene or the N-terminus of the carbazole unit; and the 2 and 5 positions of the copolymerized benzene unit contain side chain substituents of triazole units. In the general structural formula of the organic polymer, R1 is CnH 2n+1-m Brm, n is a positive integer from 1 to 20, m is a positive integer from 1 to 3; R2: selected from hydrogen atom, alkyl group, substituted alkyl group, ester group, acyl group, alkoxy group or cyano group; wherein the substituent in the substituted alkyl group includes at least one of hydroxyl group and amine group; k is the number of repeating units of the polymer. The alternating copolymer is obtained by copolymerizing a diboron ester containing a fluorene monomer and a dibrominated product containing a benzene monomer through a Suzuki coupling reaction. It is further dissolved and mixed with carbon nanotubes, and the mixture is then applied to the electrode surface to prepare a sensor device. The sensor device can specifically interact with nitrogen dioxide gas (NO2), causing the resistance of the device to change. Based on the change in the resistance signal, NO2 gas can be specifically identified; and based on the different resistance change rates, its quantitative detection application of NO2 concentration can be realized.

[0045] The gas sensing technology involved in this invention effectively functionalizes the side chains of organic polymers by introducing bromine atoms and triazole functional groups. This synergistic mechanism enables the efficient capture of nitrogen dioxide molecules. Furthermore, the organic polymer sensing probe is non-covalently bonded to carbon nanotubes, enabling the probe's adsorption of nitrogen dioxide to be reflected in changes in the electrical signal. Sensors using this sensor material can effectively achieve highly sensitive and specific sensing of nitrogen dioxide, achieving the goal of detecting low-concentration nitrogen dioxide molecules, which is of great significance for environmental protection and personal safety.

[0046] Beneficial effects

[0047] The gas-sensitive sensing technology involved in the present invention attaches organic polymer sensor probes and carbon nanotubes through non-covalent interactions, which improves the sensitivity while also enhancing the selectivity of the sensor material. It can monitor nitrogen dioxide gas in a timely manner, which is of great significance for environmental protection and personal safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 is the general structural formula of the polymer probe molecule in the present invention;

[0049] Figure 2 This is the general synthesis process of the polymer probe molecules in the present invention;

[0050] Figure 3 is the chemical structural formula of a representative probe molecule polymer selected in Example 1 of the present invention; wherein n=3.

[0051] Figure 4 This is a representative synthesis process of a probe molecule polymer selected from Example 1 of the present invention;

[0052] Figure 5 This is a scanning electron microscope image of the hydroxylated short-walled carbon nanotubes in Example 2 of the present invention;

[0053] Figure 6 This is a scanning electron microscope image of the sensor probe attached to the hydroxylated short-walled carbon nanotubes in Example 2 of the present invention;

[0054] Figure 7 Schematic diagram of the structure of the test electrode in the present invention;

[0055] Figure 8 The resistance change curve of the sensing material in Example 3 of the present invention to different concentrations of nitrogen dioxide gas;

[0056] Figure 9 This is a graph showing the response values ​​of the sensing material in Example 4 of the present invention to common interfering gases.

[0057] Figure 10 This is a hydrogen nuclear magnetic resonance spectrum of a representative probe molecule polymer selected and obtained in Example 1 of the present invention.

[0058] Figure 11 This is a gel permeation chromatogram of a representative probe molecule polymer selected in Example 1 of the present invention. DETAILED DESCRIPTION

[0059] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0060] Example 1

[0061] This embodiment provides a polymer-based sensor material. In this embodiment, 2,7-dibromofluorene and 2,5-dibromohydroquinone are used as raw materials, and multiple monomers with different side chains are synthesized separately and then copolymerized to obtain a polymer sensing probe.

[0062] like Figure 4 As shown, the following is the specific reaction process.

[0063] To a reaction flask, 2,7-dibromofluorene (1.62 g, 5 mmol), 1,6-dibromohexane (3.05 g, 12.5 mmol), 40 ml of 40% potassium hydroxide solution, 40 ml of toluene, and tetrabutylammonium bromide (0.32 g, 1 mmol) were added in sequence. The mixture was heated to 85°C and allowed to react for 12 hours. Then, 100 ml of water was added and the mixture was extracted twice with dichloromethane (2 x 100 ml). The organic phase was dried over anhydrous magnesium sulfate, spin-dried, and filtered to obtain 1.3 g of a white solid in a 40% yield.

[0064] Under argon, a reaction flask was charged with 2,7-dibromo-9,9-bis(6-bromohexyl) (1.95 g, 3 mmol), bispinacol diboron (2.29 g, 9 mmol), 0.9 g potassium acetate (0.98 g, 0.1 mmol), [1,1'-bis(diphenylphosphino)ferrocene]dichloropalladium dichloromethane complex (0.89 g, 9 mmol), and 60 ml of 1,4-dioxane. The mixture was heated to 80°C and reacted for 48 hours. The mixture was then poured into 100 ml of water and extracted twice with dichloromethane (2 x 150 ml). The organic phase was dried over anhydrous magnesium sulfate, spin-dried, and filtered to obtain 1.66 g of a white solid with a yield of 70%.

[0065] To a reaction flask, add 2,5-dibromohydroquinone (3.51 g, 13.1 mmol), 3-trimethylsilylpropynyl bromide (9.0 g, 32.7 mmol), potassium carbonate (18.1 g, 131 mmol), and 150 ml of acetone. Heat to 60°C and reflux for 24 hours. Extract with 100 ml of dichloromethane and 1 mol / L dilute hydrochloric acid (2 x 100 ml). The organic phase is dried over anhydrous magnesium sulfate, spin-dried, and filtered to obtain 4.2 g of a white solid (70% yield).

[0066] To a reaction flask at room temperature was added (((2,5-dibromo-1,4-phenylene)bis(oxy))bis(prop-1-yn-3,1-diyl))bis(trimethylsilane) (1.95 g, 4 mmol), 50 ml of tetrahydrofuran, and 50 ml of methanol. Potassium carbonate (2.27 g, 16 mmol) was added in small portions. The mixture was stirred for 2 hours, and 100 ml of water was added. The mixture was extracted twice with dichloromethane (2 x 100 ml). The organic phase was dried over anhydrous magnesium sulfate, spin-dried, and filtered to afford 0.97 g of a white solid in a 71% yield.

[0067] Under argon, a reaction flask was charged with 1,4-dibromo-2,5-bis(prop-2-yn-1-yloxy)benzene (0.35 g, 1 mmol), 1-azidododecane (0.84 g, 4 mmol), anhydrous copper sulfate (0.16 g, 1 mmol), sodium ascorbate (2 g, 10 mmol), and 30 ml of tetrahydrofuran. The mixture was heated to 70°C and reacted for 48 hours. 100 ml of dichloromethane and 100 ml of water were added, followed by extraction with 75 ml of 1 mol / L hydrochloric acid solution. The organic phase was then extracted with 75 ml of 1 mol / L ammonia solution. The organic phase was dried over anhydrous magnesium sulfate, dried by spin drying, and filtered through a column to yield 0.58 g of a pale yellow solid (76% yield).

[0068] Under argon protection, 4,4'-(((2,5-dibromo-1,4-phenylene)bis(oxy))bis(methylene))bis(1-dodecyl-1H-1,2,3-triazole) (92 mg, 0.12 mmol), 2,2'-(9,9-bis(6-bromohexyl)-9H-fluorene-2,7-diyl)bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolane) (90 mg, 0.12 mmol), 5 mg of tetrakis(triphenylphosphine)palladium(0), 10 ml of toluene, 0.5 ml of methyltrioctylammonium chloride, and 1.5 ml of 2 mol / L potassium carbonate solution were added to the reaction flask, heated to 110°C, and reacted for 72 hours. After extraction with dichloromethane, the mixture was dried over anhydrous magnesium sulfate and then spin-dried. A minimum amount of dichloromethane was added to dissolve the mixture, and the mixture was added dropwise into 200 ml of methanol to precipitate the mixture. The mixture was filtered and dried in vacuo to obtain 93 mg of a light yellow solid with a yield of 57%.

[0069] Example 2

[0070] 10ml N,N-dimethylformamide was selected as the solvent, 1mg of polymer sensor probe and 1mg of hydroxylated single-walled carbon nanotubes were added, and the mass ratio of sensor probe to carbon nanotube material was 1:1. After 5 minutes of ultrasonic mixing, a uniform mixture was obtained. The scanning electron microscope image of the pure carbon nanotube material is shown below. Figure 5 As shown, the scanning electron microscope image of the carbon nanotube material after attaching the sensor probe is as follows Figure 6 As shown, it can be seen that after the polymer sensing probe is attached through non-covalent interaction, the carbon nanotubes are dispersed more evenly, which is beneficial to improving the sensing effect.

[0071] Example 3

[0072] The manufacturing process of the sensor is as follows: First, an interdigital electrode is provided as a test electrode, and its structural formula is as follows: Figure 7As shown, a represents a glass substrate, b represents titanium tungsten gold, titanium tungsten gold is deposited on the glass substrate a, b forms the interdigitated electrode, the suspension in Example 2 is applied to the test electrode with a pipette gun, and a polymer-based sensor is obtained after the solvent evaporates. The schematic diagram of the test electrode structure is shown in FIG. Figure 7 shown.

[0073] Under room temperature conditions, in an atmospheric environment, a series of nitrogen dioxide test gases with different concentrations are prepared by mixing standard nitrogen dioxide gas with air, with volume fractions of 100ppb, 200ppb, 500ppb, 1ppm, 5ppm, and 10ppm, respectively. The sensor device is placed in the cavity, the device is connected to the circuit and the resistance acquisition equipment, and the resistance change is monitored. Sensitivity (response intensity) S = ΔG / G0 (S is the sensitivity, G0 is the resistance at the start time, and ΔG is the resistance value at the end time minus the resistance value at the start time). Continuously introduce about 100ml of a certain concentration of nitrogen dioxide test gas, and it can be observed that the resistance value drops significantly. After waiting for the resistance value to recover, continue to introduce a certain concentration of nitrogen dioxide test gas, and repeat this process to obtain a sensing curve of resistance value changing with time. Figure 8 As shown, it can be seen that the sensor can effectively sense nitrogen dioxide gas. When the nitrogen dioxide gas concentration is 100ppb, the resistance value drops from 244Ω to 226Ω, and the resistance value change rate is -7%, which has a good test effect.

[0074] Example 4

[0075] Considering that the sensing test of nitrogen dioxide gas in the atmospheric environment will be interfered by a variety of common gases in the air, the sensing test of high concentration interfering gases was carried out in the same manner as in Example 3. The interfering gases were sulfur dioxide, carbon dioxide, carbon monoxide gas and air with a volume fraction of 1000ppm. Figure 9 As shown, it can be seen that the sensor has strong anti-interference ability and good selectivity to these common interfering gases.

Claims

1. A polymer represented by the following general formula I, characterized in that: （I）； Where Ar1 is 、 At least one of; Said Ar2 is 、 At least one of; Wherein R1 is a bromoalkyl group; k is the number of repeating units of the polymer, which is a natural number between 1 and 1000.

2. The polymer according to claim 1, characterized in that The R1 is C n H 2n+1-m Brm, n is a positive integer from 1 to 20, and m is a positive integer from 1 to 3; The R2 is selected from a hydrogen atom, an alkyl group, a substituted alkyl group, an ester group, an acyl group, an alkoxy group or a cyano group; wherein the substituent in the substituted alkyl group includes at least one of a hydroxyl group and an amino group.

3. The polymer according to claim 1, characterized in that The polymer is 。 4. A method for preparing the polymer according to claim 1, comprising: A fluorene monomer having a bromoalkyl group substituted in the 9,9-position side chain and substituted with a diboron ester in the 2,7-position or a carbazole monomer having a bromoalkyl group substituted in the N-position side chain and substituted with a triazole functional group in the 1,4-position side chain and substituted with a bromo benzene ring monomer in the 2,5-position is subjected to a Suzuki coupling reaction to obtain a polymer.

5. The preparation method according to claim 4, comprising: (1) 2,7-dibromofluorene or carbazole is reacted with a long-chain bromohydrocarbon monomer to obtain a fluorene or carbazole monomer compound with R1 as a side chain, which is then reacted with bis-pinacol diboron to obtain a monomer compound with boron esters at both ends; (2) 2,5-dibromo-1,4-benzenediol is reacted with 3-bromo-1-trimethylsilyl-1-propyne to obtain a monomer compound with bromine at both ends, which is then subjected to a deprotection reaction to obtain a monomer compound with an alkynyl terminal. The monomer compound with an alkynyl terminal is then reacted with a monomer with an azide group through a click reaction to obtain a monomer with bromine at both ends and a triazole functional group on the side chain; (3) A monomer compound with boron ester at both ends is polymerized with a monomer with bromine at both ends and a triazole functional group on the side chain to obtain a polymer.

6. A sensing material, characterized in that: The sensing material comprises the polymer and carbon nanotubes according to any one of claims 1 to 3.

7. The sensing material according to claim 6, characterized in that: The carbon nanotubes are one or more of single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes, hydroxylated carbon nanotubes, carboxylated carbon nanotubes, amidated carbon nanotubes, and graphitized carbon nanotubes; The mass ratio of the polymer to the carbon nanotubes is 1:1 to 1:

10.

8. A sensor device, characterized in that: The sensor device includes an electrode with the sensing material according to claim 6 provided on its surface.

9. A method for preparing a sensor device, comprising: The polymer described in any one of claims 1 to 3 is attached to the carbon nanomaterial through non-covalent interaction, coated on the electrode surface and dried to obtain a sensor.

10. Use of the sensing material according to claim 6 or the sensing device according to claim 8 in identifying, detecting and monitoring nitrogen dioxide (NO2) gas.

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