A quinacridone-based polymer thin film, a preparation method, applications and an acid detection method

Abstract

The present application relates to the field of organic chemistry, and provide a kind of quinacridone-based polymer film, preparation method, application and acidic detection method.The polymer film, preparation method, application and acidic detection method provided by the present application, because monomer is quinacridone as acidic detection response unit, combine quinacridone with polymerizable group carbazole, by screening, introduce the optimal alkyl chain length, avoid the influence of the conjugation effect between quinacridone and carbazole on acidic detection, so, the film can be polymerized at room temperature, preparation process is simple, can save energy, has good stability and acidic detection property, can be recycled, has sensitivity and economy in acidic detection.

Description

Technical Field

[0001] The present invention relates to the field of organic chemistry, and in particular to a quinacridone-based polymer film, a preparation method, an application and an acidity detection method. Background Art

[0002] In agriculture, industry, environmental protection, and other production processes, it is often necessary to measure the pH of solutions or gases such as water, fuel gas, reagents, and reaction solutions to guide subsequent work. In the prior art, pH test paper is commonly used to test the acidity or alkalinity of solutions or gases. However, pH test paper is not reusable, is complex to handle after use, and can easily pollute the environment.

[0003] Organic dyes have been used in various scientific fields, such as medicine, physics, and chemistry, to produce strong color changes due to their rich and bright colors. Quinacridone is a readily available class of organic pigments with hues mainly in red and purple. It has excellent fastness properties, especially light fastness and heat fastness, and is heat-resistant to nearly 300°C. Due to the presence of carbonyl groups on the conjugated skeleton of quinacridone, it can combine with hydrogen ions in acids to change its own color, making it an excellent acid detection material. However, quinacridone exists in the form of an extremely fine powder under normal conditions, has low solubility in water, and is highly reactive. It easily reacts with the solution or gas to be tested, such as nucleophilic substitution reactions, addition reactions, oxidation reactions, etc., making it difficult to realize its application in acid detection materials. Summary of the Invention

[0004] The present invention is made to solve the above-mentioned problems, and its purpose is to provide a quinacridone-based polymer film that can quickly and accurately detect the acidity of solutions or gases.

[0005] Prior to the present invention, in order to realize the application of quinacridone in the field of acid detection, the inventors attempted to chemically modify quinacridone through reactions such as acylation, alkylation, and amination to change its chemical and physical properties, and tried to use it directly in detection. However, this method is complicated to operate and is still difficult to handle after detection, making it inconvenient for detection.

[0006] The inventors also tried to attach quinacridone powder to other frameworks to prepare a composite material, but quinacridone powder is a free molecule without a fixed spatial structure and stable chemical bonds, making it difficult to directly combine with other framework materials to form a stable composite material.

[0007] The inventors attempted to process quinacridone molecules into films, enabling simple and intuitive acidity detection through color changes. However, because quinacridone molecules contain pyridine and aromatic rings, the processing process is prone to aggregation, accumulation, and crystallization, resulting in complex operations and poor film quality and performance.

[0008] The applicant previously developed a method for preparing a bifunctional electrochromic material based on quinacridone (CN114409647 B), a membrane material. The inventors then attempted to use this material for acid detection. However, due to the conjugation between quinacridone and carbazole, the material's acid detection performance was insensitive. The applicant was unsure whether a membrane material made from a quinacridone derivative and a carbazole-substituted monomer could be used for sensitive and stable acid detection.

[0009] During the research on quinacridone-based polymer films, the inventors found that changing the value of m in the polymerized monomer can give the film different properties and achieve different functions.

[0010] In a first aspect of the present invention, a quinacridone-based polymer film is provided for acid detection, wherein the polymer film is prepared from a monomer represented by formula (I):

[0011]

[0012] A second aspect of the present invention provides a method for preparing a quinacridone-based polymer film, comprising the following steps:

[0013] (1) subjecting quinacridone to an alkylation reaction to obtain a quinacridone derivative, wherein the quinacridone has a structural formula of formula (II), and the quinacridone derivative has a structural formula of formula (III);

[0014]

[0015] (2) allowing a quinacridone derivative to undergo a substitution reaction with carbazole to obtain a monomer, wherein the carbazole has a structural formula as shown in Formula (IV);

[0016]

[0017] (3) dissolving the monomer in a mixed solution of dichloromethane and acetonitrile, adding a supporting electrolyte, and performing electrochemical polymerization in a three-electrode system. The polymer film is formed by cyclic voltammetry.

[0018] The preparation method provided by the present invention may also have the following feature, wherein the substrate for the alkylation reaction in step (1) is 1,10-dibromodecane.

[0019] Due to the screening of the alkylation reaction substrate, the present invention avoids the influence of the conjugation between quinacridone and carbazole, thereby improving the acid detection performance of the film.

[0020] The preparation method provided by the present invention may also have the following feature, wherein the molar ratio of the 1,10-dibromodecane to the quinacridone is (2.5-5):1.

[0021] If the amount of 1,10-dibromodecane added is too small, a unilaterally substituted product will be generated. If the amount of 1,10-dibromodecane added is too large, the two bromine groups of 1,10-dibromodecane will replace the N position of quinacridone, forming a closed ring. Therefore, it is necessary to screen and control the molar ratio of 1,10-dibromodecane to quinacridone.

[0022] The preparation method provided by the present invention may also have the following feature, wherein the volume ratio of dichloromethane to acetonitrile in step (3) is (1.5-9):1, preferably (1.5-4.5):1.

[0023] Since the volume ratio of dichloromethane and acetonitrile in step (3) is controlled, the solubility of the solution is improved, the conductivity of the solution is increased, and the electrochemical polymerization film is easier to form.

[0024] The preparation method provided by the present invention may also have the following feature, wherein the concentration of the monomer solution in step (3) is 0.2 to 1.2 mg / mL.

[0025] Since the concentration of the monomer solution in step (3) is controlled, the solubility of the solution is improved.

[0026] The preparation method provided by the present invention may also have the following feature, wherein the supporting electrolyte in step (3) is one of lithium perchlorate and tetrabutylammonium hexafluorophosphate.

[0027] Due to the addition of supporting electrolyte, the ion migration rate of the solution is improved and the electrochemical polymerization potential is reduced.

[0028] The preparation method provided by the present invention may also have the following feature, wherein the voltage of the electrochemical polymerization in step (3) is 1.3 to 1.8V.

[0029] The preparation method provided by the present invention may also have the following feature, wherein the scanning speed in step (3) is 50 to 500 mV / s.

[0030] By controlling the voltage and scanning speed of electrochemical polymerization, damage to the film caused by excessively high voltage is avoided, and failure of film polymerization caused by excessively low voltage is also avoided.

[0031] A fourth aspect of the present invention provides an application of a quinacridone-based polymer film, characterized in that the polymer film is used for acid detection.

[0032] A fifth aspect of the present invention provides a method for detecting the acidity of a quinacridone-based polymer film, which has the following characteristics: the polymer film is placed in a solution or gas to be tested, and whether the solution or gas to be tested is acidic is determined based on the color change of the polymer film; the ultraviolet absorption spectrum of the polymer film is tested, and the hydrogen ion concentration of the solution or gas to be tested is determined based on the ultraviolet absorption spectrum.

[0033] The acidity detection method provided by the present invention may also have the following feature: when the polymer film turns purple, it can be determined that the solution or gas to be tested is acidic.

[0034] The acidity detection method provided by the present invention may also have the following feature: an alcohol solvent or acetonitrile is added to the solution to be tested before the test.

[0035] When alcohol solvents or acetonitrile are added to the solution to be tested, the film is well detected, the film changes color quickly, and the color change effect is uniform.

[0036] By implementing the above technical solution, the present invention has the following beneficial effects:

[0037] The polymer film provided by the present invention has good acid detection properties because the monomer uses quinacridone as the acid detection response unit and the optimal alkyl chain length is introduced through screening, thereby avoiding the influence of the conjugation between quinacridone and carbazole on acid detection.

[0038] The method for preparing the polymer film provided by the present invention combines quinacridone with the polymerizable group carbazole, so the present invention can prepare a polymer film with good stability.

[0039] The polymer film provided by the present invention is synthesized by screening the optimal polymer monomers and can be polymerized into a film at room temperature. Therefore, the film of the present invention is simple to operate during the preparation process, can save energy, and is economical.

[0040] The polymer film, application and detection method provided by the present invention have good stability, and the film properties are not affected after use. The film can restore its original color in the air. Therefore, the film of the present invention can be recycled and has sensitivity and economy in acid detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is the electrochemical polymerization curve of the corresponding monomer of the quinacridone-based polymer film in Example 2 of the present invention;

[0042] Figure 2 is the relationship between the absorbance at a wavelength of 600 nm and the hydrogen ion concentration of the quinacridone-based polymer film in Example 3 of the present invention;

[0043] Figure 3 is a comparison curve of the ultraviolet absorbance of the quinacridone polymer film before and after the test in Example 4 of the present invention;

[0044] Figure 4 1 is a comparison curve of the ultraviolet absorbance of the quinacridone-based polymer film before and after the recyclability test in Example 14 of the present invention;

[0045] Figure 5 The graph shows a change in ultraviolet absorbance of the quinacridone-based polymer film in Example 15 of the present invention in a 0.05 mol / L hydrochloric acid / acetonitrile solution. DETAILED DESCRIPTION

[0046] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is described in detail below with reference to embodiments and drawings.

[0047] Example 1: Preparation of quinacridone-based polymer monomers

[0048] (1) Add 20 mL of dimethyl sulfoxide, 0.31 g of quinacridone, 0.1 g of sodium hydroxide, 0.03 g of tetrabutylammonium bromide, and 1.2 g of 1,10-dibromodecane to a reaction vessel, and stir at room temperature for 24 hours. After the reaction, add 100 mL of water and filter to obtain an orange solid. The orange solid is dissolved in a small amount of dichloromethane and recrystallized by adding a large amount of ethyl acetate to obtain a quinacridone derivative (III).

[0049]

[0050] (2) Add 0.37 g of the quinacridone derivative of formula (III), 0.3 g of carbazole, 0.03 g of tetrabutylammonium bromide, and 9 mL of a 50% aqueous sodium hydroxide solution to a reaction vessel, and stir at room temperature for 24 hours. The reaction solution is extracted three times with water / dichloromethane, and then subjected to column chromatography with dichloromethane and petroleum ether (volume ratio 4:1) to obtain a polymer monomer (I), whose H NMR spectrum is 1 H NMR(600MHz, CDCl3)δ8.83(s,2H),8.63(dd,2H),8.12(d,4H),7.77–7.72(td,2H),7.49–7.45(m, 8H),7.34(t,2H),7.24(m,6H),4.52(t,4H),4.42(t,4H),2.08–1.99(m,8H),1.73–1.61(m,16H).

[0051]

[0052] Example 2: Preparation of quinacridone-based polymer films

[0053] 4.6 mg of the monomer represented by formula (I) was dissolved in 10 mL of a mixture of dichloromethane and acetonitrile, with a volume ratio of dichloromethane to acetonitrile of 7:3. 0.387 g of tetrabutylammonium hexafluorophosphate was added. In a three-electrode system, ITO was used as the working electrode, platinum wire was used as the counter electrode, and Ag / AgCl was used as the reference electrode. Electrochemical polymerization was carried out at room temperature and a voltage of 1.4 V with a scan rate of 100 mV / s. The film was polymerized by cyclic voltammetry. The electrochemical polymerization curve of the corresponding monomer of the quinacridone-based polymer film is shown in FIG. Figure 1 shown.

[0054] Example 3: Acidity Detection Method of Quinacridone-Based Polymer Film

[0055] Place the polymer film in the solution or gas to be tested and observe the color change of the polymer film. If the film turns purple, it means that the solution or gas to be tested is acidic. Test the ultraviolet absorption spectrum of the polymer film and judge the hydrogen ion concentration in the solution or gas to be tested based on the ultraviolet absorption spectrum. The relationship between the absorbance at a wavelength of 600nm and the hydrogen ion concentration of the quinacridone-based polymer film is as follows: Figure 2 shown.

[0056] Depend on Figure 2 It can be seen that the absorbance of the polymer film at a wavelength of 600 nm increases with the increase of hydrogen ion concentration. The hydrogen ion concentration in the solution or gas to be tested can be inferred by detecting the absorbance of the polymer film at a wavelength of 600 nm.

[0057] Example 4: Acidity Detection Method of Quinacridone-Based Polymer Film

[0058] Prepare a 0.05mmol / L hydrochloric acid solution as the test solution, add 5mL of acetonitrile to the test solution, place the polymer film in the solution or gas, observe the color change of the polymer film, the film quickly turns purple, and test the ultraviolet absorption spectrum of the polymer film. The ultraviolet absorbance comparison curve of the quinacridone polymer film before and after the test is as follows Figure 3 shown.

[0059] Depend on Figure 3 It can be seen that the UV absorbance curve of the polymer film changes significantly before and after the test, and the film can be used for acid detection.

[0060] Example 5: Screening of substrate ratios for quinacridone alkylation reactions

[0061] In this example, the polymer monomer was prepared according to the method in step (1) of Example 1, and the amount of the reaction substrate 1,10-dibromodecane was further screened.

[0062] Table 1 Reaction effect changes with the proportion of 1,10-dibromodecane

[0063] Serial number Mass of 1,10-dibromodecane (g) Equivalent (eq) Reaction effect 1 0.6 2 More unilateral substitution, low yield 2 0.75 2.5 Less unilateral substitution and high yield 3 0.9 3 Less unilateral substitution and high yield 4 1.2 4 Almost no unilateral substitution, high yield 5 1.5 5 Almost no unilateral substitution, high yield 6 1.8 6 Generates closed-ring product with low yield

[0064] As shown in Table 1, when the molar ratio of 1,10-dibromodecane to quinacridone is (2.5-3):1, the yield of the polymer monomer is high and the production of unilaterally substituted products is low. When the molar ratio of 1,10-dibromodecane to quinacridone is (3-5):1, almost no unilaterally substituted products are produced, resulting in a good reaction. Therefore, when preparing the polymer monomer, it is necessary to control the molar ratio of 1,10-dibromodecane to quinacridone to (2.5-5):1 to prevent the production of excessive unilaterally substituted products, which can reduce the yield.

[0065] Example 6: Solvent Screening for Preparation of Quinacridone-Based Polymer Films

[0066] In this example, a polymer film was prepared according to the method in Example 2, and the ratio of the reaction solvent was further screened.

[0067] Table 2 Reaction effect changes with solvent ratio

[0068]

[0069] As shown in Table 2, when the volume ratio of dichloromethane to acetonitrile is (1.5-9:1), the solution is essentially clear, and polymer films can be prepared. When the volume ratio of dichloromethane to acetonitrile is (1.5-4.5:1), the solution is essentially clear and conducts easily, making polymer film preparation easy. Therefore, when preparing polymer films, the volume ratio of dichloromethane to acetonitrile should be controlled within (1.5-9:1).

[0070] Example 7: Monomer Concentration Screening for Quinacridone-Based Polymer Film Preparation

[0071] In this example, a polymer film was prepared according to the method in Example 2, and the monomer concentration was further screened.

[0072] Table 3 Reaction effect changes with monomer concentration

[0073] Serial number Polymer monomer concentration (mg / mL) Reaction effect 1 0.2 The film surface is smooth and the thickness is thin 2 0.4 The film surface is smooth and the thickness is moderate 3 0.6 The film surface is smooth and the thickness is moderate 4 0.8 The film surface is smooth and the thickness is moderate 5 1.0 The film surface is smooth and thick 6 1.2 The film surface is slightly flat and thicker 7 1.4 The film surface is granular and thick

[0074] As shown in Table 3, polymer films can be prepared when the monomer concentration is 0.2-1.2 mg / mL. When the monomer concentration is 0.4-0.8 mg / mL, the prepared polymer film has a smooth surface, moderate thickness, and the reaction effect is optimal.

[0075] Example 8: Preparation of Quinacridone-Based Polymer Films and Screening of Monomer Polymerization Voltage

[0076] In this example, a polymer film was prepared according to the method in Example 2, and the monomer concentration was further screened.

[0077] Table 4 Reaction effect changes with polymerization voltage

[0078] Serial number Aggregation voltage (V) Reaction effect 1 1.2 Poor film forming properties 2 1.3 Good film forming properties, thinner film growth 3 1.4 Good film forming properties and uniform film growth 4 1.5 Good film forming properties and uniform film growth 5 1.8 Good film forming properties, but the film grows too thick and has poor stability

[0079] As shown in Table 4, when the polymerization voltage is 1.2-1.8 V, polymer films can be prepared. When the polymerization voltage is 1.4-1.5 V, the polymer film grows evenly during the preparation process and the reaction effect is optimal.

[0080] Example 9: Preparation of Quinacridone-Based Polymer Films Monomer Polymerization Scanning Speed ​​Screening

[0081] In this example, a polymer film was prepared according to the method in Example 2, and the monomer concentration was further screened.

[0082] Table 5: Changes in reaction effect with scanning speed

[0083] Serial number Scan speed (mV / s) Reaction effect 1 50 The film surface is rough and thick 2 100 The film surface is smooth and the thickness is moderate 3 300 The film surface is smooth and thin 4 500 Poor film forming properties, very thin film

[0084] It can be seen from Table 5 that when the scanning speed is 50-500 mV / s, polymer films can be prepared. When the scanning speed is 100-300 mV / s, the surface of the polymer film is flat. When the scanning speed is 300 mV / s, the surface of the polymer film is flat and smooth with moderate thickness, and the reaction effect is optimal.

[0085] Example 10: Screening of acidity detection conditions

[0086] This example further screens additives based on the acid detection method in Example 3. Acidic solutions of different concentrations are prepared, and quinacridone-based polymer films are placed in the acidic solutions to observe the film under different detection conditions.

[0087] Table 6 Acidity test of films with different additives

[0088]

[0089] Table 6 shows that when water is added as an additive, the polymer film fails to detect acidic solutions. However, when alcoholic solvents or acetonitrile are added, the polymer film can rapidly detect acidic solutions of varying concentrations, with uniform color change and excellent detection results. Therefore, when using polymer films for acidic detection, alcoholic solvents or acetonitrile must be added.

[0090] Example 11: Acid Gas Detection Effect Test

[0091] Measure 10 mL of acetic acid, hydrochloric acid, and sulfuric acid into a beaker and place the quinacridone-based polymer film on top of the acetic acid, hydrochloric acid, and sulfuric acid, respectively. The color change of the polymer film is as follows:

[0092] Table 7 Changes in the color of polymer films with acid types

[0093] Serial number Acid type Color Change 1 acetic acid The film turns purple and the color change effect is uniform 2 hydrochloric acid The film quickly turns purple and the color change effect is uniform 3 sulfuric acid The film turns purple and the color change effect is uniform

[0094] As shown in Table 7, the polymer film can detect various acidic gases, among which hydrochloric acid gas has the best detection effect.

[0095] Example 12: Recyclability test of quinacridone-based polymer films

[0096] The UV absorption spectrum of the quinacridone-based polymer film in its initial state was tested using a UV-visible spectrophotometer. The quinacridone-based polymer film was immersed in 0.02 mmol / L hydrochloric acid / acetonitrile solutions, and its UV absorption spectrum in the colored state was tested using a UV-visible spectrophotometer. Finally, the polymer film was taken out of the hydrochloric acid / acetonitrile solution, placed in the air, and after the color returned to its initial state, its UV absorption spectrum was tested again. The comparison curve of UV absorbance before and after the test is shown as follows: Figure 4 shown.

[0097] Depend on Figure 4 It can be seen that the UV absorbance curves of the polymer film before and after the test have a high degree of overlap, the properties of the film have not changed, and it can be reused.

[0098] Example 13: Stability test of quinacridone-based polymer films

[0099] The quinacridone-based polymer film was immersed in a 0.05 mmol / L hydrochloric acid / acetonitrile solution. After the film changed color, the UV absorption spectrum of the quinacridone-based polymer film in the colored state at 0 h was tested using a UV-visible spectrophotometer. After immersion for 96 h, the UV absorption spectrum of the quinacridone-based polymer film in the colored state at 96 h was tested using a UV-visible spectrophotometer. The comparison curve of UV absorbance before and after the test is shown as follows: Figure 5 shown.

[0100] Depend on Figure 5 It can be seen that after the polymer film is immersed for 96 hours, the ultraviolet absorbance of the colored polymer film does not change significantly, the film properties do not change, and the stability is good.

[0101] Comparative Example 1: Screening of quinacridone-based polymer monomers and films with different m values

[0102] According to the steps of Example 1, 1,4-dibromobutane, 1,6-dibromohexane and 1,10-dibromodecane were respectively selected to prepare polymer monomers with m=4, 6 and 10, and the monomer structures were shown in Formula (V).

[0103]

[0104] Polymer monomers with m=4, 6, and 10 are polymerized to form films respectively.

[0105] When m = 4, the same procedures as in Example 1 were followed, except that 1.2 g of 1,10-dibromodecane was replaced with 0.3 g of 1,4-dibromobutane. 3.8 mg of the polymer monomer was added to 10 mL of dichloromethane. The monomer had extremely poor solubility in dichloromethane and partially dissolved in the dichloromethane solvent after heating at 50°C. However, some solids remained insoluble, making electrochemical polymerization impossible.

[0106] When m = 6, the same procedures as in Example 1 were followed, except that 1.2 g of 1,10-dibromodecane was replaced with 0.3 g of 1,6-dibromohexane. 4.0 mg of the polymer monomer was dissolved in a 9:1 volume ratio mixture of dichloromethane and acetonitrile to prepare a 10 mL solution. 0.15 mg of 0.15 mol / L lithium perchlorate was added. The solution was placed on a heating plate and maintained at a constant temperature of 50°C to ensure the monomer's solubility in the mixed solvent. In a three-electrode system, ITO served as the working electrode, platinum wire as the counter electrode, and Ag / AgCl as the reference electrode. Polymerization films were formed by cyclic voltammetry.

[0107] When m=10, 4.6 mg of polymer monomer was dissolved in a mixture of dichloromethane and acetonitrile in a volume ratio of 7:3 to prepare a 10 mL solution, and 0.15 mg of 0.15 mol / L lithium perchlorate was added. At room temperature, a three-electrode system was used, with ITO as the working electrode, platinum wire as the counter electrode, and Ag / AgCl as the reference electrode, to form a film by cyclic voltammetry.

[0108] 0.05 mol / L hydrochloric acid was prepared to test the acidity of quinacridone-based polymer films with different m values. The test results are shown in the following table.

[0109] Table 8 Detection effects of different polymer films

[0110] Serial number Polymer monomer m value Acidity detection effect 1 4 Unable to form a film for acid detection 2 6 The film changes color slowly and unevenly 3 10 The film changes color quickly and evenly

[0111] In summary, the quinacridone-based polymer film with m=10 has milder preparation conditions and can be formed at room temperature than the film with m=6 in the prior art, and also has better acid detection effect, faster film detection speed, and uniform color change effect.

[0112] Comparative Example 2: Preparation of quinacridone-based polymer film when m=6

[0113] (1) Add 20 mL of dimethyl sulfoxide, 0.31 g of quinacridone, 0.1 g of sodium hydroxide, 0.03 g of tetrabutylammonium bromide, and 0.3 g of 1,6-dibromohexane to a reaction vessel, and stir at room temperature for 24 hours. After the reaction is completed, add 100 mL of water, filter and obtain an orange solid. The orange solid is dissolved in a small amount of dichloromethane and recrystallized by adding a large amount of ethyl acetate to obtain 0.1 g of quinacridone derivative (VI).

[0114]

[0115] (2) 0.31 g of the compound represented by formula (VI), 0.3 g of carbazole, 0.03 g of tetrabutylammonium bromide, and 9 mL of a 50% aqueous sodium hydroxide solution were added to a reaction vessel and stirred at room temperature for 24 hours. The reaction solution was extracted three times with water / dichloromethane and then subjected to column chromatography using dichloromethane and petroleum ether (volume ratio 8:1) to obtain 0.18 gm = 6 of polymer monomer (V). Its nuclear magnetic hydrogen spectrum is 1H NMR (600MHz, CDCl3) δ8.80 (s, 2H), 8.61 (dd, 2H), 8.11 (d, 4H), 7.76–7.72 (td, 2H), 7.47–7.44 (m, 8H), 7.32 (t, 2H), 7.23 (m, 6H), 4.50 (t, 4H), 4.40 (t, 4H), 2.02–1.96 (m, 8H), 1.70–1.60 (m, 8H).

[0116]

[0117] (3) 4.0 g of the monomer represented by formula (V) with m=6 was dissolved in 10 mL of a mixture of dichloromethane and acetonitrile, with a volume ratio of dichloromethane to acetonitrile of 7:3. 0.387 g of tetrabutylammonium hexafluorophosphate was added. In a three-electrode system, ITO was used as the working electrode, platinum wire was used as the counter electrode, and Ag / AgCl was used as the reference electrode. Electrochemical polymerization was carried out at room temperature and a voltage of 1.4 V, but no film could be formed.

[0118] The above embodiments are preferred examples of the present invention and are not intended to limit the scope of protection of the present invention.

Claims

1. A quinacridone-based polymer film for acid detection, characterized in that: The polymer film is prepared from the monomer represented by formula (I): （I）。 2. A method for preparing a quinacridone-based polymer film according to claim 1, characterized in that: The following steps are involved: (1) subjecting quinacridone to an alkylation reaction to obtain a quinacridone derivative, wherein the quinacridone has a structural formula of formula (II), and the quinacridone derivative has a structural formula of formula (III); (II) (III) (2) allowing a quinacridone derivative to undergo a substitution reaction with carbazole to obtain a monomer, wherein the carbazole has a structural formula as shown in Formula (IV); (IV) (3) The monomer is dissolved in a mixed solution of dichloromethane and acetonitrile, and a supporting electrolyte is added to perform electrochemical polymerization in a three-electrode system. The polymer film is formed by polymerization using cyclic voltammetry to obtain the polymer film.

3. The preparation method according to claim 2, characterized in that The alkylation reaction substrate in step (1) is 1,10-dibromodecane.

4. The preparation method according to claim 3, characterized in that The molar ratio of the 1,10-dibromodecane to the quinacridone is (2.5-5):

1.

5. The preparation method according to claim 2, characterized in that The volume ratio of dichloromethane to acetonitrile in step (3) is (1.5-9):

1.

6. The preparation method according to claim 5, characterized in that The volume ratio of dichloromethane to acetonitrile in step (3) is (1.5-4.5):

1.

7. The preparation method according to claim 2, characterized in that The concentration of the monomer in step (3) is 0.2-1.2 mg / mL.

8. A use of a quinacridone-based polymer film according to claim 1, characterized in that: The polymer film was used for acid detection.

9. A method for detecting acidity, characterized in that: The polymer film according to claim 1 is placed in a solution or gas to be tested, and whether the solution or gas to be tested is acidic is determined based on the color change of the polymer film. The ultraviolet absorption spectrum of the polymer film is tested, and the hydrogen ion concentration of the solution or gas to be tested is determined based on the ultraviolet absorption spectrum.

10. The acidity detection method according to claim 9, characterized in that: When the polymer film turns purple, it can be determined that the solution or gas to be tested is acidic.

11. The acidity detection method according to claim 9, wherein Before testing, an alcohol solvent or acetonitrile is added to the solution to be tested.

Images