A highly sensitive method for detecting early aging of aromatic polymers based on electrochemiluminescence

Abstract

A highly sensitive detection method for early aging of aromatic polymers based on electrochemiluminescence belongs to the field of aging detection of polymer materials. The present invention is based on the generation of carbon-centered free radicals and reactive oxygen free radicals by aging of aromatic polymers, and adopts electrochemiluminescence probes to achieve highly sensitive detection of the aging behavior of aromatic polymers through electrochemiluminescence signals. The method developed by the present invention is designed based on the universal principle of aromatic polymer aging reactions, and can realize the detection of aging behavior of various aromatic polymers, with the characteristics of rapid detection, accurate results, strong repeatability, high sensitivity, high practicality, and wide applicability. The present invention successfully realizes the early detection of aging of aromatic polymer materials and can be widely used in aging monitoring and failure analysis of materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of material aging detection, and in particular relates to a highly sensitive and rapid detection method for early aging behavior of aromatic polymer materials by using electrochemiluminescence. Background Art

[0002] Aromatic polymer materials have good rigidity due to the abundant benzene ring structure in their structure, and thus have a wide range of applications in electronic devices, optical instruments and other fields. However, due to the absorption of ultraviolet rays by benzene rings under light radiation, they become initiators of photodegradation of aromatic polymers. Therefore, aromatic polymers will generate carbon-centered free radicals under light radiation, which will further promote the generation of hydroxyl radicals (·OH) and superoxide anion radicals (O2 ·- ) and other highly active substances. Furthermore, the abundant benzene ring structure of aromatic polymers can stabilize carbon-centered free radicals, causing them to accumulate continuously, accelerating the chain reaction of polymer aging and degradation, leading to polymer structural degradation and performance failure. Therefore, it is urgent to accurately identify and evaluate the free radicals generated by polymers in the early stages of aging to reveal the degradation mechanism of polymers and enable the management of their use.

[0003] Traditionally, free radical detection during polymer aging has been based on electron spin resonance (ESR). However, ESR has limited sensitivity, requiring a long period of aging to detect significant signal changes, limiting its ability to detect polymer degradation at a high sensitivity and early stage.

[0004] Electrochemiluminescence (ECL) is widely used for evaluating material structures and reaction processes due to its high sensitivity. The method of the present invention uses ECL to perform early, highly sensitive detection of aromatic polymer aging. Aging of aromatic polymers generates carbon-centered free radicals and promotes the generation of reactive oxygen free radicals, resulting in a significant increase in the ECL signal. Therefore, the aging behavior of aromatic polymers can be detected with high sensitivity and accuracy through changes in the ECL signal. This method, with its high sensitivity and accuracy, can be used for early detection of aromatic polymer aging, providing new methods and strategies for studying its aging and degradation mechanisms. Summary of the Invention

[0005] Based on the principle that aromatic polymers generate carbon-centered free radicals during aging and promote the generation of reactive oxygen free radicals, in order to overcome the difficulties of the prior art, the present invention provides a highly sensitive early detection method for the aging behavior of aromatic polymers.

[0006] The technical solution of the present invention is: for the carbon-centered free radicals, hydroxyl free radicals, superoxide anion free radicals, etc. generated by aging of aromatic polymer materials under conditions of light, heat, stress, oxygen, etc., suitable electrochemiluminescence luminescent probes are selected, and an electrochemiluminescence workstation is used to perform high-sensitivity detection of the early aging behavior of aromatic polymers, revealing the various types of free radicals generated during the reaction process and their changes.

[0007] This method is suitable for detecting the aging behavior of various aromatic polymer materials under different aging conditions. The detection targets are carbon-centered free radicals, hydroxyl radicals, superoxide anion radicals, etc. It is applicable to the aging process of various aromatic polymers. The method has wide applicability to various materials and is easy to operate.

[0008] This method offers high sensitivity and can detect early aging behavior in aromatic polymers. Traditional methods for detecting chain scission in polymer materials require prolonged aging. This method effectively overcomes the limitations of traditional methods, such as poor sensitivity and limited practicality, offering advantages such as speed and reliability.

[0009] A highly sensitive detection method for aromatic polymer aging based on electrochemiluminescence is characterized by comprising the following steps:

[0010] (1) Preparation of aromatic polymer films

[0011] Aromatic polymer film materials are constructed using methods such as hot pressing, solvent evaporation, and blow molding. Taking the solvent evaporation method as an example, aromatic polymer particles can be dissolved in a certain concentration of organic solvent, transferred to a crystallization dish, and vacuum dried at 40-100°C.

[0012] (2) Aging of aromatic polymer films

[0013] Aromatic polymer films were aged using light, heat, water, oxygen, and stress. The wavelength of the light aging radiation was 280-400 nm, and the irradiation intensity was 0.5-2.0 W / m 2 , the temperature is 40-120℃, the oxygen content is 0%-100%, the water vapor content is 20%-80%, the stress is 0.5-10MPa; the aging treatment time is 0-10 days, and the polymer material is aged for different times;

[0014] (3) Deposition of aromatic polymer films on ITO electrodes

[0015] The ITO electrode is ultrasonically cleaned in water (30 minutes), ethanol (30 minutes), and water (15 minutes) in sequence. The aromatic polymer films before and after aging are dissolved, and then different ITO electrodes are immersed in the corresponding aromatic polymer film solutions before and after aging for 10-60 seconds, and after drying in air, the aromatic polymer films before and after aging are respectively obtained. The aging can be different aging conditions, such as different specific conditions such as light, heat, water, oxygen, stress, etc. in step (2), or even different parameters corresponding to different aging conditions, different aging times, etc.;

[0016] (4) Electrochemiluminescence test

[0017] The electrochemiluminescence test is performed using a three-electrode system, with a Pt electrode as a counter electrode, an Ag / AgCl electrode as a reference electrode, and an ITO electrode corresponding to the aromatic polymer film before and after deposition and aging as a working electrode. The test solution is an optical probe solution, and the electrochemiluminescence signal is recorded. For example, a 50-500 μmol / L luminol solution is selected, 0.1 mol / L phosphate buffered saline (PBS, pH = 7.4) is added, the scanning potential range is -0.8 to +1.2 V, the scanning rate is 0.02-0.2 V / s, and the electrochemiluminescence signal is recorded.

[0018] (5) Electrochemiluminescence signal analysis

[0019] The electrochemiluminescence (ECL) signals of aromatic polymer films aged under different conditions and for different times were analyzed.

[0020] By performing electrochemiluminescence detection and electrochemiluminescence signal analysis in different atmospheres (such as atmospheres with different oxygen contents, etc.), the corresponding atmosphere with strong signal is selected according to the change of electrochemiluminescence signal in different atmospheres; the electrochemiluminescence signal analysis includes analyzing the change of electrochemiluminescence signal of the aromatic polymer film before aging and after aging corresponding to different aging conditions. The aging condition of the aromatic polymer film can be judged and explored based on the comparison of the signal strength. The stronger the signal, the more serious the aging.

[0021] (6) Methyl blue was used to semi-quantitatively analyze the content of hydroxyl radicals in the system, and nitro blue tetrazolium chloride was used to semi-quantitatively analyze the content of superoxide anion radicals in the system, and then the generation of hydroxyl radicals and superoxide anion radicals and the changes in the content of hydroxyl radicals and superoxide anion radicals during the aging of aromatic polymers under different aging conditions were studied.

[0022] Highly sensitive detection of the early aging behavior of aromatic polymers is carried out, while further revealing the various types and changes of free radicals generated during the reaction process.

[0023] It also further includes the following:

[0024] Aging verification of aromatic polymer films: Gel permeation chromatography was used to determine the number average molecular weight and weight average molecular weight of the aged films to verify the structural deterioration and degradation behavior of the films.

[0025] The aromatic polymer selected in step (1) includes but is not limited to one or more of polystyrene, aromatic polycarbonate, aromatic polyamide, aromatic polyester, polyarylate, and aromatic ketone polymer.

[0026] Aromatic polymers generate carbon-centered free radicals after aging treatment. These carbon-centered free radicals promote the generation of reactive oxygen radicals such as hydroxyl radicals and superoxide anion radicals. The present invention uses an electrochemiluminescence probe to perform highly sensitive electrochemiluminescence detection of free radicals generated after aging of aromatic polymers. The method developed by the present invention is designed based on the universal principles of aromatic polymer aging reactions and can detect the aging behavior of various aromatic polymers. It has the characteristics of rapid detection, accurate results, strong repeatability, high sensitivity, high practicality, and wide applicability. The present invention successfully realizes the early detection of aging of aromatic polymer materials, providing a new means for revealing their aging mechanism and monitoring aging behavior. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The electrochemiluminescence signal value changes after multiple repeated scans using luminol as the electrochemiluminescence probe.

[0028] Figure 2 Electrochemiluminescence signal values ​​of polystyrene (PS) films after photoaging for 0, 2, 4, 6, 8, 10, and 12 hours.

[0029] Figure 3 The electrochemiluminescence signal of the PS film after photoaging for 0, 4, 8, and 12 hours varies with voltage.

[0030] Figure 4 The electrochemiluminescence signal values ​​of the PS film in air and nitrogen are those of the pristine and 12h photo-aged PS films.

[0031] Figure 5 Figure 2 shows the UV-visible absorption spectra of methylene blue and the statistics of the methylene blue quenching ratio of PS films without aging (pristine) and after 12h of photoaging (P-12h) after electrochemical testing.

[0032] Figure 6 Figure 2 shows the UV-visible absorption spectra and changes of nitro blue tetrazolium chloride on PS films without aging (pristine) and after 12h of light aging (P-12h) after electrochemical testing.

[0033] Figure 7 These are the electron spin resonance images of PS films that were not aged (pristine), photoaged for 12 h (P-12 h), photoaged for 3 days (P-3 d), and photoaged for 6 days (P-6 d). Figure (A) shows the determination of carbon-centered free radicals, Figure (B) shows the determination of hydroxyl radicals, and Figure (C) shows the determination of superoxide anion radicals.

[0034] Figure 8 The molecular weight change diagram of PS films without aging (pristine), photoaging for 12h (P-12h), photoaging for 3 days (P-3d) and photoaging for 6 days (P-6d). DETAILED DESCRIPTION

[0035] The present invention will be further described below with reference to the examples, but the present invention is not limited to the following examples.

[0036] Example 1:

[0037] (1) Preparation of polystyrene (PS) film

[0038] 4.00 g of PS particles were dissolved in dichloromethane with a concentration of 10 wt %, transferred to a 12 cm crystallization dish at room temperature, and dried in vacuum at 60° C. overnight to obtain a PS film.

[0039] (2) Photoaging of PS films

[0040] The prepared PS film was subjected to light aging treatment for different times on an accelerated aging device with an ultraviolet irradiation intensity of 1.0 W / m 2 , wavelength of 340 nm, temperature of 60 ° C. PS films were treated under light irradiation for 0-12 h, marked as Px h.

[0041] (3) Deposition of PS film on ITO electrode

[0042] The ITO electrode was ultrasonically cleaned in water (30 min), ethanol (30 min), and water (15 min). The PS film before and after photoaging was dissolved in 7.5 wt% dichloromethane. The ITO electrode was then immersed in the PS solution for 10 s and dried in air to obtain a PS film deposited on the ITO.

[0043] (4) Electrochemiluminescence test

[0044] A three-electrode system was used for electrochemiluminescence testing. The Pt electrode was used as the counter electrode, the Ag / AgCl electrode was used as the reference electrode, and the PS-deposited ITO electrode was used as the working electrode. The test solution was 300 μmol / L luminol solution, with 0.1 mol / L phosphate buffered saline (PBS, pH=7.4) added. The scanning potential range was -0.8 to +1.2 V, and the scanning rate was 0.1 V / s. The photomultiplier tube voltage of the electrochemiluminescence instrument was set to -900 V, and the electrochemiluminescence signal was recorded. Repeatability tests were performed, such as Figure 1 As shown in the figure, the electrochemiluminescence signal was stable after 9 cycles, indicating that the electrochemiluminescence analysis method used was highly accurate and reproducible.

[0045] (5) Analysis of electrochemiluminescence signals of photoaged PS films

[0046] Electrochemiluminescence was measured on PS films treated with light aging for different times, such as Figure 2 The normalized changes in the electrochemiluminescence signal are shown. After photoaging, the electrochemiluminescence signal of the PS membrane continuously increases, reaching twice the intensity of the untreated membrane after 12 hours of treatment, demonstrating that electrochemiluminescence can be used to monitor the photoaging behavior of PS membranes.

[0047] The electrochemiluminescence-voltage change diagram is analyzed, such as Figure 2 As shown, it can be observed that an electrochemical oxidation peak is generated at about 0.8 V, which is attributed to the oxidation peak of the probe molecule luminol.

[0048] (6) Analysis of the electrochemiluminescence enhancement principle of photo-aged PS films

[0049] By analyzing the electrochemiluminescence signal of PS film in different atmospheres, the principle of electrochemiluminescence enhancement of PS film after light aging was explored. Figure 3 As shown, the signal values ​​of the unaged (pristine) PS film and the PS film after 12 hours of light aging (P-12h) are higher in air, but significantly decrease in nitrogen, indicating the significant influence of oxygen on the electrochemiluminescence signal. Specifically, the signal value of the PS film P-12h in nitrogen is quenched by 96% compared to that in air.

[0050] Methyl blue (3 mg / L) was used to semi-quantitatively analyze the content of hydroxyl radicals in the system and its absorbance was calculated. The results showed that the degradation effect of methyl blue by P-12h after aging was better ( Figure 5 ), indicating that it produces more hydroxyl radicals. Nitro blue tetrazolium chloride (5mmol / L) was used to semi-quantitatively analyze the content of superoxide anion radicals in the system, and its absorbance was calculated. The results showed that the absorbance obtained after aging P-12h was higher, about 0.09 ( Figure 6), indicating that it produces more superoxide anion radicals.

[0051] The above results show that the PS film produces a large number of active oxygen free radicals under light treatment, which directly leads to a significant increase in the electrochemiluminescence signal.

[0052] (7) Free radical verification of photo-aged PS films

[0053] 150 mg of PS film was cut into pieces and placed in a quartz tube for electron spin resonance measurement of the solid sample. The carbon-centered free radical was detected at a g value of 2.004. However, no signal was detected for the early-aged PS film; a weak signal appeared after 3 days of aging, and a significant signal was not detected until 6 days of aging ( Figure 7 A) The above results indicate that carbon-centered free radicals are generated in the aged PS film, but due to the limited sensitivity of electron spin resonance, they can only be detected after long-term aging.

[0054] DMPO water or DMPO / DMSO solution was further used to capture OH or O2 ·- , and was measured by electron spin resonance spectroscopy. ·OH or O2 can be detected in the PS film after aging for 12 hours. ·- , verifying the accuracy of electrochemiluminescence detection.

[0055] Therefore, we can infer that the carbon-centered free radicals generated by the aging of the PS film exist and promote the formation of OH or O2 ·- The generation of luminol leads to enhanced luminescence, showing an increasing electrochemiluminescence signal, which realizes the early and highly sensitive detection of the photoaging behavior of the PS film.

[0056] (8) Aging verification of PS film

[0057] The number average molecular weight and weight average molecular weight of the aged PS membrane were further determined by gel permeation chromatography. Figure 8 As shown in the figure, no molecular weight change was detected in the first 12 hours of aging. However, the change in molecular weight after aging could be determined by gel permeation chromatography after 3-6 days of aging. These results indicate that photoaging treatment causes structural degradation and degradation of the PS membrane.

Claims

1. A method for detecting early aging of aromatic polymers based on electrochemiluminescence, characterized in that: The following steps are involved: (1) Preparation of aromatic polymer films; (2) Aging of aromatic polymer films; (3) Deposition of aromatic polymer films on ITO electrodes; The ITO electrode was ultrasonically cleaned in water for 30 min, in ethanol for 30 min, and in water for 15 min. The aromatic polymer film before and after photoaging was dissolved in 7.5 wt% dichloromethane. The ITO electrode was then immersed in the aromatic polymer film solution for 10 s and dried in air to obtain an aromatic polymer film deposited on the ITO. (4) Electrochemiluminescence test; The electrochemiluminescence test was performed using a three-electrode system, with a Pt electrode as the counter electrode, an Ag / AgCl electrode as the reference electrode, and an ITO electrode on which the aromatic polymer film was deposited before and after aging in step (3) as the working electrode. The test solution was a 50-500 μmol / L luminol solution, with 0.1 mol / L phosphate buffered saline added. The scanning potential range was −0.8 to +1.2 V, and the scanning rate was 0.02 to 0.2 V / s. The electrochemiluminescence signal was recorded. (5) Electrochemiluminescence signal analysis; The electrochemiluminescence (ECL) signals of aromatic polymer films aged for different times under different conditions were analyzed. By conducting electrochemiluminescence detection and electrochemiluminescence signal analysis in different atmospheres, the corresponding atmosphere with strong signal is selected according to the change of electrochemiluminescence signal in different atmospheres; the electrochemiluminescence signal analysis includes analyzing the change of electrochemiluminescence signal of the aromatic polymer membrane before aging and after aging under different aging conditions, and the aging of the aromatic polymer membrane is explored based on the comparison of signal strength. The stronger the signal, the more serious the aging. (6) Methyl blue was used to semi-quantitatively analyze the content of hydroxyl radicals in the system, and nitro blue tetrazolium chloride was used to semi-quantitatively analyze the content of superoxide anion radicals in the system. The generation of hydroxyl radicals and superoxide anion radicals as well as the changes in the content of hydroxyl radicals and superoxide anion radicals during the aging of aromatic polymers under different aging conditions were studied. The method also includes the following steps: aging verification of the aromatic polymer film, using gel permeation chromatography to measure the number average molecular weight and weight average molecular weight of the aged film to verify the structural deterioration and degradation behavior of the film.

2. The method according to claim 1, characterized in that Step (1) Preparation of aromatic polymer film: constructing aromatic polymer film material by hot pressing, solvent evaporation or blow molding.

3. The method according to claim 2, characterized in that When using the solvent evaporation method, aromatic polymer particles are dissolved in an organic solvent, transferred to a crystallizing dish, and dried under vacuum at 40-100 ºC.

4. The method according to claim 1, wherein Step (2) Aging of the aromatic polymer film: The aromatic polymer film is aged by light, heat, water, oxygen, and stress, wherein the light radiation wavelength is 280-400 nm and the irradiation intensity is 0.5-2.0 W / m 2 , temperature is 40-120 ºC, oxygen content is 0%-100%, water vapor content is 20%-80%, and stress is 0.5-10MPa.

5. The method of claim 1, wherein the aromatic polymer comprises a polystyrene film.

6. The method according to any one of claims 1 to 5, applied to aging monitoring and failure analysis of materials.

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