A tetraphenyl ethene-based fluorescent monomer, and a preparation method and application thereof

Abstract

The application discloses a tetraphenyl ethylene-based fluorescent monomer and a preparation method and application thereof, and belongs to the technical field of polymer light-emitting materials.The application connects a tetraphenyl ethylene group containing an aggregation-induced emission active group with a specific polymer skeleton to prepare a fluorescent monomer.The fluorescent polymer prepared by using the fluorescent monomer and a specific polymerization monomer can be used for detecting copper ions, and has high sensitivity and good repeatability during detection, and visual observation can be realized.

Description

Technical Field

[0001] This invention belongs to the field of polymer luminescent materials technology, specifically relating to a tetraphenylethylene-based fluorescent monomer, its preparation method, and its application. Background Technology

[0002] In recent years, with the vigorous development of science and technology, fluorescence sensing technology has been widely studied due to its high sensitivity, good selectivity, simple operation, low cost, high resolution, and ability to achieve rapid in-situ online detection in vivo. Fluorescent monomers exhibit obvious fluorescence emission or quenching when exposed to ultraviolet lamps, making this method relatively simple and fast. Fluorescence sensing technology is also widely used in important fields such as environmental monitoring, ion and small molecule detection, bioimaging, and medical diagnosis.

[0003] Copper is widely used in all aspects of life, and it usually undergoes uniform corrosion during use. However, even uniform corrosion in printed circuit boards (PCBs) with copper as the substrate can have a significant impact on the entire board. To address this issue, researchers such as M. Schwind, W. Cheng, and K. Habib have used traditional techniques such as nanoplasma sensing (Journal of the Electrochemical Society, 160(2013)C487-C492), electrochemical characterization (International Journal of Electrochemical Science, 14(2019)4254-4263), and holographic interferometry (Corrosion Science, 40(1998)1435-1440) to monitor the early stages of copper corrosion in PCBs. Although these methods provide accurate results, most have certain limitations; for example, electrochemical characterization and holographic interferometry are complex and cumbersome to use, requiring long detection cycle times. Therefore, these traditional methods cannot provide a quick and simple inspection of localized copper substrate corrosion areas in PCBs. Scholar Guo H (ACS Applied Materials & Interfaces, 2023) proposed developing a reusable metal surface corrosion detection sensor by combining fluorescent monomers with hydrogels. This sensor can detect trace corrosion by detecting iron ions released from the environment, with a detection limit as low as 10. - 5 However, this sensor still requires an ultraviolet lamp for auxiliary detection and cannot achieve direct visual detection.

[0004] To address the shortcomings of the aforementioned methods for detecting copper ions, the search for a copper ion-responsive fluorescent polymer with high sensitivity, good repeatability, and visual observation capability is currently a key research focus in the field of polymer luminescent materials. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a fluorescent monomer based on tetraphenylethylene, its preparation method and application. The fluorescent polymer obtained by the fluorescent monomer can be used to detect copper ions, and the detection has high sensitivity and good repeatability, and can be visually observed.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides a fluorescent monomer based on tetraphenylethylene, the structural formula of which is shown in formula (Ⅰ):

[0008]

[0009] The structure of R is selected from the following formulas (II), (III), (IV), (V), (VI) or (VII):

[0010]

[0011] Where n has a value between 0 and 20.

[0012] The fluorescent monomer of the present invention contains an aggregation-induced luminescence active group, tetraphenylethylene group, which is grafted onto a polymer backbone of formula (II), (III), (IV), (V), (VI) or (VII). The fluorescent polymer obtained by the fluorescent monomer under the above conditions can be used to detect copper ions, and the detection has high sensitivity and good repeatability, and can be visually observed.

[0013] In a preferred embodiment of the tetraphenylethylene-based fluorescent monomer of the present invention, R is of formula (V) and the value of n is 10.

[0014] In a second aspect, the present invention provides a method for preparing a tetraphenylethylene-based fluorescent monomer as described in the first aspect, the method comprising the following steps:

[0015] S1. A solution of 4-hydroxybenzophenone, a solution of 4,4'-dibromobenzophenone, and a catalyst were reacted under nitrogen atmosphere, followed by purification by silica gel column chromatography to obtain product 1.

[0016] S2. The product 1 obtained in step S1 is reacted with 3-vinylpyridine and a catalyst in nitrogen, and then purified by silica gel chromatography to obtain product 2.

[0017] S3. The product 2 from step S2 is reacted with the brominated raw material and the catalyst in nitrogen, and then purified by silica gel column chromatography to obtain the tetraphenylethylene-based fluorescent monomer.

[0018] In a preferred embodiment of the method for preparing tetraphenylethylene-based fluorescent monomers according to the present invention, in step S1, the molar ratio of 4-hydroxybenzophenone solution to 4,4'-dibromobenzophenone solution is 4-hydroxybenzophenone solution: 4,4'-dibromobenzophenone solution = 1-10:1.

[0019] As a more preferred embodiment of the method for preparing tetraphenylethylene-based fluorescent monomers according to the present invention, in step S1, the molar ratio of 4-hydroxybenzophenone solution and 4,4'-dibromobenzophenone solution is 4-hydroxybenzophenone solution: 4,4'-dibromobenzophenone solution = 2-5:1.

[0020] In the most preferred embodiment of the method for preparing tetraphenylethylene-based fluorescent monomers according to the present invention, in step S1, the molar ratio of 4-hydroxybenzophenone solution to 4,4'-dibromobenzophenone solution is 3:1.

[0021] Through numerous inventive experiments, the inventors discovered that the 4-hydroxybenzophenone solution and the 4,4'-dibromobenzophenone solution of the present invention, under the above molar ratio conditions, can ensure the complete polymerization reaction and make the products easier to separate; especially under the optimal conditions, the separation effect is the best.

[0022] In a preferred embodiment of the method for preparing tetraphenylethylene-based fluorescent monomers according to the present invention, in step S1, the molar concentration of the 4-hydroxybenzophenone solution is 50-200 mmol / L.

[0023] In a more preferred embodiment of the method for preparing tetraphenylethylene-based fluorescent monomers according to the present invention, the molar concentration of the 4-hydroxybenzophenone solution is 105 mmol / L.

[0024] In a preferred embodiment of the method for preparing tetraphenylethylene-based fluorescent monomers according to the present invention, in step S1, the catalyst is zinc, titanium tetrachloride, or tetrahydrofuran.

[0025] In a preferred embodiment of the method for preparing tetraphenylethylene-based fluorescent monomers according to the present invention, in step S2, the molar ratio of product 1 to 3-vinylpyridine is product 1:3-vinylpyridine = 1:1-10.

[0026] In a more preferred embodiment of the method for preparing tetraphenylethylene-based fluorescent monomers according to the present invention, in step S2, the molar ratio of product 1 to 3-vinylpyridine is product 1:3-vinylpyridine = 1:1-5.

[0027] In the most preferred embodiment of the method for preparing tetraphenylethylene-based fluorescent monomers according to the present invention, in step S2, the molar ratio of product 1 to 3-vinylpyridine is product 1:3-vinylpyridine = 1:3.

[0028] Through numerous inventive experiments, the inventors discovered that under the above molar ratio conditions, the polymerization reaction of product 1 and 3-vinylpyridine can be completed, and the products are easier to separate; especially under the optimal conditions, the separation effect is the best.

[0029] In a preferred embodiment of the method for preparing tetraphenylethylene-based fluorescent monomers according to the present invention, in step S2, the catalyst is palladium acetate (Pd(OAc)2), triethylamine, tripotassium phosphate, or N,N-dimethylformamide.

[0030] In a preferred embodiment of the method for preparing tetraphenylethylene-based fluorescent monomers according to the present invention, in step S3, the brominated raw material is selected from the following formulas (VIII), (IX), (X), (XI), (XII), or (XIII):

[0031]

[0032] Where the value of n is between 1 and 20.

[0033] In a more preferred embodiment of the preparation method of the tetraphenylethylene-based fluorescent monomer of the present invention, the brominated raw material is of formula (XII).

[0034] In the most preferred embodiment of the method for preparing the tetraphenylethylene-based fluorescent monomer of the present invention, the brominated raw material is 11-bromoundec-1-ene.

[0035] In a preferred embodiment of the method for preparing tetraphenylethylene-based fluorescent monomers according to the present invention, in step S3, the molar ratio of product 2 to brominated raw material is product 2:brominated raw material = 1:1-10.

[0036] In a more preferred embodiment of the preparation method of tetraphenylethylene-based fluorescent monomers of the present invention, in step S3, the molar ratio of product 2 to brominated raw material is product 2:brominated raw material = 1:1-5.

[0037] In the most preferred embodiment of the preparation method of tetraphenylethylene-based fluorescent monomer of the present invention, in step S3, the molar ratio of product 2 to brominated raw material is product 2:brominated raw material = 1:3.

[0038] Through numerous creative experiments, the inventors discovered that under the above molar ratio conditions, the product 2 of this invention and the brominated raw material can achieve a high conversion rate and easy product separation in the preparation process of the fluorescent monomer; especially under optimal conditions, the reaction conversion rate is the highest.

[0039] In a preferred embodiment of the method for preparing tetraphenylethylene-based fluorescent monomers according to the present invention, the catalyst in step S3 is potassium carbonate or acetone.

[0040] Thirdly, the present invention provides a fluorescent polymer, which is prepared by means of a fluorescent monomer as described in the first aspect.

[0041] As a preferred embodiment of the fluorescent polymer of the present invention, the structure of the fluorescent polymer is shown in formula (XIV):

[0042]

[0043] Wherein, R represents acrylic acid group;

[0044] n1:n2:n3=1-99.99:1-99.99:0-20.

[0045] In a more preferred embodiment of the fluorescent polymer of the present invention, R is acrylic acid.

[0046] In a more preferred embodiment of the fluorescent polymer of the present invention, n1:n2:n3 = 1:0.3:0.0015.

[0047] The fluorescent polymer of this invention is formed by free radical copolymerization of the aforementioned fluorescent monomer and polymerization monomer; the fluorescent polymer is responsive to copper ions in the environment; when the concentration of copper ions in the environment reaches 10... -4 When M is reached, the fluorescent polymer exhibits a fluorescence quenching effect, changing its color from yellow to green. The dynamic hydrogen bonds present in the three-dimensional network of the fluorescent polymer of this invention provide it with good adhesion and reusability. The fluorescent polymer can perform in-situ detection of printed circuit boards with localized surface damage, providing early warning of localized corrosion.

[0048] Fourthly, the present invention provides a method for preparing the fluorescent polymer, the method comprising the following steps:

[0049] A1. The fluorescent monomer as described in the first aspect is mixed with the polymerization monomer, initiator and crosslinking agent in an organic solvent and subjected to a free radical copolymerization reaction to obtain a polymer solution.

[0050] A2. The polymer solution described in step A1 is transferred to a solvent exchange solution for immersion. After solvent exchange is completed, a fluorescent polymer is obtained.

[0051] The polymerization monomer is of formula (XV) or a combination of formulas (XV) and (XVI):

[0052]

[0053] In a preferred embodiment of the preparation method of the fluorescent polymer of the present invention, in step A1, when the polymerization monomer is a combination of formula (XV) and formula (XVI), the molar ratio of formula (XV), formula (XVI) monomer and fluorescent monomer is formula (XV): formula (XVI) monomer: fluorescent monomer = 600-900:100-400:1.

[0054] As a more preferred embodiment of the preparation method of the fluorescent polymer of the present invention, the molar ratio of the monomers of formula (XV), formula (XVI) and fluorescent monomer is 800:100-200:1 for monomer of formula (XV): monomer of formula (XVI): fluorescent monomer.

[0055] In a preferred embodiment of the preparation method of the fluorescent polymer of the present invention, in step A1, when the monomer of the polymerization reaction is formula (XV), the molar ratio of formula (XVI) and fluorescent monomer is formula (XV): fluorescent monomer 700-1000:1.

[0056] As a more preferred embodiment of the preparation method of the fluorescent polymer of the present invention, the molar ratio of formula (XV) and fluorescent monomer is formula (XV): fluorescent monomer 1000:1.

[0057] Through numerous creative experiments, the inventors discovered that under the aforementioned molar ratio conditions, the transmittance of the fluorescent polymer can be improved, and the detection performance of the fluorescent polymer for copper ions can be made more accurate and sensitive.

[0058] In a preferred embodiment of the preparation method of the fluorescent polymer of the present invention, the molar concentration of the monomer in the polymerization reaction is 1-5.0 mol / L, preferably 2 mol / L.

[0059] In a preferred embodiment of the preparation method of the fluorescent polymer of the present invention, in step A1, the crosslinking agent is polyethylene glycol diacrylate.

[0060] In a more preferred embodiment of the preparation method of the fluorescent polymer of the present invention, the molecular weight of the polyethylene glycol diacrylate is 200-1000, preferably 200.

[0061] In a preferred embodiment of the preparation method of the fluorescent polymer of the present invention, in step A1, the molar concentration of the crosslinking agent is 0%-2% of the molar concentration of the monomer in the polymerization reaction, preferably 0.2%.

[0062] In a preferred embodiment of the preparation method of the fluorescent polymer of the present invention, in step A1, the initiator is a photoinitiator, a thermal initiator, a redox initiator, or an anaerobic polymerization initiator. In the present invention, the selection of the initiator is determined by the initiation conditions of the polymerization reaction in step A1. If ultraviolet light irradiation is used as the initiation condition, a photoinitiator is used; if microwave or gamma-ray irradiation is used, no initiator is required; if a heating method is used, a thermal initiator is used; if an anaerobic polymerization method is used, an anaerobic polymerization initiator is used.

[0063] In a more preferred embodiment of the preparation method of the fluorescent polymer of the present invention, the initiator is an oxygen-free polymerization initiator.

[0064] In the most preferred embodiment of the preparation method of the fluorescent polymer of the present invention, the oxygen-free polymerization initiator is potassium persulfate or tetramethylethylenediamine.

[0065] In a preferred embodiment of the preparation method of the fluorescent polymer of the present invention, in step A1, the molar concentration of the initiator is 0.01%-5% of the molar concentration of the monomer in the polymerization reaction, preferably 1%.

[0066] In a preferred embodiment of the preparation method of the fluorescent polymer of the present invention, in step A1, the organic solvent includes at least one selected from methanol, ethanol, N,N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, butanone, cyclohexanone, ethyl formate, tetrahydrofuran, dioxane, acetone, tetrachloroethane, propionitrile, pyridine, cyclohexanol, n-butanol, isopropanol, n-propanol, acetonitrile, dimethylacetamide, acetic acid, ethylene carbonate, malononitrile, ethylene glycol, glycerol, and formamide; preferably N,N-dimethylformamide or dimethyl sulfoxide, more preferably N,N-dimethylformamide.

[0067] In a preferred embodiment of the preparation method of the fluorescent polymer of the present invention, in step A1, the initiation conditions for the free radical copolymerization reaction are oxygen-free, ultraviolet light, microwave, gamma ray irradiation or heating.

[0068] As a more preferred embodiment of the preparation method of the fluorescent polymer of the present invention, when the initiation condition is ultraviolet light, the ultraviolet light irradiation time is 6-12h, preferably 8h.

[0069] As a more preferred embodiment of the preparation method of the fluorescent polymer of the present invention, the initiation conditions are heating at a temperature of 60-100°C for 4-12 hours, preferably at 70°C for 8 hours.

[0070] As a more preferred embodiment of the preparation method of the fluorescent polymer of the present invention, the initiation conditions are: oxygen-free, oxygen content <100ppm, and polymerization time of 8-12h, preferably 10h.

[0071] In a preferred embodiment of the preparation method of the fluorescent polymer of the present invention, in step A2, the solvent exchange liquid includes ultrapure water, ethylenediaminetetraacetic acid, ethylenediaminetetramethylenephosphonic acid, citric acid, etc., preferably ultrapure water.

[0072] In a preferred embodiment of the preparation method of the fluorescent polymer of the present invention, in step A2, the polymer solution of step A1 is transferred to a solvent exchange solution and soaked three times to remove excess organic solvent from the polymer; the soaking time for each soaking is 2-12 hours, preferably 4 hours.

[0073] It should be noted that the fluorescent polymer described in this invention may be in a gel state.

[0074] In a preferred embodiment of the fluorescent polymer of the present invention, the thickness of the fluorescent polymer is 0.5-3 mm, preferably 1 mm or 1.5 mm.

[0075] The present invention also provides the application of the fluorescent polymer in the detection and early warning of local corrosion on printed circuit boards.

[0076] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0077] This invention prepares a fluorescent monomer by linking an aggregation-induced luminescence-containing tetraphenylethylene group to a specific polymer backbone. The fluorescent polymer obtained by reacting the fluorescent monomer with a specific polymerization monomer can be used to detect copper ions, and the detection has high sensitivity, good repeatability, and can be visually observed. Attached Figure Description

[0078] Figure 1 This is a flowchart illustrating the preparation process of the fluorescent monomer according to one embodiment of the present invention;

[0079] Figure 2 The fluorescence emission spectrum of the fluorescent monomer described in one embodiment of the present invention in a mixed solution of N,N-dimethylformamide / water is shown.

[0080] Figure 3 The fluorescence emission intensity of the fluorescent monomer in a mixed solution of N,N-dimethylformamide / water varies with the water content in the mixed solution, according to one embodiment of the present invention.

[0081] Figure 4 The fluorescence excitation-emission spectrum of the fluorescent monomer described in one embodiment of the present invention;

[0082] Figure 5 The fluorescence emission spectrum of the fluorescent monomer described in one embodiment of the present invention after being mixed with different metal ion solutions in a mixed solution of N,N-dimethylformamide / water.

[0083] Figure 6 The variation in fluorescence emission intensity of the fluorescent monomer described in one embodiment of the present invention after being mixed with different metal ion solutions in a mixed solution of N,N-dimethylformamide / water;

[0084] Figure 7 The fluorescence emission spectrum of the fluorescent monomer described in one embodiment of the present invention after being mixed with copper sulfate solutions of different concentrations in a mixed solution of N,N-dimethylformamide / water.

[0085] Figure 8 This is a variation of the UV-Vis absorption spectrum of a fluorescent monomer-copper sulfate mixed solution under different molar ratios in one embodiment of the present invention;

[0086] Figure 9 This is the total reflectance infrared spectrum of the fluorescent polymer and blank hydrogel according to one embodiment of the present invention;

[0087] Figure 10 This is an image of the fluorescent monomer, fluorescent polymer, and blank hydrogel described in one embodiment of the present invention under natural light;

[0088] Figure 11 The fluorescence excitation-emission spectrum of the fluorescent polymer described in one embodiment of the present invention;

[0089] Figure 12 This is the fluorescence emission spectrum of the fluorescent polymer described in one embodiment of the present invention after being mixed with copper sulfate solutions of different concentrations;

[0090] Figure 13 The image shows the fluorescent polymer, after being mixed with copper sulfate solutions of different concentrations according to one embodiment of the present invention, under natural light.

[0091] Figure 14 This is a comparison of the fluorescence emission spectra and concentration relationships of the fluorescent monomers and fluorescent polymers described in one embodiment of the present invention after being mixed with copper sulfate solutions of different concentrations;

[0092] Figure 15 This is a fluorescence lifetime fitting diagram of the fluorescent polymer described in one embodiment of the present invention;

[0093] Figure 16 The mechanical property test results of the fluorescent polymer described in one embodiment of the present invention;

[0094] Figure 17 The mechanical property test results of the fluorescent polymer described in one embodiment of the present invention;

[0095] Figure 18This is a schematic diagram of the regeneration curve of the fluorescent polymer after contact with divalent copper ions and the interaction with the chelating agent in one embodiment of the present invention;

[0096] Figure 19 for Figure 18 A schematic diagram illustrating the regeneration principle of the fluorescent polymer reacting with a chelating agent after contact with divalent copper ions.

[0097] Figure 20 This is an image showing the effect of in-situ detection of localized corrosion in printed circuit boards using the fluorescent polymer described in this invention.

[0098] Figure 21 This is the 1H NMR spectrum of the fluorescent monomer described in one embodiment of the present invention;

[0099] Figure 22 This is a mass spectrum of the fluorescent monomer described in one embodiment of the present invention;

[0100] Figure 23 This is a flowchart illustrating the preparation process of the fluorescent monomer according to one embodiment of the present invention;

[0101] Figure 24 This is a flowchart illustrating the preparation process of the fluorescent monomer according to one embodiment of the present invention;

[0102] Figure 25 This is a flowchart illustrating the preparation process of the fluorescent monomer according to one embodiment of the present invention;

[0103] Figure 26 This is a flowchart illustrating the preparation process of the fluorescent monomer according to one embodiment of the present invention. Detailed Implementation

[0104] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0105] Unless otherwise specified, the reagents, methods and equipment used in this invention are all conventional reagents, methods and equipment in this technical field.

[0106] Example 1

[0107] The structure of the tetraphenylethylene-based fluorescent monomer described in Example 1 of this invention is shown in the following formula:

[0108]

[0109] The preparation flowchart of the tetraphenylethylene-based fluorescent monomer (TPEBPy) described in this embodiment is as follows: Figure 1 As shown, the preparation method includes the following steps:

[0110] S1. 20g of 4-hydroxybenzophenone, 12g of 4,4'-dibromobenzophenone, 36g of Zn, 3mL of TiCl4 and 300mL of THF were added to a 500mL flask, and nitrogen gas was introduced to carry out the reaction. After the reaction was completed, the product was extracted three times with 100mL of dichloromethane. The crude product obtained by extraction was purified by silica gel column chromatography (the packed phase was petroleum ether:dichloromethane = 3:1, v / v) to obtain 7.6g of white powder, which is product 1.

[0111] S2. Take 5g of product 1 from step S1, and add it to a 250ml Erlenmeyer flask along with 3.2g of 3-vinylpyridine, 0.2g of Pd(OAc)2, 3ml of Et3N, 4.5g of K3PO4, and 40ml of DMF. Purge with nitrogen to carry out the reaction. After the reaction is complete, extract with 100mL of dichloromethane 6 times. The crude product obtained by extraction is purified by silica gel column chromatography (packed phase: petroleum ether: dichloromethane = 1:1, v / v) to obtain 2.4g of yellow powder, which is product 2.

[0112] S3. Take 2.4g of product 2 from step S2, 2.2g of 11-bromoundec-1-ene, 1.1g of K2CO3, and 300mL of acetone and add them to a 500mL flask for reaction. After the reaction is complete, extract three times with 100mL of dichloromethane. The crude product obtained from the extraction is purified by silica gel column chromatography (packed phase: petroleum ether:dichloromethane = 4:1, v / v) to obtain 1.2g of the tetraphenylethylene-based fluorescent monomer. The 1H NMR spectrum and mass spectrum of the fluorescent monomer are shown below. Figure 21 , 22 As shown.

[0113] The structure of the fluorescent polymer described in this embodiment is shown in the following formula:

[0114]

[0115] The preparation method of the fluorescent polymer (p(HEMA-co-AAc-TPEBPy)) described in this embodiment includes the following steps:

[0116] A1. 0.0254 g of the fluorescent monomer prepared in this example was mixed with 3.9042 g of ethyl methacrylate, 0.4324 g of acrylic acid, 0.015 g of N,N-methylenebisacrylamide, and 0.0623 g of polyethylene glycol diacrylate in N,N-dimethylformamide and the volume was adjusted to 15 mL. The solution was then placed in an oxygen-free environment, and 360 μL of tetramethylethylenediamine and 540 μL of potassium persulfate were added to carry out a free radical copolymerization reaction. After reacting for 10 h, a hydrogel-like fluorescent polymer solution with a thickness of 1 mm was obtained.

[0117] A2. The polymer solution described in step A1 is transferred to ultrapure water and soaked for 4 hours, and then washed 3 times. After completion, a hydrogel-like fluorescent polymer with a thickness of 0.7 mm is obtained.

[0118] The process flow of the fluorescent polymer described in this embodiment is shown in the following formula:

[0119]

[0120] Example 2

[0121] The structure and preparation method of the tetraphenylethylene-based fluorescent monomer described in this embodiment are the same as those in Example 1. The only difference between the preparation method of the fluorescent polymer described in this embodiment and that in Example 1 is that in step A1, the monomer used in the polymerization reaction is 4.3366 g of ethyl methacrylate. All other steps are the same as in Example 1.

[0122] The structure of the fluorescent polymer described in this embodiment is shown in the following formula:

[0123]

[0124] Example 3

[0125] The structure and preparation method of the tetraphenylethylene-based fluorescent monomer described in this embodiment are the same as those in Example 1. The only difference between the preparation method of the fluorescent polymer described in this embodiment and that in Example 1 is that in step A1, the monomer used in the polymerization reaction is a fluorescent monomer with a mass of 0.106 g. All other aspects are the same as in Example 1.

[0126] Example 4

[0127] The preparation method of the tetraphenylethylene-based fluorescent monomer described in this embodiment differs from that in Example 1 only in that 4-hydroxybenzophenone is replaced with benzophenone in step S3, and step S3 is not included in this embodiment. All other steps are the same as in Example 1. The flowchart for the preparation of the tetraphenylethylene-based fluorescent monomer in this embodiment is shown below. Figure 23 As shown, the structure of the fluorescent monomer is as follows:

[0128]

[0129] Example 5

[0130] The preparation method of the tetraphenylethylene-based fluorescent monomer described in this embodiment differs from that in Example 1 only in that, in step S1, 11-bromoundec-1-ene is replaced with acryloyl chloride; all other steps are the same as in Example 1. The flowchart for the preparation of the tetraphenylethylene-based fluorescent monomer in this embodiment is shown below. Figure 24 As shown, the structure of the fluorescent monomer is as follows:

[0131]

[0132] Example 6

[0133] The preparation method of the tetraphenylethylene-based fluorescent monomer described in this embodiment differs from that in Example 1 only in that, in step S1, 11-bromoundec-1-ene is replaced with bromobutane; all other steps are the same as in Example 1. The flowchart for the preparation of the tetraphenylethylene-based fluorescent monomer in this embodiment is shown below. Figure 25 As shown, the structure of the fluorescent monomer is as follows:

[0134]

[0135] Example 7

[0136] The preparation method of the tetraphenylethylene-based fluorescent monomer described in this embodiment differs from that in Example 1 only in that, in step S1, 11-bromoundec-1-ene is replaced with 1,4-bis(1H-1,2,4-triazol-1-yl)methyl)benzene; all other steps are the same as in Example 1. The flowchart for the preparation of the tetraphenylethylene-based fluorescent monomer in this embodiment is shown below. Figure 26 As shown, the structure of the fluorescent monomer is as follows:

[0137]

[0138] Experimental Example 1

[0139] 1. Fluorescence emission spectroscopy test

[0140] The fluorescent monomer described in Example 1 of this invention was dissolved in mixed solutions of N,N-dimethylformamide / water with different water contents. The fluorescence emission spectra of the fluorescent monomer are as follows: Figure 2 As shown; by Figure 2 It is known that when the water content in the N,N-dimethylformamide / water mixed solution exceeds 30%, the mixed solution can emit fluorescence; when the water content is less than 30%, the mixed solution hardly emits fluorescence; indicating that the fluorescent monomer prepared in Example 1 of the present invention has aggregation-induced emission effect.

[0141] Figure 3 This is a graph showing the change in fluorescence emission intensity of the fluorescent monomer described in Example 1 of the present invention with the water content in a mixed solution of N,N-dimethylformamide / water; Figure 3 It is known that the fluorescence emission intensity of the fluorescent monomer described in this invention reaches its maximum when the water content is 60%, and then gradually decreases.

[0142] Figure 4 The fluorescence excitation-emission spectrum of the fluorescent monomer described in Example 1 of this invention; from Figure 4It is known that the maximum excitation wavelength of the fluorescent monomer described in this invention is 415 nm, indicating that the fluorescent monomer prepared in Example 1 of this invention has the characteristic of being excited by visible light.

[0143] Experimental Example 2

[0144] 1. Tests on the quenching effect of different metal ions on the fluorescent monomer described in this invention

[0145] The fluorescent monomer described in Example 1 of this invention was dissolved in a 70% N,N-dimethylformamide / water mixed solution, followed by a 10% concentration... -5 Different metal chloride solutions of M were added dropwise to the above solution, and the fluorescence emission spectra of the fluorescent monomer mixed with different metal ions were as follows: Figure 5 , 6 As shown; from Figure 5 , 6 It is known that monovalent copper ions and divalent copper ions have a very obvious fluorescence quenching effect on the fluorescent monomer; that is, monovalent copper ions and divalent copper ions can be used as quenchers for the fluorescent monomer prepared in Example 1 of this invention.

[0146] 2. Quenching test of the fluorescent monomer described in this invention by different concentrations of divalent copper ions

[0147] The fluorescent monomer described in Example 1 of this invention was dissolved in a 70% N,N-dimethylformamide / water mixed solution, followed by a 10% concentration... -3 -10 -5 Copper sulfate solution M was added dropwise to the above solutions respectively, and the fluorescence emission spectra of the fluorescent monomer mixed with copper sulfate solutions of different concentrations are as follows: Figure 7 As shown; from Figure 7 It is known that divalent copper ions have a quenching effect on the fluorescent monomer prepared in Example 1 of this invention, and the detection limit of divalent copper ions is 10. -5 M.

[0148] 3. UV-Vis absorption spectroscopy of fluorescent monomers and divalent copper ions at different molar ratios

[0149] The fluorescent monomer described in Example 1 of this invention was mixed with a copper sulfate solution, wherein the molar ratio of the fluorescent monomer to divalent copper ions was 1:0.1-4. The absorbance of the mixed solution was measured using a UV-Vis spectrophotometer, and the test results are as follows. Figure 8 As shown; from Figure 8 It can be seen that when the ratio of fluorescent monomer to divalent copper ion is 1:2, the absorbance of the mixed solution no longer decreases; indicating that the molar ratio of fluorescent monomer to divalent copper ion prepared in Example 1 of this invention is 1:2, that is, one pyridine group in the fluorescent monomer can combine with one divalent copper ion.

[0150] Test Example 3

[0151] The hydrogel-like fluorescent polymer (fluorescent hydrogel) described in Example 1 of this invention and a blank control hydrogel without the fluorescent monomer described in this invention were subjected to total reflectance infrared spectroscopy tests. The results are as follows: Figure 9 As shown; and the fluorescent monomer, fluorescent hydrogel, and blank control hydrogel described in Example 1 of this invention were photographed under natural light, as shown in the images. Figure 10 As shown; by Figure 9 , 10 It can be seen that the present invention has successfully prepared fluorescent polymers.

[0152] Figure 11 The fluorescence excitation-emission spectrum of the fluorescent polymer described in Example 1 of this invention; from Figure 11 It is known that the maximum excitation wavelength of the fluorescent polymer described in this invention is 427 nm; indicating that the fluorescent polymer prepared in this invention has the characteristic of being excited by visible light.

[0153] Test Example 4

[0154] 1. Quenching test of the fluorescent polymer described in this invention by different concentrations of divalent copper ions

[0155] The fluorescent polymer described in Example 1 of this invention was immersed in a solution with a concentration of 10... -2 -10 -5 In a copper sulfate solution of M; the fluorescence emission spectra of the fluorescent polymer mixed with copper sulfate solutions of different concentrations are as follows: Figure 12 As shown, photographs of the fluorescent polymer mixed with copper sulfate solutions of different concentrations under natural light are shown below. Figure 13 As shown; from Figure 12 It can be seen that divalent copper ions have a very obvious quenching effect on the fluorescent polymer prepared in Example 1 of this invention. Figure 13 As can be seen, the present invention allows direct visual observation of the color change of the fluorescent polymer, which is a change from yellow to green; Figure 14 This is a comparison of the fluorescence emission spectra of the fluorescent monomers and fluorescent polymers described in Example 1 of the present invention after mixing with copper sulfate solutions of different concentrations, and the results are based on the concentrations of the solutions. Figure 14 It can be seen that the quenching degree of the fluorescent polymer is linearly related to the concentration of divalent copper ions, that is, the higher the concentration of divalent copper ions, the more obvious the quenching degree; indicating that divalent copper ions have a quenching effect on the fluorescent polymer prepared in Example 1 of this invention, and the detection limit for divalent copper ions is 10. -4 M.

[0156] Test Example 5

[0157] In this test example, the average lifetime obtained from the fluorescence lifetime fitting results of fluorescent monomers in solid and liquid states was fixed as the τ1 and τ2 values ​​of the fluorescent polymer, respectively. The fitting was performed on the software to obtain the distribution ratio of the fluorescent monomers of the present invention in different states in the fluorescent gel. The results are shown in Table 1 below. The fitting degree reached 0.999, thus the distribution ratio of the aggregated state and the dispersed state of the fluorescent monomers in the fluorescent polymer prepared in Example 1 of the present invention was 85% and 15%, respectively. Figure 15 This is a fluorescence lifetime fitting diagram of the fluorescent polymer described in Example 1 of the present invention; τ ave =(A1τ1) 2 +A2τ2 2 ) / (A1τ1+A2τ2).

[0158] Table 1

[0159]

[0160] Test Example 6

[0161] The fluorescent polymer described in Example 1 of this invention was fabricated into a piece with a diameter of 13 mm and a thickness of 0.7 mm. This piece was then adhered to a compression rod, and a vertical pressure of 6 N was applied to the surface coating of bare copper or a circuit board for 60 seconds under air or underwater conditions. The mechanical property test results of the fluorescent polymer are as follows: Figure 16 , 17 As shown; from Figure 16 , 17 It can be seen that the adhesion force between the fluorescent polymer and the coating on the circuit board surface reaches 30 kPa, indicating that the fluorescent polymer or gel of the present invention can adhere to most metal and coating surfaces, and it still has good adhesion after ten peel tests.

[0162] Test Example 7: Repeatability Test

[0163] The fluorescent polymer described in Example 1 of this invention is immersed in 10... -3 The fluorescent polymer was immersed in M ​​copper sulfate solution for 6 hours to allow it to fully contact divalent copper ions and induce a quenching effect; then the quenched fluorescent polymer was immersed in 10... -2 After 6 hours in an oxalic acid solution containing M chelating agent, the copper ions are released from the pyridine groups in the fluorescent polymer or gel through a stronger complexation reaction between oxalic acid and divalent copper ions. Finally, the fluorescent polymer or gel is soaked in deionized water for 2 hours to remove any residual oxalic acid. Figure 18 , 19 The images show the regeneration curves and schematic diagrams illustrating the regeneration principle of the fluorescent polymer prepared in Example 1 of this invention after contact with divalent copper ions and its interaction with a chelating agent. Figure 18It can be seen that the regenerated fluorescent polymer still has a good recognition effect on divalent copper ions, and the effect remains the same even after ten cycles of regeneration test; indicating that the fluorescent polymer prepared in Example 1 of the present invention has good reusability.

[0164] Test Example 8

[0165] In this test example, a printed bare copper board was sprayed with anti-corrosion paint. Then, a scratch tester was used to damage the anti-corrosion coating on the bare copper surface to artificially create local defects. The fluorescent polymer described in this embodiment of the invention was then attached to the defect. The circuit board was placed in a salt spray chamber for a neutral salt spray test to accelerate the corrosion rate of the copper at the local defects. After 24 hours of salt spray testing, no obvious corrosion was observed by the naked eye at the local defects where the fluorescent polymer was not attached. However, the fluorescent polymer attached to the local defects underwent a visually observable color change, changing from yellow to green. Therefore, the degree of corrosion can be judged based on the color change of the fluorescent polymer. Figure 20 This is an image illustrating the effect of in-situ detection of localized corrosion in a printed circuit board using fluorescent polymers, according to an embodiment of the present invention. Figure 20 It is understood that the fluorescent polymer described in the embodiments of the present invention has in-situ corrosion early warning performance.

[0166] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A fluorescent monomer based on tetraphenylethylene, characterized in that, The structural formula of the fluorescent monomer is shown in formula (Ⅰ): Equation (I); The structure of R is given by equation (V): Formula (V); Where n has a value between 1 and 20.

2. The tetraphenylethylene-based fluorescent monomer according to claim 1, characterized in that, The value of n is 10.

3. The method for preparing tetraphenylethylene-based fluorescent monomers according to claim 1 or 2, characterized in that, The method includes the following steps: S1. A solution of 4-hydroxybenzophenone, a solution of 4,4'-dibromobenzophenone, and a catalyst were reacted under nitrogen atmosphere, followed by purification by silica gel column chromatography to obtain product 1. S2. The product 1 obtained in step S1 is reacted with 3-vinylpyridine and a catalyst in nitrogen, and then purified by silica gel chromatography to obtain product 2. S3. The product 2 obtained in step S2 is reacted with the brominated raw material and the catalyst in nitrogen atmosphere, followed by purification by silica gel column chromatography to obtain the tetraphenylethylene-based fluorescent monomer; the brominated raw material is of formula (XII): Formula (XII); Where n has a value between 1 and 20.

4. The method for preparing a tetraphenylethylene-based fluorescent monomer according to claim 3, characterized in that, The brominated raw material is 11-bromoundec-1-ene.

5. A fluorescent polymer, characterized in that, The fluorescent polymer is obtained by using the fluorescent monomer as described in claim 1 or 2, and the preparation method of the fluorescent polymer includes the following steps: A1. The fluorescent monomer as described in claim 1 or 2 is mixed with the polymerization monomer, initiator, and crosslinking agent in an organic solvent and subjected to a free radical copolymerization reaction to obtain a polymer solution. A2. The polymer solution described in step A1 is transferred to a solvent exchange solution for immersion. After solvent exchange is completed, a fluorescent polymer is obtained. The polymerization monomer is a combination of formula (XV) and formula (XVI): Formula (XV); Formula (XVI).

6. The application of the fluorescent polymer according to claim 5 in the detection and early warning of localized corrosion on printed circuit boards.

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