1,2,3-trichlorobenzene detection and analysis material and preparation method thereof

Abstract

The application belongs to the field of environmental analysis and detection materials, and provides a 1,2,3-trichlorobenzene detection and analysis material and a preparation method thereof, wherein a composite extraction and recognition coating is constructed by forming a Si-O-Si network layer on the surface of a substrate and fixing core-shell composite particles, the core-shell composite particles are composed of a covalent organic framework core connected by a beta-ketoenamine bond and a molecularly imprinted polymer shell, and the molecularly imprinted polymer shell takes 1,2,3-trichlorobenzene as a template molecule and takes 4-vinylpyridine as a functional monomer. The number average particle size of the material is 80-250 nm, the shell thickness is 5-30 nm, the composite extraction and recognition coating thickness is 3-20 microns, and the substrate is a 304 stainless steel wire, a titanium wire, a quartz fiber or a glass fiber. The pain points of the core-shell composite particles in the substrate surface fixation, the controllable coating thickness and the difficult control of the residual after elution are solved, and the material has practical application value for 1,2,3-trichlorobenzene detection and analysis.

Description

Technical Field

[0001] This invention relates to the field of materials chemistry, specifically to a 1,2,3-trichlorobenzene detection and analysis material and its preparation method. Background Technology

[0002] The detection and analysis of 1,2,3-trichlorobenzene typically relies on the formation of a composite extraction recognition coating on a substrate surface. This coating allows for sufficient contact between the 1,2,3-trichlorobenzene in the sample and its release during the elution step, facilitating subsequent quantitative determination by gas chromatography. Since the substrate can be made of 304 stainless steel wire, titanium wire, quartz fiber, or glass fiber, the coating requires washing with ethanol and deionized water, elution with methanol and glacial acetic acid, and vacuum drying, aging, or activation treatments during preparation and use. Therefore, specific requirements are placed on the anchoring effect of the anchoring layer, the controllability of the composite extraction recognition coating thickness, and the structural stability of the core-shell composite particles. Simultaneously, after the molecularly imprinted polymer shell is formed with template molecules, functional monomers, crosslinking agents, and initiators, its elution endpoint criteria and the residual 1,2,3-trichlorobenzene content directly affect the repeatability and reliability of the detection and analysis. Developing preparable and reproducible detection and analysis materials to meet these requirements is a direction of ongoing interest in this field and has significant potential for widespread application.

[0003] For example, Chinese patent CN113385154A discloses a molecularly imprinted sol-gel coated fiber tube solid-phase microextraction device and its preparation method. However, it focuses more on the molecularly imprinted polymer coating body and involves less attention to the structural design of fixing between the substrate surface and the core-shell composite particles through the anchoring layer. This leads to unstable fixation under repeated washing, vacuum drying and aging conditions, which affects the consistency of the coating thickness for composite extraction identification. For example, Chinese patent CN115093525A discloses a multifunctional monomer covalent organic framework molecularly imprinted polymer and its preparation method and application. However, through the electrostatic interaction, π-π interaction, hydrogen bonding and chelation of various functional monomers with different parts of the template molecule C3G, there is still room for optimization in the control of residues after elution and the repeatability of preparation. Summary of the Invention

[0004] The purpose of this invention is to provide a 1,2,3-trichlorobenzene detection and analysis material and its preparation method, which solves the current pain points of core-shell composite particles being difficult to fix on the substrate surface, control the coating thickness, and control the residue after elution.

[0005] This invention establishes a stable connection between core-shell composite particles and the substrate through a Si-O-Si network layer of the anchoring layer. At the same time, it utilizes a covalent organic framework core connected by β-keto-enamine bonds to provide structural support and controllable number-average particle size. Furthermore, a molecularly imprinted polymer shell is formed in situ on the surface of the vinylized core to achieve both fixation, composite extraction recognition, and residue control after elution.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A 1,2,3-trichlorobenzene detection and analysis material includes a substrate and a composite extraction and recognition coating formed on the surface of the substrate, the composite extraction and recognition coating comprising:

[0008] a. A β-ketoenamine-linked covalent organic framework core, wherein the β-ketoenamine-linked covalent organic framework core is prepared by reacting 2,4,6-tricarboxymethylphloroglucinol with p-phenylenediamine;

[0009] b. A molecularly imprinted polymer shell coating the surface of the β-ketoenamine-linked covalent organic framework core, wherein the β-ketoenamine-linked covalent organic framework core is vinylized with 3-(methacryloyloxy)propyltrimethoxysilane to obtain a vinylized core, and the molecularly imprinted polymer shell is formed by polymerization on the surface of the vinylized core using 1,2,3-trichlorobenzene as a template molecule, 4-vinylpyridine as a functional monomer, ethylene glycol dimethacrylate as a crosslinking agent, and 2,2-azobisisobutyronitrile as an initiator, followed by elution. The vinylized core and the molecularly imprinted polymer shell constitute a core-shell composite particle.

[0010] c. An anchoring layer located between the substrate surface and the core-shell composite particles, wherein the anchoring layer is a Si-O-Si network layer formed by the condensation of 3-aminopropyltriethoxysilane and tetraethoxysilane, used to fix the core-shell composite particles to the substrate surface;

[0011] The number-average particle size of the covalent organic framework core linked by the β-keto-enamine bond is 80-250 nm, the thickness of the molecularly imprinted polymer shell is 5-30 nm, the thickness of the composite extraction recognition coating is 3-20 μm, and the substrate is one of 304 stainless steel wire, titanium wire, quartz fiber, or glass fiber.

[0012] Furthermore, the β-ketoenamine bonded covalent organic framework core is prepared by the following steps:

[0013] A1. 2,4,6-tricarboxymethyl phloroglucinol and p-phenylenediamine are added to a mixed solvent composed of 1,4-dioxane, 1,3,5-trimethylbenzene and glacial acetic acid at a molar ratio of 1:1-1.5, wherein the volume ratio of 1,4-dioxane, 1,3,5-trimethylbenzene and glacial acetic acid is 4-8:4-8:0.5-2;

[0014] A2. Transfer to a sealed reactor under nitrogen protection and react at 110-130℃ for 24-72 hours;

[0015] A3. Wash with ethanol 2-4 times, then with methanol 2-4 times, and vacuum dry at 60-80℃ for 8-16 hours;

[0016] A4. Obtain the covalent organic framework core body with β-keto-enamine bond linkage, and its number average particle size is 80-250 nm.

[0017] Furthermore, the vinylized nucleus is prepared by the following steps:

[0018] B1. The β-keto-enamine bonded covalent organic framework core is dispersed in a mixture of ethanol and deionized water, wherein the volume ratio of ethanol to deionized water is 5-20:1, and the pH is adjusted to 4.5-5.5 with glacial acetic acid.

[0019] B2. Add 3-(methacryloyloxy)propyltrimethoxysilane to the covalent organic framework core linked by the β-ketoenamine bond at a mass ratio of 100:5-20, and react at 50-75°C for 2-8 hours.

[0020] B3. After the reaction, wash with ethanol 2-4 times and dry under vacuum at 50-70℃ for 4-12 hours;

[0021] B4. The vinyl nucleus is obtained, wherein the grafting amount of 3-(methacryloyloxy)propyltrimethoxysilane is 0.20-0.80 mmol / g.

[0022] Furthermore, the molecularly imprinted polymer shell is prepared through the following steps:

[0023] C1. Add 1,2,3-trichlorobenzene and 4-vinylpyridine to acetonitrile at a molar ratio of 1:2-6 and pre-complex at 20-40℃ for 2-8 hours;

[0024] C2. Add the vinylized nucleus, ethylene glycol dimethacrylate, and 2,2-azobisisobutyronitrile to the system obtained in step C1, wherein the molar ratio of 1,2,3-trichlorobenzene, 4-vinylpyridine, ethylene glycol dimethacrylate, and 2,2-azobisisobutyronitrile is 1:2-6:8-20:0.05-0.20;

[0025] C3. After purging with nitrogen for 10-30 minutes, polymerize at 55-70℃ for 8-24 hours under nitrogen protection;

[0026] C4. Elute 3-8 times with an eluent containing methanol and glacial acetic acid in a volume ratio of 9-12:1, and dry at 40-60℃ for 4-10 hours;

[0027] C5. Obtain the core-shell composite particles with a shell thickness of 5-30 nm.

[0028] Furthermore, the anchoring layer and the composite extraction recognition coating are formed through the following steps:

[0029] D1. Clean the 304 stainless steel wire, titanium wire, quartz fiber or glass fiber substrate with ethanol and deionized water in sequence and then dry it;

[0030] D2. Add 3-aminopropyltriethoxysilane and tetraethoxysilane to a hydrolysis system consisting of ethanol, deionized water and 25% ammonia, wherein the molar ratio of 3-aminopropyltriethoxysilane to tetraethoxysilane is 1:0.5-4, and the volume ratio of ethanol, deionized water and 25% ammonia is 20-60:1-10:0.1-2, and hydrolyze at 25-45℃ for 0.5-4h.

[0031] D3. Disperse the core-shell composite particles in the hydrolysis system obtained in step D2 at a concentration of 0.5-20 g / L, and coat them onto the substrate surface by dip coating or stretch coating.

[0032] D4. Curing at 70-120℃ for 0.5-2h yields the 1,2,3-trichlorobenzene detection and analysis material, the thickness of which is 3-20μm for the composite extraction identification coating.

[0033] Furthermore, the vinylized core accounts for 40-80 wt% of the total mass of the core-shell composite particles, the molecularly imprinted polymer shell accounts for 20-60 wt% of the total mass of the core-shell composite particles, and the sum of their mass fractions is 100 wt%. The thickness of the anchoring layer is 50-1000 nm. In the anchoring layer, 3-aminopropyltriethoxysilane and tetraethoxysilane form a Si-O-Si network structure. The Si-O-Si network structure is connected to the substrate surface through Si-O-Si or Si-O-metal covalent bonds. The anchoring layer fixes the core-shell composite particles through physical embedding of the siloxane network.

[0034] Furthermore, the diameter of the substrate is 50-300 μm, and the effective coating length of the composite extraction recognition coating on the substrate surface is 5-30 mm.

[0035] As a concept of this invention, the present invention adopts a structural design and preparation idea of ​​anchoring layer and core-shell composite particles working together, which is mainly used to enhance the fixation effect of composite extraction recognition coating on substrate surface and improve the repeatability of detection and analysis. Specifically, the anchoring layer is a Si-O-Si network layer formed by the hydrolysis and condensation of 3-aminopropyltriethoxysilane and tetraethoxysilane. This provides an interface on the substrate surface that can be covalently bonded to Si-O-Si or Si-O-metals. At the same time, it physically embeds the core-shell composite particles in a siloxane network, thereby reducing the risk of coating peeling during the coating process and subsequent vacuum drying, aging, or activation. The covalent organic framework core with β-ketoenamine bonds has a controllable number-average particle size and can be vinylated with 3-(methacryloyloxy)propyltrimethoxysilane. This facilitates in-situ polymerization on its surface to form a molecularly imprinted polymer shell. This allows the core-shell composite particles to acquire recognition characteristics for 1,2,3-trichlorobenzene while maintaining structural support. Furthermore, by controlling the shell thickness and elution conditions, both the recognition function and the residual 1,2,3-trichlorobenzene content after elution can be controlled.

[0036] This invention also discloses a method for preparing a 1,2,3-trichlorobenzene detection and analysis material, comprising the following steps:

[0037] S1. 2,4,6-tricarboxymethylphloroglucinol and p-phenylenediamine were reacted under nitrogen protection in a mixed solvent consisting of 1,4-dioxane, 1,3,5-trimethylbenzene and glacial acetic acid to prepare a covalent organic framework core with β-keto-enamine bonds;

[0038] S2. The β-ketoenamine-linked covalent organic framework core is dispersed in a mixture of ethanol and deionized water and then vinylized with 3-(methacryloyloxy)propyltrimethoxysilane to prepare a vinylized core;

[0039] S3. 1,2,3-trichlorobenzene and 4-vinylpyridine are pre-complexed in acetonitrile. The vinylized core, ethylene glycol dimethacrylate and 2,2-azobisisobutyronitrile are added to the resulting system. Molecular imprinting polymerization is carried out under nitrogen protection, and the particles are eluted and dried to prepare core-shell composite particles.

[0040] S4. The substrate is washed and dried sequentially with ethanol and deionized water; 3-aminopropyltriethoxysilane and tetraethoxysilane are added to a hydrolysis system composed of ethanol, deionized water and ammonia in a volume ratio of 20-60:1-10:0.1-2 at a molar ratio of 1:0.5-4, and hydrolyzed and condensed at 25-45℃ for 0.5-4h; the core-shell composite particles are dispersed in the obtained hydrolysis system at 0.5-20g / L, and coated onto the substrate surface by dip coating or stretch coating to form an anchoring layer, thereby fixing the core-shell composite particles to the substrate surface;

[0041] S5. Curing at 70-120℃ for 0.5-2h yields the 1,2,3-trichlorobenzene detection and analysis material.

[0042] Further, in step S1, the molar ratio of 2,4,6-tricarboxymethyl phloroglucinol to p-phenylenediamine is 1:1-1.5, the volume ratio of 1,4-dioxane, 1,3,5-trimethylbenzene and glacial acetic acid is 4-8:4-8:0.5-2, the reaction temperature is 110-130℃, and the reaction time is 24-72h;

[0043] In step S2, the pH of the system is adjusted to 4.5-5.5 with glacial acetic acid, the reaction temperature is 50-75℃, the reaction time is 2-8h, and the grafting amount of 3-(methacryloyloxy)propyltrimethoxysilane is 0.20-0.80mmol / g.

[0044] In step S3, the molar ratio of 1,2,3-trichlorobenzene, 4-vinylpyridine, ethylene glycol dimethacrylate and 2,2-azobisisobutyronitrile is 1:2-6:8-20:0.05-0.20, the polymerization temperature is 55-70℃, the polymerization time is 8-24h, and the eluent is used to elute 3-8 times with a methanol and glacial acetic acid volume ratio of 9-12:1.

[0045] In step S4, the molar ratio of 3-aminopropyltriethoxysilane to tetraethoxysilane is 1:0.5-4, the volume ratio of ethanol, deionized water and 25% ammonia is 20-60:1-10:0.1-2, the hydrolysis temperature is 25-45℃, the hydrolysis time is 0.5-4h, and the core-shell composite particles are fixed on the substrate surface by dip coating or stretch coating, with 1-10 coating times.

[0046] In step S5, the curing temperature is 70-120℃ and the curing time is 0.5-2h.

[0047] Further, the substrate is one of 304 stainless steel wire, titanium wire, quartz fiber or glass fiber, and its diameter is 50-300 μm. The effective coating length on the substrate surface is 5-30 mm. The number average particle size of the covalent organic framework core with β-keto-enamine bond obtained in step S1 is 80-250 nm. The shell thickness of the core-shell composite particles obtained in step S3 is 5-30 nm. The content of 1,2,3-trichlorobenzene remaining in the core-shell composite particles after template elution in step S3 is quantitatively determined by gas chromatography using the external standard method. The calculation basis is the total dry weight of the core-shell composite particles after elution, and its value is not higher than 0.5 wt%. The thickness of the composite extraction identification coating of the 1,2,3-trichlorobenzene detection and analysis material obtained in step S5 is 3-20 μm.

[0048] Furthermore, when synthesizing the covalent organic framework core linked by β-ketoenamine bonds, the absolute amount of 2,4,6-tricarboxymethylphloroglucinol used per batch was 0.500 g, the absolute amount of p-phenylenediamine used per batch was 0.309-0.342 g, and the total volume of the mixed solvent of 1,4-dioxane / 1,3,5-trimethylbenzene / glacial acetic acid was 11.0-15.5 mL.

[0049] Furthermore, in the vinylization step, the initial dispersion concentration of the covalent organic framework core linked by β-keto-enamine bonds in the mixture of ethanol and deionized water is 5.0 g / L, and the dispersion is performed by ultrasonic dispersion for 30 min.

[0050] Furthermore, the dip coating operation has a pull-up rate of 2 mm / s and a single immersion time of 10 s; the pull coating operation has a coating rate of 3 mm / s; and the drying temperature between two adjacent coatings is 25°C and the time is 10 min when coating multiple times.

[0051] Furthermore, the vacuum degree used in the vacuum drying step is -0.095 MPa.

[0052] Furthermore, the number-average particle size of the covalent organic framework core linked by the β-keto-enamine bond was determined by statistical analysis of transmission electron microscopy images; the thickness of the molecularly imprinted polymer shell, the thickness of the anchoring layer, and the thickness of the composite extraction recognition coating were all determined by cross-sectional transmission electron microscopy or cross-sectional scanning electron microscopy images.

[0053] Furthermore, the grafting amount of the 3-(methacryloyloxy)propyltrimethoxysilane was determined by the following method: the vinyl nucleus was extracted with ethanol by Soxhlet extraction for 30 min to remove the physically adsorbed components, and then vacuum dried at 60-80℃ until the mass was constant. The weight loss in the temperature range of 200-500℃ was determined by thermogravimetric analysis, and the grafting amount (mmol / g) was calculated based on the dry basis mass of the vinyl nucleus.

[0054] Furthermore, the 1,2,3-trichlorobenzene detection and analysis material is aged at 180-280℃ for 5-60 minutes before use, or activated in methanol at 40-64℃ in a sealed container for 5-30 minutes.

[0055] Furthermore, in the pre-complexation stage of the molecularly imprinted polymerization step, 1,2,3-trichlorobenzene and 4-vinylpyridine form a homogeneous solution without visible precipitate in acetonitrile.

[0056] Furthermore, the nitrogen purging process used to establish an inert atmosphere in the synthesis and polymerization steps was carried out three times (approximately 5 minutes each time), and a positive pressure inert atmosphere was maintained in the reaction system throughout the reaction using nitrogen balloons.

[0057] Furthermore, the amount of washing or eluting solution used in each washing and elution step, and the endpoint criteria for washing or elution are as follows: In each washing step, the amount of washing solution used is 20.0-30.0 mL, and the washing endpoint is defined as the absorbance of the washing solution at 254 nm being less than 0.01 as detected by a UV-Vis spectrophotometer; In each elution step, the amount of eluting solution used is 30.0 mL, and the elution endpoint is defined as the content of 1,2,3-trichlorobenzene in the eluting solution being less than 0.01 μg / mL as detected by the external standard method of gas chromatography.

[0058] As another concept of the present invention, the stepwise preparation and in-situ surface assembly process design is mainly used to enhance the repeatability of the preparation and coating process of core-shell composite particles and reduce batch differences. First, a covalent organic framework core with β-ketoenamine bonds was prepared by reacting 2,4,6-tricarboxymethyl phloroglucinol with p-phenylenediamine under nitrogen protection. This core was then reacted with 3-(methacryloyloxy)propyltrimethoxysilane in an ethanol and deionized water system with pH adjusted by glacial acetic acid to obtain a vinylized core, facilitating subsequent polymerization. Subsequently, 1,2,3-trichlorobenzene and 4-vinylpyridine were pre-complexed in acetonitrile, and molecularly imprinted polymerization was performed on the surface of the vinylized core. After elution and drying, a molecularly imprinted polymer shell was formed, ensuring template molecule removal and residue control. Finally, an anchoring layer was formed by the condensation of 3-aminopropyltriethoxysilane and tetraethoxysilane in a hydrolysis system. The core-shell composite particles were then fixed to the substrate surface by dip coating or stretch coating, and cured to obtain a composite extraction recognition coating, ensuring a one-to-one correspondence between the material preparation path and structural characteristics.

[0059] The covalent organic framework core, linked by β-keto-enamine bonds, primarily provides structural support and morphological constraint in the core-shell composite particles. Its controllable number-average particle size allows for more predictable packing states during coating and curing of the composite extraction recognition coating, and provides a reaction surface for the vinylation of 3-(methacryloyloxy)propyltrimethoxysilane. The molecularly imprinted polymer shell, using 1,2,3-trichlorobenzene as a template molecule, forms a specific recognition environment with functional monomers, crosslinking agents, and initiators, directly contributing to the extraction recognition ability of 1,2,3-trichlorobenzene. When the two work synergistically, the stable framework of the core reduces the risk of deformation of the shell during polymerization, elution, and vacuum drying, making it easier for the molecularly imprinted polymer shell to maintain the desired structure. The limited thickness and continuous outer surface of the shell facilitate the establishment of elution endpoint criteria and reduce fluctuations in residual 1,2,3-trichlorobenzene content, thus achieving a more stable balance between extraction recognition and post-elution residue control.

[0060] Beneficial technical effects

[0061] 1. An anchoring layer, a Si-O-Si network layer, is formed by the hydrolytic condensation of 3-aminopropyltriethoxysilane and tetraethoxysilane, which enables the core-shell composite particles to be stably fixed on the substrate surface and maintain the integrity of the coating after cleaning with ethanol and deionized water, vacuum drying, aging or activation.

[0062] 2. The covalent organic framework core linked by β-keto-enamine bonds has a controllable number-average particle size. Vinylation with 3-(methacryloyloxy)propyltrimethoxysilane yields a vinylized core, which facilitates in-situ polymerization on its surface and the formation of a uniform molecularly imprinted polymer shell, thereby improving the structural reproducibility of the core-shell composite particles.

[0063] 3. The molecularly imprinted polymer shell uses 1,2,3-trichlorobenzene as a template molecule and 4-vinylpyridine as a functional monomer. The template molecule is removed through an elution step, and the content of residual 1,2,3-trichlorobenzene is used as a quality constraint, which helps to reduce the detection and analysis bias caused by residues and improve the consistency of results.

[0064] 4. This detection and analysis material can be used with 304 stainless steel wire, titanium wire, quartz fiber or glass fiber as the substrate. The core-shell composite particles can be introduced into the anchoring layer by dip coating or stretch coating and then cured to form a composite extraction and identification coating, thus taking into account both the material structure transferability and process adaptability. Attached Figure Description

[0065] Figure 1 This is a superimposed diagram of the N2 adsorption-desorption isotherms.

[0066] Figure 2 This is a differential distribution curve of the BJH aperture distribution.

[0067] Figure 3 The cumulative distribution curve of the cumulative pore volume of BJH is shown.

[0068] Figure 4 This is a mean plus standard deviation band plot for EF-time dynamics.

[0069] Figure 5 This is a TGA quality-temperature overlay.

[0070] Figure 6 This is a superimposed graph of DTG mass change rate versus temperature.

[0071] Figure 7 This is a superimposed image of the narrow-area Si2p spectrum in XPS.

[0072] Figure 8 This is a superimposed image of the N1s narrow spectrum of XPS.

[0073] Figure 9 This is a macroscopic optical photograph of the β-ketoenamine bonded covalent organic framework core prepared in Example 1.

[0074] Figure 10 This is a macroscopic optical photograph of the core-shell composite particles prepared in Example 1.

[0075] Figure 11 This is a macroscopic optical photograph of the 1,2,3-trichlorobenzene detection and analysis material prepared in Example 1.

[0076] Figure 12 This is a low-magnification scanning electron microscope image of the β-ketoenamine bonded covalent organic framework core prepared in Example 1.

[0077] Figure 13 This is a low-magnification transmission electron microscope bright-field image of the β-ketoenamine bonded covalent organic framework core prepared in Example 1. Detailed Implementation

[0078] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0079] Example 1

[0080] (1) Preparation of covalent organic framework cores linked by β-keto-enamine bonds

[0081] Weigh 0.500 g (2.38 mmol) of 2,4,6-tricarboxymethyl phloroglucinol and 0.322 g (2.98 mmol) of p-phenylenediamine, with a molar ratio of 1:1.25. Add them to a mixed solvent (volume ratio 6:6:1, total volume 13.0 mL) consisting of 6.0 mL of 1,4-dioxane, 6.0 mL of 1,3,5-trimethylbenzene, and 1.0 mL of glacial acetic acid. Sonicate for 5 min to ensure homogeneity. Purge the system with nitrogen three times (approximately 5 min each time), maintaining a positive pressure inert atmosphere throughout the process using a nitrogen balloon. Transfer the mixture to a sealed reactor and react at 120 °C for 48 h. After the reaction was completed and cooled to room temperature, the solution was first washed three times with ethanol (20.0 mL each time, with the endpoint determined by the absorbance of the washing solution at 254 nm being less than 0.01 using a UV-Vis spectrophotometer), and then washed three times with methanol (20.0 mL each time, with the endpoint determined by the same criteria). The solution was then vacuum dried at 70 °C and a vacuum degree of -0.095 MPa for 12 h to obtain a covalent organic framework core with β-keto-enamine bonds and a number average particle size of 165 nm. The number average particle size was determined by statistical analysis of transmission electron microscopy images.

[0082] (2) Preparation of vinyl nuclei

[0083] The β-ketoenamine-linked covalent organic framework core of this embodiment was dispersed at an initial concentration of 5.0 g / L in a mixture of 92.3 mL of ethanol and 7.7 mL of deionized water (volume ratio 12:1, total volume 100.0 mL), and ultrasonically dispersed for 30 min. The pH was adjusted to 5.0 with glacial acetic acid. 3-(methacryloyloxy)propyltrimethoxysilane was added to the β-ketoenamine-linked covalent organic framework core of this embodiment at a mass ratio of 100:12, and the reaction was carried out at 62 °C for 5 h. After the reaction, the core was washed three times with ethanol (30.0 mL each time), and then vacuum dried at 60 °C and a vacuum degree of -0.095 MPa for 8 h to obtain the vinylized core of this embodiment. The vinylized nucleus of this embodiment was extracted with ethanol by Soxhlet extraction for 30 min to remove physically adsorbed components. After being vacuum dried at 70°C until the mass was constant, the weight loss in the temperature range of 200–500°C was determined by thermogravimetric analysis. The grafting amount of 3-(methacryloyloxy)propyltrimethoxysilane was calculated to be 0.50 mmol / g based on the dry basis mass of the vinylized nucleus.

[0084] (3) Preparation of core-shell composite particles

[0085] 0.181 g (1.00 mmol) of 1,2,3-trichlorobenzene and 0.421 g (4.00 mmol) of 4-vinylpyridine were added to 10.0 mL of acetonitrile at a molar ratio of 1:4, and pre-complexed at 30 °C for 5 h. The resulting system was a homogeneous solution without visible precipitate. 0.500 g of the vinylized nucleus of this example (the mass ratio of the vinylized nucleus to 4-vinylpyridine was 500:421), 2.775 g (14.00 mmol) of ethylene glycol dimethacrylate, and 0.020 g (0.12 mmol) of 2,2-azobisisobutyronitrile were added to the above system, wherein the molar ratio of 1,2,3-trichlorobenzene, 4-vinylpyridine, ethylene glycol dimethacrylate, and 2,2-azobisisobutyronitrile was 1:4:14:0.12. The system was purged with nitrogen three times (approximately 5 minutes each time), for a total of 20 minutes. Positive pressure was maintained throughout the process using a nitrogen balloon. Polymerization was carried out at 63°C for 16 hours under nitrogen protection. Elution was performed five times (30.0 mL each time) with a methanol to glacial acetic acid eluent at a volume ratio of 10:1. The elution endpoint was determined by external standard gas chromatography (GC-MS) with a 1,2,3-trichlorobenzene content below 0.01 μg / mL. The particles were dried at 50°C for 6 hours to obtain core-shell composite particles with a molecularly imprinted polymer shell thickness of 17 nm. The shell thickness was determined using cross-sectional transmission electron microscopy. The residual 1,2,3-trichlorobenzene content in the core-shell composite particles after template elution was quantitatively determined by GC-MS using external standard gas chromatography (calculated based on the total dry weight of the eluted core-shell composite particles). The measured value was 0.28 wt%, not exceeding 0.5 wt%. In this embodiment, the vinylized core accounts for 60 wt% of the total mass of the core-shell composite particles, and the molecularly imprinted polymer shell accounts for 40 wt%, with the sum of their mass fractions being 100 wt%.

[0086] (4) Formation of anchoring layer and composite extraction recognition coating

[0087] A 160 μm diameter 304 stainless steel wire was washed three times each with ethanol and deionized water and then dried. 3-Aminopropyltriethoxysilane and tetraethoxysilane were added to a hydrolysis system consisting of 40.0 mL of ethanol, 5.0 mL of deionized water, and 1.0 mL of 25% ammonia (volume ratio 40:5:1) at a molar ratio of 1:2, and hydrolyzed at 35°C for 2 hours. The core-shell composite particles of this embodiment were ultrasonically dispersed in the above hydrolysis system at a concentration of 10.0 g / L. The 304 stainless steel wire substrate of this embodiment was coated in the dispersion using a dip-coating method. The pull-up rate was 2 mm / s, the single immersion time was 10 s, and a total of 5 coatings were performed. Between adjacent coatings, the substrate was allowed to dry at 25°C for 10 minutes. The 1,2,3-trichlorobenzene detection and analysis material of this embodiment was obtained by curing at 95℃ for 1.2 h. The composite extraction identification coating thickness was 11 μm, the effective coating length was 15 mm, and the anchoring layer thickness was 500 nm. The thicknesses of both the composite extraction identification coating and the anchoring layer were measured using cross-sectional scanning electron microscopy. The anchoring layer in this embodiment consists of a Si-O-Si network layer formed by the condensation of 3-aminopropyltriethoxysilane and tetraethoxysilane. The Si-O-Si network structure is connected to the surface of the 304 stainless steel wire substrate through Si-O-metal covalent bonds. The anchoring layer in this embodiment fixes the core-shell composite particles through the physical embedding of the siloxane network. Before use, the 1,2,3-trichlorobenzene detection and analysis material of this embodiment was aged at 230℃ for 30 min.

[0088] This embodiment is applicable to the solid-phase microextraction enrichment and quantitative analysis of 1,2,3-trichlorobenzene in conventional water quality matrices such as surface water, drinking water and general industrial wastewater, using gas chromatography or gas chromatography-mass spectrometry. It is also suitable for standardized routine monitoring procedures with manual or automatic sample introduction devices, and is a robust solution for general water quality testing.

[0089] Example 2

[0090] (1) Preparation of covalent organic framework cores linked by β-keto-enamine bonds

[0091] Weigh 0.500 g (2.38 mmol) of 2,4,6-tricarboxymethyl phloroglucinol and 0.342 g (3.16 mmol) of p-phenylenediamine, with a molar ratio of 1:1.33. Add them to a mixed solvent consisting of 7.0 mL of 1,4-dioxane, 7.0 mL of 1,3,5-trimethylbenzene, and 1.5 mL of glacial acetic acid (volume ratio 7:7:1.5, total volume 15.5 mL). Sonicate for 5 min to ensure homogeneity. Purge the system with nitrogen three times (approximately 5 min each time), maintaining a positive pressure inert atmosphere throughout the process using a nitrogen balloon. Transfer the mixture to a sealed reactor and react at 123 °C for 56 h. After the reaction was completed and cooled to room temperature, the solution was first washed three times with ethanol (25.0 mL each time, with the endpoint determined by the absorbance of the washing solution at 254 nm being less than 0.01 using a UV-Vis spectrophotometer), and then washed three times with methanol (25.0 mL each time, with the endpoint determined by the same criteria). The solution was then vacuum dried at 73 °C and a vacuum degree of -0.095 MPa for 13 h to obtain a covalent organic framework core with β-keto-enamine bonds and a number average particle size of 190 nm. The number average particle size was determined by statistical analysis of transmission electron microscopy images.

[0092] (2) Preparation of vinyl nuclei

[0093] The β-ketoenamine-linked covalent organic framework core of this embodiment was dispersed at an initial concentration of 5.0 g / L in a mixture of 93.8 mL of ethanol and 6.2 mL of deionized water (volume ratio 15:1, total volume 100.0 mL), and ultrasonically dispersed for 30 min. The pH was adjusted to 5.1 with glacial acetic acid. 3-(methacryloyloxy)propyltrimethoxysilane was added to the β-ketoenamine-linked covalent organic framework core of this embodiment at a mass ratio of 100:15, and the reaction was carried out at 66 °C for 6 h. After the reaction, the core was washed three times with ethanol (30.0 mL each time), and then vacuum dried at 63 °C and a vacuum degree of -0.095 MPa for 9 h to obtain the vinylized core of this embodiment. The vinylized nucleus of this embodiment was extracted with ethanol by Soxhlet extraction for 30 min to remove physically adsorbed components. After being vacuum dried at 70 °C until the mass was constant, the weight loss in the temperature range of 200–500 °C was determined by thermogravimetric analysis. The grafting amount of 3-(methacryloyloxy)propyltrimethoxysilane was calculated to be 0.58 mmol / g based on the dry basis mass of the vinylized nucleus.

[0094] (3) Preparation of core-shell composite particles

[0095] 0.181 g (1.00 mmol) of 1,2,3-trichlorobenzene and 0.526 g (5.00 mmol) of 4-vinylpyridine were added to 10.0 mL of acetonitrile at a molar ratio of 1:5, and pre-complexed at 33 °C for 6 h. The resulting system was a homogeneous solution without visible precipitate. 0.500 g of the vinylized nucleus of this example (the mass ratio of the vinylized nucleus to 4-vinylpyridine was 500:526), ​​3.172 g (16.00 mmol) of ethylene glycol dimethacrylate, and 0.025 g (0.15 mmol) of 2,2-azobisisobutyronitrile were added to the above system, wherein the molar ratio of 1,2,3-trichlorobenzene, 4-vinylpyridine, ethylene glycol dimethacrylate, and 2,2-azobisisobutyronitrile was 1:5:16:0.15. The system was purged with nitrogen three times (approximately 5 minutes each time), for a total of 23 minutes. Positive pressure was maintained throughout the process using a nitrogen balloon. Polymerization was carried out at 65°C for 18 hours under nitrogen protection. Elution was performed six times (30.0 mL each time) with a methanol to glacial acetic acid eluent at a volume ratio of 11:1. The elution endpoint was determined by external standard gas chromatography (GC) with a 1,2,3-trichlorobenzene content below 0.01 μg / mL. The particles were dried at 53°C for 8 hours to obtain core-shell composite particles with a molecularly imprinted polymer shell thickness of 21 nm. The shell thickness was determined using cross-sectional transmission electron microscopy. The residual 1,2,3-trichlorobenzene content in the core-shell composite particles after template elution was quantitatively determined by external standard gas chromatography (calculated based on the total dry weight of the eluted core-shell composite particles). The measured value was 0.21 wt%, not exceeding 0.5 wt%. In this embodiment, the vinylized nucleus accounts for 66 wt% of the total mass of the core-shell composite particles, and the molecularly imprinted polymer shell accounts for 34 wt%, with the sum of their mass fractions being 100 wt%.

[0096] (4) Formation of anchoring layer and composite extraction recognition coating

[0097] Titanium wire with a diameter of 210 μm was washed three times each with ethanol and deionized water and then dried. 3-Aminopropyltriethoxysilane and tetraethoxysilane were added at a molar ratio of 1:2.8 to a hydrolysis system consisting of 46.0 mL of ethanol, 7.0 mL of deionized water, and 1.3 mL of 25% ammonia (volume ratio 46:7:1.3), and hydrolyzed at 38 °C for 3 h. The core-shell composite particles of this embodiment were ultrasonically dispersed in the above hydrolysis system at a concentration of 13.0 g / L. The titanium wire substrate of this embodiment was coated in the dispersion using a dip-coating method. The pull-up rate was 2 mm / s, the single dip time was 10 s, and a total of 7 coatings were performed. Between adjacent coatings, the substrate was allowed to dry at 25 °C for 10 min. The 1,2,3-trichlorobenzene detection and analysis material of this embodiment was obtained by curing at 100℃ for 1.5 h. The composite extraction identification coating thickness was 14 μm, the effective coating length was 21 mm, and the anchoring layer thickness was 670 nm. The thicknesses of both the composite extraction identification coating and the anchoring layer were measured using cross-sectional scanning electron microscopy. The anchoring layer in this embodiment consists of a Si-O-Si network layer formed by the condensation of 3-aminopropyltriethoxysilane and tetraethoxysilane. The Si-O-Si network structure is connected to the titanium wire substrate surface through Si-O-metal covalent bonds. The anchoring layer fixes the core-shell composite particles of this embodiment through the physical embedding of the siloxane network. Before use, the 1,2,3-trichlorobenzene detection and analysis material of this embodiment was aged at 245℃ for 40 min.

[0098] This embodiment is applicable to the trace extraction analysis of 1,2,3-trichlorobenzene in complex sample matrices with high organic matter interference (such as groundwater, petrochemical wastewater, dyeing and printing wastewater and sludge leachate). It can be coupled with high-sensitivity gas chromatography-mass spectrometry to achieve quantitative detection at the pg / mL level. It is also suitable for long-term online monitoring devices that need to be reused multiple times and high-frequency automatic sample injection coupling systems.

[0099] Example 3

[0100] (1) Preparation of covalent organic framework cores linked by β-keto-enamine bonds

[0101] Weigh 0.500 g (2.38 mmol) of 2,4,6-tricarboxymethyl phloroglucinol and 0.309 g (2.85 mmol) of p-phenylenediamine, with a molar ratio of 1:1.20. Add them to a mixed solvent (volume ratio 5:5:1, total volume 11.0 mL) consisting of 5.0 mL of 1,4-dioxane, 5.0 mL of 1,3,5-trimethylbenzene, and 1.0 mL of glacial acetic acid. Sonicate for 5 min to ensure homogeneity. Purge the system with nitrogen three times (approximately 5 min each time), maintaining a positive pressure inert atmosphere throughout the process using a nitrogen balloon. Transfer the mixture to a sealed reactor and react at 117 °C for 40 h. After the reaction was completed and cooled to room temperature, the solution was first washed three times with ethanol (20.0 mL each time, with the endpoint determined by the absorbance of the washing solution at 254 nm being less than 0.01 using a UV-Vis spectrophotometer), and then washed three times with methanol (20.0 mL each time, with the endpoint determined by the same criteria). The solution was then vacuum dried at 68 °C and a vacuum degree of -0.095 MPa for 11 h to obtain a covalent organic framework core with β-keto-enamine bonds and a number average particle size of 145 nm. The number average particle size was determined by statistical analysis of transmission electron microscopy images.

[0102] (2) Preparation of vinyl nuclei

[0103] The β-ketoenamine-linked covalent organic framework core of this embodiment was dispersed at an initial concentration of 5.0 g / L in a mixture of 90.9 mL of ethanol and 9.1 mL of deionized water (volume ratio 10:1, total volume 100.0 mL), and ultrasonically dispersed for 30 min. The pH was adjusted to 4.9 with glacial acetic acid. 3-(methacryloyloxy)propyltrimethoxysilane was added to the β-ketoenamine-linked covalent organic framework core of this embodiment at a mass ratio of 100:10, and the reaction was carried out at 60 °C for 4 h. After the reaction, the core was washed three times with ethanol (30.0 mL each time), and then vacuum dried at 58 °C and a vacuum degree of -0.095 MPa for 7 h to obtain the vinylized core of this embodiment. The vinylized nucleus of this embodiment was extracted with ethanol by Soxhlet extraction for 30 min to remove physically adsorbed components. After being vacuum dried at 70 °C until the mass was constant, the weight loss in the temperature range of 200–500 °C was determined by thermogravimetric analysis. The grafting amount of 3-(methacryloyloxy)propyltrimethoxysilane was calculated to be 0.42 mmol / g based on the dry basis mass of the vinylized nucleus.

[0104] (3) Preparation of core-shell composite particles

[0105] 0.181 g (1.00 mmol) of 1,2,3-trichlorobenzene and 0.315 g (3.00 mmol) of 4-vinylpyridine were added to 10.0 mL of acetonitrile at a molar ratio of 1:3, and pre-complexed at 28 °C for 4 h. The resulting system was a homogeneous solution without visible precipitate. 0.500 g of the vinylized nucleus of this example (the mass ratio of the vinylized nucleus to 4-vinylpyridine was 500:315), 2.378 g (12.00 mmol) of ethylene glycol dimethacrylate, and 0.016 g (0.10 mmol) of 2,2-azobisisobutyronitrile were added to the above system, wherein the molar ratio of 1,2,3-trichlorobenzene, 4-vinylpyridine, ethylene glycol dimethacrylate, and 2,2-azobisisobutyronitrile was 1:3:12:0.10. The system was purged with nitrogen three times (approximately 5 minutes each time), for a total of 17 minutes. Positive pressure was maintained throughout the process using a nitrogen balloon. Polymerization was carried out at 60°C for 14 hours under nitrogen protection. Elution was performed five times (30.0 mL each time) with a methanol / glacial acetic acid eluent at a volume ratio of 10:1. The elution endpoint was determined by external standard gas chromatography (GC-MS) with a 1,2,3-trichlorobenzene content below 0.01 μg / mL. The particles were dried at 48°C for 6 hours to obtain core-shell composite particles with a molecularly imprinted polymer shell thickness of 14 nm. The shell thickness was determined using cross-sectional transmission electron microscopy. The residual 1,2,3-trichlorobenzene content in the core-shell composite particles after template elution was quantitatively determined by GC-MS using external standard gas chromatography (calculated based on the total dry weight of the eluted core-shell composite particles). The measured value was 0.31 wt%, not exceeding 0.5 wt%. In this embodiment, the vinylized core accounts for 55 wt% of the total mass of the core-shell composite particles, and the molecularly imprinted polymer shell accounts for 45 wt%, with the sum of their mass fractions being 100 wt%.

[0106] (4) Formation of anchoring layer and composite extraction recognition coating

[0107] Quartz fibers with a diameter of 145 μm were washed three times each with ethanol and deionized water and then dried. 3-Aminopropyltriethoxysilane and tetraethoxysilane were added at a molar ratio of 1:1.8 to a hydrolysis system consisting of 35.0 mL of ethanol, 4.0 mL of deionized water, and 0.8 mL of 25% ammonia (volume ratio 35:4:0.8), and hydrolyzed at 33°C for 1.8 h. The core-shell composite particles of this embodiment were ultrasonically dispersed in the above hydrolysis system at a concentration of 8.0 g / L. The quartz fiber substrate of this embodiment was continuously passed through a coating tank containing the core-shell composite particle dispersion system using a stretch coating method at a coating rate of 3 mm / s, for a total of four coatings. Between each coating, the substrate was allowed to air dry at 25°C for 10 min. The 1,2,3-trichlorobenzene detection and analysis material of this embodiment was obtained by curing at 90℃ for 1.0 h. The composite extraction identification coating thickness was 9 μm, the effective coating length was 15 mm, and the anchoring layer thickness was 410 nm. The thicknesses of both the composite extraction identification coating and the anchoring layer were measured using cross-sectional scanning electron microscopy. The anchoring layer of this embodiment consists of a Si-O-Si network layer formed by the condensation of 3-aminopropyltriethoxysilane and tetraethoxysilane. The Si-O-Si network structure is connected to the surface of the quartz fiber substrate of this embodiment through Si-O-Si covalent bonds. The anchoring layer fixes the core-shell composite particles of this embodiment through the physical embedding of the siloxane network. Before use, the 1,2,3-trichlorobenzene detection and analysis material of this embodiment was activated in methanol at 55℃ for 20 min in a sealed container.

[0108] This embodiment is suitable for rapid detection scenarios with strict extraction equilibrium time requirements, such as online flow injection analysis systems, portable on-site detection devices, and headspace solid-phase microextraction with short exposure. It is also suitable for the enrichment analysis of 1,2,3-trichlorobenzene in highly corrosive media (strong acid mine wastewater, alkaline saponification waste liquid), and can also be applied to trace analysis of chlorobenzene series compounds in methanol extract of atmospheric particulate matter.

[0109] Example 4

[0110] (1) Preparation of covalent organic framework cores linked by β-keto-enamine bonds

[0111] Weigh 0.500 g (2.38 mmol) of 2,4,6-tricarboxymethyl phloroglucinol and 0.322 g (2.98 mmol) of p-phenylenediamine, with a molar ratio of 1:1.25. Add them to a mixed solvent (volume ratio 6:6:1, total volume 13.0 mL) consisting of 6.0 mL of 1,4-dioxane, 6.0 mL of 1,3,5-trimethylbenzene, and 1.0 mL of glacial acetic acid. Sonicate for 5 min to ensure homogeneity. Purge the system with nitrogen three times (approximately 5 min each time), maintaining a positive pressure inert atmosphere throughout the process using a nitrogen balloon. Transfer the mixture to a sealed reactor and react at 125 °C for 60 h. After the reaction was completed and cooled to room temperature, the solution was first washed three times with ethanol (20.0 mL each time, with the endpoint determined by the absorbance of the washing solution at 254 nm being less than 0.01 using a UV-Vis spectrophotometer), and then washed three times with methanol (20.0 mL each time, with the endpoint determined by the same criteria). The solution was then vacuum dried at 70 °C and a vacuum degree of -0.095 MPa for 12 h to obtain a covalent organic framework core with β-keto-enamine bonds and a number average particle size of 235 nm. The number average particle size was determined by statistical analysis of transmission electron microscopy images.

[0112] (2) Preparation of vinyl nuclei

[0113] The β-ketoenamine-linked covalent organic framework core of this embodiment was dispersed at an initial concentration of 5.0 g / L in a mixture of 92.3 mL of ethanol and 7.7 mL of deionized water (volume ratio 12:1, total volume 100.0 mL), and ultrasonically dispersed for 30 min. The pH was adjusted to 5.0 with glacial acetic acid. 3-(methacryloyloxy)propyltrimethoxysilane was added to the β-ketoenamine-linked covalent organic framework core of this embodiment at a mass ratio of 100:12, and the reaction was carried out at 62 °C for 5 h. After the reaction, the core was washed three times with ethanol (30.0 mL each time), and then vacuum dried at 60 °C and a vacuum degree of -0.095 MPa for 8 h to obtain the vinylized core of this embodiment. The vinylized nucleus of this embodiment was extracted with ethanol by Soxhlet extraction for 30 min to remove physically adsorbed components. After being vacuum dried at 70°C until the mass was constant, the weight loss in the temperature range of 200–500°C was determined by thermogravimetric analysis. The grafting amount of 3-(methacryloyloxy)propyltrimethoxysilane was calculated to be 0.50 mmol / g based on the dry basis mass of the vinylized nucleus.

[0114] (3) Preparation of core-shell composite particles

[0115] 0.181 g (1.00 mmol) of 1,2,3-trichlorobenzene and 0.421 g (4.00 mmol) of 4-vinylpyridine were added to 10.0 mL of acetonitrile at a molar ratio of 1:4, and pre-complexed at 30 °C for 5 h. The resulting system was a homogeneous solution without visible precipitate. 0.500 g of the vinylized nucleus of this example (the mass ratio of the vinylized nucleus to 4-vinylpyridine was 500:421), 2.775 g (14.00 mmol) of ethylene glycol dimethacrylate, and 0.020 g (0.12 mmol) of 2,2-azobisisobutyronitrile were added to the above system, wherein the molar ratio of 1,2,3-trichlorobenzene, 4-vinylpyridine, ethylene glycol dimethacrylate, and 2,2-azobisisobutyronitrile was 1:4:14:0.12. The system was purged with nitrogen three times (approximately 5 minutes each time), for a total of 20 minutes, with positive pressure maintained throughout using a nitrogen balloon. Polymerization was carried out at 63°C for 16 hours under nitrogen protection. Elution was performed five times (30.0 mL each time) with a methanol to glacial acetic acid eluent at a volume ratio of 10:1. The elution endpoint was determined by external standard gas chromatography (GC) with a 1,2,3-trichlorobenzene content below 0.01 μg / mL. The particles were dried at 50°C for 6 hours to obtain core-shell composite particles with a molecularly imprinted polymer shell thickness of 17 nm. The shell thickness was determined by cross-sectional transmission electron microscopy. The residual 1,2,3-trichlorobenzene content in the core-shell composite particles after template elution was quantitatively determined by external standard gas chromatography (calculated based on the total dry weight of the eluted core-shell composite particles). The measured value was 0.29 wt%, not exceeding 0.5 wt%. In this embodiment, the vinylized core accounts for 60 wt% of the total mass of the core-shell composite particles, and the molecularly imprinted polymer shell accounts for 40 wt%, with the sum of their mass fractions being 100 wt%.

[0116] (4) Formation of anchoring layer and composite extraction recognition coating

[0117] Glass fibers with a diameter of 160 μm were washed three times each with ethanol and deionized water and then dried. 3-Aminopropyltriethoxysilane and tetraethoxysilane were added at a molar ratio of 1:0.7 to a hydrolysis system consisting of 40.0 mL of ethanol, 5.0 mL of deionized water, and 1.0 mL of 25% ammonia (volume ratio 40:5:1), and hydrolyzed at 35°C for 2 h. The core-shell composite particles of this embodiment were ultrasonically dispersed in the above hydrolysis system at a concentration of 8.0 g / L. The glass fiber substrate of this embodiment was coated in the dispersion using a dip-coating method. The pull-up rate was 2 mm / s, the single dip time was 10 s, and a total of 6 coatings were performed. Between adjacent coatings, the substrate was allowed to dry at 25°C for 10 min. The 1,2,3-trichlorobenzene detection and analysis material of this embodiment was obtained by curing at 95℃ for 1.2 h. The composite extraction and identification coating thickness was 10 μm, the effective coating length was 20 mm, and the anchoring layer thickness was 350 nm. The thicknesses of both the composite extraction and identification coating and the anchoring layer were measured using cross-sectional scanning electron microscopy. The anchoring layer in this embodiment consists of a Si-O-Si network layer formed by the condensation of 3-aminopropyltriethoxysilane and tetraethoxysilane. The Si-O-Si network structure is connected to the glass fiber substrate surface through Si-O-Si covalent bonds. The anchoring layer effectively immobilizes the core-shell composite particles through the physical embedding of the siloxane network. Before use, the 1,2,3-trichlorobenzene detection and analysis material of this embodiment was aged at 230℃ for 30 min.

[0118] This embodiment is applicable to the high-capacity enrichment and quantitative analysis of 1,2,3-trichlorobenzene in methanol leachate from groundwater, nearshore seawater, and atmospheric particulate matter using gas chromatography. It is also suitable for the technical evaluation and method development of solid-phase nanoextraction devices, as well as for flow injection online extraction enrichment scenarios that require materials with strong impact resistance.

[0119] Comparative Example 1: Basically the same as Example 1, except that the covalent organic framework core linked by β-keto-enamine bonds was replaced with a silica core with a number average particle size of 165 nm, and 3-(methacryloyloxy)propyltrimethoxysilane vinylation and subsequent polymerization were carried out on the surface of the silica core to form core-shell composite particles, with other conditions remaining unchanged.

[0120] Comparative Example 2: It is basically the same as Example 1, except that the 3-(methacryloyloxy)propyltrimethoxysilane vinylation step is omitted, so that the covalent organic framework core linked by β-ketoenamine bonds is directly polymerized to form core-shell composite particles without vinylation, and other conditions remain unchanged.

[0121] Comparative Example 3: It is basically the same as Example 1, except that 1,2,3-trichlorobenzene template molecules are not added in the polymerization step. Surface polymerization is still carried out using 4-vinylpyridine as the functional monomer, ethylene glycol dimethacrylate as the crosslinking agent, and 2,2-azobisisobutyronitrile as the initiator, and then dried to obtain core-shell composite particles. Other conditions remain unchanged.

[0122] Comparative Example 4: Basically the same as Example 1, except that the polymerization time was set to 30h in the polymerization step to obtain core-shell composite particles with a shell thickness of 40nm, while other conditions remained unchanged.

[0123] Comparative Example 5: It is basically the same as Example 1, except that the Si-O-Si network anchoring layer formed by the condensation of 3-aminopropyltriethoxysilane and tetraethoxysilane is omitted. Instead, the core-shell composite particles are dispersed in ethanol and directly dipped onto the substrate surface and cured to form a composite extraction recognition coating. Other conditions remain unchanged.

[0124] Comparative Example 6: Basically the same as Example 1, except that the molar ratio of 3-aminopropyltriethoxysilane to tetraethoxysilane in the hydrolysis condensation system was set to 1:5 to form an anchoring layer and fix the core-shell composite particles, while other conditions remained unchanged.

[0125] Comparative Example 7: Basically the same as Example 1, except that the dispersion concentration of the core-shell composite particles in the hydrolysis system was set to 25.0 g / L in the coating step, and the same dip-coating and pulling rate and coating times were used to form a composite extraction recognition coating, with other conditions remaining unchanged.

[0126] Comparative Example 8: It is basically the same as Example 1, except that the curing temperature is set to 60°C and the curing time is kept to 1.2h to obtain a composite extraction recognition coating, while other conditions remain unchanged.

[0127] Performance testing:

[0128] Experiment 1: Using 1,2,3-trichlorobenzene from the examples and comparative examples, the contribution of the Si–O–Si anchoring layer to the coating adhesion stability was verified based on the principle that interfacial pull-off strength characterizes adhesion work and network curing degree. Coatings were prepared on metal sheets of the same material under the same sol-gel coating and curing conditions. The adhesion strength was tested using the pull-off method, and the failure morphology was recorded. The test conditions were 23±2℃, 50±10%RH, and the number of parallel samples n=5. Data are expressed as mean ± standard deviation, and the proportions of interfacial / cohesive / mixed failures were statistically analyzed.

[0129] Experiment 2: Using the coating substrates from the examples and comparative examples, this experiment evaluates the compatibility between "high adhesion and abrasion resistance" and coating integrity, based on the principle that frictional abrasion leads to coating quality / thickness degradation and performance drift. A standard abrasion wheel was used to abrade the coating under specified loads and rotational speeds (500g load, 1000 abrasion cycles), with 3 parallel samples. The coating thickness was measured before and after abrasion, and the enrichment factor retention rate was tested. Data are presented in parallel as abrasion loss (mg / 1000 cycles) and enrichment factor retention rate (%), expressed as mean ± standard deviation.

[0130] Experiment 3: Using the composite extraction identification coatings from the examples and comparative examples, based on the principle that thickness and uniformity affect capacity and mass transfer and are coupled with dispersion viscosity, manufacturability and coating consistency (thickness window and batch-to-batch stability) were verified. Cross-sectional SEM thickness measurements were performed at ≥10 locations along the effective coating length, and the relative standard deviation was calculated. Three samples were prepared for both the same batch and across batches, with the accelerating voltage and sampling locations fixed. Data output included the mean ± standard deviation of thickness and the percentage of relative standard deviation, and analysis of variance was performed on the batch-to-batch relative standard deviation.

[0131] Experiment 4: Using core-shell composite particles (dry powder) and scraped coatings (if feasible) from the examples and comparative cases, the structural basis of "high porosity, high mass transfer kinetics" was verified based on the principle that the BET specific surface area and pore volume reflect accessible sites and diffusion channels during N2 adsorption. After degassing the samples at 120℃ for ≥6h, N2 adsorption-desorption tests were performed, and the BET specific surface area, total pore volume, and BJH pore size distribution were calculated. The mean ± standard deviation (n=3) of specific surface area / pore volume / major pore size were output, and correlation analysis with t90 was performed.

[0132] Experiment 5: Using the fiber / filament-based SPME materials from the examples and comparative studies, the enrichment capacity, linearity, and selectivity of 1,2,3-trichlorobenzene were evaluated based on the principle that partition-adsorption equilibrium determines the enrichment factor and molecularly imprinted sites determine the selectivity coefficient. A mixed water sample containing 1,2,3-trichlorobenzene and an internal control of 1,2,4-trichlorobenzene was prepared. SPME extraction was performed at 25°C and 500 rpm for 20 min, followed by quantification by GC or GC-MS (desorption at 250°C for 2 min). The enrichment factor and selectivity coefficient were calculated. Calibration curves (R²), enrichment factors, and selectivity coefficients are expressed as mean ± standard deviation (n=5).

[0133] Experiment 6: Using the SPME materials from the examples and comparative studies, the coupling relationship between mass transfer kinetics and "thickness / pore structure" was verified based on the principle that the response-time curve can be fitted using a pseudo-first-order model. Extraction time points of 1, 2, 5, 10, 15, 20, and 30 min were set at a fixed initial concentration. Peak areas were measured and t90 was obtained under conditions of 25℃ and stirring at 500 rpm. The mean ± standard deviation of t90 (n=3) and the goodness of fit are given, and scatter correlation analysis was performed with coating thickness / specific surface area.

[0134] Experiment 7: Using core-shell composite particles and SPME materials from the examples and comparative studies, based on the principle that template residue and blank carryover rate after desorption reflect retention and slow release, the risk of "strong recognition-low residue and fast desorption" and memory effect was evaluated. Template residue (wt%) of the core-shell composite particles was quantified by external standard GC, and carryover rate was measured by "one-time extraction-desorption-blank re-injection of high-concentration samples." Blank carryover rate was calculated as blank peak area / previous injection peak area × 100%, with 5 parallel samples. Residue and carryover rates were output as mean ± standard deviation, and it was determined whether the low carryover threshold was met.

[0135] Figure 1 This is a superimposed plot of N2 adsorption-desorption isotherms. Samples 1, 1 (Comparative Example), and 4 (Comparative Example) were selected. Nitrogen adsorption-desorption tests were used to obtain the relative pressure (P / P0) versus adsorption capacity curves. The basic parameters were: test temperature 77 K, horizontal axis P / P0 range 0 to 1, and vertical axis adsorption capacity (cm³·g). -1 The study also demonstrated the adsorption and desorption branches, with the variable parameters being the differences in hysteresis ring morphology and adsorption capacity levels caused by the pore structure characteristics of different samples. The conclusion was that Example 1 exhibited an isotherm that was more consistent with the characteristics of mesoporous materials and had a better adsorption capacity, indicating that its pore structure was more fully constructed, which was beneficial to the subsequent mass transfer and enrichment process, thus demonstrating the rationality of the scheme.

[0136] Figure 2 To illustrate the differential distribution curves of the BJH pore size distribution, samples 1 (Example 1), 1 (Comparative Example 1), and 4 (Comparative Example 4) were selected. The pore size distribution of nitrogen adsorption data was calculated using the BJH method. The basic parameters were: horizontal axis pore size D (unit: nm) on a logarithmic scale, and vertical axis dV / dlogD (unit: cm³·g). -1 The pore size range covers approximately 2 to 50 nm. The variable parameters are the position and width of the main peak pore size of different samples, reflecting the difference in mesopore concentration. The conclusion is that Example 1 presents a more concentrated pore size distribution and a more reasonable mesopore size, indicating that its pores are more conducive to the entry and diffusion of target molecules, supporting the correctness of the structural design.

[0137] Figure 3To plot the cumulative pore volume distribution curve of BJH, samples 1, 1 (Comparative Example), and 4 (Comparative Example) were selected. The cumulative pore volume curve was obtained by integrating the differential distribution of BJH. The basic parameters are: horizontal axis pore diameter D in nm (logarithmic scale) and vertical axis cumulative pore volume in cm³·g. -1 Furthermore, the curve increases monotonically with pore size. The variable parameters are the growth rate of cumulative pore volume and the final plateau value of different samples within the same pore size range. The conclusion is that Example 1 contributes a higher cumulative pore volume in the effective pore size range, indicating that its usable pore volume is more sufficient. It can provide more effective sites while ensuring structural integrity, reflecting the rationality of the scheme.

[0138] Figure 4 To plot the mean plus standard deviation band of EF-time kinetics, samples Example 1, Comparative Example 1, and Comparative Example 4 were selected. Enrichment experiments were conducted under stirring conditions, and the kinetic process was characterized by the change of EF over time. The basic parameters were the extraction time t (unit: min) on the horizontal axis, covering 1 to 30, and the enrichment factor EF on the vertical axis. The mean curve and standard deviation band were plotted. The variable parameters were the differences in the rate of increase and final enrichment capacity caused by the t90 and the plateau EF level of different samples. The conclusion is that Example 1 reached a higher EF in a shorter time and had a faster trend toward equilibrium, indicating that it had lower mass transfer resistance and a more sufficient effective interface, verifying the supporting role of the scheme for rapid enrichment.

[0139] Figure 5 For the TGA mass-temperature overlay, Sample Example 1 and Comparative Example 2 were selected. Thermogravimetric analysis was used to obtain the mass change with increasing temperature. The basic parameters were: horizontal axis temperature T in °C covering approximately 50 to 800, and vertical axis mass in wt%. Two curves were used to compare thermal stability and the weight loss stage. The variable parameters were the weight loss amplitude and residual mass difference of different samples in the low temperature and medium-high temperature ranges. The conclusion is that Sample 1 showed more expected segmented weight loss and more stable mass retention, indicating that its component structure and interface bonding were more stable, supporting the rationality of the scheme from the perspective of thermal stability.

[0140] Figure 6 For the DTG mass change rate versus temperature overlay plot, Sample Example 1 and Comparative Example 2 were selected. The DTG peaks were obtained by differentiating the TG curves to analyze the weight loss process. The basic parameters were: horizontal axis temperature T in °C covering approximately 50 to 800 °C, and vertical axis dMass / dT. The peak positions and peak intensities were compared. The variable parameters were the differences in the volatilization or decomposition processes corresponding to the temperature positions and peak areas of the main weight loss peaks of different samples. The conclusion is that the DTG characteristic peaks of Sample 1 are more concentrated and the peak positions are more reasonable, indicating that its key components are more stable and there are fewer weak binding compounds, which is beneficial to improving the stability of the material during use and further proves the correctness of the scheme.

[0141] Figure 7For the XPS narrow-area spectrum of Si2p, Sample 1 and Comparative Sample 2 were selected. X-ray photoelectron spectroscopy was used to analyze the chemical state of Si2p. The basic parameters were the binding energy (eV) on the horizontal axis using a common reverse coordinate system and the intensity (au) on the vertical axis. The peak shape and position were compared. The variable parameters were the peak position shift and peak shape differences caused by the chemical bonding environment of Si in different samples. The conclusion is that Sample 1 presents a spectral shape that is more consistent with the formation of silicon-oxygen networks, indicating that its surface chemical bonding is more complete, which helps to form a stable interface and functional layer structure, and supports the rationality of the scheme from the chemical state level.

[0142] Figure 8 For the overlay of N1s NPS narrow-area spectrum, samples 1 and 2 were selected. The chemical state of N1s was analyzed by X-ray photoelectron spectroscopy. The basic parameters were the horizontal axis binding energy in units of eV (reverse direction) and the vertical axis intensity in au. The peak shape contribution of different nitrogen species was compared. The variable parameters were the spectral changes caused by the difference in the proportion of nitrogen-containing functional groups and the binding state of different samples. The conclusion is that the N1s spectrum of Example 1 shows that its nitrogen-containing sites participate more effectively in interfacial interactions and functional construction, which is beneficial to improving surface activity and binding stability, proving that the chemical design of the scheme is reasonable.

[0143] Figure 9 This is a macroscopic optical photograph of the β-ketoenamine-linked covalent organic framework core prepared in Example 1. The basic parameters were a 1:1.25 molar ratio of 2,4,6-tricarboxymethyl phloroglucinol to p-phenylenediamine and a sealed solvothermal reaction at 120°C for 48 h, with material concentration as a potential variable parameter. The sample as a whole is a uniform deep orange matte powder without visible agglomerates or color differences, which proves that the extended conjugated system constructed by the irreversible tautomerization reaction of β-ketoenamine endows the framework with characteristic absorption color. The solvothermal route can achieve the synthesis of macroscopically uniform nanopowders.

[0144] Figure 10 The image shows a macroscopic optical photograph of the core-shell composite particles prepared in Example 1. The parameters were based on a covalent organic framework core linked by β-keto-enamine bonds and 4-vinylpyridine at a mass ratio of 500:421 and free radical polymerization at 63°C for 16 hours. The molar ratio of functional monomers to crosslinking agents was used as a potential variable parameter. The overall color tone of the sample shifted towards a light orange compared to the pure core. The powder maintained good flowability, which proves that the uniform coating of the molecularly imprinted polymer shell changed the light scattering characteristics of the particle surface. The macroscopic color shift can indirectly reflect the degree of shell coverage.

[0145] Figure 11The image shows a macroscopic optical photograph of the 1,2,3-trichlorobenzene detection and analysis material prepared in Example 1. The basic parameters are a 304 stainless steel wire with a diameter of 160 μm, 5 dip-coatings (pulling rate of 2 mm / s), and curing at 95°C for 1.2 h. The number of dip-coatings is used as a variable parameter. The effectively coated section has a uniform orange-yellow semi-matte appearance with a length of 15 mm, forming a clear color difference interface with the uncoated section. There are no visible cracks or peeling. This proves that multiple dip-coatings combined with siloxane curing can form a continuous, uniform, macroscopically defect-free composite extraction and identification coating on a cylindrical metal substrate.

[0146] Figure 12 The image shown is a low-magnification scanning electron microscope (SEM) image of the β-ketoenamine bonded covalent organic framework nucleus prepared in Example 1. The sample was synthesized using a sealed solvothermal method at 120°C and purified by stepwise washing with ethanol and methanol. Within the large field of view, the sample was uniformly distributed as soft aggregates of 1–5 μm, without any hard lumps or heterogeneous impurities. This demonstrates that the sealed solvothermal synthesis and thorough purification steps together ensured the macroscopic uniformity of the nucleus powder distribution and batch stability.

[0147] Figure 13 The image shown is a bright-field transmission electron microscope (TEM) image of the β-ketoenamine-linked covalent organic framework core prepared in Example 1, with solvothermal synthesis as the basic parameter. The core particles are solid with uniform contrast, without hollow cavities, and slightly aggregated, proving that the covalent organic framework core formed by the solvothermal condensation of β-ketoenamine is a uniform and dense solid nanoparticle, and the particle size is consistent with the statistical measurement value of the transmission electron microscope image.

[0148] Table 1. Structural / Composition and Interface Mechanical Related Indicators of Examples and Comparative Examples

[0149] Sample number Coating thickness / μm Shell thickness / nm Anchoring layer thickness / nm Template residue / wt% Adhesion strength / MPa Abrasion loss (mg / 1000 cycles) Example 1 11.0±0.3 17±1 500±30 0.28±0.03 6.5±0.4 4.8±0.6 Example 2 14.0±0.4 21±1 670±40 0.21±0.02 6.8±0.4 4.5±0.5 Example 3 9.0±0.3 14±1 410±25 0.31±0.03 5.9±0.3 5.2±0.7 Example 4 10.0±0.3 17±1 350±25 0.29±0.03 5.4±0.3 5.5±0.6 Comparative Example 1 11.0±0.5 17±1 500±30 0.30±0.04 6.4±0.4 5.1±0.7 Comparative Example 2 11.0±0.8 17±4 500±30 0.38±0.05 4.2±0.6 8.9±1.2 Comparative Example 3 11.0±0.3 17±1 500±30 0.00±0.00 6.5±0.4 5.0±0.6 Comparative Example 4 12.0±0.4 40±3 500±30 0.48±0.05 5.8±0.5 6.4±0.9 Comparative Example 5 9.5±1.2 17±1 0±0 0.28±0.03 1.6±0.3 15.0±2.5 Comparative Example 6 11.0±0.4 17±1 900±60 0.27±0.03 7.2±0.4 4.2±0.5 Comparative Example 7 18.0±1.0 17±1 500±30 0.29±0.03 5.0±0.7 7.6±1.5 Comparative Example 8 11.0±0.4 17±1 500±30 0.28±0.03 2.3±0.4 12.5±2.0

[0150] Table 2 analyzes performance and kinetic related indicators.

[0151] Sample number Enrichment factor EF t90 / min Selectivity coefficient α Blank carryover rate / % Example 1 980±35 8.5±0.6 5.2±0.4 1.8±0.2 Example 2 1120±40 9.5±0.7 6.0±0.5 1.6±0.2 Example 3 860±30 6.0±0.5 4.4±0.3 1.2±0.1 Example 4 920±32 7.2±0.6 5.0±0.4 1.5±0.2 Comparative Example 1 650±25 11.5±1.0 3.1±0.3 2.5±0.3 Comparative Example 2 720±45 10.0±1.2 3.8±0.5 3.2±0.5 Comparative Example 3 540±20 7.0±0.6 1.2±0.2 0.6±0.1 Comparative Example 4 820±30 18.0±1.5 6.3±0.6 4.5±0.6 Comparative Example 5 600±50 9.0±1.4 5.1±0.4 2.0±0.4 Comparative Example 6 780±28 13.5±1.0 5.0±0.4 2.1±0.3 Comparative Example 7 1050±60 16.0±1.3 5.3±0.6 2.8±0.4 Comparative Example 8 760±45 10.5±1.0 5.1±0.5 2.4±0.4

[0152] As can be seen from the results of the examples and comparative examples in Table 1, Examples 1-4 achieved a more balanced overall performance in terms of adhesion strength, wear loss, EF, t90, and blank carryover rate: the anchoring layer provides a stable interface bond and reduces performance drift caused by wear; the pore structure of the core-shell composite particles and the moderate shell thickness keep EF high and t90 short, while template residue and carryover rate are at a low level; in contrast, in Comparative Example 1, core replacement leads to weakened pore structure and interaction, resulting in decreased EF and longer t90; in Comparative Example 2, the lack of vinylation causes insufficient shell stability and increased residue, and a significant increase in carryover rate; in Comparative Example 3, although the carryover rate is low, selectivity and EF are significantly insufficient; in Comparative Example 4, the excessively thick shell layer causes limited mass transfer and aggravated memory effect; in Comparative Example 5, the lack of an anchoring layer leads to significant deterioration of adhesion and wear resistance; in Comparative Example 6, the excessively dense network hinders mass transfer; in Comparative Example 7, the excessively high solid content causes a thick coating and limited desorption; in Comparative Example 8, low-temperature curing causes insufficient interface strength and amplifies wear failure.

[0153] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that any equivalent structural transformations made under the concept of the present invention and using the contents of the specification and drawings of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A material for the detection and analysis of 1,2,3-trichlorobenzene, characterized in that, Includes a substrate and a composite extraction recognition coating formed on the surface of the substrate, the composite extraction recognition coating comprising: a. A β-ketoenamine-linked covalent organic framework core, wherein the β-ketoenamine-linked covalent organic framework core is prepared by reacting 2,4,6-tricarboxymethylphloroglucinol with p-phenylenediamine; b. A molecularly imprinted polymer shell coating the surface of the β-ketoenamine-linked covalent organic framework core, wherein the β-ketoenamine-linked covalent organic framework core is vinylized with 3-(methacryloyloxy)propyltrimethoxysilane to obtain a vinylized core, and the molecularly imprinted polymer shell is formed by polymerization on the surface of the vinylized core using 1,2,3-trichlorobenzene as a template molecule, 4-vinylpyridine as a functional monomer, ethylene glycol dimethacrylate as a crosslinking agent, and 2,2-azobisisobutyronitrile as an initiator, followed by elution. The vinylized core and the molecularly imprinted polymer shell constitute a core-shell composite particle. c. An anchoring layer located between the substrate surface and the core-shell composite particles, wherein the anchoring layer is a Si-O-Si network layer formed by the condensation of 3-aminopropyltriethoxysilane and tetraethoxysilane, used to fix the core-shell composite particles to the substrate surface; The number-average particle size of the covalent organic framework core linked by the β-keto-enamine bond is 80-250 nm, the thickness of the molecularly imprinted polymer shell is 5-30 nm, the thickness of the composite extraction recognition coating is 3-20 μm, and the substrate is one of 304 stainless steel wire, titanium wire, quartz fiber, or glass fiber.

2. The 1,2,3-trichlorobenzene detection and analysis material as described in claim 1, characterized in that, The β-keto-enamine bonded covalent organic framework core is prepared by the following steps: A1. 2,4,6-tricarboxymethyl phloroglucinol and p-phenylenediamine are added to a mixed solvent composed of 1,4-dioxane, 1,3,5-trimethylbenzene and glacial acetic acid at a molar ratio of 1:1-1.5, wherein the volume ratio of 1,4-dioxane, 1,3,5-trimethylbenzene and glacial acetic acid is 4-8:4-8:0.5-2; A2. Transfer to a sealed reactor under nitrogen protection and react at 110-130℃ for 24-72 hours; A3. Wash with ethanol 2-4 times, then with methanol 2-4 times, and vacuum dry at 60-80℃ for 8-16 hours; A4. Obtain the covalent organic framework core body with β-keto-enamine bond linkage, and its number average particle size is 80-250 nm.

3. The 1,2,3-trichlorobenzene detection and analysis material as described in claim 2, characterized in that, The vinylized nucleus is prepared by the following steps: B1. The β-keto-enamine bonded covalent organic framework core is dispersed in a mixture of ethanol and deionized water, wherein the volume ratio of ethanol to deionized water is 5-20:1, and the pH is adjusted to 4.5-5.5 with glacial acetic acid. B2. Add 3-(methacryloyloxy)propyltrimethoxysilane to the covalent organic framework core linked by the β-ketoenamine bond at a mass ratio of 100:5-20, and react at 50-75°C for 2-8 hours. B3. After the reaction, wash with ethanol 2-4 times and dry under vacuum at 50-70℃ for 4-12 hours; B4. The vinyl nucleus is obtained, wherein the grafting amount of 3-(methacryloyloxy)propyltrimethoxysilane is 0.20-0.80 mmol / g.

4. The 1,2,3-trichlorobenzene detection and analysis material as described in claim 1, characterized in that, The molecularly imprinted polymer shell is prepared by the following steps: C1. Add 1,2,3-trichlorobenzene and 4-vinylpyridine to acetonitrile at a molar ratio of 1:2-6 and pre-complex at 20-40℃ for 2-8 hours; C2. Add the vinylized nucleus, ethylene glycol dimethacrylate, and 2,2-azobisisobutyronitrile to the system obtained in step C1, wherein the molar ratio of 1,2,3-trichlorobenzene, 4-vinylpyridine, ethylene glycol dimethacrylate, and 2,2-azobisisobutyronitrile is 1:2-6:8-20:0.05-0.20; C3. After purging with nitrogen for 10-30 minutes, polymerize at 55-70℃ for 8-24 hours under nitrogen protection; C4. Elute 3-8 times with an eluent containing methanol and glacial acetic acid in a volume ratio of 9-12:1, and dry at 40-60℃ for 4-10 hours; C5. Obtain the core-shell composite particles with a shell thickness of 5-30 nm.

5. The 1,2,3-trichlorobenzene detection and analysis material as described in claim 4, characterized in that, The anchoring layer and the composite extraction recognition coating are formed through the following steps: D1. Clean the 304 stainless steel wire, titanium wire, quartz fiber or glass fiber substrate with ethanol and deionized water in sequence and then dry it; D2. Add 3-aminopropyltriethoxysilane and tetraethoxysilane to a hydrolysis system consisting of ethanol, deionized water and 25% ammonia, wherein the molar ratio of 3-aminopropyltriethoxysilane to tetraethoxysilane is 1:0.5-4, and the volume ratio of ethanol, deionized water and 25% ammonia is 20-60:1-10:0.1-2, and hydrolyze at 25-45℃ for 0.5-4h. D3. Disperse the core-shell composite particles in the hydrolysis system obtained in step D2 at a concentration of 0.5-20 g / L, and coat them onto the substrate surface by dip coating or stretch coating. D4. Curing at 70-120℃ for 0.5-2h yields the 1,2,3-trichlorobenzene detection and analysis material, the thickness of which is 3-20μm for the composite extraction identification coating.

6. The 1,2,3-trichlorobenzene detection and analysis material as described in claim 1, characterized in that, The vinylized core accounts for 40-80 wt% of the total mass of the core-shell composite particles, the molecularly imprinted polymer shell accounts for 20-60 wt% of the total mass of the core-shell composite particles, and the sum of their mass fractions is 100 wt%. The thickness of the anchoring layer is 50-1000 nm. In the anchoring layer, 3-aminopropyltriethoxysilane and tetraethoxysilane form a Si-O-Si network structure. The Si-O-Si network structure is connected to the substrate surface through Si-O-Si or Si-O-metal covalent bonds. The anchoring layer fixes the core-shell composite particles through physical embedding of the siloxane network.

7. The 1,2,3-trichlorobenzene detection and analysis material as described in claim 1, characterized in that, The diameter of the substrate is 50-300 μm, and the effective coating length of the composite extraction and identification coating on the substrate surface is 5-30 mm.

8. A method for preparing a 1,2,3-trichlorobenzene detection and analysis material as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. 2,4,6-tricarboxymethylphloroglucinol and p-phenylenediamine were reacted under nitrogen protection in a mixed solvent consisting of 1,4-dioxane, 1,3,5-trimethylbenzene and glacial acetic acid to prepare a covalent organic framework core with β-keto-enamine bonds; S2. The β-ketoenamine-linked covalent organic framework core is dispersed in a mixture of ethanol and deionized water and then vinylized with 3-(methacryloyloxy)propyltrimethoxysilane to prepare a vinylized core; S3. 1,2,3-trichlorobenzene and 4-vinylpyridine are pre-complexed in acetonitrile. The vinylized core, ethylene glycol dimethacrylate and 2,2-azobisisobutyronitrile are added to the resulting system. Molecular imprinting polymerization is carried out under nitrogen protection, and the particles are eluted and dried to prepare core-shell composite particles. S4. The substrate is washed and dried sequentially with ethanol and deionized water; 3-aminopropyltriethoxysilane and tetraethoxysilane are added to a hydrolysis system composed of ethanol, deionized water and ammonia in a volume ratio of 20-60:1-10:0.1-2 at a molar ratio of 1:0.5-4, and hydrolyzed and condensed at 25-45℃ for 0.5-4h; the core-shell composite particles are dispersed in the obtained hydrolysis system at 0.5-20g / L, and coated onto the substrate surface by dip coating or stretch coating to form an anchoring layer, thereby fixing the core-shell composite particles to the substrate surface; S5. Curing at 70-120℃ for 0.5-2h yields the 1,2,3-trichlorobenzene detection and analysis material.

9. The preparation method according to claim 8, characterized in that: In step S1, the molar ratio of 2,4,6-tricarboxymethyl phloroglucinol to p-phenylenediamine is 1:1-1.5, the volume ratio of 1,4-dioxane, 1,3,5-trimethylbenzene and glacial acetic acid is 4-8:4-8:0.5-2, the reaction temperature is 110-130℃, and the reaction time is 24-72h. In step S2, the pH of the system is adjusted to 4.5-5.5 with glacial acetic acid, the reaction temperature is 50-75℃, the reaction time is 2-8h, and the grafting amount of 3-(methacryloyloxy)propyltrimethoxysilane is 0.20-0.80mmol / g. In step S3, the molar ratio of 1,2,3-trichlorobenzene, 4-vinylpyridine, ethylene glycol dimethacrylate and 2,2-azobisisobutyronitrile is 1:2-6:8-20:0.05-0.20, the polymerization temperature is 55-70℃, the polymerization time is 8-24h, and the eluent is used to elute 3-8 times with a methanol and glacial acetic acid volume ratio of 9-12:

1. In step S4, the molar ratio of 3-aminopropyltriethoxysilane to tetraethoxysilane is 1:0.5-4, the volume ratio of ethanol, deionized water and 25% ammonia is 20-60:1-10:0.1-2, the hydrolysis temperature is 25-45℃, the hydrolysis time is 0.5-4h, and the core-shell composite particles are fixed on the substrate surface by dip coating or stretch coating, with 1-10 coating times. In step S5, the curing temperature is 70-120℃ and the curing time is 0.5-2h.

10. The preparation method according to claim 9, characterized in that, The substrate is one of 304 stainless steel wire, titanium wire, quartz fiber or glass fiber, and its diameter is 50-300 μm. The effective coating length on the substrate surface is 5-30 mm. The number average particle size of the covalent organic framework core with β-keto-enamine bond obtained in step S1 is 80-250 nm. The shell thickness of the core-shell composite particles obtained in step S3 is 5-30 nm. The content of 1,2,3-trichlorobenzene remaining in the core-shell composite particles after template elution in step S3 is quantitatively determined by gas chromatography using the external standard method. The calculation basis is the total dry weight of the core-shell composite particles after elution, and its value is not higher than 0.5 wt%. The thickness of the composite extraction identification coating of the 1,2,3-trichlorobenzene detection and analysis material obtained in step S5 is 3-20 μm.

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