Resin-based nanocomposite material, and preparation method and application thereof

Abstract

This invention discloses a resin-based nanocomposite material, its preparation method, and its application, belonging to the field of chemical materials technology. First, resin microspheres are prepared by suspension polymerization of methacrylate-based functional monomers with divinylbenzene. After swelling, these microspheres undergo sequential hydrolysis, chloromethylation, and amination treatments to obtain anion exchange resin microspheres with a special pore structure and a positive charge. These microspheres are then blended with chloroauric acid solution and reduced with sodium citrate, allowing gold nanoparticles to grow in situ within the special pore structure of the resin microspheres, resulting in a resin-based nanocomposite material that can be used to enhance Raman signals. The composite material in this invention adsorbs metal nanoparticles within the special pore structure of the resin microspheres, minimizing the impact on the micropores of the resin microspheres used for mass transfer and adsorption processes. The spatial confinement effectively enriches the analyte, enabling accurate identification and quantification of highly polar, weakly Raman-signaling, and volatile substances such as TFA.

Description

Technical Field

[0001] This invention belongs to the field of chemical materials technology, specifically relating to a resin-based nanocomposite material, its preparation method, and its application. Background Technology

[0002] Per- and polyfluoroalkyl substances (PFAS) are a class of synthetic chemicals with high stability, bioaccumulation, and toxicity. With the strict restrictions on the use of long-chain and some short-chain PFAS, ultra-short-chain PFAS are emerging as alternatives, leading to a rapid increase in their environmental concentrations. Among them, trifluoroacetic acid (TFA) shows orders-of-magnitude concentrations in various environmental media, and is the most concentrated PFAS component in landfill leachate and human serum in China, and has been proven to have reproductive and hepatotoxic effects. Developing detection methods for TFA in environmental media is a crucial step in improving its regulatory system.

[0003] Surface-enhanced Raman spectroscopy (SERS) is a spectroscopic analysis technique based on the Raman scattering effect. It typically uses specific metal nanostructures (such as gold or silver) as the SERS substrate material. When an excitation source irradiates the surface of the metal nanostructure, it induces localized surface plasmon resonance (LSPR), generating a strong localized electromagnetic field. This enhancement of the localized electromagnetic field significantly increases the Raman scattering cross section of the analyte adsorbed on the surface of the metal nanostructure, resulting in a significant enhancement of the Raman signal (electromagnetic enhancement effect). Furthermore, when molecules adsorb onto the surface of the metal nanostructure, their electronic energy levels couple with those of the metal. This coupling causes changes in the polarizability of the molecule, which also alters the Raman scattering cross section, affecting the Raman signal (chemical enhancement effect). These Raman signals provide rich information on chemical bond vibrations and are considered the "molecular fingerprint" of molecules, thus enabling the identification and quantification of target analytes. Traditional SERS substrate materials often involve depositing metal nanoparticles onto silicon wafers to create a flat substrate, then adding the analyte solution, allowing it to dry, and finally performing the detection. However, TFAs are volatile, have low polarizability of carbon-fluorine bonds in their molecules, and inherently have very small Raman scattering cross sections and weak Raman signals, making them difficult to accurately identify and quantify. This underscores the importance of enriching TFAs sufficiently around metal nanoparticles (hotspot regions), i.e., compensating for their inherent weak Raman signals and volatility by increasing the concentration of TFAs in the hotspot regions.

[0004] Hu et al. used a solution impregnation method to achieve in-situ generation of gold nanoparticles (AuNPs) within the metal-organic framework MIL-101 matrix, obtaining AuNPs / MIL-101 nanocomposites. Combining the localized surface plasmon resonance (SERS) properties of AuNPs with the porous structure and high specific surface area of ​​MIL-101, the analytes were concentrated near the electromagnetic field of the active metal surface, making it a highly sensitive SERS substrate material. However, the metal-organic framework MIL-101 is a crystalline coordination polymer formed by the coordination of metal ions and organic ligands. Due to the low strength of the coordination bonds, the metal framework structure is relatively fragile, limiting the amount of AuNPs it can support. Experimental results showed that when using a 0.12% chloroauric acid solution to prepare the AuNPs / MIL-101 nanocomposite, the octahedral crystal structure of MIL-101 underwent significant deformation, and some AuNPs grew to the outer surface of MIL-101, failing to successfully embed within it. Meanwhile, by measuring the specific surface area of ​​pure MIL-101 and the prepared AuNPs / MIL-101, it was found that the specific surface area of ​​MIL-101 before and after loading AuNPs differed by 949 m². 2 / g indicates that the pore portion of MIL-101 is occupied by randomly grown AuNPs in situ, which may affect the subsequent mass transfer (transport of substances within the composite molecules or between the composite and the external environment) and adsorption processes of MIL-101-based composites, thus affecting the enrichment of analytes.

[0005] In summary, there is an urgent need to develop a novel SERS substrate material to fully enrich volatile substances such as TFA with weak Raman signals in the hot spot region around metal nanoparticles, so as to achieve accurate identification and quantification. Summary of the Invention

[0006] 1. The problem to be solved To address the issue that traditional planar SERS substrates and novel AuNPs / MIL-101 nanocomposites lack sufficient enrichment capacity for analytes, especially volatile analytes (TFAs), potentially affecting the sensitivity and accuracy of detection, this invention provides a resin microsphere-based nanocomposite material. By swelling the prepared polyacrylate resin microspheres and then sequentially undergoing ester hydrolysis, chloromethylation, and amination treatments, more gold nanoparticles grow in situ within the specialized pore structure of the resin microspheres, reducing encroachment on the fundamental pore structure used for mass transfer and adsorption processes. (Tests show that the change in specific surface area of ​​the resin microspheres before and after loading with gold nanoparticles is ≤100 m²). 2(g); Furthermore, the ion exchange groups (positively charged) modified by the resin microspheres fully enrich TFA (negatively charged) analytes in the hot spot region around the gold nanoparticles, thereby enhancing the detection signal intensity of the analytes. Experiments have shown that the limit of quantitation for TFA in the resin-based nanocomposite material of this invention is as low as 1.93 μg / L.

[0007] 2. Technical Solution To solve the above problems, the technical solution adopted by the present invention is as follows: This invention provides a resin-based nanocomposite material, which uses polyacrylate resin microspheres as a carrier. The polyacrylate resin microspheres are anion exchange resin microspheres with a special pore structure after being subjected to swelling, ester hydrolysis, chloromethylation and amination treatments in sequence. Gold nanoparticles are grown in situ within this special pore structure. It should be noted that this special pore structure is a "ink bottle-shaped" mesoporous pore structure formed by the shedding of ester group fragments after ester hydrolysis treatment. Its internal space is relatively large (bottle body) and the pore opening is relatively narrow (bottleneck), which is very suitable for the in-situ growth of gold nanoparticles (10~30 nm).

[0008] Furthermore, the average particle size of the above-mentioned polyacrylate resin microspheres is 30~50 µm, and the specific surface area is 300~500 m². 2 / g, with a total exchange capacity of 1~5 mmol / g, which is determined according to GB / T5760-2025 based on dried polyacrylate resin microspheres; The D50 particle size of the above gold nanoparticles is 10~30 nm, and the loading amount on polyacrylate resin microspheres is 200~400 mg / g. The specific surface area change of the above polyacrylate resin microspheres before and after loading gold nanoparticles is ≤100 m². 2 / g.

[0009] This invention also provides a method for preparing a resin-based nanocomposite material, the method comprising the following steps: S1. Preparation of resin microspheres: Divinylbenzene and methacrylate-based functional monomers are mixed as the oil phase; gelatin, sodium chloride, and trisodium phosphate are dissolved in water as the aqueous phase; the oil phase and aqueous phase are mixed and subjected to suspension polymerization to obtain resin microspheres; S2, Ester Hydrolysis: The resin microspheres from S1 are cleaned, soaked in a swelling agent to swell, and then the resin microspheres are removed. Then, a 20-30% (w / w) NaOH aqueous solution is added for hydrolysis. After hydrolysis, the resin microspheres are removed, washed, and dried to obtain ester-hydrolyzed resin microspheres. It should be noted that traditional resins often use small-molecule organic compounds as pore-forming agents, resulting in microporous structures of 1-10 nm, which is not conducive to the growth of gold nanoparticles (10-30 nm). This invention utilizes the characteristic that methacrylate-based functional monomers can be hydrolyzed under alkaline conditions, and uses the principle of "sacrificial fragments" to create pores, yielding a special "ink bottle-like" pore structure. This invention is demonstrated by observing the nitrogen adsorption / desorption isotherms of the nanocomposite material (see attached diagram). Figure 1 It exhibits Type IV adsorption and is accompanied by a distinct desorption hysteresis loop, a typical characteristic of mesoporous materials. The hysteresis loop corresponds to Type H2, representing an "ink bottle-shaped" mesoporous channel structure (the classification of adsorption isotherms and hysteresis loops follows the International Union of Pure and Applied Chemistry (IUPAC) classification system). Compared to traditional microporous channel structures (1-10 nm), its internal space is larger (bottle body) and the pore opening is narrower (bottleneck), making it more suitable for the in-situ growth of gold nanoparticles (10-30 nm). This prevents excessive encroachment and blockage of the basic pore structure formed during the S1 polymerization stage for mass transfer and adsorption. Testing showed that the specific surface area change of the resin microspheres in this invention before and after loading with gold nanoparticles was controlled within 100 m². 2 Within a certain range (e.g.), it was further confirmed that the gold nanoparticles did not excessively invade or block the basic pores of the resin microspheres, but instead grew more within a special pore structure with larger and more suitable space. This invention utilizes the aforementioned special pore structure to achieve a large loading of gold nanoparticles (up to 322 mg / g in Example 1), laying a good structural foundation for the sufficient enrichment of analytes. S3. Modification Treatment: The ester-hydrolyzed resin microspheres in S2 were modified by chloromethylation, followed by amination treatment with an amination reagent to obtain modified resin microspheres. It should be noted that, after modification treatment, on the one hand, the ion exchange groups after amination can attract more chloroauric acid into the pores of the resin microspheres, avoiding the reduction of gold nanoparticles on the surface of the resin microspheres, increasing the loading of gold nanoparticles in the pores of the resin microspheres, and at the same time preventing the already loaded gold nanoparticles from falling out of the pores; on the other hand, the amination resin microspheres are positively charged, which can effectively enrich the negatively charged TFA, thereby reducing sample loss caused by volatilization by binding TFA within the pore structure. S4. In-situ reduction of gold nanoparticles: The modified resin microspheres in S3 were soaked and swollen in a swelling agent, and then transferred to a HAuCl4 solution with pH 1~4 and stirred continuously; then the HAuCl4 solution was heated to a vigorous boil, and sodium citrate solution was immediately added. Stirring was continued at the boiling temperature. After the reaction was completed, the resin-based nanocomposite material was obtained by centrifugation, washing and drying.

[0010] Furthermore, the functional monomers of the above-mentioned methacrylate system include one or more of stearate methacrylate, lauryl methacrylate, and benzyl methacrylate.

[0011] Furthermore, the functional monomers of the above-mentioned methacrylate system are stearate methacrylate and benzyl methacrylate.

[0012] Furthermore, the mass ratio of divinylbenzene: stearate methacrylate: benzyl methacrylate is 1:(0.1~1):(0.1~1).

[0013] Furthermore, the functional monomers of the above-mentioned methacrylate system are lauryl methacrylate and benzyl methacrylate.

[0014] Furthermore, the mass ratio of divinylbenzene: lauryl methacrylate: benzyl methacrylate is 1:(0.1~1):(0.1~3).

[0015] Furthermore, the mass ratio of gelatin:sodium chloride:trisodium phosphate:ultrapure water is 1:(0.5~1):(2~3):(86~88).

[0016] Furthermore, the oil phase and the water phase are mixed at a mass ratio of 1:(1~1.1).

[0017] Furthermore, the oil phase and the water phase are mixed at a mass ratio of 1:1.

[0018] Furthermore, the above suspension polymerization reaction was carried out at 95~110℃ and 1000~2000 rpm for 4~12 h.

[0019] Furthermore, the swelling agent in S2 above includes one or more of methanol, ethanol, and dichloroethane.

[0020] Furthermore, the swelling agent in S2 above is methanol and ethanol, with a volume ratio of 1:(0.5~1).

[0021] Furthermore, the above-mentioned S2 is soaked and swollen at 20~40℃ for 12~14 h.

[0022] Furthermore, the above hydrolysis was carried out at 70~90℃ for 12~24 h.

[0023] Further, the above-mentioned chloromethylation modification includes: mixing the resin microspheres with ester group hydrolysis in S2 with chloromethyl ether in a three-necked flask, then adding anhydrous FeCl3, then adding sulfuric acid solution dropwise, reacting at room temperature for 1-2 h, and then heating to 40-50℃ for 22-26 h.

[0024] Furthermore, the amination reagents mentioned above include one or more of ethylenediamine, diethylamine, piperazine, and dimethylamine.

[0025] Further, the above amination treatment includes: adding chloromethylated resin microspheres and amination reagent to a three-necked round-bottom flask, refluxing the suspension at 70-80℃ and 400-600 rpm for 22-26 h, cooling, washing the product until the pH of the washing solution is around 6-7, and collecting the product.

[0026] Furthermore, the swelling agent in S4 above includes one or more of methanol, ethanol, and dichloroethane.

[0027] Furthermore, the swelling agent in S4 above is ethanol.

[0028] Furthermore, the mass percentage concentration of the above HAuCl4 solution is 0.4~0.6% (w / v).

[0029] Furthermore, the above-mentioned HAuCl4 solution was continuously stirred at 50-60°C for 5-7 h.

[0030] Furthermore, the initial mass percentage concentration of the sodium citrate solution is 20-25% (w / v), and it is added at 1-3‰ (v / v) of the volume of the HAuCl4 solution.

[0031] Furthermore, the stirring time at the above boiling temperature is continued for 12 to 24 hours.

[0032] The present invention also provides a resin-based nanocomposite material prepared by the above preparation method.

[0033] This invention also provides the application of the above-mentioned resin-based nanocomposite material in the detection of volatile substances.

[0034] The present invention also provides the application of the above-mentioned resin-based nanocomposite material in detecting substances with inherently weak Raman signals.

[0035] The present invention also provides the application of the above-mentioned resin-based nanocomposite material in the detection of volatile substances and substances with inherently weak Raman signals.

[0036] Furthermore, the above-mentioned substances include TFA; it should be noted that the nanocomposite material in this invention exhibits good recognition and quantitative detection effects for TFA, with a quantification limit as low as 1.93 μg / L.

[0037] 3. Beneficial effects Compared with the prior art, the advantages of this invention are as follows: (1) This invention provides a resin-based nanocomposite material, its preparation method, and its application. Utilizing the hydrolytic property of methacrylate-based functional monomers under alkaline conditions, the prepared resin microspheres are constructed using a "sacrificial fragment method" to achieve a special "ink bottle-shaped" pore structure. The large internal pores and narrow openings facilitate the in-situ growth of gold nanoparticles. Furthermore, the "sacrificial fragment method" requires hydrolyzing and eluting the ester-based fragments from the already cured resin framework, and some larger fragments are difficult to detach using ordinary hydrolysis methods. To increase the loading capacity of gold nanoparticles, this invention adds a swelling step before hydrolysis to promote the detachment of ester-based fragments, ensuring the effective formation of more special pore structures capable of accommodating gold nanoparticles. By constructing these special pore structures suitable for gold nanoparticle growth, this invention increases the loading capacity of gold nanoparticles and reduces the encroachment and blockage of the basic pore structures inside the resin microspheres used for mass transfer and adsorption processes by gold nanoparticles (the change in the specific surface area of ​​the resin microspheres before and after loading gold nanoparticles is controlled within 100 m²). 2 (within / g) to further ensure sufficient enrichment of the analyte.

[0038] (2) The present invention provides a resin-based nanocomposite material, its preparation method and application. By amination modification of resin microspheres, chloroauric acid particles are adsorbed into the pores of the resin microspheres and reduced in situ using the electrostatic adsorption of amine groups. This effectively avoids the detachment of the reduced product gold nanoparticles and further increases the loading of gold nanoparticles. At the same time, the amination resin microspheres can also effectively enrich negatively charged TFA through electrostatic adsorption. By binding TFA within the pore structure, sample loss caused by the volatilization process is reduced, and inaccurate qualitative and quantitative analysis due to the uncontrolled volatilization of TFA is avoided.

[0039] (3) The resin-based nanocomposite material, its preparation method, and its application provided by this invention comprehensively consider both the material's structural characteristics (special pore structure) and adsorption characteristics (modification treatment), ensuring efficient loading of gold nanoparticles and sufficient enrichment of analytes. This makes it highly suitable for the identification and quantification of volatile substances and / or substances with inherently weak Raman signals. Verification has shown that the resin-based nanocomposite material in this invention has a TFA detection limit as low as 1.93 μg / L, demonstrating promising application prospects. Attached Figure Description

[0040] Figure 1 This is a nitrogen adsorption / desorption isotherm diagram of the modified resin microspheres in Example 1 of the present invention.

[0041] Figure 2 This is a full SEM image of the nanocomposite material A1 in Example 1 of the present invention.

[0042] Figure 3 This is a partial TME image of the nanocomposite material A1 in Example 1 of the present invention. Detailed Implementation

[0043] The present invention will be further described below with reference to specific embodiments.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0045] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0046] As used herein, the term “about” is used to provide for the flexibility and imprecision associated with a given term, measure, or value. Those skilled in the art can readily determine the degree of flexibility for a particular variable. Concentration, amount, and other numerical data may be presented in range format herein. It should be understood that such range format is used solely for convenience and brevity and should be flexibly interpreted to include not only the values ​​explicitly stated as the limits of the range, but also all individual values ​​or subranges encompassed within the range, as if each value and subrange were explicitly stated. For example, a range of values ​​from about 1 to about 4.5 should be interpreted to include not only the explicitly stated limits of 1 to 4.5, but also individual numbers (such as 2, 3, 4) and subranges (such as 1 to 3, 2 to 4, etc.). The same principle applies to ranges that describe only a single value, such as "less than about 4.5," which should be interpreted to include all the values ​​and ranges described above. Furthermore, this interpretation should apply regardless of the breadth of the range or characteristic described.

[0047] The reagents used in the embodiments of this invention are as follows: Divinylbenzene: 80% isomer mixture, containing 1000 ppm 4-tert-butylcatechol; Alfa Aesar; Stearic acid stearate: A mixture of stearic acid and hexadecyl methacrylate, containing 50 ppm MEHQ as a stabilizer; Aladdin; Benzyl methacrylate: ≥98%, containing 50 ppm MEHQ as a stabilizer; Aladdin; Lauryl methacrylate: ≥96%, containing 50 ppm MEHQ as a stabilizer; Aladdin; Gelatin: CP; Shanghai Husheng Co., Ltd. Sodium chloride: AR; Nanjing Chemical Reagent Co., Ltd.; Trisodium phosphate: AR; Nanjing Chemical Reagent Co., Ltd.; Methanol: AR; Nanjing Chemical Reagent Co., Ltd.; Ethanol: AR; Nanjing Chemical Reagent Co., Ltd.; Sodium hydroxide: AR; Nanjing Chemical Reagent Co., Ltd.; Chloromethyl ether: ≥97%; Aladdin; Ethylenediamine: ≥98%; Aladdin; Tetrachloroalloyic acid (HAuCl4): ≥99.9% metals basis; Aladdin; Sodium citrate: ≥98%; Aladdin.

[0048] The instruments used in the embodiments of this invention are as follows: Transmission electron microscope: Hitachi HT7800; Scanning electron microscope: Hitachi S 3400N; Nitrogen adsorption-desorption experimental apparatus: AUTOSORB IQ.

[0049] Example 1 This embodiment provides a method for preparing a resin-based nanocomposite material and the prepared resin-based nanocomposite material A1.

[0050] The preparation method steps are as follows: S1. Preparation of resin microspheres 75 g of divinylbenzene, 50 g of stearate methacrylate and 50 g of benzyl methacrylate were mixed as the oil phase; 2 g of gelatin, 1 g of sodium chloride and 4 g of trisodium phosphate were dispersed in 175 mL of ultrapure water (approximately 175 g at room temperature and pressure) as the aqueous phase; the above oil phase and aqueous phase were mixed and subjected to suspension polymerization at 95 °C and 2000 rpm for 8 h to obtain resin microspheres; S2, ester hydrolysis The resin microspheres in S1 were washed with methanol, dried, and then placed in a swelling agent of 2 times their mass (methanol:ethanol = 1:1 (v:v)) at 30°C for 12 h to swell. The resin microspheres were then removed and transferred to a 25% NaOH aqueous solution of 5 times their mass and hydrolyzed at 90°C with stirring for 24 h. After hydrolysis, the resin microspheres were removed, washed with ultrapure water and methanol until neutral, and dried to obtain ester-hydrolyzed resin microspheres. S3, Modification Treatment The resin microspheres with hydrolyzed ester groups in S2 were modified by chloromethylation to obtain active chlorine groups; then, they were amination treated with ethylenediamine amination reagent to obtain modified resin microspheres (i.e., anion exchange resin microspheres). Specifically, the chloromethylation modification includes: mixing 30 g of ester-hydrolyzed resin microspheres with 60 mL of chloromethyl ether in a three-necked flask; after 2 h, adding 30 g of anhydrous FeCl3, then adding 15 mL of sulfuric acid solution dropwise to the reaction system, reacting at room temperature for 1 h, and then heating to 47.5 °C to continue the reaction for 24 h to obtain chloromethylated resin microspheres; Amination treatment: In a three-necked flask (equipped with a stir bar and a reflux condenser), 20 g of chloromethylated resin microspheres were mixed with 200 mL of ethylenediamine and refluxed at 70 °C and 400 rpm for 24 h. After cooling, the product was washed four times with ethanol and deionized water until the pH of the washing solution was close to neutral (around pH 6-7). The product was collected by extraction to obtain the modified resin microspheres. S4, In-situ reduction of gold nanoparticles The modified resin microspheres from S3 were placed in a swelling agent (ethanol) of 2 times their mass and soaked and swollen at room temperature for 2 h. Then, the resin microspheres were transferred to 150 mL of HAuCl4 solution with pH 2 and a mass percentage concentration of 0.5% (w / v) and stirred continuously at 50 °C for 6 h. The HAuCl4 solution was then heated to a vigorous boil, and a sodium citrate solution with a mass percentage concentration of 25% (w / v) was immediately added at a volume of 1‰ of the HAuCl4 solution volume. The mixture was stirred continuously at the boiling temperature for 12 h. After the reaction was completed, the mixture was centrifuged (3000 rpm, 3 min), washed (rinsed with ethanol and deionized water), and vacuum dried to obtain resin-based nanocomposite material A1 (i.e., anion exchange resin microspheres loaded with gold nanoparticles).

[0051] In addition, the structural characteristics of the resin microspheres at different stages of the above preparation process were characterized by nitrogen adsorption / desorption experiments (this part of the work was commissioned to Science Compass). At the same time, the morphology of the finally prepared resin-based nanocomposite material A1 was characterized by electron microscopy.

[0052] Table 1. Specific surface area, pore volume, and pore size of resin microspheres at different stages

[0053] Table 1 shows the structural characteristics of resin microspheres at different stages. The nitrogen adsorption / desorption isotherms of the resin microspheres after amination (modification) are shown below. Figure 1As shown, the isotherm exhibits type IV characteristics, accompanied by a distinct desorption hysteresis loop. According to the International Union of Pure and Applied Chemistry (IUPAC) classification of adsorption isotherms and hysteresis loops, this pore structure is defined as an "ink bottle-like" mesoporous channel structure (i.e., the special channel structure in this invention). The average particle size of the nanocomposite material Al was measured to be 42 µm, and the specific surface area was 486 m². 2 / g, the total exchange capacity was 1.2 mmol / g (dry resin, determined according to GB / T 5760-2025), the D50 particle size of the gold nanoparticles was 30 nm, and the loading amount on the resin microspheres was 322 mg / g (determined by weighing method, i.e., the mass of the dried resin microspheres before and after loading gold nanoparticles).

[0054] Figures 2-3 The images shown are a full SEM image and a partial TEM image of the nanocomposite material A1. The SEM images reveal that the resin is spherical with a rough surface, which facilitates mass transfer. TEM characterization of the resin microspheres' edges shows that the gold nanoparticles are uniform in size and successfully loaded into the internal porous structure of the resin microspheres.

[0055] Example 2 This embodiment provides a method for preparing resin-based nanocomposites and the prepared resin-based nanocomposites A2.

[0056] The preparation method differs from Example 1 only in that, in S1 of this method, 75 g of divinylbenzene, 50 g of lauryl methacrylate and 100 g of benzyl methacrylate are mixed as the oil phase; 2.6 g of gelatin, 1.3 g of sodium chloride and 5.2 g of trisodium phosphate are dispersed in 225 mL (about 225 g) of ultrapure water as the aqueous phase. Other operations are the same as in Example 1, and finally resin-based nanocomposite material A2 is obtained.

[0057] Similar to Example 1, the structural characteristics of the resin microspheres at different stages of the preparation process were characterized, and the ion exchange capacity and gold nanoparticle ion loading were measured.

[0058] Table 2. Specific surface area, pore volume, and pore size of resin microspheres at different stages

[0059] Based on Table 2, the average particle size of the resin-based nanocomposite A2 was measured to be 39 µm, and the specific surface area was 366 m². 2 The gold nanoparticles have a total exchange capacity of 1.31 mmol / g and a D50 particle size of 26 nm. The loading of gold nanoparticles on the resin is 294 mg / g.

[0060] Comparative Example 1 This comparative example provides a method for preparing resin-based nanocomposites and the prepared resin-based nanocomposites B1.

[0061] The preparation method differs from Example 1 only in that, in S1 of this method, 75 g of divinylbenzene, 100 g of lauryl methacrylate and 50 g of benzyl methacrylate are mixed as the oil phase; 2.6 g of gelatin, 1.3 g of sodium chloride and 5.2 g of trisodium phosphate are dispersed in 225 mL (about 225 g) of ultrapure water as the aqueous phase. Other operations are the same as in Example 1, and finally resin-based nanocomposite material B1 is obtained.

[0062] Similar to Example 1, the structural characteristics of the resin microspheres at different stages of the preparation process were characterized, and the ion exchange capacity and gold nanoparticle ion loading were measured.

[0063] Table 3. Specific surface area, pore volume, and pore size of resin microspheres at different stages

[0064] Based on Table 3, the average particle size of the resin-based nanocomposite B1 was measured to be 110 µm, and the specific surface area was 166 m². 2 The total exchange capacity is 0.98 mmol / g, the D50 particle size of the gold nanoparticles is 80 nm, and the loading of gold nanoparticles on the resin is 84.2 mg / g.

[0065] Comparative Example 2 This comparative example provides a method for preparing resin-based nanocomposites and the prepared resin-based nanocomposites B2.

[0066] The preparation method differs from Example 1 only in that, in S1 of this method, 75 g of divinylbenzene is selected as the oil phase, and 0.86 g of gelatin, 0.43 g of sodium chloride and 1.71 g of trisodium phosphate are dispersed in 75 mL (about 75 g) of ultrapure water as the aqueous phase. Other operations are the same as in Example 1, and finally resin-based nanocomposite material B2 is obtained.

[0067] Similar to Example 1, the structural characteristics of the resin microspheres at different stages of the preparation process were characterized, and the ion exchange capacity and gold nanoparticle ion loading were measured.

[0068] Table 4. Specific surface area, pore volume, and pore size of resin microspheres at different stages

[0069] Based on Table 4, the average particle size of the resin-based nanocomposite B2 was measured to be approximately 91 µm, and the specific surface area was 295 m². 2 The total exchange capacity was 0.09 mmol / g, and the loading of gold nanoparticles on the resin was 0.04 mg / g.

[0070] Comparative Example 3 This comparative example provides a method for preparing resin-based nanocomposites and the prepared resin-based nanocomposites B3.

[0071] The preparation method differs from Example 1 only in that, in S1 of this method, 1 g of gelatin, 10 g of sodium chloride and 10 g of trisodium phosphate are dispersed in 175 mL of ultrapure water as the aqueous phase. Other operations are the same as in Example 1, and finally, resin-based nanocomposite material B3 is obtained.

[0072] Similar to Example 1, the structural characteristics of the resin microspheres at different stages of the preparation process were characterized, and the ion exchange capacity and gold nanoparticle ion loading were measured.

[0073] Table 5. Specific surface area, pore volume, and pore size of resin microspheres at different stages

[0074] Based on Table 5, the average particle size of the resin-based nanocomposite B3 was measured to be approximately 80 µm, and the specific surface area was 80 m². 2 The total exchange capacity was 0.67 mmol / g, and the loading of gold nanoparticles on the resin was 0.84 mg / g.

[0075] Comparative Example 4 This comparative example provides a method for preparing resin-based nanocomposites and the prepared resin-based nanocomposites B4.

[0076] The preparation method differs from Example 1 only in that the suspension polymerization reaction in S1 of this method is carried out at 600 rpm, while other operations are the same as in Example 1, and finally resin-based nanocomposite material B4 is obtained.

[0077] Similar to Example 1, the structural characteristics of the resin microspheres at different stages of the preparation process were characterized, and the ion exchange capacity and gold nanoparticle ion loading were measured.

[0078] Table 6. Specific surface area, pore volume, and pore size of resin microspheres at different stages

[0079] Based on Table 6, the average particle size of the resin-based nanocomposite B4 was measured to be 100 µm, and the specific surface area was 75 m². 2 The total exchange capacity is 0.78 mmol / g, the D50 particle size of the gold nanoparticles is 69 nm, and the loading of gold nanoparticles on the resin is 62 mg / g.

[0080] Comparative Example 5 This comparative example provides a method for preparing resin-based nanocomposites and the prepared resin-based nanocomposites B5.

[0081] The preparation method differs from Example 1 only in that, in this method, before the hydrolysis operation in S2, the resin microspheres are not pre-soaked and swollen with a swelling agent, but are directly subjected to subsequent hydrolysis. Other operations are the same as in Example 1, and finally, resin-based nanocomposite material B5 is obtained.

[0082] Similar to Example 1, the structural characteristics of the resin microspheres at different stages of the preparation process were characterized, and the ion exchange capacity and gold nanoparticle ion loading were measured.

[0083] Table 7. Specific surface area, pore volume, and pore size of resin microspheres at different stages

[0084] Based on Table 7, the average particle size of the resin-based nanocomposite B5 was measured to be 400 µm, and the specific surface area was 79 m². 2 The total exchange capacity was 0.28 mmol / g, and the loading of gold nanoparticles on the resin was 6.87 mg / g.

[0085] Comparative Example 6 This comparative example provides a method for preparing resin-based nanocomposites and the prepared resin-based nanocomposites B6.

[0086] The preparation method differs from Example 1 only in that the mass percentage concentration of sodium citrate solution added in S4 of this method is 15% (w / v). Other operations are the same as in Example 1, and the resin-based nanocomposite material B6 is finally obtained.

[0087] Similar to Example 1, the structural characteristics of the resin microspheres at different stages of the preparation process were characterized, and the ion exchange capacity and gold nanoparticle ion loading were measured.

[0088] Table 8. Specific surface area, pore volume and pore size of resin microspheres at different stages

[0089] Based on Table 8, the average particle size of the resin-based nanocomposite B6 was measured to be 451 µm, and the specific surface area was 560 m². 2 The total exchange capacity is 1.24 mmol / g, the D50 particle size of the gold nanoparticles is 96 nm, and the loading of gold nanoparticles on the resin is 94.6 mg / g.

[0090] Example 3 This embodiment provides the detection performance of resin-based nanocomposites for TFA.

[0091] Specifically, the resin-based nanocomposites A1 and A2 in Examples 1-2 and the resin-based nanocomposites B1-B6 in Comparative Examples 1-6 were subjected to the determination of the limit of quantitation for TFA using the direct dilution method, as follows: A series of TFA standard working solutions of 0.1, 0.5, 1.0, 5.0, 10.0, 50.0, 100.0, and 500.0 μg / L were prepared for use. 10.0 mg of the resin-based nanocomposite material was weighed and placed in a 2 mL centrifuge tube, and 1.0 mL of a TFA standard solution of a specific concentration was added. The centrifuge tube was tightly capped and placed in a constant-temperature shaker at 25℃ and 200 rpm for 30 min for adsorption. After adsorption was complete, the centrifuge tube was centrifuged at 8000 rpm for 5 min, the supernatant was discarded, the bottom precipitate was collected, and transferred to a clean silicon wafer. The silicon wafer was placed on the stage of a Raman spectrometer, and the spectrum was acquired under a 785 nm laser.

[0092] Table 9. Limits of Quantitation for TFA Detection of Different Resin-Based Nanocomposites

[0093] It can be seen that resin-based nanocomposite A1 can achieve a TFA detection of 1.93 μg / L, with a linear range of 0.1~100 μg / L and an RSD (relative standard deviation) stability of 4.67% within cycles. Resin-based nanocomposite A2 can achieve a TFA detection of 2.55 μg / L, with a linear range of 0.1~100 μg / L and an RSD stability of 6.41% within cycles. For resin-based nanocomposite B1, after increasing the amount of lauryl methacrylate in the oil phase (improper oil phase ratio), the obtained resin microspheres have an excessively large particle size (110 μm), resulting in a decrease in specific surface area and a significant reduction in gold nanoparticle loading (84.2 mg / g). Furthermore, the particle size is too large (80 nm), leading to a reduction in hot spots within composite B1, a significant decrease in SERS enhancement effect, and a TFA quantification limit as high as 530.6 μg / L. For resin-based nanocomposite B2, without the methacrylate functional monomer, no special pore structure was formed; the resin pores were mainly micropores, unsuitable for in-situ growth of gold nanoparticles. The loading was only 0.04 mg / g, making TFA undetectable. For resin-based nanocomposite B3, improper aqueous phase ratio also prevented quantitative detection of TFA, indicating that the ratio of gelatin, sodium chloride, and trisodium phosphate has a significant impact on resin spheroidization and pore structure formation. Deviating from the optimal ratio in this invention leads to uneven resin microsphere size and a decrease in specific surface area (80 μm). 2The gold nanoparticle loading was low (0.84 mg / g). For the resin-based nanocomposite B4, the excessively slow stirring speed during the suspension polymerization reaction resulted in excessively large resin microsphere particle size (100 μm) and low specific surface area (75 m² / g). 2 The gold nanoparticle loading was only 62 mg / g, and the TFA quantification limit was as high as 692.0 μg / L. For the resin-based nanocomposite B5, direct hydrolysis without swelling resulted in the inability to quantitatively detect TFA, indicating that swelling before hydrolysis is a key step in the "sacrificial fragment method" to create pores. Direct hydrolysis without swelling makes it difficult for the ester-based fragments to fully detach, and the special pore structure is not effectively formed, resulting in a specific surface area of ​​only 79 μg / L. 2 The gold nanoparticle loading was extremely low (6.87 mg / g). For the resin-based nanocomposite B6 (sodium citrate concentration too low), the TFA quantification limit was 66.0 μg / L, which, although an improvement over composites B1-B5, was still much higher than composites A1 and A2. The reason for this may be that the low sodium citrate concentration (15%) led to insufficient reduction of the gold nanoparticles, resulting in larger particle sizes (96 nm) and uneven distribution, ultimately limiting the SERS enhancement effect.

Claims

1. A resin-based nanocomposite material, characterized in that, The material uses polyacrylate resin microspheres as a carrier, and the polyacrylate resin microspheres are anion exchange resin microspheres with a porous structure after being successively subjected to swelling, ester hydrolysis, chloromethylation and amination treatment. Gold nanoparticles are grown in situ within the pore structure. The polyacrylate resin microspheres have an average particle size of 30-50 µm and a specific surface area of ​​300-500 m². 2 / g, with a total exchange capacity of 1~5 mmol / g; The gold nanoparticles have a D50 size of 10-30 nm and a loading amount of 200-400 mg / g on the polyacrylate resin microspheres. The specific surface area of ​​the polyacrylate resin microspheres before and after loading the gold nanoparticles is ≤100 m². 2 / g.

2. The method for preparing a resin-based nanocomposite material according to claim 1, characterized in that, The method includes the following steps: S1. Preparation of resin microspheres: Divinylbenzene and methacrylate-based functional monomers are mixed as the oil phase; gelatin, sodium chloride, and trisodium phosphate are dissolved in ultrapure water as the aqueous phase; the oil phase and aqueous phase are mixed and subjected to suspension polymerization to obtain resin microspheres; S2, Ester hydrolysis: Clean the resin microspheres in S1, soak them in a swelling agent to swell, and take out the resin microspheres; then add 20~30% NaOH aqueous solution by mass to hydrolyze them. After hydrolysis is completed, take out the resin microspheres, wash and dry them to obtain ester hydrolyzed resin microspheres. S3. Modification treatment: The resin microspheres with hydrolyzed ester groups in S2 are modified by chloromethylation, and then subjected to amination treatment with an amination reagent to obtain modified resin microspheres. S4. In-situ reduction of gold nanoparticles: The modified resin microspheres in S3 were soaked and swollen in a swelling agent, and then transferred to a HAuCl4 solution with pH 1~4 and stirred continuously; then the HAuCl4 solution was heated to a vigorous boil, and sodium citrate solution was immediately added. Stirring was continued at the boiling temperature. After the reaction was completed, the resin-based nanocomposite material was obtained by centrifugation, washing and drying.

3. The preparation method according to claim 2, characterized in that, The functional monomers of the methacrylate system include one or more of stearate methacrylate, lauryl methacrylate, and benzyl methacrylate; and / or The swelling agent in S2 includes one or more of methanol, ethanol, and dichloroethane; and / or The amination agent includes one or more of ethylenediamine, diethylamine, piperazine, and dimethylamine; and / or The swelling agent in S4 includes one or more of methanol, ethanol, and dichloroethane.

4. The preparation method according to claim 3, characterized in that, The functional monomers of the methacrylate system are stearate methacrylate and benzyl methacrylate, wherein the mass ratio of divinylbenzene:stearate methacrylate:benzylate methacrylate is 1:(0.1~1):(0.1~1); or the functional monomers of the methacrylate system are lauryl methacrylate and benzyl methacrylate, wherein the mass ratio of divinylbenzene:lauryl methacrylate:benzylate methacrylate is 1:(0.1~1):(0.1~3); and / or The swelling agent in S2 is methanol and ethanol in a volume ratio of 1:(0.5~1); and / or The swelling agent in S4 is ethanol.

5. The preparation method according to any one of claims 2-4, characterized in that, The mass ratio of gelatin:sodium chloride:trisodium phosphate:ultrapure water is 1:(0.5~1):(2~3):(86~88); and / or The oil phase and water phase are mixed at a mass ratio of 1:(1~1.1).

6. The preparation method according to claim 5, characterized in that, The suspension polymerization reaction is carried out at 95-110℃ and 1000-2000 rpm for 4-12 h; and / or The S2 solution is soaked and swollen at 20-40°C for 12-14 hours; and / or The hydrolysis in S2 is carried out at 70-90℃ for 12-24 h; and / or The soaking and swelling in S4 is carried out at room temperature for 2-4 hours; and / or The HAuCl4 solution was continuously stirred at 50-60°C for 5-7 h; and / or The stirring time at the boiling temperature is 12-24 h.

7. The preparation method according to claim 6, characterized in that, The HAuCl4 solution has a mass percentage concentration of 0.4~0.6% (w / v); and / or The initial mass percentage concentration of the sodium citrate solution is 20-25% (w / v), and it is added at 1-3‰ (v / v) of the volume of the HAuCl4 solution.

8. The resin-based nanocomposite material prepared by any of the preparation methods described in claims 2-7.

9. The application of the resin-based nanocomposite material of claim 1 or the resin-based nanocomposite material of claim 8 in the detection of volatile substances and / or substances with inherently weak Raman signals.

Images