Photoresponse type polymer ultrathin nanosheet as well as preparation method and application thereof
Photoresponsive polymer ultrathin nanomaterials were synthesized by Suzuki coupling reaction and solvent evaporation self-assembly method, solving the problem of synthesizing amphiphilic alternating copolymers and realizing the preparation of efficient and stable photoresponsive materials, thus expanding their application in fields such as smart sensing and catalyst supports.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-27
- Publication Date
- 2026-03-10
AI Technical Summary
Existing technologies make it difficult to efficiently synthesize amphiphilic alternating copolymers, resulting in cumbersome, poorly repeatable, and unstable preparation processes for photoresponsive materials, which cannot meet the application requirements in fields such as intelligent sensing and controlled release.
An amphiphilic alternating copolymer containing azobenzene derivatives in the main chain was synthesized using the Suzuki coupling reaction. The photoresponsive polymer ultrathin nanomaterials were formed by solvent evaporation-induced self-assembly. The azobenzene structure endowed the material with unique photoresponsive properties, avoiding the design of complex and expensive materials.
A simple, reproducible, and highly stable photoresponsive polymer ultrathin nanosheet was prepared, exhibiting excellent photoresponsiveness and suitable for catalyst supports and applications in biomedicine and molecular detection.
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Figure CN121628059A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of organic ultrathin nanomaterials, and particularly relates to a light-responsive polymer ultrathin nanosheet and a preparation method and application thereof. BACKGROUND
[0002] Two-dimensional polymer ultrathin nanomaterials have the advantages of large specific surface area, ultrathin structure, good stability, and many exposed reaction sites, and have attracted widespread attention in many fields such as catalysis, separation, and sensing. Amphiphilic alternating copolymers (AACs) have a unique molecular structure due to strictly alternating structural units and a fixed hydrophilic-hydrophobic ratio, which endows AACs with excellent self-assembly characteristics. AACs self-assembly provides an ideal solution for the preparation of two-dimensional polymer ultrathin nanomaterials. However, the efficient and green synthesis of AACs is limited by the lack of functional monomer types and polymerization methods, which greatly limits their application in the preparation of ultrathin two-dimensional polymer nanosheets.
[0003] Light stimulation has the characteristics of clean and easy availability, strong remote control, and precise and rapid reaction control, and is considered a promising intelligent response source. Azobenzene and its derivatives are a rich and inexpensive photoisomerization molecule with strong absorption in the ultraviolet to infrared band. Through light or heat, it can undergo cis-trans isomerization transformation. Due to its rapid light response ability, it has attracted widespread attention. Organic polymer materials containing azobenzene groups have extremely important applications in the fields of active light regulation of biomolecules, optical information storage materials, and nanomaterials.
[0004] However, existing technologies often rely on complex and expensive functional material systems (such as shape memory materials) to introduce light response characteristics, or fail to integrate azobenzene groups into the polymer backbone in a stable and effective manner, resulting in a complicated preparation process or poor material performance. Furthermore, the preparation process of existing methods may not be easy to control, have poor repeatability, or have low stability, affecting the practical application of the material. In the face of current demand for intelligent devices, it is of great significance to develop a two-dimensional polymer ultrathin nanosheet with stimulus responsiveness for applications in advanced fields such as intelligent sensing and controlled release. SUMMARY
[0005] One of the purposes of the present application is to provide a preparation method of a light response type polymer ultrathin nanosheet, which can synthesize an amphiphilic alternating copolymer by using Suzuki coupling reaction, and then obtain a two-dimensional light response type polymer ultrathin nanomaterial by solvent evaporation induced self-assembly, and by simply introducing a light response group azobenzene structure into the polymer system, the ultrathin organic material can be endowed with unique light response characteristics without designing complex and expensive shape memory materials; the reaction synthesis route is simple, raw materials are easy to obtain, and the product yield is high; the preparation process has the characteristics of simple operation, good repeatability, high stability and the like.
[0006] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: A preparation method of a light response type polymer ultrathin nanosheet, comprising the following steps: (1) adding dicyclohexyl carbodiimide, N-hydroxysuccinimide, N,N-diisopropylethylamine and 4-carboxyphenyl boronic acid pinacol ester into a solvent, reacting at room temperature, filtering, and obtaining an intermediate product; (2) adding the intermediate product in step (1) and triethylene glycol, a catalyst into a solvent, heating and reacting, purifying, and obtaining a phenyl boronic acid pinacol ester derivative; (3) adding 4,4-dibromoazobenzene, the phenyl boronic acid pinacol ester derivative, a palladium catalyst and potassium carbonate into a solvent and reacting, and obtaining an amphiphilic alternating copolymer; (4) dispersing the amphiphilic alternating copolymer in a solvent and self-assembling, and obtaining the same.
[0007] In the present application, the carboxyl group in 4-carboxyphenyl boronic acid pinacol ester is activated by using dicyclohexyl carbodiimide, N-hydroxysuccinimide and N,N-diisopropylethylamine to obtain an intermediate product; the intermediate product is reacted with triethylene glycol under the action of a catalyst to obtain a phenyl boronic acid pinacol ester derivative; 4,4-dibromoazobenzene is subjected to Suzuki coupling reaction with the phenyl boronic acid pinacol ester derivative under the action of a palladium catalyst and potassium carbonate to obtain an amphiphilic alternating copolymer containing azobenzene groups in the main chain. Subsequently, the dialyzed amphiphilic alternating azobenzene copolymer is dispersed in an equal volume of pure water / tetrahydrofuran solution, and placed in a constant temperature condition of 4 DEG C; the slow evaporation of tetrahydrofuran promotes the microphase separation of the amphiphilic copolymer, the solution becomes turbid, indicating that the polymer self-assembles, and finally forms a two-dimensional light response type polymer ultrathin nanosheet.
[0008] The amphiphilic alternating copolymer in the present application is an amphiphilic alternating copolymer containing a hydrophobic group of azobenzene derivative and a hydrophilic group of phenyl boronic acid pinacol ester derivative in the main chain, which can self-assemble to form an ultrathin two-dimensional nanosheet material by non-covalent interaction forces such as π-π interaction and hydrophobic interaction.
[0009] The amphiphilic alternating copolymer of the present invention is synthesized by Suzuki coupling reaction using 4,4-dibromoazobenzene and pinacol ester derivative of phenylboronic acid as monomers. When the amounts of the two monomers are close to 1:1, an alternating copolymerization reaction can be generated, and an amphiphilic alternating copolymer composed of strictly alternating hydrophilic and hydrophobic units is successfully formed. In this copolymer, the azo monomer acts as the hydrophobic unit, and the EG (ethylene glycol) chain in the pinacol ester derivative of phenylboronic acid acts as the hydrophilic unit.
[0010] Due to their unique topology and strict hydrophilic-hydrophobic ratio, the self-assembly behavior of alternating amphiphilic copolymers differs from that of other amphiphilic polymers. Compared to traditional polymer self-assembly, the strictly alternating AB sequence (A represents the hydrophobic azobenzene unit; B represents the hydrophilic pinacol ester derivative) in alternating polymer self-assembly results in a highly ordered molecular arrangement. Furthermore, the forced alternation of monomers through alternating polymerization reduces chain defects and facilitates self-assembly to form regular two-dimensional layered structures.
[0011] Furthermore, the molecular structural formula of the pinacol ester derivative of phenylboronic acid described in step (2) is as follows: ; In step (3), the molecular structural formula of the amphiphilic alternating copolymer is: n is an integer, and the value of n is between 10 and 100.
[0012] Further, in step (1), the molar ratio of 4-carboxyphenylboronic acid pinacol ester, dicyclohexylcarbodiimide, N-hydroxysuccinimide, and N,N-diisopropylethylamine is 1:(1~2):(1~2):(1~2); the ratio of the amount of 4-carboxyphenylboronic acid pinacol ester to the solvent is 1 mmol:(5~8) mL, and the solvent is N,N-dimethylformamide.
[0013] Furthermore, in step (1), the molar ratio of 4-carboxyphenylboronic acid pinacol ester, dicyclohexylcarbodiimide, N-hydroxysuccinimide, and N,N-diisopropylethylamine is 1:1:1:(1.0~1.1).
[0014] Further, in step (2), the molar ratio of the intermediate product, triethylene glycol, and catalyst is 1:(0.4~0.6):(0.7~2), and the molar ratio of the intermediate product to the solvent is (7~9) mmol:20 mL; the catalyst is 4-dimethylaminopyridine, and the solvent is N,N-dimethylformamide.
[0015] Furthermore, in step (2), the molar ratio of the intermediate product, triethylene glycol, and catalyst is 1:(0.5~0.55):(0.75~0.80).
[0016] Further, in step (1), the reaction time is 24~48 h; in step (2), the heating reaction temperature is 100~120 ℃ and the time is 48~72 h.
[0017] Further, in step (3), the molar ratio of 4,4-dibromoazobenzene, pinacol ester derivative of phenylboronic acid, potassium carbonate, and palladium catalyst is 1:(1~1.1):(1~3):(0.01~0.03), the volume ratio of 4,4-dibromoazobenzene to solvent is 0.08 mmol:(5~8) mL, the palladium catalyst is bis(triphenylphosphine)palladium dichloride, and the solvent is dioxane and water, with a volume ratio of dioxane to water of 5:1.
[0018] Furthermore, the molar ratio of 4,4-dibromoazobenzene to pinacol ester derivative of phenylboronic acid, potassium carbonate, and bis(triphenylphosphine)palladium dichloride is 1:(1~1.1):3:(0.02~0.025).
[0019] Furthermore, the preparation method of 4,4-dibromoazobenzene in step (3) is as follows: p-Bromoaniline was dissolved in dichloromethane to obtain a p-bromoaniline solution. Potassium persulfate was dissolved in water to obtain a potassium persulfate solution. The potassium persulfate solution was added to the p-bromoaniline solution, and the mixture was stirred and reacted. After separation and rotary evaporation, intermediate product A was obtained. Then, intermediate product A and p-bromoaniline were added to acetic acid to carry out an azo coupling reaction. After precipitation in water, filtration, and drying, 4,4-dibromoazobenzene was obtained.
[0020] In this invention, potassium persulfate is used to oxidize the amino group of p-bromoaniline to obtain intermediate product A; intermediate product A undergoes an azo coupling reaction with p-bromoaniline to obtain 4,4-dibromoazobenzene.
[0021] Furthermore, the molar ratio of p-bromoaniline to potassium persulfate is 1:(2~3), the molar ratio of p-bromoaniline to dichloromethane is 17.44 mmol:150~200 mL; the molar ratio of potassium persulfate to water is 34.88 mmol:150~200 mL; the molar ratio of intermediate A to p-bromoaniline is 1:(1~2), the molar ratio of p-bromoaniline to acetic acid is 18 mmol:80~100 mL; and the reaction time is 24~48 h.
[0022] Furthermore, the molar ratio of p-bromoaniline to potassium persulfate is 1:2; the molar ratio of intermediate product A to p-bromoaniline is 1:(1~1.1).
[0023] Furthermore, in step (3), the reaction is carried out in an inert gas atmosphere, the temperature of the reaction is 80~120℃, and the time is 48~72 h.
[0024] Further, in step (4), the concentration of the amphiphilic alternating copolymer in the solvent is 2~3 mg / mL, and the solvent is composed of pure water and tetrahydrofuran in a volume ratio of 1:1.
[0025] The second objective of this invention is to provide a photoresponsive polymer ultrathin nanosheet.
[0026] A photoresponsive polymer ultrathin nanosheet was prepared using the above-described preparation method.
[0027] The third objective of this invention is to provide an application of photoresponsive polymer ultrathin nanosheets in the preparation of catalyst supports.
[0028] Compared with the prior art, the beneficial effects of this invention are as follows: 1. This invention provides a method for preparing photoresponsive polymer ultrathin nanosheets. The method employs a Suzuki coupling reaction to synthesize an amphiphilic alternating polymer whose main chain contains hydrophobic groups of an azobenzene derivative and hydrophilic groups of a pinacol ester derivative of phenylboronic acid. Suzuki coupling offers advantages such as mild reaction conditions and high yield, ensuring the reliability and efficiency of the synthesis process. Then, through solution self-assembly in a mixed solution of tetrahydrofuran and water, the hydrophobic groups of the azobenzene derivative and the hydrophilic groups of the pinacol ester derivative of phenylboronic acid are utilized to obtain photoresponsive two-dimensional polymer ultrathin nanosheet materials through non-covalent interactions such as π-π interactions and hydrophobic interactions. This invention, by simply introducing the photoresponsive azobenzene structure into the polymer main chain, can endow ultrathin organic materials with unique photoresponsive properties without the need for designing complex and expensive shape memory materials.
[0029] 2. This invention provides a method for preparing photoresponsive polymer ultrathin nanosheets, which is simple, easy to implement, highly reproducible, and highly stable.
[0030] 3. The two-dimensional photoresponsive polymer ultrathin nanomaterials prepared by this invention have two-dimensional ultrathin nanostructures and excellent photoresponsiveness. These photoresponsive polymer ultrathin nanosheets can not only be used as catalyst supports, but also have broad application prospects in biomedicine, molecular detection, catalysis and other fields through the preparation method in this technical solution. Attached Figure Description
[0031] Figure 1 It is the 4,4-dibromoazobenzene in Example 1 of this invention. 1 H NMR spectrum; Figure 2 It is the pinacol ester derivative of phenylboronic acid in Example 1 of this invention. 1 H NMR spectrum; Figure 3 It is the amphiphilic alternating copolymer in Example 1 of this invention. 1 H NMR spectrum; Figure 4 This is a gel permeation chromatography characterization result of the amphiphilic alternating copolymer in Example 1 of the present invention; Figure 5 This is a TEM image of the photoresponsive polymer ultrathin nanosheet assembly in Example 1 of this invention; Figure 6 This is the AFM image of the photoresponsive polymer ultrathin nanosheet assembly in Example 1 of this invention; Figure 7 This is the UV-Vis spectrum of the amphiphilic alternating copolymer in tetrahydrofuran solution in Example 1 of this invention; Figure 7 (a) shows the UV-Vis absorption spectrum over time under 365 nm UV irradiation. Figure 7 (b) shows the UV-Vis absorption spectrum over time under 450 nm visible light irradiation; Figure 8 This is the UV-Vis spectrum of the photoresponsive polymer ultrathin nanosheets assembled in aqueous solution in Example 1 of this invention; Figure 8 (a) shows the UV-Vis absorption spectrum over time under 365 nm UV irradiation. Figure 8 (b) shows the UV-Vis absorption spectrum over time under 450 nm visible light irradiation; Figure 9 These are TEM images of ruthenium dioxide and ruthenium dioxide supported on photoresponsive polymer ultrathin nanosheets in Example 1 of this invention; Figure 9 (a) is a TEM image of ruthenium dioxide. Figure 9 (b) is a TEM image of ruthenium dioxide loaded onto the surface of a photoresponsive polymer ultrathin nanosheet; Figure 10 This is the polarization curve of the water oxidation reaction in 0.5M H2SO4 electrolyte using ruthenium dioxide supported on photoresponsive polymer ultrathin nanosheets as an electrocatalyst in Example 1 of the present invention. Detailed Implementation
[0032] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the embodiments, comparative examples, experimental examples, and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. Unless otherwise specified, the raw materials and preparation methods used in this invention are conventional materials and techniques in the art.
[0033] The molecules synthesized in this invention 1 H-NMR spectra were measured on an AVANCE400 (400MHz) NMR spectrometer with deuterated DMSO as solvent at 25 °C.
[0034] Example 1 This embodiment proposes a method for preparing photoresponsive polymer ultrathin nanosheets, including the following steps: (1) Preparation of 4,4-dibromoazobenzene: p-bromoaniline (17.44 mmol) was dissolved in 150 mL of dichloromethane (DCM) to prepare a p-bromoaniline solution, and potassium persulfate (34.88 mmol) was dissolved in 150 mL of deionized water to prepare an aqueous solution of potassium persulfate; then the completely dissolved potassium persulfate aqueous solution was slowly added dropwise to the above p-bromoaniline solution and stirred overnight at room temperature; after the reaction was completed, the mixed solution was diluted with DCM and extracted, and the obtained organic phase was dried with anhydrous sodium sulfate (Na2SO4); after filtration, the organic solvent was removed by rotary evaporation to obtain a green oily liquid intermediate A; then, p-bromoaniline (18.02 mmol) and 80 mL of acetic acid were added to intermediate A (17.44 mmol) in sequence; the mixture was stirred overnight at room temperature; after the reaction was completed, the solution was precipitated with deionized water, then filtered and dried at 30 °C. 4,4-Dibromoazobenzene was dried in a vacuum oven at ℃ to constant weight, yielding an orange solid. Its NMR characterization is shown in [reference needed]. Figure 1 The specific reaction formula is: .
[0035] (2) Preparation of pinacol ester derivative of phenylboronic acid: In a 100 mL single-necked gai-shaped flask, 4-carboxyphenylboronic acid pinacol ester (4.03 mmol), dicyclohexylcarbodiimide (DCC) (4.03 mmol), N-hydroxysuccinimide (4.03 mmol), and 0.75 mL of N,N-diisopropylethylamine were added sequentially, and then dissolved in 20 mL of ultra-dry N,N-dimethylformamide. The reaction was carried out at room temperature for 24 h. After the reaction was completed, a clear and transparent liquid was obtained by filtration, which was the intermediate product. Subsequently, triethylene glycol (3.66 mmol), 4-dimethylaminopyridine (5.66 mmol), and 20 mL of N,N-diisopropylethylamine were added sequentially to the intermediate product (7.20 mmol). mL of ultra-dry N,N-dimethylformamide was reacted in a constant-temperature oil bath at 120℃ for 3 days. After the reaction was completed, the organic solvent was removed by rotary evaporation, and the crude product was purified by column chromatography with n-hexane:ethyl acetate = 3:2 (v / v) as the developing solvent. The final product was a brown oily liquid pinacol ester derivative of phenylboronic acid, and its NMR characterization is shown in [reference needed]. Figure 2 The specific molecular formula is: .
[0036] (3) Preparation of amphiphilic alternating copolymer: 4,4-dibromoazobenzene (0.080 mmol) and pinacol ester derivative of phenylboronic acid (0.082 mmol) were placed in a Shrek flask filled with nitrogen. Potassium carbonate (0.24 mmol) and bis(triphenylphosphine)palladium dichloride (0.002 mmol) were added sequentially. Then, 1,4-dioxane was dissolved in 5 mL of ultra-dry 1,4-dioxane and 1 mL of deionized water. The mixture was reacted at 100 °C for 72 h. The precipitate was then dissolved and precipitated three times in diethyl ether, centrifuged, and dried to constant weight in a vacuum drying oven at 35 °C to obtain a light brown solid, which is the amphiphilic alternating copolymer with a molecular weight of 45300 g mol. -1 Its molecular structure is shown below, and its NMR characterization is shown in [reference needed]. Figure 3 The molecular weight of the prepared amphiphilic alternating copolymers was characterized by gel permeation chromatography, such as... Figure 4 As shown.
[0037] (4) Preparation of photoresponsive polymer ultrathin nanosheet assemblies: The dialyzed amphiphilic alternating copolymer was prepared into a solution using pure water / tetrahydrofuran (volume ratio of 1:1) as a solvent. The concentration of the amphiphilic alternating copolymer in the solvent was 2 mg / mL. Then, under constant temperature of 4 °C, the tetrahydrofuran was allowed to slowly evaporate to obtain two-dimensional polymer ultrathin nanosheet assemblies. The prepared nanosheets had a lateral dimension of 3-8 μm and a thickness of 1-1.5 nm. Its transmission electron microscope image is shown below. Figure 5 As shown, the atomic force microscope image is as follows. Figure 6As shown.
[0038] Depend on Figure 5 and Figure 6 As can be seen, the photoresponsive polymer ultrathin nanosheet assembly obtained by this invention exhibits a two-dimensional nanosheet structure.
[0039] Example 2 This embodiment proposes a method for preparing photoresponsive polymer ultrathin nanosheets, including the following steps: (1) Preparation of 4,4-dibromoazobenzene: p-bromoaniline (17.44 mmol) was dissolved in 150 mL of dichloromethane (DCM) to prepare a DCM solution, and potassium persulfate (43.6 mmol) was dissolved in 150 mL of deionized water to prepare an aqueous solution of potassium persulfate; then the completely dissolved potassium persulfate aqueous solution was slowly added dropwise to the above p-bromoaniline solution, and stirred overnight at room temperature; after the reaction was completed, the mixed solution was diluted with DCM and extracted, and the obtained organic phase was dried with anhydrous sodium sulfate (Na2SO4); after filtration, the organic solvent was removed by rotary evaporation to obtain a green oily liquid intermediate A; then, p-bromoaniline (17.85 mmol) and 80 mL of acetic acid were added to intermediate A (17.00 mmol) in sequence; and stirred overnight at room temperature; after the reaction was completed, the solution was precipitated with deionized water, then filtered and dried at 30 °C. The product was dried in a vacuum oven at ℃ to constant weight, finally yielding an orange solid, 4,4-dibromoazobenzene.
[0040] (2) Preparation of pinacol ester derivative of phenylboronic acid: In a 100 mL single-necked flask, 4-carboxyphenylboronic acid pinacol ester (4.03 mmol), dicyclohexylcarbodiimide (DCC) (6.05 mmol), N-hydroxysuccinimide (6.05 mmol), and 0.8 mL of N,N-diisopropylethylamine were added sequentially, and then dissolved in 20 mL of ultra-dry N,N-dimethylformamide. The mixture was reacted at room temperature for 36 h. After the reaction was completed, a clear and transparent liquid was obtained by filtration, which was the intermediate product. Subsequently, triethylene glycol (4.55 mmol), 4-dimethylaminopyridine (6.55 mmol), and 20 mL of ultra-dry N,N-dimethylformamide were added sequentially to the intermediate product (9.00 mmol). The mixture was then dissolved in 100 mL of ultra-dry N,N-dimethylformamide. The reaction was carried out in a constant temperature oil bath for 3 days. After the reaction was completed, the organic solvent was removed by rotary evaporation, and the crude product was purified by column chromatography with hexane:ethyl acetate = 3:2 (v / v) as the developing solvent. Finally, a brown oily liquid pinacol ester derivative of phenylboronic acid was obtained.
[0041] (3) Preparation of amphiphilic alternating copolymer: 4,4-dibromoazobenzene (0.080 mmol) and pinacol ester derivative of phenylboronic acid (0.085 mmol) were placed in a Shrek bottle filled with nitrogen, and then potassium carbonate (0.16 mmol) and bis(triphenylphosphine)palladium dichloride (0.0024 mmol) were added in sequence. Then, 5 mL of ultra-dry 1,4-dioxane and 1 mL of deionized water were used to dissolve it. The reaction was carried out at 120 °C for 48 h. The precipitate was then dissolved in diethyl ether three times, centrifuged, and dried in a vacuum drying oven at 35 °C to constant weight to obtain a light brown solid, which is the amphiphilic alternating copolymer.
[0042] (4) Preparation of photoresponsive polymer ultrathin nanosheet assembly: The amphiphilic alternating copolymer after dialysis was prepared into a solution using pure water / tetrahydrofuran (volume ratio of the two is 1:1) as solvent. The concentration of the amphiphilic alternating copolymer in the solvent was 3 mg / mL. Then, under constant temperature of 4 °C, the tetrahydrofuran was allowed to slowly evaporate to obtain a two-dimensional polymer ultrathin nanosheet assembly.
[0043] Example 3 This embodiment proposes a method for preparing photoresponsive polymer ultrathin nanosheets, including the following steps: (1) Preparation of 4,4-dibromoazobenzene: p-bromoaniline (17.44 mmol) was dissolved in 150 mL of dichloromethane (DCM) to prepare a DCM solution, and potassium persulfate (52.32 mmol) was dissolved in 150 mL of deionized water to prepare an aqueous solution of potassium persulfate; then the completely dissolved potassium persulfate aqueous solution was slowly added dropwise to the above p-bromoaniline solution and stirred overnight at room temperature; after the reaction was completed, the mixed solution was diluted with DCM and extracted, and the obtained organic phase was dried with anhydrous sodium sulfate (Na2SO4); after filtration, the organic solvent was removed by rotary evaporation to obtain a green oily liquid intermediate A; then, p-bromoaniline (18.15 mmol) and 80 mL of acetic acid were added to intermediate A (16.50 mmol) in sequence; the mixture was stirred overnight at room temperature; after the reaction was completed, the solution was precipitated with deionized water, then filtered and dried at 30 °C. The product was dried in a vacuum oven at ℃ to constant weight, finally yielding an orange solid, 4,4-dibromoazobenzene.
[0044] (2) Preparation of pinacol ester derivative of phenylboronic acid: In a 100 mL single-necked gai-shaped flask, 4-carboxyphenylboronic acid pinacol ester (4.03 mmol), dicyclohexylcarbodiimide (DCC) (8.06 mmol), N-hydroxysuccinimide (8.06 mmol), and 0.75 mL of N,N-diisopropylethylamine were added sequentially, and then dissolved in 20 mL of ultra-dry N,N-dimethylformamide. The reaction was carried out at room temperature for 48 h. After the reaction was completed, a clear and transparent liquid was obtained by filtration, which was the intermediate product. Subsequently, triethylene glycol (5.00 mmol), 4-dimethylaminopyridine (7.00 mmol), and 20 mL of N,N-diisopropylethylamine were added sequentially to the intermediate product (10.00 mmol). mL of ultra-dry N,N-dimethylformamide was reacted in a constant temperature oil bath at 120℃ for 3 days. After the reaction was completed, the organic solvent was removed by rotary evaporation, and the crude product was purified by column chromatography with hexane:ethyl acetate = 3:2 (v / v) as the developing solvent. Finally, a brown oily liquid pinacol ester derivative of phenylboronic acid was obtained.
[0045] (3) Preparation of amphiphilic alternating copolymer: 4,4-dibromoazobenzene (0.080 mmol) and pinacol ester derivative of phenylboronic acid (0.088 mmol) were placed in a Shrek bottle filled with nitrogen, and then potassium carbonate (0.24 mmol) and bis(triphenylphosphine)palladium dichloride (0.0016 mmol) were added in sequence. Then, 5 mL of ultra-dry 1,4-dioxane and 1 mL of deionized water were used to dissolve it. The reaction was carried out at 120 °C for 72 h. The precipitate was then dissolved in diethyl ether three times, centrifuged, and dried in a vacuum drying oven at 35 °C to constant weight to obtain a light brown solid, which is the amphiphilic alternating copolymer.
[0046] (4) Preparation of photoresponsive polymer ultrathin nanosheet assembly: The amphiphilic alternating copolymer after dialysis was prepared into a solution using pure water / tetrahydrofuran (volume ratio of the two is 1:1) as solvent. The concentration of the amphiphilic alternating copolymer in the solvent was 2 mg / mL. Then, under constant temperature of 4 °C, the tetrahydrofuran was allowed to slowly evaporate to obtain a two-dimensional polymer ultrathin nanosheet assembly.
[0047] Experimental Example 1 The amphiphilic alternating copolymer obtained in Example 1 of this invention was dissolved in tetrahydrofuran solution; the two-dimensional polymer ultrathin nanosheet assembly obtained in Example 1 was dissolved in aqueous solution, and ultraviolet-visible spectral scanning analysis was performed on both. The ultraviolet light source in the ultraviolet-visible spectroscopy was a Uvata UP114 lamp with a wavelength of 365 nm and an intensity of 10 mW / cm². 2 The visible light source is an Uvata UP114 lamp with a wavelength of 450 nm and an intensity of 10 mW / cm². 2 The results are as follows: Figure 7 andFigure 8 As shown.
[0048] from Figure 7 and Figure 8 As can be seen, the UV-Vis spectroscopy indicates that the intensity of the characteristic absorption peak corresponding to trans-azo in the amphiphilic alternating copolymer and the two-dimensional polymer ultrathin nanosheet assembly gradually decreases with the extension of UV irradiation time, while the absorbance of the characteristic peak corresponding to cis-azo increases accordingly. Subsequent irradiation with visible light results in the opposite change, with a rapid transition within 50 seconds, demonstrating excellent photoresponse characteristics.
[0049] Experimental Example 2 The photoresponsive polymer ultrathin nanosheet assembly obtained in Example 1 of this invention was used as a ruthenium dioxide catalyst support: 100 μL of ruthenium dioxide at a concentration of 1 mg / mL was added to the obtained two-dimensional polymer ultrathin nanosheet assembly, thereby loading ruthenium dioxide onto the surface of the two-dimensional polymer ultrathin nanosheets. Its transmission electron microscope image is shown below. Figure 9 As shown, the polarization curve of the ruthenium dioxide catalyst containing the photoresponsive polymer ultrathin nanosheet assembly of the present invention in the water oxidation reaction in 0.5M H2SO4 electrolyte is as follows. Figure 10 As shown. A ruthenium dioxide catalyst is used as a comparison.
[0050] from Figure 9 As can be seen, the left figure (a) is a TEM image of ruthenium dioxide, which shows severe agglomeration. The right figure (b) is a TEM image of ruthenium dioxide loaded onto the surface of the prepared photoresponsive polymer ultrathin nanosheets, where ruthenium dioxide can be dispersed on the nanosheet surface without agglomeration.
[0051] from Figure 10 It can be seen that loading ruthenium dioxide onto the surface of two-dimensional polymer ultrathin nanosheets as an electrocatalyst significantly improves the water oxidation performance in 0.5 M H2SO4 electrolyte compared to using ruthenium dioxide alone.
[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.
Claims
1. A method for preparing a photoresponsive ultrathin polymer nanosheet, characterized in that, It comprises the following steps: (1) adding dicyclohexyl carbodiimide, N-hydroxysuccinimide, N,N-diisopropyl ethylamine and 4-carboxyphenyl boronic acid pinacol ester into a solvent, reacting at room temperature, filtering to obtain an intermediate product; (2) adding the intermediate product in step (1) and triethylene glycol, a catalyst into a solvent, heating to react, purifying to obtain a phenyl boronic acid pinacol ester derivative; (3) adding 4,4-dibromoazobenzene, the phenyl boronic acid pinacol ester derivative, a palladium catalyst and potassium carbonate into a solvent to react, obtaining an amphiphilic alternating copolymer; (4) dispersing the amphiphilic alternating copolymer in a solvent to self-assemble, thus obtaining the product.
2. The method for preparing photoresponsive polymer ultrathin nanosheets according to claim 1, characterized in that, The molecular structural formula of the phenyl boronic acid pinacol ester derivative in step (2) is ； In step (3), the molecular structural formula of the amphiphilic alternating copolymer is n is an integer, n is 10-100.
3. The method for preparing photoresponsive polymer ultrathin nanosheets according to claim 1, characterized in that, In step (1), the molar ratio of 4-carboxyphenyl boronic acid pinacol ester, dicyclohexyl carbodiimide, N-hydroxysuccinimide and N,N-diisopropyl ethylamine is 1:(1-2):(1-2):(1-2); the use amount ratio of 4-carboxyphenyl boronic acid pinacol ester and the solvent is 1 mmol:(5-8) mL, and the solvent is N,N-dimethylformamide. 4.The method of claim 1, wherein the method is characterized by, In step (2), the molar ratio of the intermediate product, triethylene glycol and the catalyst is 1:(0.4-0.6):(0.7-2), the use amount ratio of the intermediate product and the solvent is (7-9) mmol:20 mL; the catalyst is 4-dimethylaminopyridine, and the solvent is N,N-dimethylformamide. 5.The method of claim 1, wherein the method is characterized by, In step (1), the reaction time is 24-48 h; in step (2), the heating reaction temperature is 100-120 ℃, and the time is 48-72 h. 6.The method of claim 1, wherein the light-responsive polymer ultrathin nanosheets are prepared by the method of claim 1. In step (3), the molar ratio of 4,4-dibromoazobenzene, the phenyl boronic acid pinacol ester derivative, potassium carbonate and the palladium catalyst is 1:(1-1.1):(1-3):(0.01-0.03), the use amount ratio of 4,4-dibromoazobenzene and the solvent is 0.08 mmol:(5-8) mL; the palladium catalyst is bis(triphenylphosphine)palladium dichloride; and the solvent is dioxane and water, and the volume ratio of dioxane and water is 5:
1.
7. The method for preparing photoresponsive polymer ultrathin nanosheets according to claim 1, characterized in that, In step (3), the reaction is carried out in an inert gas atmosphere, the reaction temperature is 80-120 ℃, and the time is 48-72 h. 8.The method of claim 1, wherein the method is characterized by, In step (4), the concentration of the amphiphilic alternating copolymer in the solvent is 2-3 mg / mL, and the solvent is composed of pure water and tetrahydrofuran at a volume ratio of 1:
1.
9. A photo-responsive polymer ultrathin nanosheet, characterized in that, The preparation method is prepared by any one of claims 1-8.
10. Application of the light-responsive polymer ultrathin nanosheet in claim 9 in the preparation of a catalyst carrier.