Preparation Method of Recyclable Orthogonal Dynamic Covalent Fluorescent Polymer Materials

Abstract

The invention discloses a preparation method of a recyclable orthogonal dynamic covalent fluorescent polymer material: connecting a phenylboronic acid group to lipoic acid or a lipoic acid derivative through an esterification reaction or an amidation reaction of its active ester to obtain benzyl lipoate borate and its derivatives or N-benzylboronic acid lipoamide and its derivatives. After heating and melting the above purified small molecules and removing water, transfer them to a substrate while it is still hot and spread them to obtain a yellow transparent supramolecular polymer. Irradiate it with an ultraviolet-visible light source to obtain the recyclable orthogonal dynamic covalent fluorescent polymer material containing disulfide bonds and borate ester bonds. The dynamic polymer material prepared by the invention is mainly crosslinked and self-assembled by dynamic disulfide bonds, dynamic borate ester bonds, and hydrogen bonds; it has strong fluorescence emission that can vary with temperature under light excitation at a wavelength of 400 nm; it has good biocompatibility, high stability, good homogeneity, and excellent mechanical properties. The preparation method of the invention is simple, and the process is safe and reliable.

Description

Technical Field

[0001] The present invention belongs to the technical field of material chemistry, and specifically relates to a preparation method of a recyclable orthogonal dynamic covalent fluorescent polymer material. Background Art

[0002] Since their commercialization in the early 20th century, polymer materials have increasingly become irreplaceable synthetic materials in human production and life, greatly promoting the development of the industrial revolution. High-performance polymers have attracted great interest due to their huge application potential in emerging materials such as flexible electronic devices, soft robots, and responsive materials. At the same time, in order to make synthetic polymer materials sustainable, degradable, and recyclable, developing recyclable dynamic polymer materials to build a future plastic circular economy has become an urgent task for chemists. Recent research work has shown that the bio-derived small molecule lipoic acid has ring-opening polymerization properties under stimuli such as light and heat, and the intrinsic dynamics of its disulfide bond make it perform excellently in recyclability; small molecules of lipoic acid can be efficiently modified through simple reactions to synthesize small molecules containing more than two types of dynamic covalent bonds, and further construct a polymer network with multiple dynamic bonds. A typical example is that Wang et al. introduced phenylboronic acid groups into a polydimethylsiloxane (PDMS) polymer network through an aldehyde-amine condensation reaction, and after dehydration, a dynamic polymer network containing siloxane bonds, borate ester bonds, and imine bonds was formed, thus obtaining a room-temperature self-healing material that can be stretched 42 times and has force-induced color change characteristics (Highly stretchable and stretch-induced fluorescencechromism self-healing materials based on boroxine and dynamic imine bond, J. Mater. Chem. C, 2022, 10, 10895). Such polymers generally have multiple properties and broad application prospects, but still face certain challenges in synthesis and preparation, and their mechanical strength is not satisfactory. How to orthogonally synthesize a multiple dynamic bond network and make their respective properties unaffected, so as to exhibit more comprehensive and efficient properties at the macroscopic scale, has become a challenge in this field. Summary of the Invention

[0003] The purpose of the present invention is to provide a preparation method of a recyclable orthogonal dynamic covalent fluorescent polymer material. To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0004] The present invention provides a preparation method of a recyclable orthogonal dynamic covalent fluorescent polymer material, comprising the following steps:

[0005] 1), Prepare benzyl thioctic acid borate or its derivative: Dissolve thioctic acid or its derivative, hydroxymethylphenylboronic acid or its derivative, and the catalyst 4-dimethylaminopyridine in an organic solvent. After dissolution, add molecular sieve and stir at room temperature for 10 min; Dissolve 1-ethyl-3(3-dimethylpropylamine)carbodiimide in a small amount of dichloromethane and add it dropwise to the system. Stir at room temperature for more than 12 h under light-shielded conditions; After the reaction is completed, filter off the molecular sieve, and then wash it successively with dilute hydrochloric acid solution, saturated sodium chloride solution, and saturated sodium bicarbonate solution. Finally, remove water with anhydrous sodium sulfate and filter. The obtained filtrate is concentrated and then separated by column chromatography to obtain the product, which is the recyclable orthogonal dynamic covalent fluorescent polymer monomer small molecule I containing a disulfide bond and a borate bond, that is, benzyl thioctic acid borate or its derivative;

[0006] The molar ratio of the thioctic acid or its derivative, hydroxymethylphenylboronic acid or its derivative, 4-dimethylaminopyridine, and 1-ethyl-3(3-dimethylpropylamine)carbodiimide is 1.2:1:1.2:(1.2 - 1.5);

[0007] The organic solvent is dichloromethane, acetonitrile, or acetone;

[0008] Or: Prepare N-benzylboronoylthioctamide or its derivative: Dissolve thioctic acid or its derivative and N,N'-disuccinimidyl carbonate in an organic solvent and stir. After dissolution, slowly add triethylamine and react at room temperature for more than 12 h. After the reaction is completed, concentrate the reaction solution and drop it into 5% NaHCO 3 solution to precipitate a yellow solid. Filter by suction and wash with water to obtain the intermediate thioctic acid N-hydroxysuccinimide ester or its derivative; Dissolve the intermediate or its derivative and aminomethylphenylboronic acid hydrochloride or its derivative in an organic mixed solvent and protect it with nitrogen; Add triethylamine to the system with a syringe to start the reaction, and a white solid precipitates to obtain the recyclable orthogonal dynamic covalent fluorescent polymer monomer small molecule II containing a disulfide bond and a borate bond, that is, N-benzylboronoylthioctamide or its derivative;

[0009] The organic mixed solvent is at least one of acetonitrile, acetone, tetrahydrofuran, ethanol, and water;

[0010] The molar ratio of the thioctic acid or its derivative, N,N'-disuccinimidyl carbonate, triethylamine, and aminomethylphenylboronic acid hydrochloride or its derivative is 1:(1.2 - 1.5):3:1;

[0011] 2) Preparation of recyclable orthogonal dynamic covalent fluorescent polymer materials: Under solvent-free conditions, place benzyl thioctic acid borate or its derivatives, or N-benzylthiocapramide borate or its derivatives in a reaction vessel equipped with a stirring device. Heat it to 100-200 °C to melt under nitrogen protection, stir for 2-10 min, stop heating after the bubbles in the liquid disappear and it becomes homogeneous, pour it onto a mold while it is still hot, or pour it onto a polytetrafluoroethylene film and use a heavy object with a flat surface to press and shape it to obtain a hot polymer. Irradiate it with a UV-visible light source with a power of more than 50 W and a wavelength of 300-450 nm for 20-60 min until the polymer completely exhibits blue-green fluorescence, and obtain the recyclable orthogonal dynamic covalent fluorescent polymer materials.

[0012] The monomeric small molecule I, that is, the structure of benzyl thioctic acid borate or its derivatives is shown in Formula I:

[0013]

[0014] In Formula I, R 1 is hydrogen or C 1 ~C 4 linear or branched alkyl, R 2 is hydrogen or carboxyl, R 3 is hydrogen or C 1 ~C 4 linear or branched alkyl, R 4 , R 5 , R 6 are hydrogen, halogen atoms or R7 and R8 are hydrogen or C 1 ~C 2 linear or branched alkyl, and n is an integer from 1 to 5, and m is an integer from 1 to 3.

[0015] The monomeric small molecule II, that is, the structure of N-benzylthiocapramide borate or its derivatives is shown in Formula II:

[0016]

[0017] In Formula II, R 1 is hydrogen or C 1 ~C 4 linear or branched alkyl, R 2 is hydrogen or carboxyl, R 3 is hydrogen or C 1 ~C 4 linear or branched alkyl, R 4 , R 5 , R 6 are hydrogen, halogen atoms or R7 and R8 are hydrogen or C 1 ~C 2A linear or branched alkyl group, n is an integer from 1 to 5, and m is an integer from 1 to 3.

[0018] The structure of the lipoic acid and its derivatives is shown in Formula III

[0019]

[0020] In Formula III, R1 is hydrogen or a C1-C4 linear or branched alkyl group, R2 is hydrogen or a carboxyl group, and n is an integer from 1 to 5.

[0021] The lipoic acid or lipoic acid derivative is preferably lipoic acid or lipoic acid diacid. In the structural formula III of the lipoic acid, R 1 is hydrogen, R 2 is hydrogen, and n is 3; in the structural formula III of the lipoic acid diacid, R 1 is hydrogen, R 2 is a carboxyl group, and n is 2.

[0022] The mold is a metal mold with a polytetrafluoroethylene coating and a thickness not exceeding 0.5 mm.

[0023] Due to the adoption of the above technical solutions, the present invention has the following advantages and beneficial effects:

[0024] The raw materials used in the present invention are beneficial to the human body, biocompatible, widely sourced, inexpensive and easily available, and have industrial feasibility; the reaction conditions are mild, the process is safe, the reaction yield is high, the post-treatment is simple, and no waste water or waste residue harmful to the environment is generated, meeting the requirements of green chemistry.

[0025] In the lipoic acid boronic acid benzyl ester polymer network in the polymer material prepared by the present invention, multiple chemical bonds such as disulfide bonds, borate ester bonds, and hydrogen bonds are connected. Without adding additional covalent cross-linking agents, the five-membered ring of the lipoic acid and its derivatives has reversible dynamic covalent polymerization / depolymerization characteristics, making the mechanical properties of the polymer richer.

[0026] The material prepared by the present invention orthogonally concentrates disulfide bonds and borate ester bonds in the same polymer system, making the material responsive to temperature, light, and humidity, and the stimulation responses of different factors to the material do not interfere with each other. In particular, the fluorescence property of the polymer can be used as a judgment standard for whether the monomer polymerization is complete, and also expands the application prospects of the material in the optical field. Brief Description of the Drawings

[0027] Figure 1 Schematic diagram of the molecular structure and appearance of the polymer material prepared in Example 1 of the present invention

[0028] Figure 2 X-ray diffraction pattern of the polymer material prepared in Example 1 of the present invention

[0029] Figures 3A - 3DSchematic diagrams of the rheological properties curve and thermal properties curve of the polymer material prepared in Example 1 of the present invention. Among them, 3A is a schematic diagram of the frequency conversion curve, 3B is a schematic diagram of the temperature change curve, 3C is a schematic diagram of the thermogravimetric curve, and 3D is a schematic diagram of the differential scanning calorimetry curve.

[0030] Figure 4 Schematic diagram of the attenuated total reflection-Fourier transform infrared absorption spectrum of the polymer material prepared in Example 1 of the present invention

[0031] Figure 5 Schematic diagram of the temperature-dependent fluorescence emission spectrum of the polymer material prepared in Example 1 of the present invention Detailed implementation manners

[0032] To illustrate the present invention more clearly, the following further describes the present invention in conjunction with preferred embodiments. Those skilled in the art should understand that the content specifically described below is illustrative rather than restrictive, and should not be used to limit the protection scope of the present invention.

[0033] The manufacturer from which the lipoic acid used in the examples was purchased is Aladdin, and its full name is (±)-α-lipoic acid (racemic), with a CAS number of 1077-28-7, an MDL number of MFCD00005474, a specification of 500 g, a purity of 99%, and a grade of reagent grade (RG).

[0034] The manufacturer from which N,N'-disuccinimidyl carbonate used in the examples was purchased is Adamas (adamas-beta), with a CAS number of 74124-79-1, an MDL number of MFCD00009767, a specification of 500 g, a purity of 99%, and a grade of reagent grade (RG).

[0035] The manufacturer from which 4-hydroxymethylphenylboronic acid used in the examples was purchased is TCI, with a CAS number of 59016-93-2, an MDL number of MFCD00792672, a specification of 100 g, a purity of 99%, and a grade of reagent grade (RG).

[0036] The manufacturer from which triethylamine used in the examples was purchased is Adamas (adamas-beta), with a CAS number of 121-44-8, an MDL number of MFCD00009051, a specification of 500 g, a purity of 99%, and a grade of reagent grade (RG).

[0037] The manufacturer from which 4-aminomethylphenylboronic acid hydrochloride used in the examples was purchased is TCI, with a CAS number of 75705-21-4, an MDL number of MFCD01632199, a specification of 100 g, a purity of 99%, and a grade of reagent grade (RG).

[0038] The 4-dimethylaminopyridine used in the examples was purchased from Adamas (adamas-beta), with a CAS number of 1122-58-3, an MDL number of MFCD00006418, a Merk number of, a specification of 500 g, a purity of 99%, and a grade of reagent grade (RG).

[0039] The 1-ethyl-3-(3-dimethylpropylamine)carbodiimide used in the examples was purchased from Adamas (adamas-beta), with a CAS number of 25952-53-8, an MDL number of MFCD00012503, a Merk number of, a specification of 500 g, a purity of 99%, and a grade of reagent grade (RG).

[0040] Example 1

[0041] Dissolve 3 g of lipoic acid and 1.7764 g of 4-dimethylaminopyridine in 30 ml of anhydrous DCM, and dissolve 1.8413 g of 4-hydroxymethylphenylboronic acid in 30 ml of acetonitrile. After dissolution, add molecular sieve, and stir at room temperature for 10 min. Dissolve 2.7874 g of 1-ethyl-3-(3-dimethylpropylamine)carbodiimide in a small amount of DCM, and add it dropwise to the system within 10 min. Stir at room temperature for 12 h under light-shielded conditions. After the reaction is completed, filter off the molecular sieve. Then wash it 3 times with dilute hydrochloric acid solution, saturated sodium chloride solution, and saturated sodium bicarbonate solution respectively, and finally wash it with anhydrous sodium sulfate to remove water. After rotary evaporation and concentration, use dry column chromatography to obtain benzyl lipoate borate.

[0042] Under solvent-free conditions, place the dried benzyl lipoate borate in a reaction vessel equipped with a stirring device, heat it to 160 °C to melt under nitrogen protection, stir for 5 min, stop heating after the bubbles in the liquid disappear and it becomes homogeneous, pour it onto a metal mold while it is still hot to obtain a polymer strip with a thickness of 0.5 mm, and irradiate it with a UV-visible light source with a power of 50 W and a wavelength of 365 nm for 3 h until the polymer completely exhibits fluorescence to obtain the polymer material.

[0043] The dynamic polymer molecular structure and appearance provided by the present invention are as Figure 1 shown. Figure 1 It is the molecular structure and appearance diagram of the dynamic polymer prepared in Example 1 of the present invention. Through the esterification reaction of lipoic acid and hydroxymethylphenylboronic acid, a yellow solid small molecule that is easy to carry out the next polymerization can be prepared. In an environment with low oxygen content, this small molecule can obtain a relatively stable polymer through simple heating and melting followed by light irradiation, without the need to additionally add cross-linking agents, etc. The polymer prepared by the present invention has good strength and is not easy to dissolve or melt.

[0044] The X-ray diffraction pattern of the dynamic polymer provided by the present invention is as Figure 2 shown,Figure 2 X-ray diffraction pattern of the dynamic polymer prepared in Example 1 of the present invention. It can be seen from the figure that there are no sharp diffraction peaks, and there are no characteristic peaks in the small-angle diffraction spectrum, indicating that the polymer material is amorphous and there is no microphase separation.

[0045] The rheological property curve and thermal property curve of the dynamic polymer provided by the present invention are shown in Figure 3. Figure 3 is the rheological property curve and thermal property curve of the dynamic polymer prepared in Example 1 of the present invention. Among them, 3A is a schematic diagram of the frequency conversion curve. It can be seen from the figure that the change of modulus with frequency proves the dynamics of the dynamic network, and at the same time, the material shows the characteristics similar to those of rubber materials. 3B is a schematic diagram of the temperature change curve. It can be seen from the figure that the modulus decreases continuously with the increase of temperature, proving the temperature responsiveness of the polymer. The dynamic bonds are broken at high temperature, resulting in the depolymerization of the polymer. 3C is a schematic diagram of the thermogravimetric curve. The decomposition temperatures of both the monomer thioctic acid benzyl borate molecule and the dynamic polymer are about 240 °C, but the water absorption of the monomer molecule is stronger than that of the polymer, proving that the photo-crosslinked dynamic polymerization process improves the network crosslinking degree and makes the structure dense. 3D is a schematic diagram of the differential scanning calorimetry curve. It can be seen from the figure that the glass transition temperature of the dynamic polymer prepared by the present invention is 36 °C and there is no fixed melting point. The dynamic polymer prepared by the present invention has strong mechanical properties and thermodynamic properties.

[0046] The attenuated total reflection-Fourier transform infrared absorption spectrum of the dynamic polymer provided by the present invention is as Figure 4 shown. Figure 4 Schematic diagram of the attenuated total reflection-Fourier transform infrared absorption spectrum of the dynamic polymer prepared in Example 1 of the present invention. It can be seen from the figure that there is a broad peak at about 3300 cm -1 for the thioctic acid benzyl borate monomer, indicating the existence of intermolecular hydrogen bonds and hydroxyl groups in the monomer. The peaks at about 1715 cm -1 and 1350 cm -1 for the monomer and the polymer prove the existence of ester groups. The two sharp peaks at about 700 cm -1 for the polymer are the characteristic peaks of B-O-B, and the absence in the monomer indicates that boric acid has polymerized during the polymerization process, proving the existence of borate ester.

[0047] The schematic diagram of the temperature-variable fluorescence emission spectrum of the dynamic polymer provided by the present invention is as Figure 5 shown. Figure 5 Schematic diagram of the temperature-variable fluorescence emission spectrum of the dynamic polymer prepared in Example 1 of the present invention. It can be seen from the figure that the fluorescence emission wavelength range of the dynamic polymer is relatively wide, and the intensity peak is at about 500 nm. With the increase of temperature, the fluorescence intensity gradually weakens and there is a blue shift of the maximum wavelength. The dynamic polymer prepared by the present invention has fluorescence properties that change with temperature.

[0048] Example 2

[0049] Dissolve 3g lipoic acid and 4.4698g N,N'-disuccinimidyl carbonate in 200mL acetonitrile and stir. After dissolution, slowly add 6.25mL triethylamine. React at room temperature for more than 12h. After the reaction is completed, concentrate the reaction solution and add it dropwise to 250mL 5% NaHCO 3 In the solution, a yellow solid is precipitated, filtered, and washed to obtain 4.4114g of intermediate lipoic acid N-hydroxysuccinimide ester. The obtained intermediate is all dissolved in 100mL acetone, 2.7253g 4-aminomethylphenyl boric acid hydrochloride is dissolved in 100mL deionized water and mixed with the acetone solution of the intermediate, and nitrogen protection is passed through. 2mL triethylamine is added to the system with a syringe while stirring to start the reaction. The reaction precipitates a white solid, which is filtered and washed to obtain N-boric acid benzyl lipoamide.

[0050] Under solvent-free conditions, the dried N-boric acid benzyl lipoamide is placed in a reaction container with a stirring device, heated to 170° C. to melt under nitrogen protection, stirred for 5 minutes, and the heating is stopped after the bubbles in the liquid disappear and the liquid becomes uniform. The liquid is poured onto a metal mold while hot to obtain a 0.5 mm thick polymer strip, which is irradiated with an ultraviolet-visible light source with a power of 50 W and a wavelength of 365 nm for 3 hours until the polymer completely exhibits fluorescence, thereby obtaining the polymer material.

[0051] Embodiment 3 to Embodiment 10

[0052] Different fluorescent polymers were obtained by changing the type of lipoic acid benzyl borate derivative or N-boric acid benzyl lipoamide derivative, heating temperature, heating time, illumination wavelength, and illumination time. Others were the same as in Example 1, see Table 1 for details.

[0053] Table 1

[0054]

[0055]

[0056] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited by the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. Preparation method of a recyclable orthogonal dynamic covalent fluorescent polymer material, Characterized in that: It includes the following steps: 1) Preparation of lipoic acid benzyl borate or its derivative: Dissolve lipoic acid or its derivative, hydroxymethylphenylboronic acid or its derivative, and the catalyst 4-dimethylaminopyridine in an organic solvent. After dissolution, add molecular sieve and stir at room temperature for 10 min; dissolve 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide in a small amount of dichloromethane and add it dropwise to the system, and stir at room temperature for more than 12 h under light-shielded conditions; after the reaction is completed, filter to remove the molecular sieve, and then wash successively with dilute hydrochloric acid solution, saturated sodium chloride solution, and saturated sodium bicarbonate solution. Finally, remove water with anhydrous sodium sulfate and filter. The obtained filtrate is concentrated and then subjected to column chromatography for separation and post-treatment to obtain the product, which is a recyclable orthogonal dynamic covalent fluorescent polymer monomer small molecule I containing a disulfide bond and a borate ester bond, namely lipoic acid benzyl borate or its derivative; The molar ratio of the lipoic acid or lipoic acid derivative, hydroxymethylphenylboronic acid or its derivative, 4-dimethylaminopyridine, and 1-ethyl-3(3-dimethylpropylamine)carbodiimide is 1.2:1:1.2:(1.2 - 1.5); The organic solvent is dichloromethane, acetonitrile or acetone; Or: To prepare N-benzylthiocapramide borate or its derivative: dissolve lipoic acid or its derivative and N,N'-disuccinimidyl carbonate in an organic solvent and stir. After dissolution, slowly add triethylamine and react at room temperature for more than 12 h. After the reaction, concentrate the reaction solution and drop it into 5% NaHCO 3 solution to precipitate a yellow solid. Filter by suction and wash with water to obtain the intermediate lipoic acid N-hydroxysuccinimide ester or its derivative; dissolve the intermediate or its derivative and aminomethylphenylboronic acid hydrochloride or its derivative in an organic mixed solvent and protect with nitrogen; add triethylamine to the system with a syringe to start the reaction, and a white solid will precipitate during the reaction to obtain a recyclable orthogonal dynamic covalent fluorescent polymer monomer small molecule II containing a disulfide bond and a borate ester bond, namely N-benzylthiocapramide borate or its derivative; The organic mixed solvent is at least one of acetonitrile, acetone, tetrahydrofuran, ethanol, and water; The molar ratio of the lipoic acid or lipoic acid derivative, N,N'-disuccinimidyl carbonate, triethylamine, and aminomethylphenylboronic acid hydrochloride or its derivative is 1:(1.2 - 1.5):3:1; 2) Preparation of the recyclable orthogonal dynamic covalent fluorescent polymer material: Under solvent-free conditions, place benzyl lipoic acid borate or its derivative, or N-benzylthiocapramide or its derivative in a reaction vessel equipped with a stirring device, heat it to 100 - 200 °C to melt under nitrogen protection, stir for 2 - 10 min, stop heating after the bubbles in the liquid disappear and it becomes a homogeneous state, pour it onto a mold while it is still hot, or pour it onto a polytetrafluoroethylene film and use a heavy object with a flat surface to press and shape it to obtain a hot polymer, and irradiate it with a UV-visible light source with a power of more than 50 w and a wavelength of 300 - 450 nm for 20 - 60 min until the polymer completely shows blue-green fluorescence, thus obtaining the recyclable orthogonal dynamic covalent fluorescent polymer material.

2. The preparation method of the orthogonal dynamic covalent fluorescent polymer material as described in claim 1, Characterized in that, The monomer small molecule I, that is, the structure of benzyl lipoic acid borate or its derivative is shown in Formula I: R in formula Ⅰ 1 is hydrogen or C 1 ~C 4 linear or branched alkyl, R 2 is hydrogen or carboxyl, R 3 is hydrogen or C 1 ~C 4 linear or branched alkyl, R 4 、R 5 、R 6 are hydrogen, halogen atom or R7 and R8 are hydrogen or C 1 ~C 2 linear or branched alkyl, n is an integer from 1 to 5, and m is an integer from 1 to 3.

3. The preparation method of the orthogonal dynamic covalent fluorescent polymer material as described in claim 1, Characterized in that, The monomer small molecule II, that is, the structure of N-benzylthiocapramide or its derivative is shown in Formula II: R in formula II 1 is hydrogen or C 1 ~C 4 linear or branched alkyl, R 2 is hydrogen or carboxyl group, R 3 is hydrogen or C 1 ~C 4 linear or branched alkyl, R 4 , R 5 , R 6 are hydrogen, halogen atom or R7 and R8 are hydrogen or C 1 ~C 2 linear or branched alkyl, n is an integer from 1 to 5, and m is an integer from 1 to 3.

4. The preparation method of the orthogonal dynamic covalent fluorescent polymer material as described in claim 1, characterized in That, the structure of the lipoic acid and its derivative is shown in Formula III In Formula III, R1 is hydrogen or a C1 - C4 straight-chain or branched-chain alkyl group, R2 is hydrogen or a carboxyl group, and n is an integer from 1 to 5.

5. The preparation method of the orthogonal dynamic covalent fluorescent polymer material as described in claim 4, Characterized in that, The lipoic acid or lipoic acid derivative is lipoic acid or lipoic diacid. In the structural formula Ⅲ of the lipoic acid, R 1 is hydrogen, R 2 is hydrogen, and n is 3; in the structural formula Ⅲ of the lipoic diacid, R 1 is hydrogen, R 2 is carboxyl, and n is 2.

6. The preparation method of the orthogonal dynamic covalent fluorescent polymer material as described in claim 1, Characterized in that, The mold is a metal mold with a polytetrafluoroethylene coating and a thickness not exceeding 0.5 mm.

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