Preparation method of end group functionalized polyoxazoline

Abstract

The invention discloses a preparation method of end-group-functionalized polyoxazoline, which comprises the following steps: mixing a weak Bronsted acid initiator, an ion exchange catalyst and an oxazoline monomer, and carrying out cationic ring-opening polymerization reaction to obtain the end-group-functionalized polyoxazoline. The preparation method of the end group functionalized polyoxazoline has the advantages of simple and convenient operation process, low equipment requirement, high atom economy, wide compatibility range of functional groups, high functionalization efficiency, low cost and the like, and the adopted initiator weak Bronsted acid is high in commercialization degree, diversified in structure and wide in source; and finally, the polyoxazoline with the functionalized end group, which is controllable in molecular weight, narrow in molecular weight distribution, adjustable in topological structure and adjustable in performance, can be prepared.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, and specifically to a method for preparing end-functionalized polyoxazoline. Background Technology

[0002] Polyoxazoline is a class of polyamide polymers containing peptide-like structures (e.g., poly(2-methyl-2-oxazoline) and poly(2-ethyl-2-oxazoline)). It has excellent chemical stability, good hydrophilicity and outstanding biocompatibility, and has a very broad application prospect in the biomedical field.

[0003] End-group functionalization is a cutting-edge technology in the field of polymers, which can optimize material performance and innovate functions by precisely controlling the chemical structure at the ends of molecular chains. In recent years, researchers have introduced diverse functional groups into the end groups of polyoxazolines, achieving not only directional coupling of polyoxazolines with other functional materials, but also constructing novel functional material systems with tunable performance at the molecular level, thus expanding the application boundaries of materials (for example, introducing double or triple bonds into the end groups of polyoxazolines can significantly enhance their ability to participate in click chemistry reactions). Currently, the end-group functionalization of polyoxazolines mainly adopts the following two methods: 1) using functionalized strong Brønsted acids or highly electrophilic initiators to achieve end-group functionalization of polyoxazolines. This method suffers from problems such as insufficient commercialization of functionalized products, limited functional group compatibility, complex synthesis processes, severe equipment corrosion, and poor end-group stability; 2) adding nucleophiles to cap the ends of polyoxazolines after the polymerization reaction to achieve end-group functionalization of polyoxazolines. This two-step method suffers from low stoichiometric efficiency (requiring the addition of excess terminator) and is also limited by the compatibility of specific functional groups. In summary, existing methods for end-group functionalization of polyoxazolines all have significant technical bottlenecks, which severely restrict the development and practical application of end-group functionalized polyoxazolines.

[0004] Therefore, it is of great significance to develop a simple, atom-economical, functional group-compatible, and highly efficient method for end-functionalizing polyoxazolines, and to prepare end-functionalized polyoxazolines with excellent end-group stability. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing end-functionalized polyoxazoline.

[0006] The technical solution adopted in this invention is:

[0007] A method for preparing end-functionalized polyoxazoline includes the following steps: mixing a weak Brønsted acid initiator, an ion exchange catalyst and an oxazoline monomer to carry out a cationic ring-opening polymerization reaction to obtain end-functionalized polyoxazoline.

[0008] Preferably, the molar ratio of the weak Brønsted acid initiator, the ion exchange catalyst, and the oxazoline monomer is 1:0.01 to 10:10 to 1000.

[0009] More preferably, the molar ratio of the weak Brønsted acid initiator, the ion exchange catalyst, and the oxazoline monomer is 1:0.05-5:20-100.

[0010] Preferably, the weak Brønsted acid initiator is at least one of the following: aromatic carboxylic acid weak Brønsted acid initiators, aliphatic carboxylic acid weak Brønsted acid initiators, thiocarboxylic acid weak Brønsted acid initiators, organophosphate weak Brønsted acid initiators, and amino acid weak Brønsted acid initiators.

[0011] Preferably, the aromatic carboxylic acid weak Brønsted acid initiator is at least one of benzoic acid, benzoic acid with a substituent group on the benzene ring, polycarboxylic aromatic acid, fused-ring carboxylic acid, polyphenyl carboxylic acid, and heterocyclic carboxylic acid.

[0012] Preferably, the substituent group in the benzoic acid containing a substituent group on the benzene ring is at least one of the following C1-C6 alkyl, cyano, acetyl, azophenyl, dimethylamino, methylthio, hydroxyl, halogen, formyl, vinyl, ethynyl, borate ester, benzyloxycarbonyl-protected amino, tert-butoxycarbonyl-protected amino, hydroxymethyl, and hydroxyethyl.

[0013] More preferably, the aromatic carboxylic acid weak Brønsted acid initiator is at least one of the following compounds:

[0014]

[0015] Preferably, the aliphatic carboxylic acid-based weak Brønsted acid initiator is C1-C6. 20 Aliphatic carboxylic acids.

[0016] More preferably, the aliphatic carboxylic acid weak Brønsted acid initiator is at least one of the following compounds:

[0017]

[0018] Preferably, the thiocarboxylic acid weak Brønsted acid initiator is at least one of thiofatty acids and thiobenzoic acid.

[0019] More preferably, the thiocarboxylic acid-based weak Brønsted acid initiator is at least one of the following compounds:

[0020]

[0021] Preferably, the organophosphate weak Brønsted acid initiator is at least one of R-PO(OH)2 and R1R2PO(OH), wherein R, R1, and R2 are independently C1 to C2. 18 One of the following: alkyl, phenyl, C1-C6 alkyl-substituted phenyl, methoxy-substituted phenyl, methylthio-substituted phenyl, halogen-substituted phenyl, and heterocyclic group.

[0022] Preferably, the amino acid-based weak Brønsted acid initiator is at least one of the following: an amino acid whose amino group is protected by a Cbz group, an amino acid whose amino group is protected by a Boc group, or an amino acid whose amino group is protected by an Fmoc group.

[0023] More preferably, the amino acid-based weak Brønsted acid initiator is at least one of the following compounds:

[0024]

[0025] Preferably, the ion exchange catalyst is at least one of sulfonylimide salt catalysts, organic ionic liquid catalysts, borate catalysts, sulfonate catalysts, phosphate catalysts, halide salt catalysts, and sulfate catalysts.

[0026] Preferably, the general chemical formula of the sulfonylimide salt catalyst is [M x+ [(RfSO2)2N] y- In the formula, M x+ For Li + Na + K + Ag + Zn 2+ Mg 2+ Ca 2+ One of them, Rf is one of halogen or perfluoroalkyl, and y is 1 or 2.

[0027] Preferably, the general chemical formula of the organic ionic liquid catalyst is [Cat + ][An - In the formula, Cat + It is one of imidazolium and pyrrolidineonium, An - BF4 - PF6 - (CF3SO2)2N - One of them.

[0028] Preferably, the borate catalyst has a general chemical formula of [M][BF4], [M][B(C6F5)4], or [M][B(C2O4)2], where M is one of an alkali metal cation, an alkaline earth metal cation, a transition metal cation, or an organic cation.

[0029] Preferably, the general chemical formula of the sulfonate catalyst is [M][RSO3], where M is one of alkali metal cations, alkaline earth metal cations, transition metal cations, and organic cations, and R is one of alkyl and aryl groups.

[0030] Preferably, the phosphate catalyst has the general chemical formula [M]. x [PO4] y In the formula, M is one of the following: alkali metal cation, alkaline earth metal cation, transition metal cation, and organic cation; x is an integer from 1 to 3; and y is an integer from 1 to 3.

[0031] Preferably, the general chemical formula of the halide salt catalyst is [M]X n In the formula, M is one of the following: alkali metal cation, alkaline earth metal cation, transition metal cation, and organic cation; X is a halogen; and n is an integer from 1 to 3.

[0032] Preferably, the cation in the sulfate catalyst is one of the following: alkali metal cation, alkaline earth metal cation, transition metal cation, or organic cation.

[0033] Preferably, the oxazoline monomer is 2-oxazoline, containing C1 to C2 at the 2-position. 13 At least one of the following: 2-oxazoline, 2-isopropyl-2-oxazoline, 2-isobutyl-2-oxazoline, 2-tert-butyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-cyclohexyl-2-oxazoline, 2-phenyl-2-oxazoline, 2-(4-methylphenyl)-2-oxazoline, 2-(4-methoxyphenyl)-2-oxazoline, 2-(4-chlorophenyl)-2-oxazoline, 2-(4-nitrophenyl)-2-oxazoline, 2-methoxymethyl-2-oxazoline, 2-trichloromethyl-2-oxazoline, and 2,2'-bis(2-oxazoline).

[0034] Note: The structural formula of the oxazoline monomer is as follows:

[0035]

[0036] Preferably, the cationic ring-opening polymerization reaction is carried out at a temperature of 0℃ to 200℃ for a reaction time of 0.5h to 300h.

[0037] More preferably, the cationic ring-opening polymerization reaction is carried out at a temperature of 140℃ to 180℃ for a reaction time of 20h to 50h.

[0038] Preferably, the cationic ring-opening polymerization reaction is carried out in a nitrogen atmosphere or an argon atmosphere.

[0039] Preferably, the weak Brønsted acid initiator, ion exchange catalyst, and oxazoline monomer are dispersed in a solvent to carry out a cationic ring-opening polymerization reaction.

[0040] Preferably, the initial concentration of the oxazoline monomer in the cationic ring-opening polymerization system is 0.5 mol / L to 10.6 mol / L.

[0041] Preferably, the solvent is at least one selected from γ-butyrolactone, γ-butyrolactone with an alkyl substituent at the γ-position (C1-C8), dichloromethane, chloroform, toluene, tetrahydrofuran, 2-methyltetrahydrofuran, chlorobenzene, acetonitrile, sulfolane, ethyl acetate, propylene carbonate, ethyl 3-phenylpropionate, n-butyl acetate, dimethyl sulfoxide, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0042] More preferably, the solvent is at least one of γ-butyrolactone and γ-butyrolactone containing an alkyl substituent at the γ position (C1-C8).

[0043] The beneficial effects of this invention are: the preparation method of end-functionalized polyoxazoline of this invention has the advantages of simple operation process, low equipment requirements, high atom economy, wide range of functional group compatibility, high functionalization efficiency and low cost. Moreover, the initiator used, weak Brønsted acid, has a high degree of commercialization, diverse structure and wide source. Finally, end-functionalized polyoxazoline with controllable molecular weight, narrow molecular weight distribution, tunable topology and tunable performance can be prepared.

[0044] Specifically:

[0045] 1) This invention innovatively introduces an ion exchange catalyst into the cationic ring-opening polymerization system of oxazoline, achieving a technological breakthrough for the first time in using weak Brønsted acids as highly efficient initiators. The ion exchange mechanism mediated by the ion exchange catalyst effectively overcomes the kinetic barrier of insufficient leaving ability of weak acid anions. It expands the selection range of initiators from traditional strong acid initiators and electrophilic initiators to a highly commercialized compound library of weak Brønsted acid compounds with multiple functional groups, diverse structures (containing tens of thousands of optional structures). This provides a brand-new molecular design platform for the precise construction of end-functionalized polyoxazoline materials, and is particularly suitable for the preparation of functional polymer materials with specific surface properties or bioactivity.

[0046] 2) This invention is the first to achieve a one-step in-situ synthesis of end-functionalized polyoxazoline using a catalytic system. Compared with traditional synthesis methods (traditional processes mainly use functionalized initiator initiation or functionalized reagent end-capping methods, the former is limited by the difficulty of synthesizing functionalized initiators and the degree of commercialization, while the latter has problems such as complex post-polymerization modification steps and excessive use of end-capping agents), this method has a breakthrough improvement, as follows: This method innovatively constructs an ion exchange catalytic polymerization system and uses commercially available and highly functionalized weak Brønsted acid as an initiator, realizing the simultaneous occurrence of polymerization reaction and end-functionalization. Only a single operation unit is needed to obtain the target product. This not only overcomes the multi-step operation defects of traditional processes, but also achieves significant improvements in reaction efficiency and atom economy, thus providing a new technical path for the large-scale preparation of end-functionalized polyoxazoline.

[0047] 3) The end-functionalized polyoxazoline prepared by this invention has a quantitative end-functionalization efficiency (>99%) and excellent functional group fidelity. The system of this invention effectively avoids the side reaction between the polymer end group and the catalyst counterion through the synergistic effect of the highly leaving active catalyst counterion and the highly stable weak Brønsted acid covalent bond, thus ensuring the integrity of the end group structure. This unique chemical stability enables the functionalized polymer to maintain structural stability under harsh application conditions, which greatly expands the application range of the material.

[0048] 4) This invention innovatively uses green solvents γ-butyrolactone and γ-butyrolactone with C1-C8 alkyl substituents at the γ-position as the reaction medium for the cationic ring-opening polymerization of oxazoline. This green solvent has the characteristics of high polarity, high boiling point, high chemical stability, low volatility, non-toxicity and good biocompatibility. In this ion exchange catalytic system, the green solvent system can promote the dynamic equilibrium of ion exchange between the catalyst and the counterion at the end of the active chain under high temperature conditions through a unique solvation effect, so as to achieve a controllable chain growth process. Under low temperature conditions, the solvation effect weakens, resulting in the nucleophilic termination of the active center by the counterion, forming a stable covalent end group structure. This is a characteristic that traditional solvent systems do not have. It not only significantly improves the safety and environmental friendliness of the polymerization process, but also provides a sustainable technology platform for constructing polyoxazoline materials with precise and controllable end group functionalization.

[0049] 5) By precisely controlling the stoichiometric ratio of the initiator and the catalyst, this invention can effectively control the kinetics of the cationic ring-opening polymerization of oxazoline monomers. By optimizing the concentration and distribution of active centers, the activation energy barrier of the polymerization reaction is significantly reduced while ensuring a high monomer conversion rate, thereby achieving a reduction in reaction temperature and an increase in polymerization rate.

[0050] 6) The catalytic polymerization system used in this invention has high catalytic activity, exhibiting the activity characteristics of cationic polymerization. The product molecular weight is controllable and has a narrow distribution and a wide molecular weight range. It solves the problems of side reactions such as chain coupling that exist in traditional cationic ring-opening polymerization methods, and there are no problems such as catalyst metal poisoning (no heavy metal pollution). The polymer products obtained have been tested and confirmed to be non-cytotoxic. The products can be efficiently purified by mild methods such as repeated precipitation, ion exchange resin adsorption, or dialysis. This characteristic makes it particularly suitable for the industrial production of biomedical polymer materials.

[0051] 7) This invention can obtain a series of end-functionalized homopolymers / copolymers with different structures and functions by using oxazoline monomers with different side groups. They can be flexibly designed according to application scenarios to meet different needs.

[0052] 8) This invention uses structurally tunable weak Brønsted acid as an initiator to construct multiple chain growth sites through an active cationic ring-opening polymerization mechanism. This allows for precise control of the topological structure of polyoxazoline polymers, thereby enabling the design and preparation of various topological configurations such as single-arm linear, double-arm linear, star-shaped, dendritic, and hyperbranched polymers. Attached Figure Description

[0053] Figure 1 This is a SEC chromatogram of the purified product from Example 1.

[0054] Figure 2 The crude product in Example 1 1 H NMR spectrum.

[0055] Figure 3 The purified product of Example 1 1 H NMR spectrum.

[0056] Figure 4 The image shows a MALDI-TOF MS chromatogram of the purified product from Example 1.

[0057] Figure 5 This is a SEC chromatogram of the purified product from Example 2.

[0058] Figure 6 The crude product in Example 2 1 H NMR spectrum.

[0059] Figure 7 The purified product of Example 2 1 H NMR spectrum.

[0060] Figure 8 The image shows a MALDI-TOF MS plot of the purified product from Example 2.

[0061] Figure 9 This is a SEC chromatogram of the purified product from Example 10.

[0062] Figure 10 The crude product in Example 10 1 H NMR spectrum.

[0063] Figure 11 The purified product of Example 10 1 H NMR spectrum.

[0064] Figure 12 The image shows a MALDI-TOF MS plot of the purified product from Example 10.

[0065] Figure 13 The graph shows the aggregation-induced emission of the end-functionalized polyoxazoline in Example 11 in water-tetrahydrofuran mixed solutions of different volume fractions.

[0066] Figure 14 The photoluminescence emission spectra of the end-functionalized polyoxazoline in Example 11 in water-tetrahydrofuran mixed solutions of different volume fractions are shown.

[0067] Figure 15 This is a SEC chromatogram of the purified product from Example 15.

[0068] Figure 16 The purified product of Example 15 1 H NMR spectrum.

[0069] Figure 17 The image shows a MALDI-TOF MS plot of the purified product from Example 15. Detailed Implementation

[0070] The present invention will be further explained and described below with reference to specific embodiments.

[0071] The conversion rate and polymer structure characteristics of the oxazoline monomer were measured using a Bruker AV400 liquid nuclear magnetic resonance spectrometer with deuterated chloroform as the solvent.

[0072] Molecular weight and molecular weight distribution (D M The tests were performed using an Agilent 1260 Infinity volume exclusion chromatograph. The mobile phase was N,N-dimethylformamide, the column temperature was 50℃, and the flow rate was 1 mL / min. A series of polymethyl methacrylate standard samples were used to create a calibration curve.

[0073] The structural formulas and abbreviations of the main raw materials in Examples 1-22 are as follows:

[0074] Example 1:

[0075] A method for preparing end-functionalized polyoxazoline, comprising the following steps:

[0076] In a nitrogen atmosphere, 1 mmol of benzoic acid (BA), 0.1 mmol of lithium bis(trifluorosulfonyl)imide (LiTFSI), 50 mmol of 2-ethyl-2-oxazoline (EtOx) and 7.8 mL of γ-valerol were added to a glass reactor (dried at 200 °C and then brought back to room temperature). The glass reactor was sealed, and a magnetic stirrer was turned on. The reaction was carried out at 180 °C for 48 h to obtain the initial product (pale yellow transparent viscous liquid). The reaction was then terminated by cooling the glass reactor with an ice-water bath. The initial product was diluted with chloroform, and then ether was added to precipitate it. The solid was collected and dried in a vacuum oven at 50 °C for 12 h to obtain the purified product.

[0077] Performance testing:

[0078] The SEC (exclusion chromatogram) of the purified product in this embodiment is shown below. Figure 1 As shown, the crude product 1 H NMR spectrum as shown Figure 2 As shown, the purified product 1 H NMR spectrum as shown Figure 3 As shown, the MALDI-TOF MS (matrix-assisted laser desorption / ionization-time-of-flight mass spectrometry) chromatogram of the purified product is as follows: Figure 4 As shown.

[0079] Depend on Figures 1-4 It can be seen that the conversion rate of EtOx in this embodiment is 81%; for 1 Analysis of the H NMR spectrum and MALDI-TOF MS plot fully demonstrates that the product structure is well-defined and the functionalization degree of the end groups is 100%. The number average molecular weight measured by SEC is 8.2 kg / mol (the theoretical number average molecular weight calculated by the feed ratio and conversion rate is 4.1 kg / mol), and the molecular weight distribution is 1.17.

[0080] In summary, the structural formula of the end-functionalized polyoxazoline synthesized in this embodiment is as follows:

[0081]

[0082] Example 2:

[0083] A method for preparing end-functionalized polyoxazoline, comprising the following steps:

[0084] In a nitrogen atmosphere, 1 mmol of 4-cyanobenzoic acid (CBA), 0.1 mmol of lithium bis(trifluorosulfonyl)imide (LiTFSI), 50 mmol of 2-ethyl-2-oxazoline (EtOx) and 7.8 mL of γ-valerol were added to a glass reactor (dried at 200 °C and then brought back to room temperature). The glass reactor was sealed, and a magnetic stirrer was turned on. The reaction was carried out at 180 °C for 24 h to obtain the initial product (pale yellow transparent viscous liquid). The reaction was then terminated by cooling the glass reactor with an ice-water bath. The initial product was diluted with chloroform, and then ether was added to precipitate it. The solid was collected and dried in a vacuum oven at 50 °C for 12 h to obtain the purified product.

[0085] Performance testing:

[0086] The SEC chromatogram of the purified product in this embodiment is as follows: Figure 5 As shown, the crude product 1 H NMR spectrum as shown Figure 6 As shown, the purified product 1 H NMR spectrum as shown Figure 7 As shown, the MALDI-TOF MS plot is as follows: Figure 8 As shown.

[0087] Depend on Figures 5-8 It can be seen that the conversion rate of EtOx in this embodiment is 100%; for 1 Analysis of the H NMR spectrum and MALDI-TOF MS plot fully demonstrates that the product structure is well-defined and the functionalization degree of the end groups is 100%. The number-average molecular weight measured by SEC is 9.3 kg / mol (the theoretical number-average molecular weight calculated based on the feed ratio and conversion rate is 5.1 kg / mol), and the molecular weight distribution is 1.17.

[0088] In summary, the structural formula of the end-functionalized polyoxazoline synthesized in this embodiment is as follows:

[0089]

[0090] Example 3:

[0091] A method for preparing end-functionalized polyoxazoline, comprising the following steps:

[0092] In a nitrogen atmosphere, 1 mmol of 4-acetylbenzoic acid (AcBA), 0.1 mmol of lithium bis(trifluorosulfonyl)imide (LiTFSI), 50 mmol of 2-ethyl-2-oxazoline (EtOx) and 7.8 mL of γ-valerol were added to a glass reactor (dried at 200 °C and then brought back to room temperature). The glass reactor was sealed, and a magnetic stirrer was turned on. The reaction was carried out at 180 °C for 48 h to obtain the initial product (pale yellow transparent viscous liquid). The reaction was then terminated by cooling the glass reactor with an ice-water bath. The initial product was diluted with chloroform, and then ether was added to precipitate it. The solid was collected and dried in a vacuum oven at 50 °C for 12 h to obtain the purified product.

[0093] After testing (using the same method as in Example 1), the conversion rate of EtOx in this example was 88%; 1 Analysis of the H NMR spectrum and MALDI-TOF MS plot fully demonstrates that the product structure is well-defined and the functionalization degree of the end groups is 100%. The number average molecular weight measured by SEC is 8.8 kg / mol (the theoretical number average molecular weight calculated based on the feed ratio and conversion rate is 4.5 kg / mol), and the molecular weight distribution is 1.17.

[0094] In summary, the structural formula of the end-functionalized polyoxazoline synthesized in this embodiment is as follows:

[0095]

[0096] Example 4:

[0097] A method for preparing end-functionalized polyoxazoline, comprising the following steps:

[0098] In a nitrogen atmosphere, 1 mmol of azobenzene-4-carboxylic acid (AzBA), 0.1 mmol of lithium bis(trifluorosulfonyl)imide (LiTFSI), 50 mmol of 2-ethyl-2-oxazoline (EtOx) and 7.8 mL of γ-valerol were added to a glass reactor (dried at 200 °C and then brought back to room temperature). The glass reactor was sealed, and a magnetic stirrer was turned on. The reaction was carried out at 180 °C for 48 h to obtain the initial product (pale yellow transparent viscous liquid). The reaction was then terminated by cooling the glass reactor with an ice-water bath. The initial product was diluted with chloroform, and then ether was added to precipitate it. The solid was collected and dried in a vacuum oven at 50 °C for 12 h to obtain the purified product.

[0099] According to the test (test method is the same as in Example 1), the conversion rate of EtOx in this example is 79%; 1Analysis of the H NMR spectrum and MALDI-TOF MS plot fully demonstrates that the product structure is well-defined and the functionalization degree of the end groups is 100%. The number-average molecular weight measured by SEC is 8.4 kg / mol (the theoretical number-average molecular weight calculated based on the feed ratio and conversion rate is 4.1 kg / mol), and the molecular weight distribution is 1.20.

[0100] In summary, the structural formula of the end-functionalized polyoxazoline synthesized in this embodiment is as follows:

[0101]

[0102] Example 5:

[0103] A method for preparing end-functionalized polyoxazoline, comprising the following steps:

[0104] In a nitrogen atmosphere, 1 mmol of 4-dimethylaminobenzoic acid (DMABA), 0.2 mmol of lithium bis(trifluorosulfonyl)imide (LiTFSI), 30 mmol of 2-ethyl-2-oxazoline (EtOx) and 7.8 mL of γ-valerol were added to a glass reactor (dried at 200 °C and then brought back to room temperature). The glass reactor was sealed, and a magnetic stirrer was turned on. The reaction was carried out at 180 °C for 48 h to obtain the initial product (pale yellow transparent viscous liquid). The reaction was then terminated by cooling the glass reactor with an ice-water bath. The initial product was diluted with chloroform, and then ether was added to precipitate it. The solid was collected and dried in a vacuum oven at 50 °C for 12 h to obtain the purified product.

[0105] After testing (using the same method as in Example 1), the conversion rate of EtOx in this example was 100%; 1 Analysis of the H NMR spectrum and MALDI-TOF MS plot fully demonstrates that the product structure is well-defined and the functionalization degree of the end groups is 100%. The number-average molecular weight measured by SEC is 8.6 kg / mol (the theoretical number-average molecular weight calculated based on the feed ratio and conversion rate is 3.1 kg / mol), and the molecular weight distribution is 1.48.

[0106] In summary, the structural formula of the end-functionalized polyoxazoline synthesized in this embodiment is as follows:

[0107]

[0108] Example 6:

[0109] A method for preparing end-functionalized polyoxazoline, comprising the following steps:

[0110] In a nitrogen atmosphere, 1 mmol of 3,4-dimethoxybenzoic acid (DMOBA), 0.1 mmol of lithium bis(trifluorosulfonyl)imide (LiTFSI), 50 mmol of 2-ethyl-2-oxazoline (EtOx) and 7.8 mL of γ-valerol were added to a glass reactor (dried at 200 °C and then brought back to room temperature). The glass reactor was sealed, and a magnetic stirrer was turned on. The reaction was carried out at 180 °C for 48 h to obtain the initial product (pale yellow transparent viscous liquid). The reaction was then terminated by cooling the glass reactor with an ice-water bath. The initial product was diluted with chloroform, and then ether was added to precipitate it. The solid was collected and dried in a vacuum oven at 50 °C for 12 h to obtain the purified product.

[0111] According to the test (test method is the same as in Example 1), the conversion rate of EtOx in this example is 45%; 1 Analysis of the H NMR spectrum and MALDI-TOF MS plot fully demonstrates that the product structure is well-defined and the functionalization degree of the end groups is 100%. The number-average molecular weight measured by SEC is 5.1 kg / mol (the theoretical number-average molecular weight calculated based on the feed ratio and conversion rate is 2.4 kg / mol), and the molecular weight distribution is 1.13.

[0112] In summary, the structural formula of the end-functionalized polyoxazoline synthesized in this embodiment is as follows:

[0113]

[0114] Example 7:

[0115] A method for preparing end-functionalized polyoxazoline, comprising the following steps:

[0116] In a nitrogen atmosphere, 1 mmol of 4-methylthiobenzoic acid (MTBA), 0.1 mmol of lithium bis(trifluorosulfonyl)imide (LiTFSI), 50 mmol of 2-ethyl-2-oxazoline (EtOx) and 7.8 mL of γ-valerol were added to a glass reactor (dried at 200 °C and then brought back to room temperature). The glass reactor was sealed, and a magnetic stirrer was turned on. The reaction was carried out at 180 °C for 48 h to obtain the initial product (pale yellow transparent viscous liquid). The reaction was then terminated by cooling the glass reactor with an ice-water bath. The initial product was diluted with chloroform, and then ether was added to precipitate it. The solid was collected and dried in a vacuum oven at 50 °C for 12 h to obtain the purified product.

[0117] According to the test (test method is the same as in Example 1), the conversion rate of EtOx in this example is 84%; 1Analysis of the H NMR spectrum and MALDI-TOF MS plot fully demonstrates that the product structure is well-defined and the functionalization degree of the end groups is 100%. The number-average molecular weight measured by SEC is 9.2 kg / mol (the theoretical number-average molecular weight calculated based on the feed ratio and conversion rate is 4.4 kg / mol), and the molecular weight distribution is 1.15.

[0118] In summary, the structural formula of the end-functionalized polyoxazoline synthesized in this embodiment is as follows:

[0119]

[0120] Example 8:

[0121] A method for preparing end-functionalized polyoxazoline, comprising the following steps:

[0122] In a nitrogen atmosphere, 1 mmol of salicylic acid (SA), 0.1 mmol of lithium bis(trifluorosulfonyl)imide (LiTFSI), 50 mmol of 2-ethyl-2-oxazoline (EtOx) and 7.8 mL of γ-valerol were added to a glass reactor (dried at 200 °C and then brought back to room temperature). The glass reactor was sealed, and a magnetic stirrer was turned on. The reaction was carried out at 180 °C for 48 h to obtain the initial product (pale yellow transparent viscous liquid). The reaction was then terminated by cooling the glass reactor with an ice-water bath. The initial product was diluted with chloroform and then precipitated with diethyl ether. The solid was collected and dried in a vacuum oven at 50 °C for 12 h to obtain the purified product.

[0123] After testing (using the same method as in Example 1), the conversion rate of EtOx in this example was 90%; 1 Analysis of the H NMR spectrum and MALDI-TOF MS plot fully demonstrates that the product structure is well-defined and the functionalization degree of the end groups is 100%. The number average molecular weight measured by SEC is 8.8 kg / mol (the theoretical number average molecular weight calculated based on the feed ratio and conversion rate is 4.6 kg / mol), and the molecular weight distribution is 1.28.

[0124] In summary, the structural formula of the end-functionalized polyoxazoline synthesized in this embodiment is as follows:

[0125]

[0126] Example 9:

[0127] A method for preparing end-functionalized polyoxazoline, comprising the following steps:

[0128] In a nitrogen atmosphere, 1 mmol of 9-anthracarboxylic acid (ACA), 0.1 mmol of lithium bis(trifluorosulfonyl)imide (LiTFSI), 50 mmol of 2-ethyl-2-oxazoline (EtOx) and 7.8 mL of γ-valerol were added to a glass reactor (dried at 200 °C and then brought back to room temperature). The glass reactor was sealed, and a magnetic stirrer was turned on. The reaction was carried out at 180 °C for 48 h to obtain the initial product (pale yellow transparent viscous liquid). The reaction was then terminated by cooling the glass reactor with an ice-water bath. The initial product was diluted with chloroform, and then ether was added to precipitate it. The solid was collected and dried in a vacuum oven at 50 °C for 12 h to obtain the purified product.

[0129] After testing (using the same method as in Example 1), the conversion rate of EtOx in this example was 87%; 1 Analysis of the H NMR spectrum and MALDI-TOF MS plot fully demonstrates that the product structure is well-defined and the functionalization degree of the end groups is 100%. The number average molecular weight measured by SEC is 8.7 kg / mol (the theoretical number average molecular weight calculated based on the feed ratio and conversion rate is 4.5 kg / mol), and the molecular weight distribution is 1.18.

[0130] In summary, the structural formula of the end-functionalized polyoxazoline synthesized in this embodiment is as follows:

[0131]

[0132] Example 10:

[0133] A method for preparing end-functionalized polyoxazoline, comprising the following steps:

[0134] In a nitrogen atmosphere, 1 mmol of 1-pyrene carboxylic acid (PCA), 0.1 mmol of lithium bis(trifluorosulfonyl)imide (LiTFSI), 50 mmol of 2-ethyl-2-oxazoline (EtOx) and 7.8 mL of γ-valerol were added to a glass reactor (dried at 200 °C and then brought back to room temperature). The glass reactor was sealed, and a magnetic stirrer was turned on. The reaction was carried out at 180 °C for 48 h to obtain the initial product (pale yellow transparent viscous liquid). The reaction was then terminated by cooling the glass reactor with an ice-water bath. The initial product was diluted with chloroform, and then ether was added to precipitate it. The solid was collected and dried in a vacuum oven at 50 °C for 12 h to obtain the purified product.

[0135] Performance testing:

[0136] The SEC chromatogram of the purified product in this embodiment is as follows: Figure 9 As shown, the crude product 1 H NMR spectrum as shown Figure 10 As shown, the purified product 1H NMR spectrum as shown Figure 11 As shown, the MALDI-TOF MS chromatogram of the purified product is as follows. Figure 12 As shown.

[0137] Depend on Figures 9-12 It can be seen that the conversion rate of EtOx in this embodiment is 82%; for 1 Analysis of the H NMR spectrum and MALDI-TOF MS plot fully demonstrates that the product structure is well-defined and the functionalization degree of the end groups is 100%. The number-average molecular weight measured by SEC is 7.6 kg / mol (the theoretical number-average molecular weight calculated based on the feed ratio and conversion rate is 4.3 kg / mol), and the molecular weight distribution is 1.20.

[0138] In summary, the structural formula of the end-functionalized polyoxazoline synthesized in this embodiment is as follows:

[0139]

[0140] Example 11:

[0141] A method for preparing end-functionalized polyoxazoline, comprising the following steps:

[0142] In a nitrogen atmosphere, 1 mmol of 1-(4-carboxyphenyl)-1,2,2-triphenylethylene (TPEA), 0.1 mmol of lithium bis(trifluorosulfonyl)imide (LiTFSI), 50 mmol of 2-ethyl-2-oxazoline (EtOx) and 7.8 mL of γ-valerol were added to a glass reactor (dried at 200 °C and then brought back to room temperature). The glass reactor was sealed, and a magnetic stirrer was turned on. The reaction was carried out at 180 °C for 48 h to obtain the initial product (pale yellow transparent viscous liquid). The reaction was then terminated by cooling the glass reactor with an ice-water bath. The initial product was diluted with chloroform, and then ether was added to precipitate it. The solid was collected and dried in a vacuum oven at 50 °C for 12 h to obtain the purified product.

[0143] After testing (using the same method as in Example 1), the conversion rate of EtOx in this example was 85%; 1 Analysis of the H NMR spectrum and MALDI-TOF MS plot fully demonstrates that the product structure is well-defined and the functionalization degree of the end groups is 100%. The number-average molecular weight measured by SEC is 9.3 kg / mol (the theoretical number-average molecular weight calculated based on the feed ratio and conversion rate is 4.6 kg / mol), and the molecular weight distribution is 1.14.

[0144] In summary, the structural formula of the end-functionalized polyoxazoline synthesized in this embodiment is as follows:

[0145]

[0146] Aggregation-induced emission property test:

[0147] The aggregation-induced emission (AIE) effect (physical image) of the end-functionalized polyoxazoline in this embodiment in water-tetrahydrofuran mixed solutions of different concentrations (water volume fractions of 0%, 40%, 60%, 80%, 90%, 95%, and 100% respectively) is shown in the image. Figure 13 As shown, the photoluminescence emission spectrum is as follows: Figure 14 As shown.

[0148] Depend on Figure 13 and Figure 14 It can be known that:

[0149] 1) When the solvent is pure tetrahydrofuran (THF), the fluorescence intensity is close to zero and there is no visible aggregation-induced emission (AIE) phenomenon. The reason is that the polyoxazoline with tetraphenylethylene end group is completely dissolved into a single molecule state. The excited state energy is dissipated in a non-radiative manner through intramolecular motion, resulting in fluorescence quenching.

[0150] 2) As the proportion of water in the mixed solution increases, especially when the volume fraction of water exceeds 90%, the fluorescence intensity is significantly enhanced and exhibits obvious AIE characteristics. The reason is that water, as a poor solvent, promotes the self-assembly of polymer molecules to form aggregates. The steric hindrance inhibits the rotation of the benzene ring, so that energy can only be released in the form of radiation, thereby greatly improving the fluorescence intensity.

[0151] In summary, this embodiment successfully obtained a stable polyoxazoline with a high degree of functionalization at the end groups.

[0152] Example 12:

[0153] A method for preparing end-functionalized polyoxazoline, comprising the following steps:

[0154] In a nitrogen atmosphere, 1 mmol of 2-furanic acid (FA), 0.1 mmol of lithium bis(trifluorosulfonyl)imide (LiTFSI), 50 mmol of 2-ethyl-2-oxazoline (EtOx) and 7.8 mL of γ-valerol were added to a glass reactor (dried at 200 °C and then brought back to room temperature). The glass reactor was sealed, and a magnetic stirrer was turned on. The reaction was carried out at 180 °C for 48 h to obtain the initial product (pale yellow transparent viscous liquid). The reaction was then terminated by cooling the glass reactor with an ice-water bath. The initial product was diluted with chloroform, and then ether was added to precipitate it. The solid was collected and dried in a vacuum oven at 50 °C for 12 h to obtain the purified product.

[0155] After testing (using the same method as in Example 1), the conversion rate of EtOx in this example was 91%; 1Analysis of the H NMR spectrum and MALDI-TOF MS plot fully demonstrates that the product structure is well-defined and the functionalization degree of the end groups is 100%. The number-average molecular weight measured by SEC is 9.8 kg / mol (the theoretical number-average molecular weight calculated by the feed ratio and conversion rate is 4.6 kg / mol), and the molecular weight distribution is 1.15.

[0156] In summary, the structural formula of the end-functionalized polyoxazoline synthesized in this embodiment is as follows:

[0157]

[0158] Example 13:

[0159] A method for preparing end-functionalized polyoxazoline, comprising the following steps:

[0160] In a nitrogen atmosphere, 1 mmol of 2-thiophenecarboxylic acid (TCA), 0.1 mmol of lithium bis(trifluorosulfonyl)imide (LiTFSI), 50 mmol of 2-ethyl-2-oxazoline (EtOx) and 7.8 mL of γ-valerol were added to a glass reactor (dried at 200 °C and then brought back to room temperature). The glass reactor was sealed, and a magnetic stirrer was turned on. The reaction was carried out at 180 °C for 48 h to obtain the initial product (pale yellow transparent viscous liquid). The reaction was then terminated by cooling the glass reactor with an ice-water bath. The initial product was diluted with chloroform, and then ether was added to precipitate it. The solid was collected and dried in a vacuum oven at 50 °C for 12 h to obtain the purified product.

[0161] After testing (using the same method as in Example 1), the conversion rate of EtOx in this example was 81%; 1 Analysis of the H NMR spectrum and MALDI-TOF MS plot fully demonstrates that the product structure is well-defined and the functionalization degree of the end groups is 100%. The number-average molecular weight measured by SEC is 9.3 kg / mol (the theoretical number-average molecular weight calculated by the feed ratio and conversion rate is 4.1 kg / mol), and the molecular weight distribution is 1.14.

[0162] In summary, the structural formula of the end-functionalized polyoxazoline synthesized in this embodiment is as follows:

[0163]

[0164] Example 14:

[0165] A method for preparing end-functionalized polyoxazoline, comprising the following steps:

[0166] In a nitrogen atmosphere, 1 mmol of pyrrole-2-carboxylic acid (PyCA), 0.1 mmol of lithium bis(trifluorosulfonyl)imide (LiTFSI), 50 mmol of 2-ethyl-2-oxazoline (EtOx) and 7.8 mL of γ-valerol were added to a glass reactor (dried at 200 °C and then brought back to room temperature). The glass reactor was sealed, and a magnetic stirrer was turned on. The reaction was carried out at 180 °C for 48 h to obtain the initial product (pale yellow transparent viscous liquid). The reaction was then terminated by cooling the glass reactor with an ice-water bath. The initial product was diluted with chloroform, and then ether was added to precipitate it. The solid was collected and dried in a vacuum oven at 50 °C for 12 h to obtain the purified product.

[0167] After testing (using the same method as in Example 1), the conversion rate of EtOx in this example was 98%; 1 Analysis of the H NMR spectrum and MALDI-TOF MS plot fully demonstrates that the product structure is well-defined and the functionalization degree of the end groups is 100%. The number average molecular weight measured by SEC is 10.7 kg / mol (the theoretical number average molecular weight calculated based on the feed ratio and conversion rate is 5.0 kg / mol), and the molecular weight distribution is 1.19.

[0168] In summary, the structural formula of the end-functionalized polyoxazoline synthesized in this embodiment is as follows:

[0169]

[0170] Example 15:

[0171] A method for preparing end-functionalized polyoxazoline, comprising the following steps:

[0172] In a nitrogen atmosphere, 1 mmol of 2-ethylhexanoic acid (EHA), 0.1 mmol of lithium bis(trifluorosulfonyl)imide (LiTFSI), 50 mmol of 2-ethyl-2-oxazoline (EtOx) and 7.8 mL of γ-valerol were added to a glass reactor (dried at 200 °C and then brought back to room temperature). The glass reactor was sealed, and a magnetic stirrer was turned on. The reaction was carried out at 180 °C for 48 h to obtain the initial product (pale yellow transparent viscous liquid). The reaction was then terminated by cooling the glass reactor with an ice-water bath. The initial product was diluted with chloroform, and then ether was added to precipitate it. The solid was collected and dried in a vacuum oven at 50 °C for 12 h to obtain the purified product.

[0173] Performance testing:

[0174] The SEC chromatogram of the purified product in this embodiment is as follows: Figure 15 As shown, 1 H NMR spectrum as shown Figure 16 As shown, the MALDI-TOFMS image is as follows: Figure 17 As shown.

[0175] Depend on Figures 15-17 It can be seen that the conversion rate of EtOx in this embodiment is 32%; for 1 Analysis of the H NMR spectrum and MALDI-TOF MS plot fully demonstrates that the product structure is well-defined and the functionalization degree of the end groups is 100%. The number-average molecular weight measured by SEC is 4.8 kg / mol (the theoretical number-average molecular weight calculated by the feed ratio and conversion rate is 1.6 kg / mol), and the molecular weight distribution is 1.12.

[0176] In summary, the structural formula of the end-functionalized polyoxazoline synthesized in this embodiment is as follows:

[0177]

[0178] Example 16:

[0179] A method for preparing end-functionalized polyoxazoline, comprising the following steps:

[0180] In a nitrogen atmosphere, 1 mmol of benzoic acid (BA), 0.1 mmol of lithium bis(trifluorosulfonyl)imide (LiTFSI), 50 mmol of 2-methyl-2-oxazoline (MeOx) and 7.8 mL of γ-valerol were added to a glass reactor (dried at 200 °C and then brought back to room temperature). The glass reactor was sealed, and a magnetic stirrer was turned on. The reaction was carried out at 140 °C for 48 h to obtain the initial product (pale yellow transparent viscous liquid). The reaction was then terminated by cooling the glass reactor with an ice-water bath. The initial product was diluted with chloroform, and then ether was added to precipitate it. The solid was collected and dried in a vacuum oven at 50 °C for 12 h to obtain the purified product.

[0181] After testing (using the same method as in Example 1), the conversion rate of MeOx in this example was 61%; 1 Analysis of the H NMR spectrum and MALDI-TOF MS plot fully demonstrates that the product structure is well-defined and the functionalization degree of the end groups is 100%. The number average molecular weight measured by SEC is 7.5 kg / mol (the theoretical number average molecular weight calculated by the feed ratio and conversion rate is 2.6 kg / mol), and the molecular weight distribution is 1.24.

[0182] In summary, the structural formula of the end-functionalized polyoxazoline synthesized in this embodiment is as follows:

[0183]

[0184] Example 17:

[0185] A method for preparing end-functionalized polyoxazoline, comprising the following steps:

[0186] In a nitrogen atmosphere, 1 mmol of benzoic acid (BA), 0.2 mmol of lithium bis(trifluorosulfonyl)imide (LiTFSI), 30 mmol of 2-phenyl-2-oxazoline (PhOx) and 7.8 mL of γ-valerol were added to a glass reactor (dried at 200 °C and then brought back to room temperature). The glass reactor was sealed, and a magnetic stirrer was turned on. The reaction was carried out at 180 °C for 24 h to obtain the initial product (pale yellow transparent viscous liquid). The reaction was then terminated by cooling the glass reactor with an ice-water bath. The initial product was diluted with chloroform, and then ether was added to precipitate it. The solid was collected and dried in a vacuum oven at 50 °C for 12 h to obtain the purified product.

[0187] According to the test (test method is the same as in Example 1), the conversion rate of PhOx in this example is 12%; 1 Analysis of the H NMR spectrum and MALDI-TOF MS plot fully demonstrates that the product structure is well-defined and the functionalization degree of the end groups is 100%. The number average molecular weight measured by SEC is 2.2 kg / mol (the theoretical number average molecular weight calculated based on the feed ratio and conversion rate is 0.7 kg / mol), and the molecular weight distribution is 1.05.

[0188] In summary, the structural formula of the end-functionalized polyoxazoline synthesized in this embodiment is as follows:

[0189]

[0190] Example 18:

[0191] A method for preparing end-functionalized polyoxazoline, comprising the following steps:

[0192] In a nitrogen atmosphere, 1 mmol of Cbz-L-valine (Cbz-L-Valine), 0.1 mmol of lithium bis(trifluorosulfonyl)imide (LiTFSI), 50 mmol of 2-ethyl-2-oxazoline (EtOx) and 7.8 mL of γ-valactone were added to a glass reactor (dried at 200 °C and then returned to room temperature). The glass reactor was sealed, and a magnetic stirrer was turned on. The reaction was carried out at 140 °C for 48 h to obtain the initial product (pale yellow transparent viscous liquid). The reaction was then terminated by cooling the glass reactor with an ice-water bath. The initial product was diluted with chloroform, and then ether was added to precipitate it. The solid was collected and dried in a vacuum oven at 50 °C for 12 h to obtain the purified product.

[0193] After testing (using the same method as in Example 1), the conversion rate of EtOx in this example was 91%; 1Analysis of the H NMR spectrum and MALDI-TOF MS plot fully demonstrates that the product structure is well-defined and the functionalization degree of the end groups is 100%. The number-average molecular weight measured by SEC is 10.9 kg / mol (the theoretical number-average molecular weight calculated based on the feed ratio and conversion rate is 4.6 kg / mol), and the molecular weight distribution is 1.26.

[0194] In summary, the structural formula of the end-functionalized polyoxazoline synthesized in this embodiment is as follows:

[0195]

[0196] Example 19:

[0197] A method for preparing end-functionalized polyoxazoline, comprising the following steps:

[0198] In a nitrogen atmosphere, 1 mmol of diphenylphosphoric acid (DPPA), 0.1 mmol of lithium bis(trifluorosulfonyl)imide (LiTFSI), 50 mmol of 2-ethyl-2-oxazoline (EtOx) and 7.8 mL of γ-valerol were added to a glass reactor (dried at 200 °C and then brought back to room temperature). The glass reactor was sealed, and a magnetic stirrer was turned on. The reaction was carried out at 180 °C for 48 h to obtain the initial product (pale yellow transparent viscous liquid). The reaction was then terminated by cooling the glass reactor with an ice-water bath. The initial product was diluted with chloroform, and then ether was added to precipitate it. The solid was collected and dried in a vacuum oven at 50 °C for 12 h to obtain the purified product.

[0199] After testing (using the same method as in Example 1), the conversion rate of EtOx in this example was 100%; 1 Analysis of the H NMR spectrum and MALDI-TOF MS plot fully demonstrates that the product structure is well-defined and the functionalization degree of the end groups is 100%. The number-average molecular weight measured by SEC is 10.5 kg / mol (the theoretical number-average molecular weight calculated based on the feed ratio and conversion rate is 5.1 kg / mol), and the molecular weight distribution is 1.26.

[0200] In summary, the structural formula of the end-functionalized polyoxazoline synthesized in this embodiment is as follows:

[0201]

[0202] Example 20:

[0203] A method for preparing end-functionalized polyoxazoline, comprising the following steps:

[0204] In a nitrogen atmosphere, 1 mmol of benzoic acid (BA), 1 mmol of lithium iodide (LiI), 50 mmol of 2-ethyl-2-oxazoline (EtOx) and 7.8 mL of γ-valerol were added to a glass reactor (dried at 200 °C and then brought back to room temperature). The glass reactor was sealed, and a magnetic stirrer was turned on. The reaction was carried out at 140 °C for 48 h to obtain the initial product (pale yellow transparent viscous liquid). The reaction was then terminated by cooling the glass reactor with an ice-water bath. The initial product was diluted with chloroform and then precipitated with diethyl ether. The solid was collected and dried in a vacuum oven at 50 °C for 12 h to obtain the purified product.

[0205] According to the test (test method is the same as in Example 1), the conversion rate of EtOx in this example is 62%; 1 Analysis of the H NMR spectrum and MALDI-TOF MS plot fully demonstrates that the product structure is well-defined and the functionalization degree of the end groups is 100%. The number-average molecular weight measured by SEC is 6.3 kg / mol (the theoretical number-average molecular weight calculated based on the feed ratio and conversion rate is 3.1 kg / mol), and the molecular weight distribution is 1.26.

[0206] In summary, the structural formula of the end-functionalized polyoxazoline synthesized in this embodiment is as follows:

[0207]

[0208] Example 21:

[0209] A method for preparing end-functionalized polyoxazoline, comprising the following steps:

[0210] In a nitrogen atmosphere, 1 mmol of benzoic acid (BA), 1 mmol of lithium dodecyl sulfate (LDS), 50 mmol of 2-ethyl-2-oxazoline (EtOx) and 7.8 mL of γ-valerol were added to a glass reactor (dried at 200 °C and then brought back to room temperature). The glass reactor was sealed, and a magnetic stirrer was turned on. The reaction was carried out at 140 °C for 48 h to obtain the initial product (pale yellow transparent viscous liquid). The reaction was then terminated by cooling the glass reactor with an ice-water bath. The initial product was diluted with chloroform, and then ether was added to precipitate it. The solid was collected and dried in a vacuum oven at 50 °C for 12 h to obtain the purified product.

[0211] After testing (using the same method as in Example 1), the conversion rate of EtOx in this example was 95%; 1Analysis of the H NMR spectrum and MALDI-TOF MS plot fully demonstrates that the product structure is well-defined and the functionalization degree of the end groups is 100%. The number-average molecular weight measured by SEC is 9.9 kg / mol (the theoretical number-average molecular weight calculated based on the feed ratio and conversion rate is 4.7 kg / mol), and the molecular weight distribution is 1.30.

[0212] In summary, the structural formula of the end-functionalized polyoxazoline synthesized in this embodiment is as follows:

[0213]

[0214] Example 22:

[0215] A method for preparing end-functionalized polyoxazoline, comprising the following steps:

[0216] In a nitrogen atmosphere, 1 mmol of benzoic acid (BA), 1 mmol of sodium tetra(pentafluorophenyl)borate (NaBArF), 50 mmol of 2-ethyl-2-oxazoline (EtOx) and 7.8 mL of γ-valerol were added to a glass reactor (dried at 200 °C and then returned to room temperature). The glass reactor was sealed, and a magnetic stirrer was turned on. The reaction was carried out at 140 °C for 48 h to obtain the initial product (pale yellow transparent viscous liquid). The reaction was then terminated by cooling the glass reactor with an ice-water bath. The initial product was diluted with chloroform, and then ether was added to precipitate it. The solid was collected and dried in a vacuum oven at 50 °C for 12 h to obtain the purified product.

[0217] According to the test (test method is the same as in Example 1), the conversion rate of EtOx in this example is 46%; 1 Analysis of the H NMR spectrum and MALDI-TOF MS plot fully demonstrates that the product structure is well-defined and the functionalization degree of the end groups is 100%. The number-average molecular weight measured by SEC is 5.2 kg / mol (the theoretical number-average molecular weight calculated based on the feed ratio and conversion rate is 2.3 kg / mol), and the molecular weight distribution is 1.29.

[0218] In summary, the structural formula of the end-functionalized polyoxazoline synthesized in this embodiment is as follows:

[0219]

[0220] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing end-functionalized polyoxazoline, characterized in that, Includes the following steps: A cationic ring-opening polymerization reaction was carried out by mixing a weak Brønsted acid initiator, an ion exchange catalyst, and an oxazoline monomer to obtain end-functionalized polyoxazoline.

2. The method for preparing end-functionalized polyoxazoline according to claim 1, characterized in that: The molar ratio of the weak Brønsted acid initiator, ion exchange catalyst, and oxazoline monomer is 1:0.01-10:10-1000.

3. The method for preparing end-functionalized polyoxazoline according to claim 1 or 2, characterized in that: The weak Brønsted acid initiator is at least one of the following: aromatic carboxylic acid weak Brønsted acid initiators, aliphatic carboxylic acid weak Brønsted acid initiators, thiocarboxylic acid weak Brønsted acid initiators, organophosphate weak Brønsted acid initiators, and amino acid weak Brønsted acid initiators.

4. The method for preparing end-functionalized polyoxazoline according to claim 3, characterized in that: The aromatic carboxylic acid weak Brønsted acid initiator is at least one of benzoic acid, benzoic acid with a substituent group on the benzene ring, polycarboxylic aromatic acid, fused-ring carboxylic acid, polyphenyl carboxylic acid, and heterocyclic carboxylic acid; the substituent group in the benzoic acid with a substituent group on the benzene ring is at least one of C1-C6 alkyl, cyano, acetyl, azophenyl, dimethylamino, methylthio, hydroxyl, halogen, formyl, vinyl, ethynyl, borate ester, benzyloxycarbonyl-protected amino, tert-butyloxycarbonyl-protected amino, hydroxymethyl, and hydroxyethyl; the aliphatic carboxylic acid weak Brønsted acid initiator is C1-C6 20 The aliphatic carboxylic acid; the thiocarboxylic acid weak Brønsted acid initiator is at least one of thiofatty acid and thiobenzoic acid; the organophosphate weak Brønsted acid initiator is at least one of R-PO(OH)2 and R1R2PO(OH), wherein R, R1, and R2 are independently C1 to C2. 18 The amino acid initiator is one of the following: alkyl, phenyl, C1-C6 alkyl-substituted phenyl, methoxy-substituted phenyl, methylthio-substituted phenyl, halogen-substituted phenyl, heterocyclic group; the amino acid weak Brønsted acid initiator is at least one of the following: amino acid with amino group protected by Cbz group, amino acid with amino group protected by Boc group, amino acid with amino group protected by Fmoc group.

5. The method for preparing end-functionalized polyoxazoline according to claim 1 or 2, characterized in that: The ion exchange catalyst is at least one of the following: sulfonylimide salt catalyst, organic ionic liquid catalyst, borate catalyst, sulfonate catalyst, phosphate catalyst, halide salt catalyst, and sulfate catalyst.

6. The method for preparing end-functionalized polyoxazoline according to claim 5, characterized in that: The general chemical formula of the sulfonylimide salt catalyst is [M x+ [(RfSO2)2N] y- In the formula, M x+ For Li + Na + K + Ag + Zn 2+ Mg 2+ Ca 2+ One of them, Rf is one of halogen and perfluoroalkyl, y is 1 or 2; the general chemical formula of the organic ionic liquid catalyst is [Cat + ][An - In the formula, Cat + It is one of imidazolium and pyrrolidineonium, An - BF4 - PF6 - (CF3SO2)2N - One of the following: the borate catalyst has the general chemical formula of [M][BF4], [M][B(C6F5)4], or [M][B(C2O4)2], where M is one of an alkali metal cation, an alkaline earth metal cation, a transition metal cation, or an organic cation; the sulfonate catalyst has the general chemical formula of [M][RSO3], where M is one of an alkali metal cation, an alkaline earth metal cation, a transition metal cation, or an organic cation, and R is one of an alkyl or aryl group; the phosphate catalyst has the general chemical formula of [M]. x [PO4] y In the formula, M is one of alkali metal cations, alkaline earth metal cations, transition metal cations, and organic cations, x is an integer from 1 to 3, and y is an integer from 1 to 3; the general chemical formula of the halide salt catalyst is [M]X n In the formula, M is one of alkali metal cations, alkaline earth metal cations, transition metal cations, and organic cations, X is a halogen, and n is an integer from 1 to 3; the cation in the sulfate catalyst is one of alkali metal cations, alkaline earth metal cations, transition metal cations, and organic cations.

7. The method for preparing end-functionalized polyoxazoline according to claim 1 or 2, characterized in that: The oxazoline monomer is 2-oxazoline, containing C1 to C2 at the 2-position. 13 At least one of the following: 2-oxazoline, 2-isopropyl-2-oxazoline, 2-isobutyl-2-oxazoline, 2-tert-butyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-cyclohexyl-2-oxazoline, 2-phenyl-2-oxazoline, 2-(4-methylphenyl)-2-oxazoline, 2-(4-methoxyphenyl)-2-oxazoline, 2-(4-chlorophenyl)-2-oxazoline, 2-(4-nitrophenyl)-2-oxazoline, 2-methoxymethyl-2-oxazoline, 2-trichloromethyl-2-oxazoline, and 2,2'-bis(2-oxazoline).

8. The method for preparing end-functionalized polyoxazoline according to claim 1 or 2, characterized in that: The cationic ring-opening polymerization reaction was carried out at a temperature of 0℃ to 200℃ for a reaction time of 0.5h to 300h.

9. The method for preparing end-functionalized polyoxazoline according to claim 1 or 2, characterized in that: The weak Brønsted acid initiator, ion exchange catalyst, and oxazoline monomer are dispersed in a solvent to carry out a cationic ring-opening polymerization reaction.

10. The method for preparing end-functionalized polyoxazoline according to claim 9, characterized in that: The solvent is at least one selected from γ-butyrolactone, γ-butyrolactone with an alkyl substituent at the γ-position (C1-C8), dichloromethane, chloroform, toluene, tetrahydrofuran, 2-methyltetrahydrofuran, chlorobenzene, acetonitrile, sulfolane, ethyl acetate, propylene carbonate, ethyl 3-phenylpropionate, n-butyl acetate, dimethyl sulfoxide, N,N-dimethylformamide, and N,N-dimethylacetamide.

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