Multi-initiation site lewis base and preparation method and application thereof

Abstract

The application belongs to the technical field of polymer synthesis, and particularly relates to a multi-initiation site Lewis base and a preparation method and application thereof. The application relates to a tetrahydropyrimidine ene type multi-initiation site (1, 2, 3, 4 and 6) Lewis base which is cheap and easy to obtain, and is simple, efficient and easy to synthesize. The Lewis base is used to construct a corresponding Lewis acid-base pair catalyst by combining with a large steric hindrance organic aluminum Lewis acid, so that the active controllable polymerization of an acrylic ester monomer can be realized, and the preparation of a star-shaped acrylic ester-based thermoplastic elastomer polymer is achieved. In addition, a one-pot one-step method can be used to directly synthesize a star-shaped block copolymer with a strict block structure, and the method has the advantages of mild conditions, simple operation and rapid reaction. The synthesized star-shaped acrylic ester-based polymer has excellent mechanical properties as a thermoplastic elastomer.

Description

Technical Field

[0001] This invention belongs to the field of polymer synthesis technology, specifically relating to a Lewis base with multiple initiation sites, its preparation method, and its application. Background Technology

[0002] Star polymers are a class of polymeric materials with unique branched structures, consisting of at least three linear chains (arms) connected to a central functional group. Compared with traditional linear polymers, star polymers have significant structural advantages: First, their compact three-dimensional structure results in higher chain segment density, exhibiting lower viscosity in solutions and melts, significantly optimizing processing flowability; second, the synergistic effect of the central core and the various arms leads to a more uniform stress distribution, endowing the material with superior mechanical strength, impact resistance, and thermal stability; third, their unique topology makes them irreplaceable in applications such as interfacial stability, drug delivery, and nanoelectronics. These properties have made star polymers a research hotspot in the field of polymer materials, especially in the development of high-performance materials such as thermoplastic elastomers (TPEs).

[0003] Thermoplastic elastomers are a new type of polymer material that combines the elasticity of rubber with the processing properties of plastics. They have wide applications in automotive parts, medical devices, and consumer electronics, with a global annual production of 5 million tons. Among them, acrylate-based thermoplastic elastomers, with their excellent optical transparency, weather resistance, and low viscosity, are gradually becoming an important alternative to the widely used styrene-based thermoplastic elastomers. Early star-shaped acrylate-based thermoplastic elastomers were mainly prepared by living radical polymerization. For example, the arm composition of the Krzysztof Matyjaszewsk group is a block copolymer of polybutyl acrylate and polymethyl methacrylate (P... n BA- b -PMMA) Macromolecules ,2010, 43 (1227-1235) and polybutyl acrylate and poly α- Methylene -γ -Butyrolactone block copolymer (P n BA- b -PMBL)( Polymer ,2010, 51 The star-shaped acrylate-based thermoplastic elastomers (4806-4813) have elongation at break of 375-545% and 140-250%, respectively, and tensile strengths of 4.8-7.4 MPa and 3.1-7.8 MPa, respectively. In addition, Tang Chuanbing's research group synthesized lignin-grafted P... n BA- b-PMMA star-shaped acrylate-based thermoplastic elastomers have an elongation at break of 307~545% and a tensile strength of 4.8~14.95 MPa. Macromol. Rapid Commun ,2015, 36 (398-404). However, such polymerization methods require cumbersome multi-step sequential feeding processes, which are not conducive to large-scale commercial applications; and it is difficult to maintain high fidelity at the chain ends during long-term polymerization, resulting in a wide molecular weight distribution of the polymer and material properties that are not as expected. Recently, Professor Zhang Yuetao's research group developed a novel multi-initiation site imidazolium-based nitrogen heterocyclic olefin (NHOs) linked by tetraphenylethylene as a Lewis base to construct a corresponding Lewis acid-base pair catalyst, and utilized the unique zero-order kinetic mechanism of Lewis acid-base pair polymerization to synthesize a higher-performance (AB)4 star-shaped acrylate-based thermoplastic elastomer poly(2-methoxyethyl acrylate)-polymethyl methacrylate block copolymer (PMEA- b -PMMA) and poly2-methoxyethyl acrylate-polymethyl methacrylate-poly α- Methylene -γ -Butyrolactone block copolymer triblock copolymer (PMEA- b -PMMA- b -MMBL), whose elongation at break is 216~1863% and tensile strength is 3.5~19.1 MPa ( Angew. Chem. Int. Ed. 2024 63 (e202401265). However, due to the complicated synthesis steps and high raw material prices of this multi-initiation site Lewis base, large-scale preparation is difficult and not conducive to further commercial application. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a multi-initiation site Lewis base, its preparation method, and its applications. This invention utilizes a tetrahydropyrimidinene-type Lewis base with multiple initiation sites (1, 2, 3, 4, and 6 sites) that is inexpensive, readily available, and easily and efficiently synthesized, to construct Lewis acid-base pair catalysts. This provides a new route for preparing high-performance star-shaped polyacrylate-based thermoplastic elastomers under mild conditions. Using Lewis acid-base pairs constructed from Lewis bases and Lewis acids as catalysts, this invention enables rapid and controllable polymerization of acrylate monomers under mild conditions, and the resulting star-shaped acrylate-based polymers exhibit excellent mechanical properties as thermoplastic elastomers.

[0005] The technical solution of the present invention is as follows: A Lewis base with multiple initiation sites has the following structural formula: The preparation method of the multi-initiation site Lewis base is as follows: Benzyl bromide compounds with different numbers of reaction sites were refluxed with 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) in acetonitrile for 12-24 hours to obtain the corresponding quaternary ammonium salt intermediates. Subsequently, the quaternary ammonium salt intermediates were placed in tetrahydrofuran solvent at room temperature and deprotonated for 48-72 hours under the action of an excess of external strong base to obtain the corresponding Lewis bases NHOs. The molar ratio of benzyl bromide compounds to 1,5-diazabicyclo[4.3.0]non-5-ene was 1:1, and the molar ratio of external strong base to benzyl bromide compounds was 2:1-3:1.

[0006] The above reaction is shown in the following equation: The benzyl bromide compound is one or a mixture of two or more of the following: benzyl bromide, 1,4-di(bromomethyl)benzene, 1,3,5-tri(bromomethyl)benzene, 1,2,4,5-tetra(bromomethyl)benzene, and hexa(bromomethyl)benzene.

[0007] The added alkali is sodium hydride (NaH) or potassium tert-butoxide (NaH). t One or more of the following (BuOK) combinations.

[0008] The multi-initiation site Lewis base is applied to the preparation of star-shaped acrylate-based thermoplastic elastomer polymers. The specific process involves constructing a corresponding Lewis acid-base pair catalyst using the multi-initiation site Lewis base and an organoaluminum Lewis acid, achieving rapid polymerization of acrylate monomers in a solvent to obtain star-shaped acrylate-based thermoplastic elastomer polymers with rich topological structures. This polymerization reaction features high polymerization reactivity, controllable polymerization rate, controllable polymer molecular weight and molecular weight distribution, complete monomer conversion, and good substrate applicability. The steps include: adding acrylate monomers to an organic solvent at room temperature, followed by the sequential addition of an organoaluminum Lewis acid and a Lewis base to carry out the polymerization reaction; wherein the molar ratio of acrylate monomers to the multi-initiation site Lewis base is 400:1 to 3200:1, and the molar ratio of the multi-initiation site Lewis base to the organoaluminum Lewis acid is 1:2 to 1:12.

[0009] The organoaluminum Lewis acid is i Bu2Al(BHT) or MeAl(BHT)2, the structural expression is as follows: The acrylate monomer is one or a mixture of two or more of methyl methacrylate (MMA), isobornyl methacrylate (IBOMA), and 2-methoxyethyl 2-acrylate (MEA), with the following structural expression: Preferably, the organic solvent is toluene; the polymerization reaction temperature is 25°C.

[0010] Preferably, after the polymerization reaction, the process further includes: adding n-hexane as a quenching agent to the obtained polymerization reaction solution, followed by washing and drying.

[0011] The beneficial effects of this invention are: The multi-initiation-site Lewis base provided by this invention is inexpensive and readily available, with a simple and efficient synthesis procedure. It can prepare Lewis bases with 1, 2, 3, 4, and 6 initiation sites, solving the problems of cumbersome synthesis and expensive raw materials in existing multi-initiation-site Lewis bases, and facilitating large-scale preparation. The acid-base pair catalyst constructed with organoaluminum Lewis acids can achieve rapid and controlled polymerization of acrylate monomers under mild conditions, with advantages such as high monomer conversion and good substrate compatibility. The resulting star-shaped polyacrylate-based thermoplastic elastomer exhibits excellent mechanical properties, providing a new route for the commercial production of high-performance materials of this type, with broad application prospects. Attached Figure Description

[0012] Figure 1 This is the 1H NMR spectrum of NHO1; Figure 2 This is the carbon NMR spectrum of NHO1; Figure 3 This is the hydrogen NMR spectrum of NHO2; Figure 4 This is the carbon NMR spectrum of NHO2; Figure 5 This is the hydrogen NMR spectrum of NHO3; Figure 6 This is the carbon NMR spectrum of NHO3; Figure 7 This is the 1H NMR spectrum of NHO4; Figure 8 This is the carbon NMR spectrum of NHO4; Figure 9 This is a single crystal analytical image of NHO4 (CCDC: 2535148). Figure 10 This is the 1H NMR spectrum of NHO5; Figure 11 This is the carbon NMR spectrum of NHO5; Figure 12 This is a single crystal analysis image of NHO5 (CCDC: 2535149); Figure 13 It is PMEA- b -DOSY spectrum of PMMA block copolymer; Figure 14 It is PMEA- b DOSY spectrum of PIBOMA block copolymer; Figure 15 It is PMEA- b -PMMA and PMEA- b DSC curves of PIBOMA block copolymers and PMMA, PIBOMA and PMEA homopolymers; Figure 16 The PMEA- obtained under the same monomer ratio but different arm numbers b -PMMA and PMEA- b - Stress-strain curves of PIBOMA; Figure 17 The PMEA- obtained under the same number of arms but different monomer ratios b -PMMA and PMEA- b - Stress-strain curves of PIBOMA; Figure 18 Under the same monomer ratio but different arm numbers, PMEA- b - Cyclic stretching diagram of PMMA; Figure 19 Under the same monomer ratio but different arm numbers, PMEA- b - PIBOMA's cyclic stretching diagram; Figure 20 This is a schematic diagram of the structure of the multi-initiation site Lewis base of the present invention. Detailed Implementation

[0013] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0014] Example 1 Synthesis of NHO1 In a 250 mL round-bottom flask, benzyl bromide (20.0 mmol), DBN (40.0 mmol), and 80 mL of ultra-dry acetonitrile were added, and the solution was heated to reflux for 12 hours. After cooling to room temperature, the volatile solvent was removed under vacuum. The resulting solid was washed with tetrahydrofuran and dried under vacuum overnight to obtain a cream-colored solid NHO1·HBr in 95% yield. Subsequently, NaH (6.0 mmol) and NHO1·HBr (2.0 mmol) were added to 20 mL of ultra-dry tetrahydrofuran. The mixture was placed in the dark and stirred at room temperature for 48 hours. After the reaction was complete, the insoluble salt was removed by filtration. The filtrate was then desolventized under vacuum to obtain a yellow oily NHO1 in 92% yield. The 1H and 1C NMR spectra of the obtained NHO1 are shown below. Figure 1 and Figure 2 As shown. 1 H NMR (400 MHz, C6D6) δ 7.25 (d, J = 7.1 Hz, 2H), 7.14 (t, J = 7.7 Hz, 2H), 7.06 (t, J = 7.3 Hz, 1H), 3.95 (s, 2H), 3.87 (s,1H), 2.93 (t, J = 8.0 Hz, 2H), 2.49–2.39 (m, 6H), 1.62–1.56 (m, 2H). 13 C{ 1 H NMR (101 MHz, C6D6) δ 154.6, 139.0, 128.6, 128.4, 127.2, 74.9, 56.3, 55.0, 50.5,47.5, 26.9, 24.1 (s).HRMS(ESI): [C 14 H 19 N2] + [M+H] + calcd.215.1543, found215.1545 m / z . Example 2 Synthesis of NHO2 In a 250 mL round-bottom flask, 20.0 mmol of 1,4-di(bromomethyl)benzene, 40.0 mmol of DBN, and 120 mL of ultra-dry acetonitrile were added, and the solution was heated to reflux for 12 hours. After cooling to room temperature, the solvent was removed by filtration, the solid was washed with tetrahydrofuran, and dried under vacuum overnight to obtain a white solid NHO2·2HBr in 89% yield. Subsequently, NaH ( t BuOK (2.0 mmol) and NHO2·2HBr (2.0 mmol) were added to 20 mL of ultra-dry tetrahydrofuran. The mixture was placed in the dark and stirred at room temperature for 48 hours. After the reaction was complete, the insoluble salt was removed by filtration. Subsequently, the solvent was removed from the filtrate under vacuum to obtain a pale yellow solid NHO2, with a yield of 84%. The 1H NMR spectrum and 1C NMR spectrum of the obtained NHO2 are shown below. Figure 3 and Figure 4 As shown. H NMR (400 MHz, C6D6) δ 7.24 (s,4H), 3.96 (s, 4H), 3.89 (t, J = 2.2 Hz, 2H), 2.93 (t, J = 8.1 Hz, 4H), 2.50–2.46(m, 8H), 2.44–2.39 (m, 4H), 1.63–1.57 (m, 4H). 13 C{ 1 H NMR (101 MHz, C6D6) δ 154.6,137.7, 128.5, 74.8, 56.1, 55.0, 50.5, 47.5, 26.9, 24.1 (s).HRMS(ESI):[C 22 H 32 N4] 2+ [M+2H] 2+ calcd. 176.1308, found 176.1306 m / z . Example 3 Synthesis of NHO3 In a 250 mL round-bottom flask, 1,3,5-tris(bromomethyl)benzene (10.0 mmol), DBN (30.0 mmol), and 80 mL of ultra-dry acetonitrile were added, and the solution was heated to reflux and reacted for 24 hours. After cooling to room temperature, the volatile solvent was removed under vacuum. The resulting solid was washed with tetrahydrofuran and dried under vacuum overnight to obtain a cream-colored solid, NHO3·3HBr, in 93% yield. Subsequently, NaH (18.0 mmol), t BuOK (0.3 mmol) and NHO3·3HBr (2.0 mmol) were added to 20 mL of ultra-dry tetrahydrofuran. The mixture was placed in the dark and stirred at room temperature for 48 hours. After the reaction was complete, the insoluble salt was removed by filtration. Subsequently, the solvent was removed from the filtrate under vacuum to obtain a pale yellow solid NHO3 in 86% yield. The 1H NMR and 1C NMR spectra of the obtained NHO3 are shown below. Figure 5 and Figure 6 As shown. 1 HNMR (400 MHz, C6D6) δ 7.26 (s, 3H), 3.98 (s, 6H), 3.88 (s, 3H), 2.94 (t, J = 8.0Hz, 6H), 2.52 (q, J = 6.2 Hz, 12H), 2.43 (t, J = 8.1 Hz, 6H), 1.68–1.63 (m, 6H). 13 C{ 1 H NMR (101 MHz, C6D6) δ 154.6, 139.3, 126.8, 74.9, 56.3, 55.0, 50.5, 47.6,27.0, 24.1 (s).HRMS(ESI): [C 30 H 45 N6] 3+ [M+3H] 3+ calcd. 163.1230, found 163.1222 m / z . Example 4 Synthesis of NHO4 In a 250 mL round-bottom flask, 1,2,4,5-tetra(bromomethyl)benzene (10.0 mmol), DBN (40.0 mmol), and 120 mL of ultra-dry acetonitrile were added, and the solution was heated to reflux for 24 hours. After cooling to room temperature, the solvent was removed by filtration, the solid was washed with tetrahydrofuran, and dried under vacuum overnight to obtain a white solid NHO4·4HBr in 95% yield. Subsequently, NaH (12.0 mmol), t BuOK (0.2 mmol) and NHO4·4HBr (1.0 mmol) were added to 20 mL of ultra-dry tetrahydrofuran. The mixture was placed in the dark and stirred at room temperature for 72 hours. After the reaction was complete, the insoluble salt was removed by filtration. Subsequently, the solvent was removed from the filtrate under vacuum to obtain a pale yellow solid NHO4, with a yield of 84%. The 1H NMR and 1C NMR spectra of the obtained NHO4 are shown below. Figure 7 and Figure 8 As shown, the corresponding single-crystal analytical image is as follows: Figure 9 As shown. 1 H NMR (400 MHz, C6D6) δ 7.48 (s, 2H), 4.16 (s, 8H), 3.91 (s, 4H), 2.94 (t, J = 8.0 Hz, 4H), 2.57–2.50 (m, 16H), 2.42 (t, J = 8.0 Hz, 8H), 1.69–1.63(m, 8H). 13 C{ 1 H NMR (101 MHz, C6D6) δ 154.5, 135.4, 130.9, 75.1, 55.0, 53.7, 50.6,47.6, 27.0, 24.2 (s).HRMS(APCI): [C 38 H 55 N8] + [M+H] + calcd. 623.4544, found623.4547 m / z . Example 5 Synthesis of NHO5 In a 250 mL round-bottom flask, hexa(bromomethyl)benzene (5.0 mmol), DBN (30.0 mmol), and 100 mL of ultra-dry acetonitrile were added, and the solution was heated to reflux and reacted for 24 hours. After cooling to room temperature, the solvent was removed by filtration, the solid was washed with tetrahydrofuran, and dried under vacuum overnight to obtain a white solid NHO5·6HBr in 86% yield. Subsequently, NaH (18.0 mmol), t BuOK (0.3 mmol) and NHO5·6HBr (1.0 mmol) were added to 30 mL of ultra-dry tetrahydrofuran. The mixture was placed in the dark and stirred at room temperature for 72 hours. After the reaction was complete, the insoluble salt was removed by filtration. Subsequently, the solvent was removed from the filtrate under vacuum to obtain a pale yellow solid NHO5 in 90% yield. The 1H NMR and 1C NMR spectra of the obtained NHO5 are shown below. Figure 10 and Figure 11 As shown, the corresponding single-crystal analytical image is as follows: Figure 12 As shown. 1 H NMR (400 MHz, C6D6) δ 4.52 (s, 12H), 4.01 (s, 6H), 2.90 (t, J = 8.0Hz, 12H), 2.57 (t, J = 5.5 Hz, 12H), 2.47 (t, J = 5.5 Hz, 12H), 2.40 (t, J = 8.1Hz, 12H), 1.62 (p, J = 5.3 Hz, 12H), 1.65–1.59 (m, 12H). 13 C{ 1 H NMR (101 MHz, C6D6) δ 154.3, 138.2, 75.6, 54.9, 50.8, 49.6, 46.2, 27.0, 24.3 (s).HRMS(APCI):[C 54 H 79 N 12 ] + [M+H] + calcd. 895.6545, found 895.6548 m / z . Example 6 Homopolymerization of acrylate monomers The polymerization reaction is carried out in an argon-filled glove box. Taking the homopolymerization of methyl methacrylate (MMA) as an example, in a 20 mL glass bottle, MMA is first reacted with Lewis acid (such as...) i Bu2Al(BHT)) and a portion of toluene were premixed, with the amount of Lewis acid added referred to Table 1. Subsequently, a toluene solution of a Lewis base (such as NHO1) was added under vigorous stirring to initiate the polymerization reaction; the amount of Lewis base added is also referred to Table 1. After the desired polymerization time was reached, 0.1 mL of the reaction solution was rapidly added to 0.5 mL of deuterated chloroform (CDCl3) stabilized by 2,6-di-tert-butyl-p-cresol (BHT) to quench the reaction. The reaction solution was then analyzed by 1H NMR spectroscopy, and the corresponding monomer conversion rate was calculated. After the reaction time was reached, the reaction flask was removed from the glove box, and the reaction solution was poured into a beaker containing 200 mL of n-hexane to precipitate the polymer. After thorough stirring, the n-hexane was discarded, and the mixture was washed three times. The polymer was then dried overnight in a vacuum oven at 50°C until constant weight. The polymerization results are shown in Table 1.

[0015] Table 1: Homopolymerization results of acrylate monomers [a]

[0016] [a] The polymerization reaction was carried out in a toluene solution at room temperature, with an initial monomer concentration of 1.0 mol / L. [b] The monomer conversion rate was measured using 1H NMR spectroscopy. [c] Number average molecular weight ( M n ) and dispersion Đ = M w / M n ) by gel permeation chromatography (GPC) at 40 o C below N,N Dimethylformamide (DMF) was used as the mobile phase, calculated using PMMA as the standard.

[0017] Example 7: One-step synthesis of linear and star-shaped acrylate block copolymers The polymerization reaction was carried out in an argon-filled glove box. The copolymer was poly(2-methoxyethyl acrylate)-polymethyl methacrylate block copolymer (PMEA- b Taking the synthesis of MEA and MMA as an example, in a 20 mL glass bottle, MEA, MMA, and Lewis acid (-PMMA) are first mixed. iBu2Al(BHT)) and a portion of toluene were premixed. Subsequently, a toluene solution of Lewis base (NHO2) was added under vigorous stirring to initiate the polymerization reaction. The amount of Lewis base added is referenced in Table 2.

[0018] Table 2: Synthesis and mechanical properties of acrylate-based block copolymers [a]

[0019] [a] Polymerization was carried out in a toluene solution at room temperature, with an initial monomer concentration of 1.0 mol / L. The Lewis base was: NHOs, and the Lewis acid was: i Bu2Al(BHT). [b] Number average molecular weight ( M n ) and dispersion Đ = M w / M n ) by gel permeation chromatography (GPC) at 30 o Calculations were performed using tetrahydrofuran (THF) as the mobile phase at C, with PMMA as the standard. [c] The elongation at break, tensile strength, and tensile modulus were determined by stress-strain tensile testing.

[0020] After the desired polymerization time was reached, 0.1 mL of the reaction solution was rapidly added to 0.5 mL of CDCl3 stabilized by 2,6-di-tert-butyl-p-cresol (BHT) to quench the reaction. The reaction solution was then analyzed by 1H NMR spectroscopy, and the corresponding monomer conversion rate was calculated. After the reaction time was reached, the reaction flask was removed from the glove box, and the reaction solution was poured into a beaker containing 200 mL of n-hexane to precipitate the polymer. After thorough stirring, the n-hexane was discarded, and the mixture was washed three times. The polymer was then dried overnight in a vacuum oven at 50 °C until a constant weight was achieved. The polymerization results are shown in Table 2.

[0021] Figure 13 and Figure 14 They are PMEA- b -PMMA and PMEA- b The DOSY spectrum of the PIBOMA block copolymer shows that there is only one diffusion coefficient, indicating that the obtained copolymer has a strict block structure.

[0022] Figure 15 It is PMEA- b -PMMA and PMEA- bThe DSC curves of the PIBOMA block copolymer and the homopolymers of PMMA, PIBOMA and PMEA show that both block copolymers have two glass transition temperatures, corresponding to PMEA, PMMA and PIBOMA respectively, indicating that the block copolymers have obvious phase separation.

[0023] Figure 16 The PMEA- obtained under the same monomer ratio but different arm numbers b -PMMA and PMEA- b The stress-strain curve of PIBOMA shows that star-shaped block copolymers, as thermoplastic elastomers, have superior mechanical properties.

[0024] Figure 17 The PMEA- obtained under the same number of arms but different monomer ratios b -PMMA and PMEA- b The stress-strain curve of PIBOMA shows that the properties of thermoplastic elastomers can be adjusted by changing the ratio of hard segments PMMA and PIBOMA, with elongation at break between 519% and 1856% and tensile strength between 4.5 and 12.5 MPa.

[0025] Figure 18 Under the same monomer ratio but different arm numbers, PMEA- b - A cyclic stretching graph of PMMA, from which you can see that PMEA- b -The elastic recovery rate of PMMA elastomers decreases with the increase of the number of arms.

[0026] Figure 19 Under the same monomer ratio but different arm numbers, PMEA- b -PIBOMA's cyclic stretching graph shows that PMEA- b -PIBOMA type elastomers have a significantly better elastic recovery rate than PMEA- b -PMMA type elastomer.

[0027] Figure 20 This is a schematic diagram of the structure of the multi-initiation site Lewis base of the present invention.

Claims

1. A Lewis base with multiple initiation sites, characterized in that, The structural expression of the multi-initiation site Lewis base is as follows: 。 2. The method for preparing a multi-initiation site Lewis base according to claim 1, characterized in that, The steps are as follows: Benzyl bromide compounds with different numbers of reaction sites were refluxed with 1,5-diazabicyclo[4.3.0]non-5-ene in acetonitrile for 12-24 hours to obtain the corresponding quaternary ammonium salt intermediates. Subsequently, the quaternary ammonium salt intermediates were placed in tetrahydrofuran solvent at room temperature and deprotonated for 48-72 hours under the action of an excess of external strong base to obtain the corresponding Lewis base NHOs.

3. The method for preparing a multi-initiation site Lewis base according to claim 2, characterized in that, The molar ratio of benzyl bromide to 1,5-diazabicyclo[4.3.0]non-5-ene is 1:1, and the molar ratio of the external strong base to benzyl bromide is 2:1 to 3:

1.

4. The method for preparing a multi-initiation site Lewis base according to claim 2, characterized in that, The benzyl bromide compound is one or a mixture of two or more selected from benzyl bromide, 1,4-di(bromomethyl)benzene, 1,3,5-tri(bromomethyl)benzene, 1,2,4,5-tetra(bromomethyl)benzene, and hexa(bromomethyl)benzene; the external strengthening base is sodium hydride (NaH) or potassium tert-butoxide (NaH). t One or more of the following (BuOK) combinations.

5. The multi-initiation site Lewis base of claim 1 is applied to the preparation of star-shaped acrylate-based thermoplastic elastomer polymers.

6. The application according to claim 5, characterized in that, The preparation method includes the following steps: adding acrylate monomers to an organic solvent at room temperature, and then sequentially adding organoaluminum Lewis acid and Lewis base to carry out a polymerization reaction.

7. The application according to claim 5, characterized in that, The molar ratio of acrylate monomers to multi-initiation site Lewis bases is 400:1 to 3200:1, and the molar ratio of multi-initiation site Lewis bases to organoaluminum Lewis acids is 1:2 to 1:

12.

8. The application according to claim 5, characterized in that, The organoaluminum Lewis acid is i Bu2Al(BHT) or MeAl(BHT)2; the acrylate monomer is one or a mixture of two or more of methyl methacrylate, isobornyl methacrylate, and 2-methoxyethyl 2-acrylate.

9. The application according to claim 5, characterized in that, The organic solvent is toluene; the polymerization reaction temperature is 25°C.

10. The application according to claim 5, characterized in that, After the polymerization reaction, the process further includes: adding n-hexane as a quenching agent to the obtained polymerization reaction solution, followed by washing and drying.

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