A high-performance bio-based closed-loop recyclable thermoplastic elastomer and its preparation method

Abstract

The present invention provides a high-performance bio-based closed-loop recyclable thermoplastic elastomer (TPE) and a method for preparing the same. The prepared thermoplastic elastomer can be depolymerized and recovered to obtain monomers, which can then be polymerized again, achieving a closed cycle of "monomer-polymer-monomer". The method provided by the present invention has the following advantages: 1) the raw materials used are inexpensive and biomass-derived, and the prepared block copolymer can be completely depolymerized and recovered to obtain monomers in the presence of a catalyst. The monomers can then be polymerized again, and the resulting TPE has the same mechanical properties as the initial one; 2) the catalyst system used has high catalytic activity and high monomer conversion rate; 3) the prepared TPE material has high mechanical strength, good resilience, and a high operating temperature.

Description

Technical Field

[0001] The present invention relates to the fields of polymer materials and chemistry and chemical engineering. Specifically, the present invention relates to a high-performance, low-cost, bio-based closed-loop recyclable thermoplastic elastomer and a preparation method thereof. Background Art

[0002] Thermoplastic elastomers (TPEs) are an important class of polymer materials that have the reusable processing properties of thermoplastics and the flexibility and high elasticity of traditional rubber materials. They are widely used in pressure-sensitive adhesives, automotive parts, medical devices and other fields. ABA-type triblock copolymers are an important component of thermoplastic elastomers, in which block A is a hard segment, usually composed of a high glass transition temperature (T g ) or amorphous polymers with a higher melting point (T m ) is composed of a crystalline polymer, block B is a rubbery soft segment, and has a lower T g or T m Polymers. Soft and hard blocks are usually thermodynamically incompatible. When the copolymer has a suitable composition and molecular weight, microphase separation occurs between the soft and hard segments, and the hard segments serve as physical crosslinking points distributed in the rubbery matrix formed by the soft segments, thereby giving the material strength and resilience. In addition to ABA-type triblock copolymers, copolymers with other topological structures can also be used as thermoplastic elastomer materials if they have a suitable composition and molecular weight, such as multi-block copolymers, star-shaped block copolymers, grafted copolymers, bottle-brush copolymers, and hyperbranched copolymers. Among them, multi-arm star-shaped block copolymers can disperse stress more evenly during stretching due to the presence of star cores, and exhibit higher tensile strength and better elastic recovery compared to ABA-type triblock copolymers.

[0003] In 1965, Shell Chemical Company developed polystyrene-based thermoplastic elastomers, which offer excellent performance, low cost, and widespread applications. However, these thermoplastic elastomers are derived from non-renewable petroleum resources, and their backbones have a stable carbon-carbon structure, making them non-degradable in the natural environment. Their large-scale production and improper disposal after use can lead to serious resource and environmental pollution problems. The best solution to addressing environmental pollution and resource waste may be the development of chemically recyclable polymers with closed-loop cycles that can be depolymerized into their original monomers or converted into value-added chemicals. The use of safe and inexpensive bio-based cyclic lactone monomers to prepare recyclable thermoplastic elastomers is gaining increasing attention. β-Methyl-δ-valerolactone (βMδVL), a β-substituted δ-valerolactone, can be produced from glucose fermentation at a cost of only 15,000 yuan per ton. Paradioxanone (PDO), a commercially available monomer, can also be synthesized from bio-sourced diethylene glycol at a cost of 50,000 yuan per ton. By selecting an appropriate catalytic system and achieving sequential ring-opening polymerization of β-methyl-δ-valerolactone and p-dioxanone, a well-defined triblock copolymer of poly(p-dioxanone)-b-poly(β-methyl-δ-valerolactone)-b-poly(p-dioxanone) (PPDO-b-PβMδVL-b-PPDO) can be prepared. By adjusting the composition and molecular weight of the triblock copolymer, thermoplastic elastomers with excellent mechanical properties and high resilience are expected to be obtained.

[0004] Previous literature reported that δ-valerolactone (δVL) and α-alkyl-substituted valerolactone were used as raw materials to prepare a completely closed-loop recyclable triblock thermoplastic elastomer, which showed excellent mechanical properties and high resilience. However, since the melting point of poly(δ-valerolactone) is only 60°C, the maximum operating temperature of the thermoplastic elastomer is low and it cannot adapt to high-temperature usage scenarios (Nat. Commun., 2024, 15, 7904). The current maximum operating temperature of closed-loop recyclable TPE materials is somewhat different from that of polystyrene elastomers and cannot meet application requirements. In addition, the fracture strength and elastic recovery rate of closed-loop recyclable TPE can be improved by multi-arm star block copolymers.

[0005] In view of this, the present invention provides a high-performance bio-based closed-loop recyclable thermoplastic elastomer and a preparation method thereof, namely, a method for achieving sequential ring-opening polymerization of β-methyl-δ-valerolactone and p-dioxanone to prepare a well-structured poly-p-dioxanone-b-poly(β-methyl-δ-valerolactone)-b-poly-p-dioxanone triblock copolymer or a star-shaped multi-arm block copolymer. The prepared block copolymer has the properties of a thermoplastic elastomer. The method provided by the present invention has the following advantages: 1) The raw materials used are inexpensive and derived from biomass, and the prepared block copolymer can be completely depolymerized and recovered to obtain cyclic lactone monomers in the presence of a catalyst. The monomers can be polymerized again, and the mechanical properties of the obtained TPE are the same as those of the initial one; 2) The catalytic system used has high catalytic activity and high monomer conversion rate, and the conversion rates of β-methyl-δ-valerolactone and p-dioxanone can reach more than 85%; 3) The prepared TPE material has high mechanical strength, good resilience, and high operating temperature. Summary of the Invention

[0006] The purpose of the present invention is to provide a high-performance bio-based closed-loop recyclable thermoplastic elastomer and a preparation method thereof.

[0007] The thermoplastic elastomer provided by the present invention has an ABA type triblock copolymer structure or (AB) x A star-shaped multi-arm block copolymer structure, wherein x≥2; the segment A has a structure as shown in formula (I), and the segment B has a structure as shown in formula (II).

[0008]

[0009] The feature is that m is a natural number greater than or equal to 200, n is a natural number greater than or equal to 100, and m≥n.

[0010] The present invention also provides the above-mentioned ABA type triblock copolymer or (AB) x The preparation method of the star-shaped multi-arm block copolymer comprises the following steps:

[0011] (1) Dissolve the initiator, organic base and urea in an organic solvent and stir at room temperature for 1 to 10 minutes;

[0012] (2) adding β-methyl-δ-valerolactone to the above mixed solution and reacting at -20 to 60°C for 0.1 to 10 hours;

[0013] (3) adding p-dioxanone to the above reaction system, continuing the reaction at -20 to 60°C for 0.1 to 10 hours, and then adding an acidic substance to terminate the reaction to obtain an ABA type triblock copolymer or (AB) x Star-shaped multi-arm block copolymer.

[0014] In the above preparation method, the urea may be one of the following structures:

[0015]

[0016]

[0017] The organic base has one of the following structures:

[0018]

[0019] In the above preparation method, the initiator is a polyol, specifically ethylene glycol, 1,2-propylene glycol, 1,2-butanediol, 1,4-butanediol, 1,4-cyclohexanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,2-benzenedimethanol, 1,3-benzenedimethanol, 1,4-benzenedimethanol, pentaerythritol, dipentaerythritol, trimethylolpropane; when a diol is used as an initiator, a poly(p-dioxanone)-b-poly(β-methyl-δ-valerolactone)-b-poly(p-dioxanone) triblock copolymer is prepared; when a polyol containing two or more hydroxyl groups is used as an initiator, (AB) x Star-shaped multi-arm block copolymers;

[0020] The molar ratio of the organic base to the initiator is 0.1 / 1 to 20 / 1; the molar ratio of the organic base to urea is 1 / 1 to 1 / 10.

[0021] In the above preparation method, the organic solvent in step (1) is toluene, tetrahydrofuran, dichloromethane, chloroform, acetonitrile, or N,N-dimethylformamide.

[0022] In the above preparation method, the molar concentration of the β-methyl-δ-valerolactone in the system in step (2) is 4 to 9.1 mol / L; the molar ratio of the β-methyl-δ-valerolactone to the initiator is 200 / 1 to 3000 / 1.

[0023] In the above preparation method, the molar concentration of the p-dioxanone in the system in step (3) is 0.1 to 12.4 mol / L; the molar ratio of the p-dioxanone to β-methyl-δ-valerolactone is 1 / 1 to 1 / 20.

[0024] In the above preparation method, the acidic substance can be acetic acid, benzoic acid, hydrochloric acid, sulfuric acid, or phosphoric acid, and the molar ratio of the acidic substance to the organic base is 1 / 1 to 10 / 1.

[0025] The present invention also provides a recycling method for the thermoplastic elastomer, comprising the following steps:

[0026] (1) mixing a thermoplastic elastomer with stannous octoate, heating at 100-200° C. for 2-10 hours, and distilling under reduced pressure to obtain a high-purity mixture of p-dioxanone and β-methyl-δ-valerolactone;

[0027] (2) The mixture is separated to obtain p-dioxanone and β-methyl-δ-valerolactone, which are then repolymerized to obtain an ABA type triblock copolymer or (AB) x Star-shaped multi-arm block copolymer. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The polydioxanone-b-poly (β-methyl-δ-valerolactone)-b-polydioxanone prepared in Example 1 1 H NMR spectrum.

[0029] Figure 2 The polydioxanone-b-poly (β-methyl-δ-valerolactone)-b-polydioxanone prepared in Example 1 13 C NMR spectrum.

[0030] Figure 3 1 is a DSC spectrum of polydioxanone-b-poly(β-methyl-δ-valerolactone)-b-polydioxanone prepared in Examples 1 to 3 at a scanning rate of 10° C. / min.

[0031] Figure 4 The polydioxanone-b-poly (β-methyl-δ-valerolactone)-b-polydioxanone and β-methyl-δ-valerolactone, p-dioxanone and the recycled β-methyl-δ-valerolactone, p-dioxanone prepared in Example 2 1 H NMR spectrum.

[0032] Figure 5 These are uniaxial stretching spectra of polydioxanone-b-poly(β-methyl-δ-valerolactone)-b-polydioxanone prepared in Example 2 and polydioxanone-b-poly(β-methyl-δ-valerolactone)-b-polydioxanone prepared by repolymerizing recycled monomers.

[0033] Figure 6 1 is the DSC spectrum of polydioxanone-b-poly(β-methyl-δ-valerolactone)-b-polydioxanone prepared in Examples 4 to 6 at a scanning rate of 10° C. / min.

[0034] Figure 7 1 is a uniaxial stretching spectrum of polydioxanone-b-poly(β-methyl-δ-valerolactone)-b-polydioxanone prepared in Examples 1 to 3.

[0035] Figure 8 1 is a uniaxial stretching spectrum of polydioxanone-b-poly(β-methyl-δ-valerolactone)-b-polydioxanone prepared in Examples 4 to 6.

[0036] Figure 9 This is the DMA spectrum of polydioxanone-b-poly(β-methyl-δ-valerolactone)-b-polydioxanone prepared in Example 6.

[0037] Figure 10 This is the stretching cycle spectrum of the three-arm star-shaped block copolymer (PβMδVL-PPDO)3 prepared in Example 7.

[0038] Figure 11 This is the DMA spectrum of the three-arm star-shaped block copolymer (PβMδVL-PPDO)3 prepared in Example 7. DETAILED DESCRIPTION

[0039] The present invention is described in detail with reference to the following embodiments, but the present invention is not limited to these embodiments.

[0040] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0041] Comparative Example 1

[0042] (0.08 mmol, 8.3 μL) benzyl alcohol, (0.08 mmol, 12.0 μL) 1,8-diazabicyclo-7-undecene, (0.16 mmol, 77.5 mg) 1,3-bis(3,5-bis(trifluoromethyl)phenyl)urea Dissolve in 3.2 mL of tetrahydrofuran and stir at room temperature for 10 minutes. Add (56 mmol, 6.1 mL) of β-methyl-δ-valerolactone to the reaction tube and react at 30°C under nitrogen for 4 hours. Then, dissolve (16 mmol, 1.6 g) of p-dioxanone in 1.3 mL of tetrahydrofuran and add the above system. React at 25°C under nitrogen for 30 minutes, and terminate the reaction by adding 1 mL of dilute hydrochloric acid. The reaction mixture is dissolved in 20 mL of chloroform and poured into 150 mL of methanol. Centrifuge and precipitate to obtain a polymer. Nuclear magnetic resonance characterization shows that the polymer is a diblock copolymer, namely poly(β-methyl-δ-valerolactone)-b-poly(p-dioxanone). Compared with Example 1, the elongation at break is low and there is a significant yield point, making it unsuitable for use as a thermoplastic elastomer.

[0043] Comparative Example 2

[0044] (0.08 mmol, 11.1 mg) 1,4-benzenedimethanol, (0.08 mmol, 12.0 μL) 1,8-diazabicyclo-7-undecene, (0.16 mmol, 77.5 mg) 1,3-bis(3,5-bis(trifluoromethyl)phenyl)urea The mixture was dissolved in 230 μL of tetrahydrofuran and stirred at room temperature for 10 minutes. β-methyl-δ-valerolactone (4 mmol, 436 μL) was then added to the reaction tube, and the reaction was carried out at 30°C under nitrogen for 4 hours. p-Dioxanone (8 mmol, 816 mg) was then dissolved in 689 μL of tetrahydrofuran and added to the above system. The reaction was carried out at 25°C under nitrogen for 30 minutes, and 1 mL of dilute hydrochloric acid was added to terminate the reaction. The reaction mixture was dissolved in 20 mL of chloroform and poured into 150 mL of methanol. The polymer was precipitated by centrifugation to obtain a polymer. Nuclear magnetic resonance imaging (NMR) analysis revealed that the polymer was a triblock copolymer, poly(p-dioxanone-b-poly(β-methyl-δ-valerolactone)-b-poly(p-dioxanone). Compared to Example 1, m = 50, n = 100, and the total degree of polymerization (DP) = 150. Since m and n are not within the specified ranges, it cannot be used as a thermoplastic elastomer.

[0045] Example 1

[0046] (0.08 mmol, 11.1 mg) 1,4-benzenedimethanol, (0.08 mmol, 12.0 μL) 1,8-diazabicyclo-7-undecene, (0.16 mmol, 77.5 mg) 1,3-bis(3,5-bis(trifluoromethyl)phenyl)urea Dissolve in 3.2 mL of tetrahydrofuran, stir at room temperature for 10 min, add (56 mmol, 6.1 mL) of β-methyl-δ-valerolactone to the reaction tube, and react at 30 ° C under nitrogen protection for 4 hours. Then dissolve (16 mmol, 1.6 g) of p-dioxanone in 1.3 mL of tetrahydrofuran and add the above system, react at 25 ° C under nitrogen protection for 30 minutes, and add 1 mL of dilute hydrochloric acid to terminate the reaction. The reaction mixture was dissolved in 20 mL of chloroform, poured into 150 mL of methanol, and centrifuged to precipitate to obtain a polymer. The polymer was characterized by nuclear magnetic resonance as a triblock copolymer, namely poly-p-dioxanone-b-poly(β-methyl-δ-valerolactone)-b-poly-p-dioxanone, and its nuclear magnetic hydrogen spectrum was as follows Figure 1 As shown, the NMR carbon spectrum is Figure 2 As shown, the DSC spectrum is Figure 3 As shown, the stretching spectrum is Figure 7As shown in the tensile mechanical properties test, the polymer exhibited an elongation at break of 600% and a tensile strength of approximately 5.2 MPa. After being stretched to 100% of its original length and cycled 10 times, its elastic recovery was measured to be approximately 91%, with a residual strain of approximately 7%. After use, the polymer was completely recovered by vacuum distillation using stannous octoate as a catalyst to obtain the monomers. This triblock copolymer, obtained through further polymerization, exhibited an elongation at break of 590% and a tensile strength of approximately 5.3 MPa.

[0047] Example 2

[0048] (0.05 mmol, 6.9 mg) 1,4-benzenedimethanol, (0.05 mmol, 7.5 μL) 1,8-diazabicyclo-7-undecene, (0.15 mmol, 52.2 mg) 1-(3,5-bis(trifluoromethyl)phenyl)-3-phenylurea Dissolve in 480 μL toluene and stir at room temperature for 5 minutes. Add (30 mmol, 3.3 mL) of β-methyl-δ-valerolactone to the reaction tube and react at 25 ° C under nitrogen protection for 5 hours. Then dissolve (15 mmol, 1.5 g) of p-dioxanone in 605 μL toluene and add it to the above system. React at 25 ° C under nitrogen protection for 40 minutes. Add 10 mg of benzoic acid to terminate the reaction. The reaction mixture is dissolved in 15 mL of chloroform and poured into 60 mL of methanol. Centrifuge and precipitate to obtain a polymer. The polymer is characterized by nuclear magnetic resonance as a triblock copolymer, namely poly-p-dioxanone-b-(poly-β-methyl-δ-valerolactone)-b-poly-p-dioxanone. The DSC spectrum is shown as follows. Figure 3 As shown, the stretching spectrum is Figure 7 As shown in the tensile mechanical properties test, the polymer elongation at break was 1174% and the tensile strength was about 15.8 MPa. After stretching to 100% of the original length and cycling 10 times, its elastic recovery was measured to be about 93% and the residual strain was about 6%. After use, the polymer was completely recovered by vacuum distillation using stannous octoate as a catalyst to obtain the monomer. The triblock copolymer was polymerized again under the same conditions, and its elongation at break was 1100% and the tensile strength was about 15.3 MPa. The recovered H-NMR spectrum is shown in the figure below. Figure 4 As shown in the figure, the tensile curve after cycling is Figure 6 shown.

[0049] Example 3

[0050] (0.1 mmol, 5.6 mL) ethylene glycol, (0.1 mmol, 1.5 μL) 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, (0.2 mmol, 56.1 mg) 1-phenyl-3-(4-(trifluoromethyl)phenyl)urea and 7.1 mL of dichloromethane were added to the reaction tube and stirred at room temperature for 10 min. (50 mmol, 5.5 mL) of β-methyl-δ-valerolactone was added to the reaction tube and the reaction was carried out at 29 ° C under nitrogen protection for 6 h. Then (40 mmol, 4.1 g) of p-dioxanone was dissolved in 6.6 mL of dichloromethane and added to the above system. The reaction was carried out at 40 ° C under nitrogen protection for 1 h, and 0.5 mL of dilute hydrochloric acid was added to terminate the reaction. The reaction mixture was dissolved in 30 mL of chloroform, poured into 240 mL of methanol, and centrifuged to separate the precipitate to obtain a polymer. The polymer was characterized by nuclear magnetic resonance as a triblock copolymer, namely poly-p-dioxanone-b-poly(β-methyl-δ-valerolactone)-b-poly-p-dioxanone. The DSC spectrum is shown as follows. Figure 3 As shown, the stretching spectrum is Figure 7 As shown in the tensile mechanical properties test, the polymer exhibited an elongation at break of 1297% and a tensile strength of approximately 20.7 MPa. After being stretched to 100% of its original length and cycled 10 times, its elastic recovery was measured to be approximately 85%, with a residual strain of approximately 9%. After use, the polymer was completely recovered by vacuum distillation using stannous octoate as a catalyst to obtain the monomers. This triblock copolymer, obtained through further polymerization, exhibited an elongation at break of 1310% and a tensile strength of approximately 22.3 MPa.

[0051] Example 4

[0052] (0.05 mmol, 2.8 mL) ethylene glycol, (0.05 mmol, 7.5 μL) 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, (0.20 mmol, 42.4 mg) 1,3-diphenylurea and 1.7 mL of chloroform were added to the reaction tube and stirred at room temperature for 10 min. (30 mmol, 3.3 mL) of β-methyl-δ-valerolactone was added to the reaction tube and the reaction was carried out at 19 ° C under nitrogen protection for 3 h. Then (15 mmol, 1.5 g) of p-dioxanone was dissolved in 1.2 mL of chloroform and added to the above system. The reaction was carried out at 40 ° C under nitrogen protection for 50 min. 1 mL of dilute sulfuric acid was added to terminate the reaction. The reaction mixture was dissolved in 50 mL of chloroform and poured into 180 mL of methanol. The polymer was centrifuged and precipitated to obtain a polymer. The polymer was characterized by nuclear magnetic resonance as a triblock copolymer, namely poly-p-dioxanone-b-poly(β-methyl-δ-valerolactone)-b-poly-p-dioxanone. The DSC spectrum is shown as follows. Figure 6 As shown, the stretching spectrum is Figure 8As shown in the tensile mechanical properties test, the polymer exhibited an elongation at break of 1100% and a tensile strength of approximately 15.6 MPa. After 10 cycles of stretching to 100% of its original length, its elastic recovery was measured to be approximately 93%, with a residual strain of approximately 10%. After use, the polymer was completely recovered by vacuum distillation using stannous octoate as a catalyst to obtain the monomers. This triblock copolymer, obtained through further polymerization, exhibited an elongation at break of 1090% and a tensile strength of approximately 15.3 MPa.

[0053] Example 5

[0054] (0.03 mmol, 1.7 mL) ethylene glycol, (0.03 mmol, 7.5 μL) phosphazene ligand P1-tert-butyl, (0.12 mmol, 33.7 mg) 1,3-bis(4-chlorophenyl)urea and 238 μL acetonitrile were added to the reaction tube and stirred at room temperature for 2 min. (15 mmol, 1.6 mL) β-methyl-δ-valerolactone was added to the reaction tube and the reaction was carried out at 20 ° C under nitrogen protection for 2 h. Then (7.5 mmol, 765 mg) p-dioxanone was dissolved in 304 μL acetonitrile and added to the above system. The reaction was carried out at 30 ° C under nitrogen protection for 45 min. 10 drops of acetic acid were added to terminate the reaction. The reaction mixture was dissolved in 25 mL of chloroform and poured into 150 mL of methanol. The polymer was centrifuged and precipitated to obtain a polymer. The polymer was characterized by nuclear magnetic resonance as a triblock copolymer, namely poly-p-dioxanone-b-poly(β-methyl-δ-valerolactone)-b-poly-p-dioxanone. The DSC spectrum is shown in FIG. Figure 6 As shown, the stretching spectrum is Figure 8 As shown in the tensile mechanical properties test, the polymer exhibited an elongation at break of 1189% and a tensile strength of approximately 10.3 MPa. After being stretched to 100% of its original length and cycled 10 times, its elastic recovery was measured to be approximately 89% and its residual strain was approximately 7%. After use, the polymer was completely recovered by vacuum distillation using stannous octoate as a catalyst to obtain the monomers. This triblock copolymer, obtained through further polymerization, exhibited an elongation at break of 1239% and a tensile strength of approximately 11.3 MPa.

[0055] Example 6

[0056] (0.4 mol, 5.5 g) 1,4-benzenedimethanol, (0.4 mol, 100 mL) phosphazene ligand P1-tert-butyl, (0.6 mol, 148.0 g) 1-(4-chlorophenyl)-3-phenylurea Dissolve in 2.5L tetrahydrofuran, stir at room temperature for 10min, add (160mol, 17.5L) β-methyl-δ-valerolactone to the reaction tube, and react at 25℃ under nitrogen protection for 3h. Then dissolve (80mol, 8160g) p-dioxanone in 3.2L tetrahydrofuran and add the above system, react at 30℃ under nitrogen protection for 30min, and add 200mL hydrochloric acid to terminate the reaction. The reaction mixture is dissolved in 85L chloroform, poured into 220L methanol, and centrifuged to obtain a polymer. The polymer is characterized by nuclear magnetic resonance as a triblock copolymer, namely poly(p-dioxanone-b-poly(β-methyl-δ-valerolactone)-b-poly(p-dioxanone). The tensile mechanical properties test shows that the polymer has an elongation at break of 683% and a tensile strength of about 5.8MPa. The DSC spectrum is as shown below. Figure 6 As shown, the stretching spectrum is Figure 8 As shown. After stretching to 100% of the original length and cycling 10 times, the elastic recovery rate was measured to be about 90% and the residual strain was about 7%. The DMA spectrum is shown as Figure 9 As shown, the storage modulus is always higher than the loss modulus, and its maximum operating temperature is 72.5°C. After use, the polymer can be completely recovered by vacuum distillation using stannous octoate as a catalyst to obtain the monomer, which is then polymerized again to obtain a triblock copolymer with an elongation at break of 657% and a tensile strength of approximately 5.9 MPa.

[0057] Example 7

[0058] (0.5 mol, 67.1 g) trimethylolpropane, (0.5 mol, 75 mL) 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, (1.0 mol, 212.2 g) 1,3-diphenylurea Dissolve in 4.7L tetrahydrofuran, stir at room temperature for 10min, add (300mol, 32.8L) β-methyl-δ-valerolactone to the reaction tube, and react at 0℃ under nitrogen protection for 6h. Then dissolve (150mol, 15.3kg) p-dioxanone in 6.1L tetrahydrofuran and add the above system, react at 25℃ under nitrogen protection for 30min, and add 100mL phosphoric acid to terminate the reaction. The reaction mixture is dissolved in 200L chloroform, poured into 300L methanol, and centrifuged to obtain a polymer. The polymer is characterized by nuclear magnetic resonance as a triblock copolymer, namely a three-arm star block copolymer (PβMδVL-PPDO)3. The tensile mechanical properties test shows that the polymer has an elongation at break of 1054% and a tensile strength of about 21.2MPa. It is stretched to 100% of its original length and cycled 10 times. Its elastic recovery rate is about 93% and the residual strain is about 6%. Its tensile cycle spectrum is as shown below Figure 10 DMA spectrum is shown as Figure 11As shown, the storage modulus is always higher than the loss modulus, and its maximum operating temperature is 81.3°C. After use, the polymer can be completely recovered by vacuum distillation using stannous octoate as a catalyst to obtain the monomer, which is then polymerized again to obtain a three-arm star-shaped block copolymer with an elongation at break of 1160% and a tensile strength of approximately 22.3 MPa.

Claims

1. ABA type triblock copolymer or (AB) x A star-shaped multi-arm block copolymer, wherein x≥2; characterized in that Segment A has a structure as shown in formula (I), and segment B has a structure as shown in formula (II): m is a natural number greater than or equal to 200, n is a natural number greater than or equal to 100, and m≥n.

2. The ABA type triblock copolymer according to claim 1 or (AB) x The method for preparing a star-shaped multi-arm block copolymer is characterized in that: The steps include: (1) Dissolve the initiator, organic base and urea in an organic solvent and stir at room temperature for 1 to 10 minutes; (2) adding β-methyl-δ-valerolactone to the above mixed solution and reacting at -20 to 60°C for 0.1 to 10 hours; (3) Add p-dioxanone to the above reaction system, continue the reaction at -20 to 60°C for 0.1 to 10 hours, and then add an acidic substance to terminate the reaction.

3. The method according to claim 2, characterized in that The urea has one of the following structures:

4. The method according to claim 2, characterized in that The initiator is a polyol selected from ethylene glycol, 1,2-propylene glycol, 1,2-butanediol, 1,4-butanediol, 1,4-cyclohexanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,2-benzenedimethanol, 1,3-benzenedimethanol, 1,4-benzenedimethanol, pentaerythritol, dipentaerythritol, and trimethylolpropane; the organic base is one of 1,8-diazabicyclo-7-undecene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, and phosphazene ligand P1-tert-butyl; and the organic solvent is toluene, tetrahydrofuran, dichloromethane, chloroform, acetonitrile, and N,N-dimethylformamide.

5. The method according to claim 2, characterized in that The molar ratio of the organic base to the initiator is 0.1 / 1 to 20 / 1; the molar ratio of the organic base to urea is 1 / 1 to 1 / 10.

6. The method according to claim 2, characterized in that The molar concentration of the β-methyl-δ-valerolactone in the system is 4 to 9.1 mol / L; the molar ratio of the β-methyl-δ-valerolactone to the initiator is 200 / 1 to 3000 / 1.

7. The method according to claim 2, wherein: The molar concentration of p-dioxanone in the system is 0.1-12.4 mol / L; the acidic substance is acetic acid, benzoic acid, hydrochloric acid, sulfuric acid or phosphoric acid; and the molar ratio of the acidic substance to the base is 1 / 1-10 / 1.

8. The ABA type triblock copolymer according to claim 1 or (AB) x The circulation method of the star-shaped multi-arm block copolymer comprises the following steps: (1) mixing a thermoplastic elastomer with stannous octoate, heating at 100-200° C. for 2-10 hours, and distilling under reduced pressure to obtain a high-purity mixture of p-dioxanone and β-methyl-δ-valerolactone; (2) The mixture is separated to obtain p-dioxanone and β-methyl-δ-valerolactone, which are then repolymerized to obtain an ABA type triblock copolymer or (AB) x Star-shaped multi-arm block copolymers.

9. The ABA type triblock copolymer according to claim 1 or (AB) x Application of star-shaped multi-arm block copolymers in thermoplastic elastomers.

Images