Long-chain star-shaped hyperbranched terpolymers, thermoreversible dynamic cross-linked thermoplastic elastomers and preparation thereof

Abstract

The application discloses a long-chain star-shaped hyperbranched terpolymer, a thermoreversible dynamic crosslinking thermoplastic elastomer and a preparation method of the thermoplastic elastomer. The long-chain star-shaped hyperbranched terpolymer is prepared by the following method: a macromolecular initiator containing a terminal bromine is obtained by catalyzing copolymerization of ethylene and BIEA monomers by a Pd-diimine catalyst through a chain walking mechanism; and the long-chain star-shaped hyperbranched terpolymer is synthesized by using the macromolecular initiator as an initiator, furfuryl methacrylate and styrene as comonomers, PMDETA as a ligand and CuBr as a catalyst through atom transfer radical polymerization. The application provides a thermoplastic elastomer which is obtained by crosslinking and curing of the long-chain star-shaped hyperbranched terpolymer and a curing agent. The application introduces furan groups into hyperbranched polyethylene, realizes dynamic reversible covalent bond modification, and makes the thermoplastic elastomer have a thermoreversible property, thereby promoting recycling and secondary use of the material.

Description

Technical Field

[0001] This invention relates to a long-chain hyperbranched star copolymer HBPE@P(SrF), an HBPE@P(SrF)-based thermoplastic elastomer with thermo-induced reversible dynamic crosslinking properties, and a method for preparing the same. Background Technology

[0002] Thermoplastic elastomers (TPEs) are a class of reprocessable elastomeric materials that possess rubber-like elasticity at room temperature and, due to the presence of physical cross-linking points, can be plasticized and molded at high temperatures. TPEs are widely used in all aspects of life, playing an indispensable role in material encapsulation, building decoration, and the medical and health fields. General-purpose thermoplastic elastomers, represented by styrene, polyurethane, and diene types, have seen significant development due to their excellent flexibility, high elasticity, and wide range of applications. However, compared to vulcanized rubber, TPE materials typically exhibit lower mechanical strength and poorer solvent resistance due to the lack of chemical bonds between molecular chains. In contrast, traditional rubber also has a serious drawback: after curing, the strong bonding leads to tight connections between molecular chains, making the material unusable once damaged. Therefore, how to improve the mechanical properties and solvent resistance of thermoplastic elastomers without affecting their secondary processing and reuse presents a new challenge for the development of novel thermoplastic elastomers.

[0003] Based on this goal, a series of reversible dynamic bonds have been developed and reported, mainly including: (1) Hydrogen bonds: relying on the strong hydrogen bond network formed between molecular chains or between molecular chains and small molecule functional groups to enhance various properties. As the temperature increases, the hydrogen bonds are broken, the cross-linking network is broken, thereby realizing the transformation from thermosetting to thermoplastic. (2) Metal coordination: coordinating metal ions (Fe 3+ Cu 2+ (2) Metal chelates with different coordination degrees can be formed by polar groups (-OH, -COOH) under different pH conditions. By adjusting the acidity and alkalinity of the system, the binding ability of the polymer can be changed. (3) Ion interaction: Ion pairs are formed by the mutual attraction of cations and anions. The interaction weakens under heating conditions, and the ion pair network can be reconstructed at room temperature, thereby realizing the reversible properties of the material. In contrast, the reversible network formed by non-covalent interaction still has a certain gap with the elastomer prepared by reversible covalent bonds in terms of mechanical strength, solvent resistance and dimensional stability. Therefore, modifying the polymer molecular chain with reversible covalent bonds is an effective method to prepare high mechanical strength reversible thermoplastic elastomers. Summary of the Invention

[0004] The purpose of this invention is to provide a long-chain star-shaped hyperbranched terpolymer HBPE@P(SrF), an HBPE@P(SrF)-based thermoplastic elastomer with thermo-induced reversible dynamic crosslinking properties, and a method for preparing the same.

[0005] The technical solution of the present invention will be described in detail below.

[0006] In a first aspect, the present invention provides a long-chain star-shaped hyperbranched terpolymer HBPE@P(SrF), which is prepared by the following method: using a Pd-diimine catalyst to catalyze the copolymerization of ethylene and 2-(2-bromoisobutyryloxy)ethyl acrylate (BIEA) monomers via a "chain walk" mechanism to obtain a macromolecular initiator HBPE@Br containing terminal bromine; then using HBPE@Br as the initiator, furfuryl methacrylate (FMA) and styrene (St) as comonomers, pentamethyldiethylenetriamine (PMDETA) as the ligand, and CuBr as the catalyst, the long-chain star-shaped hyperbranched terpolymer HBPE@P(SrF) is synthesized by atom transfer radical polymerization (ATRP).

[0007] Secondly, the present invention provides a method for preparing a long-chain star-shaped hyperbranched terpolymer HBPE@P(SrF), the specific operation steps of which are as follows:

[0008] (1) Under the protection of ethylene atmosphere, add 2-(2-bromoisobutyryloxy)ethyl acrylate (BIEA), Pd-diimine catalyst and anhydrous reagent to the reaction vessel, stir thoroughly and control the temperature at 15-35℃, react for 12-24h under ethylene pressure of 0.01-0.1MPa, and then obtain the macromolecular initiator HBPE@Br containing terminal bromine after separation and purification;

[0009] (2) Under nitrogen protection, using HBPE@Br obtained in step (1) as an initiator, furfuryl methacrylate (FMA) and styrene (St) as comonomers, pentamethyldiethylenetriamine (PMDETA) as ligand, and CuBr as catalyst, the reaction was carried out in anhydrous toluene at 80-100℃ for 5-12h. After polymerization, the long-chain star-shaped hyperbranched terpolymer HBPE@P(SrF) was obtained by separation and purification.

[0010] In the synthesis of HBPE@Br, the anhydrous reagent is preferably one of the following: anhydrous dichloromethane, chloroform, or chlorobenzene.

[0011] In the preparation process of HBPE@Br described above, the Pd-diimine catalyst is preferably one of the following: acetonitrile-based Pd-diimine catalyst 1, or a six-membered ring Pd-diimine catalyst 2 containing a methyl ester group, the structural formulas of which are shown below:

[0012]

[0013] in,

[0014] Both of the above Pd-diimine catalysts can be synthesized in the laboratory with reference to the following literature:

[0015] [1] Johnson LK, Killian CM, Brookhart MJAm.Chem.Soc., 1995, 117, 6414; [2] Johnson LK, Mecking S., Brookhart MJAm.Chem.Soc., 1996, 118, 267.

[0016] Preferably, in step (1), the initial concentration of 2-(2-bromoisobutyryloxy)ethyl acrylate in the polymerization system is 0.1-1.0 mol / L; and the mass amount of the Pd-diimine catalyst is 3-34% of the mass amount of 2-(2-bromoisobutyryloxy)ethyl acrylate.

[0017] Preferably, in step (1), the reaction temperature is 20-30℃, the ethylene pressure is 0.1MPa, and the reaction time is 20-24h.

[0018] Preferably, in step (1), the separation and purification method is carried out as follows: the reaction mixture solution is directly exposed to air, continuously stirred and purged with cold air to remove the solvent, thereby terminating the polymerization and obtaining a polymer containing impurities; an appropriate amount of THF is added to dissolve the above mixture, and a small amount of hydrochloric acid and hydrogen peroxide are added respectively to stir the reaction thoroughly for 1-5 hours to remove the small amount of Pd particles mixed in the product; then the solvent is removed by purging with cold air again, and THF is added again to just completely dissolve the product. When a polymer saturated solution is formed, methanol is added dropwise to precipitate the product until the supernatant is clear and transparent (the volume of methanol added is 2-20 times that of THF). Further, the upper layer solution is removed to obtain the precipitate, and THF is used to dissolve it again; this process (THF dissolution-methanol precipitation) is repeated 2-3 times to obtain the purified polymer, and finally it is vacuum dried to obtain the final product HBPE@Br. As for step (2), the separation and purification method is largely the same as that in step (1), except that HCl and H2O2 are not added to remove Pd black in the process, which will not be described in detail here.

[0019] In step (2) of this invention, the comonomer needs to be purified before use.

[0020] Preferably, in step (2), the molar ratio of HBPE@Br, furfuryl methacrylate, styrene, pentamethyldiethylenetriamine, and CuBr is 1:5-80:50-500:0.1-100:0.01-100, more preferably 1:5-15:150-250:1-5:0.5-2, wherein the molar amount of HBPE@Br is calculated based on the molar amount of Br contained therein.

[0021] Preferably, in step (2), the initial concentration of styrene in the reaction system is 2.0-20.0 mol / L.

[0022] Preferably, in step (2), the reaction temperature is 90°C and the reaction time is 6 hours.

[0023] Thirdly, the present invention provides an HBPE@P(SrF)-based thermoplastic elastomer, which is obtained by crosslinking and curing the long-chain star-shaped hyperbranched terpolymer HBPE@P(SrF) and a curing agent, wherein the curing agent is at least one selected from 4,4'-methylene bis(N-phenylmaleimide) (BMI), bismaleimide, and succinimide 6-(maleimino)hexanoate.

[0024] Preferably, the cross-linking curing reaction is carried out in an organic solvent, and the cross-linking curing process is carried out in an environment of 25-80°C for 3-5 days.

[0025] As a further preferred option, the organic solvent is selected from one of the following chemically pure or analytically pure solvents: dichloromethane, chloroform, toluene, xylene, or o-dichlorobenzene.

[0026] Preferably, the mass of the curing agent is 0.5%-3% of the mass of the long-chain star-shaped hyperbranched terpolymer HBPE@P(SrF).

[0027] Fourthly, the present invention provides a method for preparing an HBPE@P(SrF)-based thermoplastic elastomer, the method comprising:

[0028] (a) Obtaining a long-chain star-shaped hyperbranched terpolymer HBPE@P(SrF);

[0029] (b) Take the long-chain star-shaped hyperbranched terpolymer HBPE@P(SrF) and the curing agent and dissolve them in an organic solvent to obtain a pre-cured solution; the curing agent is at least one of 4,4'-methylene bis(N-phenylmaleimide) (BMI), bismaleimide, and succinimide 6-(maleimino)hexanoate.

[0030] (c) The pre-curing solution prepared in step (1) is cross-linked and cured in an environment of 25-80°C for 3-5 days to obtain DA cross-linked HBPE@P(SrF) based thermoplastic elastomer.

[0031] The operation of step (a) of the present invention is the same as that in the second aspect, and will not be repeated here.

[0032] In step (b) of the present invention, if the substrate is to be joined, the pre-curing solution in step (a) is simply applied to the surface of the substrate by solution casting, and the initially joined substrate is further cross-linked and cured.

[0033] Preferably, in step (b), the organic solvent is selected from one of the following chemically pure or analytically pure solvents: dichloromethane, chloroform, toluene, xylene, and o-dichlorobenzene. More preferably, the organic solvent is selected from one of the following chemically pure or analytically pure solvents: dichloromethane and chloroform.

[0034] Preferably, in step (b), the concentration of the long-chain star-shaped hyperbranched terpolymer HBPE@P(SrF) in the pre-curing solution is 50-500 mg / mL, more preferably 80-300 mg / mL; and the mass of the curing agent is 0.5%-3% of the mass of the long-chain star-shaped hyperbranched terpolymer HBPE@P(SrF), more preferably 1%-2%.

[0035] Preferably, in step (c), the cross-linking curing temperature is 30°C and the cross-linking curing time is 5 days.

[0036] The HBPE@P(SrF)-based thermoplastic elastomer prepared by this invention is a crosslinked polymer containing DA bonds and exhibits thermo-induced reversible dynamic crosslinking characteristics. Heat treatment of the prepared HBPE@P(SrF)-based thermoplastic elastomer can cause the DA bonds to dissociate, after which it can be re-dissolved in an organic solvent to obtain a pre-cured solution of the elastomer. Preferably, the heat treatment conditions are: heating at 125-160℃ for 5-60 minutes.

[0037] The present invention has the following outstanding advantages and beneficial effects compared with the prior art:

[0038] 1. This invention utilizes a Pd-diimine catalyst to catalyze the copolymerization of ethylene and other olefin monomers via a "chain-walking" mechanism, combined with atom transfer radical polymerization (ATRP) technology, to prepare long-chain star-shaped hyperbranched copolymers. Their unique topological structure endows them with the characteristics of both hyperbranched polymers (lower solution / melt viscosity, high solubility) and linear polymers (high mechanical strength), making them an ideal material for preparing high-performance thermoplastic elastomers.

[0039] 2. This invention introduces furan groups into hyperbranched polyethylene to achieve dynamic and reversible covalent bond modification, enabling the designed and synthesized HBPE@P(SrF)-based thermoplastic elastomer to have thermally reversible properties. It can achieve the transformation between thermosetting and thermoplastic polymers at a certain temperature, thereby promoting the recycling and reuse of materials and contributing to the sustainable development of society. Attached Figure Description

[0040] Figure 1 A schematic diagram illustrating the synthesis principle of macromolecular initiator HBPE@Br and long-chain star-shaped hyperbranched terpolymer HBPE@P(SrF);

[0041] Figure 2 A schematic diagram illustrating the preparation and reuse of an HBPE@P(SrF)-based thermoplastic elastomer;

[0042] Figure 3 (a) Macromolecular initiator HBPE@Br and (b) HBPE@P(SrF) 1 (c) HNMR spectra of HBPE@Br and HBPE@P(SrF); (d) Physical images of HBPE@Br and HBPE@P(SrF);

[0043] Figure 4 DSC curves of pure HBPE@P(SrF), HBPE@P(SrF) initial cured samples and their recycled cured samples: (a) first heating, (b) second heating;

[0044] Figure 5 FT-IR of pure HBPE@P(SrF), HBPE@P(SrF) initially cured samples and their recycled cured samples;

[0045] Figure 6 Stress-strain curves of HBPE@P(SrF) and its cured samples;

[0046] Figure 7Thermal properties of HBPE@P(SrF) and its cured samples: (a) Storage modulus (G') and loss modulus (G") as a function of temperature; (b) Loss tangent as a function of temperature; (c) Complex viscosity as a function of temperature.

[0047] Figure 8 (a) HBPE@PS and (b) P(SrF) 1 HNMR spectrum; (c) GPC curves of HBPE@PS and P(SrF);

[0048] Figure 9 (a) Shear strength of different polymers on glass substrates and (b) magnified view of a portion thereof;

[0049] Figure 10 HBPE@P(SrF) cured samples were immersed in CH2Cl2 at room temperature (1-1), and after heating at 160℃ for 5 min, the HBPE@P(SrF) samples redissolved in CH2Cl2 (1-2). HBPE@P(SrF) / BMI cured at 30℃ for 5 days swelled in CH2Cl2 (1-3).

[0050] Figure 11 Tensile stress-strain curves of initially cured and reusable elastomers. Detailed Implementation

[0051] The specific implementation process of this invention will be further described below, but its implementation is not limited to this.

[0052] Example 1

[0053] 1. Sample preparation

[0054] (1) The sample preparation in Example 1 was carried out as follows:

[0055] Step 1: Take a clean and thoroughly dry 100mL Schlenk flask. Under an ethylene atmosphere, add 10mL of anhydrous dichloromethane and 6mmol of BIEA monomer (1.8g) using a syringe, and maintain the temperature at 25℃ while stirring thoroughly for 30min. Then, add acetonitrile-based Pd-diimine catalyst 1 (200mg) pre-dissolved in 10mL of anhydrous dichloromethane, and react under light for 24h at an ethylene pressure of 0.1MPa. After the polymerization reaction is complete, expose the mixed solution containing the product to air and dry the solvent with cold air. Then, add approximately 20mL of THF to dissolve the polymer, followed by the addition of 36-38% HCl and 30% H2O2 (6-10 drops each), and stir thoroughly for approximately 3h to remove Pd black impurities. Further, the solvent was dried again with cold air, and then a certain amount of THF (15 mL) was added to just dissolve the polymer. Subsequently, methanol (50 mL in total) was added dropwise to precipitate the polymer. Once no more polymer precipitated from the upper layer, the upper layer was removed, and the polymer was completely dissolved again with THF (15 mL). The above process (THF dissolution-methanol precipitation) was repeated three times. The resulting polymer was placed in a vacuum oven at 60 °C for 48 h to finally obtain the macromolecular initiator HBPE@Br.

[0056] Step 2: Purification of ATRP polymerization comonomer: Take a clean 500mL separatory funnel and add 200mL of styrene monomer (St) and an equal volume of 5wt% NaOH solution. Shake vigorously for 3 minutes, let stand for 30 minutes, and then remove the aqueous layer. Repeat the above washing process three times until the aqueous layer becomes colorless. Then, add an equal volume of deionized water, shake vigorously for 3 minutes, let stand for 30 minutes, remove the aqueous layer, and repeat the above operation 4 times until the styrene is finally neutral. Then, add about 20g of anhydrous CaCl2 to the styrene, seal and stir overnight (about 12h), filter to remove CaCl2, and obtain the purified styrene monomer by vacuum distillation (with 5g of CaH2 added), and store in a sealed container protected from light. The purification process for furfuryl methacrylate is the same as above.

[0057] Step 3: Take a strictly dry 100mL Schlenk flask and, under a nitrogen atmosphere, add HBPE@Br (0.8g, 0.52mmol Br), St (98.8mmol), FMA (5.2mmol), PMDETA (1.04mmol), and 12mL anhydrous toluene, mixing thoroughly. Next, the mixture is subjected to a freeze-vacuum-thaw cycle three times to remove oxygen. Then, under nitrogen protection, CuBr (0.52mmol) is added, the temperature is set at 90℃, and the polymerization time is 6h. After polymerization, the polymer solution is placed in a beaker, the solvent is dried with cold air, and dissolved with 15mL THF. Methanol is added dropwise (approximately 45mL in total) to precipitate the product, and the supernatant is removed. This purification process is repeated three times to obtain the precipitated product. Finally, the product is placed in a 30℃ vacuum oven to remove residual solvent, yielding the long-chain star-shaped hyperbranched terpolymer HBPE@P(SrF).

[0058] 2. Characterization and Testing

[0059] (1) Proton nuclear magnetic resonance spectrum 1 HNMR)

[0060] The polymers HBPE@Br and HBPE@P(SrF) 1 All H NMR measurements were performed using a 500MHz AVANCE III nuclear magnetic resonance spectrometer (Bruker, Switzerland), with deuterated chloroform as the solvent and a test temperature of 25℃.

[0061] (2) Gel permeation chromatography (GPC) analysis

[0062] The absolute molecular weight of the polymer was obtained using an OMNISEC gel permeation chromatograph (Malvern, UK) with a refractive index and light scattering detector coupled. Before testing, the sample was prepared into a 4-6 mg / mL solution with THF. The test temperature was 35℃, and PS was used as the standard.

[0063] 3. Comparison and Analysis of Test Results

[0064] Figure 3 (a) and (b) respectively give the results for HBPE@Br and HBPE@P(SrF). 1 ¹H NMR spectra. Figure (a) confirms that isobutyryl bromide groups have been successfully grafted onto hyperbranched polyethylene, with a grafting rate of 2.2 mol% (0.65 mmol / g), meaning 2.2 terminal bromine groups per 100 ethylene structural units. Meanwhile, Figure (b) concludes that styrene monomer and furan groups have been successfully introduced into hyperbranched polyethylene, with grafting rates of 79.6 mol% and 0.6 mol%, respectively. Figure 3(c) The molecular weights of HBPE@Br and HBPE@P(SrF) were characterized. Compared to HBPE@Br, the ATRP curve of HBPE@P(SrF) shifted to the left and exhibited a bimodal distribution, indicating that HBPE@P(SrF) has a larger molecular weight and a wider molecular weight distribution. These differences can also be attributed to... Figure 3 (d) Further confirmation shows that it exhibits the state of HBPE@Br and HBPE@P(SrF) at room temperature. After ATRP, the polymer changes from the original viscous flow state to a solid state, which indirectly confirms the successful grafting of furan groups and styrene.

[0065] Example 2, Comparative Examples 1-4

[0066] 1. Sample preparation

[0067] (1) The sample in Example 2 was prepared as follows:

[0068] Preparation of HBPE@P(SrF)-based thermoplastic elastomer: First, weigh 1g of the long-chain star-shaped hyperbranched terpolymer HBPE@P(SrF) (containing 0.05mmol furan groups) prepared in Example 1 and 9mg of 4,4'-methylenebis(N-phenylmaleimide) (BMI) into a container, add 11.2mL of CH2Cl2, and stir to mix and dissolve thoroughly. Then, place the container open in an oven at 30℃ for crosslinking and curing for 5 days to obtain the HBPE@P(SrF)-based elastomer.

[0069] (2) The preparation of the sample for Comparative Example 1 was carried out as follows:

[0070] The final product HBPE@P(SrF) synthesized in Example 1 was used.

[0071] (3) The preparation of the sample for Comparative Example 2 was carried out as follows:

[0072] Step 1: Solvent-free hyperbranched crosslinked polymer recycling: Collect the HBPE@P(SrF)-based elastomer prepared in Example 2, and let it stand at 160°C for 5 min. The DA bond will dissociate, and the generated HBPE@P(SrF) and BMI can be redissolved in CH2Cl2.

[0073] Step 2: Place the mixed solution obtained in Step 1 in an oven at 30°C for cross-linking and curing for 5 days to obtain the HBPE@P(SrF) matrix elastomer that was cured after the first use.

[0074] (4) The samples of Comparative Example 3 were prepared as follows:

[0075] The preparation steps are the same as in Comparative Example 2, and will not be repeated here. The difference is that the first step uses the recycled first-cured HBPE@P(SrF)-based elastomer obtained in Comparative Example 2. Finally, the recycled second-cured HBPE@P(SrF)-based elastomer is obtained.

[0076] (5) The samples of Comparative Example 4 were prepared as follows:

[0077] The preparation steps were the same as in Comparative Example 2, and will not be repeated here. The difference was that the first step used the second-cured HBPE@P(SrF)-based elastomer obtained in Comparative Example 3. Finally, the third-cured HBPE@P(SrF)-based elastomer was obtained.

[0078] 2. Characterization and Testing

[0079] (1) Differential Scanning Calorimetry (DSC)

[0080] DSC curves of HBPE@P(SrF) and HBPE@P(SrF) based elastomers were obtained using a DSC214 instrument (Netzsch, Germany), with a test temperature range of 25-160℃. Under nitrogen atmosphere and programmed temperature control, the samples were heated to 160℃ at a rate of 5℃ / min, held at that temperature for 3 min, then rapidly cooled (50℃ / min) to 25℃, and held at that temperature for another 3 min. The temperature was then again increased to the maximum temperature at the same rate.

[0081] (2) Total reflectance infrared spectroscopy test (ATR-FTIR)

[0082] The infrared spectrum of the polymer was measured using a Nicolet 6700 Fourier transform infrared spectrometer (Nicolet Corporation, USA). The scanning range was 4000-400 cm⁻¹. -1 The resolution is 4cm. -1 All samples were dried to remove moisture before testing.

[0083] 3. Comparison and Analysis of Test Results

[0084] The DSC curves of HBPE@P(SrF) and HBPE@P(SrF) matrix elastomers in Examples 2 and Comparative Examples 1-4 are shown below. Figure 4 As shown. Figure 4 Figures (a) and (b) show the first and second heating curves, respectively. As can be seen from Figure (a), slight crosslinking affects the polymer's glass transition temperature (Tg). g No significant effect was observed (T) g=60℃). However, unlike pure HBPE@P(SrF), the polymer network of both initially cured and recycled HBPE@P(SrF)-based elastomers exhibits a relatively weak endothermic peak at 125-130℃. This is because the breaking of the polymer DA bonds at high temperatures causes the crosslinking to dissociate, indicating that the elastomer has the ability to undergo repeated pyrolysis-curing. Furthermore, after rapid cooling and subsequent reheating of the sample, as shown in Figure (b), the endothermic peak of the HBPE@P(SrF)-based elastomer at around 125℃ disappears. This indicates that the crosslinked polymer does not rapidly crosslink after thermal dissociation, providing favorable conditions for the recycling and reuse of HBPE@P(SrF).

[0085] The reversible cycling capability of HBPE@P(SrF) was further confirmed by infrared spectroscopy. Figure 5 It can be seen that, using HBPE@P(SrF) without BMI as a control, all three HBPE@P(SrF) matrix elastomer samples after initial curing and reuse exhibit a characteristic peak (1719 cm⁻¹) of DA ring formation. -1 After dissociation at 160℃, the characteristic peak at that position becomes weak, indicating that the DA ring is destroyed at a certain temperature.

[0086] Example 3, Comparative Example 5

[0087] 1. Sample preparation

[0088] (1) The sample in Example 3 was prepared as follows:

[0089] Preparation of lap-jointed shear tensile specimens: 180 mg of HBPE@P(SrF) prepared in Example 1 and 1.6 mg of curing agent (BMI) were placed in a glass bottle, and 2 mL of CH2Cl2 was added and thoroughly mixed to prepare a 90 mg / mL solution. The solution was then dripped onto a glass substrate using a solution casting method to form a sandwich-structured tensile specimen, with the middle layer being an HBPE@P(SrF)-based thermoplastic elastomer layer, and an overlap area of ​​20 mm × 25.6 mm. The specimen was then placed in a 30°C oven for cross-linking and curing for 5 days to obtain the final test sample.

[0090] (2) The sample in Comparative Example 5 was prepared as follows:

[0091] The preparation process for the lap shear performance test samples is the same as in Example 3 above, and will not be repeated here. The difference is that the curing agent BMI was not added during the preparation process.

[0092] 2. Characterization and Testing

[0093] The lap shear properties were tested using an Instron 5966 high and low temperature double column tester (Instron Corporation, USA), with a tensile rate of 5 mm / min.

[0094] 3. Comparison and Analysis of Test Results

[0095] To confirm the effect of crosslinking on mechanical properties, an overlap shear test was used for characterization. The shear property test results of the samples prepared in Example 3 and Comparative Example 5 are as follows: Figure 6 As shown, HBPE@P(SrF) without curing agent exhibits a relatively weak shear strength (0.20 MPa). In contrast, the shear properties of HBPE@P(SrF)-based thermoplastic elastomer after DA crosslinking are significantly improved (2.25 MPa), which is about 12 times that before curing.

[0096] Example 4, Comparative Example 6

[0097] 1. Sample preparation

[0098] (1) The sample in Example 4 was prepared as follows:

[0099] Rheological test sample preparation: The polymer tested in Example 3 was recovered and ground into powder.

[0100] (2) The sample in Comparative Example 6 was prepared as follows:

[0101] The preparation process of the rheological test samples was the same as in Example 4 above, and will not be repeated here. The difference is that the recovered polymer came from Comparative Example 5.

[0102] 2. Characterization and Testing

[0103] Rheological tests were conducted using an HR-20 rotational rheometer (TA Instruments, Inc., USA). Each test sample was approximately 500 mg, with a gap value of 1 mm, a heating rate of 3 °C / min, a frequency of 1 Hz, and a test temperature range of 120-160 °C.

[0104] 2. Comparison and Analysis of Test Results

[0105] To further demonstrate the effect of crosslinking on the polymer's modulus enhancement, rheological characterization was performed on samples of the elastomer before and after crosslinking. Figure 7(a) It can be seen that after crosslinking, the heat resistance of the polymer will increase to a certain extent. Compared with HBPE@P(S-r-F), the temperature at which the HBPE@P(S-r-F)-based thermoplastic elastomer changes from the viscoelastic state (G'>G") to the viscous flow state (G'<G") shifts 5°C towards the high-temperature direction. When the temperature exceeds 137°C, as the temperature increases, the storage modulus and loss modulus of the HBPE@P(S-r-F)-based thermoplastic elastomer decrease slowly, while the pure HBPE@P(S-r-F) starts to show a sharp decline. This can also be seen from the change in the loss tangent value of the figure ( Figure 7 (b)). At the same time, according to Figure 7 (c), the HBPE@P(S-r-F)-based thermoplastic elastomer has a higher complex viscosity at lower temperatures. As the temperature increases (150°C), its complex viscosity finally becomes the same as that of the pure HBPE@P(S-r-F), indicating that the polymer crosslinking network has good melt processing ability at high temperatures.

[0106] Comparative Examples 7-9

[0107] 1. Preparation of Samples

[0108] (1) The sample in Comparative Example 7 was obtained as follows:

[0109] The sample in Comparative Example 7 was commercial PS with a number-average molecular weight of 9000 - 100000 g / mol, purchased from North Huajin Chemical Industry Co., Ltd.

[0110] (2) The polymer HBPE@PS involved in Comparative Example 8 was synthesized in the laboratory, and the specific steps are as follows:

[0111] HBPE@Br was synthesized according to the first step of Example 1, and HBPE@PS was synthesized via ATRP. First, a strictly dry 100 mL Schlenk flask was used, and the initiator HBPE@Br (0.8 g, 0.52 mmol Br), monomer St (104 mmol), ligand PMDETA (1.04 mmol), and an equal volume of anhydrous toluene (12 mL) were added and dissolved completely. The mixture was then subjected to a freeze-vacuum-thaw cycle three times. The catalyst CuBr (0.52 mmol) was added, and the reaction was carried out at 90 °C for 6 h. After the reaction, the solvent in the mixture was removed by cold purging. An appropriate amount of THF (10 mL) was added to dissolve the polymer, followed by dropwise addition of methanol (approximately 45 mL in total) to allow the polymer to gradually precipitate. Once no polymer precipitation occurred, the supernatant was removed, and THF was added dropwise again for dissolution. This purification process (THF dissolution-methanol precipitation) was repeated three times to obtain polymer containing residual dissolution. Finally, the obtained product was subjected to vacuum treatment (48h, 60℃) to obtain the product HBPE@PS.

[0112] (3) The linear P(SrF) synthesis steps in Comparative Example 9 are as follows:

[0113] In a clean 100 mL Schlenk flask, ethyl 2-bromoisobutyrate (EBiB, 0.52 mmol), monomers St (98.8 mmol) and FMA (5.2 mmol), ligand PMDETA (1.04 mmol), and anhydrous toluene (12 mL) were added sequentially and stirred thoroughly to dissolve. The mixture was then subjected to a freeze-vacuum-thaw cycle three times, and CuBr (0.52 mmol) was added. The reaction was carried out at 90 °C for 24 h. The polymer was then purified using the same process as HBPE@PS, ultimately yielding a styrene-furfuryl methacrylate copolymer P(SrF).

[0114] The preparation of the lap shear performance test strips of PS, HBPE@PS, and P(SrF) is the same as in Example 3, and will not be repeated here. The difference is that the curing agent BMI was not added to PS and HBPE@PS.

[0115] 2. Characterization and Testing

[0116] (1) Nuclear magnetic resonance hydrogen spectrum test 1 H NMR)

[0117] See Example 1.

[0118] (2) Gel permeation chromatography (GPC) analysis

[0119] See Example 1.

[0120] (3) Overlap shear performance test

[0121] See Example 3.

[0122] 3. Comparison and Analysis of Test Results

[0123] To verify the effect of introducing hyperbranched polyethylene on the shear properties of polymer-based thermoplastic elastomers, linear P(SrF) and HBPE@PS were synthesized and their shear strengths were compared. 1 The H NMR spectrum is as follows Figure 8 As shown in (a) and 8(b), it can be confirmed that HBPE@PS and P(SrF) have been successfully synthesized. Meanwhile, as... Figure 8 As shown in (c), even with a several-fold increase in polymerization time, the molecular weight of linear P(SrF) remains relatively low compared to HBPE@P(SrF), and its molecular weight distribution is wider (PDI = 2.89), indicating significant chain transfer. Therefore, hyperbranched polyethylene has the effect of coupling linear P(SrF), thereby increasing the polymer's molecular weight and crosslinking density. Shear tests were performed on different polymers, such as... Figure 9 (a) and its partial magnification Figure 9 (b) Linear P(SrF) has almost no shear strength after curing. In addition, commercial PS and laboratory-synthesized HBPE@PS have only low shear strength. Only HBPE@P(SrF) has excellent shear strength (2.25MPa) after curing. The specific values ​​are shown in Table 1 below.

[0124] Table 1

[0125]

[0126] Note: The HBPE@P(SrF) cured sample in Table 1 is the HBPE@P(SrF) based thermoplastic elastomer test sample obtained in Example 3.

[0127] Example 5, Comparative Examples 10-11

[0128] 1. Sample preparation

[0129] (1) The samples involved in Example 5 were prepared as follows:

[0130] Preparation of HBPE@P(SrF) initial cured reuse sample tensile specimens: 180 mg of HBPE@P(SrF) based thermoplastic elastomer prepared in Example 3 was weighed into a container and heat-treated at 160°C for 5 min. Then 2 mL of CH2Cl2 was added to dissolve the polymer. Subsequently, the sandwich structure tensile specimens were prepared again according to the steps in Example 3.

[0131] (2) The sample in Comparative Example 10 was obtained in the same manner as in Example 5, and will not be described again here. The difference is that the sample recovered for heat treatment was the polymer tested in Example 5.

[0132] (3) The sample in Comparative Example 11 was obtained in the same manner as in Example 5, and will not be repeated here. The difference is that the sample recovered for heat treatment was the polymer tested in Comparative Example 10.

[0133] 2. Characterization and Testing

[0134] The overlap shear test was performed according to the method (1) in the characterization and testing in Example 3.

[0135] 3. Comparison and Analysis of Test Results

[0136] To verify the thermal reversibility and recyclability of HBPE@P(SrF)-based thermoplastic elastomers, a series of solubility and shear performance tests were conducted. Firstly, as... Figure 10 As shown, after the cross-linking reaction, HBPE@P(SrF) could not dissolve in CH2Cl2 after 24 hours of soaking. However, after heat treatment (160℃, 5 min), the cross-linked polymer re-dissolved in CH2Cl2 through pyrolysis. Finally, after a long curing period (30℃, 5 days), the polymer again exhibited the phenomenon of swelling but not dissolving in CH2Cl2. Subsequently, tensile specimens were prepared and tested on the recycled polymer samples. The stress-strain curves of the polymer after initial curing and 1-3 reuses are shown in the figure. Figure 11 As shown, the DA-cured HBPE@P(SrF)-based elastomer exhibits strong shear strength, reaching up to approximately 2.25 MPa. Even after three reuses, its shear strength remains above 2 MPa, consistently maintaining a performance level above 90% of the initial curing stage. This indicates that the lap shear strength of the HBPE@P(SrF)-based thermoplastic elastomer did not significantly decrease after reuse. In summary, this polymer possesses recyclability and reusability capabilities, as detailed in Table 2 below.

[0137] Table 2

[0138]

Claims

1. A long-chain star-shaped hyperbranched terpolymer HBPE@P(SrF), characterized in that: The long-chain star-shaped hyperbranched terpolymer HBPE@P(SrF) was prepared by the following method: ethylene and 2-(2-bromoisobutyryloxy)ethyl acrylate monomers were copolymerized using a Pd-diimine catalyst via a "chain-walking" mechanism to obtain a macromolecular initiator HBPE@Br containing terminal bromine; then, using HBPE@Br as the initiator, furfuryl methacrylate and styrene as comonomers, pentamethyldiethylenetriamine as the ligand, and CuBr as the catalyst, the long-chain star-shaped hyperbranched terpolymer HBPE@P(SrF) was synthesized by atom transfer radical polymerization.

2. A method for preparing the long-chain star-shaped hyperbranched terpolymer HBPE@P(SrF) as described in claim 1, characterized in that: The specific steps of the preparation method are as follows: (1) Under the protection of an ethylene atmosphere, add ethyl acrylate-2-(2-bromoisobutyryloxy)acrylate, Pd-diimine catalyst and anhydrous reagent to the reaction vessel, stir thoroughly and control the temperature at 15°C. At 35 ℃, with an ethylene pressure of 0.01 Reaction 12 under 0.1 MPa conditions After 24 h, the macromolecular initiator HBPE@Br containing terminal bromine was obtained after separation and purification. (2) Under nitrogen protection, using HBPE@Br obtained in step (1) as the initiator, furfuryl methacrylate and styrene as comonomers, pentamethyldiethylenetriamine as the ligand, and CuBr as the catalyst, the reaction was carried out in anhydrous toluene at 80-100 °C for 5 minutes. After 12 hours of polymerization, the long-chain star-shaped hyperbranched terpolymer HBPE@P(SrF) was obtained by separation and purification.

3. The preparation method according to claim 2, characterized in that: In step (1), the initial concentration of ethyl 2-(2-bromoisobutyryloxy)acrylate in the polymerization system is 0.1%. 1.0 mol / L; the mass amount of the Pd-diimine catalyst is 3-34% of the mass amount of 2-(2-bromoisobutyryloxy)ethyl acrylate.

4. The preparation method according to claim 2, characterized in that: In step (1), the reaction temperature is 20-30℃, the ethylene pressure is 0.1MPa, and the reaction time is 20-24h.

5. The preparation method according to claim 2, characterized in that: In step (2), the molar ratio of HBPE@Br, furfuryl methacrylate, styrene, pentamethyldiethylenetriamine, and CuBr is 1:

5. 80:50 500:0.1 100:0.01 100, where the molar amount of HBPE@Br is expressed as the molar amount of Br contained therein.

6. The preparation method according to claim 5, characterized in that: In step (2), the molar ratio of HBPE@Br, furfuryl methacrylate, styrene, pentamethyldiethylenetriamine, and CuBr is 1:

5. 15:150 250:1 5:0.5 2.

7. An HBPE@P(SrF)-based thermoplastic elastomer, characterized in that: The HBPE@P(SrF)-based thermoplastic elastomer is obtained by crosslinking and curing the long-chain star-shaped hyperbranched terpolymer HBPE@P(SrF) as described in claim 1 and a curing agent. The curing agent is at least one of 4,4'-methylene bis(N-phenylmaleimide), bismaleimide, and succinimide 6-(maleimino)hexanoate.

8. A method for preparing the HBPE@P(SrF)-based thermoplastic elastomer as described in claim 7, characterized in that: The preparation method includes: (a) Obtaining long-chain star-shaped hyperbranched terpolymer HBPE@P(SrF); (b) Take the long-chain star-shaped hyperbranched terpolymer HBPE@P(SrF) and the curing agent and dissolve them in an organic solvent to obtain a pre-cured solution; the curing agent is at least one of 4,4'-methylene bis(N-phenylmaleimide), bismaleimide, and 6-(maleimino)hexanoic acid succinimide ester. (c) Allow the pre-curing solution prepared in step (1) to cure at 25°C. Cross-linking and curing were carried out at 80℃ for 3 days. After 5 days, DA-crosslinked HBPE@P(SrF)-based thermoplastic elastomers were obtained.

9. The preparation method according to claim 8, characterized in that: In step (b), the organic solvent is selected from one of the following chemically pure or analytically pure solvents: dichloromethane, chloroform, toluene, xylene, or o-dichlorobenzene.

10. The preparation method according to claim 8, characterized in that: In step (b), the concentration of the long-chain star-shaped hyperbranched terpolymer HBPE@P(SrF) in the pre-curing solution is 50%. 500 mg / mL; the curing agent is added at a rate of 0.5% of the mass of the long-chain star-shaped hyperbranched terpolymer HBPE@P(SrF). 3%, which is 1% 2%.

11. The preparation method according to claim 10, characterized in that: In step (b), the mass of the curing agent is 1% of the mass of the long-chain star-shaped hyperbranched terpolymer HBPE@P(SrF). 2%.

12. The preparation method according to claim 8, characterized in that: In step (c), the cross-linking curing temperature is 30℃ and the cross-linking curing time is 5 days.

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