High-strength high-thermoplastic temperature polysiloxane polyurea thermoplastic elastomer containing a dynamic acetal amine bond and a method for preparing the same

Abstract

The application provides a high-strength high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing a dynamic acetal amine bond and a preparation method thereof. The application uses diisocyanate and macromolecular polydimethylsiloxane copolymer as a soft segment, diisocyanate and 1,3-bis(3-aminopropyl)tetramethyldisiloxane copolymer as a hard segment, and a polyhydroxy compound containing a dynamic acetal amine bond as a crosslinking agent, so that the prepared elastomer has good mechanical properties and a high thermoplastic temperature and can be repeatedly processed; the preparation process is simple and feasible, the product has stable performance and good reproducibility, and is suitable for popularization and application.

Description

Technical Field

[0001] This invention relates to a high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer containing dynamic acetal-amine bonds and its preparation method, belonging to the field of polymer material synthesis technology. Background Technology

[0002] Organosilicon materials are an important component of materials chemistry, with mature commercial products offering wide applications. They have attracted considerable attention due to their excellent properties, including resistance to high and low temperatures, low surface energy, high permeability, environmental resistance, biocompatibility, sterilization resistance, biodurability, and blood compatibility. Polydimethylsiloxane (PDMS) is a typical representative of the basic polymers of organosilicon materials. It is a precursor to covalently cross-linked elastomers, exhibiting flexibility, stretchability, and virtually no creep. However, the relatively poor mechanical properties, low impact strength, and low adhesion of current organosilicon materials limit their use in many fields. Traditional chemically cross-linked polysiloxane materials lack thermoforming and reprocessing capabilities, further restricting their applications.

[0003] Polyurea is a general term for a class of copolymers synthesized by the reaction of diisocyanate and diamine. Polyurea materials possess properties such as high tensile strength, high tear strength, and high tensile strength. Due to their excellent physicochemical properties and the development of their application fields, polyurea materials have attracted great interest. By using polydimethylsiloxane (PDMS) as a soft segment to react with isocyanate, polysiloxane-polyurea (PDMS-PU) materials with multiple hydrogen bonds between urea groups in the structure can be obtained. PDMS-PU not only retains the excellent properties of PDMS and improves its mechanical properties, but also lays the foundation for its recyclability. However, due to the significant difference in solubility parameters between non-polar polysiloxanes and highly polar diisocyanate compounds, macroscopic phase separation easily occurs during their reaction. This not only results in generally low molecular weight products but also leads to generally low mechanical strength in pure polysiloxane-polyurea elastomers. To reduce the macroscopic phase separation problem caused by the difference in solubility parameters in polysiloxane-polyurea, the commonly used method is to introduce transition segments such as polyethers and polyesters between the polysiloxane segments and the polyurea segments. Polyurea elastomers with mixed soft segments exhibit good mechanical strength; however, in most of these mixed soft segments, the content of transitional soft segments such as polyether and polyester dominates, while the content of polysiloxane is extremely low, thus failing to fully demonstrate the performance advantages of polysiloxane. The literature "Polym. Chem., 2018, 9, 869" introduces a novel synthetic strategy to prepare polyurea-polysiloxane-polyether type thermoplastic elastomers. Block-type soft segments were synthesized through the addition reaction of propyleneoxymethyl-terminated polydimethylsiloxane and amine-terminated polyoxypropylene. The hard segments were formed by bis(4-cyclohexyl isocyanate)methane and 2-methyl-1,5-diaminopentane chain extenders. The introduction of polyether segments avoids rapid microphase separation in the polyurea-polysiloxane copolymer, resulting in thermoplastic elastomers with good mechanical properties, but their tensile strength is less than 17 MPa at most, and the performance advantages of polysiloxane are not fully realized.

[0004] Most reports on polysiloxane-polyurea elastomers focus on their self-healing properties, but their mechanical strength is limited, resulting in limited practicality. The literature "Adv. Mater. 2018, 30, 1706846" describes a molecular design method for supramolecular polysiloxane-polyurea with high toughness, high tensile strength, and high self-healing properties. A series of polymers were synthesized through a one-pot polycondensation reaction of diamine-terminated polydimethylsiloxane with a mixture of 4,4′-methylenebis(phenylisocyanate) and isophorone diisocyanate. PDMS oligomers were linked through 4,4′-methylenebis(phenylurea) (MPU units) and isophorone diurea units (IU units), resulting in materials with excellent self-healing and tensile properties. However, the tensile strength of the elastomer materials reported in this study does not exceed 2 MPa. Chinese patent document CN116063840A discloses a carbon-based polysiloxane-polyurea elastomer material polymerized in an organic solvent from bis(3-aminopropyl)-terminated polydimethylsiloxane, diisocyanate, and single or mixed carbon materials containing hydroxyl, carboxyl functional groups, and sp2 hybrid carbon as fillers. This material exhibits excellent stretchability, thermal stability, and triboelectric properties, but its tensile strength is below 1 MPa. CN108610466A discloses a polyurea elastomer in which polysiloxane completely replaces polyether, and its preparation method. However, its maximum tensile strength and elongation at break are still not ideal, especially the elongation at break is low, and the thermoplasticity of the material has not been investigated.

[0005] Given the specific requirements of some high-temperature applications, there is a need to develop polysiloxane-polyurea thermoplastic elastomers that simultaneously possess excellent mechanical properties, high operating temperatures, and reprocessability. This requires the material to maintain good dimensional stability at high operating temperatures, i.e., to have a high plasticizing temperature. Currently, there is no method to produce a pure polysiloxane-polyurea thermoplastic elastomer that simultaneously possesses good mechanical properties and a high thermoplasticizing temperature. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a high-strength, high-thermoplasticity polysiloxane-polyurea thermoplastic elastomer containing dynamic acetal-amine bonds and its preparation method. This invention uses diisocyanate and macromolecular polydimethylsiloxane copolymer as soft segments, diisocyanate and 1,3-bis(3-aminopropyl)tetramethyldisiloxane copolymer as hard segments, and a polyhydroxy compound containing dynamic acetal-amine bonds as a crosslinking agent. The prepared elastomer exhibits excellent mechanical properties and a high thermoplasticity temperature, and can be repeatedly processed. The preparation process is simple and feasible, the product performance is stable, and the reproducibility is excellent, making it suitable for widespread application.

[0007] The technical solution of the present invention is as follows:

[0008] A method for preparing a high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer containing dynamic acetal-amine bonds includes the following steps:

[0009] (1) In anhydrous ethanol, terephthalaldehyde and N,N'-bis(2-hydroxyethyl)ethylenediamine are reacted to obtain a polyhydroxy compound containing a diacetal amine bond;

[0010] (2) In solvent A, diisocyanate a and aminopropyl-terminated polydimethylsiloxane are reacted to obtain a solution of isocyanate-terminated prepolymer X; in solvent B, 1,3-bis(3-aminopropyl)tetramethyldisiloxane and diisocyanate b are reacted to obtain a solution of aminopropyl-terminated prepolymer Y; the solution of isocyanate-terminated prepolymer X is mixed with the solution of aminopropyl-terminated prepolymer Y and reacted to obtain a solution of polysiloxane-polyurea polymer Z;

[0011] (3) Mix a solution of a polyhydroxy compound containing diacetal amine bonds and a polysiloxane polyurea polymer Z, react and dry to obtain a high-strength, high-thermoplastic temperature polysiloxane polyurea thermoplastic elastomer containing dynamic acetal amine bonds.

[0012] According to a preferred embodiment of the present invention, in step (1), the molar ratio of terephthalaldehyde to N,N'-bis(2-hydroxyethyl)ethylenediamine is 1:(2-2.3); the mass ratio of terephthalaldehyde to the volume ratio of anhydrous ethanol is 1g:5-100ml.

[0013] According to a preferred embodiment of the present invention, in step (1), anhydrous magnesium sulfate is also added during the reaction of terephthalaldehyde and N,N'-bis(2-hydroxyethyl)ethylenediamine to fully remove the water generated in the reaction.

[0014] According to a preferred embodiment of the present invention, in step (1), the reaction temperature is 55-65°C, the reaction time is 30-40 h, and the reaction is carried out under stirring conditions.

[0015] According to a preferred embodiment of the present invention, in step (1), the post-treatment method of the reaction solution obtained from the reaction is as follows: the reaction solution is filtered, and the resulting precipitate is recrystallized from ethyl acetate to obtain a polyhydroxy compound containing a diacetal-amine bond.

[0016] According to a preferred embodiment of the present invention, in step (1), the polyhydroxy compound containing a diacetal-amine bond has the structure shown in formula (I):

[0017]

[0018] According to a preferred embodiment of the present invention, in step (2), solvent A is selected from toluene, tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, methyl isobutyl ketone, γ-butyrolactone, dimethyl sulfoxide, acetonitrile, dioxane, xylene, isopropanol, dichloromethane, acetone, ethyl acetate, or n-hexane. The total mass ratio of diisocyanate a and aminopropyl-terminated polydimethylsiloxane to the volume ratio of solvent A is 1 g: 0.5–28 ml, preferably 1 g: 0.5–18 ml.

[0019] According to a preferred embodiment of the present invention, in step (2), diisocyanate a is one or a combination of two or more of toluene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, hexamethylene diisocyanate, methylcyclohexyl diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, terephthalic diisocyanate, terephthalic diisocyanate or tetramethylphenyl diisocyanate.

[0020] According to a preferred embodiment of the present invention, in step (2), the molar ratio of diisocyanate a to aminopropyl-terminated polydimethylsiloxane is (1-2):1.

[0021] According to a preferred embodiment of the present invention, in step (2), the weight-average molecular weight of the aminopropyl-terminated polydimethylsiloxane is 500-20000 g / mol, preferably 1000-5000 g / mol.

[0022] According to the present invention, in step (2), the aminopropyl-terminated polydimethylsiloxane has the structure shown in formula (II):

[0023]

[0024] According to a preferred embodiment of the present invention, in step (2), the aminopropyl-terminated polydimethylsiloxane is added dropwise to the reaction system in the form of an aminopropyl-terminated polydimethylsiloxane solution under stirring and protective gas protection; the type of solvent used for the aminopropyl-terminated polydimethylsiloxane solution is the same as that of solvent A, and the concentration of the aminopropyl-terminated polydimethylsiloxane solution is 0.1-0.5 g / mL; the protective gas is nitrogen or argon.

[0025] According to a preferred embodiment of the present invention, in step (2), the reaction temperature of diisocyanate a and aminopropyl-terminated polydimethylsiloxane is -10 to 30°C, preferably -10 to 20°C, and the reaction time is 30 to 480 min, preferably 30 to 300 min. The reaction is carried out under stirring conditions and protective gas protection. Preferably, the protective gas is nitrogen or argon.

[0026] According to a preferred embodiment of the present invention, in step (2), the method for preparing the solution of the isocyanate-terminated prepolymer X includes the following steps: mixing diisocyanate a and solvent A1, and adding dropwise a mixture of aminopropyl-terminated polydimethylsiloxane and solvent A2 under stirring conditions and protective gas protection, and reacting to obtain a solution of isocyanate-terminated prepolymer X; preferably, the types of solvent A1 and solvent A2 are the same as those of solvent A, and the total volume of solvent A1 and solvent A2 is the same as that of solvent A.

[0027] According to the present invention, in step (2), the isocyanate-terminated prepolymer X has the structure shown in formula (Ⅲ):

[0028]

[0029]

[0030] According to a preferred embodiment of the present invention, in step (2), solvent B is selected from toluene, tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, methyl isobutyl ketone, γ-butyrolactone, dimethyl sulfoxide, acetonitrile, dioxane, xylene, isopropanol, dichloromethane, acetone, ethyl acetate, or n-hexane. The total mass ratio of 1,3-bis(3-aminopropyl)tetramethyldisiloxane and diisocyanate b to the volume ratio of solvent B is 1 g: 2 to 15 ml, preferably 1 g: 2 to 10 ml.

[0031] According to a preferred embodiment of the present invention, in step (2), diisocyanate b is one or a combination of two or more of hexamethylene diisocyanate, isophorone diisocyanate (IPDI), diphenylmethane-4,4'-diisocyanate (MDI), phenylmethylene diisocyanate, toluene diisocyanate (TDI), tetramethylphenylmethylene diisocyanate, dicyclohexylmethane diisocyanate or methylcyclohexyl diisocyanate.

[0032] According to a preferred embodiment of the present invention, in step (2), the molar ratio of diisocyanate b to 1,3-bis(3-aminopropyl)tetramethyldisiloxane is (0.5-1):1.

[0033] According to a preferred embodiment of the present invention, in step (2), diisocyanate b is added dropwise to the reaction system in the form of a diisocyanate b solution under stirring conditions and protective gas protection; the type of solvent used for the diisocyanate b solution is the same as that of solvent B, and the concentration of the diisocyanate b solution is 1-2 g / mL; the protective gas is nitrogen or argon.

[0034] According to a preferred embodiment of the present invention, in step (2), the reaction temperature of 1,3-bis(3-aminopropyl)tetramethyldisiloxane and diisocyanate b is -10 to 30°C, preferably -10 to 10°C, and the reaction time is 1 to 2 min. The reaction is carried out under stirring conditions and protective gas protection. Preferably, the protective gas is nitrogen or argon.

[0035] According to a preferred embodiment of the present invention, in step (2), the method for preparing the solution of aminopropyl-terminated prepolymer Y includes the following steps: mixing 1,3-bis(3-aminopropyl)tetramethyldisiloxane and solvent B1, and adding a mixture of diisocyanate b and solvent B2 dropwise under stirring conditions and protective gas protection, and reacting to obtain a solution of aminopropyl-terminated prepolymer Y; preferably, the types of solvent B1 and solvent B2 are the same as those of solvent B, and the total volume of solvent B1 and solvent B2 is the same as that of solvent B.

[0036] According to a preferred embodiment of the present invention, in step (2), the aminopropyl-terminated prepolymer Y has the structure shown in formula (Ⅳ):

[0037]

[0038] According to a preferred embodiment of the present invention, in step (2), the molar ratio of diisocyanate a to 1,3-bis(3-aminopropyl)tetramethyldisiloxane is 1:1.

[0039] According to a preferred embodiment of the present invention, in step (2), the solution of the aminopropyl-terminated prepolymer Y is added dropwise to the solution of the isocyanate-terminated prepolymer X under a protective gas atmosphere and stirring conditions. Preferably, the protective gas is nitrogen or argon.

[0040] According to a preferred embodiment of the present invention, in step (2), the reaction temperature after mixing the solution of isocyanate-terminated prepolymer X with the solution of aminopropyl-terminated prepolymer Y is 20-75°C, the reaction time is 60-300 min, and the reaction is carried out under stirring conditions.

[0041] According to the present invention, in step (2), the polysiloxane polyurea polymer Z has the structure shown in formula (V):

[0042]

[0043] According to a preferred embodiment of the present invention, in step (3), the mass ratio of the polyhydroxy compound containing the diacetal amine bond to the diisocyanate a in step (2) is 1:3-12, preferably 1:5-11.3.

[0044] According to a preferred embodiment of the present invention, in step (3), the reaction temperature is 20-75°C, the reaction time is 60-300 min, and the reaction is carried out under stirring conditions.

[0045] According to a preferred embodiment of the present invention, in step (3), the drying method is as follows: stand at room temperature for 8-18 hours, and then vacuum dry at 60-80°C for 20-30 hours.

[0046] A high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer containing dynamic acetal-amine bonds is prepared by the above method.

[0047] The technical features and beneficial effects of this invention are as follows:

[0048] 1. This invention uses a copolymer of diisocyanate and macromolecular aminopropyl-terminated polydimethylsiloxane as the soft segment and a copolymer of diisocyanate and 1,3-bis(3-aminopropyl)tetramethyldisiloxane as the hard segment to prepare a polysiloxane polyurea elastomer. The similarity in structure between the soft and hard segments increases the compatibility between the two phases, greatly improves the reaction efficiency, avoids macroscopic phase separation, and improves the elongation at break of the polysiloxane polyurea elastomer with a high hard segment content. The resulting elastomer has high mechanical strength and can fully reflect the performance advantages of polysiloxane.

[0049] 2. Using polyhydroxy compounds containing dynamic acetal-amine bonds as crosslinking agents, a dynamically covalently crosslinked network that can dissociate at high temperatures is introduced into polysiloxane-polyurea elastomers to obtain thermoplastic elastomers. This further enhances the mechanical properties of the elastomers, while also giving them a high thermoplasticization temperature, high operating temperature, good dimensional stability at higher operating temperatures, and the ability to be repeatedly processed. The aforementioned acetal-amine bond is a dynamic covalent bond. Elastomers prepared using compounds containing this dynamic bond as crosslinking agents maintain the same dissociation and association rates over a wide temperature range. The system contains a constant number of acetal-amine crosslinking points, and the crosslinked structure remains stable. When the temperature rises above the thermoplasticization temperature, the dissociation rate exceeds the association rate, the network crosslinking density decreases, and the elastomer can be reshaped.

[0050] 3. The preparation process of this invention is simple and feasible, the product performance is stable and reproducible, and it is suitable for widespread application. Attached Figure Description

[0051] Figure 1 The nuclear magnetic resonance H-spectrum of compound C obtained in Example 1 of this invention;

[0052] Figure 2 The infrared spectrum of the elastomer obtained in Example 1 of this invention;

[0053] Figure 3 This is a thermoplastic temperature test diagram of the elastomer prepared in Example 1 of the present invention. Detailed Implementation

[0054] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0055] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the experimental materials used in the following embodiments are all available through conventional commercial channels.

[0056] Test instructions:

[0057] Nuclear magnetic resonance (NMR) spectroscopy was performed using an AVAVCE (Bruker) 400MHz NMR spectrometer with deuterated chloroform (CDCl3) as the solvent at room temperature.

[0058] Infrared spectroscopy was performed using a Bruker Tensor 27 infrared spectrometer. Samples were compressed using potassium bromide pellets, and 16 samples were collected, with the frequency range from 4000 cm⁻¹. -1 up to 400cm -1 The resolution is 4cm. -1 .

[0059] The mechanical properties of the samples were tested using an Instron 3343 materials testing system. According to GB / T 1040-2006, the solid samples were hot-pressed at 180℃ and 15MPa for 15 minutes to obtain thin sheet samples, which were then cut into dumbbell-shaped strips. The mechanical properties of the materials were determined by stress-strain analysis, and at least three parallel tests were conducted.

[0060] The thermoplastic temperature of the samples was tested using static thermomechanical analysis (TMA) with a Netzsch TMA4000 instrument. The samples were cut into strips (20×10×0.5mm), a stress of 1N was applied, and the test temperature was 35℃~160℃ with a heating rate of 3℃ / min.

[0061] All tests were conducted at room temperature, normal pressure, and 50% relative humidity, unless otherwise stated.

[0062] Example 1

[0063] A method for preparing a high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer containing dynamic acetal-amine bonds includes the following steps:

[0064] Step 1: In a solution of terephthalaldehyde (13.4 g, 0.1 mol) in anhydrous ethanol (100 mL), N,N'-bis(2-hydroxyethyl)ethylenediamine (32.6 g, 0.22 mol) and excess anhydrous magnesium sulfate were added (to completely remove the water generated in the reaction). The resulting suspension was stirred at 60 °C for 36 h, and then filtered. The resulting precipitate was purified by recrystallization from ethyl acetate to obtain a yellow crystalline polyhydroxy compound containing diacetal-amine bonds, denoted as C.

[0065] Step 2: At 0°C, add 1311.75 mg (0.005 mol) of HMDI (dicyclohexylmethane diisocyanate) and 10 mL of tetrahydrofuran to a flask equipped with a nitrogen delivery tube, a constant pressure dropping funnel, a condenser, and a stirring device. Purge with nitrogen and stir rapidly. Add a tetrahydrofuran solution of bis(3-aminopropyl)-terminated polydimethylsiloxane (3000 mg of bis(3-aminopropyl)-terminated polydimethylsiloxane and 15 mL of tetrahydrofuran) dropwise through the dropping funnel. After the addition is complete, continue stirring at 0°C for 5 h to obtain a solution of isocyanate-terminated prepolymer X.

[0066] Step 3: At 0°C, add 1242.55 mg (0.005 mol) of 1,3-bis(3-aminopropyl)tetramethyldisiloxane and 5 ml of isopropanol to a flask equipped with a nitrogen delivery tube, a constant pressure dropping funnel, a condenser, and a stirring device. Purge with nitrogen and stir rapidly. Add a mixed solution of 784.05 mg (0.003 mol) of HMDI (dicyclohexylmethane diisocyanate) and 5 ml of isopropanol dropwise through the dropping funnel. After the rapid addition is completed, continue stirring at 0°C for 2 min to obtain a solution of aminopropyl-terminated prepolymer Y.

[0067] Step 4: Transfer the solution of aminopropyl-terminated prepolymer Y obtained in Step 3 to a dropping funnel, purge with nitrogen, stir rapidly, and add dropwise to the solution of isocyanate-terminated prepolymer X obtained in Step 2. After the addition is complete, stir and react at 45°C for 5 hours to obtain a solution of polysiloxane polyurea polymer Z.

[0068] Step 5: Add 260 mg of compound C to the solution of polysiloxane-polyurea polymer Z, and continue stirring at 45°C for 1 hour before stopping the reaction. Transfer the product to a polytetrafluoroethylene mold, dry at room temperature for 12 hours, and then dry in a vacuum oven at 80°C for 24 hours to obtain a high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer containing dynamic acetal-amine bonds.

[0069] The nuclear magnetic resonance (NMR) spectrum of compound C obtained in this embodiment is as follows: Figure 1 As shown, the target product was successfully prepared.

[0070] The FTIR spectrum of the high-strength, high-thermoplastic temperature polysiloxane-polyurea thermoplastic elastomer containing dynamic acetall bonds obtained in this embodiment is as follows: Figure 2 As shown, at 2270cm -1 The disappearance of the stretching vibration peak of N=C=O indicates that the NCO reaction is complete; 3300cm -1 The nearby absorption peak is the stretching vibration peak of the urea group NH, at 1700 cm⁻¹. -1 The absorption peak at that position is the stretching vibration peak of the carbonyl C=O group. The FTIR spectrum confirms the successful preparation of the target product.

[0071] The high-strength, high-thermoplastic temperature polysiloxane-polyurea thermoplastic elastomer with dynamic acetal-amine bonds obtained in this embodiment has a tensile strength of 27 MPa and an elongation at break of 193%.

[0072] The thermoplastic temperature of the high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer containing dynamic acetall bonds obtained in this embodiment is as follows: Figure 3 Its temperature is 126℃, which is a relatively high thermoplastic temperature.

[0073] Example 2

[0074] A method for preparing a high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer containing dynamic acetal-amine bonds includes the following steps:

[0075] Step 1 is the same as step 1 in Example 1.

[0076] Step 2: At 0°C, add 1112 mg (0.005 mol) of IPDI (isophorone diisocyanate) and 10 mL of isopropanol to a flask equipped with a nitrogen delivery tube, a constant pressure dropping funnel, a condenser, and a stirring device. Purge with nitrogen and stir rapidly. Add dropwise a solution of bis(3-aminopropyl)-terminated polydimethylsiloxane in isopropanol (wherein, the content of bis(3-aminopropyl)-terminated polydimethylsiloxane is 3003 mg and the volume of isopropanol is 10 mL) through the dropping funnel. After the addition is completed, continue stirring at 0°C for 4 h to obtain a solution of isocyanate-terminated prepolymer X.

[0077] Step 3: At -10℃, add 1242.55 mg (0.005 mol) of 1,3-bis(3-aminopropyl)tetramethyldisiloxane and 10 ml of dichloromethane to a flask equipped with a nitrogen delivery tube, a constant pressure dropping funnel, a condenser, and a stirring device. Purge with nitrogen and stir rapidly. Add a mixture of 750.85 mg (0.003 mol) of MDI and 5 ml of dichloromethane dropwise through the dropping funnel. After the addition is complete, continue stirring at -10℃ for 2 min to obtain a solution of aminopropyl-terminated prepolymer Y.

[0078] Step 4: Transfer the solution of aminopropyl-terminated prepolymer Y obtained in Step 3 to a dropping funnel, purge with nitrogen, stir rapidly, and add dropwise to the solution of isocyanate-terminated prepolymer X obtained in Step 2. After the addition is complete, stir and react at 50°C for 5 hours to obtain a solution of polysiloxane polyurea polymer Z.

[0079] Step 5: Add 123 mg of compound C to the solution of polysiloxane-polyurea polymer Z, and continue stirring at 50°C for 3 hours before stopping the reaction. Transfer the product to a polytetrafluoroethylene mold, dry at room temperature for 12 hours, and then dry in a vacuum oven at 80°C for 24 hours to obtain a high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer containing dynamic acetal-amine bonds.

[0080] The high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer with dynamic acetal-amine bonds obtained in this embodiment has a tensile strength of 16.32 MPa and an elongation at break of 287%.

[0081] The high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer with dynamic acetal-amine bonds obtained in this embodiment has a thermoplastic temperature of 115°C.

[0082] Example 3

[0083] A method for preparing a high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer containing dynamic acetal-amine bonds includes the following steps:

[0084] Step 1 is the same as step 1 in Example 1.

[0085] Step 2: At -10℃, add 1312 mg (0.005 mol) of HMDI (dicyclohexylmethane diisocyanate) and 5 ml of toluene to a flask equipped with a nitrogen delivery tube, a constant pressure dropping funnel, a condenser, and a stirring device. Purge with nitrogen and stir rapidly. Add dropwise a toluene solution of bis(3-aminopropyl)-terminated polydimethylsiloxane (4000 mg of bis(3-aminopropyl)-terminated polydimethylsiloxane and 15 mL of toluene) through the dropping funnel. After the addition is complete, continue stirring at -10℃ for 4 h to obtain a solution of isocyanate-terminated prepolymer X.

[0086] Step 3: At -10℃, add 1242.88 mg (0.005 mol) of 1,3-bis(3-aminopropyl)tetramethyldisiloxane and 5 ml of dichloromethane to a flask equipped with a nitrogen delivery tube, a constant pressure dropping funnel, a condenser, and a stirring device. Purge with nitrogen and stir rapidly. Add a mixed solution of 1050 mg (0.004 mol) of HMDI and 5 ml of dichloromethane dropwise through the dropping funnel. After the addition is complete, continue stirring at -10℃ for 2 min to obtain a solution of aminopropyl-terminated prepolymer Y.

[0087] Step 4: Transfer the solution of aminopropyl-terminated prepolymer Y obtained in Step 3 to a dropping funnel, purge with nitrogen, stir rapidly, and add dropwise to the solution of isocyanate-terminated prepolymer X obtained in Step 2. After the addition is complete, stir and react at 30°C for 4 hours to obtain a solution of polysiloxane polyurea polymer Z.

[0088] Step 5: Add 116 mg of compound C to the solution of polysiloxane-polyurea polymer Z, and continue stirring at 30°C for 1 hour before stopping the reaction. Transfer the product to a polytetrafluoroethylene mold, dry at room temperature for 12 hours, and then dry in a vacuum oven at 80°C for 24 hours to obtain a high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer containing dynamic acetal-amine bonds.

[0089] The high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer with dynamic acetal-amine bonds obtained in this embodiment has a tensile strength of 28.32 MPa and an elongation at break of 125.7%.

[0090] The high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer with dynamic acetal-amine bonds obtained in this embodiment has a thermoplastic temperature of 135°C.

[0091] Example 4

[0092] A method for preparing a high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer containing dynamic acetal-amine bonds includes the following steps:

[0093] Step 1 is the same as step 1 in Example 1.

[0094] Step 2: At -10℃, add 1311.5 mg (0.005 mol) of HMDI and 5 ml of toluene to a flask equipped with a nitrogen delivery tube, a constant pressure dropping funnel, a condenser, and a stirring device. Purge with nitrogen and stir rapidly. Add a toluene solution of bis(3-aminopropyl)-terminated polydimethylsiloxane (Mw = 5000 g / mol, where the content of bis(3-aminopropyl)-terminated polydimethylsiloxane is 20 g and the volume of toluene is 100 mL) dropwise through the dropping funnel. After the addition is completed, continue stirring at -10℃ for 4 h to obtain a solution of isocyanate-terminated prepolymer X.

[0095] Step 3: At -10℃, add 1243 mg (0.005 mol) of 1,3-bis(3-aminopropyl)tetramethyldisiloxane and 10 ml of n-hexane to a flask equipped with a nitrogen delivery tube, a constant pressure dropping funnel, a condenser, and a stirring device. Purge with nitrogen and stir rapidly. Add a mixed solution of 1053 mg (0.004 mol) of HMDI and 10 ml of n-hexane dropwise through the dropping funnel. After the addition is complete, continue stirring at -10℃ for 2 min to obtain a solution of aminopropyl-terminated prepolymer Y.

[0096] Step 4: Transfer the solution of aminopropyl-terminated prepolymer Y obtained in Step 3 to a dropping funnel, purge with nitrogen, stir rapidly, and add dropwise to the solution of isocyanate-terminated prepolymer X obtained in Step 2. After the addition is complete, stir and react at 50°C for 4 hours to obtain a solution of polysiloxane polyurea polymer Z.

[0097] Step 5: Add 150 mg of compound C to the solution of polysiloxane-polyurea polymer Z, and continue stirring at 50°C for 5 hours before stopping the reaction. Transfer the product to a polytetrafluoroethylene mold, dry at room temperature for 12 hours, and then dry in a vacuum oven at 80°C for 24 hours to obtain a high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer containing dynamic acetal-amine bonds.

[0098] The high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer with dynamic acetal-amine bonds obtained in this embodiment has a tensile strength of 7.52 MPa and an elongation at break of 186.9%.

[0099] The high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer with dynamic acetal-amine bonds obtained in this embodiment has a thermoplastic temperature of 110°C.

[0100] Comparative Example 1

[0101] A method for preparing an elastomer, as described in Example 1, except that no polyhydroxy compound is added; the specific method is as follows:

[0102] Steps 1-2 in this comparative example are the same as steps 2-3 in Example 1;

[0103] Step 3: Transfer the solution of aminopropyl-terminated prepolymer Y obtained in Step 2 to a dropping funnel, purge with nitrogen, stir rapidly, and add dropwise to the solution of isocyanate-terminated prepolymer X obtained in Step 2. After the addition is complete, stir the reaction at 45°C for 6 hours. Transfer the product to a polytetrafluoroethylene mold, dry at room temperature for 12 hours, and then dry in an 80°C vacuum oven for 24 hours to obtain the elastomer.

[0104] The tensile strength of the elastomer obtained in this comparative example is 22.12 MPa, and the elongation at break is 157%.

[0105] The thermoplastic temperature of the elastomer obtained in this comparative example is 116℃.

[0106] The difference between this comparative example and Example 1 is that no polyhydroxy compound C containing dynamic covalent acetal amine bonds was added, and no dynamic covalent cross-linked network structure was formed. Therefore, the mechanical properties and thermoplastic temperature of the material are significantly reduced.

[0107] Comparative Example 2

[0108] A method for preparing an elastomer, as described in Example 3, except that in step 5, the amount of compound C used is 50 mg; the other steps and conditions are the same as in Example 1.

[0109] The tensile strength of the elastomer obtained in this comparative example is 27 MPa, and the elongation at break is 118%.

[0110] The thermoplastic temperature of the elastomer obtained in this comparative example is 125℃.

[0111] The difference between this comparative example and Example 3 is that the amount of compound C was reduced in step 5, resulting in a decrease in the degree of dynamic crosslinking. Although the loss of mechanical properties of the material was not significant, the thermoplastic temperature was significantly reduced.

Claims

1. A method for preparing a high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer containing dynamic acetal-amine bonds, comprising the following steps: (1) In anhydrous ethanol, terephthalaldehyde and N,N'-bis(2-hydroxyethyl)ethylenediamine are reacted to give a polyhydroxy compound containing a diacetal-amine bond; (2) In solvent A, diisocyanate a and aminopropyl-terminated polydimethylsiloxane are reacted to obtain a solution of isocyanate-terminated prepolymer X; in solvent B, 1,3-bis(3-aminopropyl)tetramethyldisiloxane and diisocyanate b are reacted to obtain a solution of aminopropyl-terminated prepolymer Y; the solution of isocyanate-terminated prepolymer X is mixed with the solution of aminopropyl-terminated prepolymer Y and reacted to obtain a solution of polysiloxane-polyurea polymer Z; (3) Mix the solution of the polyhydroxy compound containing diacetal amine bonds and the polysiloxane polyurea polymer Z, react and dry to obtain a high-strength, high-thermoplastic temperature polysiloxane polyurea thermoplastic elastomer containing dynamic acetal amine bonds; the mass ratio of the polyhydroxy compound containing diacetal amine bonds and the diisocyanate a in step (2) is 1:3-12.

2. The method for preparing the high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer containing dynamic acetal-amine bonds according to claim 1, characterized in that, Step (1) includes one or more of the following conditions: i. The molar ratio of terephthalaldehyde to N,N'-bis(2-hydroxyethyl)ethylenediamine is 1:(2~2.3); the mass ratio of terephthalaldehyde to anhydrous ethanol is 1g:5~100ml; ii. Anhydrous magnesium sulfate is also added during the reaction of terephthalaldehyde and N,N'-bis(2-hydroxyethyl)ethylenediamine to fully remove the water generated in the reaction; iii. The reaction temperature is 55-65℃, the reaction time is 30-40h, and the reaction is carried out under stirring conditions.

3. The method for preparing the high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer containing dynamic acetal-amine bonds according to claim 1, characterized in that, Step (2) includes one or more of the following conditions: i. Solvent A is selected from one of toluene, tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, methyl isobutyl ketone, γ-butyrolactone, dimethyl sulfoxide, acetonitrile, dioxane, xylene, isopropanol, dichloromethane, acetone, ethyl acetate, or n-hexane; the total mass ratio of diisocyanate a and aminopropyl-terminated polydimethylsiloxane to the volume ratio of solvent A is 1 g : 0.5~28 ml; ii. Diisocyanate a is one or a combination of two or more of toluene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, hexamethylene diisocyanate, methylcyclohexyl diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, terephthalic diisocyanate, terephthalic diisocyanate or tetramethyl terephthalic diisocyanate; iii. The molar ratio of diisocyanate a to aminopropyl-terminated polydimethylsiloxane is (1~2):1; iv. The weight-average molecular weight of aminopropyl-terminated polydimethylsiloxane is 500-20000 g / mol; v. The aminopropyl-terminated polydimethylsiloxane is added dropwise to the reaction system in the form of an aminopropyl-terminated polydimethylsiloxane solution under stirring and protective gas protection. The type of solvent used for the aminopropyl-terminated polydimethylsiloxane solution is the same as that used for solvent A, and the concentration of the aminopropyl-terminated polydimethylsiloxane solution is 0.1-0.5 g / mL. The protective gas is nitrogen or argon. The reaction temperature of vi, diisocyanate a and aminopropyl-terminated polydimethylsiloxane is -10~30℃, and the reaction time is 30~480min. The reaction is carried out under stirring and protective gas conditions; the protective gas is nitrogen or argon.

4. The method for preparing the high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer containing dynamic acetal-amine bonds according to claim 3, characterized in that, Includes one or more of the following conditions: i. The total mass ratio of diisocyanate a and aminopropyl-terminated polydimethylsiloxane to solvent A is 1 g : 0.5~18 ml; ii. The weight-average molecular weight of aminopropyl-terminated polydimethylsiloxane is 1000-5000 g / mol; iii. The reaction temperature of diisocyanate a and aminopropyl-terminated polydimethylsiloxane is -10~20℃, and the reaction time is 30~300min.

5. The method for preparing the high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer containing dynamic acetal-amine bonds according to claim 1, characterized in that, In step (2), the method for preparing the solution of isocyanate-terminated prepolymer X includes the following steps: mixing diisocyanate a and solvent A1, and adding dropwise a mixture of aminopropyl-terminated polydimethylsiloxane and solvent A2 under stirring conditions and protective gas protection, and obtaining the solution of isocyanate-terminated prepolymer X by reaction; the types of solvent A1 and solvent A2 are the same as those of solvent A, and the total volume of solvent A1 and solvent A2 is the same as that of solvent A.

6. The method for preparing the high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer containing dynamic acetal-amine bonds according to claim 1, characterized in that, Step (2) includes one or more of the following conditions: i. Solvent B is selected from one of toluene, tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, methyl isobutyl ketone, γ-butyrolactone, dimethyl sulfoxide, acetonitrile, dioxane, xylene, isopropanol, dichloromethane, acetone, ethyl acetate, or n-hexane; the total mass ratio of 1,3-bis(3-aminopropyl)tetramethyldisiloxane and diisocyanate b to the volume ratio of solvent B is 1 g: 2~15 ml; ii. Diisocyanate b is one or a combination of two or more of hexamethylene diisocyanate, isophorone diisocyanate (IPDI), diphenylmethane-4,4'-diisocyanate (MDI), phenylmethylene diisocyanate, toluene diisocyanate (TDI), tetramethylphenylmethylene diisocyanate, dicyclohexylmethane diisocyanate or methylcyclohexyl diisocyanate; iii. The molar ratio of diisocyanate b to 1,3-bis(3-aminopropyl)tetramethyldisiloxane is (0.5~1):1; iv. Diisocyanate b is added dropwise to the reaction system as a diisocyanate b solution under stirring and protective gas conditions; the type of solvent used for the diisocyanate b solution is the same as that for solvent B, and the concentration of the diisocyanate b solution is 1-2 g / mL; the protective gas is nitrogen or argon. The reaction temperature of v, 1,3-bis(3-aminopropyl)tetramethyldisiloxane and diisocyanate b is -10~30℃, the reaction time is 1~2 min, and the reaction is carried out under stirring and protective gas protection; the protective gas is nitrogen or argon.

7. The method for preparing the high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer containing dynamic acetal-amine bonds according to claim 6, characterized in that, Includes one or more of the following conditions: The total mass ratio of i, 1,3-bis(3-aminopropyl)tetramethyldisiloxane and diisocyanate b to the volume ratio of solvent B is 1 g : 2~10 ml; ii. The reaction temperature of 1,3-bis(3-aminopropyl)tetramethyldisiloxane and diisocyanate b is -10~10℃.

8. The method for preparing the high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer containing dynamic acetal-amine bonds according to claim 1, characterized in that, In step (2), the preparation method of the aminopropyl-terminated prepolymer Y solution includes the following steps: mixing 1,3-bis(3-aminopropyl)tetramethyldisiloxane and solvent B1, and adding a mixture of diisocyanate b and solvent B2 dropwise under stirring conditions and protective gas protection, and obtaining the aminopropyl-terminated prepolymer Y solution by reaction; the types of solvent B1 and solvent B2 are the same as those of solvent B, and the total volume of solvent B1 and solvent B2 is the same as that of solvent B.

9. The method for preparing the high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer containing dynamic acetal-amine bonds according to claim 1, characterized in that, Step (2) includes one or more of the following conditions: The molar ratio of i, diisocyanate a, and 1,3-bis(3-aminopropyl)tetramethyldisiloxane is 1:1; ii. The solution of aminopropyl-terminated prepolymer Y is added dropwise to the solution of isocyanate-terminated prepolymer X under the protection of a protective gas and stirring; the protective gas is nitrogen or argon. iii. The reaction temperature after mixing the solution of isocyanate-terminated prepolymer X with the solution of aminopropyl-terminated prepolymer Y is 20~75℃, the reaction time is 60~300min, and the reaction is carried out under stirring conditions.

10. The method for preparing the high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer containing dynamic acetal-amine bonds according to claim 1, characterized in that, The mass ratio of the polyhydroxy compound containing a diacetal amine bond to diisocyanate a in step (2) is 1:5-11.

3.

11. The method for preparing the high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer containing dynamic acetal-amine bonds according to claim 1, characterized in that, Step (3) includes one or more of the following conditions: i. The reaction temperature is 20-75℃, the reaction time is 60-300 min, and the reaction is carried out under stirring conditions; ii. Drying method is as follows: let stand at room temperature for 8-18 hours, then vacuum dry at 60-80℃ for 20-30 hours.

12. A high-strength, high-thermoplastic-temperature polysiloxane-polyurea thermoplastic elastomer containing dynamic acetal-amine bonds, prepared by any one of claims 1-11.

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