High-strength and high-thermal-plastic-temperature polysiloxane polyurea thermoplastic elastomer containing dynamic acetal-amine bonds and preparation method of high-strength and high-thermal-plastic-temperature polysiloxane polyurea thermoplastic elastomer

Abstract

The invention provides a high-strength and high-thermal-plastic-temperature polysiloxane polyurea thermoplastic elastomer containing dynamic acetal amine bonds and a preparation method of the high-strength and high-thermal-plastic-temperature polysiloxane polyurea thermoplastic elastomer. According to the invention, the diisocyanate and macromolecular polydimethylsiloxane copolymer is used as a soft segment, the diisocyanate and 1, 3-bis (3-aminopropyl) tetramethyldisiloxane copolymer is used as a hard segment, and the polyhydroxy compound containing dynamic acetal amine bonds is used as a cross-linking agent, so that the prepared elastomer has good mechanical properties and high thermal plasticizing temperature, and can be used for preparing the polyurethane elastomer. Repeated processing can be realized; the preparation process is simple and feasible, and the product has stable performance and good reproducibility and is suitable for popularization and application.

Description

Technical Field

[0001] The invention relates to a high-strength and high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing a dynamic aminal bond and a preparation method thereof, belonging to the technical field of polymer material synthesis. Background Art

[0002] Silicone materials are an important part of materials chemistry, with mature commercial products that are widely used. Silicone materials have attracted much attention due to their excellent properties such as resistance to high and low temperatures, low surface energy, high permeability, resistance to environmental conditions, as well as biocompatibility, sterilization tolerance, biodurability and blood compatibility. Polydimethylsiloxane (PDMS) is a typical representative of the base polymer of silicone materials. It is a precursor of covalently cross-linked elastomers, soft, stretchable and almost creep-free. However, the poor mechanical properties, low impact strength and low adhesion of silicone materials currently limit their use in many fields. Traditional chemically cross-linked polysiloxane materials do not have thermal remodeling and reproducibility, so their applications are also limited.

[0003] Polyurea is a general term for a class of copolymers synthesized by the reaction of diisocyanates and diamines. Polyurea materials have the characteristics of high tensile strength, high tear strength and tensile strength. Due to its excellent physical and chemical properties and the development of its application fields, polyurea materials have aroused great interest. Using polydimethylsiloxane (PDMS) as a soft segment to react with isocyanate, polysiloxane-polyurea (PDMS-PU) materials with multiple hydrogen bonds formed between urea groups in the structure can be obtained. PDMS-PU can not only retain the excellent properties of PDMS, improve its mechanical properties, but also lay the foundation for its recycling and processing performance. However, due to the great difference in the solubility parameters of non-polar polysiloxane and highly polar diisocyanate compounds, the reaction between the two is very easy to cause macroscopic phase separation, which not only makes the product molecular weight generally low, but also leads to generally low mechanical strength of pure polysiloxane polyurea elastomers. In order to reduce the macroscopic phase separation problem caused by the difference in solubility parameters of polysiloxane polyurea, the commonly used method is to introduce transition segments such as polyether and polyester between the polysiloxane segment and the polyurea segment. This type of mixed soft segment polyurea elastomer has good mechanical strength. However, in most mixed soft segments, the content of transition soft segments such as polyether and polyester is dominant, and the content of polysiloxane is very small, so the performance advantages of polysiloxane cannot be reflected. The document "Polym.Chem., 2018, 9, 869" introduces a new synthesis strategy to prepare polyurea-polysiloxane-polyether thermoplastic elastomer. The block-type soft segment was synthesized by the addition reaction of propyleneoxymethyl-terminated polydimethylsiloxane and amine-terminated polyoxypropylene. The hard segment is formed by bis(4-isocyanatocyclohexyl)methane and 2-methyl-1,5-diaminopentane chain extender. The introduction of polyether segments avoids the sharp microphase separation in polyurea-polysiloxane copolymers, and a thermoplastic elastomer with good mechanical properties can be obtained, but its maximum tensile strength is less than 17MPa, and the performance advantages of polysiloxane are not fully reflected.

[0004] Most of the reports on polysiloxane polyurea elastomers are studies on self-healing properties, with limited mechanical strength and general practicality. The document "Adv. Mater. 2018, 30, 1706846" involves a design method for a molecule with high toughness, high stretchability, and high self-healing properties of supramolecular polysiloxane polyurea. A series of polymers were synthesized by a one-pot polycondensation reaction of a mixture of double-terminated amino-group polydimethylsiloxane and 4,4′-methylenebis(phenyl isocyanate) and isophorone diisocyanate. PDMS oligomers are connected by 4,4′-methylenebis(phenyl urea) (MPU unit) and isophorone diurea unit (IU unit) to obtain a material with good self-healing and stretchability. However, the tensile strength of the elastomeric materials reported does not exceed 2MPa. Chinese patent document CN116063840A discloses a carbon-based polysiloxane-polyurea elastomer material polymerized in an organic solvent by bis(3-aminopropyl)-terminated polydimethylsiloxane, diisocyanate and single or mixed carbon material carbon-based fillers containing hydroxyl, carboxyl functional groups and sp2 hybridized carbon. The material has excellent stretchability, thermal stability and triboelectric performance, but the tensile strength is less than 1MPa. CN108610466A discloses a polyurea elastomer completely replacing polyether with polysiloxane and a preparation method thereof, but 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 explored.

[0005] In view of the special requirements of some high-temperature application fields, it is necessary to develop polysiloxane polyurea thermoplastic elastomers with excellent mechanical properties, high use temperature, and repeatable processing. This requires that the material can maintain good dimensional stability at high working temperatures, that is, it has a high plasticizing temperature. At present, there is no method to produce pure polysiloxane polyurea thermoplastic elastomers with good mechanical properties and high thermal plasticizing temperature. Summary of the invention

[0006] In view of the deficiencies of the prior art, the present invention provides a high-strength and high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing dynamic aminal bonds and a preparation method thereof. The present invention adopts a diisocyanate and a macromolecular polydimethylsiloxane copolymer as a soft segment, a diisocyanate and a 1,3-bis(3-aminopropyl)tetramethyldisiloxane copolymer as a hard segment, and a polyhydroxy compound containing a dynamic aminal bond as a crosslinking agent. The prepared elastomer has good mechanical properties and a high thermoplastic temperature, and can be processed repeatedly; the preparation process is simple and feasible, the product performance is stable, the reproducibility is good, and it is suitable for popularization and application.

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

[0008] A method for preparing a high-strength and high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing dynamic aminal bonds, comprising the steps of:

[0009] (1) In anhydrous ethanol, terephthalaldehyde and N,N'-bis(2-hydroxyethyl)ethylenediamine are reacted to obtain a polyhydroxy compound containing a diaminal 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 to obtain a solution of polysiloxane polyurea polymer Z through reaction;

[0011] (3) Mixing a solution of a polyhydroxy compound containing a diaminal bond and a polysiloxane polyurea polymer Z, reacting, and drying to obtain a high-strength and high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing a dynamic aminal bond.

[0012] Preferably, in step (1), the molar ratio of terephthalaldehyde to N,N'-bis(2-hydroxyethyl)ethylenediamine is 1:(2-2.3); and the volume ratio of terephthalaldehyde to anhydrous ethanol is 1g:5-100ml.

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

[0014] Preferably, according to 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] Preferably, in step (1), the post-treatment method of the reaction solution obtained by the reaction is as follows: the reaction solution is filtered, and the obtained precipitate is recrystallized from ethyl acetate to obtain a polyhydroxy compound containing a diaminal bond.

[0016] Preferably, according to the present invention, in step (1), the polyhydroxy compound containing a diaminal bond has a structure shown in formula (I):

[0017]

[0018] According to the 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 volume ratio of the total mass of diisocyanate a and aminopropyl-terminated polydimethylsiloxane to solvent A is 1g:0.5-28ml, preferably 1g:0.5-18ml.

[0019] Preferably according to the present invention, in step (2), the diisocyanate a is toluene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, hexamethylene diisocyanate, methylcyclohexyl diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, p-phenylene diisocyanate, p-xylylene diisocyanate or tetramethylxylene diisocyanate, or a combination of two or more thereof.

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

[0021] Preferably according to 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 a structure as shown in the following formula (II):

[0023]

[0024] Preferably, in step (2), the aminopropyl-terminated polydimethylsiloxane is added dropwise into 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 solvent A, and the concentration of the aminopropyl-terminated polydimethylsiloxane solution is 0.1-0.5 g / mL; and the protective gas is nitrogen or argon.

[0025] Preferably according to 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, the reaction time is 30 to 480 min, preferably 30 to 300 min, and the reaction is carried out under stirring conditions and protective gas protection; preferably, the protective gas is nitrogen or argon.

[0026] Preferably, in step (2) of the present invention, the method for preparing a solution of an isocyanate-terminated prepolymer X comprises the steps of: mixing a diisocyanate a and a solvent A1, adding dropwise a mixed solution of an aminopropyl-terminated polydimethylsiloxane and a solvent A2 under stirring and protective gas protection, and obtaining a solution of an isocyanate-terminated prepolymer X through reaction; 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 a structure as shown in the following formula (III):

[0028]

[0029]

[0030] According to the 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 volume ratio of the total mass of 1,3-bis(3-aminopropyl)tetramethyldisiloxane and diisocyanate b to solvent B is 1g:2-15ml, preferably 1g:2-10ml.

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

[0032] Preferably according to 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] Preferably, in step (2), diisocyanate b is added dropwise into the reaction system in the form of a diisocyanate b solution under stirring and protective gas protection; the type of solvent used for the diisocyanate b solution is the same as solvent B, and the concentration of the diisocyanate b solution is 1-2 g / mL; the protective gas is nitrogen or argon.

[0034] Preferably according to 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, the reaction time is 1 to 2 min, and the reaction is carried out under stirring conditions and under the protection of a protective gas; preferably, the protective gas is nitrogen or argon.

[0035] Preferably, according to the present invention, in step (2), the method for preparing a solution of aminopropyl-terminated prepolymer Y comprises the steps of: mixing 1,3-bis(3-aminopropyl)tetramethyldisiloxane and solvent B1, adding dropwise a mixed solution of diisocyanate b and solvent B2 under stirring and protective gas protection, and obtaining a solution of aminopropyl-terminated prepolymer Y through reaction; preferably, the types of solvent B1 and solvent B2 are the same as solvent B, and the total volume of solvent B1 and solvent B2 is the same as solvent B.

[0036] Preferably, according to the present invention, in step (2), the aminopropyl-terminated prepolymer Y has a structure as shown in the following formula (IV):

[0037]

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

[0039] Preferably, in step (2), the solution of aminopropyl-terminated prepolymer Y is added dropwise to the solution of isocyanate-terminated prepolymer X under protection of protective gas and stirring. Preferably, the protective gas is nitrogen or argon.

[0040] Preferably, according to the present invention, in step (2), the reaction temperature after mixing the solution of the isocyanate-terminated prepolymer X and the solution of the aminopropyl-terminated prepolymer Y is 20 to 75° C., the reaction time is 60 to 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 a structure as shown in the following formula (V):

[0042]

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

[0044] Preferably, according to 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] Preferably, according to the present invention, in step (3), the drying method is as follows: standing at room temperature for 8-18 hours, and then vacuum drying at 60-80°C for 20-30 hours.

[0046] A high-strength and high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing dynamic aminal bonds is prepared by the method.

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

[0048] 1. The present invention adopts a copolymer of diisocyanate and macromolecular aminopropyl-terminated polydimethylsiloxane as a soft segment, and a copolymer of diisocyanate and 1,3-bis(3-aminopropyl)tetramethyldisiloxane as a hard segment to prepare a polysiloxane polyurea type elastomer. The soft and hard segments have similar structures, which increases the compatibility of the two phases, greatly improves the reaction efficiency, avoids macroscopic phase separation, and improves the elongation at break of the polysiloxane polyurea elastomer under the condition of high hard segment content. The obtained elastomer has high mechanical strength and can fully reflect the performance advantages of polysiloxane.

[0049] 2. Using a polyhydroxy compound containing a dynamic aminal bond as a crosslinking agent, a dynamic covalent crosslinking network that can dissociate at high temperature is introduced into a polysiloxane polyurea elastomer to obtain a thermoplastic elastomer, which further enhances the mechanical properties of the elastomer, while enabling the elastomer to have a high thermoplasticization temperature and a high use temperature. It can maintain good dimensional stability at a high working temperature and can be processed repeatedly. The above-mentioned aminal bond is a dynamic covalent bond. The elastomer prepared using a compound containing the dynamic bond as a crosslinking agent will maintain the same dissociation rate and association rate over a wide temperature range. There is a constant number of aminal crosslinking points in the system, and the crosslinking structure remains stable. When the temperature rises above the thermoplasticization temperature, the dissociation rate is greater than the association rate, the network crosslinking density decreases, and the elastomer can be reshaped.

[0050] 3. The preparation process of the present invention is simple and feasible, the product performance is stable, and the reproducibility is good, which is suitable for promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is the H NMR spectrum of compound C prepared in Example 1 of the present invention;

[0052] Figure 2 This is an infrared spectrum of the elastomer prepared in Example 1 of the present invention;

[0053] Figure 3 This is a thermoplastic temperature test chart of the elastomer prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0054] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solution of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] The experimental methods in the following examples are conventional methods unless otherwise specified, and the experimental materials used in the following examples are commercially available unless otherwise specified.

[0056] Test description:

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

[0058] The infrared spectrum test was carried out by Bruker Tensor 27 infrared spectrometer. The sample was pressed into potassium bromide tablets and sampled 16 times. The frequency collection range was from 4000 cm -1 Up to 400cm -1 , resolution 4cm -1 .

[0059] The mechanical properties test of the samples was conducted on an Instron 3343 material testing system. According to GB / T 1040-2006, the thin slices obtained by hot pressing the solid samples at 180°C and 15MPa for 15 minutes were cut into dumbbell-shaped specimens, and the mechanical properties of the materials were determined by stress-strain analysis, and at least three parallel tests were performed.

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

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

[0062] Example 1

[0063] A method for preparing a high-strength and high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing dynamic aminal bonds, comprising the steps of:

[0064] Step 1: Add N,N'-bis(2-hydroxyethyl)ethylenediamine (32.6 g, 0.22 mol) and excess anhydrous magnesium sulfate (to fully remove the water generated by the reaction) to a solution of terephthalaldehyde (13.4 g, 0.1 mol) in anhydrous ethanol (100 mL). Stir the resulting suspension at 60°C for 36 hours and then filter. The resulting precipitate is purified by recrystallization from ethyl acetate to obtain a yellow crystalline polyhydroxy compound containing a diaminal bond, which is designated as C.

[0065] Step 2: Under 0°C, 1311.75 mg (0.005 mol) of HMDI (dicyclohexylmethane diisocyanate) and 10 ml of tetrahydrofuran were added to a flask equipped with a nitrogen conduit, a constant pressure dropping funnel, a condenser and a stirring device. The mixture was passed through nitrogen and stirred rapidly. A tetrahydrofuran solution of Mw=1000 g / mol bis(3-aminopropyl)-terminated polydimethylsiloxane (wherein the content of bis(3-aminopropyl)-terminated polydimethylsiloxane was 3000 mg and the volume of tetrahydrofuran was 15 mL) was added dropwise from the dropping funnel. After the addition was completed, the reaction was continued to stir at 0°C for 5 h to obtain a solution of an isocyanate-terminated prepolymer X.

[0066] Step 3: 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 conduit, a constant pressure dropping funnel, a condenser and a stirring device at 0°C, pass nitrogen and stir rapidly, add dropwise a mixed solution of 784.05 mg (0.003 mol) of HMDI (dicyclohexylmethane diisocyanate) and 5 ml of isopropanol from the dropping funnel, continue stirring the reaction at 0°C for 2 min after the rapid addition, and 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, pass nitrogen gas, stir rapidly, and add dropwise to the solution of isocyanate-terminated prepolymer X obtained in step 2. After the dropwise addition is completed, stir and react at 45° C. for 5 h 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, continue stirring at 45°C for 1 hour, and then end. The product is transferred to a polytetrafluoroethylene mold, dried at room temperature for 12 hours, and then placed in a vacuum oven at 80°C for 24 hours to obtain a high-strength and high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing dynamic aminal bonds.

[0069] The H NMR spectrum of compound C obtained in this example is as follows Figure 1 As shown, it is proved that the target product was successfully prepared.

[0070] The FTIR spectrum of the high-strength and high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing dynamic aminal bonds obtained in this example 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, 1700cm -1 The absorption peak at is the stretching vibration peak of carbonyl C=O. The FTIR spectrum proves that the target product is successfully prepared.

[0071] The high-strength and high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing dynamic aminal bonds obtained in this example has a tensile strength of 27 MPa and an elongation at break of 193%.

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

[0073] Example 2

[0074] A method for preparing a high-strength and high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing dynamic aminal bonds, comprising the steps of:

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

[0076] Step 2: At 0°C, 1112 mg (0.005 mol) of IPDI (isophorone diisocyanate) and 10 ml of isopropanol were added to a flask equipped with a nitrogen conduit, a constant pressure dropping funnel, a condenser and a stirring device. The mixture was passed through nitrogen and stirred rapidly. An isopropanol solution of bis(3-aminopropyl)-terminated polydimethylsiloxane having a Mw of 1000 g / mol was added dropwise from the dropping funnel (wherein the content of bis(3-aminopropyl)-terminated polydimethylsiloxane was 3003 mg and the volume of isopropanol was 10 mL). After the addition was completed, the reaction was continued to stir at 0°C for 4 h to obtain a solution of an isocyanate-terminated prepolymer X.

[0077] Step 3: 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 inlet, a constant pressure dropping funnel, a condenser and a stirring device at -10°C, pass nitrogen and stir rapidly, add a mixture of 750.85 mg (0.003 mol) of MDI and 5 ml of dichloromethane dropwise from the dropping funnel, continue stirring and react at -10°C for 2 min after the addition is completed, and 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, pass nitrogen gas, stir rapidly, and add dropwise to the solution of isocyanate-terminated prepolymer X obtained in step 2. After the dropwise addition is completed, stir and react at 50° C. for 5 h 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, continue stirring at 50°C for 3 hours, and then end. The product is transferred to a polytetrafluoroethylene mold, dried at room temperature for 12 hours, and then placed in a vacuum oven at 80°C for 24 hours to obtain a high-strength and high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing dynamic aminal bonds.

[0080] The high-strength and high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing dynamic aminal bonds obtained in this example has a tensile strength of 16.32 MPa and an elongation at break of 287%.

[0081] The high-strength and high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing dynamic aminal bonds obtained in this embodiment has a thermoplastic temperature of 115°C.

[0082] Example 3

[0083] A method for preparing a high-strength and high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing dynamic aminal bonds, comprising the steps of:

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

[0085] Step 2: Under the condition of -10°C, 1312mg (0.005mol) of HMDI (dicyclohexylmethane diisocyanate) and 5ml of toluene were added to a flask with a nitrogen conduit, a constant pressure dropping funnel, a condenser and a stirring device. The mixture was passed through nitrogen and stirred rapidly. A toluene solution of Mw=1000g / mol bis(3-aminopropyl)-terminated polydimethylsiloxane (wherein the content of bis(3-aminopropyl)-terminated polydimethylsiloxane was 4000mg and the volume of toluene was 15mL) was added dropwise from the dropping funnel. After the addition was completed, the reaction was continued to stir at -10°C for 4h to obtain a solution of an isocyanate-terminated prepolymer X.

[0086] Step 3: 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 inlet, a constant pressure dropping funnel, a condenser and a stirring device at -10°C, pass nitrogen and stir rapidly, and add a mixed solution of 1050 mg (0.004 mol) of HMDI and 5 ml of dichloromethane dropwise from the dropping funnel. After the addition is completed, continue stirring the reaction at -10°C 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, pass nitrogen gas, stir rapidly, and add dropwise to the solution of isocyanate-terminated prepolymer X obtained in step 2. After the dropwise addition is completed, 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, continue stirring at 30°C for 1 hour, and then end. The product is transferred to a polytetrafluoroethylene mold, dried at room temperature for 12 hours, and then placed in a vacuum oven at 80°C for 24 hours to obtain a high-strength and high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing dynamic aminal bonds.

[0089] The high-strength and high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing dynamic aminal bonds obtained in this example has a tensile strength of 28.32 MPa and an elongation at break of 125.7%.

[0090] The high-strength and high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing dynamic aminal bonds obtained in this embodiment has a thermoplastic temperature of 135°C.

[0091] Example 4

[0092] A method for preparing a high-strength and high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing dynamic aminal bonds, comprising the steps of:

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

[0094] Step 2: Under the condition of -10°C, 1311.5 mg (0.005 mol) of HMDI and 5 ml of toluene were added to a flask equipped with a nitrogen conduit, a constant pressure dropping funnel, a condenser and a stirring device. The mixture was passed through nitrogen and stirred rapidly. A toluene solution of bis(3-aminopropyl)-terminated polydimethylsiloxane having a Mw of 5000 g / mol (wherein the content of bis(3-aminopropyl)-terminated polydimethylsiloxane was 20 g and the volume of toluene was 100 mL) was added dropwise from the dropping funnel. After the addition was completed, the reaction was continued to stir at -10°C for 4 h to obtain a solution of an isocyanate-terminated prepolymer X.

[0095] Step 3: 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 conduit, a constant pressure dropping funnel, a condenser and a stirring device at -10°C, pass nitrogen and stir rapidly, add a mixed solution of 1053 mg (0.004 mol) of HMDI and 10 ml of n-hexane dropwise from the dropping funnel, continue stirring the reaction at -10°C for 2 min after the addition is completed, and 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, pass nitrogen gas, stir rapidly, and add dropwise to the solution of isocyanate-terminated prepolymer X obtained in step 2. After the dropwise addition is completed, 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, continue stirring at 50°C for 5 hours, and then end. The product is transferred to a polytetrafluoroethylene mold, dried at room temperature for 12 hours, and then placed in a vacuum oven at 80°C for 24 hours to obtain a high-strength and high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing dynamic aminal bonds.

[0098] The high-strength and high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing dynamic aminal bonds obtained in this example has a tensile strength of 7.52 MPa and an elongation at break of 186.9%.

[0099] The high-strength and high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing dynamic aminal bonds obtained in this example 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 to 2 of this comparative example are the same as steps 2 to 3 of Example 1;

[0103] Step 3: The solution of aminopropyl-terminated prepolymer Y obtained in step 2 is transferred to a dropping funnel, nitrogen is passed through, rapid stirring is performed, and dropwise addition is made to the solution of isocyanate-terminated prepolymer X obtained in step 2. After the addition is completed, stirring is performed at 45°C for 6 hours. The product is transferred to a polytetrafluoroethylene mold, dried at room temperature for 12 hours, and then placed in a vacuum oven at 80°C for 24 hours to obtain an 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°C.

[0106] The difference between this comparative example and Example 1 is that the polyhydroxy compound C containing dynamic covalent aminal bonds is not added, and a dynamic covalent cross-linked network structure is not formed, so 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°C

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

Claims

1. A method for preparing a high-strength and high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing dynamic aminal bonds, comprising the steps of: (1) In anhydrous ethanol, terephthalaldehyde and N,N'-bis(2-hydroxyethyl)ethylenediamine are reacted to obtain a polyhydroxy compound containing a diaminal 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 to obtain a solution of polysiloxane polyurea polymer Z through reaction; (3) Mixing a solution of a polyhydroxy compound containing a diaminal bond and a polysiloxane polyurea polymer Z, reacting, and drying to obtain a high-strength and high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing a dynamic aminal bond.

2. The method for preparing a high-strength and high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing dynamic aminal bonds according to claim 1, characterized in that: In step (1), one or more of the following conditions are included: 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 by the reaction; iii. The reaction temperature is 55-65°C, the reaction time is 30-40h, and the reaction is carried out under stirring conditions.

3. The method for preparing a high-strength and high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing dynamic aminal bonds according to claim 1, characterized in that: In step (2), one or more of the following conditions are included: i. 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 volume ratio of the total mass of diisocyanate a and aminopropyl-terminated polydimethylsiloxane to solvent A is 1g:0.5-28ml, preferably 1g:0.5-18ml; 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, p-phenylene diisocyanate, p-xylylene diisocyanate or tetramethylxylylene diisocyanate; iii. The molar ratio of diisocyanate a to aminopropyl-terminated polydimethylsiloxane is (1-2):1; iv. the weight average molecular weight of the aminopropyl terminated polydimethylsiloxane is 500-20000 g / mol, preferably 1000-5000 g / mol; v. The aminopropyl-terminated polydimethylsiloxane is added dropwise into the reaction system in the form of an aminopropyl-terminated polydimethylsiloxane solution under stirring and protection of a protective gas; 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; vi. 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 and protective gas protection; preferably, the protective gas is nitrogen or argon.

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

5. The method for preparing a high-strength and high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing dynamic aminal bonds according to claim 1, characterized in that: In step (2), one or more of the following conditions are included: i. 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 volume ratio of the total mass of 1,3-bis(3-aminopropyl)tetramethyldisiloxane and diisocyanate b to solvent B is 1g:2-15ml, preferably 1g:2-10ml; ii. diisocyanate b is one or a combination of two or more of hexamethylene diisocyanate, isophorone diisocyanate (IPDI), diphenylmethane-4,4'-diisocyanate (MDI), xylylene diisocyanate, toluene diisocyanate (TDI), tetramethylxylylene 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 into the reaction system in the form of a diisocyanate b solution under stirring and protective gas protection; the type of solvent used for the diisocyanate b solution is the same as solvent B, and the concentration of the diisocyanate b solution is 1-2 g / mL; the protective gas is nitrogen or argon; v. 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 and protective gas protection; preferably, the protective gas is nitrogen or argon.

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

7. The method for preparing a high-strength and high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing dynamic aminal bonds according to claim 1, characterized in that: In step (2), one or more of the following conditions are included: i. The molar ratio of 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 protective gas protection and stirring; preferably, the protective gas is nitrogen or argon; iii. The reaction temperature after mixing the solution of the isocyanate-terminated prepolymer X and the solution of the aminopropyl-terminated prepolymer Y is 20 to 75° C., the reaction time is 60 to 300 min, and the reaction is carried out under stirring.

8. The method for preparing a high-strength and high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing dynamic aminal bonds according to claim 1, characterized in that: In step (3), the mass ratio of the polyhydroxy compound containing a diacetal amine bond to the diisocyanate a in step (2) is 1:3-12, preferably 1:5-11.

3.

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

10. A high-strength and high-thermoplastic-temperature polysiloxane polyurea thermoplastic elastomer containing dynamic aminal bonds, prepared by the method according to any one of claims 1 to 9.

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