Polyurethane elastomer as well as preparation method and application thereof

Abstract

The invention relates to the technical field of elastomer materials, and provides a polyurethane elastomer as well as a preparation method and application thereof. Polyamic acid is adopted as a chain extender, and a rigid polyamic acid chain segment is introduced into a polyurethane matrix, so that the tensile strength is enhanced, and the polyurethane elastomer has relatively high mechanical performance and shows excellent shape memory performance at relatively high temperature. Furthermore, Eu < 3 + > is introduced into the polyurethane elastomer and coordinated with-COOH in a polyurethane matrix, and the cross-linking density of polyurethane is enhanced by utilizing the high bond energy of a coordinate bond, so that the shape memory performance of the polyurethane elastomer is further improved, and higher shape fixation rate and recovery rate are shown; meanwhile, due to the introduction of Eu < 3 + >, the polyurethane elastomer shows fluorescence characteristics and has a wide application prospect in the fields of anti-counterfeiting coatings and the like.

Description

Technical Field

[0001] The invention relates to the technical field of elastomer materials, and in particular to a polyurethane elastomer and a preparation method and application thereof. Background Art

[0002] Polyurethane is a polymer material with excellent mechanical properties, media resistance and self-lubricating properties. It is widely used in sealing materials, water-lubricated bearings and other fields. Polyurethane is mainly made of isocyanate and polyol through polycondensation reaction. Its molecular structure includes hard segment and soft segment. The hard segment provides strength and hardness, while the soft segment gives the material elasticity and toughness. High-toughness polyurethane usually has a high-flow soft segment, which makes its glass transition temperature low, limiting its application in thermally induced shape memory materials.

[0003] Therefore, how to increase the glass transition temperature of polyurethane while achieving high strength and high toughness remains a difficult problem to be solved urgently in this field. Summary of the invention

[0004] In view of this, the present invention provides a polyurethane elastomer and a preparation method and application thereof. The polyurethane elastomer provided by the present invention has excellent mechanical properties, a high glass transition temperature and excellent shape memory properties, and can be used in complex environments; further, the present invention also introduces Eu into the polyurethane 3+ , which can further improve the shape memory performance and at the same time make the obtained polyurethane elastomer have fluorescent properties.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] A polyurethane elastomer comprises the following raw materials in parts by weight: 10-20 parts of polytetrahydrofuran, 20-30 parts of toluene diisocyanate, and 1-9 parts of a chain extender; the chain extender is polyamic acid; the raw materials for preparing the polyamic acid include 2,2-bis(4-aminophenyl)hexafluoropropane and 4,4'-(hexafluoroisopropylene) dipeptide anhydride.

[0007] Preferably, the weight average molecular weight of the polyamic acid is 4227-8120.

[0008] Preferably, the polyamic acid is used in the form of a solution containing polyamic acid, and the preparation method of the solution containing polyamic acid comprises: mixing 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-(hexafluoroisopropylene) dipeptide anhydride and a polar solvent for polymerization reaction to obtain a solution containing polyamic acid; the polymerization reaction temperature is 0°C, and the reaction time is 12 to 24 hours; the molar ratio of 2,2-bis(4-aminophenyl)hexafluoropropane to 4,4'-(hexafluoroisopropylene) dipeptide anhydride is 1.1 to 1.2:1.

[0009] Preferably, the raw materials for preparing the polyurethane elastomer further include 1 to 5 parts of europium nitrate in terms of molar mass.

[0010] The present invention also provides a method for preparing the polyurethane elastomer described in the above scheme, comprising the following steps:

[0011] The polytetrahydrofuran, toluene diisocyanate and a polar solvent are mixed to carry out a prepolymerization reaction to obtain an isocyanate-terminated prepolymer;

[0012] The isocyanate-terminated prepolymer, polyamic acid and a catalyst are mixed to carry out a polymerization reaction, and the obtained polymerization reaction liquid is cast and then the solvent is removed to obtain the polyurethane elastomer.

[0013] Preferably, the temperature of the prepolymerization reaction is 70-90° C., and the reaction time is 1-2 hours; the temperature of the polymerization reaction is 70-90° C., and the reaction time is 3-8 hours.

[0014] Preferably, when the raw materials for preparing the polyurethane elastomer further include europium nitrate, the method further includes mixing the polymerization reaction solution and the europium nitrate solution, and then casting the obtained mixed solution.

[0015] Preferably, the temperature of the solvent removal is 70-90° C. and the time is 30-50 hours.

[0016] The present invention also provides the polyurethane elastomer described in the above scheme or the polyurethane elastomer prepared by the preparation method described in the above scheme (excluding Eu 3+ ) in shape memory materials.

[0017] The present invention also provides the polyurethane elastomer described in the above scheme or the polyurethane elastomer prepared by the preparation method described in the above scheme (including Eu 3+ ) in shape memory materials or anti-counterfeiting coatings.

[0018] The present invention provides a polyurethane elastomer, comprising the following raw materials in the following amounts: 10 to 20 parts of polytetrahydrofuran, 20 to 30 parts of toluene diisocyanate, and 1 to 9 parts of a chain extender; the chain extender is polyamic acid; the raw materials for preparing the polyamic acid include 2,2-bis(4-aminophenyl)hexafluoropropane and 4,4'-(hexafluoroisopropylene) dipeptide anhydride. The present invention introduces a rigid polyamic acid segment into a polyurethane matrix, and utilizes the rigid segment and its tendency to form π-π conjugation to make the polyurethane exhibit a higher density of hydrogen bonds, thereby enhancing the mechanical properties and providing it with excellent tensile strength and toughness; at the same time, the hydrogen bond network structure of the polyurethane is utilized to enable it to exhibit excellent shape memory properties at higher temperatures. In summary, the polyurethane elastomer provided by the present invention has excellent shape memory properties, excellent mechanical properties, and a higher glass transition temperature, can be used in complex environments, and provides a new strategy for developing high-performance shape memory polyurethanes.

[0019] Furthermore, the raw materials for preparing the polyurethane elastomer provided by the present invention also include 1 to 5 parts of europium nitrate. 3+ , coordinate it with -COOH in the polyurethane matrix, and use the high bond energy of the coordination bond to enhance the cross-linking density of the polyurethane, thereby further improving the shape memory properties of the polyurethane elastomer, showing a higher shape fixation rate and recovery rate; at the same time, Eu 3+ The introduction of also makes the polyurethane elastomer exhibit fluorescent properties, and the shape memory process can be observed under ultraviolet light. This unique property gives the material broad application prospects in fields such as anti-counterfeiting coatings.

[0020] The present invention also provides a method for preparing the polyurethane elastomer described in the above scheme. The preparation method provided by the present invention has readily available raw materials and is simple to operate, and is expected to be commercialized. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The stress-strain curves of the polyurethane elastomers prepared in Examples 1 to 5 and Comparative Example 1;

[0022] Figure 2 The tan δ curves of the polyurethane elastomers prepared in Examples 1 to 5;

[0023] Figure 3 This is a shape memory cycle curve diagram of the polyurethane elastomer prepared in Example 2;

[0024] Figure 4 This is a shape memory cycle curve diagram of the polyurethane elastomer prepared in Example 9;

[0025] Figure 5 These are the emission spectra of the polyurethane elastomers prepared in Examples 2 and 9. DETAILED DESCRIPTION

[0026] The invention provides a polyurethane elastomer, comprising the following raw materials in parts by weight: 10 to 20 parts of polytetrahydrofuran, 20 to 30 parts of toluene diisocyanate, and 1 to 9 parts of a chain extender; the chain extender is polyamic acid; the raw materials for preparing the polyamic acid include 2,2-bis(4-aminophenyl)hexafluoropropane and 4,4'-(hexafluoroisopropylene) dipeptide anhydride.

[0027] In the present invention, the weight average molecular weight of the polytetrahydrofuran is preferably 2,000.

[0028] In the present invention, the amount of the polytetrahydrofuran is preferably 10 parts; the amount of the toluene diisocyanate is preferably 20 parts.

[0029] In the present invention, the amount of the chain extender is preferably 3 parts; the weight average molecular weight of the polyamic acid is preferably 4227-8120, more preferably 5000.

[0030] In the present invention, the polyamic acid is preferably used in the form of a solution containing polyamic acid. The preparation method of the solution containing polyamic acid preferably comprises: mixing 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-(hexafluoroisopropylene) dipeptide anhydride and a polar solvent for polymerization reaction to obtain a solution containing polyamic acid; the polymerization reaction temperature is preferably 0°C, the reaction time is preferably 12 to 24 hours, and the polymerization reaction is preferably carried out under argon protection; in a specific embodiment of the present invention, the polymerization reaction is preferably carried out under ice bath conditions; the molar ratio of 2,2-bis(4-aminophenyl)hexafluoropropane to 4,4'-(hexafluoroisopropylene) dipeptide anhydride is preferably 1.1 to 1.2:1, more preferably 1.167:1; the polar solvent is preferably one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, toluene and tetrahydrofuran, more preferably N,N-dimethylformamide, specifically anhydrous N,N-dimethylformamide. In a specific embodiment of the present invention, it is preferred to first dissolve 2,2-bis(4-aminophenyl)hexafluoropropane and 4,4'-(hexafluoroisopropylene) dipeptide anhydride in polar solvents respectively, then dropwise add the 4,4'-(hexafluoroisopropylene) dipeptide anhydride solution into the 2,2-bis(4-aminophenyl)hexafluoropropane solution, and carry out the polymerization reaction in an ice bath, under argon protection and under stirring conditions.

[0031] In a specific embodiment of the present invention, after obtaining the solution containing polyamic acid, it can be directly used to synthesize the polyurethane elastomer without any treatment, which will be described in detail later; the solid content of the solution containing polyamic acid is preferably 15%.

[0032] In the present invention, the raw material for preparing the polyurethane elastomer preferably further comprises 1 to 5 parts of europium nitrate, based on the amount of the substance; the europium nitrate is preferably europium (III) nitrate hexahydrate; the Eu in the europium nitrate is preferably 3+ The molar ratio of -COOH in the polyurethane matrix is ​​preferably 0.25-1.25:9; the polyurethane matrix is ​​the polymer matrix obtained by the reaction before adding europium nitrate.

[0033] In the present invention, the polyurethane elastomer prepared from raw materials without europium nitrate is recorded as PU-PAA, and the tensile strength of the PU-PAA is ≥49MPa, the elongation at break is ≥161%, and the toughness is ≥59MJ / m 3 ; The polyurethane elastomer prepared by raw materials including europium nitrate is recorded as PU-PAA-Eu, and the tensile strength of the PU-PAA-Eu is ≥50MPa, the shape fixation rate is ≥88%, and the shape recovery rate is ≥98%.

[0034] The present invention also provides a method for preparing the polyurethane elastomer described in the above scheme, comprising the following steps:

[0035] The polytetrahydrofuran, toluene diisocyanate and a polar solvent are mixed to carry out a prepolymerization reaction to obtain an isocyanate-terminated prepolymer;

[0036] The isocyanate-terminated prepolymer, polyamic acid and a catalyst are mixed to carry out a polymerization reaction, and the obtained polymerization reaction liquid is cast and then the solvent is removed to obtain the polyurethane elastomer.

[0037] The present invention mixes polytetrahydrofuran, toluene diisocyanate and a polar solvent for prepolymerization to obtain an isocyanate-terminated prepolymer. In the present invention, the polar solvent is preferably one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, toluene and tetrahydrofuran, more preferably N,N-dimethylformamide, specifically anhydrous N,N-dimethylformamide; the temperature of the prepolymerization reaction is preferably 70 to 90°C, more preferably 80°C, and the time of the prepolymerization reaction is preferably 1 to 2 hours. In a specific embodiment of the present invention, it is preferred to first melt polytetrahydrofuran at 70 to 90°C, then add toluene diisocyanate and a polar solvent, then keep warm and carry out the prepolymerization reaction under argon protection and stirring conditions.

[0038] After obtaining the isocyanate-terminated prepolymer, the present invention mixes the isocyanate-terminated prepolymer, polyamic acid and a catalyst to carry out a polymerization reaction, and the obtained polymerization reaction liquid is cast and then desolventized to obtain the polyurethane elastomer. In the present invention, the polymerization reaction temperature is preferably 70 to 90°C, and the reaction time is preferably 3 to 8 hours; the catalyst is preferably an organic tin catalyst, more preferably dibutyltin dilaurate; the amount of the catalyst is preferably 0.5 to 1.0% of the mass of the prepolymer; in a specific embodiment of the present invention, after the prepolymer reaction is completed, the present invention drips a solution containing polyamic acid into the obtained prepolymer solution, and then adds a catalyst to carry out a polymerization reaction.

[0039] In the present invention, when the raw materials for preparing the polyurethane elastomer also include europium nitrate, it is preferred to mix the polymerization reaction solution and the europium nitrate solution, and then cast the resulting mixed solution; the europium nitrate solution is preferably prepared from europium nitrate and a polar solvent; the polar solvent is preferably one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, toluene and tetrahydrofuran, more preferably N,N-dimethylformamide, specifically anhydrous N,N-dimethylformamide.

[0040] In the present invention, the casting mold is preferably a Teflon mold.

[0041] In the present invention, the temperature of the solvent removal is preferably 70-90°C, preferably 80°C, and the time of the solvent removal is preferably 30-50h, more preferably 48h; after the solvent removal is completed, the polyurethane elastomer can be obtained by cooling to room temperature and demolding.

[0042] The present invention also provides the use of the polyurethane elastomer (PU-PAA) described in the above scheme or the polyurethane elastomer (PU-PAA) prepared by the preparation method described in the above scheme in shape memory materials.

[0043] The present invention also provides the use of the polyurethane elastomer (PU-PAA-Eu) described in the above scheme or the polyurethane elastomer (PU-PAA-Eu) prepared by the preparation method described in the above scheme in shape memory materials or anti-counterfeiting coatings.

[0044] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions 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.

[0045] The sources of the various raw materials used in the examples are as follows: bis(4-aminophenyl)hexafluoropropane from Sane Chemical Technology (Shanghai) Co., Ltd.; 4,4'-(hexafluoroisopropylene) dipeptide anhydride from Anhui Zesheng Technology Co., Ltd.; polytetrahydrofuran from Jining Hongming Chemical Reagent Co., Ltd.; toluene diisocyanate from Shanghai Sanyou Reagent Co., Ltd.; 1,6-hexanediamine from Sane Chemical Technology (Shanghai) Co., Ltd.; dibutyltin dilaurate from Tianjin Chemical Reagent Factory; N,N-dimethylformamide from Lianlong Bohua (Tianjin) Pharmaceutical Chemical Co., Ltd.; europium nitrate (III) hexahydrate from Anhui Senri Technology Co., Ltd. 10-20 parts of polytetrahydrofuran, 20-30 parts of toluene diisocyanate, 1-9 parts of chain extender

[0046] Example 1

[0047] 29.17 mmol of 2,2-bis(4-aminophenyl)hexafluoropropane was dissolved in 50 mL of anhydrous N,N-dimethylformamide in a three-necked flask, and then 25 mmol of 4,4'-(hexafluoroisopropylene) dipeptide anhydride was dissolved in 75 mL of anhydrous N,N-dimethylformamide. The solution was slowly added dropwise to the three-necked flask, and then mechanically stirred in an ice bath under an argon atmosphere for 12 hours to obtain a polyamic acid (PAA) solution, wherein the relative molecular mass (Mw) of PAA was 5000, the PAA solution was a yellow viscous liquid, and the solid content was 15%; the PAA solution was directly used to synthesize polyurethane without any post-treatment.

[0048] 2.5 mmol of polytetrahydrofuran (weight average molecular weight: 2000) was melted in a three-necked flask at 80°C, and then 5 mmol of toluene diisocyanate and 15 mL of anhydrous N,N-dimethylformamide were added, followed by mechanical stirring at 80°C under an argon atmosphere for 1 hour to react and generate an isocyanate-terminated prepolymer.

[0049] A solution containing 0.5 mmol of PAA was added to the prepolymer solution, and 50 μL of dibutyltin dilaurate was added to catalyze the reaction at 80°C for 4 hours. After the reaction was completed, the solution was poured into a Teflon mold, placed in an oven to remove the solvent, cooled to room temperature, and demolded to obtain a polyurethane elastomer (PU-PAA1).

[0050] Example 2

[0051] 29.17 mmol of 2,2-bis(4-aminophenyl)hexafluoropropane was dissolved in 50 mL of anhydrous N,N-dimethylformamide in a three-necked flask, and then 25 mmol of 4,4'-(hexafluoroisopropylene) dipeptide anhydride was dissolved in 75 mL of anhydrous N,N-dimethylformamide. The solution was slowly added dropwise to the three-necked flask, and then mechanically stirred in an ice bath under an argon atmosphere for 12 hours to obtain a polyamic acid (PAA) solution, wherein the relative molecular mass (Mw) of PAA was 5000, the PAA solution was a yellow viscous liquid, and the solid content was 15%; the PAA solution was directly used to synthesize polyurethane without any post-treatment.

[0052] 2.5 mmol of polytetrahydrofuran (weight average molecular weight: 2000) was melted in a three-necked flask at 80°C, and then 5 mmol of toluene diisocyanate and 15 mL of anhydrous N,N-dimethylformamide were added, followed by mechanical stirring at 80°C under an argon atmosphere for 1 hour to react and generate an isocyanate-terminated prepolymer.

[0053] A solution containing 0.75 mmol of PAA was added to the prepolymer solution, and 50 μL of dibutyltin dilaurate was added to catalyze the reaction at 80°C for 4 hours. After the reaction was completed, the solution was poured into a Teflon mold, placed in an oven to remove the solvent, cooled to room temperature, and demolded to obtain a polyurethane elastomer (PU-PAA2).

[0054] Example 3

[0055] 29.17 mmol of 2,2-bis(4-aminophenyl)hexafluoropropane was dissolved in 50 mL of anhydrous N,N-dimethylformamide in a three-necked flask, and then 25 mmol of 4,4'-(hexafluoroisopropylene) dipeptide anhydride was dissolved in 75 mL of anhydrous N,N-dimethylformamide. The solution was slowly added dropwise to the three-necked flask, and then mechanically stirred in an ice bath under an argon atmosphere for 12 hours to obtain a polyamic acid (PAA) solution, wherein the relative molecular mass (Mw) of PAA was 5000, the PAA solution was a yellow viscous liquid, and the solid content was 15%; the PAA solution was directly used to synthesize polyurethane without any post-treatment.

[0056] 2.5 mmol of polytetrahydrofuran (weight average molecular weight: 2000) was melted in a three-necked flask at 80°C, and then 5 mmol of toluene diisocyanate and 15 mL of anhydrous N,N-dimethylformamide were added, followed by mechanical stirring at 80°C under an argon atmosphere for 1 hour to react and generate an isocyanate-terminated prepolymer.

[0057] A solution containing 1.0 mmol of PAA was added to the prepolymer solution, and 50 μL of dibutyltin dilaurate was used to catalyze the reaction at 80°C for 4 h. After the reaction was completed, the solution was poured into a Teflon mold, placed in an oven to remove the solvent, cooled to room temperature, and demolded to obtain a polyurethane elastomer (PU-PAA3).

[0058] Example 4

[0059] 29.17 mmol of 2,2-bis(4-aminophenyl)hexafluoropropane was dissolved in 50 mL of anhydrous N,N-dimethylformamide in a three-necked flask, and then 25 mmol of 4,4'-(hexafluoroisopropylene) dipeptide anhydride was dissolved in 75 mL of anhydrous N,N-dimethylformamide. The solution was slowly added dropwise to the three-necked flask, and then mechanically stirred in an ice bath under an argon atmosphere for 12 hours to obtain a polyamic acid (PAA) solution, wherein the relative molecular mass (Mw) of PAA was 5000, the PAA solution was a yellow viscous liquid, and the solid content was 15%; the PAA solution was directly used to synthesize polyurethane without any post-treatment.

[0060] 2.5 mmol of polytetrahydrofuran (weight average molecular weight: 2000) was melted in a three-necked flask at 80°C, and then 5 mmol of toluene diisocyanate and 15 mL of anhydrous N,N-dimethylformamide were added, followed by mechanical stirring at 80°C under an argon atmosphere for 1 hour to react and generate an isocyanate-terminated prepolymer.

[0061] A solution containing 1.25 mmol of PAA was added to the prepolymer solution, and 50 μL of dibutyltin dilaurate was added to catalyze the reaction at 80°C for 4 hours. After the reaction was completed, the solution was poured into a Teflon mold, placed in an oven to remove the solvent, cooled to room temperature, and demolded to obtain a polyurethane elastomer (PU-PAA4).

[0062] Example 5

[0063] 29.17 mmol of 2,2-bis(4-aminophenyl)hexafluoropropane was dissolved in 50 mL of anhydrous N,N-dimethylformamide in a three-necked flask, and then 25 mmol of 4,4'-(hexafluoroisopropylene) dipeptide anhydride was dissolved in 75 mL of anhydrous N,N-dimethylformamide. The solution was slowly added dropwise to the three-necked flask, and then mechanically stirred in an ice bath under an argon atmosphere for 12 hours to obtain a polyamic acid (PAA) solution, wherein the relative molecular mass (Mw) of PAA was 5000, the PAA solution was a yellow viscous liquid, and the solid content was 15%; the PAA solution was directly used to synthesize polyurethane without any post-treatment.

[0064] 2.5 mmol of polytetrahydrofuran (weight average molecular weight: 2000) was melted in a three-necked flask at 80°C, and then 5 mmol of toluene diisocyanate and 15 mL of anhydrous N,N-dimethylformamide were added, followed by mechanical stirring at 80°C under an argon atmosphere for 1 hour to react and generate an isocyanate-terminated prepolymer.

[0065] A solution containing 1.5 mmol of PAA was added to the prepolymer solution, and 50 μL of dibutyltin dilaurate was added to catalyze the reaction at 80°C for 4 hours. After the reaction was completed, the solution was poured into a Teflon mold, placed in an oven to remove the solvent, cooled to room temperature, and demolded to obtain a polyurethane elastomer (PU-PAA5).

[0066] Example 6

[0067] 29.17 mmol of 2,2-bis(4-aminophenyl)hexafluoropropane was dissolved in 50 mL of anhydrous N,N-dimethylformamide in a three-necked flask, and then 25 mmol of 4,4'-(hexafluoroisopropylene) dipeptide anhydride was dissolved in 75 mL of anhydrous N,N-dimethylformamide. The solution was slowly added dropwise to the three-necked flask, and then mechanically stirred in an ice bath under an argon atmosphere for 12 hours to obtain a polyamic acid (PAA) solution, wherein the relative molecular mass (Mw) of PAA was 5000, the PAA solution was a yellow viscous liquid, and the solid content was 15%; the PAA solution was directly used to synthesize polyurethane without any post-treatment.

[0068] 2.5 mmol of polytetrahydrofuran (weight average molecular weight: 2000) was melted in a three-necked flask at 80°C, and then 5 mmol of toluene diisocyanate and 15 mL of anhydrous N,N-dimethylformamide were added, followed by mechanical stirring at 80°C under an argon atmosphere for 1 hour to react and generate an isocyanate-terminated prepolymer.

[0069] A solution containing 0.75 mmol of PAA was added to the prepolymer solution, and 50 μL of dibutyltin dilaurate was added to catalyze the reaction at 80°C for 4 hours. 0.281 mmol of europium (III) nitrate hexahydrate was weighed and dissolved in 10 mL of anhydrous N,N-dimethylformamide, and the solution was added to a three-necked flask and stirred for 30 minutes. After completion, the solution was poured into a Teflon mold, placed in an oven to remove the solvent, cooled to room temperature, and demolded to obtain a polyurethane elastomer (PU-PAA-Eu0.25).

[0070] Example 7

[0071] 29.17 mmol of 2,2-bis(4-aminophenyl)hexafluoropropane was dissolved in 50 mL of anhydrous N,N-dimethylformamide in a three-necked flask, and then 25 mmol of 4,4'-(hexafluoroisopropylene) dipeptide anhydride was dissolved in 75 mL of anhydrous N,N-dimethylformamide. The solution was slowly added dropwise to the three-necked flask, and then mechanically stirred in an ice bath under an argon atmosphere for 12 hours to obtain a polyamic acid (PAA) solution, wherein the relative molecular mass (Mw) of PAA was 5000, the PAA solution was a yellow viscous liquid, and the solid content was 15%; the PAA solution was directly used to synthesize polyurethane without any post-treatment.

[0072] 2.5 mmol of polytetrahydrofuran (weight average molecular weight: 2000) was melted in a three-necked flask at 80°C, and then 5 mmol of toluene diisocyanate and 15 mL of anhydrous N,N-dimethylformamide were added, followed by mechanical stirring at 80°C under an argon atmosphere for 1 hour to react and generate an isocyanate-terminated prepolymer.

[0073] A solution containing 0.75 mmol of PAA was added to the prepolymer solution, and 50 μL of dibutyltin dilaurate was added to catalyze the reaction at 80°C for 4 hours. 0.563 mmol of europium (III) nitrate hexahydrate was weighed and dissolved in 10 mL of anhydrous N,N-dimethylformamide, and the solution was added to a three-necked flask and stirred for 30 minutes. After completion, the solution was poured into a Teflon mold, placed in an oven to remove the solvent, cooled to room temperature, and demolded to obtain a polyurethane elastomer (PU-PAA-Eu0.5).

[0074] Example 8

[0075] 29.17 mmol of 2,2-bis(4-aminophenyl)hexafluoropropane was dissolved in 50 mL of anhydrous N,N-dimethylformamide in a three-necked flask, and then 25 mmol of 4,4'-(hexafluoroisopropylene) dipeptide anhydride was dissolved in 75 mL of anhydrous N,N-dimethylformamide. The solution was slowly added dropwise to the three-necked flask, and then mechanically stirred in an ice bath under an argon atmosphere for 12 hours to obtain a polyamic acid (PAA) solution, wherein the relative molecular mass (Mw) of PAA was 5000, the PAA solution was a yellow viscous liquid, and the solid content was 15%; the PAA solution was directly used to synthesize polyurethane without any post-treatment.

[0076] 2.5 mmol of polytetrahydrofuran (weight average molecular weight: 2000) was melted in a three-necked flask at 80°C, and then 5 mmol of toluene diisocyanate and 15 mL of anhydrous N,N-dimethylformamide were added, followed by mechanical stirring at 80°C under an argon atmosphere for 1 hour to react and generate an isocyanate-terminated prepolymer.

[0077] A solution containing 0.75 mmol of PAA was added to the prepolymer solution, and 50 μL of dibutyltin dilaurate was added to catalyze the reaction at 80°C for 4 hours. 0.844 mmol of europium (III) nitrate hexahydrate was weighed and dissolved in 10 mL of anhydrous N,N-dimethylformamide, and the solution was added to a three-necked flask and stirred for 30 minutes. After completion, the solution was poured into a Teflon mold, placed in an oven to remove the solvent, cooled to room temperature, and demolded to obtain a polyurethane elastomer (PU-PAA-Eu0.75).

[0078] Example 9

[0079] 29.17 mmol of 2,2-bis(4-aminophenyl)hexafluoropropane was dissolved in 50 mL of anhydrous N,N-dimethylformamide in a three-necked flask, and then 25 mmol of 4,4'-(hexafluoroisopropylene) dipeptide anhydride was dissolved in 75 mL of anhydrous N,N-dimethylformamide. The solution was slowly added dropwise to the three-necked flask, and then mechanically stirred in an ice bath under an argon atmosphere for 12 hours to obtain a polyamic acid (PAA) solution, wherein the relative molecular mass (Mw) of PAA was 5000, the PAA solution was a yellow viscous liquid, and the solid content was 15%; the PAA solution was directly used to synthesize polyurethane without any post-treatment.

[0080] 2.5 mmol of polytetrahydrofuran (weight average molecular weight: 2000) was melted in a three-necked flask at 80°C, and then 5 mmol of toluene diisocyanate and 15 mL of anhydrous N,N-dimethylformamide were added, followed by mechanical stirring at 80°C under an argon atmosphere for 1 hour to react and generate an isocyanate-terminated prepolymer.

[0081] A solution containing 0.75 mmol of PAA was added to the prepolymer solution, and 50 μL of dibutyltin dilaurate was added to catalyze the reaction at 80°C for 4 hours. 1.125 mmol of europium (III) nitrate hexahydrate was weighed and dissolved in 10 mL of anhydrous N,N-dimethylformamide, and the solution was added to a three-necked flask and stirred for 30 minutes. After completion, the solution was poured into a Teflon mold, placed in an oven to remove the solvent, cooled to room temperature, and demolded to obtain a polyurethane elastomer (PU-PAA-Eu1).

[0082] Comparative Example 1

[0083] Melt 2.5mmol polytetrahydrofuran in a three-necked flask at 80℃, then add 5mmol toluene diisocyanate and 15mL anhydrous N,N-dimethylformamide, and then mechanically stir for 1h under argon atmosphere at 80℃ to react to form an isocyanate-terminated prepolymer. Dissolve 2.5mmol 1,6-hexanediamine in 10mL N,N-dimethylformamide, add the solution to the prepolymer solution, and add 50μL dibutyltin dilaurate to catalyze the reaction at 80℃ for 4h. After the reaction is completed, pour the solution into a Teflon mold, put it in an oven to remove the solvent, cool it to room temperature, demold it, and obtain a polyurethane elastomer (PU-HMD).

[0084] Performance Test:

[0085] 1. Mechanical properties and glass transition temperature test

[0086] The mechanical properties of polyurethane elastomers were tested at room temperature using a Shimadzu AG-X (5000N) electronic universal testing machine. The tensile speed was 50 mm / min. The sample shape was cut into a dumbbell shape according to the international standard ISO-37 (Type 4). Five sample strips were tested and the average value was taken. The test results are shown in Table 1.

[0087] The transition temperature of polyurethane was verified by thermomechanical measurements in tensile mode using a Netzsch 242E dynamic mechanical analyzer, with an oscillation frequency of 1 Hz, a recording temperature range of -50°C to 150°C, and a heating rate of 5°C / min. To ensure reliable results, more than three specimens were tested for each sample. The test results are shown in Table 1.

[0088] Table 1 Mechanical properties test results

[0089]

[0090] It can be seen from the data in Table 1 that the polyurethane elastomer of the present invention has a high glass transition temperature and can maintain excellent mechanical properties, especially the tensile strength is greatly improved compared with Comparative Example 1; in Comparative Example 1, 1,6-hexanediamine is used as a chain extender. Although the elongation at break and toughness of the obtained polyurethane elastomer are high, the glass transition temperature is low and it cannot be used in the field of shape memory materials.

[0091] Figure 1 The stress-strain curves of the polyurethane elastomers prepared in Examples 1 to 5 and Comparative Example 1 are shown in FIG. Figure 1 It can be seen that the polyurethane elastomers prepared in Examples 1 to 5 have good mechanical properties. Figure 1It can be seen from the various properties of the embodiments and comparative examples that the polyurethane elastomer material prepared by the method of the present invention has excellent mechanical properties, especially the tensile strength is greatly improved, and through the proportion of polyamic acid, it is found that the mechanical properties are best when the amount of polyamic acid is 3 parts; except for Example 1, the glass transition temperatures of the other embodiments are all higher than room temperature.

[0092] Figure 2 The tan δ curves of the polyurethane elastomers prepared in Examples 1 to 5 are shown in FIG. Figure 2 It can be seen that the glass transition temperature (Tg) of PU-PAA increases with the increase of PAA content. The substantial increase in Tg may be due to the addition of the rigid segment of PAA, which enhances the π-π bonding effect and plays a role in physical cross-linking, thereby improving the fixation of the polymer chain.

[0093] 2. Shape memory performance test

[0094] The shape memory properties were tested in the tensile mode using a Netzsch 242C dynamic mechanical analyzer with a controlled load of 2 N, a shape fixing temperature of -10 °C, a shape fixing time of 5 min, a shape recovery temperature of 60 °C, a shape recovery time of 50 min, and three cycles of testing.

[0095] Figure 3 This is a shape memory cycle curve diagram of the polyurethane elastomer prepared in Example 2; Figure 4 This is a shape memory cycle curve of the polyurethane elastomer prepared in Example 9. Figure 3 and Figure 4 It can be seen that the polyurethane elastomers prepared in Examples 2 and 9 both have excellent shape memory properties; and compared with Example 2, Example 9 has a better shape memory property due to the introduction of Eu 3+ , the shape recovery rate of the obtained polyurethane elastomer is higher.

[0096] 3. Fluorescence performance test

[0097] The polyurethane elastomers prepared in Example 2 and Example 9 were subjected to fluorescence testing using an F-7000FL fluorescence spectrophotometer, and the excitation wavelength of the emission spectrum was 286 nm.

[0098] Figure 5 : This is the emission spectrum of the polyurethane elastomer prepared in Example 2 and Example 9. Figure 5 It can be seen that due to the introduction of Eu 3+ The polyurethane elastomer prepared in Example 9 has fluorescent properties and can be used in fields such as anti-counterfeiting coatings.

[0099] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A polyurethane elastomer, characterized in that: The preparation raw materials include the following substances in parts by amount: 10-20 parts of polytetrahydrofuran, 20-30 parts of toluene diisocyanate, and 1-9 parts of a chain extender; the chain extender is polyamic acid; the preparation raw materials of the polyamic acid include 2,2-bis(4-aminophenyl)hexafluoropropane and 4,4'-(hexafluoroisopropylene) dipeptide anhydride.

2. The polyurethane elastomer according to claim 1, characterized in that The weight average molecular weight of the polyamic acid is 4227-8120.

3. The polyurethane elastomer according to claim 1, characterized in that The polyamic acid is used in the form of a solution containing polyamic acid. The preparation method of the solution containing polyamic acid comprises: mixing 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-(hexafluoroisopropylene) dipeptide anhydride and a polar solvent for polymerization reaction to obtain a solution containing polyamic acid; the polymerization reaction temperature is 0°C, and the reaction time is 12 to 24 hours; the molar ratio of the 2,2-bis(4-aminophenyl)hexafluoropropane to the 4,4'-(hexafluoroisopropylene) dipeptide anhydride is 1.1 to 1.2:

1.

4. The polyurethane elastomer according to claim 1, characterized in that Calculated by weight, the raw materials for preparing the polyurethane elastomer also include 1 to 5 parts of europium nitrate.

5. The method for preparing a polyurethane elastomer according to any one of claims 1 to 3, characterized in that: The following steps are involved: The polytetrahydrofuran, toluene diisocyanate and a polar solvent are mixed to carry out a prepolymerization reaction to obtain an isocyanate-terminated prepolymer; The isocyanate-terminated prepolymer, polyamic acid and a catalyst are mixed to carry out a polymerization reaction, and the obtained polymerization reaction liquid is cast and then the solvent is removed to obtain the polyurethane elastomer.

6. The preparation method according to claim 5, characterized in that: The temperature of the prepolymerization reaction is 70-90° C., and the reaction time is 1-2 hours; the temperature of the polymerization reaction is 70-90° C., and the reaction time is 3-8 hours.

7. The preparation method according to claim 5, characterized in that: When the raw materials for preparing the polyurethane elastomer also include europium nitrate, the method further includes mixing the polymerization reaction solution and the europium nitrate solution, and then pouring the obtained mixed solution.

8. The preparation method according to claim 5 or 7, characterized in that: The temperature of the solvent removal is 70-90° C. and the time is 30-50 hours.

9. Use of the polyurethane elastomer according to any one of claims 1 to 3 or the polyurethane elastomer prepared by the preparation method according to any one of claims 5, 6 and 8 in shape memory materials.

10. Use of the polyurethane elastomer according to claim 4 or the polyurethane elastomer prepared by the preparation method according to claim 7 or 8 in shape memory materials or anti-counterfeiting coatings.

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