Chain extender containing dynamic imine bond and imidazole ring as well as preparation method and application of chain extender
Patent Information
- Application Number
- CN202510847080.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-24
- Publication Date
- 2025-10-21
AI Technical Summary
The intermolecular hydrogen bonding forces of the urethane or urea molecular structures formed by existing polyurethane chain extenders are weak, resulting in insufficient strength and toughness of the elastomers, which cannot meet the technical requirements of high-strength and tough applications such as aerospace and flexible electronic devices.
By introducing chain extenders containing dynamic imine bonds and imidazole rings, metal coordination bonds are formed through the N atoms in the imidazole rings, increasing the intermolecular forces and combining with multiple hydrogen bonding to improve the mechanical strength and toughness of the material.
The self-healing ability of polyurethane materials has been realized, and supramolecular fluorescence-triggered luminescence function has been endowed to them, thus broadening the application fields of polyurethane materials.
Smart Images
Figure CN120817899A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a chain extender containing a dynamic imine bond and an imidazole ring, a preparation method and application thereof, and belongs to the technical field of polyurethane. Background Art
[0002] Polyurethane elastomers, due to their excellent physical and mechanical properties, are widely used in various fields such as medicine, railways, and construction. They are also important materials in emerging frontier fields such as flexible wearable electronics and 3D printing. Currently, commonly used polyurethane chain extenders include aliphatic diols, aromatic diols, and aromatic diamines. After chain extension, they form carbamate or urea-based molecular structures. The intermolecular hydrogen bonding forces are weak and single, resulting in insufficient strength and toughness of the elastomers, which cannot meet the technical requirements of high-strength and toughness applications such as aerospace and flexible electronics. Summary of the Invention
[0003] In view of this, the purpose of the present invention is to provide a chain extender containing a dynamic imine bond and an imidazole ring, a preparation method and its application. The chain extender can form a metal coordination bond site by introducing the nitrogen atom in the imidazole ring into the elastomer, and the metal coordination effect can be formed between the molecular chains to further improve the strength and toughness of the elastomer.
[0004] To achieve the above objectives, the technical solutions of the present invention are as follows.
[0005] A chain extender containing a dynamic imine bond and an imidazole ring, the general structural formula of the chain extender is as follows:
[0006]
[0007] Wherein, R1 is a group containing an imidazole ring structure, and R2 is -(CH2) n -、 One or more of the following, wherein n is an integer from 1 to 4.
[0008] Preferably, R1 is One or more of the following.
[0009] A method for preparing a chain extender containing a dynamic imine bond and an imidazole ring according to the present invention comprises the following steps:
[0010] (1) mixing imidazole formaldehyde and an alcohol solvent, heating and stirring to dissolve, to obtain an imidazole formaldehyde solution;
[0011] mixing hydrazide and an alcohol-water mixed solvent, stirring and dissolving, to obtain a hydrazide solution;
[0012] (2) under nitrogen protection and stirring, the hydrazide solution is added dropwise to the imidazole formaldehyde solution, and the reaction is carried out at 60-80° C. for 7-12 hours; after the reaction is completed, the solid is collected, washed, and dried to obtain a chain extender containing a dynamic imine bond and an imidazole ring;
[0013] The reaction equation is as follows:
[0014]
[0015] In step (1), the structural formula of the hydrazide is Wherein, R2 is -(CH2) n -、
[0016] Preferably, in step (1), the imidazole carboxaldehyde is one or more of 2-imidazole carboxaldehyde, 4-imidazole carboxaldehyde, 5-methylimidazole-4-carboxaldehyde, 2-methylimidazole-4-carboxaldehyde, 2,5-dimethyl-1H-imidazole-4-carboxaldehyde, 2-ethyl-4-methylimidazole, 5-bromo-1H-imidazole-4-carboxaldehyde and 2-chloro-1H-imidazole-5-carboxaldehyde.
[0017] Preferably, in step (1), the alcohol solvent is methanol, ethanol or isopropanol; the alcohol-water mixed solvent is a mixed solvent of methanol and deionized water, and more preferably, the mass ratio of methanol to water is 1:1 to 3:1.
[0018] Preferably, in step (2), the molar ratio of hydrazide to imidazole carboxaldehyde is 1:2 to 1:5. More preferably, the molar ratio of hydrazide to imidazole carboxaldehyde is 1:2 to 1:3.
[0019] The invention discloses an application of a chain extender containing a dynamic imine bond and an imidazole ring. The chain extender is used for preparing polyurethane or epoxy materials.
[0020] Preferably, the preparation is carried out under 365nm ultraviolet light.
[0021] Beneficial effects
[0022] The present invention provides a chain extender containing a dynamic imine bond and an imidazole ring. Due to the imine bond, multiple hydrogen bonds and metal coordination supramolecular effects, the chain extender can achieve self-repair under certain conditions.
[0023] The present invention provides a preparation method of a chain extender containing a dynamic imine bond and an imidazole ring. Hydrazide is added during the synthesis process, and sites capable of forming multiple hydrogen bonds are introduced into the elastomer through the hydrazide fragments. Dense hydrogen bonds are introduced inside the material to ensure the mechanical strength of the material.
[0024] The present invention provides the use of a chain extender containing dynamic imine bonds and imidazole rings. Using this chain extender in polyurethane prepolymer chain extension yields a supramolecular polyurethane elastomer with synergistic effects of multiple hydrogen bonds and metal coordination bonds. This improves the mechanical strength and toughness of the material while also imparting supramolecular fluorescence-triggered luminescence, broadening the application of polyurethane materials. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 This is a physical picture of the white powdery solid in Example 1.
[0026] Figure 2 This is the Fourier transform infrared spectrum of the white powdery solid in Example 1.
[0027] Figure 3 This is the in-situ infrared spectrum of the epoxy resin in Example 3. DETAILED DESCRIPTION
[0028] The present invention will be further described in detail below with reference to specific embodiments.
[0029] Example 1
[0030] Step 1: Place 11.53 g (0.12 mol) of 4-imidazolecarboxaldehyde in a 500 mL three-necked flask, add 80 mL of methanol and stir to dissolve at 50°C;
[0031] Step 2: Weigh 10.45 g (0.06 mol) of adipic acid dihydrazide and dissolve it in 80 ml of a mixed solvent of methanol and deionized water (mass ratio of 2:1). Add it dropwise to the 4-imidazolecarboxaldehyde solution under nitrogen purge and stirring, and react at 60°C for 8 h.
[0032] Step 3: Filter the mixture, wash the solid with methanol and deionized water three times, and then dry it in a blast oven to obtain a white powdery solid. Figure 1 As shown, the crude yield was calculated to be 68%.
[0033] The Fourier infrared spectrum of the white powdery solid is as follows Figure 2 As shown, the successful synthesis of the chain extender was proved by the analysis of the groups.
[0034] Example 2
[0035] Step 1: Place 13.21 g (0.12 mol) of 5-methylimidazole-4-carboxaldehyde in a 500 mL three-necked flask, add 80 mL of anhydrous isopropyl alcohol and stir to dissolve at 50°C;
[0036] Step 2: Weigh 10.45 g (0.06 mol) of adipic acid dihydrazide and dissolve it in 80 ml of a mixed solvent of anhydrous isopropyl alcohol and deionized water (mass ratio of 2:1). Add it dropwise to the 5-methylimidazole-4-carboxaldehyde solution under nitrogen purge and stirring, and react at 60°C for 8 h.
[0037] Step 3: The mixture was filtered, and the solid was washed three times with anhydrous isopropyl alcohol and deionized water, respectively, and then dried in a forced air oven to obtain a white powdery solid. The crude yield was calculated to be 63%.
[0038] The Fourier transform infrared spectrum of the white powdery solid proved that the chain extender had been successfully synthesized.
[0039] The chain extender is used to prepare the polyurethane elastomer. The specific preparation method is as follows:
[0040] To prepare a polyurethane prepolymer, 200 g (0.1 mol) of dehydrated polytetrahydrofuran diol (PTMG 2000, water content ≤ 0.05%), 0.1 g of catalyst dibutyltin dilaurate, and 44.46 g (0.2 mol) of isophorone diisocyanate (IPDI) were added to a three-necked flask under nitrogen protection. The mixture was stirred at 80° C. for 3 h. The reaction was terminated when the -NCO content of the prepolymer reached the set value of 3.44%, thereby obtaining an isocyanate-terminated polyurethane prepolymer.
[0041] S1: Disperse 36.67 g of prepolymer and 4.86 g of chain extender in an N,N-dimethylformamide solution with a water content of less than 0.03%. Add the chain extender solution dropwise to the prepolymer solution under nitrogen atmosphere with stirring at 200 rpm and reaction at 80°C for 4 h to obtain a polyurethane polymer.
[0042] S2: Dissolve 2.67 g of zinc trifluoromethanesulfonate (Zn(OTf)2) in 50 ml of N,N-dimethylformamide solution, then add it to the polymer reacted in step S1 and stir evenly;
[0043] S3: The mixed solution obtained in step 2 is vacuum degassed and then poured into a glass mold, and dried at 80° C. under vacuum for 48 hours to obtain a polyurethane supramolecular elastomer with multiple hydrogen bonds and metal coordination effects.
[0044] The tensile strength of the polyurethane supramolecular elastomer was measured to be 43 mPa and the elongation at break was 643%.
[0045] Example 3
[0046] Step 1: Place 11.53 g (0.12 mol) of 4-imidazolecarboxaldehyde in a 500 mL three-necked flask, add 80 mL of anhydrous ethanol and stir to dissolve at 50°C;
[0047] Step 2: Weigh 7.93 g (0.06 mol) of malonic acid dihydrazide and dissolve it in 80 ml of a mixed solvent of ethanol and deionized water (mass ratio of 2:1). Add it dropwise to the 4-imidazolecarboxaldehyde solution under nitrogen purge and stirring, and react at 60°C for 8 h.
[0048] Step 3: The mixture was filtered, and the solid was washed three times with ethanol and deionized water, respectively, and then dried in a forced air oven to obtain a white powdery solid. The crude yield was calculated to be 67%.
[0049] The synthesized product is used for the preparation of epoxy resin. The specific preparation method is as follows:
[0050] 1 g of epoxy monomer and a stoichiometric amount of the synthesized compound were dissolved in 30 g of DMSO. Under a nitrogen atmosphere, the solution was heated to 110°C with continuous stirring and allowed to react for 5 hours. The temperature was then lowered to 80°C, and a DMSO solution of zinc trifluoromethanesulfonate was added to the mixture. After chelation for 2 hours, the system was cooled to room temperature, degassed using a vacuum oven, and the solvent was evaporated in a forced-air oven at 80°C. Residual solvent was removed under vacuum to obtain the epoxy network.
[0051] The measured tensile strength was 53 MPa and the elongation at break was 22%. In situ infrared spectroscopy was used to characterize the hydrogen bonding interactions of the epoxy network in the range of 30°C to 190°C. As the temperature increased, the broad peak formed by hydrogen bonding became narrower and weaker, indicating that hydrogen bonding gradually dissociated with increasing temperature.
[0052] In summary, the invention includes but is not limited to the above embodiments. Any equivalent replacement or partial improvement made under the spirit and principle of the present invention shall be deemed to be within the scope of protection of the present invention.
Claims
1. A chain extender containing a dynamic imine bond and an imidazole ring, characterized in that: The general structural formula of the chain extender is as follows: Wherein, R1 is a group containing an imidazole ring structure, and R2 is One or more of the following, wherein n is an integer from 1 to 4.
2. A chain extender containing a dynamic imine bond and an imidazole ring according to claim 1, characterized in that: R1 is One or more of the following.
3. A method for preparing a chain extender containing a dynamic imine bond and an imidazole ring according to claim 1 or 2, characterized in that: The method steps include: (1) mixing imidazole formaldehyde and an alcohol solvent, heating and stirring to dissolve, to obtain an imidazole formaldehyde solution; mixing hydrazide and an alcohol-water mixed solvent, stirring and dissolving, to obtain a hydrazide solution; (2) under nitrogen protection and stirring, the hydrazide solution is added dropwise to the imidazole formaldehyde solution, and the reaction is carried out at 60-80° C. for 7-12 hours; after the reaction is completed, the solid is collected, washed, and dried to obtain a chain extender containing a dynamic imine bond and an imidazole ring; The structural formula of the hydrazide is Among them, R2 is 4. The method for preparing a chain extender containing a dynamic imine bond and an imidazole ring according to claim 3, wherein: In step (1), the imidazole carboxaldehyde is one or more of 2-imidazole carboxaldehyde, 4-imidazole carboxaldehyde, 5-methylimidazole-4-carboxaldehyde, 2-methylimidazole-4-carboxaldehyde, 2,5-dimethyl-1H-imidazole-4-carboxaldehyde, 2-ethyl-4-methylimidazole, 5-bromo-1H-imidazole-4-carboxaldehyde and 2-chloro-1H-imidazole-5-carboxaldehyde.
5. The method for preparing a chain extender containing a dynamic imine bond and an imidazole ring according to claim 3, wherein: In step (1), the alcohol solvent is methanol, ethanol or isopropanol; and the alcohol-water mixed solvent is a mixed solvent of methanol and deionized water.
6. The method for preparing a chain extender containing a dynamic imine bond and an imidazole ring according to claim 5, wherein: The mass ratio of methanol to water is 1:1 to 3:
1.
7. The method for preparing a chain extender containing a dynamic imine bond and an imidazole ring according to claim 3, wherein: In step (2), the molar ratio of hydrazide to imidazole formaldehyde is 1:2 to 1:
5.
8. The method for preparing a chain extender containing a dynamic imine bond and an imidazole ring according to claim 7, wherein: The molar ratio of the hydrazide to imidazole formaldehyde is 1:2 to 1:
3.
9. Use of a chain extender containing a dynamic imine bond and an imidazole ring as claimed in claim 1 or 2, characterized in that: The chain extender is used for the preparation of polyurethane or epoxy materials.
10. Use of a chain extender containing a dynamic imine bond and an imidazole ring according to claim 9, characterized in that: The preparation was carried out under 365 nm ultraviolet light.