Thermosetting polymer containing dynamic covalent bonds and preparation thereof

Abstract

The invention discloses a dynamic acetal amine bond-containing polymer prepared from diamine containing a naphthalimide derivative and a preparation method of the dynamic acetal amine bond-containing polymer, and the dynamic acetal amine bond-containing polymer is prepared by reacting paraformaldehyde with diamine containing the naphthalimide derivative in a mixed system of N-methyl pyrrolidone and water. The dynamic acetal amine bond-containing polymer prepared by the invention has good self-healing ability, can stably exist in most organic solvents, and can be degraded into an initial raw material under an acidic condition.

Description

Technical Field

[0001] The invention belongs to the field of polymer materials and relates to a naphthalene diimide-containing polymer and a preparation method thereof. Background Art

[0002] Polymer materials are an indispensable material in today's social production and life. According to their different thermal behaviors, they are divided into thermoplastic polymers and thermosetting polymers. Among them, thermoplastic polymers have low hardness and poor high temperature resistance. Common thermoplastic polymers will undergo severe deformation at around 80°C, so their application range is greatly limited. In contrast, thermosetting polymers have attracted much attention due to their good thermal stability and chemical stability. However, the cross-linking and curing of thermosetting polymers is a non-reversible process. Once heated and cured, it is difficult to reprocess and recycle, which greatly wastes resources and pollutes the environment. At the same time, it does not have self-repairing ability, and it is difficult to detect and timely discover local damage and microcracks, which increases safety hazards and maintenance costs. Therefore, giving thermosetting polymers the properties of remodelability, easy recycling, and self-repair is of far-reaching significance for saving energy, protecting the environment, and achieving sustainable development of the national economy.

[0003] In order to solve this problem, researchers introduced dynamic covalent bonds into the preparation of thermosetting polymers. Dynamic covalent bonds are a type of covalent bonds with reversible properties. They can break and reorganize under certain external conditions, thereby achieving the reuse and self-repair of thermosetting polymers. Dynamic aminal bonds are a typical dynamic covalent bond formed by the polycondensation reaction of diamino groups and polyformaldehyde.

[0004] In 2014, García et al. first proposed to use diamines and polyformaldehyde to react in a glove box for 24 hours to obtain a polymer containing dynamic aminal bonds, and the resulting polymer has a high glass transition temperature. In 2019, Zhang et al. reported that 4,4′-diaminodiphenylmethane was reacted with polyformaldehyde in a micro-internal mixer to obtain a white fine solid, and then the powder was prepared by a high-speed crusher. The molded solid material was hot-pressed in an aluminum mold of a specific shape to prepare such a polymer. However, the above two reaction conditions are relatively harsh, and the required experimental equipment is relatively expensive, which is difficult to achieve in general laboratories. Kaminker et al. used diamines and polyformaldehyde in the absence of solvents to synthesize polymers containing dynamic aminal bonds, which have a high Young's modulus and excellent solvent resistance, but only liquid or low-melting-point diamines can be used, which is very limited and cannot be used in practice.

[0005] So far, although researchers have conducted some research on polymers containing dynamic aminal bonds and have made valuable progress, the construction process is limited to the polycondensation of aliphatic diamines, phenylenediamine and polyformaldehyde. At present, there are still great problems and challenges, mainly including: 1. The reaction conditions are relatively harsh, the required experimental equipment is relatively expensive, and it is difficult for general laboratories to meet the conditions; 2. The research on polymer materials constructed based on this method is still in the initial stage, and the research is mainly focused on the preparation of gel soft materials, which limits its industrial promotion and application.

[0006] Therefore, under simple experimental conditions, the preparation of polymers containing dynamic acetal amine bonds using complex diamine compounds with functional groups can achieve the preparation of special functional materials with excellent mechanical properties, which is of great significance and facilitates industrialization. Summary of the invention

[0007] The purpose of the present invention is to prepare a polymer containing a dynamic aminal bond by using a diamine containing an imide derivative, which is a polymer represented by the following structural formula: .

[0008] Providing a method for preparing the polymer is another object of the present invention.

[0009] The polymer containing dynamic aminal bonds of the present invention is prepared by using naphthalene diimide derivative diamine and polyformaldehyde under the condition of N-methylpyrrolidone as solvent.

[0010] 1) Dissolve 4,4'-diaminodiphenyl ether and 1,4,5,8-naphthalenetetracarboxylic dianhydride in N-methylpyrrolidone to prepare a diamine containing a naphthalene diimide derivative, chemical formula C 38 H 24 N4O6, its structural formula is as follows:

[0011] 2) Paraformaldehyde and a diamine containing a naphthalene diimide derivative are dissolved in N-methylpyrrolidone and water to prepare a polymer containing a dynamic aminal bond.

[0012] A more specific preparation method of the compound of the present invention is as follows:

[0013] 1) Specifically, 4,4'-diaminodiphenyl ether is dissolved in N-methylpyrrolidone, and then 1,4,5,8-naphthalenetetracarboxylic dianhydride is added to the above solution, and stirred at warm temperature for 20 to 30 hours. After the reaction is completed, deionized water is added, and the diamine containing the naphthalene diimide derivative is obtained by filtration;

[0014] 2) Take paraformaldehyde, add N-methylpyrrolidone and water and stir to obtain a clear transparent solution. Add the diamine containing naphthalene diimide derivative obtained in the previous step, react for 30 to 100 minutes, and dry in a vacuum oven to obtain a polymer containing dynamic aminal bonds.

[0015] Wherein, in the step 1), the molar ratio of 4,4'-diaminodiphenyl ether to naphthalene-1,4,5,8-tetracarboxylic dianhydride is preferably 1:0.9-1.3, and the total amount of the reactants fed to the N-methylpyrrolidone solvent is 0.5-3 g total amount of feed / 11 mL of solvent.

[0016] Wherein, in the step 2), the molar ratio of the diamine of the naphthalene diimide derivative to the polyformaldehyde substance is 1:1.5-3, and the molar ratio of the total amount of the reactants to the N-methylpyrrolidone solvent is 0.5-3g total amount of the reactants / 11mL of the solvent.

[0017] The present invention finds that the polymer can self-heal at room temperature without being affected by external forces after being left to stand for a period of time.

[0018] Specifically, the polymer is cut into squares with a side length of 2 to 5 cm, cut in the middle, and left to stand at 20 to 50° C. for 5 to 10 days without any external interference.

[0019] Furthermore, in the solvent resistance method of the above-mentioned compound, the polymer is immersed in solvents of different polarities, and the mass change before and after immersion is weighed after 5 to 10 days.

[0020] Furthermore, in a recycling method of the above polymer, the above polymer is soaked in a strong acid solution, then neutralized with an alkaline solution, precipitated, filtered, washed with water, and dried, and the obtained substance is compared with a diamine containing a naphthalene diimide derivative. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is the infrared spectrum of the polymer containing dynamic aminal bonds prepared in this example.

[0022] Figure 2 is the hydrogen nuclear magnetic resonance spectrum of the polymer containing dynamic aminal bonds prepared in this example.

[0023] Figure 3 This is a self-healing test diagram of the polymer containing dynamic aminal bonds prepared in this embodiment.

[0024] Figure 4 This is a test chart of the solvent resistance of the polymer containing dynamic aminal bonds prepared in this example. DETAILED DESCRIPTION

[0025] The following embodiments are only preferred technical solutions of the present invention and are not intended to limit the present invention in any way. For those skilled in the art, the present invention may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should all be included in the protection scope of the present invention. Example

[0026] Example 1

[0027] 1) Weigh 4,4'-diaminodiphenyl ether in a round-bottom flask, dissolve it in an appropriate amount of N-methylpyrrolidone, and then drop triethylamine. Dissolve 1,4,5,8-naphthalenetetracarboxylic dianhydride in N-methylpyrrolidone and drop it into the above solution at 80°C, with a molar ratio of 1:1. After all the additions are completed, stir at a constant temperature for 24 hours. After the reaction is completed, add the solution into deionized water, and then recrystallize it with deionized water several times to obtain a diamine containing a naphthalene diimide derivative.

[0028] 2) Weigh paraformaldehyde into a round-bottom flask, add 10 mL of N-methylpyrrolidone and 1 mL of water, stir at 80°C for 2 h, and obtain a clear and transparent solution. Add the diamine of the naphthalene diimide derivative obtained in the previous step to the solution at a molar ratio of 1:2.5, react at 50°C for 60 minutes, pour it into a polytetrafluoroethylene mold, and dry it in a vacuum oven at 50°C for 48 h to obtain a polymer containing dynamic aminal bonds.

[0029] Figure 1 is the infrared spectrum of the polymer containing dynamic aminal bonds prepared in this example.

[0030] Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of the polymer containing dynamic aminal bonds prepared in this example. In the spectrum, * indicates a solvent peak, and all characteristic peaks thereof are clearly assigned. There are almost no impurity peaks in the spectrum, which proves that the prepared compound has a high purity.

[0031] Combination Figure 1 , 2 , which can prove that the target product was successfully synthesized in this example.

[0032] The polymer containing dynamic aminal bonds can self-heal at room temperature without any external intervention, such as Figure 3 shown.

[0033] The polymer containing dynamic aminal bonds has no obvious changes in appearance and quality after being immersed in solvents of different polarities (cyclohexane, toluene, ethyl acetate, tetrahydrofuran, 1,4-dioxane, methanol, N,N-dimethylformamide, water, N-methylpyrrolidone) for 7 days. Figure 4 , group a is the initial state, and group b is the state after 7 days.

[0034] Example 2

[0035] 1) Weigh 4,4'-diaminodiphenyl ether in a round-bottom flask, dissolve it in an appropriate amount of N-methylpyrrolidone, and then drop triethylamine. Dissolve 1,4,5,8-naphthalenetetracarboxylic dianhydride in N-methylpyrrolidone and drop it into the above solution at 85°C, with a molar ratio of 1:1.2. After all the additions are completed, stir at a constant temperature for 20 hours. After the reaction is completed, add the solution into deionized water, and then recrystallize it with deionized water several times to obtain a diamine containing a naphthalene diimide derivative.

[0036] 2) Weigh paraformaldehyde into a round-bottom flask, add 10 mL of N-methylpyrrolidone and 1 mL of water, stir at 80°C for 2 h, and obtain a clear and transparent solution. Add the diamine of the naphthalene diimide derivative obtained in the previous step to the solution at a molar ratio of 1:2.0, react at 55°C for 70 minutes, pour it into a polytetrafluoroethylene mold, and dry it in a vacuum oven at 50°C for 48 h to obtain a polymer containing a dynamic aminal bond.

[0037] Example 3

[0038] 1) Weigh 4,4'-diaminodiphenyl ether in a round-bottom flask, dissolve it in an appropriate amount of N-methylpyrrolidone, and then drop triethylamine. Dissolve 1,4,5,8-naphthalenetetracarboxylic dianhydride in N-methylpyrrolidone and drop it into the above solution at 75°C, with a molar ratio of 1:1.3. After all the additions are completed, stir at a constant temperature for 26 hours. After the reaction is completed, add the solution into deionized water, and then recrystallize it with deionized water several times to obtain a diamine containing a naphthalene diimide derivative.

[0039] 2) Weigh paraformaldehyde into a round-bottom flask, add 10 mL of N-methylpyrrolidone and 1 mL of water, stir at 80°C for 2 h, and obtain a clear and transparent solution. Add the diamine of the naphthalene diimide derivative obtained in the previous step to the solution at a molar ratio of 1:2.2, react at 55°C for 70 minutes, pour the solution into a polytetrafluoroethylene mold, and dry it in a vacuum oven at 50°C for 48 h to obtain a polymer containing a dynamic aminal bond.

Claims

1. A polymer containing a dynamic aminal bond prepared from a diamine containing a naphthalene diimide derivative, having the structural formula shown below: 。 2. The method for preparing the polymer according to claim 1, comprising the steps of: 1) dissolving 4,4'-diaminodiphenyl ether and 1,4,5,8-naphthalenetetracarboxylic dianhydride in N-methylpyrrolidone to prepare a diamine containing a naphthalene diimide derivative; 2) Take paraformaldehyde, add N-methylpyrrolidone and water and stir to obtain a clear transparent solution. Add the diamine containing naphthalene diimide derivative obtained in the previous step to the solution and react for 20 to 100 minutes to obtain a polymer containing dynamic aminal bonds.

3. The method for preparing a diamine containing a naphthalene diimide derivative according to claim 2, characterized in that The molar ratio of the 4,4'-diaminodiphenyl ether to naphthalene-1,4,5,8-tetracarboxylic dianhydride is 1:0.9-1.

3.

4. The method for preparing a diamine containing a naphthalene diimide derivative according to claim 2, characterized in that In the step, the method for separating the diamine containing the naphthalene diimide derivative from the reaction product is to recrystallize the reaction product twice with deionized water and vacuum dry it to obtain the polymer containing the dynamic aminal bond.

5. The method for preparing a naphthalene diimide-containing polymer according to claim 2, characterized in that The molar ratio of the diamine containing the naphthalene diimide derivative to the polyformaldehyde is 1:1.5-3.

6. The method for preparing a naphthalene diimide-containing polymer according to claim 2, characterized in that The volume ratio of water to N-methylpyrrolidone is 1:8-20.

7. The method for preparing a naphthalene diimide-containing polymer according to claim 2, characterized in that The temperature of the reaction of the diamine containing the naphthalene diimide derivative and the polyformaldehyde is 30 to 80° C. and the time is 20 to 100 minutes.

8. Use of the polymer containing dynamic aminal bonds according to claim 1 as a membrane material.

9. The method for recycling a polymer containing a dynamic aminal bond according to claim 1, characterized in that: The polymer is soaked in a strong acid solution, and then neutralized with an alkaline solution, precipitated, filtered, washed with water, and dried to obtain the diamine containing the naphthalene diimide derivative as the initial raw material.

Images