Environment-friendly high polymer material capable of regulating and controlling dynamic network and preparation and closed-loop recovery method of environment-friendly high polymer material

Abstract

The invention belongs to the field of polymer materials, and provides an environment-friendly high polymer material capable of regulating and controlling a dynamic network and a preparation and closed-loop recovery method thereof, and the preparation and closed-loop recovery method comprises the following steps: carrying out photopolymerization reaction on acetoacetic acid alkene and mercaptans with different functionalities in a solvent to obtain a polyfunctional acetoacetic ester polymer; carrying out a cross-linking reaction on the acetoacetate polymer and a polyamine monomer in a solvent to obtain a prepolymer; and curing the prepolymer to obtain a Vitrimer polymer film, and annealing to obtain the Vitrimer polymer film. Acetoacetate polymers with different branching conditions are prepared through an alkene click reaction, the material is endowed with different network structures, and dynamic and mechanical properties of the network are regulated and controlled by regulating the network and cross-linking points; and meanwhile, the introduction of the vinyl amine ester bond to the polymer network provides possibility for closed-loop recovery upgrading of the polymer network.

Description

Technical Field

[0001] The present invention belongs to the field of polymer materials, and relates to an environmentally friendly polymer material with adjustable dynamic network and a preparation and closed-loop recycling method thereof, and in particular to a closed-loop recycling material with high mechanical properties, recyclability and degradability. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] With the widespread dissemination of the concept of sustainable development and increasingly stringent environmental regulations, the demand for recyclable and degradable high-performance polymers in the field of materials science is increasing. However, traditional thermosetting polymers have excellent strength and durability in mechanical properties due to their highly cross-linked permanent network structure, but due to these irreversible cross-linking points, they are difficult to recycle after use, causing serious pollution problems to the environment.

[0004] In recent years, a class of polymer materials with dynamic reversible cross-linked network characteristics has gradually emerged. Under specific external conditions (such as heat or catalysts), the dynamic chemical bonds contained in such materials can break and reorganize, so that the materials have both processability and repairability while maintaining high mechanical properties, providing a new technical path for the closed-loop recycling of high-performance materials. However, the existing dynamic reversible cross-linked network materials still have certain balancing problems between processing and recycling and mechanical properties: when the cross-linking strength is high, the mechanical properties can be guaranteed, but the dynamic cross-linking reaction rate is usually slow, resulting in inefficient recycling and reprocessing processes; when the recycling efficiency is improved by reducing the cross-linking strength, the overall mechanical properties of the material are difficult to meet the application requirements. In addition, some current methods often only regulate the spacing between cross-linking points by increasing or decreasing the molecular weight to achieve the regulation of the dynamic network. Although it can affect the relaxation properties of the network to a certain extent, it has limited effect on the activation energy of the dynamic bonds, because the topological structure of the dynamic network is not essentially changed, and it is impossible to significantly improve the processing performance while maintaining high mechanical properties. At the same time, in a large number of industrial applications, efficient synthesis and large-scale production of materials are also crucial. If the reaction conditions are too harsh (such as high temperature, high pressure or extreme acidity and alkalinity), it will not only increase production costs and energy consumption, but also increase safety risks, which is not conducive to large-scale promotion. Summary of the invention

[0005] In order to solve the above problems, the present invention provides an environmentally friendly polymer material with adjustable dynamic network and its preparation and closed-loop recycling method, and prepares acetoacetate polymers with different branch structures through thiol-ene click reaction to adjust the cross-linking nodes and branch number in the network, thereby giving the material an adjustable network topology and effectively regulating its dynamic and mechanical properties. At the same time, the introduction of vinylamine ester bonds in the polymer network provides a feasible way to achieve closed-loop recycling of the material.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] The first aspect of the present invention provides a method for preparing an environmentally friendly polymer material with a controllable dynamic network, comprising:

[0008] Acetoacetate olefin and thiols with different functionalities are photopolymerized in a solvent to obtain multifunctional acetoacetate polymers;

[0009] Cross-linking the acetoacetate polymer and the polyamine monomer in a solvent to obtain a prepolymer;

[0010] After the prepolymer is solidified, annealing treatment is performed to obtain the dynamic network polymer material film.

[0011] The thiol-ene click reaction is an efficient, fast, and highly selective chemical reaction for side reactions, which is very suitable for the synthesis of polymer materials with dynamic network characteristics. Its main advantages include: mild reaction conditions: the thiol-ene reaction can be carried out at a relatively low temperature or under catalytic conditions, and does not require high pressure or strong acid or base environment, which is suitable for large-scale production. High selectivity: the thiol-ene click reaction can generate a stable covalent bond structure with very few side reactions, ensuring the stability of the material structure and the uniformity of the cross-linked network. Therefore, the ene click reaction can effectively prepare the ideal acetoacetate monomer.

[0012] Based on the above principle, the present invention prepares acetoacetate polymers by carefully designing an ene click reaction system, and introduces a reversible vinylamine ester bond to obtain a cross-linked polymer with different mechanical properties and thermodynamic properties. The introduction of a multifunctional monomer not only makes the mechanical properties of the cross-linked network adjustable, but also provides conditions for the closed-loop recycling and upgrading of the polymer, ensuring that the material has both high performance and environmental protection characteristics, thereby meeting the needs of various application scenarios for recyclable, degradable and high-performance polymer materials. In some embodiments, the acetoacetate ene is ethylene glycol methacrylate or allyl acetoacetate.

[0013] In some embodiments, the thiol is selected from one of bis(3-mercaptopropionic acid)ethylene glycol, trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionic acid), ethanedithiol, and hexanedithiol.

[0014] In some embodiments, the molar ratio of acetoacetate to thiol is 1:1-4.

[0015] In some embodiments, the initiator of the photopolymerization reaction is 2-hydroxy-2-methylpropiophenone or phenyldibenzothiophene, and the added amount is 0.4%-0.6% of the total weight of the monomers.

[0016] In some embodiments, the polyamine monomer is selected from at least one of isophoronediamine, hexamethylenediamine, and tris(2-aminoethyl)amine.

[0017] In some embodiments, the molar ratio of the acetoacetate polymer to the amine group is 1:1 to 1.5; the dynamic properties of the network can be adjusted according to the ratio provided by the amine group.

[0018] In some embodiments, the annealing temperature is 120° C.-130° C., and the time is 6 h-8 h.

[0019] More specifically, they include:

[0020] The first step: add acetoacetate olefin and thiol with a molar ratio of C=C:SH group of 1:1 into a flask equipped with a magnetic stirrer, and then add 0.5-2wt% of photoinitiator 2-hydroxy-2-methylpropiophenone, stir at 20-60°C, and irradiate the reactants with a UV lamp (365nm, 1200uw / cm2) for 24 hours to obtain the product acetoacetate monomer.

[0021] In the second step, acetoacetate monomer and polyamine monomer in a molar ratio of 1:1.2 to 1:1.5 are added into a 100 mL three-necked flask equipped with a reflux condenser, an electric stirrer, and a thermometer, 20 ml of DMF is added, and the mixture is reacted at 20 to 50 ° C for 4 hours, and then cooled to ambient temperature to obtain a prepolymer.

[0022] In the third step, the prepolymer is transferred to a polytetrafluoroethylene mold, placed in an 80°C oven for 24 hours to remove DMF, and then cured in an oven at 120°C for 4 hours to obtain a dynamic network polymer film containing vinylamine ester bonds. To ensure that the film has good mechanical properties and network structure, an annealing treatment can be performed at 120°C for 6-8 hours.

[0023] The fourth step is the recovery and upgrading of the polymer. The obtained polymer is chopped and put into a three-necked flask, and a 0.1 mol / L mixed solution of hydrochloric acid and tetrahydrofuran is added. The solution containing acetoacetate and amine salt are filtered to obtain the acetoacetate polymer monomer. The acetoacetate solution is neutralized and purified to obtain the acetoacetate polymer monomer. The amine salt can be reduced to amine using a methanol solution of KOH.

[0024] The second aspect of the present invention provides an environmentally friendly polymer material with a controllable dynamic network prepared by the above method.

[0025] The present invention aims to obtain an environmentally friendly polymer material with high mechanical properties and excellent recycling and reuse capabilities by introducing a dynamic cross-linked network structure that is easy to regulate, and a gentle and efficient click chemistry reaction path. At the material design level, by rationally selecting and adjusting the type and quantity of the thiol-ene reaction system and the reversible cross-linking unit, the activation energy of the dynamic bond can be effectively reduced, and the network topology can be accurately regulated, so as to achieve a good balance between closed-loop recycling and adjustable mechanical properties. At the same time, the preparation process conditions of the present invention are mild and the steps are simplified, which is conducive to industrial production. It can provide high value-added and environmentally sustainable polymer materials for multiple fields under the premise of reducing resource and energy consumption. Through the above-mentioned technical means and ideas, a feasible and efficient solution will be provided to solve the problem that the current thermosetting polymer materials are difficult to recycle, and new ideas and assistance will be provided for the development of sustainable materials and circular economy.

[0026] The third aspect of the present invention provides a closed-loop recycling method for the above-mentioned environmentally friendly polymer material with adjustable dynamic network, comprising:

[0027] After the polymer material containing vinylamine ester bonds is chopped up, a 0.1-0.15 mol / L hydrochloric acid tetrahydrofuran solution is added, and the mixture is filtered to obtain a solution containing acetoacetate and an amine salt;

[0028] neutralizing and purifying the solution containing acetoacetate to obtain acetoacetate polymer;

[0029] The amine salt is reduced to amine using a methanol solution of KOH to obtain the product.

[0030] The fourth aspect of the present invention provides the application of the above-mentioned environmentally friendly polymer material with adjustable dynamic network in the construction industry, transportation packaging, optics and aerospace fields.

[0031] Beneficial effects of the present invention

[0032] (1) Based on the dynamic reversible properties of the thiol-ene click reaction and the vinylamine ester bond, the present invention can achieve the breaking and recombination of crosslinking points under appropriate external conditions, allowing closed-loop recycling of materials. Compared with traditional non-recyclable thermosetting materials, the materials of the present invention can effectively reduce resource consumption and waste generation, and have significant environmental advantages.

[0033] (2) The preparation method of the present invention allows the network topology to be changed by adjusting the functionality of thiols and amines, and can control two different types of cross-linking nodes and the number of branches of multiple cross-linking points, so as to flexibly adjust the dynamic performance, dynamic bond activation energy, mechanical properties and repairability of the material to meet the specific needs of different applications. The flexibility of the formula design makes the material highly adaptable, and the characteristics of the material can be adjusted according to the needs of different fields, and it is widely used in multiple industries such as construction, packaging, medical treatment, and electronics. The preparation method of the present invention can change the network topology by adjusting the functionality of thiols and amines, so as to flexibly control two different types of cross-linking nodes and the number of branches of multiple cross-linking points. Thereby, the dynamic performance, dynamic bond activation energy, mechanical properties and repairability of the material can be further adjusted to meet the specific needs of multiple application scenarios. Since the formula design has high flexibility, the material can be well applied in multiple industries such as construction, packaging, medical treatment, and electronics, and has strong adaptability.

[0034] (3) The thiol-ene click reaction has mild reaction conditions and does not require harsh conditions such as strong acid, strong base or high pressure, which is convenient for large-scale production and reduces energy consumption and safety risks in the production process. The preparation process of the material of the present invention is simple and low in cost, suitable for industrial application, and can be quickly promoted on existing production facilities to promote the market application of sustainable and high-performance materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings constituting a part of the present invention are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their description are only used to explain the present invention and do not constitute any improper limitation to the present invention.

[0036] Figure 1 This is the H NMR spectrum of the trifunctional acetoacetate monomer prepared in Example 1 of the present invention.

[0037] Figure 2 Schematic diagram of closed-loop recovery of the dynamic network polymer material containing vinylamine ester bonds prepared in Example 1 of the present invention.

[0038] Figure 3 This is a comparison chart of the mechanical properties of the dynamic network polymer material containing vinylamine ester bonds prepared in Example 1 of the present invention before and after solvent recovery. DETAILED DESCRIPTION

[0039] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0040] The present invention will be further described in detail below in conjunction with specific embodiments. It should be noted that the specific embodiments are intended to explain the present invention rather than to limit it.

[0041] Embodiment 1:

[0042] first step:

[0043] In a flask equipped with a magnetic stirrer, add allyl acetoacetate and trimethylolpropane tris(3-mercaptopropionate) in a molar ratio of C=C:SH groups of 1:1, and then add 0.5wt% of the total weight of the photoinitiator 2-hydroxy-2-methylpropiophenone. Stir at 20°C and use a wavelength of 365nm and an intensity of about 1200μW / cm 2 The product acetoacetate trimer was obtained by irradiating with UV light for 24 hours.

[0044] Step 2:

[0045] Take acetoacetate trimer and tri(2-aminoethyl)amine (TREN) in a molar ratio of 1:1.2, add them into a 100mL three-necked flask equipped with a reflux condenser, an electric stirrer and a thermometer, and add 20mL of DMF solvent, react at 20°C for 4 hours; then cool to room temperature to obtain a prepolymer.

[0046] Step 3:

[0047] The obtained prepolymer was transferred to a polytetrafluoroethylene mold, placed in an oven at 80°C for 24 hours to remove DMF, and then cured in an oven at 120°C for 4 hours to obtain a recyclable dynamic network polymer film containing vinylamine ester bonds. To further ensure the performance of the polymer, an annealing treatment can be performed at 120°C for 6 hours.

[0048] Step 4:

[0049] Cut the obtained film into pieces and put it into a three-necked flask, add a sufficient amount of 0.1 mol / L hydrochloric acid in tetrahydrofuran solution, and let it stand or stir at room temperature for 6 hours. At this time, TREN will react with hydrochloric acid to form an insoluble salt (such as Figure 2 A white precipitate appears. The acetoacetate-containing solution and the amine salt (such as Figure 2 (III, VI).

[0050] The obtained solution containing acetoacetate monomer or acetoacetate polymer can be neutralized with 0.1 mol / L NaHCO3 / NaCl solution with a molar ratio of 1:1, and then purified by distillation to recover the acetoacetate monomer or acetoacetate polymer. The obtained TREN·HCl insoluble salt can be reduced to TREN by adding 0.1 mol / L KOH methanol solution, and pure TREN can be obtained by distillation. The recovered monomer can directly react with the acetoacetate polymer to prepare a dynamic network polymer material containing vinylamine ester bonds again.

[0051] like Figure 3 As shown in FIG. 1 , it is a comparison diagram of the mechanical properties of the material prepared for the first time (Original), the material prepared again after the first recycling (recycle1), and the material prepared again after the second recycling (recycle2) in this embodiment. Figure 3 It can be seen that the dynamic network material containing vinylamine ester bonds prepared by the present invention (ie, the environmentally friendly polymer material with adjustable dynamic network) has a high recycling efficiency while maintaining high mechanical properties.

[0052] Embodiment 2:

[0053] first step:

[0054] In a flask equipped with a magnetic stirrer, ethylene bis(3-mercaptopropionic acid) ester and allyl acetoacetate were added in a molar ratio of 1:2, and then 0.5 wt% of the total weight of the photoinitiator 2-hydroxy-2-methylpropiophenone was added. Stirring was carried out at room temperature with a wavelength of 365 nm and an intensity of 1200 μW / cm 2 Irradiate with UV light for 48 hours to obtain acetoacetate dimer.

[0055] Step 2:

[0056] Acetoacetate dimer and isophorone diamine (IPDA) in a molar ratio of 1:1.2 were added with 20 mL of DMF solution and reacted at 40° C. for 5 hours to obtain a prepolymer.

[0057] Step 3:

[0058] The obtained prepolymer was transferred to a polytetrafluoroethylene mold, baked at 80°C for 24 hours, and then cured at 120°C for 4 hours to obtain a dynamic network polymer film containing vinylamine ester bonds, and annealed (120°C for 6 hours).

[0059] Step 4:

[0060] After the obtained film is chopped, 0.1 mol / L tetrahydrofuran hydrochloric acid solution is added and filtered to obtain a solution containing acetoacetate, and the acetoacetate monomer (acetoacetate dimer) is recovered after neutralization and purification. Amine salt is reduced with KOH methanol solution to obtain new amine monomer, completing the recovery of raw material components.

[0061] Embodiment 3:

[0062] first step:

[0063] Trimethylolpropane tris(3-mercaptopropionate) and ethylene glycol acetoacetate methacrylate were added to a flask in a molar ratio of 1:3, and 0.6 wt% of the total weight of the photoinitiator phenyl dibenzothiophene was added. The mixture was stirred at 30 °C and the wavelength was 365 nm and the intensity was 1000 μW / cm 2 After irradiation with UV light for 72 hours, acetoacetate trimer was obtained.

[0064] Step 2:

[0065] The acetoacetate trimer was reacted with hexamethylenediamine (molar ratio 1:1.5), 20 mL of N,N-dimethylacetamide (DMA) solution was added, and the mixture was reacted at 50° C. for 5 hours to obtain a prepolymer.

[0066] Step 3:

[0067] The prepolymer was transferred to a polytetrafluoroethylene mold, baked at 80°C for 24 hours, and then cured at 120°C for 4 hours to obtain a dynamic network polymer film containing vinylamine ester bonds, and annealed (120°C for 6 hours).

[0068] Step 4:

[0069] The solidified polymer is chopped up, placed in a tetrahydrofuran hydrochloride solution and filtered to obtain a solution containing acetoacetate; after the solution is neutralized and purified, the acetoacetate monomer and acetoacetate polymer can be recovered, and the amine salt can be reduced to the amine monomer to achieve recycling.

[0070] Embodiment 4:

[0071] first step:

[0072] In a flask, pentaerythritol tetrakis(3-mercaptopropionic acid) ester and allyl acetoacetate were added in a molar ratio of 1:4, and phenyldibenzothiophene, a photoinitiator, was added in an amount of 0.4 wt% of the total weight of the two. The mixture was stirred at 25 °C and the wavelength was 365 nm and the intensity was 1500 μW / cm 2 After irradiation with UV light for 36 hours, acetoacetate tetramer was obtained.

[0073] Step 2:

[0074] Acetoacetate tetramer and tri(2-aminoethyl)amine in a molar ratio of 1:1.3 were reacted, 20 mL of DMF solution was added, and the mixture was reacted at 60° C. for 4 hours to obtain a prepolymer.

[0075] Step 3:

[0076] The prepolymer was transferred to a polytetrafluoroethylene mold, baked at 80°C for 24 hours, and then cured at 120°C for 4 hours to obtain a dynamic network polymer film containing vinylamine ester bonds, and then annealed (treated at 120°C for 6 hours).

[0077] Step 4:

[0078] After the film is chopped, a tetrahydrofuran hydrochloride solution is added and filtered to obtain a solution containing acetoacetate; and then a KOH methanol solution is used to reduce the amine salt to achieve amine monomer recovery.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing an environmentally friendly polymer material with adjustable dynamic network, characterized in that: include: Acetoacetate olefin and thiols with different functionalities are photopolymerized in a solvent to obtain multifunctional acetoacetate polymers; The acetoacetate polymer and the polyamine monomer are cross-linked in a solvent to obtain a prepolymer; the prepolymer is solidified to obtain an environmentally friendly polymer film with a controllable dynamic network, and annealing is performed to obtain the film.

2. The method for preparing an environmentally friendly polymer material with a controllable dynamic network as claimed in claim 1, characterized in that: The acetoacetate is ethylene glycol methacrylate or allyl acetoacetate.

3. The method for preparing an environmentally friendly polymer material with a controllable dynamic network as claimed in claim 1, characterized in that: The thiol is selected from one of bis(3-mercaptopropionic acid)ethylene glycol, trimethylolpropane tris(3-mercaptopropionic acid), pentaerythritol tetrakis(3-mercaptopropionic acid), ethanedithiol or hexanedithiol.

4. The method for preparing an environmentally friendly polymer material with a controllable dynamic network as claimed in claim 1, characterized in that: The molar ratio of acetoacetate to mercaptan is 1:1-4.

5. The method for preparing an environmentally friendly polymer material with a controllable dynamic network as claimed in claim 1, characterized in that: The initiator of the photopolymerization reaction is 2-hydroxy-2-methylpropiophenone or phenyldibenzothiophene, and the added amount is 0.4% to 0.6% of the total weight of the monomers.

6. The method for preparing an environmentally friendly polymer material with a controllable dynamic network as claimed in claim 1, characterized in that: The polyamine monomer is selected from at least one of isophoronediamine, hexamethylenediamine or tris(2-aminoethyl)amine.

7. The method for preparing an environmentally friendly polymer material with a controllable dynamic network as claimed in claim 1, characterized in that: The molar ratio of the acetoacetate polymer to the amine group is 1:1-1.5; or, the annealing temperature is 120° C. and the time is 6-8 hours.

8. An environmentally friendly polymer material with a controllable dynamic network prepared by the method according to any one of claims 1 to 7.

9. A closed-loop recycling method for environmentally friendly polymer materials with adjustable dynamic networks as claimed in claim 8, characterized in that: include: After the environmentally friendly polymer material with adjustable dynamic network is chopped up, a 0.1-0.15 mol / L hydrochloric acid tetrahydrofuran solution is added, and the solution containing acetoacetate and amine salt is obtained by filtering; neutralizing and purifying the solution containing acetoacetate to obtain acetoacetate polymer; The amine salt is reduced to amine using a methanol solution of KOH to obtain the product.

10. Application of the environmentally friendly polymer material with adjustable dynamic network as claimed in claim 8 in the construction industry, transportation packaging, optics or aerospace fields.

Images