Preparation and recycling method of light-controlled reversible coordination cross-linked polyacrylonitrile
By combining photocontrolled reversible coordination ruthenium crosslinking agent with polyacrylonitrile, reversible crosslinking polyacrylonitrile polymer materials are prepared, which solves the problem of difficult recycling of industrial polymer materials and achieves multiple recycling of materials and improves performance.
Patent Information
- Application Number
- CN202210806008.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-07-08
- Publication Date
- 2025-08-12
- Estimated Expiration
- 2042-07-08
AI Technical Summary
Due to its insoluble and non-melting properties, polymer materials produced in the industry are difficult to recycle, resulting in environmental pollution and waste of resources. The existing reversible crosslinked polymer materials are limited in the application of industrial production.
The photo-controlled reversible coordination ruthenium crosslinking agent and polyacrylonitrile were dissolved in N,N-dimethylformamide, and the reversible crosslinked polyacrylonitrile polymer material was prepared through light and heating conditions, and multiple recycling was achieved.
Multiple recycling and utilization of cross-linked polyacrylonitrile polymer materials has been achieved, improving the mechanical properties of the materials, and reducing environmental pollution and resource waste.
Smart Images
Figure CN114989463B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of light-responsive molecular materials and the field of recyclable plastics, and particularly relates to a preparation method of light-controlled reversible coordination cross-linked polyacrylonitrile and a recycling method thereof. Background Art
[0002] Polymers are important high-performance structural and sustainable materials. Their recycling is crucial for sustainable social development. Currently, linear polymers can be recycled through solution reprocessing and melt processing. However, many applications require insoluble and non-meltable cross-linked polymers with superior mechanical properties. However, their insoluble and non-meltable nature precludes recycling of traditional cross-linked polymers, resulting in environmental pollution and resource waste.
[0003] Recently, people have prepared a series of reversibly cross-linked polymers (adaptive networks and glass-like polymers) based on the strategy of reversible cross-linking. Due to the presence of reversible cross-linking points, they can be recycled. However, industrially mass-produced polymers do not have the reversible reactive groups of the reported adaptive networks or glass-like polymers, making them difficult to be directly used to prepare reversibly cross-linked polymers. How to use industrially mass-produced polymers to prepare reversibly cross-linked polymers is a recognized bottleneck problem. Therefore, using industrially mass-produced polymers to prepare recyclable reversibly cross-linked polymer materials has both theoretical value and prospects for application transformation. Summary of the Invention
[0004] The present invention addresses the aforementioned problems of the prior art by providing a method for preparing and recycling light-controlled reversibly coordinated cross-linked polyacrylonitrile. The present invention utilizes a light-controlled reversibly coordinated ruthenium cross-linking agent to prepare a reversibly cross-linked polyacrylonitrile polymer material with excellent recyclability. The material can be recycled multiple times in the presence of only a solvent and light. The method provided by the present invention solves the problem of using industrially mass-produced polymers to prepare reversibly cross-linked polymers.
[0005] The method for preparing the light-controlled reversible coordination cross-linked polyacrylonitrile of the present invention comprises the following steps:
[0006] The light-controlled reversible coordination ruthenium cross-linking agent and polyacrylonitrile are fully dissolved in N,N-dimethylformamide to obtain a mixed solution; the obtained mixed solution is heated at 80° C. to form a cross-linked polyacrylonitrile polymer material.
[0007] The added mass of the light-controlled reversible coordination ruthenium crosslinker is 5-15% of the mass of the polyacrylonitrile (the added mass of the light-controlled reversible coordination ruthenium crosslinker is not strictly limited. The mass fraction used in the embodiment is 5-15%, and the range can be appropriately expanded or narrowed on this basis). This method adjusts the crosslink density of the material by adjusting the mass fraction of the light-controlled reversible coordination ruthenium crosslinker, and thus adjusts the mechanical properties of the crosslinked polyacrylonitrile polymer material.
[0008] The polyacrylonitrile is a conventional industrially produced polyacrylonitrile, and its structural formula is shown in the following formula I:
[0009]
[0010]
[0011] The structural formula of the light-controlled reversible coordination ruthenium cross-linker (RuA) is shown in Formula II below:
[0012]
[0013] The light-controlled reversible coordination ruthenium cross-linker (RuA) is prepared by a method comprising the following steps:
[0014] a) performing a coordination reaction between the compound 2,2'-bipyridine represented by formula II-a and ruthenium trichloride trihydrate to obtain a compound represented by formula II-b;
[0015] b) reacting the compound represented by formula II-b with silver hexafluorophosphate to obtain a light-controlled reversible coordinated ruthenium cross-linking agent represented by formula II.
[0016]
[0017] In step a), the molar ratio of the compound 2,2'-bipyridine represented by formula II-a to ruthenium trichloride trihydrate is 2:1 to 2.1:1.
[0018] In step b), the molar ratio of the compound represented by formula II-b to silver hexafluorophosphate is 1:2 to 1:2.5.
[0019] In step a), N,N-dimethylformamide is added to a mixture of 2,2'-bipyridine, ruthenium trichloride trihydrate and lithium chloride (the amount of lithium chloride added does not need to be strictly limited, for example, the ratio of ruthenium trichloride trihydrate to lithium chloride is 1:6.6), and the mixture is refluxed at 160°C under a nitrogen atmosphere for 6 hours; after the reaction solution is cooled to room temperature, acetone is added dropwise to the reaction mixture, and the resulting mixed solution is filtered, washed with water, and dried to obtain a compound represented by formula II-b.
[0020] In step b), ethanol and deionized water are added to a mixture of the compound represented by Formula II-b and silver hexafluorophosphate (the ratio of ethanol to deionized water is not strictly limited. In the embodiment, a volume ratio of 1:1 is used, and the range can be appropriately expanded or narrowed on this basis). The reaction is refluxed at 80°C under a nitrogen atmosphere for 12 hours; the mixed solution is filtered, the solvent in the filtrate is concentrated by vacuum distillation, and a saturated ammonium hexafluorophosphate solution is added to the mixed solution until no new precipitate is generated. The resulting mixed solution is filtered, washed with water, and dried to finally obtain a light-controlled reversible coordination ruthenium crosslinker represented by Formula II.
[0021] The recycling method of the reversible coordinated cross-linked polyacrylonitrile of the present invention is as follows:
[0022] The cross-linked polyacrylonitrile polymer material is exposed to an LED light source in the presence of N,N-dimethylformamide to obtain a de-crosslinked mixed solution. The de-crosslinked mixed solution is then heated and re-molded at 80°C to obtain a recycled cross-linked polyacrylonitrile polymer material. Repeating these steps can achieve multiple recycling cycles of the cross-linked polyacrylonitrile polymer material.
[0023] The LED light source is light with a wavelength of 470 nm or includes light with a wavelength of 470 nm.
[0024] In the specific implementation process, the feed ratio used is 100 mg of cross-linked polyacrylonitrile polymer material and 10-30 mL of N,N-dimethylformamide. The ratio can be increased or decreased based on this, and is not strictly limited.
[0025] Compared to the prior art, the present invention provides a method for preparing and recycling light-controlled reversibly coordinated cross-linked polyacrylonitrile. The polymer matrix used in the present invention is derived from industrially mass-produced polyacrylonitrile, which is then directly used to prepare the reversibly cross-linked polymer. The cross-linker employed is a light-controlled reversibly coordinated ruthenium cross-linker, marking the first application of a light-controlled reversible cross-linker in the recycling of cross-linked polymers. The present invention enables multiple recycling of cross-linked polyacrylonitrile polymer materials by controlling illumination and heating conditions. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 The H NMR spectrum of the photo-controlled reversible coordination ruthenium cross-linker is shown.
[0027] Figure 2 Shown is the hydrogen-hydrogen correlation spectrum of the photocontrolled reversible coordinated ruthenium crosslinker.
[0028] Figure 3 The carbon NMR spectrum of the photo-controlled reversible coordination ruthenium cross-linker is shown.
[0029] Figure 4The stress-strain curves of cross-linked polyacrylonitrile polymer and control material are shown. Figure 4 It can be seen that with the increase of the mass fraction of the light-controlled reversible coordination ruthenium cross-linker, the mechanical properties of the cross-linked polyacrylonitrile polymer material gradually enhance.
[0030] Figure 5 The Young's modulus and elongation at break of cross-linked polyacrylonitrile polymer and control material are shown. Figure 5 It can be seen that with the increase of the mass fraction of the light-controlled reversible coordination ruthenium cross-linker, the Young's modulus and elongation at break of the cross-linked polyacrylonitrile polymer material gradually increase.
[0031] Figure 6 The Young's modulus and elongation at break of cross-linked polyacrylonitrile polymer material PAN-10%RuA and three recycling times are shown. Figure 6 It can be seen that after three recycling cycles, the cross-linked polyacrylonitrile polymer material PAN-10%RuA still maintains good Young's modulus and elongation at break. DETAILED DESCRIPTION
[0032] To further illustrate the present invention, the following detailed description of the preparation and recycling methods of the light-controlled reversibly coordinated cross-linked polyacrylonitrile provided by the present invention is provided in conjunction with examples. However, it should be understood that these descriptions are intended only to further illustrate the features and advantages of the present invention and are not intended to limit the scope of the present invention.
[0033] 2,2'-Bipyridine, ruthenium trichloride trihydrate, lithium chloride, N,N-dimethylformamide, silver hexafluorophosphate, and ammonium hexafluorophosphate used in the following examples were purchased from Anaiji Chemical, and ethanol and acetone were purchased from Sinopharm Chemical Reagent Co., Ltd.
[0034] The polyacrylonitrile used was an industrial variety (company: Du Pont, model R60) with a weight average molecular weight of approximately 185,000 gmol. -1 , but is not limited to this type of polyacrylonitrile.
[0035] Example 1: Synthesis of a Photo-Controlled Reversible Coordination Crosslinker
[0036]
[0037] a) In a 10 mL round-bottom flask, 2,2'-bipyridine (264.2 mg, 1.7 mmol), ruthenium trichloride trihydrate (220.0 mg, 0.8 mmol), and lithium chloride (260.2 mg, 6.1 mmol) were added, followed by the addition of 2 mL of N,N-dimethylformamide. The resulting mixture was refluxed at 160°C under a nitrogen atmosphere for 6 h. After cooling to room temperature, 10 mL of acetone was added to the flask. The resulting mixture was filtered, washed with water, and dried to obtain a black solid powder.
[0038] b) The black solid powder of step a) and silver hexafluorophosphate (151.0 mg, 0.6 mmol) were added to a 100 mL round-bottom flask, followed by the addition of 10 mL of ethanol and 10 mL of deionized water; the resulting mixture was refluxed at 80° C. under a nitrogen atmosphere for 12 h; the mixed solution was filtered, the solvent in the filtrate was concentrated to about 5 mL by vacuum distillation, and a saturated ammonium hexafluorophosphate solution was added to the mixed solution until no new precipitate was generated. The resulting mixed solution was filtered, washed with water, and dried to obtain the final light-controlled reversible coordination ruthenium crosslinker. Figure 1-3 The hydrogen nuclear magnetic resonance spectrum, hydrogen-hydrogen correlation spectrum and carbon nuclear magnetic resonance spectrum of the photocontrolled reversible coordination ruthenium cross-linker are shown respectively.
[0039] Example 2: Preparation of recyclable and mechanically strong polyacrylonitrile polymer material using industrial polymer and light-controlled reversible coordination crosslinker
[0040] a) fully dissolving 1.0 g of polyacrylonitrile and 100.0 mg of a light-controlled reversible coordination ruthenium crosslinker in N,N-dimethylformamide to obtain a mixed solution;
[0041] b) pouring the mixture from step a) into a mold, heating the mixture at 80°C for 12 hours, and then removing the solvent from the system. After demolding, hot pressing the mixture at 120°C for 1 hour, and then annealing the mixture in a vacuum drying oven at 120°C for 2 days, thereby obtaining a cross-linked polyacrylonitrile polymer material, PAN-10% RuA;
[0042] c) in steps a) and b), no light-controlled reversible coordination ruthenium crosslinking agent is added, thereby preparing an uncrosslinked control group polyacrylonitrile polymer material PAN;
[0043] d) In steps a) and b), 50.0 mg and 150.0 mg of a light-controlled reversible coordination ruthenium crosslinker are added, respectively, to prepare crosslinked polyacrylonitrile polymer materials PAN-5%RuA and PAN-15%RuA, respectively. Figure 4 The stress-strain curves of cross-linked polyacrylonitrile polymer material and control material are shown. Figure 5 The Young's modulus and elongation at break of the cross-linked polyacrylonitrile polymer material and the control material are shown.
[0044] Example 3: Recycling Method of Cross-linked Polyacrylonitrile Polymer Material (Take PAN-10% RuA as an Example)
[0045] a) About 100 mg of PAN-10% RuA was minced and placed in a 50 mL round-bottom flask, followed by the addition of 10 mL of N,N-dimethylformamide;
[0046] b) irradiating the mixed solution in step a) with stirring under a Philips full-spectrum LED white light lamp (model: PAR 38, including light with a wavelength of 470 nm) until a uniform solution is formed;
[0047] c) pouring the mixture from step b) into a mold, heating the mixture at 80°C for 12 hours, and then removing the solvent from the system. After demolding, hot pressing the mixture at 120°C for 1 hour, and then annealing the mixture in a vacuum drying oven at 120°C for 2 days, thereby obtaining a recovered cross-linked polyacrylonitrile polymer material, PAN-10% RuA.
[0048] d) Repeating steps a), b), and c) can achieve multiple recycling of the cross-linked polyacrylonitrile polymer material. Figure 6 The Young's modulus and elongation at break of the cross-linked polyacrylonitrile polymer material PAN-10%RuA and three recycling times are shown.
[0049] The above embodiments are merely intended to facilitate understanding of the methods and core concepts of the present invention. It should be noted that those skilled in the art will readily appreciate that various improvements and modifications may be made to the present invention without departing from the principles of the present invention, and such improvements and modifications fall within the scope of the claims. Therefore, the present invention is not limited to the embodiments shown herein, but is intended to be construed within the broadest scope consistent with the principles and novel features disclosed herein.
Claims
1. A method for preparing light-controlled reversible coordination cross-linked polyacrylonitrile, characterized in that: The light-controlled reversible coordination ruthenium crosslinker and polyacrylonitrile are fully dissolved in N,N-dimethylformamide to obtain a mixed solution; the obtained mixed solution is heated at 80° C. to form a cross-linked polyacrylonitrile polymer material; The structural formula of the polyacrylonitrile is shown in the following formula I: ； The structural formula of the light-controlled reversible coordination ruthenium cross-linker is shown in Formula II below: ； The added mass of the light-controlled reversible coordination ruthenium cross-linking agent is 5-15% of the mass of polyacrylonitrile.
2. The method for recycling the reversibly coordinated cross-linked polyacrylonitrile prepared according to claim 1, characterized in that: In the presence of N,N-dimethylformamide, the cross-linked polyacrylonitrile polymer material is placed under an LED light source for irradiation to obtain a de-crosslinked mixed solution; the de-crosslinked mixed solution is re-heated at 80° C. and shaped to obtain a recycled cross-linked polyacrylonitrile polymer material; and the above steps are repeated to achieve multiple recycling of the cross-linked polyacrylonitrile polymer material. The LED light source is light with a wavelength of 470 nm or includes light with a wavelength of 470 nm.