A polyrotaxane material based on deep eutectic system and preparation method and application thereof

Abstract

The application belongs to the technical field of supramolecular material processing, and particularly relates to a kind of polyrotaxane materials based on deep eutectic system and its preparation method and application.Through organic acids such as thioctic acid and citric acid as hydrogen bond donor, polyrotaxane as hydrogen bond acceptor, both use reversible hydrogen bond supramolecular interaction to construct dynamic solvation network, so as to realize the efficient dissolution and stable dispersion of cyclodextrin-based polyrotaxane under mild conditions.On this basis, by regulating the type and amount of organic acid, the molar ratio of donor and acceptor and the water content of the system, or combined with physical / chemical crosslinking means, the dissolved polyrotaxane can be controllably converted into elastomer, and the polyrotaxane elastomer material with adjustable mechanical properties and toughness can be obtained.The method has good adaptability and universality for polyrotaxanes with different chain lengths and polyrotaxanes with different charge characteristics (cationic and anionic), and the deep eutectic system can be recycled and used, and still can maintain the dissolution and processing ability after several cycles.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of supramolecular material processing, and particularly relates to a kind of polyrotaxane materials based on deep eutectic system and its preparation method and application. BACKGROUND

[0002] The polyrotaxane (CD-PRs) based on cyclodextrin has a dense intramolecular and intermolecular hydrogen bond network between cyclodextrin units, which makes its solubility in common solvents extremely poor, which brings great obstacles to its direct processing and application. Specifically, CD-PRs can only be dissolved in dimethyl sulfoxide, ice alkali water, N,N-dimethylformamide with lithium salt, and ionic liquid, and chemical modification in the above solvents faces great challenges in cost and pollution. So far, the functional integration of CD-PRs depends on prior chemical modification to improve its solubility and enhance processability. SUMMARY

[0003] Based on the above problems, the application provides a kind of polyrotaxane material based on deep eutectic system and its preparation method and application, which realizes the green solvent-free processing of polyrotaxane by using intermolecular hydrogen bond interaction. Specifically, the polyrotaxane is dissolved in the solution system by the deep eutectic solution system, and then the polyrotaxane is melt processed to convert it into a functional material with elasticity and adhesion. This method not only broadens the application field of cyclodextrin-based polyrotaxane, but also establishes a multifunctional, solvent-free mechanical interlocking polymer processing route, which can be used to prepare high-performance supramolecular materials.

[0004] Therefore, the technical scheme of the application discloses a preparation method of a polyrotaxane material based on a deep eutectic system, which comprises

[0005] The organic acid and the cyclodextrin polyrotaxane are heated and dissolved to form a deep eutectic system, and a polyrotaxane material is obtained.

[0006] Among them, the organic acid is lipoic acid or citric acid-choline chloride.

[0007] Further, when the organic acid is lipoic acid, 7.5 mmol of lipoic acid is added per 0.2 g of cyclodextrin polyrotaxane; when the organic acid is citric acid-choline chloride, 83 mmol of citric acid and 14 mmol of choline chloride are added per 0.2 g of cyclodextrin polyrotaxane.

[0008] Further, the heating and dissolving temperature is 90-150℃, and the time is 0.5-3h.

[0009] Further, a crosslinking agent can be added to the deep eutectic system to form a polyrotaxane material after melting.

[0010] Further, the melting temperature is 90-150℃, and the time is 20 min.

[0011] Further, the crosslinking agent is N,N'-methylene bisacrylamide.

[0012] Also, the polyrotaxane material obtained according to the above preparation method and its application as an elastomer material in preparing a thin film, a coating or a bonding and coating.

[0013] Compared with the prior art, the present application has the following beneficial effects:

[0014] 1. The preparation process is simple, easy to operate and pollution-free.

[0015] 2. The prepared polyrotaxane material has good elasticity.

[0016] 3. The prepared polyrotaxane material has good adhesion.

[0017] 4. The processing method can realize recycling of the polyrotaxane material. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 are scanning electron micrographs, wherein (a) is a scanning electron micrograph of lipoic acid at 1000 times magnification, (b) is a scanning electron micrograph of cyclodextrin polyrotaxane at 1000 times magnification, and (c) is a scanning electron micrograph of the polyrotaxane material obtained in Example 1 at 5000 times magnification.

[0019] Figure 2 are spectral analysis graphs of the polyrotaxane material prepared in Example 1, and lipoic acid and cyclodextrin polyrotaxane, wherein (a) is a Raman spectrum, (b) is a Fourier transform infrared spectrum, (c) is an X-ray diffraction spectrum, and (d) is an optical picture of the polyrotaxane material of Example 1.

[0020] Figure 3 are polyrotaxane material recycling process and result graphs of Example 3, wherein (a) is an optical photograph of the recycling process, (b) is a nuclear magnetic resonance spectrum of the recycled polyrotaxane, (c) is an X-ray diffraction spectrum of the recycled polyrotaxane, and (d) is a Fourier transform infrared spectrum of the recycled polyrotaxane.

[0021] Figure 4 is a nuclear magnetic resonance spectrum of the recycled polyrotaxane in Example 2.

[0022] Figure 5 is a tensile property of the polyrotaxane material in Example 3.

[0023] Figure 6 are adhesion property test results of the polyrotaxane material in Example 4, wherein the adhesion material of (a) is wood, the adhesion material of (b) is PMMA, and the adhesion material of (c) is iron. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0025] The relative arrangement, numerical expressions and numerical values of the components and steps set forth in the embodiments are not limiting to the scope of the present application, unless otherwise specifically stated. Meanwhile, it should be understood that the sizes of the various parts shown in the drawings are not drawn in accordance with the actual proportional relationship for the convenience of description. The techniques, methods and devices known to those of ordinary skill in the related art can not be discussed in detail, but should be considered as part of the authorized description, if appropriate. In all examples shown and discussed herein, any specific value should be interpreted as merely exemplary, and not as a limitation. Therefore, other examples of the exemplary embodiments can have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0026] Unless otherwise specified, the meanings of the scientific and technical terms in the specification are the same as those generally understood by those skilled in the art, but if there is a conflict, the definitions in the specification shall prevail.

[0027] To this end, the technical solutions of the present application disclose a preparation method of a polyrotaxane material based on a deep eutectic system, comprising: heating and dissolving an organic acid and a cyclodextrin polyrotaxane to form a deep eutectic system, to obtain a polyrotaxane material; wherein the organic acid is lipoic acid or citric acid-choline chloride.

[0028] In this process, lipoic acid, citric acid and other organic acids act as hydrogen bond donors, and polyrotaxane acts as a hydrogen bond acceptor. They use reversible hydrogen bond supramolecular interaction to construct a dynamic solvation network, thereby realizing efficient dissolution and stable dispersion of cyclodextrin-based polyrotaxane under mild conditions.

[0029] On this basis, by adjusting the type and amount of organic acid, the molar ratio of donor and acceptor, and the water content of the system, or combining physical / chemical cross-linking means, the dissolved polyrotaxane can be controllably converted into an elastomer, and a polyrotaxane elastomer with adjustable mechanical properties and toughness can be obtained. This method has good adaptability and universality for polyrotaxanes of different chain lengths and polyrotaxanes with different charge characteristics (cationic and anionic), and the deep eutectic system can be recycled and reused, and still maintains the ability to dissolve and process after multiple cycles.

[0030] In some preferred embodiments, when the organic acid is lipoic acid, the amount of lipoic acid added per 0.2 g of cyclodextrin polyrotaxane is ≥ 7.5 mmol; when the organic acid is citric acid-choline chloride, the amount of citric acid added per 0.2 g of cyclodextrin polyrotaxane is ≥ 83 mmol, and the amount of choline chloride added is ≥ 14 mmol.

[0031] In further embodiments, the purpose of heating and dissolving is to dissolve the polyrotaxane and react with lipoic acid or citric acid to build a dynamic solvation network. When lipoic acid is used as the organic acid, the heating temperature is preferably 150 °C, and when citric acid is used as the organic acid, the heating temperature is preferably 90 °C. The heating time is preferably 0.5-3 h.

[0032] It should be noted that the purpose of adding the organic acid in the present application is to dissolve the cyclodextrin polyrotaxane, and the product formed directly after dissolution or the product formed through subsequent processing are all "polyrotaxane materials" according to the present application. For example, the deep eutectic system formed by the organic acid and the cyclodextrin polyrotaxane itself is a polyrotaxane material. A crosslinking agent or other ingredients can also be added according to the desired product properties or the application field, and the cyclodextrin polyrotaxane-based processed product formed thereby is also a polyrotaxane material according to the present application.

[0033] In some preferred embodiments, a crosslinking agent can be added to the deep eutectic system and melted to form a polyrotaxane material. The melting temperature is preferably 90-150 °C, and the time is 20 min. The crosslinking agent is preferably N,N'-methylenebisacrylamide.

[0034] The technical effects of the polyrotaxane materials prepared by the preparation method of the present application will be described in detail below through specific examples.

[0035] Example 1 Preparation of a polyrotaxane material

[0036] Preparation of a lipoic acid-polyrotaxane deep eutectic system using lipoic acid as the organic acid: 1.5 g of lipoic acid and 0.2 g of polyrotaxane were mixed and heated to 150 °C, and stirring was performed for 30 min to obtain a lipoic acid-polyrotaxane deep eutectic system. The solution is a polyrotaxane material.

[0037] Example 2 Preparation of a polyrotaxane material

[0038] Preparation of a citric acid-choline chloride-polyrotaxane deep eutectic system using citric acid as the organic acid: 2.11 g of citric acid, 4.588 g of choline chloride, and 0.2 g of polyrotaxane were heated to 90 °C, and stirring was performed for 3 h to obtain a citric acid-choline chloride-polyrotaxane deep eutectic system. The system is a polyrotaxane material.

[0039] Example 3 Preparation of a polyrotaxane material

[0040] To the lipoic acid-polyrotaxane deep eutectic system prepared in Example 1, 0.2 g (5% by mass) of N,N'-methylenebisacrylamide was added at 150°C, and reacted for 20 min, and cooled to room temperature to obtain a polyrotaxane material.

[0041] Example 4

[0042] To the lipoic acid-polyrotaxane deep eutectic system prepared in Example 2, 0.2 g (5% by mass) of N,N'-methylenebisacrylamide was added at 150°C, and reacted for 20 min, and cooled to room temperature to obtain a polyrotaxane material.

[0043] Test Example 1: texture analysis

[0044] The polyrotaxane material obtained in Example 1 was subjected to electron microscopy scanning and spectral analysis, and electron microscopy scanning images and spectral analysis images as shown in Figure 1 , Figure 2 were obtained; wherein, Figure 1 (a) is lipoic acid at 1000 times magnification, Figure 1 (b) is cyclodextrin polyrotaxane at 1000 times magnification, Figure 1 (c) is polyrotaxane material at 5000 times magnification; Figure 2 (a) is Raman spectrum, Figure 2 (b) is Fourier transform infrared spectrum, and Figure 2 (c) is X-ray diffraction spectrum; it can be seen from the figures that, before deep eutectic processing, both lipoic acid and cyclodextrin polyrotaxane are powdery materials, and after deep eutectic processing, due to hydrogen bonding interaction and good dispersion of polyrotaxane in lipoic acid, the prepared polyrotaxane material has a smooth surface, proving that the processing is successful. The Raman spectrum proves that lipoic acid and cyclodextrin polyrotaxane are successfully converted into polyrotaxane material by using deep eutectic system processing. The Fourier transform infrared spectrum proves that lipoic acid and cyclodextrin polyrotaxane interact through hydrogen bonding, and then realize processing. The X-ray diffraction spectrum proves that lipoic acid and polyrotaxane interact, so that polyrotaxane is successfully dispersed in the polyrotaxane material, further indicating that the processing is successful.

[0045] Test Example 2: recovery experiment

[0046] Experimental method

[0047] 0.8 ml of the polyrotaxane material described in Example 2 was taken respectively and added to 10 ml of ultrapure water, shaken for 2 min, centrifuged at 8000 rpm for 2 min, the supernatant was poured out, and then washed with 20 ml of ultrapure water for three times, and then freeze-dried at -80°C for 24 hours to obtain recovered polyrotaxane.

[0048] Take 0.3 g of the polyrotaxane material described in Example 3 into 6 ml of N,N-dimethylformamide solution, heat to 150 degrees Celsius, stir for 1 h to 3 h, then wait for the solution to cool, add 20 ml of ultrapure water, shake vigorously for 2 minutes, then centrifuge the above mixed solution at 8000 rpm for 2 minutes, pour out the supernatant, and then wash with 20 ml of ultrapure water for three times, then freeze-dry at -80 degrees Celsius for 24 hours to obtain the recovered polyrotaxane.

[0049] Figure 3 For the recovered polyrotaxane in Example 3, wherein, Figure 3 (a) is an optical photo of the recovered polyrotaxane, Figure 3 (b) is the nuclear magnetic resonance spectrum of the recovered polyrotaxane, Figure 3 (c) is the X-ray diffraction spectrum of the recovered polyrotaxane, Figure 3 (d) is the Fourier transform infrared spectrum of the recovered polyrotaxane. The above results prove that the chemical properties of the polyrotaxane remain unchanged after melt processing using the deep eutectic system, proving the feasibility of melt processing of polyrotaxane using deep eutectic. Figure 4 For the nuclear magnetic resonance spectrum of the recovered polyrotaxane in Example 2. Prove the stability of the polyrotaxane in the deep eutectic system.

[0050] Test Example 3 Performance Test

[0051] The polyrotaxane materials obtained in Example 3 and Example 4 at different mass fractions were tested for tensile properties and adhesion properties. Specifically:

[0052] Tensile properties: Uniaxial tensile test was carried out at room temperature using ETM101B universal testing machine (WANCE, China). The tensile rate was set to 10 mm / min, unless otherwise specified. The hydrogel sample was prepared into a dumbbell shape (type 2, GB / T 528-1998), and the distance between the clamps was 10 mm.

[0053] Adhesion properties: The adhesion test used a lap shear method, which was carried out on an ETM101B universal testing machine (Wance, China) at a speed of 30 mm / min. All samples were clamped between two pieces of wood, PMAA and iron. Tensile wood, PMAA and iron, when cohesive or adhesive failure occurs, record the maximum tensile force. Divide the tensile force at break by the area of the PTA material to obtain the value of the adhesion strength.

[0054] Experimental results and result analysis: As Figure 5 , Figure 6As shown, the addition of polyrotaxane in elastomer and adhesive material can effectively improve its performance. Specifically, for elastomer material, the addition of polyrotaxane can comprehensively control the tensile deformation, tensile modulus, toughness and elastic modulus of the material, breaking through the defects of traditional filler materials. For adhesives, the addition of polyrotaxane can effectively improve the adhesion and increase its application scenarios.

[0055] At this point, those skilled in the art recognize that, although embodiments of the present application have been fully set forth and described herein, many other variations or modifications can be determined or deduced directly from the disclosure of the present application in accordance with the principles of the present application without departing from the spirit and scope of the present application. Therefore, the scope of the present application should be understood and recognized as covering all such other variations or modifications.

Claims

1. A method for preparing polyrotaxane materials based on a deep eutectic system, characterized in that, include: Thioctic acid or citric acid-choline chloride and cyclodextrin polyrotaxane are heated and dissolved to form a deep eutectic system, thus obtaining polyrotaxane material.

2. The preparation method according to claim 1, characterized in that, When lipoic acid is used, ≥7.5 mmol of lipoic acid is added to every 0.2 g of cyclodextrin polyrotaxane; when citric acid-choline chloride is used, ≥83 mmol of citric acid and ≥14 mmol of choline chloride are added to every 0.2 g of cyclodextrin polyrotaxane.

3. The preparation method according to claim 1, characterized in that, The heating and melting temperature is 90-150℃, and the time is 0.5-3h.

4. The preparation method according to claim 1, characterized in that, In the deep eutectic system, a crosslinking agent can also be added to form polyrotaxane material after melting.

5. The preparation method according to claim 4, characterized in that, The melting temperature is 90-150℃, and the melting time is 20 minutes.

6. The preparation method according to claim 4, characterized in that, The crosslinking agent is N,N'-methylenebisacrylamide.

7. A polyrotaxane material obtained by any one of the preparation methods according to claims 1-6.

8. The application of the polyrotaxane material according to claim 7 as an elastomer material in the preparation of films and coatings.

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