Polyrotaxane material based on deep eutectic system as well as preparation method and application of polyrotaxane material

Abstract

The invention belongs to the technical field of supramolecular material processing, and particularly relates to a polyrotaxane material based on a deep eutectic system as well as a preparation method and application of the polyrotaxane material. Organic acids such as lipoic acid and citric acid are used as hydrogen bond donors, polyrotaxane is used as a hydrogen bond receptor, and the lipoic acid and the polyrotaxane construct a dynamic solvation network under the reversible hydrogen bond supramolecular action, so that efficient dissolution and stable dispersion of cyclodextrin-based polyrotaxane are realized under mild conditions. On the basis, the dissolved-state polyrotaxane can be controllably converted into an elastomer by regulating and controlling the type and dosage of the organic acid, the molar ratio of a donor to an acceptor and the water content of a system or combining a physical / chemical cross-linking means, so that the polyrotaxane elastic material with adjustable mechanical property and toughness is obtained. The method has good adaptability and universality to polyrotaxane with different chain segment lengths and polyrotaxane (cationic type and anionic type) with different charge characteristics, and the deep eutectic system can be recycled and can still maintain dissolving and processing capabilities after multiple cycles.

Description

Technical Field

[0001] The present invention belongs to the technical field of supramolecular material processing, and in particular relates to a polyrotaxane material based on a deep eutectic system, and a preparation method and application thereof. Background Art

[0002] Cyclodextrin-based polyrotaxanes (CD-PRs) suffer from extremely poor solubility in common solvents due to the dense intramolecular and intermolecular hydrogen-bonding networks between cyclodextrin units, posing a significant obstacle to their direct processing and application. Specifically, CD-PRs are only soluble in dimethyl sulfoxide, icy alkaline water, lithium-doped N,N-dimethylformamide, and ionic liquids. Chemical modification in these solvents faces significant challenges due to cost and pollution. To date, functional integration of CD-PRs has relied on prior chemical modification to improve their solubility and processability. Summary of the Invention

[0003] To address the above issues, the present application provides a deep eutectic polyrotaxane material, its preparation method, and application. This method utilizes intermolecular hydrogen bonding to achieve green, solvent-free processing of polyrotaxanes. Specifically, the polyrotaxane is dissolved in a solution system using a deep eutectic solution system, and then melt-processed to convert it into a functional material with elasticity and adhesion. This method not only broadens the application field of cyclodextrin-based polyrotaxanes but also establishes a multifunctional, solvent-free processing route for mechanically interlocked polymers, which can be used to prepare high-performance supramolecular materials.

[0004] To this end, the technical solution of the present application discloses a method for preparing 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 thioctic acid or citric acid-choline chloride.

[0005] Furthermore, when the organic acid is thioctic acid, the amount of thioctic acid added to each 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 to each 0.2 g of cyclodextrin polyrotaxane is ≥83 mmol, and the amount of choline chloride added to each 0.2 g of cyclodextrin polyrotaxane is ≥14 mmol.

[0006] Furthermore, the heating and dissolving temperature is 90-150° C., and the time is 0.5-3 h.

[0007] Furthermore, a cross-linking agent may be added to the deep eutectic system and melted to form a polyrotaxane material.

[0008] Furthermore, the melting temperature is 90-150° C., and the melting time is 20 minutes.

[0009] Furthermore, the cross-linking agent is N,N'-methylenebisacrylamide.

[0010] Also, the polyrotaxane material obtained according to the above preparation method and its use as an elastomeric material in preparing films, coatings, or bonding and coating.

[0011] Compared with the prior art, the present invention has the following beneficial effects: 1. The preparation process is simple, easy and pollution-free.

[0012] 2. The prepared polyrotaxane material has good elasticity.

[0013] 3. The prepared polyrotaxane material has good adhesion.

[0014] 4. The processing method can achieve recycling of polyrotaxane materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 are scanning electron microscope images, wherein (a) is a scanning electron microscope image of lipoic acid at a magnification of 1000 times, (b) is a scanning electron microscope image of cyclodextrin polyrotaxane at a magnification of 1000 times, and (c) is a scanning electron microscope image of the polyrotaxane material obtained in Example 1 at a magnification of 5000 times.

[0016] Figure 2 The polyrotaxane material prepared in Example 1, as well as the spectral analysis diagrams of lipoic acid and cyclodextrin polyrotaxane, wherein (a) is the Raman spectrum, (b) is the Fourier transform infrared spectrum, (c) is the X-ray diffraction spectrum, and (d) is the optical image of the polyrotaxane material in Example 1.

[0017] Figure 3 Figure 3 shows the polyrotaxane material recovery process and results of Example 3, where (a) is an optical photograph of the recovery process, (b) is the nuclear magnetic resonance spectrum of the recovered polyrotaxane, (c) is the X-ray diffraction spectrum of the recovered polyrotaxane, and (d) is the Fourier transform infrared spectrum of the recovered polyrotaxane.

[0018] Figure 4 This is the nuclear magnetic resonance spectrum of the polyrotaxane recovered in Example 2.

[0019] Figure 5 This is the tensile property of the polyrotaxane material in Example 3.

[0020] Figure 6 These are the test results of the adhesion performance of the polyrotaxane materials in Example 4, where the adhesion material of (a) is wood, the adhesion material of (b) is PMMA, and the adhesion material of (c) is iron. DETAILED DESCRIPTION

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0022] Unless otherwise specifically stated, the relative arrangement of the parts and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to actual proportional relationships. The techniques, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific values ​​should be interpreted as being merely exemplary and not as limitations. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0023] Unless otherwise specified, the meanings of technical terms in this specification are the same as those generally understood by those skilled in the art. However, if there is any conflict, the definitions in this specification shall prevail.

[0024] To this end, the technical solution of the present application discloses a method for preparing 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 thioctic acid or citric acid-choline chloride.

[0025] In this process, organic acids such as lipoic acid and citric acid act as hydrogen bond donors, and polyrotaxanes act as hydrogen bond acceptors. The two utilize reversible hydrogen bond supramolecular interactions to construct a dynamic solvation network, thereby achieving efficient dissolution and stable dispersion of cyclodextrin-based polyrotaxanes under mild conditions.

[0026] On this basis, by manipulating the type and dosage of organic acids, the donor-acceptor molar ratio, and the water content of the system, or by combining physical or chemical crosslinking methods, dissolved polyrotaxanes can be controllably converted into elastomers, resulting in polyrotaxane elastomers with adjustable mechanical properties and toughness. This method exhibits excellent adaptability and versatility for polyrotaxanes of varying chain lengths and charge characteristics (both cationic and anionic). Furthermore, the deep eutectic system is recyclable and maintains solubility and processability after multiple cycles.

[0027] In some preferred embodiments, when the organic acid is thioctic acid, the amount of thioctic acid added to each 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 to each 0.2 g of cyclodextrin polyrotaxane is ≥83 mmol, and the amount of choline chloride added to each 0.2 g of cyclodextrin polyrotaxane is ≥14 mmol.

[0028] In a further embodiment, the purpose of heating and dissolving is to dissolve the polyrotaxane and react with lipoic acid or citric acid to construct 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., and the heating time is preferably 0.5-3 h.

[0029] It should be noted that the purpose of adding an organic acid in this application is to dissolve the cyclodextrin polyrotaxane, and the products directly formed after the dissolution or the products formed through subsequent processing are all "polyrotaxane materials" described in this application. For example, the deep eutectic system formed by the organic acid and the cyclodextrin polyrotaxane itself is a polyrotaxane material; it is also possible to selectively add a cross-linking agent or blend with other ingredients according to the desired product properties or the field of application, and the cyclodextrin polyrotaxane processed product formed is also a polyrotaxane material described in this application.

[0030] In some preferred embodiments, a cross-linking agent may be added to the deep eutectic system and melted to form a polyrotaxane material. The melting temperature is preferably 90-150° C., and the melting time is 20 min. The cross-linking agent is preferably N,N′-methylenebisacrylamide.

[0031] The technical effects of the polyrotaxane material obtained by the preparation method of the present application will be described in detail below through specific examples.

[0032] Example 1 Preparation of polyrotaxane materials A lipoic acid-polyrotaxane deep eutectic system was prepared using lipoic acid as an organic acid: 1.5 g of lipoic acid and 0.2 g of polyrotaxane were mixed and heated to 150° C., and stirred for 30 minutes to obtain a lipoic acid-polyrotaxane deep eutectic system. The solution was the polyrotaxane material.

[0033] Example 2 Preparation of polyrotaxane materials Preparation of a citric acid-choline chloride-polyrotaxane deep eutectic system using citric acid as an organic acid: 2.11 g of citric acid, 4.588 g of choline chloride, and 0.2 g of polyrotaxane were heated to 90 degrees Celsius and stirred for 3 hours to obtain a citric acid-choline chloride-polyrotaxane deep eutectic system, which is a polyrotaxane material.

[0034] Example 3 Preparation of polyrotaxane materials 0.2 g (5% by mass) of N,N'-methylenebisacrylamide was added to the lipoic acid-polyrotaxane deep eutectic system prepared in Example 1 at 150°C, reacted for 20 minutes, and cooled to room temperature to obtain a polyrotaxane material.

[0035] Example 4

[0036] 0.2 g (5% by mass) of N,N'-methylenebisacrylamide was added to the lipoic acid-polyrotaxane deep eutectic system prepared in Example 2 at 150°C, reacted for 20 minutes, and cooled to room temperature to obtain a polyrotaxane material.

[0037] Test Example 1 Texture Analysis The polyrotaxane material obtained in Example 1 was subjected to electron microscope scanning and spectral analysis to obtain the following Figure 1 、 Figure 2 The electron microscope scanning diagram and spectrum analysis diagram shown in FIG; Among them, Figure 1 (a) is lipoic acid magnified 1000 times. Figure 1 (b) is a 1000-fold magnification of cyclodextrin polyrotaxane. Figure 1 (c) Polyrotaxane material magnified 5000 times; Figure 2 (a) is the Raman spectrum, Figure 2 (b) Fourier transform infrared spectroscopy and Figure 2 (c) X-ray diffraction spectra. The figure shows that both lipoic acid and cyclodextrin polyrotaxanes were powdery materials before deep eutectic processing. After deep eutectic processing, the prepared polyrotaxane material exhibited a smooth surface due to hydrogen bonding interactions and good dispersion of the polyrotaxane in the lipoic acid, demonstrating successful processing. Raman spectroscopy confirmed that lipoic acid and cyclodextrin polyrotaxane were successfully converted into polyrotaxane materials using the deep eutectic system. Fourier transform infrared spectroscopy confirmed that lipoic acid and cyclodextrin polyrotaxanes were processed through hydrogen bonding interactions. X-ray diffraction spectroscopy confirmed that the interaction between lipoic acid and polyrotaxane resulted in the successful dispersion of the polyrotaxane within the polyrotaxane material, further confirming successful processing.

[0038] Test Example 2 Recovery Experiment Experimental methods 0.8 ml of the polyrotaxane material described in Example 2 was added to 10 ml of ultrapure water and shaken for 2 minutes. The mixture was centrifuged at 8000 rpm for 2 minutes, the supernatant was poured out, and the mixture was washed three times with 20 ml of ultrapure water. The mixture was then freeze-dried at -80 degrees Celsius for 24 hours to obtain the recovered polyrotaxane.

[0039] 0.3 g of the polyrotaxane material described in Example 3 was taken separately and placed in 6 ml of N,N-dimethylformamide solution, heated to 150 degrees Celsius, stirred for 1 to 3 hours, and then waited for the solution to cool, 20 ml of ultrapure water was added, and vigorously shaken for 2 minutes. The mixed solution was then centrifuged at 8000 rpm for 2 minutes, the supernatant was poured out, and then washed three times with 20 ml of ultrapure water, and then freeze-dried at -80 degrees Celsius for 24 hours to obtain the recovered polyrotaxane.

[0040] Figure 3 is the polyrotaxane recovered in Example 3, wherein Figure 3 (a) is an optical photograph of the polyrotaxane recovery process. Figure 3 (b) NMR spectrum of recovered polyrotaxane, Figure 3 (c) is the X-ray diffraction spectrum of the recovered polyrotaxane. Figure 3 (d) Fourier transform infrared spectrum of the recovered polyrotaxane. These results demonstrate that the chemical properties of the polyrotaxane remain unchanged after melt processing using the deep eutectic system, demonstrating the feasibility of deep eutectic melt processing of polyrotaxanes. Figure 4 This is the nuclear magnetic resonance spectrum of the polyrotaxane recovered in Example 2. This demonstrates the stability of the polyrotaxane in the deep eutectic system.

[0041] Test Example 3 Performance Test The tensile and adhesive properties of the polyrotaxane materials obtained in Examples 3 and 4 at different mass fractions were tested; specifically: Tensile Properties: Uniaxial tensile tests were performed at room temperature using an ETM101B universal testing machine (WANCE, China). The tensile rate was set at 10 mm / min unless otherwise specified. Hydrogel samples were prepared in a dumbbell shape (Type 2, GB / T 528–1998) with a 10 mm gap between the grips.

[0042] Adhesion Performance: Adhesion testing was performed using the lap shear method on an ETM101B universal testing machine (WanCe, China) at a speed of 30 mm / min. All samples were sandwiched between two pieces of wood, PMAA, and iron. The wood, PMAA, and iron were stretched, and the maximum tensile force was recorded when cohesive or adhesive failure occurred. The tensile force at break was divided by the area of ​​the PTA material to obtain the adhesion strength.

[0043] Experimental results and analysis: Figure 5 、 Figure 6 As shown, the addition of polyrotaxanes to elastomers and adhesives can effectively enhance their performance. Specifically, for elastomers, the addition of polyrotaxanes allows for comprehensive and optimal control of the material's tensile deformation, tensile strength, toughness, and elastic modulus, overcoming the limitations of traditional filler materials. For adhesives, the addition of polyrotaxanes can effectively enhance adhesion, expanding their application scenarios.

[0044] At this point, those skilled in the art will recognize that, although the embodiments of the present invention have been shown and described in detail herein, many other variations or modifications consistent with the principles of the present invention may be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and deemed to cover all such other variations or modifications.

Claims

1. A method for preparing a polyrotaxane material based on a deep eutectic system, characterized in that: include: 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 thioctic acid or citric acid-choline chloride.

2. The preparation method according to claim 1, characterized in that When the organic acid is thioctic acid, the amount of thioctic acid added to 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 to 0.2 g of cyclodextrin polyrotaxane is ≥83 mmol and the amount of choline chloride added to 0.2 g of cyclodextrin polyrotaxane is ≥14 mmol.

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

4. The preparation method according to claim 1, characterized in that A cross-linking agent may be added to the deep eutectic system and then melted to form a polyrotaxane material.

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

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

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

8. Use of the polyrotaxane material according to claim 7 as an elastomeric material in the preparation of films, coatings, or bonding and coating.

Images