Ultraviolet absorptive cellulose-based thermoplastic elastomer and preparation method thereof

Abstract

The invention belongs to the field of high polymer materials, and particularly relates to a cellulose-based thermoplastic elastomer with ultraviolet absorption performance and a preparation method thereof.The preparation method comprises the following steps that cellulose and 2-bromoisobutyryl bromide react in ionic liquid, and brominated cellulose is obtained; in the presence of triethylamine, lauryl mercaptan and carbon disulfide, brominated cellulose reacts in a solvent dimethyl sulfoxide to obtain the cellulose macroinitiator. The preparation method comprises the following steps: under the action of a catalyst azodiisobutyronitrile, carrying out reversible addition-fragmentation chain transfer polymerization reaction on a cellulose macromolecular chain transfer agent, an ethylhexyl acrylate monomer and an acrylic acid vanillin monomer in a solvent N, N-dimethylformamide to obtain cellulose-g-(ethylhexyl acrylate copolymerized acrylic acid vanillin); according to the invention, cellulose is used as a main chain, and a copolymer (namely poly (ethylhexyl acrylate-co-acrylic acid vanillin)) side chain is grafted, so that the obtained elastomer has excellent elasticity and strength performance. Meanwhile, the material has a certain ultraviolet absorption function, so that the material has certain application potential in the field of delaying light aging, color fading and yellowing functions.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials, specifically relating to a thermoplastic elastomer based on cellulose and possessing ultraviolet absorption properties, and its preparation method. Background Technology

[0002] Elastomers are a crucial component of polymer materials, widely used in automotive, construction, energy manufacturing, and medical fields. While thermosetting elastomers (such as traditional rubber) dominate the market, thermoplastic elastomers (TPEs) are experiencing rapid growth. Global demand for elastomers is increasing daily. Because TPEs combine the elasticity of rubber with the processability of plastics, they not only serve as substitutes for traditional rubber materials in certain applications but also solve the processing challenges of elastomers. From a microstructural perspective, TPEs consist of soft segments in a rubber phase and hard segments in a reinforcing phase. The soft segments, with their low glass transition temperature, provide flexibility as the matrix, while the hard segments, as the reinforcing phase, impart mechanical strength. Their synergistic effect gives the material its elasticity. The processability of TPEs can be achieved by heating and melting the hard segments in the polymer. This has led to extensive research into emerging processing methods for TPEs, such as 3D printing, 4D printing, and electrospinning, greatly expanding their application areas.

[0003] With the development of science and technology and synthetic techniques, TPEs are evolving towards high performance, functionalization, sustainability, and deeper and broader applications. In modern society, with the increasing depletion of fossil resources, bio-based polymers with renewable, biodegradable, and biocompatible properties are gaining popularity. The combination of elastomers and renewable resources makes it possible to prepare novel bio-based elastomers with controllable properties, and significant efforts are being made to design sustainable elastomer polymer materials containing monomers from various biological sources and components with specific functions. The rational and effective utilization of biological resources can alleviate the energy crisis to some extent. Cellulose, as the most abundant natural polymer, has been the subject of much research. Cellulose molecules contain numerous hydrogen bonds and have a dense crystalline structure. Modification can improve its solubility in common solvents, enabling its widespread application in graft polymerization research. Graft modification of cellulose can be carried out through three methods: "Grafting-from," "Grafting-to," and "Grafting-through." By designing molecules to obtain TPEs with specific functions, we can proceed from several aspects, including introducing dynamic covalent bonds and functionalized components, developing bio-based raw materials, and developing biodegradable TPEs. Patent CN 111187385 B discloses a cellulose-based bottle-brush-shaped thermoplastic elastomer and its preparation method. Specifically, cellulose and 2-bromoisobutyryl bromide are reacted in an ionic liquid to obtain cellulose bromide. Under the action of cuprous bromide and pyridine, cellulose bromide is used as a macromolecular initiator to initiate the atom transfer radical polymerization of butyl acrylate monomers to obtain cellulose-g-polybutyl acrylate. Then, in the presence of cuprous chloride and N,N,N,N,N-pentamethyldiethylenetriamine, cellulose-g-polybutyl acrylate is used as a macromolecular initiator to initiate the atom transfer radical polymerization of methyl methacrylate monomers to obtain the cellulose-based bottle-brush-shaped thermoplastic elastomer.

[0004] While existing thermoplastic elastomers possess high mechanical properties, ultraviolet (UV) radiation often causes irreversible damage during actual use. Sunlight's UV rays can trigger oxidation reactions in polymer materials, leading to cracking, brittleness, and decreased strength. UV rays also damage pigments and dyes within the material, causing fading and yellowing. However, materials with UV absorption properties can efficiently absorb harmful UV rays, converting them into relatively harmless heat energy, thereby slowing down the photoaging process. Therefore, preparing elastomers with UV absorption capabilities through chemical modification has the potential to improve product durability and lifespan. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies and solve at least one of the technical problems mentioned in the background art, this invention provides a thermoplastic elastomer with ultraviolet absorption function and a method for preparing the same. The cellulose-based thermoplastic elastomer provided by this invention exhibits excellent elasticity and ultraviolet absorption properties.

[0006] The technical solution adopted by this invention to solve its technical problem is as follows: A method for preparing a cellulose-based thermoplastic elastomer with ultraviolet absorption properties, as described in this invention, includes the following steps: S1. Cellulose and 2-bromoisobutyryl bromide are reacted in an ionic liquid to obtain cellulose bromide; S2. In the presence of triethylamine, dodecyl mercaptan, and carbon disulfide, cellulose bromide is reacted in the solvent dimethyl sulfoxide to obtain a cellulose macromolecular initiator.

[0007] S3. Under the action of the catalyst azobisisobutyronitrile, cellulose macromolecular chain transfer agent, ethylhexyl acrylate monomer, and vanillin acrylate monomer are subjected to a reversible addition-fragmentation chain transfer polymerization reaction in the solvent N,N-dimethylformamide to obtain cellulose-g-(ethylhexyl acrylate copolyvanillin acrylate).

[0008] As a further technical solution of the present invention: in S1, the mass ratio of cellulose to ionic liquid is 1:25; the mass ratio of cellulose to 2-bromoisobutyryl bromide is 1:7.12.

[0009] As a further technical solution of the present invention: in S1, the cellulose is microcrystalline cellulose; the ionic liquid is 1-allyl-3-methylimidazolium chloride.

[0010] As a further technical solution of the present invention: in S1, the reaction temperature is room temperature and the reaction time is 36h.

[0011] As a further technical solution of the present invention: in S2, the mass ratio of cellulose bromide, triethylamine, dodecyl mercaptan, and carbon disulfide is 1:0.35:0.7:0.8.

[0012] As a further technical solution of the present invention: in S2, the reaction temperature is 40°C. o C, the time is 12 hours.

[0013] As a further technical solution of the present invention: in S3, the mass ratio of catalyst to cellulose macromolecular chain transfer agent is 0.82:60; the mass ratio of cellulose macromolecular chain transfer agent, ethylhexyl acrylate and vanillin acrylate is 1:42-65:34-56.

[0014] As a further technical solution of the present invention: in S3, the polymerization reaction temperature is 80°C. oC, the time is 20~24h.

[0015] A thermoplastic elastomer based on cellulose and possessing ultraviolet absorption properties has the structure shown in formula (1): (1) in, Cellulose is a microcrystalline cellulose framework unit; The degree of polymerization of the ethylhexyl polyacrylate structural unit is ≥1; The degree of polymerization y of the polyacrylic acid vanillin structural unit is ≥1.

[0016] As a further technical solution of the present invention: x is 40-160, and y is 8-96.

[0017] The beneficial effects of this invention are as follows: 1. The present invention provides a cellulose-based bottle brush-shaped thermoplastic elastomer having the above-mentioned thermoplastic elastomer structural formula, with cellulose as the main chain and grafted copolymer (i.e., polyethylhexyl acrylate-co-vanillin acrylate) side chains, so that the resulting elastomer has excellent elasticity and strength properties, and also has certain ultraviolet absorption properties.

[0018] 2. This invention provides a method for preparing the above-mentioned cellulose-based bottle brush-shaped thermoplastic elastomer, which combines biomass cellulose with organic molecules to form a thermoplastic elastomer. Firstly, cellulose molecules have numerous hydrogen bonds within and between molecular chains, making them difficult to dissolve in organic solvents for subsequent chemical reactions. This invention uses 2-bromoisobutyryl bromide to modify cellulose in an ionic liquid, and further modifies the brominated cellulose in the presence of triethylamine, dodecyl mercaptan, and carbon disulfide to promote subsequent graft polymerization reactions.

[0019] 3. Experimental results show that the thermoplastic elastomer prepared by this invention has an elongation at break of over 620% and a strength of over 3.8 MPa; it also has good ultraviolet absorption capacity. Attached Figure Description

[0020] The invention will now be further described with reference to the accompanying drawings.

[0021] Figure 1 This is the 1H NMR spectrum of cellulose bromide of the present invention; Figure 2 This is the 1H NMR spectrum of the cellulose macromolecular chain transfer agent of the present invention; Figure 3 The 1H NMR spectrum of the cellulose-g-poly(ethylhexyl acrylate-co-vanillin acrylate) product of Example 1 of this invention is shown below. Figure 4The 1H NMR spectrum of cellulose-g-ethylhexyl polyacrylate, Comparative Example 1 of this invention; Figure 5 The infrared spectra of cellulose, cellulose bromide, and cellulose macromolecular chain transfer agent of the present invention are shown below. Figure 6 The infrared spectrum of the product described in Example 1 of this invention; Figure 7 These are monotonic tensile test diagrams of the products described in Embodiments 1, 2, 3, and 4 of this invention; Figure 8 This is a cyclic tensile test diagram of the cellulose-g-poly(ethylhexyl acrylate-co-vanillin acrylate)1 product of Example 1 of the present invention; Figure 9 This is a cyclic tensile test diagram of the cellulose-g-poly(ethylhexyl acrylate-co-vanillin acrylate)2 product of Example 2 of the present invention; Figure 10 This is a cyclic tensile test diagram of the cellulose-g-poly(ethylhexyl acrylate-co-vanillin acrylate)3 product of Example 3 of the present invention; Figure 11 This is a cyclic tensile test diagram of the cellulose-g-poly(ethylhexyl acrylate-co-vanillin acrylate)4 product of Example 4 of the present invention; Figure 12 This is an AFM height map of the cellulose-g-poly(ethylhexyl acrylate-co-vanillin acrylate)1 product of Example 1 of the present invention; Figure 13 The AFM phase diagram of the cellulose-g-poly(ethylhexyl acrylate-co-vanillin acrylate)1 product of Example 1 of this invention; Figure 14 This is an AFM height map of the cellulose-g-poly(ethylhexyl acrylate-co-vanillin acrylate)2 product of Example 2 of the present invention; Figure 15 The AFM phase diagram of the cellulose-g-poly(ethylhexyl acrylate-co-vanillin acrylate)2 product of Example 2 of the present invention is shown below. Figure 16 This is an AFM height diagram of the cellulose-g-poly(ethylhexyl acrylate-co-vanillin acrylate)3 product of Example 3 of the present invention; Figure 17 The AFM phase diagram of the cellulose-g-poly(ethylhexyl acrylate-co-vanillin acrylate)3 product of Example 3 of the present invention is shown below. Figure 18 This is an AFM height diagram of the cellulose-g-poly(ethylhexyl acrylate-co-vanillin acrylate)4 product of Example 4 of the present invention.

[0022] Figure 19 The AFM phase diagram of the cellulose-g-poly(ethylhexyl acrylate-co-vanillin acrylate)4 product of Example 4 of this invention; Figure 20 The ultraviolet absorption spectra of the cellulose-g-poly(ethylhexyl acrylate-co-vanillin acrylate) product of Example 1 and the cellulose-g-polyethylhexyl acrylate of Comparative Example 1 are shown. Detailed Implementation

[0023] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0024] Example 1 The method for preparing a cellulose-based thermoplastic elastomer with ultraviolet absorption properties according to an embodiment of the present invention includes the following steps: Preparation of cellulose bromide Take 1 g of dried microcrystalline cellulose and 25 g of 1-allyl-3-methylimidazolium chloride, add them to a round-bottom flask, evacuate, and stir until homogeneous at 80 °C. Then add 12 mL of N,N-dimethylformamide and stir until the microcrystalline cellulose is completely dissolved, obtaining a homogeneous and clear mixed solution. Transfer to an ice-water bath, add 7.12 g of 2-bromoisobutyryl bromide dropwise, and then react at room temperature for 36 h. After the reaction is complete, slowly pour the reaction solution into pure water to precipitate and wash three times. The resulting white solid product is dried in a vacuum oven at 50 °C for 24 h to obtain the cellulose initiator, i.e., cellulose bromide.

[0025] Preparation of cellulose macromolecular chain transfer agents 1 g of cellulose bromide was dissolved in 10 mL of dimethyl sulfoxide and added to a round-bottom flask. The solution was stirred and dissolved at 60 °C. 0.35 g of triethylamine and 0.7 g of dodecyl mercaptan were dissolved in a small beaker containing 5 mL of dimethyl sulfoxide. The mixture was stirred at room temperature for 30 min, then 0.8 g of carbon disulfide was added, and stirring was continued for another 20 min to obtain a mixed solution. This mixed solution was added to a round-bottom flask containing cellulose bromide and stirred at 40 °C for 12 h. After the reaction was complete, the reaction solution was slowly poured into pure water to precipitate and wash three times. The resulting white solid product was dried in a vacuum oven at 40 °C for 24 h to obtain the cellulose macromolecular chain transfer agent.

[0026] Preparation of cellulose-g-poly(ethylhexyl acrylate-co-vanillin acrylate)1 60 mg of cellulose macromolecular chain transfer agent was dissolved in 20 mL of N,N-dimethylformamide, followed by the addition of 5.06 g of ethylhexyl acrylate, 4.635 g of vanillin acrylate, and 0.82 mg of azobisisobutyronitrile. The mixture was degassed using a freeze-thaw cycle in liquid nitrogen three times. The reaction was then carried out at 80 °C for 24 h. After the reaction, the reaction solution was slowly poured into water / methanol and washed three times to remove the precipitate. The resulting white product was dried in a vacuum oven at 60 °C for 24 h to obtain cellulose-g-poly(ethylhexyl acrylate-co-vanillin acrylate)1.

[0027] Example 2 The method for preparing a vanillin-containing thermoplastic elastomer according to an embodiment of the present invention differs from that in Example 1 above in the preparation of cellulose-g-poly(ethylhexyl acrylate-co-vanillin acrylate) 1. The specific preparation process is as follows: 60 mg of cellulose macromolecular chain transfer agent was dissolved in 20 mL of N,N-dimethylformamide, followed by the addition of 5.29 g of ethylhexyl acrylate, 4.38 g of vanillin acrylate, and 0.82 mg of azobisisobutyronitrile. The mixture was degassed using a freeze-thaw cycle in liquid nitrogen three times. The reaction was then carried out at 80 °C for 24 h. After the reaction, the reaction solution was slowly poured into water / methanol to precipitate and wash three times. The resulting white product was dried in a vacuum oven at 60 °C for 24 h to obtain cellulose-g-poly(ethylhexyl acrylate-co-vanillin acrylate)2.

[0028] Example 3 The method for preparing a vanillin-containing thermoplastic elastomer according to an embodiment of the present invention differs from that in Example 1 above in the preparation of cellulose-g-poly(ethylhexyl acrylate-co-vanillin acrylate) 1. The specific preparation process is as follows: 60 mg of cellulose macromolecular chain transfer agent was dissolved in 20 mL of N,N-dimethylformamide, followed by the addition of 5.52 g of ethylhexyl acrylate, 4.12 g of vanillin acrylate, and 0.82 mg of azobisisobutyronitrile. The mixture was degassed using a freeze-thaw cycle in liquid nitrogen three times. The reaction was then carried out at 80 °C for 24 h. After the reaction, the reaction solution was slowly poured into water / methanol and washed three times to remove the precipitate. The resulting white product was dried in a vacuum oven at 60 °C for 24 h to obtain cellulose-g-poly(ethylhexyl acrylate-co-vanillin acrylate)3.

[0029] Example 4 The method for preparing a vanillin-containing thermoplastic elastomer according to an embodiment of the present invention differs from that in Example 1 above in the preparation of cellulose-g-poly(ethylhexyl acrylate-co-vanillin acrylate) 1. The specific preparation process is as follows: 60 mg of cellulose macromolecular chain transfer agent was dissolved in 20 mL of N,N-dimethylformamide, followed by the addition of 5.75 g of ethylhexyl acrylate, 3.86 g of vanillin acrylate, and 0.82 mg of azobisisobutyronitrile. The mixture was degassed using a freeze-thaw cycle in liquid nitrogen three times. The reaction was then carried out at 80 °C for 24 h. After the reaction, the reaction solution was slowly poured into water / methanol to precipitate and wash three times. The resulting white product was dried in a vacuum oven at 60 °C for 24 h to obtain cellulose-g-poly(ethylhexyl acrylate-co-vanillin acrylate)4.

[0030] The cellulose-based thermoplastic elastomers prepared by the methods in Examples 1-4 above have the structure shown in formula (1): (1) in, Cellulose is a microcrystalline cellulose framework unit; The degree of polymerization of the ethylhexyl polyacrylate structural unit is ≥1; The degree of polymerization y of the vanillin structural unit of polyacrylic acid is ≥1; Preferably, x is 40~160 and y is 8~96.

[0031] Comparative Example 1 The method for preparing a thermoplastic elastomer according to the comparative example of the present invention differs from that in Example 1 above in the preparation of cellulose-g-poly(ethylhexyl acrylate-co-vanillin acrylate) 1, and the specific preparation process is as follows: 60 mg of cellulose macromolecular chain transfer agent was dissolved in 20 mL of N,N-dimethylformamide, followed by the addition of 5.06 g of ethylhexyl acrylate and 0.82 mg of azobisisobutyronitrile. The mixture was then subjected to three freeze-thaw cycles in liquid nitrogen for degassing. The reaction was then carried out at 80 °C for 24 h. After the reaction, the reaction solution was slowly poured into water / methanol and washed three times to remove the precipitate. The resulting white product was dried in a vacuum oven at 60 °C for 24 h to obtain cellulose-g-ethylhexyl polyacrylate.

[0032] Performance testing Figure 1 The image shows the 1H NMR spectrum of cellulose bromide from Example 1. Position 1 in the image represents the chemical shift of the hydrogen atom on the -CH3 group of the 2-bromoisobutyryl group, which strongly proves the correct synthesis of the product.

[0033] Figure 2 The image shows the 1H NMR spectrum of the cellulose macromolecular chain transfer agent in Example 1. At positions a and b, the chemical shifts of the hydrogen atoms in the -CH3 group of the 2-bromoisobutyryl group and the -CH3 group of the dodecylthiol group, respectively, strongly confirming the correct synthesis of the product.

[0034] Figure 3 The figure shows the 1H NMR spectrum of the cellulose-g-poly(n-butyl acrylate-co-vanillin acrylate) product of Example 1. In the figure, m and n represent the chemical shift of the hydrogen atom on the aldehyde group in vanillin acrylate and the chemical shift of the -CH3 group in ethylhexyl acrylate, respectively.

[0035] Figure 4 The figure shows the 1H NMR spectrum of the cellulose-g-ethylhexyl acrylate product of Comparative Example 1. In the figure, f and i represent the chemical shifts of the hydrogen on the -CH3 group of ethylhexyl acrylate, and c represents the chemical shift of the hydrogen on the -CH2 group directly attached to the ester group.

[0036] Figure 5 The figures show the infrared spectra of cellulose, cellulose bromide products, and cellulose macromolecular chain transfer agent products. The infrared spectrum of cellulose bromide from Example 1 shows a peak at 1734 cm⁻¹. -1 The carbonyl peak represents the carbonyl group on brominated cellulose, and compared with the infrared spectrum of cellulose, it is located in the range of 3037-3674 cm⁻¹. -1 The intensity of the hydroxyl peak at 2927 cm⁻¹ decreased significantly, strongly proving the successful synthesis of cellulose bromide; the infrared spectrum corresponding to the cellulose macromolecular chain transfer agent product in the figure shows a peak at 2927 cm⁻¹. -1 2852cm -1 The -CH3 and -CH peaks at the position strongly prove the synthesis of the cellulose macromolecular chain transfer agent.

[0037] Figure 6 The infrared spectrum of the cellulose-g-poly(n-butyl acrylate-co-vanillin acrylate) product from Example 1 is shown in the figure, from 400 to 842 cm⁻¹. -1 The fingerprint region of the benzene ring strongly supports the synthesis of cellulose-g-poly(ethylhexyl acrylate-co-vanillin acrylate).

[0038] Figure 7 The tensile test images are for the cellulose-g-poly(n-butyl acrylate-co-vanillin acrylate) products of Examples 1, 2, 3, and 4. The cellulose-g-poly(n-butyl acrylate-co-vanillin acrylate) products of Examples 1, 2, 3, and 4 were cut into dumbbell-shaped strips with a thickness of approximately 0.35 mm, a width of 2 mm, and a length of 35 mm for tensile testing. The results are as follows. Figure 3As shown, the product obtained in Example 1 has a fracture strength of 3.8 MPa, a Young's modulus of 50.7 MPa, and an elongation at break of 320%. The product obtained in Example 2 has a fracture strength of 3.5 MPa, a Young's modulus of 19.6 MPa, and an elongation at break of 475%. The product obtained in Example 3 has a fracture strength of 2.7 MPa, a Young's modulus of 12.5 MPa, and an elongation at break of 552%. The product obtained in Example 4 has a fracture strength of 1.4 MPa, a Young's modulus of 4.4 MPa, and an elongation at break of 620%. This indicates that the material obtained by the present invention has excellent ductility and mechanical properties.

[0039] Cyclic tensile tests were performed on the dumbbell-shaped spline described in Example 1, and the results are as follows: Figure 8 As shown, Figure 8 The image shows the cyclic tensile test results of the product obtained in Example 1. It can be seen that in the stress-strain curves of the obtained product during the cyclic tensile process, the maximum strain values ​​for each tensile cycle are 40%, 80%, 120%, 160%, 200%, 240%, 280%, 320%, and 360%, respectively.

[0040] Cyclic tensile tests were performed on the dumbbell-shaped spline described in Example 2, and the results are as follows: Figure 9 As shown, Figure 9 The image shows the cyclic tensile test results of the product obtained in Example 2. It can be seen that in the stress-strain curves of the obtained product during the cyclic tensile process, the maximum strain values ​​for each tensile cycle are 40%, 80%, 120%, 160%, 200%, 240%, 280%, 320%, and 360%, respectively.

[0041] Cyclic tensile tests were performed on the dumbbell-shaped spline described in Example 3, and the results are as follows: Figure 10 As shown, Figure 10 The image shows the cyclic tensile test results of the product obtained in Example 3. It can be seen that in the stress-strain curves of the obtained product during the cyclic tensile process, the maximum strain values ​​for each tensile cycle are 40%, 80%, 120%, 160%, 200%, 240%, 280%, 320%, 360%, and 400%, respectively.

[0042] Cyclic tensile tests were performed on the dumbbell-shaped spline described in Example 4, and the results are as follows: Figure 11 As shown, Figure 11 The image shows the cyclic tensile test results of the product obtained in Example 4. It can be seen that in the stress-strain curves of the obtained product during the cyclic tensile process, the maximum strain values ​​for each tensile cycle are 40%, 80%, 120%, 160%, 200%, 240%, 280%, 320%, 360%, and 400%, respectively.

[0043] The product obtained in Example 1 was tested using atomic force microscopy, and the results are as follows: Figure 12 and Figure 13 As shown, Figure 12 This is the AFM height map of Example 1. Figure 13 This is the AFM phase diagram for Example 1. (Combined with...) Figure 12 and Figure 13 In Example 1, the sample exhibited a uniform morphology with no obvious microphase separation structure.

[0044] The product obtained in Example 2 was subjected to atomic force microscopy testing, and the results are as follows: Figure 14 and Figure 15 As shown, Figure 14 This is the AFM height map for Example 2. Figure 15 This is the AFM phase diagram for Example 2. (Combined with...) Figure 14 and Figure 15 In Example 2, the sample exhibited a uniform morphology with no obvious microphase separation structure.

[0045] The product obtained in Example 3 was subjected to atomic force microscopy testing, and the results are as follows: Figure 16 and Figure 17 As shown, Figure 16 This is the AFM height map for Example 3. Figure 17 This is the AFM phase diagram for Example 3. (Combined with...) Figure 16 and Figure 17 In Example 3, the sample exhibited a uniform morphology with no obvious microphase separation structure.

[0046] The product obtained in Example 4 was subjected to atomic force microscopy testing, and the results are as follows: Figure 18 and Figure 19 As shown, Figure 18 This is the AFM height map for Example 4. Figure 19 This is the AFM phase diagram for Example 4. (Combined with...) Figure 18 and Figure 19 In Example 4, the sample exhibited a uniform morphology with no obvious microphase separation structure.

[0047] The products obtained in Example 1 and Comparative Example 1 were subjected to ultraviolet absorption spectroscopy tests. Comparative Example 1 is a common cellulose-based brush-like thermoplastic elastomer. The results are as follows: Figure 20 As shown, Figure 20 The ultraviolet absorption spectra of Example 1 and Comparative Example 1 show that, compared with ordinary cellulose elastomers, the cellulose elastomers of the present invention, such as those in Example 1, have obvious ultraviolet absorption peaks in the wavelength range of 200 nm to 400 nm.

[0048] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a cellulose-based thermoplastic elastomer with ultraviolet absorption properties, characterized in that: Includes the following steps: S1. Cellulose and 2-bromoisobutyryl bromide are reacted in an ionic liquid to obtain cellulose bromide; S2. In the presence of triethylamine, dodecyl mercaptan, and carbon disulfide, cellulose bromide is reacted in the solvent dimethyl sulfoxide to obtain a cellulose macromolecular initiator. S3. Under the action of the catalyst azobisisobutyronitrile, cellulose macromolecular chain transfer agent, ethylhexyl acrylate monomer, and vanillin acrylate monomer are subjected to a reversible addition-fragmentation chain transfer polymerization reaction in the solvent N,N-dimethylformamide to obtain cellulose-g-(ethylhexyl acrylate copolyvanillin acrylate).

2. The method for preparing a cellulose-based thermoplastic elastomer with ultraviolet absorption properties according to claim 1, characterized in that: In S1, the mass ratio of cellulose to ionic liquid is 1:25; the mass ratio of cellulose to 2-bromoisobutyryl bromide is 1:7.

12.

3. The method for preparing a cellulose-based thermoplastic elastomer with ultraviolet absorption properties according to claim 1, characterized in that: In S1, the cellulose is microcrystalline cellulose; the ionic liquid is 1-allyl-3-methylimidazolium chloride.

4. The method for preparing a cellulose-based thermoplastic elastomer with ultraviolet absorption properties according to claim 1, characterized in that: In S1, the reaction temperature is room temperature and the reaction time is 36 hours.

5. The method for preparing a cellulose-based thermoplastic elastomer with ultraviolet absorption properties according to claim 1, characterized in that: In S2, the mass ratio of cellulose bromide, triethylamine, dodecyl mercaptan, and carbon disulfide is 1:0.35:0.7:0.

8.

6. The method for preparing a cellulose-based thermoplastic elastomer with ultraviolet absorption properties according to claim 1, characterized in that: In S2, the reaction temperature is 40°C. o C, the time is 12 hours.

7. The method for preparing a cellulose-based thermoplastic elastomer with ultraviolet absorption properties according to claim 1, characterized in that: In S3, the mass ratio of catalyst to cellulose macromolecular chain transfer agent is 0.82:60; the mass ratio of cellulose macromolecular chain transfer agent, ethylhexyl acrylate and vanillin acrylate is 1:42-65:34-56.

8. The method for preparing a cellulose-based thermoplastic elastomer with ultraviolet absorption properties according to claim 1, characterized in that: In S3, the polymerization reaction temperature is 80°C. o C, the time is 20-24 hours.

9. A cellulose-based thermoplastic elastomer prepared by the method according to any one of claims 1-8, characterized in that: The cellulose-based thermoplastic elastomer has the structure shown in formula (1): （1） in, Cellulose is a microcrystalline cellulose framework unit; The degree of polymerization of the ethylhexyl polyacrylate structural unit is ≥1; The degree of polymerization y of the polyacrylic acid vanillin structural unit is ≥1.

10. A thermoplastic elastomer based on cellulose and possessing ultraviolet absorption properties according to claim 9, characterized in that: x is 40-160, y is 8-96.

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