Polyurethane elastomer material with shape memory and self-healing characteristics as well as preparation method and application thereof

Abstract

The invention discloses a polyurethane elastomer material with shape memory and self-healing characteristics and a preparation method thereof. The polyurethane elastomer material is prepared by taking diisocyanate, polytetrahydrofuran 2000, 2-ureido-4-pyrimidone and 7-(2-hydroxyethoxy)-4-methyl-2H-chromene-2-ketone as raw materials and taking an organic tin compound as a catalyst through polymerization. The preparation method disclosed by the invention is simple and easy to implement, and the prepared polyurethane elastomer material shows excellent shape memory performance under thermal stimulation, can realize reversible photo-crosslinking reaction and also shows excellent self-healing capability. Due to the advantages, the polyurethane copolymer material has a wide application prospect in the field of intelligent materials.

Description

Technical Field

[0001] The invention relates to a polyurethane elastomer material with shape memory and self-healing properties and used as a conductive polymer matrix, a preparation method and application thereof, and belongs to the technical field of polymer materials and their preparation. Background Art

[0002] Most polymer materials require high-temperature molding processes to prepare, and once solidified, they are difficult to reshape, significantly limiting their practical applications. Furthermore, traditional polymers are susceptible to various mechanical damages in complex environments. These minor internal or surface damages are often difficult to detect and repair in a timely manner, reducing the material's lifespan and leading to resource waste. Therefore, endowing polymer materials with multifunctional properties, such as self-healing and programmability, has become an urgent issue to be addressed.

[0003] Polyurethane, a polymer material with excellent performance and adjustable structure, exhibits the unique phenomenon of internal microphase separation, which imparts excellent shape memory properties. Therefore, polyurethane has become an ideal choice for multifunctional polymer matrices. By introducing dynamic, reversible covalent bonds or non-covalent interactions into polyurethane, it is possible to impart the ability to self-heal mechanical damage. Furthermore, polyurethane elastomers can be used as conductive polymer matrices, expanding their application prospects in areas such as flexible electronic devices. Therefore, the development of polyurethane elastomer materials with both shape memory and self-healing properties suitable for conductive polymer matrices is of great significance for improving material performance and broadening their application range. Summary of the Invention

[0004] The purpose of the present invention is to provide a polyurethane elastomer material with shape memory and self-healing properties and used as a conductive polymer matrix, as well as a preparation method and application thereof, so as to solve the problems of low healing efficiency and difficulty in programming of existing polymer functional materials.

[0005] The implementation process of the present invention is as follows: The polyurethane copolymer represented by the following general structural formula,

[0006] Wherein, R is selected from substituted or unsubstituted phenyl, biphenyl, naphthyl, cyclohexyl or xylyl, the substituent is C1~C4 alkyl, C1~C4 alkoxy, halogen or halogenmethyl; n is a positive integer of 2 to 10; x and y are positive integers of 10 to 120 respectively.

[0007] Preferably, n is a positive integer of 2 to 6; x and y are positive integers of 10 to 60 respectively.

[0008] The preparation method of the polyurethane copolymer comprises the following steps: (1) reacting diisocyanate, polytetrahydrofuran and 2-ureido-4-pyrimidone in the presence of an organotin catalyst to obtain a prepolymer; the diisocyanate has a structural formula of OCN-R-NCO, R is selected from substituted or unsubstituted phenyl, biphenyl, naphthyl, cyclohexyl or xylyl, and the substituent is a C1-C4 alkyl, C1-C4 alkoxy, halogen or halogenmethyl; (2) reacting the prepolymer obtained in step (1) with 7-(2-hydroxyethoxy)-4-methyl-2H-chromen-2-one to obtain a crude copolymer product; (3) The crude copolymer obtained in step (2) is added to methanol for purification, and the lower precipitate is collected to obtain the pure polyurethane copolymer.

[0009] In the above step (1), the organic tin catalyst is selected from dibutyltin dineoctanoate, dimethyltin dineoctanoate, methyltin mercaptan, dibutyltin dilaurate, and di-n-octyltin dilaurate.

[0010] In the above step (1), the molar ratio of diisocyanate, polytetrahydrofuran and 2-ureido-4-pyrimidone is 12:(3-5):(4-7).

[0011] In the above step (1), the diisocyanate is selected from: .

[0012] In the above step (2), the molar ratio of diisocyanate to 7-(2-hydroxyethoxy)-4-methyl-2H-chromen-2-one is 12:(1-4). The amount of diisocyanate in step (2) is the same as the amount of diisocyanate used in step (1).

[0013] In the above steps (1) and (2), the reaction temperature is 30-100°C.

[0014] The polyurethane copolymer prepared by the invention has shape memory and self-healing properties and can also be used as a conductive polymer matrix.

[0015] Advantages and positive effects of the present invention: The preparation method of the present invention is simple and easy, and the prepared polyurethane elastomer material exhibits excellent shape memory properties under thermal stimulation. The introduced 7-(2-hydroxyethoxy)-4-methyl-2H-chromen-2-one group can undergo a reversible photocrosslinking reaction under ultraviolet light stimulation. Combined with the reorganization of hydrogen bonds in the material, this imparts excellent self-healing ability to the material, capable of recovering more than 89% of its original tensile strength. In addition, the polyurethane copolymer of the present invention can also serve as a conductive polymer matrix. These advantages give the polyurethane copolymer material of the present invention broad application prospects in the field of smart materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the infrared spectrum of the polyurethane elastomer material prepared in Example 1; Figure 2 This is a thermally programmed image of the polyurethane elastomer material prepared in Example 1; Figure 3 This is an optical microscope photograph of the scratch healing of the polyurethane elastomer material prepared in Example 1; Figure 4 The original stress-strain curve of the polyurethane elastomer material prepared in Example 1 and the stress-strain curve after being cut with a scalpel, irradiated with 365 nm UV light for 2 hours, and self-healed at 80° C. for 4 hours; Figure 5 This is a picture of the polyurethane elastomer material prepared in Example 1 as a conductive polymer matrix. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific examples. It should be understood that the specific examples described herein are only used to explain the content of the present invention and do not constitute a limitation of the present invention. The raw materials or reagents used in the implementation of the present invention can be purchased or prepared by themselves. Example 1

[0018] A polyurethane elastomer material was prepared according to the following reaction formula, wherein x=28, y=14, and n=6.

[0019]

[0020] Step (1): Before the reaction, 0.6 g of polytetrahydrofuran 2000 (0.3 mmol) was vacuum dried in an argon atmosphere for 1 hour to remove moisture. Then, 0.6 g of polytetrahydrofuran 2000, 0.2228 g of isophorone diisocyanate (1 mmol) and 21 mg of 2-ureido-4-pyrimidone (0.5 mmol) were added to a flask and dissolved in 1 ml of nitrogen-dimethylformamide. 20 μl of catalyst dibutyltin dilaurate was added, and the air in the reaction flask was replaced with argon three times. The polymerization reaction was carried out at 75°C for 2 hours.

[0021] Step (2): 9.2 mg of 7-(2-hydroxyethoxy)-4-methyl-2H-chromen-2-one (0.25 mmol) was dissolved in 1 ml of nitrogen-dimethylformamide and added to the above reaction flask. The mixture was stirred at 90°C for 8 hours.

[0022] Step (3): After the reaction is completed, add 1 ml of methanol and stir for 0.5 hours. Then pour the reaction solution into a mold made of tetrafluoroethylene and vacuum dry it for 24 hours to obtain a sample film.

[0023] Figure 1 The infrared spectrum of the prepared polyurethane elastomer material is shown in the figure. Upy is 2-ureido-4-pyrimidinone, PTMEG2000 is a polytetramethylene oxide ether with a molecular weight of 2000, PU-HEOMC is a polyurethane material polymerized with coumarin as the end group, IPDI is isophorone diisocyanate, and HEOMC is coumarin. As can be seen from the figure, the -NCO in the isocyanate and the -OH in the polytetramethylene oxide are at 2245 cm-1, respectively. -1 and 3462 cm -1 The characteristic vibration peaks at 3294 cm-1 and 3394 cm-2 disappeared, and the characteristic vibration peaks of -NH and -C=O of the amide part after isocyanate conversion appeared at 3294 cm-1 respectively. -1 and 1644cm -1 , indicating that the reaction raw materials have been completely converted.

[0024] Figure 2 An image of the thermally programmed polyurethane elastomer material. As shown, the prepared polyurethane elastomer material can be thermally programmed. Its properties can be reprogrammed by heating it above its glass transition temperature and then rapidly cooling it. Upon reheating it above its glass transition temperature, its shape returns to its original state.

[0025] Figure 3 This is an optical microscope photo of the scratch healing of the prepared polyurethane elastomer material. Figure 3 It can be seen that the polyurethane elastomer material prepared in Example 1 has excellent self-healing properties.

[0026] Figure 4 The original stress-strain curve of the prepared polyurethane elastomer material, as well as the stress-strain curve after the sample was cut with a scalpel, irradiated with 365 nm ultraviolet light for 2 hours, and self-healed at 80°C for four hours. The healing efficiency of the completely broken membrane of the prepared UV-assisted self-healing polyurethane elastomer material can reach 89%.

[0027] Figure 5 This image shows a polyurethane elastomer material used as a conductive polymer matrix. After mixing 1 gram of polyurethane with 0.05 grams of carbon nanotubes, the mixture was poured into a mold and dried. The resulting conductive polymer exhibits stable conductivity and self-healing properties. Example 2

[0028] The only difference between this example and Example 1 is that the molar ratio of 7-(2-hydroxyethoxy)-4-methyl-2H-chromen-2-one and 2-ureido-4-pyrimidinone is 1:3, and the rest is exactly the same as Example 1. Example 3

[0029] The only difference between this embodiment and Example 1 is that the molar ratio of 7-(2-hydroxyethoxy)-4-methyl-2H-chromene-2-one and 2-ureido-4-pyrimidone is 3:5. The rest is exactly the same as in Example 1. A polyurethane elastomer material is prepared, wherein x=25, y=14, and n=6. Example 4

[0030] The only difference between this embodiment and embodiment 1 is that the polytetrahydrofuran used is polytetrahydrofuran 1000 and n=3. The rest is exactly the same as embodiment 1. Example 5

[0031] The only difference between this embodiment and embodiment 1 is that the isocyanate used is 4,4'-methylenebis(phenyl isocyanate), and the rest is exactly the same as in embodiment 1. Example 6

[0032] The only difference between this embodiment and embodiment 1 is that the isocyanate used is toluene diisocyanate, and the rest is exactly the same as embodiment 1.

[0033]

[0034] In summary, the present invention significantly endows the material of the present invention with UV-assisted self-healing properties by covalently linking coumarin to the polyurethane material, and also exhibits excellent mechanical properties and environmental stability, and has the potential to serve as a conductive polymer matrix.

[0035] The above is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed in the present invention should be covered by the scope of protection of the present invention.

Claims

1. A polyurethane copolymer, characterized in that The structural formula is, Wherein, R is selected from substituted or unsubstituted phenyl, biphenyl, naphthyl, cyclohexyl or xylyl, the substituent is C1~C4 alkyl, C1~C4 alkoxy, halogen or halogenmethyl; n is a positive integer of 2 to 10; x and y are positive integers of 10 to 120 respectively.

2. The polyurethane copolymer according to claim 1, wherein: n is a positive integer from 2 to 6; x and y are positive integers from 10 to 60 respectively.

3. The method for preparing the polyurethane copolymer according to claim 1, characterized in that The following steps are involved: (1) reacting diisocyanate, polytetrahydrofuran and 2-ureido-4-pyrimidone in the presence of an organotin catalyst to obtain a prepolymer; the diisocyanate has a structural formula of OCN-R-NCO, R is selected from substituted or unsubstituted phenyl, biphenyl, naphthyl, cyclohexyl or xylyl, and the substituent is a C1-C4 alkyl, C1-C4 alkoxy, halogen or halogenmethyl; (2) reacting the prepolymer obtained in step (1) with 7-(2-hydroxyethoxy)-4-methyl-2H-chromen-2-one to obtain a crude copolymer; (3) The crude copolymer obtained in step (2) is added to methanol for purification, and the lower precipitate is collected to obtain the pure polyurethane copolymer.

4. The method for preparing the polyurethane copolymer according to claim 3, wherein: In the above step (1), the organic tin catalyst is selected from dibutyltin dineoctanoate, dimethyltin dineoctanoate, methyltin mercaptan, dibutyltin dilaurate, and di-n-octyltin dilaurate.

5. The method for preparing the polyurethane copolymer according to claim 3, wherein: In the above step (1), the molar ratio of diisocyanate, polytetrahydrofuran and 2-ureido-4-pyrimidone is 12:(3-5):(4-7).

6. The method for preparing the polyurethane copolymer according to claim 3, wherein: In the above step (1), the diisocyanate is selected from one of the following compounds, 。 7. The method for preparing the polyurethane copolymer according to claim 3, wherein: In the above step (2), the molar ratio of diisocyanate to 7-(2-hydroxyethoxy)-4-methyl-2H-chromen-2-one is 12:(1-4).

8. The method for preparing the polyurethane copolymer according to claim 3, wherein: In the above steps (1) and (2), the reaction temperature is 30-100°C.

9. Use of the polyurethane copolymer according to claim 1 as a shape memory material or a self-healing material.

10. Use of the polyurethane copolymer according to claim 1 as a conductive polymer matrix.

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