Self-repairable castor oil-based polyurethane as well as preparation method and application thereof

Abstract

The invention discloses self-repairable castor oil-based polyurethane as well as a preparation method and application thereof. The molecular structure of the castor oil-based polyurethane contains castor oil-based silane (SCO) which is a dual cross-linking agent, and the polyhydroxy structure of castor oil forms internal cross-linking in the synthesis process, so that the mechanical property of the polyurethane is enhanced; a large number of siloxane groups introduced by a CO side chain are hydrolyzed in the film forming process of castor oil-based polyurethane (DSCPU) to form silicon hydroxyl (Si-OH), then the silicon hydroxyl (Si-OH) is condensed to form a Si-O-Si structure, and polysiloxane is formed in the polyurethane to achieve the effect of a reinforcing agent; the double cross-linked structure and the organic-inorganic hybrid structure are superposed, so that the mechanical properties, water resistance, heat resistance and the like of the DSCPU can be effectively enhanced. The preparation method of the castor oil-based polyurethane is simple in process, low in cost and capable of realizing large-scale production, and the prepared polyurethane material can be applied to multiple fields such as biomedical materials, building materials, automobile interior and exterior ornaments, electronic equipment, textiles and coatings.

Description

Technical Field

[0001] The present application relates to the technical field of polymer materials, and in particular to a self-repairable castor oil-based polyurethane, a preparation method and an application thereof. Background Art

[0002] Polyurethane is a widely used polymer material. Due to its excellent properties, such as wear resistance, high mechanical strength, high elasticity, aging resistance, corrosion resistance, etc., it is used in many fields such as furniture, construction, electronics, textiles, and medical treatment. However, polyurethane will inevitably suffer physical or chemical damage during actual use, which will lead to material damage, performance degradation, failure, or even scrapping. These failed and scrapped polyurethanes will inevitably increase energy consumption and environmental pollution.

[0003] The development of self-healing polyurethane is undoubtedly a feasible way to extend its service life and effectively alleviate the energy crisis and environmental pressure. However, most of the intrinsic self-healing polyurethanes are mainly synthesized based on disulfide bonds, diselenide bonds and alkoxyamine structures. Most of the self-healing properties require external stimulation to achieve, such as high temperature heating or long-term light exposure. In contrast, polyurethanes that can be repaired at low temperatures or even room temperature are particularly valuable. Studies have shown that the introduction of a large number of oxime-carbamate groups (also known as oxime-urethane bonds) into the polyurethane structure can give polyurethanes the ability to spontaneously self-heal at room temperature. The principle is that the oxime-urethane bond is a new type of covalent bond with dynamic exchange, which gives polyurethane intrinsic self-healing properties. However, based on current research, the research on self-healing polyurethanes based on oxime-urethane bonds is still in its infancy, and there are mainly two extremes: (1) the self-healing temperature is low, and it can even self-heal at room temperature, but the mechanical properties are poor; (2) the cross-linking density is large, with good mechanical properties, but the self-healing conditions require high requirements. In addition, traditional polyurethanes derived from petrochemical resources do not have renewable properties and do not meet the goal of sustainable development of the polyurethane industry. Currently, the industry prefers to use biomass to prepare bio-based polyurethanes, but bio-based polyurethanes generally have defects such as mechanical properties that are inferior to traditional polyurethanes. Therefore, they need to be hybridized and modified.

[0004] In summary, developing a bio-based polyurethane that can heal under mild conditions has good application prospects. Summary of the invention

[0005] In view of this, the purpose of the present application is to provide a self-repairable castor oil-based polyurethane, a preparation method and an application. The siloxane-modified bio-based polyurethane hybrid material contains a large number of oxime urethane groups that can undergo dynamic reversible cleavage-exchange reactions at room temperature to ensure self-healing efficiency, and at the same time, by introducing castor oil-based silane (SCO) to form a double cross-linking form of internal cross-linking and external cross-linking in the polyurethane, the purpose of surface functionalization of the polyurethane material and enhancing mechanical, water resistance, solvent resistance and other properties is achieved.

[0006] To achieve the above objectives, this application provides the following technical solutions:

[0007] In a first aspect, the present application provides a method for preparing a self-repairable castor oil-based polyurethane, the specific steps of which are:

[0008] The first step is to synthesize castor oil-based silane (SCO);

[0009] In the second step, castor oil-based polyurethane (DSCPU) was prepared by a one-pot method using polycaprolactone (PCL) as the soft segment, isophorone diisocyanate (IPDI) as the hard segment, dimethylglyoxime (DMG) as the chain extender, castor oil-based silane (SCO) obtained in the first step as the crosslinking agent, and mercaptopropyltrimethoxysilane (MPTEM) as the end-capping agent;

[0010] The third step is to pour the castor oil-based polyurethane (DSCPU) obtained in the second step into a spindle-shaped polytetrafluoroethylene mold, dry it, and remove the residual solvent to obtain the self-repairable castor oil-based polyurethane.

[0011] In a second aspect, the present application provides a self-healing castor oil-based polyurethane, which is prepared by the aforementioned preparation method.

[0012] In a third aspect, the present application provides an application of the aforementioned self-repairable castor oil-based polyurethane in the preparation of biomedical materials, electronic devices, textiles, and coating products.

[0013] The self-repairable castor oil-based polyurethane, preparation method and application provided in this application have at least the following beneficial effects compared with the prior art:

[0014] 1. The self-repairable castor oil-based polyurethane provided in the present application contains a dual cross-linking agent, castor oil-based silane (SCO), in its molecular structure. On the one hand, the polyhydroxy structure of castor oil forms internal cross-linking during the synthesis process to enhance the mechanical properties of polyurethane; on the other hand, a large number of siloxane groups introduced into the CO side chain by click chemistry are hydrolyzed to form silanol (Si-OH) during the film formation process of castor oil-based polyurethane (DSCPU), and then condensed to form a Si-O-Si structure, and polysiloxane is formed inside the polyurethane to act as a reinforcing agent; the dual cross-linking structure superimposed on the organic-inorganic hybrid structure can effectively enhance the mechanical properties and water resistance, heat resistance and other properties of DSCPU.

[0015] 2. The self-repairable castor oil-based polyurethane provided in the present application has methoxy groups on the castor oil side chains that easily condense with the -OH on the surface of the matrix to form a strong covalent bond, thereby enhancing adhesion. The introduction of a large amount of polycaprolactone (PCL) as a degradable soft segment into the polyurethane structure is beneficial to fully release the biocompatibility of the polyurethane. At the same time, the inherent water resistance of polycaprolactone (PCL) can also ensure that the polyurethane maintains good water resistance under low cross-linking conditions.

[0016] 3. The self-repairable castor oil-based polyurethane provided in the present application has a large number of dynamic oxime-urethane bonds formed in the molecular structure, providing excellent self-repairing properties.

[0017] 4. The method for preparing the self-repairable castor oil-based polyurethane provided in the present application has a simple process, low cost, and can be mass-produced. The prepared polyurethane material has a wide range of applications and can be used in many fields such as biomedical materials, building materials, automotive interior and exterior trims, electronic equipment, electronic equipment, textiles, coatings, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a diagram of the synthesis mechanism of castor oil-based polyurethane (DSCPU) provided in the examples of this application.

[0019] Figure 2 The figures are diagrams showing the repair effects of the DPU and DSCPU films provided in the embodiments of the present application at room temperature, wherein (a) to (e) are polarizing microscope images of DSCPU films with different DPU and SCO contents before self-repair, and (f) to (j) are polarizing microscope images of the DPU and DSCPU films after self-repair at room temperature.

[0020] Figure 3 These are the cross-sectional repair performance test diagrams of the DSCPU film of the embodiment of the present application, wherein (a) is a colored picture of the fractured portion of the film, (b) is a picture of the fractured portion of the film hung on the wall after being pressed for 1 minute, and (c) is a picture of the DSCPU5 film stretching process.

[0021] Figure 4 The results of three fracture-repair cycles of the DSCPU5 film provided in the examples of the present application.

[0022] Figure 5 This is a diagram of the process of using a hair dryer to repair film scratches on DSCPU5 and DSCPU10 provided in an embodiment of the present application.

[0023] Figure 6 This is a DSCPU5 film welding performance test diagram provided in an embodiment of the present application, wherein (a) is a welding schematic diagram, and (b) is a schematic diagram of the fracture process after welding. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0025] Those skilled in the art will appreciate that, unless otherwise stated, the words "said", "the", "the aforementioned", and "above" used in the text of the present application may also include plural forms. It should be further understood that the wording "comprising" used in the specification of the present application means the presence of the features, steps, and operations, but does not exclude the presence or addition of one or more other features, integers, and steps.

[0026] In the text of this application, the terms "first", "second" and the like are used to distinguish between identical or similar items with substantially the same functions and effects. This is only for the purpose of clearly describing the technical solutions of the embodiments of this application, and shall not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features.

[0027] Those skilled in the art will appreciate that, in the examples of the present application, if no specific conditions are specified, the experiments are carried out under conventional conditions or conditions recommended by the manufacturer, and the reagents or instruments used, if no manufacturer is specified, are conventional products that can be purchased commercially.

[0028] In order to solve the problems of the prior art, a bio-based polyurethane material with certain mechanical properties and self-healing under mild conditions has been developed. The embodiment of the present application innovates on the basis of the prior art and proposes a new molecular structure design of modified polyurethane. Figure 1The synthesis mechanism of castor oil-based polyurethane (DSCPU) with a double cross-linked structure of dynamic oxime-urethane bonds is shown. First, castor oil-based silane (SCO) is prepared quickly and efficiently by click chemistry. Secondly, dimethylglyoxime (DMG) containing two oxime groups is used as a multifunctional small molecule chain extender (to adjust the cross-linking density and provide repairability), polycaprolactone (PCL) is a biodegradable soft segment, and castor oil-based silane (SCO) is a bio-based double cross-linking point to synthesize a new type of bio-based organosiloxane-modified bio-based polyurethane containing a large number of oxime-urethane bonds. The bio-based polyurethane contains a large number of oxime-urethane groups that can undergo dynamic reversible cleavage-exchange reactions at room temperature to ensure its self-healing efficiency. At the same time, by introducing castor oil-based silane (SCO) to form a double cross-linking form of internal cross-linking and external cross-linking in the polyurethane, the purpose of functionalizing the polyurethane surface and enhancing mechanical, water-resistant, solvent-resistant and other properties is achieved.

[0029] Based on this, an embodiment of the present application provides a method for preparing a self-healing castor oil-based polyurethane, and the specific steps are: S1. synthesizing castor oil-based silane (SCO); S2. using polycaprolactone (PCL) as a soft segment, isophorone diisocyanate (IPDI) as a hard segment, dimethylglyoxime (DMG) as a chain extender, and the castor oil-based silane (SCO) obtained in S1 as a cross-linking agent, and preparing castor oil-based polyurethane (DSCPU) by a one-pot method; S3. pouring the castor oil-based polyurethane (DSCPU) obtained in S2 into a spindle-shaped polytetrafluoroethylene mold, drying, and removing residual solvents to obtain the self-healing castor oil-based polyurethane.

[0030] In some embodiments, in the above S1, the specific steps for synthesizing castor oil-based silane (SCO) are: (1) adding castor oil (CO), mercaptopropyltrimethoxysilane and an appropriate amount of photoinitiator into a sample bottle filled with inert gas to obtain a first mixture; (2) placing the sample bottle containing the first mixture under ultraviolet light for reaction to obtain castor oil-based silane (SCO) after overnight.

[0031] In certain embodiments, in step (1), the inert gas is argon.

[0032] In certain preferred embodiments, in step (1), the photoinitiator is dimethyl benzoate, and its mass proportion in the first mixture is 1% to 4%.

[0033] In some embodiments, in step (2), the wavelength of the ultraviolet light is 300-400 nm, and the light intensity is 1200-1500 mW.

[0034] In certain embodiments, in the above S2, the specific steps of preparing the castor oil-based polyurethane (DSCPU) are: mixing dibutyltin dilaurate (DBTDL), isophorone diisocyanate (IPDI), polycaprolactone (PCL), castor oil-based silane (SCO) synthesized in S1 and dimethylglyoxime (DMG) to obtain a second mixture, reacting the second mixture at 75-80°C for 4-6h until the isocyanate group (-NCO) reaches the theoretical value, i.e., obtaining a castor oil-based polyurethane (DSCPU) having a large number of oxime urethane units and siloxane units; wherein the dibutyltin dilaurate (DBTDL) is a reaction catalyst.

[0035] In some embodiments, in the above S1 and S2, the mass ratio of castor oil (CO), mercaptopropyltrimethoxysilane (MPTEM), isophorone diisocyanate (IPDI), polycaprolactone (PCL) and dimethylglyoxime (DMG) is 1.56-6.22: 0.98-3.92: 8: 8-15: 1.97.

[0036] In certain preferred embodiments, in the above S1 and S2, the mass ratio of castor oil (CO), mercaptopropyltrimethoxysilane (MPTEM), isophorone diisocyanate (IPDI), polycaprolactone (PCL) and dimethylglyoxime (DMG) is 1.56:0.98:8:15:1.97.

[0037] In certain embodiments, during the reaction process of preparing castor oil-based polyurethane (DSCPU) in S2, 2-butanone is added to adjust the mass concentration of castor oil-based polyurethane (DSCPU) to 25-35%.

[0038] In certain embodiments, the amount of dibutyltin dilaurate (DBTDL) added is 0.1-0.2 mL.

[0039] In certain embodiments, in the above S3, the drying is carried out under vacuum conditions, wherein the drying temperature is 50-70° C., and the drying time is 10-24 hours.

[0040] Based on this, the present application provides a self-healing castor oil-based polyurethane, which is prepared by the aforementioned preparation method.

[0041] Based on this, an embodiment of the present application also provides an application of the aforementioned self-repairable castor oil-based polyurethane in the preparation of biomedical materials, electronic equipment, textiles, and coating products.

[0042] In the application of preparing biomedical materials, the self-repairable castor oil-based polyurethane prepared in the examples of the present application can be used to prepare artificial organs, tissue engineering scaffolds, drug delivery systems, wound dressings, etc.

[0043] In the application of preparing electronic devices, the self-repairable castor oil-based polyurethane prepared in the embodiments of the present application can be used to manufacture flexible circuit boards, sensors, etc. The self-repairing ability of these materials helps to improve the durability and reliability of the equipment.

[0044] In the application of preparing textiles, the self-repairable castor oil-based polyurethane prepared in the embodiments of the present application can be used to prepare high-performance textiles, such as elastic fibers, textile auxiliaries, waterproof and breathable textiles, shape memory textiles, etc.

[0045] In the application of preparing coating products, the self-repairable castor oil-based polyurethane prepared in the examples of the present application can be used to prepare self-repairing coatings. These products can self-repair after the coating is damaged to maintain its integrity and functionality.

[0046] The technical solution of the present application and the technical effects achieved are described in detail below through more specific embodiments.

[0047] Example 1

[0048] This embodiment provides a method for preparing a self-repairable castor oil-based polyurethane, and the specific steps are as follows:

[0049] (1) Synthesis of castor oil-based silane (SCO): First, 1.56 g of castor oil (CO), 0.98 g of mercaptopropyltrimethoxysilane (MPTMS) and 0.08 g of benzoin dimethyl ether (photoinitiator) were added to a sample bottle filled with argon to obtain a first mixture, and the mixture was irradiated under an ultraviolet lamp (365 nm, 1400 mW) to obtain castor oil-based silane (SCO) after overnight reaction;

[0050] (2) A castor oil-based polyurethane (DSCPU) solution was prepared by a one-pot method: 0.1 mL of dibutyltin dilaurate (DBTDL), 8 g of isophorone diisocyanate (IPDI), 15 g of polycaprolactone (PCL), castor oil-based silane (SCO) synthesized by S1, and 1.97 g of dimethylglyoxime (DMG) were mixed to obtain a second mixture, and the second mixture was reacted at 75° C. for 5 h until the isocyanate group (-NCO) reached a theoretical value, i.e., a castor oil-based polyurethane (DSCPU) having a large amount of oxime urethane units and siloxane units was obtained; during the reaction, 2-butanone was added as a solvent to adjust the mass concentration of the castor oil-based polyurethane (DSCPU) to 30%;

[0051] (3) The castor oil-based polyurethane (DSCPU) solution prepared in (2) was poured into a customized spindle-shaped polytetrafluoroethylene mold, and then placed in a vacuum environment at 60°C and dried for 12 h to remove the residual solvent, thereby obtaining a bubble-free castor oil-based polyurethane (DSCPU) film with a thickness of 0.4 mm, which was recorded as DSCPU5.

[0052] Example 2

[0053] This embodiment provides a method for preparing a self-repairable castor oil-based polyurethane, and the specific steps are as follows:

[0054] (1) Synthesis of castor oil-based silane (SCO): First, 3.11 g of castor oil (CO), 1.96 g of mercaptopropyltrimethoxysilane (MPTMS) and 0.17 g of benzoin dimethyl ether (photoinitiator) were added to a sample bottle filled with argon to obtain a first mixture, and the mixture was irradiated under an ultraviolet lamp (365 nm, 1400 mW) to obtain castor oil-based silane (SCO) after overnight reaction;

[0055] (2) A castor oil-based polyurethane (DSCPU) solution was prepared by a one-pot method: 0.1 mL of dibutyltin dilaurate (DBTDL), 8 g of isophorone diisocyanate (IPDI), 12.5 g of polycaprolactone (PCL), castor oil-based silane (SCO) synthesized by S1, and 1.97 g of dimethylglyoxime (DMG) were mixed to obtain a second mixture, and the second mixture was reacted at 80° C. for 4 h until the isocyanate group (-NCO) reached a theoretical value, i.e., a castor oil-based polyurethane (DSCPU) having a large amount of oxime urethane units and siloxane units was obtained; during the reaction, 2-butanone was added as a solvent to adjust the mass concentration of the castor oil-based polyurethane (DSCPU) to 30%;

[0056] (3) The castor oil-based polyurethane (DSCPU) solution prepared in (2) was poured into a customized spindle-shaped polytetrafluoroethylene mold, and then placed in a vacuum environment at 60°C and dried for 12 h to remove the residual solvent, thereby obtaining a bubble-free castor oil-based polyurethane (DSCPU) film with a thickness of 0.4 mm, which was recorded as DSCPU10.

[0057] Example 3

[0058] This embodiment provides a method for preparing a self-repairable castor oil-based polyurethane, and the specific steps are as follows:

[0059] (1) Synthesis of castor oil-based silane (SCO): First, 4.67 g of castor oil (CO), 2.95 g of mercaptopropyltrimethoxysilane (MPTMS) and 0.24 g of benzoin dimethyl ether (photoinitiator) were added to a sample bottle filled with argon to obtain a first mixture, and the mixture was irradiated under an ultraviolet lamp (365 nm, 1400 mW) to obtain castor oil-based silane (SCO) after overnight reaction;

[0060] (2) A castor oil-based polyurethane (DSCPU) solution was prepared by a one-pot method: 0.1 mL of dibutyltin dilaurate (DBTDL), 8 g of isophorone diisocyanate (IPDI), 10 g of polycaprolactone (PCL), castor oil-based silane (SCO) synthesized by S1, and 1.97 g of dimethylglyoxime (DMG) were mixed to obtain a second mixture, and the second mixture was reacted at 80° C. for 6 h until the isocyanate group (-NCO) reached a theoretical value, i.e., a castor oil-based polyurethane (DSCPU) having a large amount of oxime urethane units and siloxane units was obtained; during the reaction, 2-butanone was added as a solvent to adjust the mass concentration of the castor oil-based polyurethane (DSCPU) to 30%;

[0061] (3) The castor oil-based polyurethane (DSCPU) solution prepared in (2) was poured into a customized spindle-shaped polytetrafluoroethylene mold, and then placed in a vacuum environment at 60°C and dried for 12 h to remove the residual solvent, thereby obtaining a bubble-free castor oil-based polyurethane (DSCPU) film with a thickness of 0.4 mm, which was recorded as DSCPU15.

[0062] Example 4

[0063] This embodiment provides a method for preparing a self-repairable castor oil-based polyurethane, and the specific steps are as follows:

[0064] (1) Synthesis of castor oil-based silane (SCO): First, 6.22 g of castor oil (CO), 3.92 g of mercaptopropyltrimethoxysilane (MPTMS) and 0.31 g of benzoin dimethyl ether (photoinitiator) were added to a sample bottle filled with argon to obtain a first mixture, and the mixture was irradiated under an ultraviolet lamp (365 nm, 1400 mW) to obtain castor oil-based silane (SCO) after overnight reaction;

[0065] (2) A castor oil-based polyurethane (DSCPU) solution was prepared by a one-pot method: 0.1 mL of dibutyltin dilaurate (DBTDL), 8 g of isophorone diisocyanate (IPDI), 8 g of polycaprolactone (PCL), castor oil-based silane (SCO) synthesized by S1, and 1.97 g of dimethylglyoxime (DMG) were mixed to obtain a second mixture, and the second mixture was reacted at 75° C. for 5 h until the isocyanate group (-NCO) reached a theoretical value, i.e., a castor oil-based polyurethane (DSCPU) having a large amount of oxime urethane units and siloxane units was obtained; during the reaction, 2-butanone was added as a solvent to adjust the mass concentration of the castor oil-based polyurethane (DSCPU) to 30%;

[0066] (3) The castor oil-based polyurethane (DSCPU) solution prepared in (2) was poured into a customized spindle-shaped polytetrafluoroethylene mold, and then placed in a vacuum environment at 60°C and dried for 12 h to remove the residual solvent, thereby obtaining a bubble-free castor oil-based polyurethane (DSCPU) film with a thickness of 0.4 mm, which was recorded as DSCPU20.

[0067] Comparative Example 1

[0068] This comparative example provides a method for preparing a polyurethane material, and the specific steps are:

[0069] A polyurethane solution was prepared by a one-pot method: 0.1 mL of dibutyltin dilaurate (DBTDL), 8 g of isophorone diisocyanate (IPDI), 15 g of polycaprolactone (PCL) and 1.97 g of dimethylglyoxime (DMG) were mixed to obtain a mixture, and the mixture was reacted at 75° C. for 5 h to obtain a polyurethane solution; during the reaction, 2-butanone was added as a solvent to adjust the mass concentration of the polyurethane solution to 30%;

[0070] (3) The polyurethane solution prepared in (2) was poured into a customized spindle-shaped polytetrafluoroethylene mold, and then placed in a vacuum environment at 60°C and dried for 12 h to remove residual solvent, thereby obtaining a bubble-free polyurethane film with a thickness of 0.4 mm, which was recorded as DPU0.

[0071] The mechanical properties of DSCPU5, DSCPU10, DSCPU15, DSCPU20 prepared in Examples 1 to 4 and DPU0 prepared in Comparative Example 1 were tested. Since the polyurethane DPU0 film prepared in Comparative Example 1 did not introduce a siloxane structure, it was a soft material with very poor mechanical properties at room temperature. It could not maintain a spindle shape during demolding and was easily deformed by force. Therefore, the mechanical properties of DPU0 could not be measured. The mechanical property test results of the four films DSCPU5, DSCPU10, DSCPU15, and DSCPU20 are shown in Table 1 below.

[0072] Table 1

[0073]

[0074]

[0075] From the results in Table 1, it can be seen that the mechanical properties of the four film materials DSCPU5, DSCPU10, DSCPU15 and DSCPU20 can be significantly improved by adding SCO. With the increase of SCO content, the tensile strength of castor oil-based polyurethane (DSCPU) gradually increases, and the corresponding elongation at break gradually decreases.

[0076] The polyurethane films prepared in the examples and comparative examples were tested for their self-healing properties.

[0077] The examples of this application verify the self-healing properties of polyurethane films at room temperature. Figure 2 The figure shows the repair effect of DPU and DSCPU films at room temperature. The scratch changes on the film can more intuitively show the self-repair effect of the DSCPU series films. Figure 2 (a) to (e) are polarized microscope images of DSCPU films with different DPU and SCO contents before self-repair. After the above coatings were damaged, they were placed at room temperature for 7 days. Figure 2 (f) to (j) are the corresponding polarized microscope images after repair. DPU can be completely repaired and restored to a traceless state, but an applicable healing material needs to ensure both a high self-repair rate and certain mechanical properties. Although the control DPU has a high self-repair efficiency, DPU is a soft material that is easily deformed and has little application significance. The scratches of DSCPU are narrowed, showing an obvious room temperature self-repair effect, and it also has certain mechanical properties, so its actual application value is greater. Figure 2 It can be seen that DSCPU5 has the best self-repair effect.

[0078] The embodiment of the present application verifies the cross-section repair performance of the DSCPU film, and the specific method is as follows: Figure 3 As shown, the DSCPU5, DSCPU10, DSCPU15, and DSCPU20 films are cut in the middle for easy observation. Figure 3 As shown in (a), the fracture surface is painted red and blue with ink pens respectively, and the fracture surfaces on the front and back sides of the same sample are pressed for 1 minute. Figure 3 (b) and hang it on the wall with a dovetail clip. Figure 3 (c) shows the stretching process of DSCPU5. It can be seen from the figure that DSCPU5 can be bonded quickly. The repair effects of DSCPU10, DSCPU15, and DSCPU20 are inferior to DSCPU5, and the repair effect gradually decreases with the increase of SCO content.

[0079] The examples of the present application verify the repeatable repairability of the DSCPU film. Figure 4 The results of three fracture-repair cycles of the DSCPU5 film are shown. The results show that the fracture growth rate recovery rate of the DSCPU5 film is 80.3%, 70.9% and 54%, respectively, and the strain recovery rate is 59.2%, 52.1% and 35.2%, respectively.

[0080] The present invention tests the heating repair performance of the DSCPU5 film. The surface of a glass sheet covered with DSCPU5 and DSCPU10 coatings is scratched with a knife tip, and a hair dryer is used to blow hot air to remove the scratches on the surface. After about 30 minutes, Figure 5As shown, the scratches on the surface of the DSCPU5 coating have almost disappeared, indicating that the prepared DSCPU5 has the potential to meet the needs of convenient repair in specific areas.

[0081] The welding performance of the DSCPU film was tested in the examples of this application. Figure 6 The following is a test diagram of the welding performance of the DSCPU5 film. After the DSCPU5 film is cut in the middle, the colored parts are superimposed on each other. After pressing with fingers for 1 minute, the DSCPU5 film shows a certain degree of bonding performance. After being lifted vertically, it will not separate spontaneously under the action of gravity. Figure 6 As shown in (a), the DSCPU5 film was further placed at 110°C for heat-triggered welding for 8 hours, and the stretching distance exceeded more than twice its original length, as shown in Figure 6 As shown in (b), more importantly, after the DSCPU5 film welding material was pulled apart, the fracture point was located outside the welding point area, indicating that the DSCPU5 film has excellent welding performance. Compared with other self-healing polymers, DSCPU can show excellent weldability only by heat treatment without using any solvent.

[0082] In summary, the castor oil-based polyurethane (DSCPU) material prepared in the examples of the present application has both excellent self-healing and mechanical properties.

[0083] The present application is described in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the present application and its core ideas. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A method for preparing a self-repairable castor oil-based polyurethane, characterized in that: The specific steps are: S1. Synthetic castor oil-based silane; S2. Castor oil-based polyurethane was prepared by a one-pot method using polycaprolactone as a soft segment, isophorone diisocyanate as a hard segment, dimethylglyoxime as a chain extender, and castor oil-based silane obtained in S1 as a crosslinking agent; S3. Pour the castor oil-based polyurethane obtained in S2 into a spindle-shaped polytetrafluoroethylene mold, dry it, and remove the residual solvent to obtain the self-healing castor oil-based polyurethane.

2. The preparation method according to claim 1, characterized in that: In the above S1, the specific steps of synthesizing castor oil-based silane are: (1) adding castor oil, mercaptopropyltrimethoxysilane and an appropriate amount of photoinitiator into a sample bottle filled with inert gas to obtain a first mixture; (2) placing the sample bottle containing the first mixture under ultraviolet light for reaction, and obtaining castor oil-based silane after overnight reaction.

3. The preparation method according to claim 2, characterized in that: In step (1), the inert gas is argon, and the photoinitiator is dimethyl benzoate, which accounts for 1% to 4% by mass in the first mixture; in step (2), the wavelength of the ultraviolet light is 300 to 400 nm, and the light intensity is 1200 to 1500 mW.

4. The preparation method according to claim 1, characterized in that: In the above S2, the specific steps of preparing castor oil-based polyurethane are: Dibutyltin dilaurate, isophorone diisocyanate, polycaprolactone, castor oil-based silane synthesized by S1 and diacetyl oxime are mixed to obtain a second mixture, and the second mixture is reacted at 75-80°C for 4-6 hours until the isocyanate group reaches a theoretical value, that is, a castor oil-based polyurethane with a large number of oxime urethane units and siloxane units is obtained.

5. The preparation method according to claim 1, characterized in that: In the above S1 and S2, the mass ratio of castor oil, mercaptopropyltrimethoxysilane, isophorone diisocyanate, polycaprolactone and dimethylglyoxime is 1.56-6.22: 0.98-3.92: 8: 8-15: 1.

97.

6. The preparation method according to claim 1, characterized in that: In the above S1 and S2, the mass ratio of castor oil, mercaptopropyltrimethoxysilane, isophorone diisocyanate, polycaprolactone and dimethylglyoxime is 1.56:0.98:8:15:1.

97.

7. The preparation method according to claim 1, characterized in that: In certain embodiments, during the reaction process of preparing castor oil-based polyurethane in S2, 2-butanone is added to adjust the mass concentration of castor oil-based polyurethane to 25-35%, and the amount of dibutyltin dilaurate (DBTDL) added is 0.1-0.2 mL.

8. The preparation method according to claim 1, characterized in that: In the above S3, the drying is carried out under vacuum conditions, wherein the drying temperature is 50 to 70° C., and the drying time is 10 to 24 hours.

9. A self-repairable castor oil-based polyurethane, characterized in that: The method is prepared by any one of claims 1 to 8.

10. Use of the self-repairable castor oil-based polyurethane according to claim 9 in the preparation of biomedical materials, electronic equipment, textiles, and coating products.

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