Preparation method and application of degradable and fluorescent self-repairing polyurethane film

Abstract

The application discloses a preparation method and application of degradable and fluorescent self-repairing polyurethane film, and belongs to the technical field of high polymer materials. The carbon quantum dots are encapsulated in polylactic acid-based polyurethane through a Schiff base reaction, specifically, o-phenylenediamine and tryptophan are dissolved in a solvent, an acid solution and deionized water are added, a mixed solution is obtained through dissolution, the mixed solution is transferred into a Teflon-lined autoclave for reaction, and carbon quantum dots are obtained; (2) isocyanate, polyol and a dispersion solvent are used as raw materials, an organic tin catalyst is added, and a chain extender is added for reaction to obtain a polyurethane solution; (3) the carbon quantum dots are added into the polyurethane solution, the solution is poured onto a polytetrafluoroethylene base material after stirring, self-leveling and drying are performed, and the degradable and fluorescent self-repairing polyurethane film is obtained. The polyurethane material has good chemical stability, dispersibility and optical performance, simultaneously has self-repairing capability, and has good biodegradability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high polymer materials, and particularly relates to a preparation method and application of a degradable and fluorescent self-repairing polyurethane film. BACKGROUND

[0002] With the increasing demand for environmental protection and sustainable development, intelligent materials, especially polymer materials with degradable, fluorescent and self-repairing functions, have become a research hotspot. Carbon quantum dots have been widely used in many fields such as biosensing, optoelectronic devices and environmental monitoring due to their excellent optical properties, biocompatibility and environmental friendliness. However, carbon quantum dots face many challenges in practical applications, especially poor stability in solid matrix and easy aggregation, which leads to a decline in their optical properties. Therefore, how to improve the stability of carbon quantum dots while maintaining their excellent optical properties has become a major problem in current technology.

[0003] Polyurethane materials are widely used in the development of intelligent materials due to their excellent mechanical properties, wear resistance and thermal stability. However, traditional polyurethane is prone to aging and hardening during long-term use, and cannot self-repair, which limits its application in high-performance intelligent materials. To overcome this shortcoming, researchers have gradually explored the introduction of self-repairing mechanisms into polyurethane, enabling it to restore its original performance through certain repair mechanisms after damage. In addition, polyurethane materials based on polylactic acid have become a research focus in recent years due to their good biodegradability and environmental friendliness.

[0004] In the prior art, carbon quantum dots are introduced into polyurethane solution, such as patent CN118206785A, which introduces carbon quantum dots into polyurethane solution through physical blending technology, to prepare carbon quantum dot / waterborne polyurethane composite film. However, there are still the following problems: 1) the interfacial bonding force between carbon quantum dots and polyurethane matrix is weak; 2) carbon quantum dots are prone to aggregation in the polyurethane matrix; 3) the physical blending method cannot effectively improve the stability of carbon quantum dots, which may fall off or migrate during use; 4) the optical and mechanical properties of the material are significantly affected by the uneven distribution of carbon quantum dots. Therefore, current research still lacks an effective technology that can simultaneously improve the stability of carbon quantum dots, maintain their optical properties, and endow polyurethane with self-repairing and degradable functions. SUMMARY

[0005] [TECHNICAL PROBLEM]

[0006] The present application aims to provide a method for simultaneously improving the stability of carbon quantum dots, maintaining their optical properties, and endowing polyurethane with self-repairing function and degradability.

[0007] [TECHNICAL SCHEME]

[0008] To solve the above problems, the application provides a preparation method of degradable and fluorescent self-repairing polyurethane film, which realizes stable combination of carbon quantum dots and polyurethane solution by encapsulating the carbon quantum dots in polylactic acid-based polyurethane through Schiff base reaction, has better chemical stability, dispersion and optical performance, simultaneously endows the polyurethane material with self-repairing capability, and maintains good biodegradability.

[0009] The application provides a preparation method of degradable and fluorescent self-repairing polyurethane film, and specifically comprises the following steps:

[0010] (1) dissolving o-phenylenediamine and tryptophan in a solvent, adding an acid solution and deionized water, dissolving to obtain a mixed solution, transferring the mixed solution to a Teflon-lined autoclave for reaction, cooling, filtering, dialyzing and freeze-drying after the reaction is completed to obtain carbon quantum dots;

[0011] (2) taking isocyanate, polyol and a dispersion solvent as raw materials, adding an organic tin catalyst, reacting to obtain a polyurethane oligomer, and adding a chain extender to react to obtain a polyurethane solution;

[0012] (3) adding the carbon quantum dots to the polyurethane solution, casting the solution on a polytetrafluoroethylene substrate after stirring to perform self-leveling, and finally drying to obtain the degradable and fluorescent self-repairing polyurethane film.

[0013] In an embodiment of the application, in step (1), the solvent is one of anhydrous ethanol, acetone, N,N-dimethylformamide and dichloromethane, and the anhydrous ethanol is preferred.

[0014] In an embodiment of the application, in step (1), the acid solution is one of 12-18 mol / L hydrochloric acid aqueous solution, sulfuric acid aqueous solution, phosphoric acid aqueous solution and acetic acid aqueous solution, and the hydrochloric acid aqueous solution is preferred.

[0015] In an embodiment of the application, in step (1), the mass ratio of o-phenylenediamine to tryptophan is 0.14-0.56:0.528.

[0016] In an embodiment of the application, in step (1), the reaction temperature is 120-220 DEG C, and the reaction time is 4-10 h.

[0017] In an embodiment of the application, in step (1), the volume ratio of the solvent, the acid solution and the deionized water is 10-30:1-5:2-10.

[0018] In an embodiment of the application, in step (2), after the organic tin catalyst is added, the reaction temperature is 30-60 DEG C, and the reaction time is 1-5 h.

[0019] In an embodiment of the present application, in step (2), the isocyanate is one of 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,2-diphenylmethane diisocyanate, 4,4-diphenylmethane diisocyanate, isophorone diisocyanate, 1,3-butadiene-1,4-diisocyanate, 2,4,4-trimethyl 1,6-hexane diisocyanate, 1,6,11-undecane triisocyanate, preferably 1,6-hexane diisocyanate.

[0020] In an embodiment of the present application, in step (2), the polyol is a polylactic acid polyol.

[0021] In an embodiment of the present application, in step (2), the dispersion solvent is one of acetone, cyclohexanone, 1,4 dioxane, N,N-dimethylformamide, methyl tert-butyl ether, preferably N,N-dimethylformamide.

[0022] In an embodiment of the present application, in step (2), the organotin catalyst is one of diisobutyl tin dilaurate, stannous octoate, dibutyl tin bis (dodecylthio), dibutyl tin diacetate, preferably diisobutyl tin dilaurate.

[0023] In an embodiment of the present application, in step (2), the addition amount of isocyanate, polyol, and dispersion solvent is 0.01-0.05 mol:0.01 mol:5-30 mL, and the volume ratio of organotin catalyst and dispersion solvent is 0.05-0.25 mL:5-30 mL.

[0024] In an embodiment of the present application, in step (2), a chain extender is added, the temperature is adjusted to 60-100℃, and the reaction is carried out for 1-3 h, and a polyurethane solution is obtained after the reaction is completed.

[0025] In an embodiment of the present application, in step (2), the chain extender is 2-hydroxyethyl disulfide.

[0026] In an embodiment of the present application, in step (2), the molar ratio of chain extender and polyol is 0.2-0.8:1.

[0027] In an embodiment of the present application, in step (3), the addition amount of carbon quantum dots is 0.01-0.25% of the mass of the polyurethane solution.

[0028] The present application provides a degradable, fluorescent self-repairing polyurethane film prepared by the above-mentioned method.

[0029] The present application also provides the use of the above-mentioned degradable, fluorescent self-repairing polyurethane film on fabrics.

[0030] [Advantages]

[0031] (1) The present application significantly improves the stability of carbon quantum dots: The present application effectively encapsulates carbon quantum dots in a polyurethane matrix through Schiff base reaction, which can effectively inhibit the aggregation of carbon quantum dots in the solid matrix, significantly improve the stability and durability of carbon quantum dots in long-term use, and ensure that carbon quantum dots can still maintain good optical performance under different environmental conditions.

[0032] (2) The present application retains excellent fluorescence performance: Using polylactic acid-based polyurethane material, the present application can improve the stability of carbon quantum dots while maintaining their excellent fluorescence performance, ensuring the application advantages of the material in the fields of optoelectronics, sensing, etc., meeting the dual requirements of stability and brightness for high-performance fluorescent materials.

[0033] (3) The present application improves the self-repairing ability of the material: By introducing a self-repairing mechanism, the present application enables the polyurethane material to restore its original physical properties through internal chemical reactions after being damaged by external forces, greatly extending the service life of the material, and is particularly suitable for intelligent materials and environmentally friendly materials that require long-term use and durability.

[0034] (4) The present application has good biodegradability and environmental protection characteristics: Since polylactic acid is a degradable material, the prepared fluorescent self-repairing polyurethane not only has good biodegradability, but also can be naturally decomposed in the environment, meeting the demand for green and environmentally friendly materials in modern society, reducing resource waste and environmental pollution, and promoting the development of sustainable materials.

[0035] (5) The present application provides a simple, economical and environmentally friendly preparation process: The present application provides a simple, low-cost and environmentally friendly preparation method, which can efficiently synthesize the required material under mild conditions, and the raw materials used are non-toxic and harmless, meeting the requirements of green chemistry. The preparation process can be applied on a large scale in industrial production, and has significant economic benefits and social value.

[0036] (6) The application of the present application in wound detection: The polyurethane material of the present application has significant advantages in wound detection applications, mainly in the use of changes in the fluorescence brightness of the polyurethane material surface. When the polyurethane material surface appears a wound, due to the change of light refraction and reflection characteristics at the wound, the fluorescence brightness of the area is significantly improved. Through this phenomenon, the existence of the wound can be quickly and accurately detected, which has strong practicality, especially suitable for high-performance textile field, which can improve the quality control and use safety of the product. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is the transmission electron microscope image of the carbon dots of Example 1 of the present application;

[0038] Figure 2 is the infrared spectrum of the carbon dots and polyurethane of the embodiment 1 of the present application;

[0039] Figure 3 is the excitation and emission spectrum of the carbon dots of the embodiment 1 of the present application;

[0040] Figure 4 is the scanning electron microscope images of the polyurethane film of the embodiment 1 of the present application before (a) and after (b) degradation;

[0041] Figure 5 is the self-repairing process diagram of the polyurethane film of the embodiment 1 of the present application;

[0042] Figure 6 is the fluorescence photos of the X-shaped cracks on the surface of the film (a) and the fluorescence schematic diagram of the cracks on the surface of the film (b) of the embodiment 1 of the present application;

[0043] Figure 7 is the emission spectrum of the carbon dots solution of the embodiment 1 of the present application (red line) and the carbon dots solution after being placed for 15 days (black line);

[0044] Figure 8 is the emission spectrum of the polyurethane film of the embodiment 1 of the present application (purple line) and the polyurethane film after being placed for 15 days (blue line);

[0045] Figure 9 is the photos of the fluorescent polyurethane heat-pressed fabric of the embodiment 1 of the present application under visible light and ultraviolet light irradiation;

[0046] Figure 10 is the synthetic route diagram of the present application. DETAILED DESCRIPTION

[0047] The technical solutions described in the present application will be further described in detail through specific embodiments, but it is necessary to point out that the following embodiments are only used to describe the content of the present application and do not constitute a limitation to the protection scope of the present application.

[0048] The polylactic acid polyol used in the following embodiments is purchased from Wuhan Lalanbai Pharmaceutical Chemical Co., Ltd., the name is polylactic acid diol 2000, the molecular weight is 2000, and the batch number is 2024-712.

[0049] The test methods used in the present application are as follows:

[0050] (1) Transmission electron microscope analysis of carbon quantum dots

[0051] The carbon quantum dots are analyzed by using the American FEI Talos F200x transmission electron microscope, and the working voltage is set to 200kV.

[0052] (2) Infrared spectrum test of carbon quantum dots and polyurethane

[0053] Sample spectral data were collected at room temperature using a Thermo Scientific Nicolet is10 FTIR spectrometer equipped with a diamond ATR crystal. The spectral coverage was 4000 to 400 cm -1 with a resolution of 32 scans.

[0054] (3) Fluorescence spectrum test Fluorescence

[0055] The fluorescence spectrum of the carbon quantum dot sample was tested using a Hitachi F-7000 fluorescence spectrophotometer. The instrument was preheated and set to an excitation wavelength of 535 nm. The fluorescence emission spectrum scanning range was 555-750 nm, the slit width was 5 nm, and the scanning speed was 1200 nm / min.

[0056] (4) Tensile and self-repairing performance test of polyurethane

[0057] The self-repairing performance and mechanical properties of polyurethane were evaluated using an electronic universal testing machine. The tensile rate was set to 200 mm / min. According to the GB / T 1040.3-2006 standard, the PU sample was cut into dumbbell-shaped specimens with dimensions of 20 mm x 4 mm x 0.5 mm. The average value of each sample after 3 tests was taken as the final result. The self-healing efficiency was calculated using formula (1), where δ0 is the breaking strength of the original sample, δ1 is the breaking strength of the sample after repair, and the self-healing efficiency is represented by η.

[0058]

[0059] (5) Degradation performance test

[0060] The morphology of polyurethane before and after degradation was examined using a Regulus 8100 scanning electron microscope (Tokyo, Japan) at an acceleration voltage of 5.0 kV. Before SEM imaging, each sample surface was prepared by sputter coating with a fine layer of gold.

[0061] (6) Microscope test of polyurethane

[0062] A 10x20 optical microscope was selected to observe the scratch and repair of polyurethane before and after self-repairing. The self-repairing effect was evaluated by comparing the before and after photos.

[0063] (7) Fluorescent polyurethane wound detection effect test

[0064] A P(60)6 standard light source light box from Shanghai Kaloka Super Instrument Co., Ltd. was used to test the fluorescence effect of fluorescent polyurethane under standard light source and ultraviolet light source.

[0065] Example 1

[0066] A preparation method of a degradable, fluorescent self-repairing polyurethane film, comprising the following steps:

[0067] (1) 0.187g o-phenylenediamine and 0.528g tryptophan are dissolved in 20mL anhydrous ethanol, then, 1mL 12mol / L hydrochloric acid and 4mL water are added, the obtained mixture is ultrasonically treated to ensure complete dissolution, then is transferred to a polytetrafluoroethylene lined autoclave, the reaction is carried out at 180℃ for 6h, after completion, the autoclave is naturally cooled to room temperature, then the crude aqueous solution is filtered through a 0.22μm filter membrane to remove impurities and agglomerated particles, then the filtered solution is extensively dialyzed for 3 days using a 500Da dialysis bag to remove specific by-products and unreacted precursors, finally a black powder is obtained by freeze-drying, i.e. carbon quantum dots are obtained;

[0068] (2) 0.01mol polylactic acid polyol and 0.02mol 1,6-hexane diisocyanate are transferred to a three-necked round-bottom flask, 20mL N,N-dimethylformamide and 0.25mL catalyst diisobutyltin dilaurate are added, and the reaction is maintained at 40℃ for 1h, then 0.005mol 2-hydroxyethyl disulfide is added as a chain extender, the temperature is adjusted to 85℃ and the reaction is extended for another 2h, after the reaction, a polyurethane solution is obtained;

[0069] (3) 6g of the polyurethane solution is taken, 0.0006g carbon quantum dots are added, stirring is carried out at room temperature for 3h, the solution is degassed in a vacuum dryer at ambient temperature for 30min, then it is cast onto a polytetrafluoroethylene substrate for self-leveling, and then dried in a vacuum oven at 70℃ for 48h to eliminate residual solvents, thereby preparing a degradable, fluorescent self-repairing polyurethane film.

[0070] A degradable, fluorescent self-repairing polyurethane hot-pressed fabric: the previously prepared film is combined with a silk fabric in a hot press, the set conditions are a temperature of 90℃, a pressure of 8MPa, and a duration of 10min, and a fluorescent self-repairing polyurethane hot-pressed fabric is prepared.

[0071] The carbon dots show a characteristic lattice fringe of 0.208nm, which is consistent with the (100) plane lattice spacing of graphene. Figure 1 ).

[0072] The carbon dots show a prominent characteristic peak at 3396cm -1 , which corresponds to -NH2, indicating that there are amino groups on the surface of the carbon dots, which provide important reaction sites for subsequent Schiff base reactions, and the Fourier transform infrared spectrum of the polyurethane shows peaks at 2855cm -1 and 1744cm -1Characteristic peaks are observed at 1664 cm⁻¹, corresponding to the vibrations of -CH⁻ and -C=O, respectively, indicating the presence of these functional groups. These functional groups confirm the formation of the polyurethane structure and also provide sites for potential covalent bonds between polyurethane and carbon dots. In CDs@PU composites, a characteristic peak is observed at 1664 cm⁻¹. -1 A new peak was observed, attributed to the stretching vibration of -C=N-. The appearance of this peak clearly indicates that the Schiff base reaction occurred successfully, demonstrating that the carbon dots have been effectively covalently grafted onto the polyurethane matrix. Figure 2 ).

[0073] Fluorescence spectroscopy showed that the optimal emission wavelength of the carbon dots after excitation at 535 nm was determined to be 600 nm. Figure 3 Before degradation, the polyurethane film exhibited a smooth and uniform surface morphology. After 15 days of soil degradation, the surface morphology of all samples changed significantly, with the polyurethane showing obvious signs of surface erosion, including microcracks and pits, indicating that the material underwent biodegradation. Figure 4 ). Figure 5 The self-healing process of the polyurethane film is illustrated, showing the material's original state, damaged state, and repaired state. After the composite material was damaged, its integrity was restored through heating, and previously visible cracks almost disappeared after healing. Figure 6 As shown, an X-shaped crack forms on the surface of the polyurethane film. Under 365nm ultraviolet light irradiation, the fluorescence intensity in this region increases significantly. This fluorescence enhancement is directly attributed to optical phenomena occurring at the fracture site, specifically, as... Figure 6 As shown in (b), the roughness of the crack surface causes ultraviolet light to be refracted and scattered multiple times within the crack, and the geometry of the crack causes light to be refracted and reflected multiple times, thereby enhancing light capture and amplifying the fluorescence signal.

[0074] The fluorescence intensity of the original carbon dot solution decreased by more than 1000 after 15 days. Figure 7 The polyurethane film only decreased by about 300-400 after 15 days, which proves the stability of carbon quantum dots.

[0075] Photographs of polyurethane hot-pressed fabrics under visible and ultraviolet light irradiation, as shown below. Figure 9 As shown.

[0076] Example 2

[0077] A method for preparing a biodegradable, fluorescently self-healing polyurethane film includes the following steps:

[0078] 0.280 g of o-phenylenediamine and 0.528 g of tryptophan were dissolved in 25 mL of anhydrous ethanol, then 1.5 mL of 12 mol / L hydrochloric acid solution and 5 mL of deionized water were added, the mixture was ultrasonically treated at 40℃ for 20 min and then transferred to a polytetrafluoroethylene-lined autoclave, the reaction was carried out at 150℃ for 8 h, after completion, it was cooled to room temperature, the crude aqueous solution was filtered and dialyzed for 4 days to remove impurities, and finally freeze-dried to obtain a black powder, which was carbon quantum dots;

[0079] 0.01 mol of polylactic acid polyol and 0.015 mol of 1,6-hexane diisocyanate were transferred to a three-necked round-bottom flask, 25 mL of N,N-dimethylformamide and 0.15 mL of diisobutyltin dilaurate catalyst were added, and the reaction was carried out at 60℃ for 2 h, then 0.002 mol of 2-hydroxyethyl disulfide was added as a chain extender, the temperature was adjusted to 90℃, and the reaction was extended for 3 h to obtain a polyurethane solution;

[0080] 8 g of the polyurethane solution was taken, 0.0008 g of carbon quantum dots was added, stirred for 4 h, the solution was degassed in a vacuum dryer at ambient temperature for 30 min, then it was cast onto a polytetrafluoroethylene substrate for self-leveling, and then dried in a vacuum oven at 70℃ for 48 h to eliminate residual solvents, thereby preparing a degradable, fluorescent self-repairing polyurethane film.

[0081] A degradable, fluorescent self-repairing polyurethane hot-pressed fabric: the previously prepared film was combined with a silk fabric in a hot press, the conditions were set at a temperature of 90℃, a pressure of 8 MPa, and a duration of 10 min, and a fluorescent self-repairing polyurethane hot-pressed fabric was prepared.

[0082] Example 3

[0083] A method for preparing a degradable, fluorescent self-repairing polyurethane film, comprising the following steps:

[0084] 0.140 g of o-phenylenediamine and 0.528 g of tryptophan were dissolved in 30 mL of anhydrous ethanol, 2 mL of 12 mol / L hydrochloric acid and 3 mL of water were added, the mixture was ultrasonically treated at 30℃ for 10 min and then transferred to an autoclave, the reaction was carried out at 200℃ for 6 h, and after cooling, the carbon quantum dots were obtained by dialyzing for 3 days and drying to obtain a black powder, which was carbon quantum dots;

[0085] 0.01 mol of polylactic acid polyol and 0.025 mol of 1,6-hexane diisocyanate were added to 15 mL of N,N-dimethylformamide, and 0.05 mL of diisobutyltin dilaurate was added dropwise, and the reaction was carried out at 50℃ for 1 h, then 0.006 mol of chain extender 2-hydroxyethyl disulfide was added, the temperature was adjusted to 80℃, and the reaction was carried out for 2 h to obtain a polyurethane solution;

[0086] Take 4g polyurethane solution, add 0.0005g carbon quantum dots, stir for 2h, then degas the solution in a vacuum dryer at ambient temperature for 30min, then cast it on a polytetrafluoroethylene substrate for self-leveling, then dry it in a 70℃ vacuum oven for 48h to eliminate residual solvent, thus preparing a degradable, fluorescent self-repairing polyurethane film.

[0087] A degradable, fluorescent self-repairing polyurethane hot-pressed fabric: the pre-prepared film is combined with a silk fabric in a hot press, with the conditions set at a temperature of 90℃, a pressure of 8MPa, and a duration of 10min, to obtain a fluorescent self-repairing polyurethane hot-pressed fabric.

[0088] Example 4

[0089] A method for preparing a degradable, fluorescent self-repairing polyurethane film, comprising the following steps:

[0090] Dissolve 0.420g o-phenylenediamine and 0.528g tryptophan in 15mL anhydrous ethanol, add 3mL 12mol / L hydrochloric acid solution and 6mL water, ultrasonicate the mixture for 30min, then transfer it to an autoclave, react at 170℃ for 10h, cool, filter and dialyze for 5 days, dry to obtain carbon quantum dot powder, i.e. carbon quantum dots;

[0091] Transfer 0.01mol polylactic acid polyol and 0.03mol 1,6-hexane diisocyanate to a three-necked round-bottom flask, add 30mL N,N-dimethylformamide and 0.1mL stannous octoate catalyst, react at 55℃ for 3h, then add 0.008mol 2-hydroxyethyl disulfide chain extender, adjust the temperature to 95℃ and react for 1h, to obtain a polyurethane solution;

[0092] Take 10g polyurethane solution and 0.001g carbon quantum dots, stir for 5h, then degas the solution in a vacuum dryer at ambient temperature for 30min, then cast it on a polytetrafluoroethylene substrate for self-leveling, then dry it in a 70℃ vacuum oven for 48h to eliminate residual solvent, thus preparing a degradable, fluorescent self-repairing polyurethane film.

[0093] A degradable, fluorescent self-repairing polyurethane hot-pressed fabric: the pre-prepared film is combined with a silk fabric in a hot press, with the conditions set at a temperature of 90℃, a pressure of 8MPa, and a duration of 10min, to obtain a fluorescent self-repairing polyurethane hot-pressed fabric.

[0094] Example 5

[0095] A method for preparing a degradable, fluorescent self-repairing polyurethane film, comprising the following steps:

[0096] Dissolve 0.187 g of o-phenylenediamine and 0.528 g of tryptophan in 25 mL of dichloromethane, add 2 mL of 18 mol / L sulfuric acid solution and 6 mL of water, ultrasonic the mixture for 20 min, then transfer it to an autoclave, and react at 190℃ for 8 h. After cooling, dialysis for 3 days and drying, a black powder is obtained, which is carbon quantum dots.

[0097] Take 0.01 mol of polylactic acid polyol and 0.04 mol of isophorone diisocyanate, add 20 mL of N,N-dimethylformamide, and drop 0.25 mL of catalyst diisobutyltin dilaurate. React at 45℃ for 2 h, then add 0.004 mol of chain extender 2-hydroxyethyl disulfide, adjust the temperature to 80℃ and react for 1.5 h to obtain a polyurethane solution.

[0098] Take 5 g of polyurethane solution and 0.0006 g of carbon quantum dots, mix for 3 h, then degas the solution in a vacuum dryer at ambient temperature for 30 min, then cast it on a polytetrafluoroethylene substrate for self-leveling, and then dry it in a vacuum oven at 70℃ for 48 h to eliminate residual solvent, thereby preparing a degradable, fluorescent self-repairing polyurethane film.

[0099] A degradable, fluorescent self-repairing polyurethane hot-pressed fabric: the previously prepared film is combined with a silk fabric in a hot press, with the conditions set at a temperature of 90℃, a pressure of 8 MPa, and a duration of 10 min, to obtain a fluorescent self-repairing polyurethane hot-pressed fabric.

[0100] Comparative Example 1

[0101] Take 0.01 mol of 2,6-toluene diisocyanate, 0.02 mol of polytetrahydrofuran diol, 10 mL of N,N-dimethylformamide, and drop 0.25 mL of catalyst diisobutyltin dilaurate into a 500 mL four-necked flask. React at 60℃ for 2 h, then add 0.004 mol of chain extender 2,2-dimethylol propionic acid, adjust the temperature to 90℃ and react for 1.5 h to obtain a polyurethane solution. Degas the solution in a vacuum dryer at ambient temperature for 30 min, then cast it on a polytetrafluoroethylene substrate for self-leveling, and then dry it in a vacuum oven at 70℃ for 48 h to eliminate residual solvent, thereby obtaining a control polyurethane.

[0102] Comparative Example 2

[0103] Take 0.1 g of lignin and 0.1 g of o-phenylenediamine, dissolve in 20 mL of ethanol, ultrasonic dispersion for 10 min, transfer the solution to a reaction kettle lined with tetrafluoroethylene, seal well. In the oven at 200 DEG C for 5h, cool to room temperature to obtain the crude product. By centrifugation, dialysis, freeze-drying of the crude product, carbon quantum dots are obtained; centrifugation is centrifuged at 10000r / min for 10 min; the dialysis is carried out by using a dialysis bag with a molecular weight cut-off of 1000 Da.

[0104] To 10 g of waterborne polyurethane (solid content 30%) add 5 mL of carbon quantum dots ethanol solution with a concentration of 1 mg / mL, disperse with ultrasonic wave for 30 min. Stand for 24 h, heat at 130 DEG C for 2 h. Successfully prepared a waterborne polyurethane / carbon quantum dots composite film with a mass fraction of 0.167wt%.

[0105] Table 1 Performance test of polyurethane film prepared in examples 1-5 and comparative examples 1-2

[0106]

[0107] The degradable, fluorescent self-repairing polyurethane prepared by the application has different tensile properties and self-repairing abilities by optimizing various performance parameters. Examples 1 and 2 perform excellently in tensile elongation and self-repairing efficiency, especially example 2 is outstanding in tensile strength and self-repairing ability, which is suitable for high-strength applications with certain repair needs. Examples 3 and 5 are slightly inferior in performance, but still have good tensile properties and self-repairing ability, which is suitable for medium-strength applications. Example 4 is relatively inferior in various performances, which is suitable for low-strength applications. In general, the polyurethane material prepared by the application has good adjustability and can meet the performance needs of different application occasions.

[0108] The above provided examples are not intended to limit the scope covered by the application, and the described steps are not intended to limit the execution order. Those skilled in the art can make obvious improvements to the application in combination with existing common knowledge, which also falls within the protection scope defined by the claims of the application.

Claims

1. A method for preparing a degradable, fluorescent self-healing polyurethane film, characterized in that, It comprises the following steps: (1) dissolving o-phenylenediamine and tryptophan in a solvent, adding an acid solution and deionized water, dissolving to obtain a mixed solution, transferring the mixed solution to a Teflon-lined autoclave for reaction, cooling, filtering, dialysis and freeze-drying after the reaction is completed to obtain carbon quantum dots; (2) taking isocyanate, polyol and dispersion solvent as raw materials, adding organic tin catalyst to obtain polyurethane oligomer, and adding chain extender to obtain polyurethane solution; The isocyanate is one of 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,2-diphenylmethane diisocyanate, 4,4-diphenylmethane diisocyanate, isophorone diisocyanate, 1,3-butadiene-1,4-diisocyanate, 2,4,4-trimethyl 1,6-hexane diisocyanate and 1,6,11-undecane triisocyanate; the polyol is polylactic acid polyol; the dispersion solvent is one of acetone, cyclohexanone, 1,4 dioxane, N,N-dimethylformamide and methyl tert-butyl ether; and the organic tin catalyst is one of diisobutyl tin dilaurate, stannous octoate, dibutyl tin bis (dodecyl sulfide) and dibutyl tin diacetate. The reaction temperature is 30-60℃, and the reaction time is 1-5h; the chain extender is added, the temperature is adjusted to 60-100℃, and the reaction is carried out for 1-3h to obtain the polyurethane solution; the chain extender is 2-hydroxyethyl disulfide; and the molar ratio of the chain extender to the polyol is 0.2-0.8:

1. (3) adding carbon quantum dots to the polyurethane solution, pouring the solution onto a polytetrafluoroethylene substrate after stirring to perform self-leveling, and finally drying to obtain a degradable and fluorescent self-repairing polyurethane film; the mass fraction of the carbon quantum dots in the polyurethane solution is 0.01-0.25%.

2. The method according to claim 1, wherein, In step (1), the solvent is one of anhydrous ethanol, acetone, N,N-dimethylformamide and dichloromethane; and the acid solution is one of 12-18mol / L hydrochloric acid aqueous solution, sulfuric acid aqueous solution, phosphoric acid aqueous solution and acetic acid aqueous solution.

3. The method according to claim 1, wherein, In step (1), the mass ratio of o-phenylenediamine to tryptophan is 0.14-0.56:0.528; and the volume ratio of the solvent, the acid solution and deionized water is 10-30:1-5:2-10.

4. The method according to claim 1, wherein, In step (1), the reaction temperature is 120-220℃, and the reaction time is 4-10h.

5. The method for preparing a biodegradable, fluorescently self-healing polyurethane film according to claim 1, characterized in that, In step (2), the addition amount of isocyanate, polyol and dispersion solvent is 0.01-0.05mol:0.01mol:5-30mL; and the volume ratio of the organic tin catalyst to the dispersion solvent is 0.05-0.25mL:5-30mL.

6. The degradable and fluorescent self-repairing polyurethane film prepared by the method of any one of claims 1-5.

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