Amino silicon dioxide confinement carbon dot-based waterborne polyurethane with ultra-long phosphorescence service life and preparation method thereof

Abstract

The invention relates to the technical field of luminescent materials, in particular to amino silicon dioxide confined carbon dot-based waterborne polyurethane with an ultra-long phosphorescence service life and a preparation method of the amino silicon dioxide confined carbon dot-based waterborne polyurethane with the ultra-long phosphorescence service life. Then limiting the carbon dots in a silicon dioxide encapsulation layer according to a Stber method to prepare water-soluble green phosphorescent carbon dots, then modifying the water-soluble green phosphorescent carbon dots through (3-aminopropyl)-trimethoxysilane to obtain a phosphorescent carbon dot-amino silicon dioxide composite material, and finally, taking the phosphorescent carbon dot-amino silicon dioxide composite material as a chain extender to be connected to a polyurethane main chain to prepare the polyurethane composite material. The synthetic process of the method disclosed by the invention has the characteristics of safety, reliability, convenience in operation, easiness in recovery and the like, and the product has the characteristics of ultra-long phosphorescence service life, good product stability, good water resistance, anti-counterfeiting identification and the like.

Description

Technical Field

[0001] This invention relates to the field of luminescent materials technology, specifically to an ultra-long phosphorescence lifetime waterborne polyurethane based on amino silica-confined carbon dots and its preparation method. Background Technology

[0002] Luminescent polymers are a class of polymeric compounds that emit visible light in response to external stimuli such as light, electricity, and heat. While this luminescence mechanism performs well in many applications, it also has limitations, primarily short luminescence lifetime, insufficient stability, and limited luminescence efficiency. Due to these limitations, fluorescent polymers may not meet the requirements of some applications (such as security indicators and anti-counterfeiting encryption). Therefore, researchers are exploring other luminescence mechanisms, such as phosphorescence, chemiluminescence, and electroluminescence, to overcome these limitations and develop luminescent polymers with superior performance.

[0003] With increasing public awareness of environmental protection and sustainable development, waterborne polyurethane, using water as a dispersion medium, offers advantages such as low volatile organic compound emissions, non-toxicity, and non-flammability, gradually becoming an ideal alternative to traditional solvent-based polyurethane. Waterborne polyurethane not only retains the excellent wear resistance, flexibility, and chemical corrosion resistance of polyurethane materials but also boasts significant advantages in environmental performance, thus demonstrating broad application prospects in various fields such as coatings, adhesives, leather, textiles, and biomedicine.

[0004] In recent years, carbon quantum dots (CQDs), as an emerging carbon nanomaterial, have attracted widespread attention due to their advantages such as low synthesis cost, good optical stability, low toxicity, and ease of surface functionalization. The composite of carbon quantum dots with polymer materials has become a research hotspot. For example, CN108822527A discloses the use of amino / hydroxyl carbon dots synthesized by a hydrothermal method as chain extenders, which are then chemically bonded to waterborne polyurethane through in-situ polymerization, improving the material's mechanical properties and transparency while imparting fluorescent properties. CN118165637A describes the construction of porous SiO2@CDs composite microspheres combined with waterborne polyurethane, utilizing the confinement effect of silica to reduce carbon dot aggregation, significantly improving the coating's adhesion, mechanical strength, and fluorescent properties, making it suitable for fluorescent anti-counterfeiting.

[0005] Although the above technologies have made progress in the functional modification of waterborne polyurethane, the following limitations still exist: CN108822527A mainly focuses on carbon quantum dots as chain extenders to enhance mechanical and fluorescent properties, but it does not solve the problem of long-term dispersion stability of carbon dots in polyurethane and the realization of phosphorescence performance; CN118165637A alleviates the agglomeration problem by loading carbon dots with porous silica, but the carbon dots and polyurethane are mainly composited by physical blending, and the interfacial bonding force is limited, which may lead to performance degradation during long-term use; phosphorescent polyurethanes prepared by existing doping methods (such as CN119060528A) have problems such as insufficient long-term stability, limited luminous efficiency, and high risk of fluorescence quenching.

[0006] In view of the above-mentioned defects, the inventors of this invention have finally obtained this invention after a long period of research and practice. Summary of the Invention

[0007] The purpose of this invention is to solve the problems of insufficient long-term stability, limited luminescence efficiency, and risk of fluorescence quenching in phosphorescent polyurethane prepared by doping method, and to provide an ultra-long phosphorescence lifetime waterborne polyurethane based on amino silica confined carbon dots and its preparation method.

[0008] To achieve the above objectives, this invention discloses a method for preparing an ultra-long phosphorescence lifetime waterborne polyurethane based on amino silica-confined carbon dots, comprising the following steps:

[0009] S1, carbon dot powder was synthesized in pure water solvent using phosphoric acid and ethylenediamine as raw materials;

[0010] S2, according to the Stöber method, carbon dot powder is confined in a silicon dioxide encapsulation layer to obtain water-soluble phosphorescent carbon dots;

[0011] S3, the water-soluble phosphorescent carbon dots obtained in step S2 are modified with (3-aminopropyl)-trimethoxysilane to obtain a carbon dot@aminosilica composite material.

[0012] S4, under a nitrogen atmosphere, the dehydrated isocyanate and polymer polyol are reacted at 50-60℃ for 20-30 min, then the temperature is raised to 80-90℃ and the reaction continues for 2-3 h. Diol chain extender and catalyst are added, and the reaction is carried out at 70-80℃ for 2-3 h. Then hydrophilic chain extender is added and the reaction is carried out at 60-80℃ for 2-3 h to generate polyurethane prepolymer.

[0013] S5. After the reaction system in step S4 is cooled to 40-60℃, add the carbon dot@amino silica composite material that is ultrasonically dispersed in an organic solvent and react for 3-4 hours. Cool down to 30-40℃, add a neutralizing agent, react for 30-40 minutes, add ultrapure water and disperse at high speed for 20-30 minutes. Remove the solvent in a rotary evaporator at 50-60℃ to obtain an ultra-long phosphorescence lifetime waterborne polyurethane emulsion based on carbon dot@amino silica.

[0014] In step S1, the specific process is as follows: Ethylenediamine is dissolved in deionized water, and then phosphoric acid is slowly added to the ethylenediamine aqueous solution and stirred for 10 min. The resulting transparent solution is heated in a 750 W microwave oven for 130°C. After the sample cools to room temperature, deionized water is added to form a pale yellow solution. The aqueous solution is centrifuged for 10 min to remove the precipitate. The supernatant is filtered through a 0.22 μm membrane and neutralized with sodium carbonate. The supernatant is collected and dialyzed for 24 h. During dialyzing, the MWCO is 500 Da. Finally, the carbon dot powder is obtained by freeze drying.

[0015] In step S2, the specific process is as follows: dissolve carbon dot powder in deionized water, add tetraethoxysilane and disperse it in deionized water to form an aqueous solution, adjust the pH to 9-10 with ammonia, and stir at room temperature for 16 hours to form a colorless and transparent solution, which is the water-soluble phosphorescent carbon dot.

[0016] In step S3, the specific process is as follows: (3-aminopropyl)-trimethoxysilane is dissolved in deionized water and sonicated for 10 min. The aqueous solution coated with silica is added, and the pH is adjusted to 9-10 with ammonia. The solution is stirred at room temperature for 8 h to obtain an aqueous solution with flocculent precipitate. The solution is neutralized with glacial acetic acid and finally cooled and dried to obtain a white powder, which is the carbon dot@aminosilica composite material.

[0017] In step S4, the isocyanate is one or more of toluene diisocyanate, 1,6-hexane diisocyanate, 4,4-diphenylmethane diisocyanate, isophorone diisocyanate, 1,5-naphthalene diisocyanate, polymethylene polyphenyl polyisocyanate, methylcyclohexyl diisocyanate, and dicyclohexylmethane diisocyanate, accounting for 5-30% of the total weight of the polyurethane prepolymer.

[0018] In step S4, the polymer polyol is one or more of the following: polybutadiene glycol, polypropylene oxide glycol, tetrahydrofuran-propylene oxide copolymer glycol, polybutadiene-acrylonitrile alcohol, polyethylene adipate glycol, polyhexanediol carbonate, polyethylene adipate-propylene glycol, polydiethylene adipate glycol, polytetrahydrofuran glycol, polyricinoleate adipate, polycaprolactone glycol, and polybutanediol adipate, accounting for 20-50% of the total weight of the polyurethane prepolymer.

[0019] In step S4, the specific dehydration process is as follows: the isocyanate and polymer polyol are dehydrated at 110-120℃ and under a vacuum of ≤0.1MPa for 4 hours.

[0020] In step S4, the diol chain extender is one or more of ethylene glycol (EG), diethylene glycol (DEG), dipropylene glycol (DPG), 1,2-propanediol (1,2-PG), 1,4-butanediol (BDO), neopentyl glycol (NPG), and 1,6-hexanediol (HD), accounting for 0-7% of the total weight; the catalyst is one or more of organotin and tertiary amine catalysts, accounting for 0.01-0.03% of the total weight of the polyurethane prepolymer; and the hydrophilic chain extender is 2,2-dihydroxybutyric acid or 2,2-dihydroxypropionic acid, accounting for 5-8% of the total weight of the polyurethane prepolymer.

[0021] In step S5, the organic solvent is one or more of acetone, butanone, cyclohexanone, tetrahydrofuran, dimethyl sulfoxide, N,N-dimethylformamide, toluene, dioxane, and ethyl acetate, accounting for 20-40% of the total weight of the polyurethane prepolymer; the neutralizing agent is one or more of triethylamine, sodium hydroxide, ammonia, sodium bicarbonate, and potassium hydroxide, accounting for 5-8% of the total weight of the polyurethane prepolymer.

[0022] The present invention also discloses an ultra-long phosphorescence lifetime waterborne polyurethane based on amino silica confined carbon dots prepared by the above preparation method.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. The waterborne polyurethane with ultralong phosphorescence lifetime based on amino silica confined carbon dots prepared by the method of the present invention can achieve a visible green afterglow of 9s after the excitation source is turned off.

[0025] 2. The waterborne polyurethane with ultralong phosphorescence lifetime based on amino silica confined carbon dots prepared by the method of the present invention has good biocompatibility and environmental performance.

[0026] 3. The ultra-long phosphorescence lifetime waterborne polyurethane based on amino silica confined carbon dots prepared by the method of the present invention has enhanced mechanical strength and chemical stability of polyurethane because the polyurethane prepolymer is chemically incorporated into the polyurethane molecular chain. Attached Figure Description

[0027] Figure 1 The synthesis process of carbon dot@amino silica composite material;

[0028] Figure 2 This describes the synthesis process of an ultra-long phosphorescence lifetime waterborne polyurethane based on amino silica-confined carbon dots.

[0029] Figure 3 The fluorescence emission spectrum (a) and fluorescence CIE coordinate diagram (b) of the waterborne polyurethane with ultralong phosphorescence lifetime based on amino silica confined carbon dots obtained in Examples 1-5 of this invention under 368 nm ultraviolet light irradiation.

[0030] Figure 4 The following are the phosphorescence emission spectra of the waterborne polyurethane with ultra-long phosphorescence lifetime based on amino silica confined carbon dots obtained in Examples 1-5 of this invention under 368 nm ultraviolet light irradiation and after removing ultraviolet light of different wavelengths: (a) phosphorescence emission spectrum; (b) phosphorescence CIE coordinate diagram.

[0031] Figure 5 The ultra-long phosphorescence lifetime waterborne polyurethane emulsions based on amino silica-confined carbon dots obtained by adding different amounts of carbon dot@amino silica composite materials in Examples 2-5 of this invention, wherein (a) is NSi-CNDs-WPU 0.1 (a) Fluorescence and phosphorescence effects; (b) NSi-CNDs-WPU 0.5 Fluorescence and phosphorescence effects; (c) shows NSi-CNDs-WPU 1.0 Fluorescence and phosphorescence effects; (d) shows NSi-CNDs-WPU. 3.0 Fluorescence and phosphorescence effects.

[0032] Figure 6 The ultra-long phosphorescence lifetime waterborne polyurethane film based on amino silica confined carbon dots obtained in Example 6 of the present invention includes: (a) the imaging of the pattern in the ultraviolet light-on (λex=368nm) and off states; (b) the information encryption image of the number "8888" in the ultraviolet light-on (λex=368nm) and off states; and (c) the anti-counterfeiting image of the QR code film in the ultraviolet light-on (λex=368nm) and off states. Detailed Implementation

[0033] The above-mentioned and other technical features and advantages of the present invention will be described in more detail below with reference to the accompanying drawings.

[0034] Example 1

[0035] Ethylenediamine was dissolved in deionized water, and then phosphoric acid was slowly added to the ethylenediamine aqueous solution and stirred for 10 min. The resulting clear solution was heated in a 750 W microwave oven for 130 s. After the sample cooled to room temperature, deionized water was added to the sample to form a pale yellow solution. The aqueous solution was centrifuged for 10 min to remove precipitates. The supernatant was filtered through a 0.22 μm membrane and neutralized with sodium carbonate. The supernatant was collected and dialyzed for 24 h (MWCO: 500 Da). Finally, it was freeze-dried to obtain a pale yellow solid carbon dot powder.

[0036] Carbon dot powder is dissolved in a certain amount of deionized water, and tetraethoxysilane (TEOS) is added and dispersed in the deionized water to form an aqueous solution. The pH is adjusted to 9-10 with ammonia water, and after stirring at room temperature for 16 hours, a colorless and transparent solution is formed, which is the water-soluble phosphorescent carbon dot.

[0037] (3-aminopropyl)-trimethoxysilane was dissolved in deionized water and sonicated for 10 min. The aqueous solution coated with silica was added, and the pH was adjusted to 9-10 with ammonia. The mixture was stirred at room temperature for 8 h to obtain an aqueous solution with flocculent precipitate. The solution was neutralized with glacial acetic acid and finally cooled and dried to obtain a white powder, which is the carbon dot@aminosilica composite material.

[0038] Polytetrahydrofuran diol and isophorone diisocyanate (IPDI) were dehydrated at 90°C and under a vacuum of ≤0.1MPa for 8 hours.

[0039] Under nitrogen atmosphere protection, 14g of dried polytetrahydrofuran diol and 12g of isophorone diisocyanate (IPDI) were added to a four-necked flask equipped with a thermometer, a PTFE stirring paddle, and a reflux condenser. The mixture was reacted at 50°C for 20 min, and then the temperature was raised to 90°C to continue the reaction for 2 h.

[0040] Add 1.2g of 1,4-butanediol, 0.01g of dibutyltin dilaurate and 50g of acetone, and react at 80℃ for 2h. Then add 2.0g of 2,2-dimethylolbutyric acid and react at 80℃ for 2h to generate a polyurethane prepolymer.

[0041] Cool to 30℃, add 1.5g of triethylamine, and react for 30 minutes;

[0042] Add 140 mL of ultrapure water and disperse at high speed for 30 min. Remove acetone in a rotary evaporator at 50 °C to obtain the waterborne polyurethane emulsion (WPU). The waterborne polyurethane prepared in this example serves as a blank control group and exhibits no fluorescence.

[0043] Example 2

[0044] Ethylenediamine was dissolved in deionized water, and then phosphoric acid was slowly added to the ethylenediamine aqueous solution and stirred for 10 min. The resulting clear solution was heated in a 750 W microwave oven for 130 s. After the sample cooled to room temperature, deionized water was added to the sample to form a pale yellow solution. The aqueous solution was centrifuged for 10 min to remove precipitates. The supernatant was filtered through a 0.22 μm membrane and neutralized with sodium carbonate. The supernatant was collected and dialyzed for 24 h (MWCO: 500 Da). Finally, it was freeze-dried to obtain a pale yellow solid carbon dot powder.

[0045] Carbon dot powder is dissolved in a certain amount of deionized water, and tetraethoxysilane (TEOS) is added and dispersed in the deionized water to form an aqueous solution. The pH is adjusted to 9-10 with ammonia water, and after stirring at room temperature for 16 hours, a colorless and transparent solution is formed, which is the water-soluble phosphorescent carbon dot.

[0046] (3-aminopropyl)-trimethoxysilane was dissolved in deionized water and sonicated for 10 min. The aqueous solution coated with silica was added, and the pH was adjusted to 9-10 with ammonia. The mixture was stirred at room temperature for 8 h to obtain an aqueous solution with flocculent precipitate. The solution was neutralized with glacial acetic acid and finally cooled and dried to obtain a white powder, which is the carbon dot@aminosilica composite material.

[0047] Polytetrahydrofuran diol and isophorone diisocyanate (IPDI) were dehydrated at 110°C and under a vacuum of ≤0.1MPa for 4 hours.

[0048] Under nitrogen atmosphere protection, 14g of dried polytetrahydrofuran diol and 12g of isophorone diisocyanate (IPDI) were added to a four-necked flask equipped with a thermometer, a PTFE stirring paddle, and a reflux condenser. The mixture was reacted at 50°C for 20 min, and then the temperature was raised to 90°C to continue the reaction for 2 h.

[0049] Add 1.2g of 1,4-butanediol, 0.01g of dibutyltin dilaurate and 50g of acetone, react at 80℃ for 2min, then add 2.0g of 2,2-dimethylolbutyric acid and react at 80℃ for 2h to generate a polyurethane prepolymer;

[0050] After cooling to 60°C, 0.0307g of carbon dot@amino silica composite powder, which was ultrasonically dispersed in 10g of acetone, was added and reacted for 4h.

[0051] Cool to 30℃, add 1.5g of triethylamine, and react for 30 minutes;

[0052] Add 140 mL of ultrapure water and disperse at high speed for 30 min. Remove acetone in a rotary evaporator at 50 °C to obtain the ultra-long phosphorescence lifetime waterborne polyurethane emulsion (NSi-CNDs-WPU) based on carbon dots@amino silica. 0.1 The fluorescent waterborne polyurethane prepared in this embodiment emits blue fluorescence under 365nm ultraviolet light irradiation and emits green phosphorescence after the ultraviolet light is turned off.

[0053] Example 3

[0054] Ethylenediamine was dissolved in deionized water, and then phosphoric acid was slowly added to the ethylenediamine aqueous solution and stirred for 10 min. The resulting clear solution was heated in a 750 W microwave oven for 130 s. After the sample cooled to room temperature, deionized water was added to the sample to form a pale yellow solution. The aqueous solution was centrifuged for 10 min to remove precipitates. The supernatant was filtered through a 0.22 μm membrane and neutralized with sodium carbonate. The supernatant was collected and dialyzed for 24 h (MWCO: 500 Da). Finally, it was freeze-dried to obtain a pale yellow solid carbon dot powder.

[0055] Carbon dot powder is dissolved in a certain amount of deionized water, and tetraethoxysilane (TEOS) is added and dispersed in the deionized water to form an aqueous solution. The pH is adjusted to 9-10 with ammonia water, and after stirring at room temperature for 16 hours, a colorless and transparent solution is formed, which is the water-soluble phosphorescent carbon dot.

[0056] (3-aminopropyl)-trimethoxysilane was dissolved in deionized water and sonicated for 10 min. The aqueous solution coated with silica was added, and the pH was adjusted to 9-10 with ammonia. The mixture was stirred at room temperature for 8 h to obtain an aqueous solution with flocculent precipitate. The solution was neutralized with glacial acetic acid and finally cooled and dried to obtain a white powder, which is the carbon dot@aminosilica composite material.

[0057] Polytetrahydrofuran diol and isophorone diisocyanate (IPDI) were dehydrated at 110°C and under a vacuum of ≤0.1MPa for 4 hours.

[0058] Under nitrogen atmosphere protection, 14g of dried polytetrahydrofuran diol and 12g of isophorone diisocyanate (IPDI) were added to a four-necked flask equipped with a thermometer, a PTFE stirring paddle, and a reflux condenser. The mixture was reacted at 50°C for 20 min, and then the temperature was raised to 90°C to continue the reaction for 2 h.

[0059] Add 1.2g of 1,4-butanediol, 0.01g of dibutyltin dilaurate and 50g of acetone, and react at 80℃ for 2h. Then add 2.0g of 2,2-dimethylolbutyric acid and react at 80℃ for 2h to generate a polyurethane prepolymer.

[0060] After cooling to 60°C, 1.1535g of carbon dot@amino silica composite powder was added to 10g of acetone and ultrasonically dispersed for 4h.

[0061] Cool to 30℃, add 1.5g of triethylamine, and react for 30 minutes;

[0062] Add 140 mL of ultrapure water and disperse at high speed for 30 min. Remove acetone in a rotary evaporator at 50 °C to obtain an ultra-long phosphorescence lifetime waterborne polyurethane emulsion (NSi-CNDs-WPU) based on amino silica-confined carbon dots. 0.5The fluorescent waterborne polyurethane prepared in this embodiment emits blue fluorescence under 365nm ultraviolet light irradiation and emits green phosphorescence after the ultraviolet light is turned off.

[0063] Example 4

[0064] Ethylenediamine was dissolved in deionized water, and then phosphoric acid was slowly added to the ethylenediamine aqueous solution and stirred for 10 min. The resulting clear solution was heated in a 750 W microwave oven for 130 s. After the sample cooled to room temperature, deionized water was added to the sample to form a pale yellow solution. The aqueous solution was centrifuged for 10 min to remove precipitates. The supernatant was filtered through a 0.22 μm membrane and neutralized with sodium carbonate. The supernatant was collected and dialyzed for 24 h (MWCO: 500 Da). Finally, it was freeze-dried to obtain a pale yellow solid carbon dot powder.

[0065] Carbon dot powder is dissolved in a certain amount of deionized water, and tetraethoxysilane (TEOS) is added and dispersed in the deionized water to form an aqueous solution. The pH is adjusted to 9-10 with ammonia water, and after stirring at room temperature for 16 hours, a colorless and transparent solution is formed, which is the water-soluble phosphorescent carbon dot.

[0066] (3-aminopropyl)-trimethoxysilane was dissolved in deionized water and sonicated for 10 min. The aqueous solution coated with silica was added, and the pH was adjusted to 9-10 with ammonia. The mixture was stirred at room temperature for 8 h to obtain an aqueous solution with flocculent precipitate. The solution was neutralized with glacial acetic acid and finally cooled and dried to obtain a white powder, which is the carbon dot@aminosilica composite material.

[0067] Polytetrahydrofuran diol and isophorone diisocyanate (IPDI) were dehydrated at 110°C and under a vacuum of ≤0.1MPa for 4 hours.

[0068] Under nitrogen atmosphere protection, 14g of dried polytetrahydrofuran diol and 12g of isophorone diisocyanate (IPDI) were added to a four-necked flask equipped with a thermometer, a PTFE stirring paddle, and a reflux condenser. The mixture was reacted at 50°C for 20 min, and then the temperature was raised to 90°C to continue the reaction for 2 h.

[0069] Add 1.2g of 1,4-butanediol, 0.01g of dibutyltin dilaurate and 50g of acetone, react at 80℃ for 2min, then add 2.0g of 2,2-dimethylolbutyric acid and react at 80℃ for 2h to generate a polyurethane prepolymer;

[0070] After cooling to 60°C, 0.307g of carbon dot@amino silica composite powder was added to 10g of acetone and ultrasonically dispersed for 4 hours.

[0071] Cool to 30℃, add 1.5g of triethylamine, and react for 30 minutes;

[0072] Add 140 mL of ultrapure water and disperse at high speed for 30 min. Remove acetone in a rotary evaporator at 50 °C to obtain an ultra-long phosphorescence lifetime waterborne polyurethane emulsion (NSi-CNDs-WPU) based on amino silica-confined carbon dots. 1.0 The fluorescent waterborne polyurethane prepared in this embodiment emits blue fluorescence under 365nm ultraviolet light irradiation and emits green phosphorescence after the ultraviolet light is turned off.

[0073] Example 5

[0074] Ethylenediamine was dissolved in deionized water, and then phosphoric acid was slowly added to the ethylenediamine aqueous solution and stirred for 10 min. The resulting clear solution was heated in a 750 W microwave oven for 130 s. After the sample cooled to room temperature, deionized water was added to the sample to form a pale yellow solution. The aqueous solution was centrifuged for 10 min to remove precipitates. The supernatant was filtered through a 0.22 μm membrane and neutralized with sodium carbonate. The supernatant was collected and dialyzed for 24 h (MWCO: 500 Da). Finally, it was freeze-dried to obtain a pale yellow solid carbon dot powder.

[0075] Carbon dot powder is dissolved in a certain amount of deionized water, and tetraethoxysilane (TEOS) is added and dispersed in the deionized water to form an aqueous solution. The pH is adjusted to 9-10 with ammonia water, and after stirring at room temperature for 16 hours, a colorless and transparent solution is formed, which is the water-soluble phosphorescent carbon dot.

[0076] (3-aminopropyl)-trimethoxysilane was dissolved in deionized water and sonicated for 10 min. The aqueous solution coated with silica was added, and the pH was adjusted to 9-10 with ammonia. The mixture was stirred at room temperature for 8 h to obtain an aqueous solution with flocculent precipitate. The solution was neutralized with glacial acetic acid and finally cooled and dried to obtain a white powder, which is the carbon dot@aminosilica composite material.

[0077] Polytetrahydrofuran diol and isophorone diisocyanate (IPDI) were dehydrated at 110°C and under a vacuum of ≤0.1MPa for 4 hours.

[0078] Under nitrogen atmosphere protection, 14g of dried polytetrahydrofuran diol and 12g of isophorone diisocyanate (IPDI) were added to a four-necked flask equipped with a thermometer, a PTFE stirring paddle, and a reflux condenser. The mixture was reacted at 50°C for 20 min, and then the temperature was raised to 90°C to continue the reaction for 2 h.

[0079] Add 1.2g of 1,4-butanediol, 0.01g of dibutyltin dilaurate and 50g of acetone, and react at 80℃ for 2h. Then add 2.0g of 2,2-dimethylolbutyric acid and react at 80℃ for 2h to generate a polyurethane prepolymer.

[0080] After cooling to 60°C, 0.921g of carbon dot@amino silica composite powder was added to 10g of acetone and ultrasonically dispersed for 4 hours.

[0081] Cool to 30℃, add 1.5g of triethylamine, and react for 30 minutes;

[0082] Add 140 mL of ultrapure water and disperse at high speed for 30 min. Remove acetone in a rotary evaporator at 50 °C to obtain an ultra-long phosphorescence lifetime waterborne polyurethane emulsion (NSi-CNDs-WPU) based on amino silica-confined carbon dots. 3.0 The fluorescent waterborne polyurethane prepared in this embodiment emits blue fluorescence under 365nm ultraviolet light irradiation and emits green phosphorescence after the ultraviolet light is turned off.

[0083] Example 6

[0084] Ethylenediamine was dissolved in deionized water, and then phosphoric acid was slowly added to the ethylenediamine aqueous solution and stirred for 10 min. The resulting clear solution was heated in a 750 W microwave oven for 130 s. After the sample cooled to room temperature, deionized water was added to the sample to form a pale yellow solution. The aqueous solution was centrifuged for 10 min to remove precipitates. The supernatant was filtered through a 0.22 μm membrane and neutralized with sodium carbonate. The supernatant was collected and dialyzed for 24 h (MWCO: 500 Da). Finally, it was freeze-dried to obtain a pale yellow solid carbon dot powder.

[0085] Carbon dot powder is dissolved in a certain amount of deionized water, and tetraethoxysilane (TEOS) is added and dispersed in the deionized water to form an aqueous solution. The pH is adjusted to 9-10 with ammonia water, and after stirring at room temperature for 16 hours, a colorless and transparent solution is formed, which is the water-soluble phosphorescent carbon dot.

[0086] (3-aminopropyl)-trimethoxysilane was dissolved in deionized water and sonicated for 10 min. The aqueous solution coated with silica was added, and the pH was adjusted to 9-10 with ammonia. The mixture was stirred at room temperature for 8 h to obtain an aqueous solution with flocculent precipitate. The solution was neutralized with glacial acetic acid and finally cooled and dried to obtain a white powder, which is the carbon dot@aminosilica composite material.

[0087] Polytetrahydrofuran diol and isophorone diisocyanate (IPDI) were dehydrated at 110°C and under a vacuum of ≤0.1MPa for 4 hours.

[0088] Under nitrogen atmosphere protection, 14g of dried polytetrahydrofuran diol and 12g of isophorone diisocyanate (IPDI) were added to a four-necked flask equipped with a thermometer, a PTFE stirring paddle, and a reflux condenser. The mixture was reacted at 50°C for 20 min, and then the temperature was raised to 90°C to continue the reaction for 2 h.

[0089] Add 1.2g of 1,4-butanediol, 0.01g of dibutyltin dilaurate and 50g of acetone, and react at 80℃ for 2h. Then add 2.0g of 2,2-dimethylolbutyric acid and react at 80℃ for 2h to generate a polyurethane prepolymer.

[0090] After cooling to 60°C, 0.921g of carbon dot@amino silica composite powder was added to 10g of acetone and ultrasonically dispersed for 4 hours.

[0091] Cool to 30℃, add 1.5g of triethylamine, and react for 30 minutes;

[0092] Add 140 mL of ultrapure water and disperse at high speed for 30 min. Remove acetone in a rotary evaporator at 50 °C to obtain the ultra-long phosphorescence lifetime waterborne polyurethane emulsion (NSi-CNDs-WPU) based on carbon dots@amino silica. 3.0 The fluorescent waterborne polyurethane prepared in this embodiment emits blue fluorescence under 365nm ultraviolet light irradiation and emits green phosphorescence after the ultraviolet light is turned off.

[0093] The obtained NSi-CNDs-WPU 3.0 The emulsion is uniformly coated onto a clean glass or polyester substrate, with the film thickness controlled at approximately 0.2–0.5 mm. It is then allowed to air dry at room temperature or dried at a low temperature to obtain a transparent, uniform luminescent polyurethane film. This film emits blue fluorescence under 365 nm ultraviolet light and exhibits a green phosphorescent afterglow when the light source is turned off.

[0094] Using stencil printing or mask spraying, NSi-CNDs-WPU 3.0 The emulsion is coated onto a transparent substrate in a predetermined pattern (such as a QR code or digital pattern), and after drying, it forms a luminescent pattern with photoresponsive properties. The resulting pattern displays a blue fluorescent image under ultraviolet irradiation, and transforms into a green phosphorescent image after the ultraviolet light source is turned off. The afterglow, visible to the naked eye, lasts for approximately 9 seconds.

[0095] The luminescent film or pattern can be used in the fields of information encryption and anti-counterfeiting identification. For example... Figure 6 As shown, it is composed of NSi-CNDs-WPU 3.0 The constructed dynamic QR code exhibits a distinct blue fluorescent pattern under 368nm UV excitation and displays green phosphorescence after the UV lamp is turned off, forming a sharp contrast with the blank WPU control area which shows no phosphorescence response. Its phosphorescence has an afterglow duration of approximately 10 seconds as observed by the naked eye, demonstrating good anti-counterfeiting identification capabilities. By controlling the UV irradiation and extinguishing process, NSi-CNDs-WPU... 3.0 The digital anti-counterfeiting pattern can achieve reversible conversion between blue fluorescent "8888" and green phosphorescent "6320", thereby realizing the dynamic display and concealed identification functions of multi-level information.

[0096] The above description is merely a preferred embodiment of the present invention and is illustrative rather than restrictive. Those skilled in the art will understand that many changes, modifications, and even equivalents can be made within the spirit and scope defined by the claims of the present invention, all of which will fall within the protection scope of the present invention.

Claims

1. A process for the preparation of aminosilica confined carbon dots based waterborne polyurethane with ultra-long phosphorescence lifetime, characterized in that, The method comprises the following steps: S1, using phosphoric acid and ethylenediamine as raw materials to synthesize carbon dot powder in pure water solvent; S2, according to Stober method, the carbon dot powder is limited in the silica encapsulation layer to obtain water-soluble phosphorescent carbon dots; S3, using (3-aminopropyl)-trimethoxysilane to modify the water-soluble phosphorescent carbon dots obtained in step S2 to obtain carbon dot@amino silica composite material; S4, under the atmosphere of nitrogen, the isocyanate and polyol after dehydration treatment are reacted at 50-60 DEG C for 20-30 min, then heated to 80-90 DEG C and continue to react for 2-3 h, then add dihydric alcohol chain extender and catalyst, react at 70-80 DEG C for 2-3 h, then add hydrophilic chain extender and react at 60-80 DEG C for 2-3 h, to generate polyurethane prepolymer; S5, after the reaction system in step S4 is cooled to 40-60 DEG C, add carbon dot@amino silica composite material ultrasonically dispersed in organic solvent and react for 3-4 h, then cool to 30-40 DEG C, add neutralizing agent and react for 30-40 min, then add ultrapure water and disperse at high speed for 20-30 min, in a rotary evaporator, remove solvent at 50-60 DEG C to obtain carbon dot@amino silica-based ultralong phosphorescent lifetime waterborne polyurethane emulsion.

2. The method for preparing an ultralong phosphorescence lifetime waterborne polyurethane based on amino silica-confined carbon dots as described in claim 1, characterized in that, In the step S1, the specific process is as follows: ethylenediamine is dissolved in deionized water, then phosphoric acid is slowly added into the ethylenediamine aqueous solution and stirred for 10 min, the transparent solution is heated in a 750 W microwave oven for 130, after the sample is cooled to room temperature, deionized water is added to form a light yellow solution, the aqueous solution is centrifuged for 10 min to remove precipitates, the supernatant is filtered through a 0.22 μm membrane, then neutralized with sodium carbonate, the supernatant is collected, dialyzed for 24 h, the MWCO is 500 Da during dialysis, and finally freeze-dried to obtain carbon dot powder.

3. The method for preparing an ultralong phosphorescence lifetime waterborne polyurethane based on amino silica-confined carbon dots as described in claim 1, characterized in that, In the step S2, the specific process is as follows: the carbon dot powder is dissolved in deionized water, tetraethoxysilane is dispersed in deionized water to form an aqueous solution, the pH is adjusted to 9-10 with ammonia water, and a colorless transparent solution is formed after stirring at room temperature for 16 h, which is water-soluble phosphorescent carbon dots.

4. The method of claim 1, wherein the method of preparing aminosilica-confined carbon dot-based waterborne polyurethane with ultra-long phosphorescent lifetime is characterized by, In the step S3, the specific process is as follows: (3-aminopropyl)-trimethoxysilane is dissolved in deionized water and ultrasonically treated for 10 min, the silica-coated aqueous solution is added, the pH is adjusted to 9-10 with ammonia water, and stirring is carried out at room temperature for 8 h to obtain an aqueous solution with flocculent precipitates, then neutralized with glacial acetic acid, and finally freeze-dried to obtain white powder, which is carbon dot@amino silica composite material.

5. The method of claim 1, wherein the method of preparing aminosilica-confined carbon dot-based waterborne polyurethane with ultra-long phosphorescent lifetime is characterized by, In the step S4, the isocyanate is one or more of toluene diisocyanate, 1,6-hexane diisocyanate, 4,4-diphenylmethane diisocyanate, isophorone diisocyanate, 1,5-naphthalene diisocyanate, polymethylene polyphenyl polyisocyanate, methylcyclohexyl diisocyanate, and dicyclohexylmethane diisocyanate, accounting for 5-30% of the total weight of the polyurethane prepolymer.

6. The method for preparing an ultralong phosphorescence lifetime waterborne polyurethane based on amino silica-confined carbon dots as described in claim 1, characterized in that, The polymer polyol in the step S4 is one or more of polybutadiene diol, polyoxypropylene diol, tetrahydrofuran-oxypropylene copolymer diol, polybutadiene-acrylonitrile diol, polyethylene adipate diol, polycarbonate 1,6-hexanediol diol, polyethylene adipate-propylene glycol diol, polyethylene adipate diethylene glycol diol, polytetrahydrofuran diol, polyadipic acid castor oil diol, polycaprolactone diol, and polyadipic acid-1,4-butanediol diol, accounting for 20-50% of the total weight of the polyurethane prepolymer.

7. The method for preparing an ultralong phosphorescence lifetime waterborne polyurethane based on amino silica-confined carbon dots as described in claim 1, characterized in that, The dehydration treatment in the step S4 is specifically as follows: the isocyanate and the polymer polyol are subjected to dehydration treatment at 110-120°C and a vacuum degree of ≤0.1 MPa for 4 hours.

8. The method of claim 1, wherein the method of preparing aminosilica-confined carbon dot-based waterborne polyurethane with ultra-long phosphorescent lifetime is characterized by, The dihydric alcohol chain extender in the step S4 is one or more of ethylene glycol (EG), diethylene glycol (DEG), dipropylene glycol (DPG), 1,2-propanediol (1,2-PG), 1,4-butanediol (BDO), neopentyl glycol (NPG), and 1,6-hexanediol (HD), accounting for 0-7% of the total weight; the catalyst is one or more of organic tin and tertiary amine catalysts, accounting for 0.01-0.03% of the total weight of the polyurethane prepolymer; and the hydrophilic chain extender is 2,2-dihydroxybutyric acid or 2,2-dihydroxypropionic acid, accounting for 5-8% of the total weight of the polyurethane prepolymer.

9. The method of claim 1, wherein the method of preparing aminosilica-confined carbon dot-based waterborne polyurethane with ultra-long phosphorescent lifetime is characterized by, The organic solvent in the step S5 is one or more of acetone, butanone, cyclohexanone, tetrahydrofuran, dimethyl sulfoxide, N,N-dimethylformamide, toluene, dioxane, and ethyl acetate, accounting for 20-40% of the total weight of the polyurethane prepolymer; and the neutralizing agent is one or more of triethylamine, sodium hydroxide, aqueous ammonia, sodium bicarbonate, and potassium hydroxide, accounting for 5-8% of the total weight of the polyurethane prepolymer.

10. An amino-silica-limited carbon dot-based waterborne polyurethane with super-long phosphorescent lifetime, prepared by the method of any one of claims 1-9.

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