CN108822527A - The modified aqueous polyurethane nano composite material and preparation method of carbon quantum dot - Google Patents

Abstract

The invention relates to a water-based polyurethane nanocomposite material modified by carbon quantum dots and a preparation method thereof. Firstly, carbon quantum dots containing active groups amino groups and hydroxyl groups are prepared on the surface, and then the reaction of the amino group, hydroxyl group and isocyanate groups in the water-based polyurethane prepolymer is used. Finally, the in-situ polymerization method is used to compound carbon quantum dots and water-based polyurethane to prepare carbon quantum dot-modified water-based polyurethane fluorescent nanocomposites, which are easy to operate, safe and environmentally friendly, and promote the development of sustainable and eco-friendly materials. Effective Expand the application range of carbon quantum dots and water-based polyurethane materials.

Description

Waterborne polyurethane nanocomposite material modified by carbon quantum dots and preparation method thereof

technical field

The invention belongs to the technical field of production of functional nanocomposite materials, and in particular relates to a waterborne polyurethane nanocomposite material modified by carbon quantum dots and a preparation method thereof.

Background technique

Carbon quantum dots (Carbon dots or CQDs) are a new carbon nanomaterial after graphene, carbon nanotubes, and fullerenes. The particle size is generally less than 10nm. Due to its low synthesis cost, the prepared carbon Quantum dots have good optical stability, low toxicity, and easy surface functionalization. Compared with inorganic quantum dots containing toxic heavy metals, carbon quantum dots are more environmentally friendly and biocompatible. Furthermore, carbon quantum dots offer a facile preparation route by using nontoxic chemicals, environmentally friendly solvents, and renewable precursors, which is consistent with the principle of green chemistry. Therefore, it has received extensive attention in the fields of biosensing and probes, bioimaging, LED devices, photocatalysis, and fluorescent inks.

The synthesis of carbon quantum dots and the preparation of functional polymers are two fields in which modern material chemistry has achieved great success. In recent years, focusing on combining the advantages of carbon quantum dots and polymers to prepare new functional composite materials has attracted more and more attention. Water-based polyurethane material is a kind of polymer material with relatively mature research, which conforms to the "three prerequisites" of industrial development (resource RESOURCE, energy ENERGY, pollution-free POLLUTION-FREE) and "4E" principles (economic ECONOMY, efficiency EFFICIENCY, ecological ECOLOGY , energy ENERGY), its optical transparency is good, the synthesis method is simple and the mechanical properties of the material can be adjusted by adjusting the ratio of hard segment and soft segment.

Contents of the invention

The purpose of the present invention is to provide a carbon quantum dot modified water-based polyurethane nanocomposite material and a preparation method thereof. The material has good fluorescence performance and can effectively expand the application range of carbon quantum dots and water-based polyurethane materials.

The technical scheme adopted in the present invention is:

The preparation method of the waterborne polyurethane nano-composite material modified by carbon quantum dots is characterized in that:

Achieved by the following steps:

First prepare carbon quantum dots with active groups amino groups and hydroxyl groups on the surface, then use the reaction of amino groups, hydroxyl groups and isocyanate groups in the water-based polyurethane prepolymer, and finally use the in-situ polymerization method to compound carbon quantum dots with water-based polyurethane to prepare Waterborne polyurethane fluorescent nanocomposites modified with carbon quantum dots.

The preparation method of the waterborne polyurethane nanocomposite material modified by described carbon quantum dots is characterized in that:

Specific steps include:

Step 1: Preparation of carbon quantum dots:

Add 2g of citric acid and 1g of urea to 50mL of distilled water, fully dissolve to obtain a transparent solution; then transfer the mixed solution to a hydrothermal reaction kettle with a polytetrafluoroethylene liner, and place it in an oven for hydrothermal reaction , cooled naturally to room temperature to obtain a water-soluble carbon quantum dot dispersion with amino and hydroxyl groups on the surface, and then the dispersion was centrifuged and dialyzed to obtain a carbon quantum dot solution with good storage stability; finally the resulting solution was Freeze-drying to obtain dry samples in polymer-like form;

Step 2: Preparation of carbon quantum dots-waterborne polyurethane nanocomposites:

Add isophorone diisocyanate, polypropylene glycol, dibutyltin dilaurate, and small molecule chain extender 1,4-butanediol into a three-necked flask equipped with a thermometer, a stirrer, and a glass bottle stopper, mix well, and heat up The polyurethane prepolymer is prepared by reaction; the molar ratio of isophorone diisocyanate to polypropylene glycol is 3~5, the amount of dibutyltin dilaurate is 2~4 drops, and the amount of 1,4-butanediol is isophorone 2% of the sum of the mass of ketone diisocyanate and polypropylene glycol;

Then add the hydrophilic chain extender bismethylol propionic acid to heat up and carry out the chain extension reaction, then add the carbon quantum dots dispersed in the solvent prepared in step 1, and continue the chain extension reaction; finally the obtained product is carried out and emulsification to obtain carbon quantum dots-waterborne polyurethane fluorescent emulsion; the amount of bismethylol propionic acid is 3%~7% of the sum of isophorone diisocyanate and polypropylene glycol quality, and the amount of carbon quantum dots is isophorone 0.05%~0.25% of the sum of mass of ketone diisocyanate and polypropylene glycol.

In step 1, the mixed solution was transferred to a hydrothermal reaction kettle with a polytetrafluoroethylene liner, and placed in an oven at 160° C. for hydrothermal reaction for 6 hours.

In step 2, the prepolymerization reaction temperature and time are 50°C for 20 minutes first, and 60~70°C for 1~2h.

In step 2, the chain extension reaction temperature of adding the hydrophilic chain extender bismethylolpropionic acid is 80°C, and the reaction time is 1.5~2.5h.

In step 2, the chain extension reaction temperature of adding carbon quantum dots is 80°C, and the reaction time is 1~2h.

In step 2, the solvent used to disperse the carbon quantum dots is dimethyl sulfoxide, acetone or N-methylpyrrolidone.

The carbon quantum dot modified waterborne polyurethane nanocomposite material prepared as described preparation method.

The present invention has the following advantages:

1. The present invention adopts a one-step hydrothermal method to successfully prepare fluorescent carbon quantum dots with amino and hydroxyl groups on the surface, and endows them with active site amino groups and hydroxyl groups as multifunctional chain extenders. The operation route is simple, low in cost and environmentally friendly , consistent with the principle of green chemistry.

2. As a multifunctional chain extender, carbon quantum dots are introduced into the waterborne polyurethane matrix by chemical bonding. On the one hand, the aromatic carbonization structure of carbon quantum dots with highly polar peripheral groups endows them with strong physical and chemical interactions with the waterborne polyurethane matrix. interaction, thereby enhancing the mechanical properties of the waterborne polyurethane film. On the other hand, the quantum size of carbon quantum dots and good compatibility with waterborne polyurethane matrix help to maintain the transparency of pristine polyurethane film, which is difficult to achieve with other carbon nanostructures.

3. Water-based polyurethane uses water as a dispersant, which is safe and environmentally friendly, and promotes the development of sustainable and eco-friendly materials.

Description of drawings

Fig. 1 is a schematic diagram of the synthesis process of carbon quantum dots-waterborne polyurethane of the present invention.

Fig. 2 is a schematic diagram of the synthesis mechanism of carbon quantum dots-waterborne polyurethane of the present invention.

Figure 3 is the infrared image of the waterborne polyurethane prepolymer (PPU) and carbon quantum dots-waterborne polyurethane prepolymer (CQDs-PPU) obtained in Example 2.

Figure 4 is a photo of the transparent appearance of the carbon quantum dot-waterborne polyurethane (CQDs-WPU) film obtained in Example 2.

Fig. 5 is a photo of carbon quantum dots (CQDs) and carbon quantum dots-waterborne polyurethane (CQDs-WPU) film obtained in Example 2 under natural light and ultraviolet light.

Detailed ways

The present invention will be described in detail below in combination with specific embodiments.

The present invention aims to explore the composite behavior of carbon quantum dots (CQDs) and waterborne polyurethane (WPU), first directly obtain fluorescent CQDs with amino and hydroxyl groups on the surface through a one-step hydrothermal method, and then use them as multifunctional chain extenders , using the _-NH2 and -OH groups on the surface of CQDs as active sites, introduced into the WPU matrix by chemical bonding, and prepared CQDs-modified WPU fluorescent nanocomposites by in-situ polymerization, promoting sustainable and eco-friendly Material development.

The invention relates to a method for preparing a water-based polyurethane nanocomposite material modified by carbon quantum dots. Firstly, carbon quantum dots containing active groups amino groups and hydroxyl groups are prepared on the surface, and then the amino groups, hydroxyl groups and isocyanate groups in the water-based polyurethane prepolymer are used. reaction, and finally adopt the in-situ polymerization method to compound the carbon quantum dots and water-based polyurethane, so as to prepare the carbon quantum dot-modified water-based polyurethane fluorescent nanocomposite material.

Specific steps include:

Step 1: Preparation of carbon quantum dots:

Add 2g of citric acid and 1g of urea to 50mL of distilled water, fully dissolve to obtain a transparent solution; then transfer the mixed solution to a hydrothermal reaction kettle with a polytetrafluoroethylene liner, and place it in an oven for hydrothermal reaction , cooled naturally to room temperature to obtain a water-soluble carbon quantum dot dispersion with amino and hydroxyl groups on the surface, and then the dispersion was centrifuged and dialyzed to obtain a carbon quantum dot solution with good storage stability; finally the resulting solution was Freeze-drying to obtain dry samples in polymer-like form;

Step 2: Preparation of carbon quantum dots-waterborne polyurethane nanocomposites:

Add isophorone diisocyanate, polypropylene glycol, dibutyltin dilaurate, and small molecule chain extender 1,4-butanediol into a three-necked flask equipped with a thermometer, a stirrer, and a glass bottle stopper, mix well, and heat up The polyurethane prepolymer is prepared by reaction; the molar ratio of isophorone diisocyanate to polypropylene glycol is 3~5, the amount of dibutyltin dilaurate is 2~4 drops, and the amount of 1,4-butanediol is isophorone 2% of the sum of ketone diisocyanate and polypropylene glycol quality;

Then add the hydrophilic chain extender bismethylol propionic acid to heat up and carry out the chain extension reaction, then add the carbon quantum dots dispersed in the solvent prepared in step 1, and continue the chain extension reaction; finally the obtained product is carried out and emulsification to obtain carbon quantum dots-waterborne polyurethane fluorescent emulsion; the amount of bismethylol propionic acid is 3%~7% of the sum of isophorone diisocyanate and polypropylene glycol quality, and the amount of carbon quantum dots is isophorone 0.05%~0.25% of the sum of mass of ketone diisocyanate and polypropylene glycol.

In step 1, the mixed solution was transferred to a hydrothermal reaction kettle with a polytetrafluoroethylene liner, and placed in an oven at 160° C. for hydrothermal reaction for 6 hours.

In step 2, the prepolymerization reaction temperature and time are 50°C for 20 minutes first, and 60~70°C for 1~2h.

In step 2, the chain extension reaction temperature of adding the hydrophilic chain extender bismethylolpropionic acid is 80°C, and the reaction time is 1.5~2.5h.

In step 2, the chain extension reaction temperature of adding carbon quantum dots is 80°C, and the reaction time is 1~2h.

In step 2, the solvent used to disperse the carbon quantum dots is dimethyl sulfoxide, acetone or N-methylpyrrolidone.

The waterborne polyurethane nanocomposite material modified by carbon quantum dots prepared by the preparation method can be used in the fields of coating, anti-counterfeiting marks, optical storage materials and the like.

Example 1:

Step (1): Preparation of carbon quantum dots (CQDs)

Add 2g of citric acid and 1g of urea into 50mL of distilled water, fully dissolve to obtain a transparent solution. Then transfer the mixed solution to a hydrothermal reaction kettle with a polytetrafluoroethylene liner, place it in an oven at 160°C for hydrothermal reaction for 6 hours, and cool it to room temperature naturally to obtain a surface with amino and hydroxyl groups. Agglomerated water-soluble carbon quantum dot dispersion, and then the dispersion is centrifuged and dialyzed to obtain a carbon quantum dot (CQDs) solution with good storage stability. Finally, the resulting solution was freeze-dried to obtain a dry sample in a polymer-like form.

Step (2): Preparation of carbon quantum dots-waterborne polyurethane (CQDs-WPU) nanocomposites

Add 40 mmol of isophorone diisocyanate (IPDI), 10 mmol of polypropylene glycol (PPG), 2 drops of dibutyltin dilaurate (DBTDL), and 4.22 mmol of small molecule chain extender 1,4-butanediol (BDO) to the In a three-necked flask with a thermometer, a stirrer, and a glass bottle stopper, mix well, raise the temperature to 50°C and react for 20 minutes, then continue to react at 60°C for 2 hours to obtain a polyurethane prepolymer. Then add 8.42mmol dimethylolpropionic acid (DMPA) and heat up to 80°C for 1.5h of reaction, then add 0.05% fluorescent carbon quantum dots (dispersed in acetone) prepared in step (1) as a chain extender, 80 ℃ to continue the chain extension reaction for 1h. Finally, the prepared product was neutralized and emulsified to obtain a carbon quantum dot-waterborne polyurethane (CQDs-WPU) fluorescent emulsion.

Example 2:

Step (1): Preparation of carbon quantum dots (CQDs)

Add 2g of citric acid and 1g of urea into 50mL of distilled water, fully dissolve to obtain a transparent solution. Then transfer the mixed solution to a hydrothermal reaction kettle with a polytetrafluoroethylene liner, place it in an oven at 160°C for hydrothermal reaction for 6 hours, and then cool it to room temperature naturally to obtain the surface with amino and hydroxyl groups. Fluorescent carbon quantum dot dispersion of the group, and then the dispersion is centrifuged and dialyzed to obtain a carbon quantum dot (CQDs) solution with good storage stability. Finally, the resulting solution was freeze-dried to obtain a dry sample in a polymer-like form.

Step (2): Preparation of carbon quantum dots-waterborne polyurethane (CQDs-WPU) nanocomposites

Add 40 mmol of isophorone diisocyanate (IPDI), 13 mmol of polypropylene glycol (PPG), 2 drops of dibutyltin dilaurate (DBTDL), and 3.28 mmol of small molecule chain extender 1,4-butanediol (BDO) to the In a three-necked flask with a thermometer, a stirrer, and a glass bottle stopper, mix well, raise the temperature to 50°C and react for 20 minutes, then continue to react at 70°C for 1 hour to prepare a polyurethane prepolymer. Then add 8.28mmol dimethylol propionic acid (DMPA) and raise the temperature to 80°C for 2.5h of reaction, and then add 0.15% fluorescent carbon quantum dots (dispersed in dimethyl sulfoxide) prepared in step (1) as an amplifier. Chain agent, continue the chain extension reaction at 80°C for 1.5h. Finally, the prepared product was neutralized and emulsified to obtain a carbon quantum dot-waterborne polyurethane (CQDs-WPU) fluorescent emulsion.

Figure 3 is the infrared image of the waterborne polyurethane prepolymer (PPU) and carbon quantum dots-waterborne polyurethane prepolymer (CQDs-PPU) obtained in Example 2. It can be seen that after adding different mass fractions of carbon quantum dots, they are located at 2263 cm ^- The strong absorption peak of the isocyanate group near ¹ is obviously weakened, indicating that the amino group and hydroxyl group have undergone addition reaction with the residual isocyanate functional group in the prepolymer. When more carbon quantum dots are added, the absorption peak of the isocyanate group is significantly weakened, which shows that the amino and hydroxyl groups on the surface of carbon quantum dots participate in the reaction, and confirms that carbon quantum dots are formed by chemical bonds. in a polyurethane matrix.

Figure 4 is a photo of the transparent appearance of the carbon quantum dot-waterborne polyurethane (CQDs-WPU) film obtained in Example 2, indicating that the carbon quantum dot-waterborne polyurethane (CQDs-WPU) film prepared by this patent retains the transparency of the original waterborne polyurethane film , which is due to the quantum size of carbon quantum dots and the good compatibility with the polyurethane matrix.

Figure 5 is a photo of the carbon quantum dots (CQDs) and carbon quantum dots-waterborne polyurethane (CQDs-WPU) film obtained in Example 2 under natural light and ultraviolet light. It can be seen that under the ultraviolet light, carbon quantum dots-waterborne polyurethane Similar color changes to carbon quantum dots were also observed for the films.

Example 3:

Step (1): Preparation of carbon quantum dots (CQDs)

Add 2g of citric acid and 1g of urea into 50mL of distilled water, fully dissolve to obtain a transparent solution. Then transfer the mixed solution to a hydrothermal reaction kettle with a polytetrafluoroethylene liner, place it in an oven at 160°C for hydrothermal reaction for 6 hours, and naturally cool to room temperature to obtain a surface with amino and hydroxyl groups. Agglomerated water-soluble carbon quantum dot dispersion, and then the dispersion is centrifuged and dialyzed to obtain a carbon quantum dot (CQDs) solution with good storage stability. Finally, the resulting solution was freeze-dried to obtain a dry sample in a polymer-like form.

Step (2): Preparation of carbon quantum dots-waterborne polyurethane (CQDs-WPU) nanocomposites

Add 40 mmol of isophorone diisocyanate (IPDI), 8 mmol of polypropylene glycol (PPG), 3 drops of dibutyltin dilaurate (DBTDL), and 3.75 mmol of small molecule chain extender 1,4-butanediol (BDO) to the In a three-necked flask with a thermometer, a stirrer, and a glass bottle stopper, mix evenly, raise the temperature to 50°C for 20 minutes, and then continue to react for 1.5 hours at 60°C to obtain a polyurethane prepolymer. Then add 8.81mmol dimethylolpropionic acid (DMPA) and raise the temperature to 80°C for 2h reaction, then add 0.25% fluorescent carbon quantum dots (dispersed in N-methylpyrrolidone) prepared in step (1) as chain extension agent, and continue the chain extension reaction at 80°C for 2h. Finally, the prepared product was neutralized and emulsified to obtain a carbon quantum dot-waterborne polyurethane (CQDs-WPU) fluorescent emulsion.

Example 4:

Step (1): Preparation of carbon quantum dots (CQDs)

Add 2g of citric acid and 1g of urea into 50mL of distilled water, fully dissolve to obtain a transparent solution. Then transfer the mixed solution to a hydrothermal reaction kettle with a polytetrafluoroethylene liner, place it in an oven at 160°C for hydrothermal reaction for 6 hours, and cool it to room temperature naturally to obtain a surface with amino and hydroxyl groups. Agglomerated water-soluble carbon quantum dot dispersion, and then the dispersion is centrifuged and dialyzed to obtain a carbon quantum dot (CQDs) solution with good storage stability. Finally, the resulting solution was freeze-dried to obtain a dry sample in a polymer-like form.

Step (2): Preparation of carbon quantum dots-waterborne polyurethane (CQDs-WPU) nanocomposites

Add 40 mmol of isophorone diisocyanate (IPDI), 11.4 mmol of polypropylene glycol (PPG), 4 drops of dibutyltin dilaurate (DBTDL), 4.50 mmol of small molecule chain extender 1,4-butanediol (BDO) to the In a three-necked flask equipped with a thermometer, a stirrer, and a glass bottle stopper, mix well, raise the temperature to 50°C for 20 minutes, and then continue to react for 1.5 hours at 60°C to prepare a polyurethane prepolymer. Then add 9.08mmol dimethylolpropionic acid (DMPA) and heat up to 80°C for 2.5h of reaction, and then add 0.15% of the fluorescent carbon quantum dots (dispersed in dimethyl sulfoxide) prepared in step (1) as an amplifier. Chain agent, continue the chain extension reaction at 80°C for 1h. Finally, the prepared product was neutralized and emulsified to obtain a carbon quantum dot-waterborne polyurethane (CQDs-WPU) fluorescent emulsion.

Example 5:

Step (1): Preparation of carbon quantum dots (CQDs)

Add 2g of citric acid and 1g of urea into 50mL of distilled water, fully dissolve to obtain a transparent solution. Then transfer the mixed solution to a hydrothermal reaction kettle with a polytetrafluoroethylene liner, place it in an oven at 160°C for hydrothermal reaction for 6 hours, and cool it to room temperature naturally to obtain a surface with amino and hydroxyl groups. Agglomerated water-soluble carbon quantum dot dispersion, and then the dispersion is centrifuged and dialyzed to obtain a carbon quantum dot (CQDs) solution with good storage stability. Finally, the resulting solution was freeze-dried to obtain a dry sample in a polymer-like form.

Step (2): Preparation of carbon quantum dots-waterborne polyurethane (CQDs-WPU) nanocomposites

Add 40 mmol of isophorone diisocyanate (IPDI), 8.88 mmol of polypropylene glycol (PPG), 2 drops of dibutyltin dilaurate (DBTDL), 3.94 mmol of small molecule chain extender 1,4-butanediol (BDO) to the In a three-necked flask equipped with a thermometer, a stirrer, and a glass bottle stopper, mix well, raise the temperature to 50°C and react for 20 minutes, then continue to react at 70°C for 1 hour to prepare a polyurethane prepolymer. Then add 9.28mmol dimethylolpropionic acid (DMPA) and raise the temperature to 80°C for 2.5h, then add 0.25% fluorescent carbon quantum dots (dispersed in acetone) prepared in step (1) as a chain extender, 80 °C to continue the chain extension reaction for 1.5h. Finally, the prepared product was neutralized and emulsified to obtain a carbon quantum dot-waterborne polyurethane (CQDs-WPU) fluorescent emulsion.

The content of the present invention is not limited to the examples listed, and any equivalent transformation of the technical solution of the present invention adopted by those of ordinary skill in the art by reading the description of the present invention is covered by the claims of the present invention.

Claims (8)

1. the preparation method of the aqueous polyurethane nanocomposite material of carbon quantum dot modification, it is characterized in that: Achieved by the following steps: First prepare carbon quantum dots with active groups amino groups and hydroxyl groups on the surface, then use the reaction of amino groups, hydroxyl groups and isocyanate groups in the water-based polyurethane prepolymer, and finally use the in-situ polymerization method to compound carbon quantum dots with water-based polyurethane to prepare Waterborne polyurethane fluorescent nanocomposites modified with carbon quantum dots. 2. the preparation method of the water-based polyurethane nanocomposite material modified by carbon quantum dots according to claim 1, is characterized in that: Specific steps include: Step 1: Preparation of carbon quantum dots: Add 2g of citric acid and 1g of urea to 50mL of distilled water, fully dissolve to obtain a transparent solution; then transfer the mixed solution to a hydrothermal reaction kettle with a polytetrafluoroethylene liner, and place it in an oven for hydrothermal reaction , cooled naturally to room temperature to obtain a water-soluble carbon quantum dot dispersion with amino and hydroxyl groups on the surface, and then the dispersion was centrifuged and dialyzed to obtain a carbon quantum dot solution with good storage stability; finally the resulting solution was Freeze-drying to obtain dry samples in polymer-like form; Step 2: Preparation of carbon quantum dots-waterborne polyurethane nanocomposites: Add isophorone diisocyanate, polypropylene glycol, dibutyltin dilaurate, and small molecule chain extender 1,4-butanediol into a three-necked flask equipped with a thermometer, a stirrer, and a glass bottle stopper, mix well, and heat up The polyurethane prepolymer is prepared by reaction; the molar ratio of isophorone diisocyanate to polypropylene glycol is 3~5, the amount of dibutyltin dilaurate is 2~4 drops, and the amount of 1,4-butanediol is isophorone 2% of the sum of the mass of ketone diisocyanate and polypropylene glycol; Then add the hydrophilic chain extender bismethylol propionic acid to heat up and carry out the chain extension reaction, then add the carbon quantum dots dispersed in the solvent prepared in step 1, and continue the chain extension reaction; finally the obtained product is carried out and emulsification to obtain carbon quantum dots-waterborne polyurethane fluorescent emulsion; the amount of bismethylol propionic acid is 3%~7% of the sum of isophorone diisocyanate and polypropylene glycol quality, and the amount of carbon quantum dots is isophorone 0.05%~0.25% of the sum of mass of ketone diisocyanate and polypropylene glycol. 3. the preparation method of the waterborne polyurethane nanocomposite material modified by carbon quantum dots according to claim 2, is characterized in that: In step 1, the mixed solution was transferred to a hydrothermal reaction kettle with a polytetrafluoroethylene liner, and placed in an oven at 160° C. for hydrothermal reaction for 6 hours. 4. the preparation method of the waterborne polyurethane nanocomposite material modified by carbon quantum dots according to claim 2, is characterized in that: In step 2, the prepolymerization reaction temperature and time are 50°C for 20 minutes first, and 60~70°C for 1~2h. 5. the preparation method of the waterborne polyurethane nanocomposite material modified by carbon quantum dots according to claim 2, is characterized in that: In step 2, the chain extension reaction temperature of adding the hydrophilic chain extender bismethylolpropionic acid is 80°C, and the reaction time is 1.5~2.5h. 6. the preparation method of the waterborne polyurethane nanocomposite material modified by carbon quantum dots according to claim 2, is characterized in that: In step 2, the chain extension reaction temperature of adding carbon quantum dots is 80°C, and the reaction time is 1~2h. 7. the preparation method of the waterborne polyurethane nanocomposite material modified by carbon quantum dots according to claim 2, is characterized in that: In step 2, the solvent used to disperse the carbon quantum dots is dimethyl sulfoxide, acetone or N-methylpyrrolidone. 8. the waterborne polyurethane nano-composite material that the carbon quantum dot modification that preparation method as described in claim 1 or 2 makes.