CN116217883A

CN116217883A - Carbon quantum dot modified fluorescent waterborne polyurethane and preparation method thereof

Info

Publication number: CN116217883A
Application number: CN202310003101.3A
Authority: CN
Inventors: 谢亚典; 孙军坤; 孙小鹏; 张续
Original assignee: Wanhua Chemical Group Co Ltd
Current assignee: Wanhua Chemical Group Co Ltd
Priority date: 2023-01-03
Filing date: 2023-01-03
Publication date: 2023-06-06

Abstract

The invention provides carbon quantum dot modified fluorescent waterborne polyurethane and a preparation method thereof, wherein the fluorescent waterborne polyurethane comprises the following raw materials: polyisocyanate, polyol, carbon quantum dot, hydrophilic chain extender, neutralizer, post chain extender and water. The carbon quantum dots added in the invention have solid state luminescence property, serve as fluorescence centers, use polyether amine as a connecting structure and are distributed in a polyurethane main chain segment structure in a block mode. The fluorescent waterborne polyurethane provided by the invention has multicolor luminous capability, excellent rubbing color fastness and more excellent anti-counterfeiting effect.

Description

Carbon quantum dot modified fluorescent waterborne polyurethane and preparation method thereof

Technical Field

The invention relates to the technical field of water-based polyurethane polymer structure design and synthesis, in particular to carbon quantum dot modified fluorescent water-based polyurethane and a preparation method thereof.

Background

Along with the continuous enhancement of social copyright consciousness, higher requirements are also put forward on the anti-counterfeiting technology of products. The existing anti-counterfeiting method has various modes such as pressure sensitivity, heat sensitivity, photosensitive anti-counterfeiting and the like, and the physical properties of the anti-counterfeiting material are changed through different stimulus responses so as to achieve the effect of the anti-counterfeiting mark. Wherein fluorescent anti-counterfeiting is a simple and effective photosensitive anti-counterfeiting method.

Patent CN103102675a provides a preparation method of fluorescent polyurethane resin, which uses expensive rare earth element europium complex as fluorescent light-emitting center and can only emit monochromatic fluorescence. However, the common monochromatic fluorescence anti-counterfeiting has the defects of easy cracking, unstable fluorescent material, short service life and the like, and cannot meet the market demand, so that a more stable, reliable and difficult-to-crack fluorescence anti-counterfeiting method needs to be developed.

In many fields, the trend of polyurethane water conversion is that waterborne polyurethane is often used as surface coating for clothes, bags, ornaments and the like as surface coating or printing ink, so that the fluorescent waterborne polyurethane can be used for manufacturing anti-counterfeiting marks and creative designs. The preparation and application of the aqueous polyurethane material are very mature, and the key of the preparation of the fluorescent aqueous polyurethane is the preparation method of the fluorescent material and how to firmly combine the fluorescent material and the polyurethane stably. Patent CN200510112138.1 provides a screen printing fluorescent paint for color conversion and a preparation method thereof, wherein fluorescent dye and high polymer are directly blended together, but the fluorescent resin dye prepared by the method is not firmly combined with the high polymer, is easy to decolorize and is not resistant to solvent flushing.

Patent CN110330622a discloses a fluorescent water-based polyurethane and a preparation method thereof, which is obtained by mixing fluorescein and diisocyanate, and then performing prepolymerization and chain extension. However, the polyurethane can only emit single fluorescence, has no fluorescence regulation and control capability, is poor in color fastness, has higher biotoxicity of fluorescein, and provides higher protection requirements for operators.

The carbon quantum dot is a novel low-toxicity even nontoxic nano fluorescent material, and is spherical or spheroidic particles which take C element as a main component, have carbon cores of 1-20nm and are modified with rich organic functional groups on the surfaces, can be excited by light and generally have multicolor fluorescence emission. The surface of the polyurethane is easy to modify functional groups such as amino groups, hydroxyl groups and the like, so that the polyurethane can be grafted on a polyurethane polymer chain or used as a chain extension center of the polyurethane polymer in the process of pre-polymerizing or chain extension of the waterborne polyurethane, and a structure that carbon quantum dots are monodisperse in the polyurethane polymer is formed.

The carbon quantum dots also have unique fluorescence emission properties depending on excitation wavelength, and can be generally excited by light with different wavelengths to emit light with different wavelengths, unlike the traditional fluorescent materials with monochromatic emission, the carbon quantum dots can respond to the excitation of light with different wavelengths due to a plurality of fluorescent active centers of various types of the carbon quantum dots. And the carbon quantum dots modified by different particle diameters and different functional groups have different optical properties, so that the carbon quantum dots have more reliable anti-counterfeiting function due to the special properties.

However, in general, carbon quantum dots have no solid state light emitting property, and can have fluorescence emission capability only when in a monodisperse state, which is called "concentration quenching phenomenon", which limits the light emitting efficiency and maximum light emitting intensity of the carbon quantum dots in a polymer.

Disclosure of Invention

In order to obtain fluorescent aqueous polyurethane with stronger luminous capacity, carbon quantum dots which are not quenched by concentration need to be prepared. The invention aims to provide fluorescent water-based polyurethane modified by carbon quantum dots, which is not quenched by concentration, and has multicolor fluorescence emission property and excellent water washing resistance and alcohol washing resistance.

The invention also aims to provide a preparation method of the fluorescent water-based polyurethane modified by the carbon quantum dots without concentration quenching.

In order to achieve the above object, the present invention adopts the following technical scheme:

the fluorescent water-based polyurethane modified by the carbon quantum dots is prepared from the following raw materials:

(a) A polyisocyanate;

(b) A polyol;

(c) Carbon quantum dots;

(d) Hydrophilic chain extenders;

(e) A neutralizing agent;

(f) A rear chain extender;

(g) And (3) water.

In a specific embodiment, the fluorescent waterborne polyurethane is prepared from the following raw materials in parts by weight:

(a) 5-15 parts, preferably 6-9 parts, of polyisocyanate;

(b) 15-30 parts, preferably 18-24 parts, of a polyol;

(c) 0.1 to 0.9 part, preferably 0.15 to 0.5 part, of carbon quantum dots;

(d) 0.3 to 1.5 parts, preferably 0.5 to 1 part, of hydrophilic chain extender;

(e) 0.3 to 1.5 parts, preferably 0.5 to 1 part, of neutralizing agent;

(f) 0.1 to 1 part, preferably 0.2 to 0.5 part, of a rear chain extender;

(g) 50-80 parts of water, preferably 60-70 parts.

In a specific embodiment, the carbon quantum dots are solid powder, the particle size is 1-20nm, and the number average molecular weight is 2000-10000.

In a specific embodiment, the carbon quantum dot is prepared from a carbon source, ethylenediamine and polyetheramine, wherein the carbon source accounts for 70-90% of the total mass, the ethylenediamine accounts for 5-20% of the total mass, and the polyetheramine accounts for 5-10% of the total mass.

In a specific embodiment, the carbon source structure is as shown in formula (I); preferably, the carbon source is prepared by reacting 4,4 '-dicyano methyl triphenylamine with 4,4' -dialdehyde tetraphenyl ethylene or a derivative thereof.

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In a specific embodiment, the polyetheramine has a molecular weight of 500 to 4000, preferably 600 to 1000.

In a specific embodiment, the preparation method of the carbon quantum dot comprises the following steps:

1) Solid phase reaction: dissolving a carbon source in tetrahydrofuran, then rapidly adding sodium methoxide into the solution, uniformly dispersing the solution, performing reduced pressure distillation to remove the tetrahydrofuran, rapidly transferring the powder into a reaction kettle, adding ethylenediamine into the reaction kettle, and placing the reaction kettle in an oven at 180-240 ℃ for reaction for 4-12 hours;

2) Solvothermal reaction: dissolving the powder obtained by the solid phase reaction in tetrahydrofuran, adding polyether amine into the tetrahydrofuran, and placing the mixture in a baking oven at 180-240 ℃ for reaction for 4-12h;

3) Purifying: adjusting the pH of the solvothermal reaction mixture to be neutral by using hydrochloric acid, dissolving the mixture in water, centrifuging, taking supernatant, filtering, purifying by column chromatography or dialysis, and finally freeze-drying the dialyzate to obtain carbon quantum dot powder.

In a specific embodiment, the centrifuge speed in step 3) is 10000-20000 rpm and the pore size of the filter membrane used for filtration is 0.2 μm; preferably, the solvent used for column chromatography purification is one or more of methanol, dichloromethane, n-hexane and toluene, and silica gel is 100-300 meshes; the molecular weight of a dialysis bag used for dialysis and purification is 2000-10000, and the dialyzate is one or more of water, ethanol and toluene; preferably, the volume of the dialysate is 30-100 times that of the dialysate to be dialyzed, and stirring is carried out during dialysis, and the rotating speed of the rotor is 200-800 rpm; more preferably, the dialysate is replaced every 8 to 12 hours, 3 to 5 times in total.

In a specific embodiment, the fluorescent aqueous polyurethane can emit light in a solid state into fluorescent light with various colors, has fluorescence emission capability depending on excitation wavelength, and has an excitation wavelength range of 200-500nm and a fluorescence emission range of 300-800nm.

On the other hand, the preparation method of the fluorescent water-based polyurethane comprises the following steps:

a) Placing polyisocyanate into a three-neck flask, metering polyol, a hydrophilic chain extender and a proper amount of catalyst, uniformly dispersing, heating to 70-90 ℃, continuously stirring, and keeping for 2-4h;

b) Adding carbon quantum dots into the mixture, and reacting for 2 hours at 60-80 ℃;

c) And (3) cooling to 5-35 ℃, adding acetone, adding water for dispersion, adding a neutralizing agent after dispersion, adding a chain extender after neutralization, distilling under reduced pressure to remove the acetone, and curing to obtain the fluorescent water-based polyurethane modified by the carbon quantum dots.

Compared with the prior art, the fluorescent water-based polyurethane modified by the carbon quantum dots is prepared from the following raw materials in parts by weight:

the preparation method of the carbon quantum dot modified fluorescent water-based polyurethane can prepare the water-based fluorescent polyurethane with multicolor luminous capacity, and has more excellent anti-counterfeiting effect. The invention innovatively uses 4,4' -dicyanomethyltrianiline and 4,4' -dialdehyde tetrastyrene derivatives as non-coplanar D-A-D ' structures, and the prepared carbon quantum dots break concentration quenching limitation, so that the quantum dot modified polyurethane has stronger luminous intensity.

The preparation method can introduce hydroxyl and amino groups on the surface of the carbon quantum dot, and particularly, polyether amine chain molecules are innovatively introduced, so that the activity of the surface amino groups and the length of chain segments are increased, the steric hindrance is reduced, the polyurethane molecules are tightly combined with the polyurethane molecules, and the stability and the color fastness of the polyurethane molecules are enhanced.

Drawings

FIG. 1 is a schematic diagram of the chemical reaction structure of the fluorescent waterborne polyurethane.

Fig. 2 is a transmission electron microscope photograph of the carbon quantum dots prepared by the present invention, and the inset is a single enlarged photograph.

FIG. 3 is a normalized fluorescence spectrum of the carbon quantum dots prepared by the invention.

FIG. 4 is a scheme showing the preparation of the aldehyde triphenylamine and derivatives thereof used in the present invention.

Fig. 5 is a schematic diagram of a reaction principle of the present invention for preparing carbon quantum dots.

FIG. 6 is a schematic flow chart of the preparation of fluorescent waterborne polyurethane.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

As shown in fig. 6, the preparation flow of the fluorescent aqueous polyurethane of the invention is as follows: placing polyisocyanate into a three-neck flask, metering polyol, hydrophilic chain extender and catalyst, uniformly dispersing, heating to 70-90 ℃, continuously stirring, and keeping for 2-4h; adding carbon quantum dots into the mixture, and reacting for 2 hours at 60-80 ℃ to obtain a prepolymer. Cooling to 5-35 ℃, adding acetone, adding water for dispersion, adding a neutralizing agent for neutralization, adding a chain extender after neutralization, distilling under reduced pressure to remove the acetone, and curing to obtain the fluorescent water-based polyurethane modified by the carbon quantum dots.

The reaction principle of the preparation steps is shown in figure 1, and the fluorescent waterborne polyurethane is mainly prepared by three parts of reaction of polyisocyanate, polyol and carbon quantum dots. The aqueous polyurethane has more hydrophilic groups, and can generate intermolecular acting forces such as hydrogen bonds, electrostatic attraction and the like with functional groups such as amino groups, carboxyl groups and the like on the surface of the carbon quantum dots, and combine the two in various modes such as chemical bonds and the like. In particular, the polyether amine terminal amino chain structure is introduced to the surface of the carbon quantum dot, so that the carbon quantum dot can be grafted into polyurethane molecules more effectively as a chain extension center. Therefore, through the chemical bonding, intermolecular acting force and space limiting effect of the carbon quantum dots and polyurethane molecules, the monodisperse carbon quantum dot aqueous polyurethane dispersion can be prepared well, as shown in fig. 2, and the aqueous polyurethane has strong solvent flushing resistance.

The fluorescent waterborne polyurethane has the fluorescence emission capability of depending on the excitation wavelength, the excitation wavelength ranges from 200 nm to 500nm, and the fluorescence emission range ranges from 300 nm to 800nm, as shown in figure 3. Along with the change of the excitation wavelength, the fluorescence emission wavelength is also changed, namely fluorescence of various colors.

The fluorescent water-based polyurethane is prepared from the following raw materials in parts by weight:

(a) 5-15 parts, preferably 6-9 parts, of polyisocyanate;

(b) 15-30 parts, preferably 18-24 parts, of a polyol;

(c) Carbon quantum dots, 0.1-0.9 parts, preferably 0.15-0.5 parts;

(d) Hydrophilic chain extender, 0.3-1.5 parts, preferably 0.5-1 part;

(e) 0.3 to 1.5 parts, preferably 0.5 to 1 part, of a neutralizing agent;

(f) 0.1 to 1 part, preferably 0.2 to 0.5 part, of a rear chain extender;

(g) 50-80 parts of water, preferably 60-70 parts.

In the present invention, the polyisocyanate is one or more selected from 2, 4-toluene diisocyanate, 2, 6-toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate and diphenylmethane diisocyanate, preferably isophorone diisocyanate.

The polyol is one or more of polyether polyol or polyester polyol, and the number average molecular weight is 1000-3000, preferably polybutylene adipate glycol with the number average molecular weight of 2000.

The hydrophilic chain extender is one or more of dimethylolpropionic acid, sodium ethylenediamine-based ethane sulfonate, ethylenediamine and methyl diethanolamine, and preferably dimethylolpropionic acid.

The neutralizing agent is triethylamine or dimethylethanolamine, preferably triethylamine.

The rear chain extender is small-molecule diamine, such as one or more of ethylenediamine, isophorone diamine and diethanolamine, preferably ethylenediamine.

In the invention, the carbon quantum dots are solid powder, the particle size is 1-20nm, and the molecular weight is 2000-10000. Specifically, the surface of the carbon quantum dot is provided with one or more of amino and hydroxyl, the amino content is 5-10wt% and the hydroxyl content is 5-15wt% calculated by mass parts.

In the invention, the carbon quantum dot is prepared from a carbon source and a doping agent. Preferably, the carbon source is a molecule of formula (I); the doping agent is as follows: ethylenediamine, polyetheramine.

Wherein the carbon source molecule is prepared from 4,4 '-dicyano methyl triphenylamine and 4,4' -dialdehyde tetraphenyl ethylene, and is shown in figure 4. Specifically, the synthesis method comprises the following steps: 1, the method comprises the following steps: 1, 4 '-dicyanomethyltrianiline and 4,4' -dialdehyde tetrastyrene are dissolved in absolute ethanol and absolute tetrahydrofuran, 0.05-0.1% sodium methoxide is rapidly added into the mixture as a base catalyst, and the mixture is heated, refluxed and stirred for 24 hours under nitrogen atmosphere. The mixture was cooled to room temperature, poured into water, extracted with methylene chloride, the solvent was removed by distillation under reduced pressure, and purified by column chromatography after drying.

The precursor 4,4' -dicyanomethyltrianiline of the carbon source molecule used in the invention is prepared from triphenylamine. The synthesis method comprises the following steps:

1) In ice bath, phosphorus oxychloride is dripped into dry N, N-dimethylformamide, and then stirred for 1-2h at room temperature. Then dripping the 1, 2-dichloroethane solution of triphenylamine into the phosphorus oxychloride/N, N-dimethylformamide system in ice bath, heating to 90 ℃, and cooling to room temperature after TLC monitoring reaction is completed. The mixture was poured into water, extracted with methylene chloride, the solvent was removed by distillation under reduced pressure and purified by column chromatography after drying to give 4,4' -dialdehydyltrianiline.

2) Slowly dropwise adding p-toluenesulfonyl methyl isonitrile into a tetrahydrofuran solution of potassium tert-butoxide under the nitrogen atmosphere at the temperature of-40 ℃, slowly dropwise adding a tetrahydrofuran solution of 4,4' -dialdehyde triphenylamine into the solution, and stirring for 45min. Then methanol was added thereto, and the mixture was heated to 80℃to react for 20 minutes. Cooling to room temperature, distilling under reduced pressure to remove the solvent, adding aqueous acetic acid solution, extracting with dichloromethane, distilling under reduced pressure to remove the solvent, drying, and purifying by column chromatography to obtain 4,4' -dicyanomethyltrianiline.

The precursor 4,4' -dialdehyde tetrastyrene of the carbon source molecule used in the present invention is prepared from tetrastyrene. The synthesis method comprises the following steps: in ice bath, phosphorus oxychloride is dripped into dry N, N-dimethylformamide, and then stirred for 1-2h at room temperature. Then dripping 1, 2-dichloroethane solution of tetraphenyl ethylene into the phosphorus oxychloride/N, N-dimethylformamide system in ice bath, heating to 90 ℃, and cooling to room temperature after TLC monitoring reaction is completed. The mixture was poured into water, extracted with methylene chloride, the solvent was removed by distillation under reduced pressure and purified by column chromatography after drying to give 4,4' -dialdehyde-tetraphenyl ethylene.

In the present invention, as shown in fig. 5, the method for preparing the carbon quantum dots is a two-step method:

1) Solid phase reaction: dissolving the prepared carbon source in anhydrous tetrahydrofuran, then rapidly adding 0.05% -0.1% sodium methoxide into the solution, uniformly dispersing the solution, and then distilling the solution under reduced pressure to remove the tetrahydrofuran; transferring the powder to a reaction kettle quickly, adding 5% -15% ethylenediamine, and placing in a200 ℃ oven for reaction for 4-12h.

2) Solvothermal reaction: dissolving the powder obtained by the solid phase reaction in tetrahydrofuran, regulating the pH to be neutral by using nitric acid, adding polyether amine into the solution, and placing the solution in a200 ℃ oven for reaction for 4-12 hours; dissolving the mixture in water, centrifuging, collecting supernatant, filtering, dialyzing, purifying, and freeze drying the dialysate to obtain carbon quantum dot powder.

Wherein the molecular weight distribution of polyetheramine used for preparing the carbon quantum dots according to the invention is 500-4000, including, but not limited to, 500, 1000, 1500, 2000, 2500, 3000, 3500, 4000.

When purifying the carbon quantum dots, the rotational speed of the centrifuge is 10000-20000 rpm, such as 10000rpm, 15000rpm, 20000rpm, etc., and the pore size of the filter membrane used for filtration is 0.2 μm. The solvent used for column chromatography purification is one or more of methanol, dichloromethane, n-hexane and toluene, and silica gel is 100-300 mesh. The molecular weight of a dialysis bag used for dialysis purification is 2000-10000, the dialysate is one or more of water, ethanol and toluene, the volume of the dialysate is 30-100 times of the volume of the dialysate to be dialyzed, and the dialysate is stirred during dialysis, and the rotating speed of a rotor is 200-800 rpm. The dialysate is replaced every 8 to 12 hours for 3 to 5 times.

The invention is further illustrated, but not limited, by the following more specific examples.

The main raw material sources used in the following examples are as follows:

the main detection method related to the embodiment is as follows:

test item	Test method
		Maximum fluorescence intensity	Agilent Cary Eclipse fluorescence spectrometer, 500nm excitation
Alcohol-resistant wiper	Color fastness tester, 75% ethanol, load 1kg, grade 3

Preparation example:

referring to fig. 4, a method for preparing a carbon source is provided, which includes the following steps:

1) 17mL of phosphorus oxychloride was added dropwise to 35mL of dry N, N-dimethylformamide in an ice bath, followed by stirring at room temperature for 1-2h. Then, 20g of 1, 2-dichloroethane solution of triphenylamine is dripped into the phosphorus oxychloride/N, N-dimethylformamide system in ice bath, the temperature is raised to 90 ℃, and the reaction is cooled to room temperature after TLC monitoring. The mixture was poured into water, extracted with methylene chloride, the solvent was removed by distillation under reduced pressure and purified by column chromatography after drying to give 4,4' -dialdehydyltrianiline.

2) 2.15g of p-toluenesulfonyl methyl isonitrile was slowly added dropwise to a tetrahydrofuran solution (50 mL) of potassium t-butoxide at a temperature of-40℃under a nitrogen atmosphere, and 17mL of a tetrahydrofuran solution containing 2.6g of 4,4' -dialdehydyltrianiline was slowly added dropwise thereto, followed by stirring for 45 minutes. Then 50mL of methanol was added thereto, and the mixture was heated to 80℃and reacted for 20min. Cooling to room temperature, distilling under reduced pressure to remove the solvent, adding 10mL of acetic acid aqueous solution, extracting with dichloromethane, distilling under reduced pressure to remove the solvent, drying, and purifying by column chromatography to obtain 4,4' -dicyanomethyltrianiline.

3) 17mL of phosphorus oxychloride was added dropwise to 35mL of dry N, N-dimethylformamide in an ice bath, followed by stirring at room temperature for 1-2h. Then 20g of 1, 2-dichloroethane solution of tetraphenyl ethylene is dripped into the phosphorus oxychloride/N, N-dimethylformamide system in ice bath, the temperature is raised to 90 ℃, and the reaction is cooled to room temperature after TLC monitoring. The mixture was poured into water, extracted with methylene chloride, the solvent was removed by distillation under reduced pressure and purified by column chromatography after drying to give 4,4' -dialdehyde-tetraphenyl ethylene.

4) 1g of 4,4 '-dicyanomethyltrianiline and 1g of 4,4' -dialdehyde tetraphenyl ethylene were dissolved in 20mL of absolute ethanol and absolute tetrahydrofuran (v: v=1: 1) To this was added 0.05g of sodium methoxide as a base catalyst rapidly, followed by stirring under reflux with heating under nitrogen atmosphere for 24 hours. The mixture was cooled to room temperature, poured into water, extracted with methylene chloride, the solvent was removed by distillation under reduced pressure, and purified by column chromatography after drying.

Example 1:

referring to fig. 1, a preparation method of fluorescent waterborne polyurethane modified by carbon quantum dots is provided, which comprises the following steps:

referring to FIG. 5, 2g of the carbon source of the preparation example was weighed into 10mL of dry tetrahydrofuran, 0.05g of sodium methoxide was rapidly added thereto, and after uniform dispersion, tetrahydrofuran was distilled off under reduced pressure. The powder was rapidly transferred to a reaction kettle, 0.2g of ethylenediamine was added, and the mixture was placed in an oven at 200℃for 8 hours.

The powder obtained by the solid phase reaction was dissolved in 10mL of tetrahydrofuran, the pH was adjusted to neutral (ph=7) using nitric acid, 0.4g PEA-D2000 was added thereto, and the mixture was placed in an oven at 200 ℃ to react for 6 hours. Dissolving the mixture in water, centrifuging to obtain supernatant, filtering, and dialyzing for purification. The dialysate was freeze-dried to give a solid powder, designated CDs1. An electron micrograph of the carbon quantum dots is shown in FIG. 2, and is 5nm spheroidal particles.

Referring again to FIG. 6, 6g of isophorone diisocyanate was placed in a three-necked flask, 18g of PBA2000,0.5g of ethylenediamine, 0.5g of 2, 2-dimethylolpropionic acid, 0.1g of organotin catalyst (the same applies hereinafter), and after uniform dispersion, the temperature was raised to 80℃and stirring was continued for 3 hours. To this was added 0.2g of CDs1 and reacted at 80℃for 2 hours. And cooling to 25 ℃, adding 10mL of acetone, adding 60mL of water for dispersion, adding 0.5g of triethylamine for neutralization after dispersion, adding 0.2g of ethylenediamine after neutralization, distilling under reduced pressure to remove the acetone, and curing to obtain the carbon quantum dot modified fluorescent water-based polyurethane. The fluorescence spectrum is shown in FIG. 3.

Comparative example 1:

the preparation method of the carbon quantum dot and the fluorescent water-based polyurethane modified by the carbon quantum dot of the conventional citric acid system is provided, and the preparation method is used as a comparative example and comprises the following steps:

1g of citric acid and 1g of urea were dissolved in 50mL of water, 0.2g of ethylenediamine was added, transferred to a polytetrafluoroethylene liner, and sealed into a reaction vessel. And (3) placing the reaction kettle in a preheated baking oven with the temperature of 200 ℃ for hydrothermal reaction for 8 hours, and taking out the reaction kettle after the reaction is finished and placing the reaction kettle at room temperature for natural cooling. After cooling, the pH was adjusted to neutral, 0.4g PEA-D2000 was added thereto, and the mixture was sealed in a reaction vessel, and the reaction was continued at 200℃for 6 hours. The reaction solution was filtered with a 0.2 μm aqueous filter under pressure, and the supernatant was centrifuged (10000 r/min,10 min). The centrifugation supernatant was taken and dialyzed in dialysis bags with mw=2000 for 24h (dialysis water was exchanged every 8h for 3 times). The solution obtained by dialysis was freeze-dried to obtain a brown powder, designated CDs2.

Referring again to FIG. 6, 6g of isophorone diisocyanate was placed in a three-necked flask, 18g of PBA2000,0.5g of ethylenediamine, 0.5g of 2, 2-dimethylolpropionic acid, 0.1g of catalyst were added, and after uniform dispersion, the temperature was raised to 80℃and stirring was continued for 3 hours. To this was added 0.2g of CDs2 and reacted at 80℃for 2 hours. And cooling to 25 ℃, adding 10mL of acetone, adding 60mL of water for dispersion, adding 0.5g of triethylamine for neutralization after dispersion, adding 0.2g of ethylenediamine after neutralization, distilling under reduced pressure to remove the acetone, and curing to obtain the carbon quantum dot modified fluorescent water-based polyurethane.

Comparative example 2:

the preparation method of the carbon quantum dot without polyether amine modification and the fluorescent water-based polyurethane modified by the carbon quantum dot is provided, and the preparation method is used as a comparative example and comprises the following steps:

Then, the powder obtained by the solid phase reaction was dissolved in 10mL of tetrahydrofuran, the pH was adjusted to neutral by using nitric acid, the mixture was dissolved in water, and the supernatant was collected by centrifugation, filtered, and purified by dialysis. The dialysate was freeze-dried to give a solid powder, designated CDs3.

Referring again to FIG. 6, 6g of isophorone diisocyanate was placed in a three-necked flask, 18g of PBA2000,0.5g of ethylenediamine, 0.5g of 2, 2-dimethylolpropionic acid, 0.1g of catalyst were added, and after uniform dispersion, the temperature was raised to 80℃and stirring was continued for 3 hours. To this was added 0.2g of CDs3 and reacted at 80℃for 2 hours. And cooling to 25 ℃, adding 10mL of acetone, adding 60mL of water for dispersion, adding 0.5g of triethylamine for neutralization after dispersion, adding 0.2g of ethylenediamine after neutralization, distilling under reduced pressure to remove the acetone, and curing to obtain the carbon quantum dot modified fluorescent water-based polyurethane.

Example 2:

the preparation method of the fluorescent water-based polyurethane modified by the excessive carbon quantum dots comprises the following steps:

referring to example 1, CDs1 were prepared.

Referring again to FIG. 6, 6g of isophorone diisocyanate was placed in a three-necked flask, 18g of PBA2000,0.5g of ethylenediamine, 0.5g of 2, 2-dimethylolpropionic acid, 0.1g of catalyst were added, and after uniform dispersion, the temperature was raised to 80℃and stirring was continued for 3 hours. To this was added 0.9g of CDs1 and the reaction was continued at 80℃for 2 hours. And cooling to 25 ℃, adding 10mL of acetone, adding 60mL of water for dispersion, adding 0.5g of triethylamine for neutralization after dispersion, adding 0.2g of ethylenediamine after neutralization, distilling under reduced pressure to remove the acetone, and curing to obtain the carbon quantum dot modified fluorescent water-based polyurethane.

Comparative example 3:

the preparation method of the fluorescent water-based polyurethane with excessive carbon quantum dots and carbon quantum dot modification of the conventional citric acid system is provided, and the preparation method is used as a comparative example and comprises the following steps:

please refer to comparative example 1 for the preparation of CDs2.

Referring again to FIG. 6, 6g of isophorone diisocyanate was placed in a three-necked flask, 18g of PBA2000,0.5g of ethylenediamine, 0.5g of 2, 2-dimethylolpropionic acid, 0.1g of catalyst were added, and after uniform dispersion, the temperature was raised to 80℃and stirring was continued for 3 hours. To this was added 0.9g of CDs2 and the reaction was continued at 80℃for 2 hours. And cooling to 25 ℃, adding 10mL of acetone, adding 60mL of water for dispersion, adding 0.5g of triethylamine for neutralization after dispersion, adding 0.2g of ethylenediamine after neutralization, distilling under reduced pressure to remove the acetone, and curing to obtain the carbon quantum dot modified fluorescent water-based polyurethane.

Example 3:

the preparation method of the fluorescent water-based polyurethane modified by the carbon quantum dots comprises the following steps:

referring to FIG. 5, 2g of the carbon source of the preparation example was weighed into 10mL of dry tetrahydrofuran, 0.05g of sodium methoxide was rapidly added thereto, and after uniform dispersion, tetrahydrofuran was distilled off under reduced pressure. The powder was rapidly transferred to a reaction kettle, 0.2g of ethylenediamine was added, and the mixture was placed in an oven at 180℃for reaction for 12 hours.

The powder obtained by the solid phase reaction was dissolved in 10mL of tetrahydrofuran, the pH was adjusted to neutrality using nitric acid, 0.2g of PEA-D500 was added thereto, and the mixture was placed in an oven at 180℃to react for 9 hours. Dissolving the mixture in water, centrifuging to obtain supernatant, filtering, and dialyzing for purification. The dialysate was freeze-dried to give a solid powder, designated CDs4.

Referring again to FIG. 6, 9g of hexamethylene diisocyanate was placed in a three-necked flask, 15g of PBA1000,0.8g of diethanolamine, 1.0g of 2, 2-dimethylolpropionic acid and 0.2g of catalyst were added, and after uniform dispersion, the temperature was raised to 70℃and stirring was continued for 3 hours. 0.1g of CDs4 was added thereto and reacted at 70℃for 3 hours. And cooling to 25 ℃, adding 15mL of acetone, adding 80mL of water for dispersion, adding 1.0g of dimethylethanolamine for neutralization after dispersion, adding 0.1g of isophorone diamine after neutralization, distilling under reduced pressure to remove acetone, and curing to obtain the carbon quantum dot modified fluorescent water-based polyurethane.

Example 4:

referring to FIG. 5, 2g of the carbon source of the preparation example was weighed into 10mL of dry tetrahydrofuran, 0.05g of sodium methoxide was rapidly added thereto, and after uniform dispersion, tetrahydrofuran was distilled off under reduced pressure. The powder was rapidly transferred to a reaction kettle, 0.2g of ethylenediamine was added, and the mixture was placed in an oven at 240℃for 4 hours.

The powder obtained by the solid phase reaction was dissolved in 10mL of tetrahydrofuran, the pH was adjusted to neutrality using nitric acid, 0.8g of PEA-D4000 was added thereto, and the mixture was placed in an oven at 240℃to react for 3 hours. Dissolving the mixture in water, centrifuging to obtain supernatant, filtering, and dialyzing for purification. The dialysate was freeze-dried to give a solid powder, designated CDs5.

Referring again to FIG. 6, 8g of diphenylmethane diisocyanate was placed in a three-necked flask, 20g of PBA3000,0.8g of ethylenediamine, 1.2g of 2, 2-dimethylolpropionic acid, 0.15g of catalyst were added, and after uniform dispersion, the temperature was raised to 90℃and stirring was continued, and the mixture was maintained for 2 hours. To this was added 0.5g of CDs5 and the reaction was continued at 90℃for 2 hours. Cooling to 25 ℃, adding 12mL of acetone, adding 70mL of water for dispersion, adding 0.3g of dimethylethanolamine for neutralization after dispersion, adding 0.8g of diethanolamine after neutralization, distilling under reduced pressure to remove the acetone, and curing to obtain the carbon quantum dot modified fluorescent water-based polyurethane.

Example 5:

referring to example 1, CDs1 were prepared.

Referring again to FIG. 6, 15g of isophorone diisocyanate was placed in a three-necked flask, 30g of PBA2000,1.0g of ethylenediamine, 1.5g of 2, 2-dimethylolpropionic acid, and 0.2g of catalyst were added, and after uniform dispersion, the temperature was raised to 80℃and stirring was continued for 3 hours. To this was added 0.2g of CDs1 and reacted at 80℃for 2 hours. And cooling to 25 ℃, adding 15mL of acetone, adding 80mL of water for dispersion, adding 1.5g of dimethylethanolamine for neutralization after dispersion, adding 0.8g of isophorone diamine after neutralization, distilling under reduced pressure to remove the acetone, and curing to obtain the carbon quantum dot modified fluorescent water-based polyurethane.

Example 6:

referring to example 3, CDs4 was prepared.

Referring again to FIG. 6, 5g toluene diisocyanate was placed in a three-necked flask, 16g PBA2000,0.1g ethylenediamine, 0.4g2, 2-dimethylolpropionic acid, 0.05g catalyst were added, and after uniform dispersion, the temperature was raised to 70℃and stirring was continued for 3 hours. 0.1g of CDs4 was added thereto and reacted at 70℃for 3 hours. Cooling to 25 ℃, adding 5mL of acetone, adding 50mL of water for dispersion, adding 0.3g of triethylamine for neutralization after dispersion, adding 0.5g of ethylenediamine after neutralization, distilling under reduced pressure to remove acetone, and curing to obtain the carbon quantum dot modified fluorescent water-based polyurethane.

Example 7:

referring to example 4, CDs5 was prepared.

Referring again to FIG. 6, 5g isophorone diisocyanate was placed in a three-necked flask, 15g PBA2000,0.15g ethylenediamine, 0.3g2, 2-dimethylolpropionic acid, 0.05g catalyst were added, and after uniform dispersion, the temperature was raised to 90℃and stirring was continued for 2 hours. To this was added 0.5g of CDs5 and the reaction was continued at 90℃for 2 hours. Cooling to 25 ℃, adding 5mL of acetone, adding 50mL of water for dispersion, adding 1.5g of triethylamine for neutralization after dispersion, adding 0.5g of diethanolamine after neutralization, distilling under reduced pressure to remove the acetone, and curing to obtain the carbon quantum dot modified fluorescent water-based polyurethane.

The results of the performance test of the carbon quantum dot modified fluorescent water-based polyurethane obtained in the examples and the comparative examples are as follows:

comparison of example 1 with comparative example 1 shows that: compared with the fluorescent water-based polyurethane prepared by a conventional carbon source, the fluorescent water-based polyurethane modified by the carbon quantum dots has more excellent fluorescence intensity and alcohol rub fastness. Comparison of example 1 with comparative example 2 shows that: the polyether amine structure introduced on the surface of the carbon quantum dot can effectively increase the alcohol rub fastness. Comparison of example 2 with comparative example 3 shows that: the carbon quantum dot designed by the invention can still maintain higher fluorescence intensity and better alcohol rub fastness when excessive, and the fluorescence intensity and alcohol rub fastness of the quantum dot prepared by the conventional carbon source are greatly weakened when excessive.

The above embodiments are provided to illustrate the technical concept and features of the present invention and are intended to enable those skilled in the art to understand the content of the present invention and implement the same, and are not intended to limit the scope of the present invention. All equivalent changes or modifications made in accordance with the spirit of the present invention should be construed to be included in the scope of the present invention.

Claims

1. The fluorescent water-based polyurethane modified by the carbon quantum dots is characterized by being prepared from the following raw materials:

(a) A polyisocyanate;

(b) A polyol;

(c) Carbon quantum dots;

(d) Hydrophilic chain extenders;

(e) A neutralizing agent;

(f) A rear chain extender;

(g) And (3) water.

2. The fluorescent waterborne polyurethane of claim 1, wherein the fluorescent waterborne polyurethane is prepared from the following raw materials in parts by weight:

(a) 5-15 parts, preferably 6-9 parts, of polyisocyanate;

(b) 15-30 parts, preferably 18-24 parts, of a polyol;

(c) 0.1 to 0.9 part, preferably 0.15 to 0.5 part, of carbon quantum dots;

(d) 0.3 to 1.5 parts, preferably 0.5 to 1 part, of hydrophilic chain extender;

(e) 0.3 to 1.5 parts, preferably 0.5 to 1 part, of neutralizing agent;

(f) 0.1 to 1 part, preferably 0.2 to 0.5 part, of a rear chain extender;

(g) 50-80 parts of water, preferably 60-70 parts.

3. The fluorescent waterborne polyurethane according to claim 1 or 2, wherein the carbon quantum dots are solid powder, the particle size is 1-20nm, and the number average molecular weight is 2000-10000.

4. The fluorescent waterborne polyurethane according to any one of claims 1-3, wherein the carbon quantum dots are prepared from a carbon source, ethylenediamine and polyetheramine, wherein the carbon source accounts for 70-90% by mass, the ethylenediamine accounts for 5-20% by mass and the polyetheramine accounts for 5-10% by mass.

5. The fluorescent waterborne polyurethane according to any one of claims 1-4, wherein the carbon source structure is shown in formula (I); preferably, the carbon source is prepared by reacting 4,4 '-dicyano methyl triphenylamine with 4,4' -dialdehyde tetraphenyl ethylene or a derivative thereof.

6. Fluorescent aqueous polyurethane according to any one of claims 1 to 5, characterized in that the polyetheramine has a molecular weight of 500 to 4000, preferably 600 to 1000.

7. The fluorescent waterborne polyurethane according to any one of claims 1-6, wherein the preparation method of the carbon quantum dots comprises the following steps:

8. The fluorescent waterborne polyurethane according to claim 7, wherein the rotational speed of the centrifuge in the step 3) is 10000-20000 rpm, and the pore diameter of a filter membrane used for filtering is 0.2 μm; preferably, the solvent used for column chromatography purification is one or more of methanol, dichloromethane, n-hexane and toluene, and silica gel is 100-300 meshes; the molecular weight of a dialysis bag used for dialysis and purification is 2000-10000, and the dialyzate is one or more of water, ethanol and toluene; preferably, the volume of the dialysate is 30-100 times that of the dialysate to be dialyzed, and stirring is carried out during dialysis, and the rotating speed of the rotor is 200-800 rpm; more preferably, the dialysate is replaced every 8 to 12 hours, 3 to 5 times in total.

9. The fluorescent waterborne polyurethane according to any one of claims 1-8, wherein the fluorescent waterborne polyurethane can emit light in a solid state into fluorescent light with various colors, has fluorescence emission capability depending on excitation wavelength, and has an excitation wavelength range of 200-500nm and a fluorescence emission range of 300-800nm.

10. The method for preparing fluorescent waterborne polyurethane according to any one of claims 1 to 9, comprising the following steps: