阅读说明：本技术 一种量子点-超支化聚合物复合物的制备方法 (Preparation method of quantum dot-hyperbranched polymer compound ) 是由 朱新远 童刚生 孙佩 李竞 于 2021-06-30 设计创作，主要内容包括：本发明公开了一种量子点-超支化聚合物复合物的制备方法,包括步骤：制备骨架内带有巯基官能团的超支化聚甲基丙烯酸甲酯；将上述超支化聚合物与量子点共同分散到良溶剂中充分搅拌吸附,得到混合液；将上述混合液加入不良溶剂中沉淀,得到量子点-超支化聚合物复合物。本发明利用骨架内带有巯基官能团的超支化聚甲基丙烯酸甲酯为稳定剂,首先通过巯基将量子点吸附到超支化聚合物的空腔中,再利用周围的致密的聚甲基丙烯酸酯进一步包裹量子点,阻隔外界水氧对量子点的侵蚀。该方法显著减缓了量子点的光漂白速率,大幅提高了量子点制品的稳定性。(The invention discloses a preparation method of a quantum dot-hyperbranched polymer compound, which comprises the following steps: preparing hyperbranched polymethyl methacrylate with a mercapto functional group in a framework; dispersing the hyperbranched polymer and the quantum dots into a good solvent together, and fully stirring and adsorbing to obtain a mixed solution; and adding the mixed solution into a poor solvent for precipitation to obtain the quantum dot-hyperbranched polymer compound. The hyperbranched polymethyl methacrylate with the mercapto functional group in the skeleton is used as a stabilizer, the quantum dots are firstly adsorbed into the cavity of the hyperbranched polymer through mercapto groups, and then the quantum dots are further wrapped by the surrounding dense polymethacrylate, so that the corrosion of external water and oxygen to the quantum dots is prevented. The method obviously slows down the photobleaching rate of the quantum dots, and greatly improves the stability of quantum dot products.)

1. The hyperbranched polymethyl methacrylate is characterized in that a reactive chain transfer agent with trithio ester functional groups and methacrylic acid ester are used as precursors, RAFT polymerization is carried out in the presence of an initiator, and a polymerization product is aminolyzed to prepare the hyperbranched polymethyl methacrylate.

2. The hyperbranched polymethylmethacrylate according to claim 1, wherein the reactive chain transfer agent is a bifunctional monomer having a double bond at one end of the molecular structure and a trithioester functional group at the other end.

3. The hyperbranched polymethylmethacrylate according to claim 1, wherein the initiator comprises at least one of an organic peroxide and an azo-based initiator.

4. The hyperbranched polymethylmethacrylate according to claim 1, wherein the reactive transfer agent, the methacrylate and the initiator are present in a molar ratio of 1: 100: 0.5-1: 10: 0.05.

5. the hyperbranched polymethyl methacrylate is characterized by having the following structural formula:

6. a method for preparing a quantum dot-hyperbranched polymer composite, the method comprising the steps of:

s1, dispersing the hyperbranched polymethyl methacrylate of claim 1 or the hyperbranched polymethyl methacrylate of claim 5 and quantum dots into a good solvent together, and fully stirring and adsorbing to obtain a mixed solution;

and S2, adding the mixed solution into a poor solvent for precipitation to obtain the quantum dot-hyperbranched polymer compound.

7. The preparation method of the quantum dot-hyperbranched polymer compound as claimed in claim 6, wherein the quantum dot comprises one or more of cadmium selenide, indium phosphide and perovskite quantum dots, and a core-shell structure or doped quantum dot formed by taking one or more of cadmium selenide, indium phosphide and perovskite quantum dots as a core through multiple coatings.

8. The preparation method of the quantum dot-hyperbranched polymer composite according to claim 6, wherein the mass ratio of the hyperbranched polymethylmethacrylate to the quantum dot is 500: 1-50: 1.

9. the method of claim 6, wherein the good solvent is toluene or chloroform; the poor solvent is one or a mixture of methanol, ethanol, acetone and acetonitrile.

10. The application of the quantum dot-hyperbranched polymer composite prepared by the method of claim 6 in preparing quantum dot products, wherein the quantum dot-hyperbranched polymer composite is added into plastic particles, curing glue or printing ink to prepare quantum dot products.

Technical Field

The application belongs to the field of nano materials, and relates to a preparation method of a quantum dot-hyperbranched polymer compound.

Background

Quantum dots are nano-scale crystalline materials that can efficiently emit light of a particular frequency under an applied electric field or illumination. Therefore, quantum dots have a very wide application prospect in the display field as luminescent materials.

However, as is well known, although quantum dots are inorganic materials, their stability is not as high as the stability of OLED, and their light-emitting performance is still very susceptible to the external environment, and the conditions of moisture, oxygen, high temperature and light all cause the stability of quantum dots to be poor and the optical performance to be degraded. The unstable luminescent property will greatly affect the practicability of quantum dot products, and greatly hinder the large-scale commercial application of quantum dots. Therefore, the improvement of the stability of the quantum dots is an urgent need of downstream application manufacturers of the quantum dots.

By searching the existing patent literature, CN202011014347 discloses a perovskite quantum dot invisible ink-jet printing ink, which is modified by wrapping quantum dots in polymethyl methacrylate by an in-situ polymerization method. On one hand, the in-situ polymerization wrapping method can damage the luminescence property of the quantum dots to a certain extent at the polymerization temperature (50-70 ℃) and the benzoyl peroxide serving as an initiator in the polymerization process; on the other hand, in order to enable the polymethyl methacrylate/perovskite quantum dot composite to be naturally precipitated from a polymerization system, n-hexane is used as a solvent when the polymethyl methacrylate is synthesized, but the n-hexane is known to be a poor solvent of the polymethyl methacrylate, so that the polymethyl methacrylate precipitated in the n-hexane is expected to have low molecular weight and difficult to play a good protection role on the perovskite quantum dots wrapped in the n-hexane.

CN201910986871 discloses a quantum dot light diffusing agent and a preparation method thereof, wherein the quantum dot light diffusing agent is prepared by wrapping cadmium selenide quantum dots with acrylic acid modified polymethyl methacrylate, and the stability of the quantum dots can be improved while the obtained polymethyl methacrylate quantum dot microspheres are used as the light diffusing agent. However, it has the following disadvantages: 1. the acrylic acid modified polymethyl methacrylate can form hollow micelles in water after the pH is adjusted to be alkaline; and then adding the quantum dots dispersed in solvents such as n-hexane and the like into the hollow micelle solution, and finally adjusting the pH value to be alkaline to promote the polymer to precipitate from water, thereby obtaining the quantum dot-polymethyl methacrylate microspheres. It does not explain how quantum dots enter the interior of hollow micelles without any driving force; therefore, in combination with the common knowledge in the art, the quantum dots precipitated from the polymethyl methacrylate microspheres may not be effectively wrapped in the microspheres, but rather may be attached to the surfaces of the microspheres. Therefore, the footing point of coating the quantum dots with polymethyl methacrylate to improve the stability of the quantum dots is lost. 2. According to the description, the quantum dots entering the interior of the microsphere are also in a tightly aggregated state with each other, provided that the quantum dots can effectively enter the interior of the polymethyl methacrylate hollow micelle. According to literature reports, when quantum dots are tightly aggregated, self-absorption effect exists, and the luminous efficiency of the quantum dots is greatly reduced.

In order to solve the technical problems, the invention provides a preparation method of a quantum dot-hyperbranched polymer compound. The hyperbranched polymethyl methacrylate with sulfydryl in the framework is prepared, and is directly blended with quantum dots, firstly, the quantum dots are dispersed and adsorbed in a cavity of the hyperbranched polymer through the sulfydryl distributed in the hyperbranched polymer framework, so that the reduction of the luminous performance caused by the aggregation of the quantum dots is avoided; and then, the quantum dots are further wrapped and protected by using the surrounding compact polymethyl methacrylate, so that the corrosion of external water and oxygen to the quantum dots is prevented, and the stability of the quantum dots is improved. The method can obviously slow down the photobleaching rate of the quantum dots and greatly improve the stability of the quantum dots.

Disclosure of Invention

The invention aims to provide a preparation method of a quantum dot-hyperbranched polymer compound aiming at the problems that quantum dots are quickly photobleached and the luminous performance is greatly reduced under illumination; the prepared hyperbranched polymer coated quantum dot has excellent light stability.

In order to solve the problems, the invention provides hyperbranched polymethyl methacrylate which is prepared by taking a reactive chain transfer agent with trithioester functional groups and methacrylic acid ester as precursors, carrying out RAFT polymerization in the presence of an initiator and carrying out aminolysis on a polymerization product. The aminolysis is aminolysis of trithioester in the polymerization product to sulfhydryl. The hyperbranched polymethyl methacrylate skeleton is internally provided with a mercapto functional group.

As an embodiment of the invention, the invention provides hyperbranched polymethyl methacrylate which is prepared by taking a reactive chain transfer agent with trithio ester functional groups and methacrylate as precursors, carrying out RAFT polymerization in the presence of an initiator and carrying out aminolysis on a polymerization product.

As an embodiment of the invention, the RAFT polymerisation is specifically:

mixing the reactive chain transfer agent with trithio ester functional group, methacrylate, initiator and solvent, sealing, performing freeze-thaw cycle for several times, heating to room temperature, and reacting in oil bath at 70-80 deg.C for 22-26 hr. The solvent is selected from one or more of 1,4-dioxane and dimethyl sulfoxide.

After the reaction is finished, putting the mixture into ice water to terminate the reaction, then precipitating the mixture by using anhydrous ether, dissolving the solid obtained by centrifugation into dichloromethane, then repeatedly precipitating the mixture in ether for a plurality of times, and drying the mixture to obtain light yellow powder, namely a polymerization product, namely the hyperbranched polymethyl methacrylate.

As an embodiment of the present invention, the aminolysis comprises the steps of: dissolving hyperbranched polymethyl methacrylate in a solvent under the protection of argon, dropwise adding n-hexylamine, stirring at room temperature, and bubbling for 20-40 minutes; after the reaction is finished, the mixed solution is dripped into ether for precipitation to obtain white solid, namely the hyperbranched polymethyl methacrylate with the mercapto functional group. The addition amount of n-hexylamine is 2.5-3.5ml/50mmol relative to the hyperbranched polymethyl methacrylate. The solvent comprises one of tetrahydrofuran or dichloromethane.

As an embodiment of the present invention, the reactive chain transfer agent is a bifunctional monomer having a molecular structure with a double bond at one end and a trithioester functional group at the other end.

As an embodiment of the present invention, the initiator includes at least one of an organic peroxide and an azo-type initiator.

As an embodiment of the present invention, the molar ratio of the reactive chain transfer agent, methacrylate, and initiator is 1: 100: 0.5-1: 10: 0.05.

the invention also provides hyperbranched polymethyl methacrylate, which has the following structural formula:

in the structural formula, parentheses represent repeating units; the number of the repeating units is in the range of 5 to 30.

The invention also provides a preparation method of the quantum dot-hyperbranched polymer compound, which comprises the following steps:

s1, dispersing the hyperbranched polymethyl methacrylate or the hyperbranched polymethyl methacrylate and the quantum dots into a good solvent together, and fully stirring and adsorbing to obtain a mixed solution;

and S2, adding the mixed solution into a poor solvent for precipitation to obtain the quantum dot-hyperbranched polymer compound.

As an embodiment of the invention, the quantum dots comprise one or more of cadmium selenide, indium phosphide and perovskite quantum dots, and core-shell structures or doped quantum dots formed by taking one or more of cadmium selenide, indium phosphide and perovskite quantum dots as cores and through various coatings.

According to one embodiment of the invention, the mass ratio of the hyperbranched polymethyl methacrylate or the hyperbranched polymethyl methacrylate to the quantum dots is 500: 1-50: 1.

as an embodiment of the present invention, the good solvent is toluene or chloroform.

As an embodiment of the present invention, the poor solvent is one or more of methanol, ethanol, acetone, and acetonitrile.

The invention also provides application of the quantum dot-hyperbranched polymer composite prepared by the method in preparation of quantum dot products.

As an embodiment of the present invention, the quantum dot-hyperbranched polymer composite is added to plastic particles, curing glue or printing ink to form a quantum dot product.

The invention provides a preparation method of a quantum dot-hyperbranched polymer compound, aiming at the problem that quantum dots rapidly lose effectiveness under illumination. Compared with the prior art, the invention has the following beneficial effects:

1. the quantum dots are coated by the functionalized hyperbranched polymer, firstly, the functionalized hyperbranched polymer is firmly adsorbed into a cavity of the hyperbranched polymer through the coordination of sulfydryl in a framework and metal on the surface of the quantum dots, and then the quantum dots are further coated by a compact polymethyl methacrylate layer in the hyperbranched polymer framework to prevent the corrosion of external water and oxygen to the quantum dots; compared with the existing micromolecule or linear polymer coating technology, the hyperbranched polymer has a wide internal cavity and a compact spherical structure, and can provide more effective protection for quantum dots.

2. Compared with the quantum dots which are not coated, the quantum dots coated with the hyperbranched polymer prepared by the invention can effectively prevent the erosion of moisture and oxygen to the quantum dots, and obviously improve the light stability of the quantum dots.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

fig. 1 is a schematic flow chart of a method for preparing a quantum dot-hyperbranched polymer composite according to an embodiment of the present invention;

FIG. 2 is the chemical structure of a hyperbranched polymer prepared in example 1 of the present invention;

FIG. 3 is an IR spectrum of a hyperbranched polymer prepared in example 1 of the invention;

FIG. 4 is a comparison of brightness data for two panels prepared according to example 3 of the present invention after aging for different periods of time.

FIG. 5 is a comparison of brightness data for two sheets prepared according to comparative example 1 of the present invention aged for different times.

FIG. 6 is a comparison of brightness data for two panels made according to comparative example 2 of the present invention aged for different times.

Detailed Description

The present invention will be described in detail with reference to examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be apparent to those skilled in the art that several modifications and improvements can be made without departing from the inventive concept. All falling within the scope of the present invention.

Example 1

The preparation route of the hyperbranched polymethyl methacrylate with sulfydryl in the framework is shown in figure 2:

monomer type chain transfer agent S-p-vinylphenyl S' -propyl trithiocarbonate (640mg,2.4mmol), methyl methacrylate monomer MMA (5g,50mmol) and initiator azobisisobutyronitrile AIBN (40mg,0.24mmol) are added into a reaction bottle, then 30mL of mixed solvent of 1,4-dioxane (1, 4-dioxane)/DMSO (dimethyl sulfoxide) (l: l, v/v) is added, then the reaction bottle is sealed, after three freeze-thaw cycles, the reaction bottle is put into an oil bath at 75 ℃ to react for 24 hours after being heated to room temperature. After the reaction is finished, immediately putting the reaction bottle into ice water to terminate the reaction, dropwise adding the mixed solution into a large amount of anhydrous ether to precipitate, dissolving the solid obtained by centrifugation into dichloromethane, repeatedly precipitating in ether for three times, and drying to obtain light yellow powder.

Dissolving the light yellow powder into 20 ml of tetrahydrofuran under the protection of argon, dropwise adding 3 ml of n-hexylamine by using a syringe, stirring and bubbling at room temperature for 30 minutes, and aminolyzing trithioester in the hyperbranched polymethyl methacrylate into sulfydryl. After the reaction is finished, dropwise adding the mixed liquid into ether for precipitation to obtain a white solid, namely hyperbranched polymethyl methacrylate with sulfydryl in the framework; the IR spectrum of the polymer is shown in FIG. 3.

Example 2

Preparation of quantum dot-hyperbranched polymer composite:

as shown in fig. 1, 2 g of the prepared hyperbranched polymer was dissolved in chloroform, then a quantum dot solution (0.25 ml, solid content 10%, green cadmium selenide alloy quantum dots) dispersed in chloroform was added dropwise to the hyperbranched polymer solution, and the mixture was sealed and stirred at room temperature for 2 hours to ensure that the quantum dots were completely adsorbed into the hyperbranched polymer cavity under the action of thiol groups.

And then, dropwise adding the mixed solution into ethanol for precipitation, drying the solid and grinding the solid into powder to obtain the quantum dot-hyperbranched polymer compound.

Example 3

Testing the light stability of the quantum dot-hyperbranched polymer composite:

100 g of polystyrene plastic particles and 0.2 g of quantum dot-hyperbranched polymer composite powder are fully and uniformly mixed, the obtained mixed material is added into a miniature double-screw extruder, the extrusion temperature is set to 210 ℃, the rotating speed of a feeding machine is 30 revolutions per minute, the rotating speed of the extruder is 40 revolutions per minute, after an extruded strip is cooled, the extruded strip is pressed into a quantum dot sheet with the thickness of 1mm by a flat vulcanizing machine, and the quantum dot sheet is taken as an experimental group and marked as a hyperbranched polymer coated quantum dot sheet.

After stirring and mixing 100 g of polystyrene and 0.1 g of quantum dot powder uniformly, preparing a quantum dot sheet without hyperbranched polymer coating in the same manner, and taking the quantum dot sheet as a blank control group and marking as an uncoated quantum dot sheet.

Placing the two groups of plates under a blue light LED lamp for irradiation and aging, wherein the wavelength of a light source is 400nm, and the power is 120W/m². And (3) carrying out tracking test on the brightness value of the quantum dot sheet by using a color analyzer at different irradiation times, and comparing the light stability of the experimental group with that of the blank group.

The aging data is shown in fig. 4, and after the hyperbranched polymer is used for coating, the light stability of the quantum dots in polystyrene is greatly improved.

Comparative example 1

Preparation of the thiol-free hyperbranched polymethyl methacrylate-quantum dot complex:

the experimental procedure is as in example 2, except that the selected hyperbranched polymer was replaced with the hyperbranched polymethylmethacrylate prepared in example 1 without aminolysis. The obtained product is marked as a sulfydryl-free hyperbranched polymethyl methacrylate-quantum dot compound.

Stability testing of thiol-free hyperbranched polymethylmethacrylate-quantum dot complexes:

100 g of polystyrene plastic particles and 0.2 g of thiol-free hyperbranched polymethyl methacrylate-quantum dot composite powder are fully and uniformly mixed, the obtained mixed material is added into a miniature double-screw extruder, the extrusion temperature is set to 210 ℃, the rotating speed of the feeding machine is 30 revolutions per minute, the rotating speed of the extruder is 40 revolutions per minute, after the extruded strips are cooled, the extruded strips are pressed into quantum dot sheets with the thickness of 1mm by a flat-plate vulcanizing machine, and the quantum dot sheets are used as experimental groups and marked as thiol-free hyperbranched polymethyl methacrylate coated quantum dot sheets.

After stirring and mixing 100 g of polystyrene and 0.1 g of quantum dot powder uniformly, preparing a quantum dot sheet without hyperbranched polymer coating in the same manner, and taking the quantum dot sheet as a blank control group and marking as an uncoated quantum dot sheet.

Placing the two groups of plates under a blue light LED lamp for irradiation and aging, wherein the wavelength of a light source is 400nm, and the power is 120W/m². And (3) carrying out tracking test on the brightness value of the quantum dot sheet by using a color analyzer at different irradiation times, and comparing the light stability of the experimental group with that of the blank group.

The aging data is shown in fig. 5, after the quantum dots are coated by the thiol-free hyperbranched polymethylmethacrylate, the light stability of the quantum dots in polystyrene is greatly improved by a smaller range than that of the quantum dots coated by the thiol-containing hyperbranched polymethylmethacrylate. This is mainly because, in the absence of thiol groups, quantum dots cannot be effectively adsorbed into the hyperbranched polymer, and most of the quantum dots are adsorbed on the surface of the hyperbranched polymer, so that most of the quantum dots cannot be effectively coated with polymethyl methacrylate.

Comparative example 2

Preparing a hyperbranched polyvinyl amide-quantum dot compound:

the experimental procedure is the same as in example 2, except that the selected hyperbranched polymer is hyperbranched polyvinylamide. The obtained product is marked as a hyperbranched polyvinyl amide-quantum dot compound.

Testing the stability of the hyperbranched polyvinyl amide-quantum dot complex:

100 g of polystyrene plastic particles and 0.2 g of hyperbranched polyvinyl amide-quantum dot composite powder are fully and uniformly mixed, the obtained mixed material is added into a miniature double-screw extruder, the extrusion temperature is set to 210 ℃, the rotating speed of a feeding machine is 30 revolutions per minute, the rotating speed of the extruder is 40 revolutions per minute, after extruded strips are cooled, the extruded strips are pressed into quantum dot sheets with the thickness of 1mm by a flat plate vulcanizing machine, and the quantum dot sheets are used as an experimental group and marked as hyperbranched polyvinyl amide coated quantum dot sheets.

After stirring and mixing 100 g of polystyrene and 0.1 g of quantum dot powder uniformly, preparing a quantum dot sheet without hyperbranched polymer coating in the same manner, and taking the quantum dot sheet as a blank control group and marking as an uncoated quantum dot sheet.

Placing the two groups of plates under a blue light LED lamp for irradiation and aging, wherein the wavelength of a light source is 400nm, and the power is 120W/m². And (3) carrying out tracking test on the brightness value of the quantum dot sheet by using a color analyzer at different irradiation times, and comparing the light stability of the experimental group with that of the blank group.

The aging data is shown in fig. 6, and after the coating with hyperbranched polyvinyl amide, the photostability of the quantum dots in polystyrene is not improved. This is mainly because the hyperbranched polyvinylamide cannot effectively block water and oxygen from approaching the quantum dots, and thus cannot effectively protect the quantum dots and improve the stability thereof.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention.