Random copolymer containing maleic anhydride, preparation method of random copolymer and application of random copolymer in quantum dot packaging glue
By preparing random copolymers containing maleic anhydride wrapped quantum dots, the interfacial compatibility and agglomeration problems in quantum dot optical films are solved, and the luminescence efficiency and stability are improved, making them suitable for industrial production.
Patent Information
- Application Number
- CN202510634253.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-16
- Publication Date
- 2025-07-22
AI Technical Summary
In quantum dot optical films, the difference in polarity between the surface ligands of quantum dots and polymers leads to poor interfacial compatibility, quantum dots are prone to agglomeration, affecting luminescence intensity and uniformity, and photochemical reactions or thermal curing may quench the quantum dots and reduce brightness.
Random copolymers containing maleic anhydride are prepared by RAFT polymerization method, and the interaction between maleic anhydride and the surface of quantum dots is used to wrap, improve interface binding, reduce agglomeration, and quantum dot encapsulation glue is prepared by crosslinking agents and photoinitiators.
It improves the luminous efficiency and stability of quantum dots, reduces the agglomeration and bright spots of red and green dots, enhances the stability and life of the quantum dot optical film, and is suitable for large-scale industrial production.
Smart Images
Figure CN120349453A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of quantum dot encapsulation materials, and particularly relates to a random copolymer containing maleic anhydride, a preparation method thereof, and an application thereof in quantum dot encapsulation glue. Background Art
[0002] In the process of manufacturing quantum dot optical films, the stability of quantum dot surface ligands and the interfacial compatibility with polymer types and solvents are key issues to be solved. Quantum dot ligands and common polymers usually have large polarity differences. Currently, the concentration of quantum dots in quantum dot optical films needs to be high enough to achieve the absorption of background blue light and convert it into red and green light. Therefore, the concentration of quantum dots in the glue is usually very large and prone to aggregation, which affects the luminescence intensity and luminescence uniformity. In addition, free radicals generated by photochemical reactions or thermal curing during the curing process of quantum dot optical films may quench the quantum dots and reduce the brightness of the quantum dot films.
[0003] Therefore, it is necessary to develop a suitable quantum dot-ligand-polymer system to improve the surface coverage rate of quantum dots (repair defects on the surface of quantum dots), improve the solubility of quantum dots in polymer monomers, avoid aggregation between red and green quantum dots, improve the barrier ability of quantum dots to external water and oxygen, and increase their service life in devices. Summary of the Invention
[0004] Technical problems to be solved: Aiming at the above technical problems, the present invention provides a random copolymer containing maleic anhydride, a preparation method thereof, and an application thereof in quantum dot encapsulation glue, which can improve the luminous efficiency of quantum dots, improve the interfacial bonding problem between quantum dots and the glue matrix, increase the compatibility of quantum dots with the glue monomer mixture, and reduce the aggregation and bright spot phenomena of red dots and green dots in the quantum dot optical film; at the same time, the preparation method has a short process, simple operation, mild conditions, and is convenient for large-scale industrial coating production.
[0005] Technical solution: A preparation method of a random copolymer containing maleic anhydride, the steps are as follows: Step 1. Disperse acrylate monomers and maleic anhydride in a solvent, and then add a RAFT reagent and an initiator; Step 2. Heat and polymerize under an inert atmosphere to obtain a polymerization product; Step 3. Dissolve the polymerization product, precipitate with a precipitating agent, and dry to obtain the random copolymer containing maleic anhydride.
[0006] Preferably, the acrylate monomer is: n-butyl acrylate, methyl acrylate, tert-butyl acrylate, ethyl acrylate or isobornyl acrylate.
[0007] Preferably, the solvent is: toluene, 1,4-dioxane, tetrahydrofuran or N,N-dimethylformamide.
[0008] Preferably, the RAFT reagent is: 2-(dodecylthio carbonothioylthio)-2-methylpropanoic acid, diisopropylxanthogen disulfide, 4-cyano-4-(phenylthiocarbonothioylthio)pentanoic acid or ethylxanthic acid.
[0009] Preferably, the initiator is: azobisisobutyronitrile, benzoyl peroxide, di-tert-butyl peroxide or dimethyl 2,2'-azobis(2-methylpropionate).
[0010] Preferably, the precipitant is: methanol, ethanol, petroleum ether or n-hexane.
[0011] Preferably, the molar ratio of the RAFT reagent, acrylate monomer, maleic anhydride and initiator is 1:(100 - 10000):(5 - 200):(0.1 - 0.3).
[0012] Preferably, the mass ratio of the acrylate monomer and the solvent is 1:(10 - 50).
[0013] Preferably, the temperature of the heating reaction is 50 - 80 °C and the time is 12 - 24 h.
[0014] Preferably, the temperature of the drying is 40 - 70 °C and the time is 12 - 36 h.
[0015] The random copolymer containing maleic anhydride prepared by the above method.
[0016] Preferably, the number-average relative molecular weight of the random copolymer containing maleic anhydride is 500 - 100000 g / mol, and the content of maleic anhydride is 10 - 20 wt%.
[0017] The application of the above random copolymer containing maleic anhydride in the preparation of quantum dot encapsulating glue, and the specific preparation method is as follows: dissolving the random copolymer containing maleic anhydride in an active solvent, and then adding a crosslinking agent and a photoinitiator and stirring to obtain the quantum dot encapsulating glue.
[0018] Preferably, the active solvent is ethyl acrylate or isobornyl acrylate.
[0019] Preferably, the mass ratio of the active solvent and the random copolymer containing maleic anhydride is 80:20 - 30:70.
[0020] Preferably, the crosslinking agent is selected from one or more of pentaerythritol triacrylate, neopentyl glycol diacrylate, pentaerythritol tetraacrylate, diethylene glycol diacrylate and dipentaerythritol hexaacrylate.
[0021] Preferably, the crosslinking agent accounts for 1% - 10% of the total mass of the random copolymer containing maleic anhydride and the active solvent.
[0022] Preferably, the photoinitiator is acetophenone, benzophenone or benzoin dimethyl ether.
[0023] Preferably, the photoinitiator accounts for 0.5% - 5% of the total mass of the random copolymer containing maleic anhydride and the active solvent.
[0024] The quantum dot encapsulating glue prepared by the above application.
[0025] Preferably, in the quantum dot encapsulating glue, by mass, it includes the following components: a total of 100 parts of the random copolymer containing maleic anhydride and the active solvent, 1 - 10 parts of the crosslinking agent, 0.5 - 5 parts of the photoinitiator, wherein the mass ratio of the active solvent to the random copolymer containing maleic anhydride is 80:20 - 30:70.
[0026] The application of the above quantum dot encapsulating glue in the photocuring encapsulation of quantum dots.
[0027] Preferably, when the quantum dot encapsulating glue is used for the photocuring encapsulation of quantum dots, the quantum dots account for 2% - 10% of the mass of the glue.
[0028] Beneficial effects: In the present invention, the interaction between the characteristic functional groups of maleic anhydride in the random copolymer and the functional groups or defect sites (hanging bonds) on the surface of the quantum dots is utilized for coordination to wrap the quantum dots in the "three - dimensional space", passivating the defect sites on the surface of the quantum dots and improving the luminescence yield of the quantum dots; after the random copolymer modifies the quantum dots, the quantum dots have better dispersibility, and the prepared glue can make nano - scale red and green quantum dots uniformly dispersed in the glue, reducing the agglomeration phenomenon (red dots, green dots, bright spots, etc.) after the quantum dot encapsulating glue forms a film; by means of the encapsulation of the quantum dots by the random copolymer, the contact between the quantum dots and external moisture and oxygen is reduced, the stability of the modified quantum dots in the active monomer is improved, and the stability of the quantum dot optical film is enhanced. Description of the Drawings
[0029] Figure 1 : Chemical reaction formula of the copolymerization of isobornyl acrylate, n - butyl acrylate and maleic anhydride, and schematic diagram of the key characteristic unit structure.
[0030] Figure 2 : Schematic diagram of the typical characteristic structure 1 formed by the action of the random copolymer containing maleic anhydride and the quantum dots.
[0031] Figure 3 : Schematic diagram of the typical characteristic structure 2 formed by the action of the random copolymer containing maleic anhydride and the quantum dots.
[0032] Figure 4 : Molecular weight distribution curve (GPC curve) of the random copolymer containing maleic anhydride prepared in Example 1.
[0033] Figure 5 : Molecular weight distribution curve (GPC curve) of the random copolymer containing maleic anhydride prepared in Example 2.
[0034] Figure 6 : Nuclear magnetic resonance spectrum of the random copolymer containing maleic anhydride prepared in Example 3.
[0035] Figure 7 : Fourier transform infrared spectrum of the random copolymer containing maleic anhydride prepared in Example 3.
[0036] Figure 8 : Change in chromaticity coordinate X of the quantum dot optical film prepared with conventional quantum dot encapsulation glue and the quantum dot optical film prepared with quantum dots modified with a random copolymer containing maleic anhydride at high temperature and high humidity (60 o °C & 90% RH).
[0037] Figure 9 : Change in luminance L of the quantum dot optical film prepared with conventional quantum dot encapsulation glue and the quantum dot optical film prepared with quantum dots modified with a random copolymer containing maleic anhydride at high temperature and high humidity (60 o °C & 90% RH).
[0038] Figure 10 : Change in chromaticity coordinate X of the quantum dot optical film prepared with conventional quantum dot encapsulation glue and the quantum dot optical film prepared with quantum dots modified with a random copolymer containing maleic anhydride at high temperature and high humidity (85 o °C & 85% RH).
[0039] Figure 11 : Change in luminance L of the quantum dot optical film prepared with conventional quantum dot encapsulation glue and the quantum dot optical film prepared with quantum dots modified with a random copolymer containing maleic anhydride at high temperature and high humidity (85 o °C & 85% RH). Detailed implementation manners
[0040] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Example 1
[0041] A random copolymer containing maleic anhydride is polymerized by the RAFT method, and the structural unit ratio of isobornyl acrylate, n-butyl acrylate, and maleic anhydride (MAH) is preset to be 45:45:10. In a pressure-resistant bottle, monomers isobornyl acrylate (19.102 g, 91.800 mmol), n-butyl acrylate (11.700 g, 91.800 mmol), maleic anhydride (2.000 g, 20.400 mmol), 2-(dodecylsulfanylthiocarbonothioylthio)-2-methylpropanoic acid (0.728 g, 2.000 mmol), and di-tert-butyl peroxide (29.2 mg, 0.200 mmol) are added, and 1,4-dioxane (15.000 mL) is used as the solvent. After cooling the monomers in the pressure-resistant bottle to -40 °C, argon is passed through for 30 min to remove air and then sealed. The reaction is polymerized in an 80 °C oil bath for 24 h. After the reaction time ends, the pressure-resistant bottle is placed in an ice-water bath and quickly cooled to room temperature. 15 mL of dichloromethane is added to dissolve the polymerization product, and the solution is slowly dropped into 100 mL of methanol to produce precipitation. The precipitate is repeatedly dissolved and precipitated three times to obtain the polymer. Then, it is vacuum dried at 40 °C for 12 h to obtain 26.491 g of the product.
[0042] According to the preparation process of Example 1, the present invention provides the copolymerization chemical reaction of isobornyl acrylate, n-butyl acrylate, and maleic anhydride, and the schematic diagram of the key characteristic unit structure, as Figure 1 shown. Among them, the typical characteristic structures formed by the interaction of the random copolymer containing maleic anhydride and quantum dots are as Figure 2 and Figure 3 shown. For the random copolymer containing maleic anhydride prepared according to Example 1, its molecular weight distribution curve (GPC) is detected, as Figure 4 shown. The molecular weight distribution curve of the sample shows a single-peak distribution. The GPC results show that the random copolymer containing maleic anhydride has Mn = 10200 Da and Mw / Mn = 1.25.
[0043] The above-prepared random copolymer containing maleic anhydride (10.000 g) is dissolved in isobornyl acrylate (40.000 g), and a cross-linking agent neopentyl glycol diacrylate (1.000 g) and pentaerythritol tetraacrylate (0.800 g) and a photoinitiator benzophenone (2.000 g) are added, and stirred evenly to obtain the glue for quantum dot encapsulation. Example 2
[0044] A random copolymer containing maleic anhydride was polymerized by the RAFT method, and the structural unit ratio of isobornyl acrylate, methyl acrylate, and maleic anhydride (MAH) was preset to be 40:40:20. In a pressure-resistant bottle, monomers isobornyl acrylate (8.486 g, 40.800 mmol), methyl acrylate (3.580 g, 40.800 mmol), maleic anhydride (2.000 g, 20.400 mmol), diisopropylxanthogen disulfide (0.135 g, 0.500 mmol), and azobisisobutyronitrile (98.4 mg, 0.600 mmol) were added, and 1,4-dioxane (10.000 mL) was used as the solvent. After cooling the monomers in the pressure-resistant bottle to -40 °C, argon was introduced for 30 min to remove air and then sealed. The reaction was carried out in an oil bath at 65 °C for 10 h. After the reaction time ended, the pressure-resistant bottle was placed in an ice-water bath and quickly cooled to room temperature. 10 mL of dichloromethane was added to dissolve the polymerization product, and the solution was slowly dropped into 100 mL of methanol to produce a precipitate. The precipitate was repeatedly dissolved and precipitated three times to obtain the polymer. Then it was vacuum dried at 40 °C for 12 h to obtain 12.700 g of the product.
[0045] For the random copolymer containing maleic anhydride prepared according to Example 2, its molecular weight distribution curve (GPC) was detected, as Figure 5 shown. The molecular weight distribution curve of the sample showed a single-peak distribution. The GPC results indicated that for the random copolymer containing maleic anhydride, Mn = 16000 Da and Mw / Mn = 1.5.
[0046] The random copolymer containing maleic anhydride (5.000 g) prepared above was dissolved in isobornyl acrylate (45.000 g), and crosslinking agents neopentyl glycol diacrylate (1.100 g) and pentaerythritol tetraacrylate (0.600 g), and photoinitiator benzophenone (1.500 g) were added, and stirred evenly to obtain the glue for quantum dot encapsulation. Example 3
[0047] A random copolymer containing maleic anhydride was polymerized by the RAFT method, and the structural unit ratio of isobornyl acrylate, n-butyl acrylate, and maleic anhydride (MAH) was preset to be 45:45:10. In a pressure-resistant bottle, monomers isobornyl acrylate (19.102 g, 91.800 mmol), n-butyl acrylate (11.700 g, 91.800 mmol), maleic anhydride (2.000 g, 20.400 mmol), 2-(dodecylthiocarbonothioylthio)-2-methylpropanoic acid (0.728 g, 2.000 mmol), and azobisisobutyronitrile (109.4 g, 0.667 mmol) were added, and 1,4-dioxane (7.70 g) was used as the solvent. After cooling the monomers in the pressure-resistant bottle to -40 °C, argon was passed through for 30 min to remove air and then sealed. The monomers in the pressure-resistant bottle were reacted and polymerized in an oil bath at 70 °C for 7 h. After the reaction time ended, the pressure-resistant bottle was placed in an ice-water bath and quickly cooled to room temperature. 10 mL of dichloromethane was added to dissolve the polymerization product, and the solution was slowly dropped into 100 mL of methanol to produce precipitation. The precipitate was repeatedly dissolved and precipitated three times to obtain the polymer. Then, it was vacuum dried at 40 °C for 12 h to obtain 12.700 g of the product.
[0048] For the random copolymer containing maleic anhydride prepared in Example 3, its nuclear magnetic resonance spectrum was detected, and the results were as Figure 6 shown. Among them: The chemical shift at 3.49 is the chemical shift of the hydrogen on the methylene after the polymerization of maleic anhydride. According to the integral, the molar fraction of maleic anhydride in the polymer was calculated to be 10%, and the mass fraction was 6.5%. Its Fourier transform infrared spectrum was detected, and the results were as Figure 7 shown. Among them: The characteristic absorption peaks at 1846 cm -1 and 1782 cm -1 are the symmetric and antisymmetric stretching vibration characteristic absorption peaks of the carbonyl group in MAH. Example 4
[0049] A quantum dot film containing a random copolymer of maleic anhydride and a conventional quantum dot film (without the above random copolymer of maleic anhydride) were prepared, and a reliability test was carried out to evaluate the influence of the random copolymer of maleic anhydride on the performance of the quantum dot film. The specific process is as follows: A quantum dot encapsulation glue containing a random copolymer of maleic anhydride was prepared. Specifically: 10 g of the random copolymer of maleic anhydride prepared in Example 1 was dissolved in 40 g of isobornyl acrylate, then 20 g of pentaerythritol tetraacrylate and 2 g of photoinitiator benzophenone were added, and 1 g of crosslinking agent neopentyl glycol diacrylate was added. At room temperature, it was mechanically stirred at a speed of 200 - 500 rpm / min for 60 min to prepare a quantum dot encapsulation glue containing a random copolymer of maleic anhydride.
[0050] Prepare a conventional quantum dot encapsulation glue (without maleic anhydride random copolymer). Specifically: Add 40 g of isobornyl acrylate to 30 g of pentaerythritol tetraacrylate, then add 2 g of photoinitiator benzophenone and 1 g of crosslinker neopentyl glycol diacrylate. At room temperature, stir mechanically at a speed of 200 - 500 rpm / min for 60 min to prepare the conventional quantum dot encapsulation glue.
[0051] Prepare a quantum dot film using a roll-to-roll coating process. Conduct reliability experiments under conditions of high temperature and high humidity (60 o °C & 90% RH), and high temperature and high humidity (85 o °C & 85% RH), etc., and evaluate changes in key parameters such as color coordinate X, brightness L, etc. The results are as Figure 8 , Figure 9 , Figure 10 , Figure 11 shown.
[0052] Specifically: Figure 8 and Figure 9 are quantum dot optical films prepared with conventional quantum dot encapsulation glue, and the changes in color coordinate X and brightness L of quantum dot optical films prepared with quantum dots modified with maleic anhydride-containing random copolymer under high temperature and high humidity (60 o °C & 90% RH); Figure 10 and Figure 11 are quantum dot optical films prepared with conventional quantum dot encapsulation glue, and the changes in color coordinate X and brightness L of quantum dot optical films prepared with quantum dots modified with maleic anhydride-containing random copolymer under high temperature and high humidity (85 o °C & 85% RH).
[0053] After testing for 1000 h under high temperature and high humidity (60 o °C & 90% RH), the brightness of the quantum dot film added with maleic anhydride copolymer is slightly higher than the initial brightness, while for the quantum dot optical film prepared with conventional quantum dot encapsulation glue, the brightness starts to gradually decrease after 200 h.
[0054] After testing for 1000 h under high temperature and high humidity (85 o °C & 85% RH), both film sheets show performance degradation to varying degrees. However, the performance of the quantum dot film added with maleic anhydride copolymer is better than that of the quantum dot optical film prepared with conventional quantum dot encapsulation glue. Generally, at 85 oUnder extreme reliability tests such as C&85%RH, more water molecules and oxygen pass through the barrier film and enter the glue. The water molecules and oxygen will damage the quantum dots, thereby reducing the performance of the quantum dot film. For the quantum dot film incorporated with maleic anhydride copolymer, the performance of color coordinate X and brightness L is a bit better. This indicates that the maleic anhydride copolymer plays a better passivation role on the surface of the quantum dots, thereby improving the performance of the quantum dot film.
Claims
1. A method for preparing a random copolymer containing maleic anhydride, characterized in that, The steps are as follows: Step 1. Disperse acrylate monomers and maleic anhydride in a solvent, and then add a RAFT reagent and an initiator; Step 2. Heat and polymerize under an inert atmosphere to obtain a polymerization product; Step 3. Dissolve the polymerization product, precipitate with a precipitant, and dry to obtain the random copolymer containing maleic anhydride.
2. The preparation method of a random copolymer containing maleic anhydride according to claim 1, characterized in that, The acrylate monomers are: n-butyl acrylate, methyl acrylate, tert-butyl acrylate, ethyl acrylate or isobornyl acrylate; the RAFT reagents are: 2-(dodecylsulfanylthiocarbonothioylthio)-2-methylpropanoic acid, diisopropylxanthogen disulfide, 4-cyano-4-(phenylthiocarbamoylthio)pentanoic acid or ethylxanthic acid; the initiators are: azobisisobutyronitrile, benzoyl peroxide, di-tert-butyl peroxide or dimethyl 2,2'-azobis(2-methylpropionate); the solvents are: toluene, 1,4-dioxane, tetrahydrofuran or N,N-dimethylformamide; the precipitants are: methanol, ethanol, petroleum ether or n-hexane.
3. The preparation method of a random copolymer containing maleic anhydride according to claim 1, characterized in that, The molar ratio of the RAFT reagent, acrylate monomer, maleic anhydride and initiator is 1:(100 - 10000):(5 - 200):(0.1 - 0.3).
4. The preparation method of a random copolymer containing maleic anhydride according to claim 1, characterized in that, The mass ratio of the acrylate monomer to the solvent is 1:(10 - 50).
5. The preparation method of a random copolymer containing maleic anhydride according to claim 1, characterized in that The temperature of the heating reaction is 50 - 80 °C and the time is 12 - 24 h; the temperature of the drying is 40 - 70 °C and the time is 12 - 36 h.
6. The random copolymer containing maleic anhydride prepared by the method according to claim 1, characterized in that, The number-average relative molecular weight of the random copolymer containing maleic anhydride is 500 - 100000 g / mol, and the content of maleic anhydride is 10 - 20 wt%.
7. Use of the random copolymer containing maleic anhydride according to claim 6 in preparing a quantum dot encapsulating glue, characterized in that, The specific application method is as follows: Dissolve the random copolymer containing maleic anhydride in an active solvent, and then add a crosslinking agent and a photoinitiator and stir to obtain the quantum dot encapsulating glue.
8. Use of the random copolymer containing maleic anhydride according to claim 7 in the preparation of a quantum dot encapsulating glue, characterized in that, The active solvent is ethyl acrylate or isobornyl acrylate, and the mass ratio of the active solvent to the random copolymer containing maleic anhydride is 80:20 - 30:70; the crosslinking agent is selected from one or more of pentaerythritol triacrylate, neopentyl glycol diacrylate, pentaerythritol tetraacrylate, diethylene glycol diacrylate and dipentaerythritol hexaacrylate, and the crosslinking agent accounts for 1% - 10% of the total mass of the random copolymer containing maleic anhydride and the active solvent; the photoinitiator is acetophenone, benzophenone or benzoin dimethyl ether, and the photoinitiator accounts for 0.5% - 5% of the total mass of the random copolymer containing maleic anhydride and the active solvent.
9. The quantum dot encapsulating glue prepared by the application according to claim 7, characterized in that, In the quantum dot encapsulating glue, by mass parts, it includes the following components: a total of 100 parts of the random copolymer containing maleic anhydride and the active solvent, 1 - 10 parts of the crosslinking agent, 0.5 - 5 parts of the photoinitiator, wherein the mass ratio of the active solvent to the random copolymer containing maleic anhydride is 80:20 - 30:
70.
10. Use of the quantum dot encapsulation glue according to claim 9 in the photocuring encapsulation of quantum dots, characterized in that, When the quantum dot encapsulating glue is used for the photocuring encapsulation of quantum dots, the quantum dots account for 2% - 10% of the mass of the glue.