A quantum dot surface organic ligand composition and a preparation method thereof

Abstract

The present invention provides a quantum dot surface organic ligand composition and a preparation method thereof. The organic ligand composition is synthesized by azeotropic concentration of pentaethylene glycol monoallyl ether and 3-mercaptopropanol under the action of a stabilizer. There are three synthesis methods for pentaethylene glycol monoallyl ether, namely synthesis method 1, synthesis method 2 and synthesis method 3. Among them, synthesis method 1 uses methanesulfonyl chloride and allyloxyethanol as raw materials, reaction formula 2 uses pentaethylene glycol and allyl bromide as raw materials, and reaction formula 3 uses 4-toluenesulfonyl chloride and allyloxyethanol as raw materials. In the process of synthesizing the organic ligand composition of the present invention, a stabilizer is added, which improves the purity stability and viscosity stability of the organic ligand composition, and also greatly improves the binding force and oxidation stability with the quantum dot material. The azeotropic concentration method can remove fine moisture and completely control the gelation phenomenon caused by moisture, and has low viscosity reproducibility.

Description

Technical Field

[0001] The present invention relates to the field of quantum dots, and specifically relates to a quantum dot surface organic ligand composition and a preparation method thereof. Background Art

[0002] Quantum dots (QD) are semiconductor crystals with nanoscale dimensions, characterized by changing the band gap (Band gap, E g ) according to the size and shape of the particles. Quantum dots are composed of a core, a shell, and a ligand. Among them, the ligand binds to the surface of the quantum dot to play a role in the dispersibility of the quantum dot and preventing the phenomenon of quantum dot aggregation. Usually, the binding force between the organic ligand and the quantum dot and the oxidation stability of the organic ligand are regarded as its main characteristics. In the related market using quantum dots, non-polar organic ligands have emerged, and the above non-polar organic ligands simultaneously contain well-known ester groups or thiol groups.

[0003] Under the trend that quantum dots applied in various devices and the layer applications are gradually thinned, it is appropriate that the surface area of the organic ligand layer on the quantum dot surface is less than 5%. According to the characteristic of the proportion of the organic ligand on the surface of the quantum dot, it is beneficial to achieve low viscosity and uniform physical properties of the organic ligand. However, this organic ligand may generate moisture during the process of synthesizing into a compound. When moisture remains in the synthesized compound, gelation occurs at room temperature, resulting in the problem of high viscosity.

[0004] In addition, the organic ligand also has the following problems, such as low binding force between the organic ligand and the quantum dot, low purity stability and low viscosity stability of the organic ligand, high cost in the process of synthesizing the organic ligand, and difficult removal of residues. Furthermore, there is a need to continuously research and develop a preparation method of a quantum dot surface organic ligand that simultaneously meets the physical properties including optical properties. Summary of the Invention

[0005] Technical Problem to be Solved: The purpose of the present invention is to provide a quantum dot surface organic ligand composition and a preparation method thereof. A stabilizer is added in the preparation method, which effectively improves the purity stability and viscosity stability of the organic ligand composition, can prevent the organic ligand composition from being oxidized, and at the same time can well improve the binding force between the organic ligand composition and the quantum dot material.

[0006] Technical Solution: A quantum dot surface organic ligand composition, wherein the organic ligand composition is synthesized by azeotropic concentration of pentaerythritol tetraallyl ether and 3-mercaptopropanol under the action of a stabilizer.

[0007] Preferably, the stabilizer includes phenolic, thioether, phosphite and amine compounds.

[0008] Preferably, the solvent for azeotropic concentration includes one or more of methanol, butyl acetate, dichloromethane and ethyl acetate.

[0009] Preferably, the structural formula Ⅰ of the organic ligand composition is as follows:

[0010] 。

[0011] Preferably, the specific method for the pentaethylene glycol monoallyl ether and 3-mercaptopropanol to form the organic ligand composition is as follows:

[0012] Put the pentaethylene glycol monoallyl ether, 3-mercaptopropionic acid, p-toluenesulfonic acid and the stabilizer into a reactor, add toluene solvent and then reflux. Finally, remove the solvent by azeotropic concentration to obtain the organic ligand composition:

[0013] 。

[0014] Preferably, the reflux conditions are reflux synthesis at 110 °C to 120 °C for 15 hours.

[0015] Preferably, there are 3 synthesis methods for the pentaethylene glycol monoallyl ether, namely synthesis method 1, synthesis method 2 and synthesis method 3. Among them, synthesis method 1 includes the following steps:

[0016] (1) Put methanesulfonyl chloride and allyloxyethanol into a reactor, then add dichloromethane solvent to keep the temperature at -25 °C, and then add potassium hydroxide solvent. After stirring for 2 hours, remove the solvent by concentration to obtain 2-(allyloxy)ethyl methanesulfonate:

[0017] ;

[0018] (2) Put 2-(allyloxy)ethyl methanesulfonate and tetraethylene glycol into a reactor, add tetrahydrofuran solvent to keep the temperature at -25 °C, add sodium hydride solvent and heat to 80 °C and stir for 24 hours, then filter with diatomaceous earth to remove by-products, and finally concentrate to remove the solvent to obtain pentaethylene glycol monoallyl ether:

[0019] ;

[0020] Synthesis method 2 includes the following steps:

[0021] Add pentaethylene glycol and allyl bromide into a reactor, add tetrahydrofuran solvent to keep the temperature at -25°C, then add potassium tert-butoxide, stir at 80°C for 16 hours, filter by-products and impurities using silica gel, and then remove the solvent by concentration to obtain tetraethylene glycol monoallyl ether:

[0022] ;

[0023] Synthesis method 3 includes the following steps:

[0024] (1) Put 4-toluenesulfonyl chloride and allyloxyethanol into a reactor, add tetrahydrofuran solvent to keep the temperature at -25°C, then add triethylamine solvent, stir for 2 hours, and then remove the solvent by concentration to obtain 2-(allyloxy)ethyl 4-methylbenzenesulfonate:

[0025] ;

[0026] (2) Put 2-(allyloxy)ethyl 4-methylbenzenesulfonate and tetraethylene glycol into a reactor, add tetrahydrofuran solvent, keep the temperature at -25°C, add sodium hydride solvent, heat up to 80°C and stir for 24 hours, then filter with diatomaceous earth to remove by-products, and finally concentrate to remove the solvent to obtain tetraethylene glycol monoallyl ether:

[0027] .

[0028] Beneficial effects:

[0029] 1. In the preparation process of the organic ligand composition of the present invention, a stabilizer is added. The addition of the stabilizer improves the purity stability and viscosity stability of the organic ligand composition, and at the same time can prevent the organic ligand composition from being oxidized, ensuring the preservation binding stability;

[0030] 2. The solvent used in the azeotropic concentration of the present invention includes one or more of methanol, butyl acetate, dichloromethane and ethyl acetate, which can effectively remove the residual moisture and residual substances of the organic ligand composition, and completely control the gelation phenomenon caused by moisture by removing fine moisture through azeotropic concentration, and has low viscosity reproducibility;

[0031] 3. The organic ligand composition of the present invention not only has a low preparation cost, but also greatly improves the binding force and oxidation stability with the quantum dot material. Description of the drawings

[0032] Figure 1 It is a GC change diagram of the quantum dot surface organic ligand composition prepared in Comparative Example 2 without adding a stabilizer over time at room temperature (25°C), where (A) is the GC change after 6 hours at room temperature, (B) is the GC change after 24 hours at room temperature, and (C) is the GC change after 48 hours at room temperature;

[0033] Figure 2 For the GC variation diagram of the surface organic ligand composition of quantum dots prepared in Comparative Example 2 without adding stabilizers over time at low temperature (-5°C), where (A) is the GC variation after 6 hours at low temperature, (B) is the GC variation after 24 hours at low temperature, and (C) is the GC variation after 48 hours at low temperature;

[0034] Figure 3 For the GC diagram of the surface organic ligand composition of quantum dots prepared in Example 1 after being placed at room temperature (25°C) for 48 hours;

[0035] Figure 4 For the property diagram of the surface organic ligand composition of quantum dots stored at room temperature (25°C) for 72 hours, where (A) is Example 3 and (B) is Comparative Example 3. Detailed implementation mode

[0036] The present invention will be further described below in conjunction with the drawings and embodiments. The following embodiments are explanations of the present invention and the present invention is not limited to the following embodiments:

[0037] Example 1

[0038] The organic ligand composition was obtained through Synthesis Method 1, and its preparation process is as follows:

[0039] (1) Methanesulfonyl chloride and allyloxyethanol were added to the reactor in an equivalent ratio of 1:1. Subsequently, 6 times the volume of dichloromethane solvent was added and the temperature was maintained at -25°C. Then, 0.1 equivalent of potassium hydroxide solvent was added based on methanesulfonyl chloride. After stirring for 2 hours, the solvent was removed by concentration to obtain 2-(allyloxy)ethyl methanesulfonate:

[0040] ;

[0041] (2) 2-(allyloxy)ethyl methanesulfonate and tetraethylene glycol were put into the reactor in an equivalent ratio of 1:1. 8 times the volume of tetrahydrofuran solvent was added, and the temperature was maintained at -25°C. 0.1 equivalent of sodium hydride solvent was added based on 2-(allyloxy)ethyl methanesulfonate, and the temperature was raised to 80°C and stirred for 24 hours. Then, diatomaceous earth was used for filtration to remove by-products, and finally the solvent was removed by concentration to obtain tetraethylene glycol monoallyl ether:

[0042] ;

[0043] (3) Charge pentaethylene glycol monoallyl ether and 3-mercaptopropionic acid into a reactor in an equivalent ratio of 1:1. Add p-toluenesulfonic acid (P-TSA) and the stabilizer hydroquinone in an amount of 0.1 equivalent of pentaethylene glycol monoallyl ether respectively. Add toluene solvent in a volume 10 times that of pentaethylene glycol monoallyl ether, and reflux at 110 °C for 15 hours. Finally, add the azeotropic solvent methanol to the reactor for azeotropic concentration to obtain the organic ligand composition:

[0044] .

[0045] Example 2

[0046] The organic ligand composition is obtained by synthesis method 2, and its preparation process is as follows:

[0047] (1) Charge pentaethylene glycol and allyl bromide into a reactor in an equivalent ratio of 1:1. Add 8 times the volume of tetrahydrofuran solvent and keep the temperature at -25 °C. Then add potassium tert-butoxide in an amount of 0.1 equivalent of pentaethylene glycol, stir at 80 °C for 16 hours, filter by-products and impurities with 60-mesh silica gel, and remove the solvent by concentration to obtain pentaethylene glycol monoallyl ether:

[0048] ;

[0049] (1) Charge pentaethylene glycol monoallyl ether and 3-mercaptopropionic acid into a reactor in an equivalent ratio of 1:1. Add p-toluenesulfonic acid and the stabilizer hydroquinone in an amount of 0.1 equivalent of pentaethylene glycol monoallyl ether respectively. Add toluene solvent in a volume 10 times that of pentaethylene glycol monoallyl ether, and reflux at 120 °C for 15 hours. Finally, add the azeotropic solvent ethyl acetate to the reactor for azeotropic concentration to obtain the organic ligand composition:

[0050] .

[0051] Example 3

[0052] The organic ligand composition is obtained by synthesis method 3, and its preparation process is as follows:

[0053] (1) Charge 4-toluenesulfonyl chloride and allyloxyethanol into a reactor in an equivalent ratio of 1:1. Then add 7 times the volume of tetrahydrofuran solvent and keep the temperature at -25 °C. Add triethylamine in an amount of 0.5 equivalent of 4-toluenesulfonyl chloride, stir for 2 hours, and remove the solvent by concentration to obtain 2-(allyloxy)ethyl 4-methylbenzenesulfonate:

[0054] ;

[0055] (2) Charge 2-(allyloxy)ethyl 4-methylbenzenesulfonate and tetraethylene glycol into the reactor in an equivalent ratio of 1:1, add 8 times the volume of tetrahydrofuran solvent, maintain the temperature at -25°C, and then add sodium hydride in an amount of 0.1 equivalent of 2-(allyloxy)ethyl 4-methylbenzenesulfonate. After heating to 80°C and stirring for 24 hours, filter using diatomaceous earth to remove by-products, and finally concentrate to remove the solvent to obtain tetraethylene glycol monoallyl ether:

[0056] ;

[0057] (3) Charge tetraethylene glycol monoallyl ether and 3-mercaptopropionic acid into the reactor in an equivalent ratio of 1:1, add p-toluenesulfonic acid and the stabilizer hydroquinone in amounts of 0.1 equivalent of tetraethylene glycol monoallyl ether respectively, add toluene solvent in an amount of 10 times the volume of tetraethylene glycol monoallyl ether, and reflux at 120°C for 15 hours. Finally, add the azeotropic solvents methanol and ethyl acetate to the reactor for azeotropic concentration to finally obtain the organic ligand composition:

[0058] .

[0059] Comparative Example 1

[0060] This comparative example and Example 1 both obtain the organic ligand composition through Synthesis Method 1. The difference is that no stabilizer is added and the solvent is not removed by azeotropic concentration. The preparation process is as follows:

[0061] (1) Charge methanesulfonyl chloride and allyloxyethanol into the reactor in an equivalent ratio of 1:1, then add 6 times the volume of dichloromethane solvent and maintain the temperature at -25°C. Then add potassium hydroxide solvent in an amount of 0.1 equivalent of methanesulfonyl chloride, stir for 2 hours, and then concentrate to remove the solvent to obtain 2-(allyloxy)ethyl methanesulfonate:

[0062] ;

[0063] (2) Charge 2-(allyloxy)ethyl methanesulfonate and tetraethylene glycol into the reactor in an equivalent ratio of 1:1, add 8 times the volume of tetrahydrofuran solvent, maintain the temperature at -25°C, add sodium hydride solvent in an amount of 0.1 equivalent of 2-(allyloxy)ethyl methanesulfonate, heat to 80°C and stir for 24 hours, then filter using diatomaceous earth to remove by-products, and finally concentrate to remove the solvent to obtain tetraethylene glycol monoallyl ether:

[0064] ;

[0065] (3) Charge pentaethylene glycol monoallyl ether and 3-mercaptopropionic acid into a reactor in an equivalent ratio of 1:1. Add p-toluenesulfonic acid (P-TSA) in an amount of 0.1 equivalent based on pentaethylene glycol monoallyl ether. Add toluene solvent in a volume 10 times that of pentaethylene glycol monoallyl ether. Reflux at 110 °C for 15 hours to finally obtain an organic ligand composition;

[0066] 。

[0067] Comparative Example 2

[0068] Both this comparative example and Example 2 obtained the organic ligand composition through Synthesis Method 2. The difference is that no stabilizer was added. The preparation process is as follows:

[0069] (1) Charge pentaethylene glycol and allyl bromide into a reactor in an equivalent ratio of 1:1. Add tetrahydrofuran solvent in a volume 8 times that of pentaethylene glycol and maintain the temperature at -25 °C. Subsequently, add potassium tert-butoxide in an amount of 0.1 equivalent based on pentaethylene glycol. After stirring at 80 °C for 16 hours, filter by-products and impurities using 60-mesh silica gel and then remove the solvent by concentration to obtain pentaethylene glycol monoallyl ether:

[0070] ;

[0071] (2) Charge pentaethylene glycol monoallyl ether and 3-mercaptopropionic acid into a reactor in an equivalent ratio of 1:1. Add p-toluenesulfonic acid in an amount of 0.1 equivalent based on pentaethylene glycol monoallyl ether. Add toluene solvent in a volume 10 times that of pentaethylene glycol monoallyl ether. Reflux at 120 °C for 15 hours. Finally, add the azeotropic solvent ethyl acetate to the reactor for azeotropic concentration to finally obtain the organic ligand composition:

[0072] 。

[0073] Comparative Example 3

[0074] Both this comparative example and Example 3 obtained the organic ligand composition through Synthesis Method 3. The difference is that the solvent was not removed by azeotropic concentration. The preparation process is as follows:

[0075] (1) Charge 4-toluenesulfonyl chloride and allyloxyethanol into a reactor in an equivalent ratio of 1:1. Subsequently, add tetrahydrofuran solvent in a volume 7 times that of 4-toluenesulfonyl chloride and maintain the temperature at -25 °C. Then add triethylamine in an amount of 0.5 equivalent based on 4-toluenesulfonyl chloride. After stirring for 2 hours, remove the solvent by concentration to obtain 2-(allyloxy)ethyl 4-methylbenzenesulfonate:

[0076] ;

[0077] (2) 2-(Allyloxy)ethyl 4-methylbenzenesulfonate and tetraethylene glycol were charged into a reactor in an equivalent ratio of 1:1, 8 times the volume of tetrahydrofuran solvent was added, the temperature was maintained at -25 °C, and then sodium hydride was added in an amount of 0.1 equivalent of 2-(allyloxy)ethyl 4-methylbenzenesulfonate. After heating to 80 °C and stirring for 24 hours, diatomaceous earth was used for filtration to remove by-products, and finally the solvent was removed by concentration to obtain tetraethylene glycol monoallyl ether:

[0078] ;

[0079] (3) Tetraethylene glycol monoallyl ether and 3-mercaptopropionic acid were charged into a reactor in an equivalent ratio of 1:1. p-Toluenesulfonic acid and the stabilizer hydroquinone were added in amounts of 0.1 equivalent of tetraethylene glycol monoallyl ether respectively. Toluene solvent was added in a volume 10 times that of tetraethylene glycol monoallyl ether, and reflux synthesis was carried out at 120 °C for 15 hours to finally obtain an organic ligand composition:

[0080] .

[0081] Result Analysis

[0082] Purity stability change: The purity stability changes of the quantum dot surface organic ligand compositions in each example were confirmed by chromatography when stored at room temperature (25 °C) and low temperature (-5 °C). The results are shown in Table 1 and Table 2.

[0083] Table 1 Purity stability changes of the quantum dot surface organic ligand composition when stored at room temperature (25 °C)

[0084]

[0085] Table 2 Purity stability changes of the quantum dot surface organic ligand composition when stored at low temperature (-5 °C)

[0086]

[0087] Referring to Table 1, Table 2 and Figure 1 , Figure 2 , Figure 3 it can be seen that compared with the quantum dot surface organic ligand composition added with a stabilizer, for the quantum dot surface organic ligand composition without adding a stabilizer, it can be confirmed that with the passage of time, the reduction rates of purity and structural stability are significantly increased. Compared with storage at room temperature (25 °C), when the quantum dot surface organic matter is stored at low temperature (-5 °C), the reduction rates of purity and structural stability are significantly slowed down.

[0088] Viscosity stability change: Set the temperature of the low-viscosity rotary shaker to 25 °C and the rotation speed to 50 rpm. Measure the viscosity 3 times and calculate the average viscosity. Confirm the viscosity stability changes of the quantum dot surface organic ligand compositions of each example when stored at room temperature (25 °C) and low temperature (-5 °C). The results are shown in Tables 3 and 4.

[0089] Table 3 Viscosity stability changes of the quantum dot surface organic ligand composition when stored at room temperature (25 °C)

[0090]

[0091] Table 4 Viscosity stability changes of the quantum dot surface organic ligand composition when stored at low temperature (-5 °C)

[0092]

[0093] Referring to Tables 3 and 4, it can be seen that when the organic ligand composition prepared by adding a stabilizer according to the examples of the present application is stored at room temperature, compared with the organic ligand composition without adding a stabilizer, it can still maintain a similar viscosity even after a long time. Therefore, it can be confirmed that the purity and structural stability are significantly improved. Compared with storage at room temperature (25 °C), the change in viscosity stability of the organic matter on the surface of the quantum dots slows down significantly when stored at low temperature (-5 °C).

[0094] Evaluation of the removal of residual substances after azeotropic concentration: The organic ligand composition prepared in Example 1 was used for the removal of azeotropic water and residual solvents. The instrument settings of the rotary evaporator were a water bath temperature of 25 °C, a rotation speed of 120 rpm, and a vacuum degree of -0.08 to -0.1 MPa. The moisture and solvent residues of the organic ligand composition after azeotropy were confirmed by gas chromatography and Karl Fischer moisture determination. The results are shown in Table 5 and Figure 3 .

[0095] Table 5 Results of confirming residual substances of the organic ligand composition prepared in Example 1 after azeotropic treatment

[0096]

[0097] Referring to Table 5, it can be seen that in the case of azeotropic concentration using butyl acetate as a solvent, trace amounts of ethylbenzene and a small amount of moisture were detected, but toluene and dichloromethane were not detected. In the case of azeotropic concentration using methanol as a solvent, after two concentrations, neither ethylbenzene, toluene, water nor dichloromethane was detected. Therefore, when preparing the quantum dot surface organic ligand composition of the present invention, it is confirmed that the residual harmful substances can be minimized and removed in the case of azeotropic concentration with butyl acetate or methanol.

[0098] Referring to Figure 4The left - hand picture shows that when the water is removed after azeotropic concentration and stored at room temperature, no gelation phenomenon is shown. Figure 4 The right - hand picture shows that when the organic ligand composition on the surface of the quantum dots contains moisture, a gelation phenomenon is shown.

[0099] In summary, the organic ligand composition on the surface of the quantum dots of the present application is prepared by adding a stabilizer and using azeotropic concentration. Thus, it can be confirmed that it has viscosity stability and purity stability suitable for binding to the surface of quantum dots. By removing fine moisture, the viscosity stability is further enhanced. Thus, the problem of gelation phenomenon can be solved, and residual harmful substances can be effectively removed, so it also has safety.

[0100] Obviously, the above - mentioned embodiments are only examples for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A preparation method of a quantum dot surface organic ligand composition, characterized in that: The organic ligand composition is synthesized by azeotropic concentration of tetraethylene glycol monoallyl ether and 3-mercaptopropanol under the action of a stabilizer. The structural formula Ⅰ of the organic ligand in the organic ligand composition is shown as follows: Ⅰ； The specific method for tetraethylene glycol monoallyl ether and 3-mercaptopropanol to form the organic ligand composition is as follows: Put tetraethylene glycol monoallyl ether, 3-mercaptopropionic acid, p-toluenesulfonic acid and a stabilizer into a reactor, add toluene solvent and then reflux. Finally, remove the solvent by azeotropic concentration to obtain the organic ligand composition; ； Among them, the stabilizer is hydroquinone; the solvents for azeotropic concentration include one or more of methanol, butyl acetate, dichloromethane and ethyl acetate.

2. The preparation method of a quantum dot surface organic ligand composition according to claim 1, wherein: The reflux condition is reflux synthesis at 110 °C to 120 °C for 15 hours.

3. The preparation method of a quantum dot surface organic ligand composition according to claim 1, wherein: There are 3 synthesis methods for tetraethylene glycol monoallyl ether, namely synthesis method 1, synthesis method 2 and synthesis method 3. Among them, synthesis method 1 includes the following steps: (1) Put methanesulfonyl chloride and allyloxyethanol into a reactor, then add dichloromethane solvent to keep the temperature at -25 °C, and then add potassium hydroxide solvent. After stirring for 2 hours, remove the solvent by concentration to obtain 2-(allyloxy)ethyl methanesulfonate; ； (2) Put 2-(allyloxy)ethyl methanesulfonate and tetraethylene glycol into a reactor, add tetrahydrofuran solvent to keep the temperature at -25 °C, add sodium hydride solvent and heat up to 80 °C and stir for 24 hours, then filter with diatomaceous earth to remove by-products, and finally remove the solvent by concentration to obtain tetraethylene glycol monoallyl ether; ； Synthesis method 2 includes the following steps: Put pentaethylene glycol and allyl bromide into a reactor, add tetrahydrofuran solvent to keep the temperature at -25 °C, then add potassium tert-butoxide, stir at 80 °C for 16 hours, filter the by-products and impurities with silica gel, and then remove the solvent by concentration to obtain tetraethylene glycol monoallyl ether; ； Synthesis method 3 includes the following steps: (1) Put 4-toluenesulfonyl chloride and allyloxyethanol into a reactor, add tetrahydrofuran solvent to keep the temperature at -25 °C, then add triethylamine solvent, stir for 2 hours, and then remove the solvent by concentration to obtain 2-(allyloxy)ethyl 4-methylbenzenesulfonate; ； (2) Put 2-(allyloxy)ethyl 4-methylbenzenesulfonate and tetraethylene glycol into a reactor, add tetrahydrofuran solvent, keep the temperature at -25 °C, add sodium hydride solvent and heat up to 80 °C and stir for 24 hours, then filter with diatomaceous earth to remove by-products, and finally remove the solvent by concentration to obtain tetraethylene glycol monoallyl ether; 。

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