Method for realizing polymer coating surface doping nanocrystals by pickering miniemulsion

Abstract

The present application relates to the field of colloids, surface doping, hydrothermal treatment, and in particular to a method for realizing surface doping of nanocrystals on polymer coating by Pickering miniemulsion. Solid nanocrystal precursor emulsifier capable of stabilizing Pickering emulsion is formed by interfacial reaction, then doping phase is added after maturation, and then doping nanocrystals are formed by hydrothermal treatment, and finally polymer coating surface doping nanocrystals are formed by coating into film. By interfacial reaction, solid emulsifier capable of stabilizing Pickering emulsion can be formed, with original particle size of about 1-2 nanometers and aggregate particle size of about 5 nanometers, and after maturation, maturation nanocrystal precursor with particle size of about 20-30 nanometers can be obtained, and Pickering emulsion after hydrothermal treatment can directly obtain polymer coating surface doping nanocrystals.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of colloids, surface doping, hydrothermal treatment, and in particular to a method for realizing surface doping of nanocrystals on polymer coating using Pickering miniemulsion. BACKGROUND

[0002] Surface doping is a technique that uses doping elements or compounds to change the chemical properties or physical properties of the material surface. Surface doping is widely used in the fields of materials science, nanoscience, and chemical engineering, and the main purpose is to improve the surface conductivity, corrosion resistance, chemical stability, and electrochemical performance of the material, and to improve the application value of the material. Surface doping methods generally include ion implantation method: high-energy ions are implanted into the material surface by an ion accelerator to change the physical and chemical properties of the material. Ion implantation method can select ion species and accurately control the doping concentration and depth to achieve doping. Chemical doping method: such as immersion method and chemical deposition method. These methods can form a new compound layer on the material surface through chemical reaction, thereby changing the material surface properties. Nano-doping method: the stable nano-layer formed by nanoparticles on the material surface can change the material surface properties. Nanoscale particles can achieve more precise control of doping concentration, and surface doping can change the electronic structure of the material, modulate its band gap size, conductivity, magnetism, photocatalytic performance, etc., so that the performance of the material can be improved, and a modified material with new properties and functions is formed.

[0003] Nanocrystals refer to crystalline materials of nanometer size, or nanoparticles with crystalline structure. Nanocrystals have important research value. The electrical and thermodynamic properties of nanocrystals show strong size dependence, so these properties can be controlled through a detailed manufacturing process.

[0004] Polymer thin film refers to a type of organic non-metallic material with a thickness of one micron to several hundred microns, which is mainly composed of polymers such as ordinary or functional polymers. Polymer thin film has good flexibility and plasticity. Currently, the preparation of thin film surface doping nanocrystals generally involves film preparation and surface doping nanocrystals, and there is a problem of separation between the thin film phase and the surface doping nanocrystal phase. SUMMARY

[0005] The purpose of the present application is to use interface reaction to form solid nanocrystal precursors that can stabilize Pickering emulsion, add doping phase after maturation, and then form doped nanocrystals through hydrothermal treatment, and finally coat into film to form polymer coating surface doped nanocrystals.

[0006] The above method is carried out according to the following steps:

[0007] (1) Preparation of solid nanocrystal precursor stabilized Pickering emulsion:

[0008] The oil-soluble polymer, the oily solvent, the oil-soluble metal salt and the deionized water are mixed in a certain mass ratio at room temperature, and then are transferred into a reactor, and are ultrasonically pulverized by an ultrasonic biological pulverizer at a certain temperature for a fixed time; then the water-soluble salt capable of forming a solid nanocrystal precursor is added in a one-time feeding mode, and the ultrasonic pulverization is continuously carried out at a certain temperature for a fixed time by the ultrasonic biological pulverizer, so that a stable Pickering emulsion of the solid nanocrystal precursor is obtained.

[0009] In step (1), the oil-soluble polymer is polystyrene, polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride and a copolymer thereof, etc., and the relative number average molecular weight of the polymer is 1-50,000;

[0010] The oily solvent is benzene, cyclohexane or n-hexane, etc.

[0011] The oil-soluble metal salt is an acetate or an isooctanoate of cadmium, cobalt or nickel;

[0012] The water-soluble salt capable of forming a solid nanocrystal precursor is sodium sulfide or potassium sulfide, etc.

[0013] The mass ratio of the oil-soluble polymer, the oily solvent, the oil-soluble metal salt, the water-soluble salt capable of forming a solid nanocrystal precursor and the deionized water is 1.0-2.0:9.0:0.1-0.5:0.1-0.5:90.0.

[0014] In step (1), the power of the ultrasonic biological pulverizer used for the secondary pulverization is 200 W, the pulverization temperature is controlled to be 5℃, and the pulverization time is 10 minutes.

[0015] (2) The surface doping phase is added after the solid nanocrystal precursor is matured:

[0016] The Pickering emulsion prepared in step (1) is transferred into a pressure container at room temperature, an inert gas is introduced into the pressure container, and the Pickering emulsion is maintained at a certain temperature and time, so that the solid nanocrystal precursor is matured and the Pickering emulsion is transferred into a reactor. Then, a certain amount of the surface doping phase is added, and the surface doping phase is pulverized by an ultrasonic biological pulverizer with a certain power at a certain temperature for a fixed time, so that the surface doping phase is added to the Pickering emulsion of the stable solid nanocrystal precursor.

[0017] In step (2), the pressure container is a stainless steel container capable of bearing a pressure of 10.0 MPa, the inert gas introduced into the pressure container is nitrogen, argon or neon, etc., the pressure is 5-10 MPa, the maturation temperature is 40-60℃, and the maturation time is 60-120 minutes.

[0018] The surface doping phase is a water-soluble or oil-soluble metal salt capable of improving the surface properties of the nanocrystal, the water-soluble metal salt is europium nitrate, yttrium nitrate or samarium nitrate, etc., and the oil-soluble metal salt is n-butyl titanate, copper acetate or cerium isooctanoate, etc.

[0019] The mass ratio of the Pickering emulsion prepared in step (1) and the surface doping phase is 80:0.001-0.005.

[0020] The ultrasonic biological grinder has a power of 100 W, the crushing temperature is controlled at 5 ℃, and the crushing time is 2 minutes.

[0021] (3) preparing the Pickering emulsion of the surface-doped nanocrystals and then coating a film:

[0022] At room temperature, a certain volume of the surface-doped phase prepared in step (2) is added to the Pickering emulsion stabilized by the solid nanocrystal precursor, and then transferred to a fixed-volume high-pressure reaction kettle; then placed in an oven set at a certain temperature for a predetermined time, and the reaction liquid is obtained after hydrothermal treatment. After the reaction liquid is cooled to room temperature, it can be spin-coated or flow-coated into a film, and dried at a set temperature to obtain a polymer coating surface-doped nanocrystal.

[0023] In step (3), the volume ratio of the surface-doped phase prepared in step (2) to the Pickering emulsion stabilized by the solid nanocrystal precursor is 60:100; the hydrothermal treatment is set at a temperature of 120-150 ℃, and the predetermined holding time is 4-6 hours.

[0024] The reaction liquid is spin-coated or flow-coated into a film with a thickness of 0.2-0.3 microns, and the drying temperature after film formation is 80-100 ℃.

[0025] The present application has the following advantages:

[0026] 1. The nanocrystal precursor solid emulsifier can stabilize the Pickering emulsion by interfacial reaction, with an original particle size of about 1-2 nanometers and an aggregate particle size of about 5 nanometers;

[0027] 2. The solid nanocrystal precursor is matured in a high-pressure reaction kettle, and the matured nanocrystal precursor has a particle size of about 20-30 nanometers;

[0028] 3. The surface-doped phase can be widely used, and water-soluble or oil-soluble metal salts can be used for surface-doping nanocrystals;

[0029] 4. The Pickering emulsion after hydrothermal treatment can directly obtain a polymer coating surface-doped nanocrystal.

[0030] 5、The method for realizing surface-doped nanocrystals on polymer coating by Pickering emulsion The surface-doped nanocrystals are formed on the surface of the polymer coating, and the surface-doped nanocrystals and the polymer have good compatibility. The method has advantages in nanometer size and film formation, and can be widely used in optoelectronic films, optical devices, capacitors or some high-end functional occasions. DETAILED DESCRIPTION

[0031] The application will be further described in detail below with examples.

[0032] Example 1

[0033] (1) Preparation of Pickering emulsion stabilized by solid nanocrystal precursor:

[0034] At room temperature, 1.0 grams of polystyrene with a relative number average molecular weight of 50,000, 9.0 grams of benzene, 0.1 grams of cadmium acetate, and 90.0 grams of deionized water were mixed and transferred to a reactor, and then crushed by a 200W ultrasonic biological crusher, with the crushing temperature controlled at 5°C and the crushing time of 10 minutes. Then, 0.1 grams of potassium sulfide was added in one step, and the crushing was continued by the 200W ultrasonic biological crusher, with the crushing temperature controlled at 5°C and the crushing time of 10 minutes. A Pickering emulsion stabilized by solid nanocrystal precursor was obtained. The original particle size of the solid nanocrystal precursor was about 1 nanometer, and the aggregate particle size of the solid nanocrystal precursor was about 5 nanometers. The particle size of the Pickering emulsion particles was 200 nanometers.

[0035] (2) Maturation of solid nanocrystal precursor and then addition of surface doping phase:

[0036] At room temperature, 80 grams of the Pickering emulsion prepared in step (1) was transferred to a pressure container, and 10 MPa of nitrogen gas was introduced and maintained at a maturation temperature of 40°C for 120 minutes. The Pickering emulsion was then transferred to a reactor. Then, 0.001 grams of europium nitrate surface doping phase was added, and then crushed by a 100W ultrasonic biological crusher, with the temperature controlled at 5°C and the crushing time of 2 minutes. The Pickering emulsion stabilized by solid nanocrystal precursor was prepared by adding the surface doping phase. After maturation, a maturation nanocrystal precursor with a particle size of 20 nanometers was obtained.

[0037] (3) Preparation of Pickering emulsion of surface-doped nanocrystals and then film coating:

[0038] The surface doping phase prepared in step (2) is added to the Pickering emulsion stabilized by solid nanocrystal precursors at room temperature and transferred to a 100-mL capacity high-pressure reactor; then placed in an oven at 120°C for 6 hours, and the Pickering emulsion containing surface-doped nanocrystals is obtained after hydrothermal treatment. The reaction solution is cooled to room temperature and spin-coated into a 0.2-μm polymer film, which is dried at 80°C to obtain a polymer coating surface-doped nanocrystal. The polymer coating is rubbed to separate the surface-doped nanocrystals. X-ray diffraction detects the doped nanomaterial, and the diffraction peak of europium-doped cadmium cadmium nanocrystals appears; the average particle size of the nanocrystals is calculated to be 15 nm according to the half-peak width of the diffraction peak. The X-ray photoelectron spectrometer detects that the atomic number of the surface europium element accounts for 8.0% of the total metal atomic number, which is much higher than the actual doping amount.

[0039] Example 2

[0040] (1) Preparation of Pickering emulsion stabilized by solid nanocrystal precursors:

[0041] At room temperature, 2.0 grams of poly(methyl methacrylate) with a relative number-average molecular weight of 10,000, 9.0 grams of benzene, 0.5 grams of nickel isooctanoate, and 90.0 grams of deionized water are mixed and transferred to a reactor, and then pulverized by a 200W ultrasonic biological pulverizer at a pulverizing temperature of 5°C for 10 minutes. Then 0.5 grams of sodium sulfide is added in one batch, and the pulverizing is continued by a 200W ultrasonic biological pulverizer at a pulverizing temperature of 5°C for 10 minutes; a Pickering emulsion stabilized by solid nanocrystal precursors is obtained. The original particle size of the solid nanocrystal precursor is about 2 nanometers, and the aggregate particle size of the solid nanocrystal precursor is about 6 nanometers; the particle size of the Pickering emulsion particles is 250 nanometers.

[0042] (2) Maturation of solid nanocrystal precursors and then addition of surface doping phase:

[0043] At room temperature, 80 grams of the Pickering emulsion prepared in step (1) is transferred to a pressure container, argon gas with a pressure of 5Mpa is introduced, and the maturation temperature is maintained at 60°C for 60 minutes to complete the maturation of the solid nanocrystal precursors and transfer the Pickering emulsion to the reactor. Then 0.005 grams of titanium n-butyl ester surface doping phase is added, and then pulverized by a 100W ultrasonic biological pulverizer at a temperature of 5°C for 2 minutes. The preparation of the Pickering emulsion stabilized by solid nanocrystal precursors with the surface doping phase is completed. The maturation nanocrystal precursors with a particle size of about 30 nanometers are obtained after maturation.

[0044] (3) Preparation of Pickering emulsion of surface-doped nanocrystals and then film coating:

[0045] The surface doping phase prepared in step (2) is added into the Pickering emulsion stabilized by solid nanocrystal precursors at room temperature and transferred into a 100-mL capacity high-pressure reactor; then placed in an oven at a temperature of 150°C for 4 hours, and the Pickering emulsion containing surface-doped nanocrystals is obtained after hydrothermal treatment. The reaction solution is cooled to room temperature and spin-coated into a 0.3-μm polymer film, which is dried at 100°C to obtain a polymer coating surface-doped nanocrystal. The polymer coating is rubbed to separate the surface-doped nanocrystals. X-ray diffraction detection of the doped nanomaterials shows diffraction peaks of titanium-doped nickel sulfide nanocrystals; the average particle size of the nanocrystals is calculated to be 20 nm according to the half-peak width of the diffraction peak. The X-ray photoelectron spectrometer detects that the atomic number of the surface titanium element accounts for 16.0% of the total metal atomic number, which is much higher than the actual doping amount.

[0046] Example 3

[0047] (1) Preparation of Pickering emulsion stabilized by solid nanocrystal precursors:

[0048] At room temperature, 1.5 grams of polyvinyl chloride with a relative number-average molecular weight of 20,000, 9.0 grams of benzene, 0.3 grams of cobalt isooctanoate, and 90.0 grams of deionized water are mixed and transferred into a reactor, and then pulverized by a 200W ultrasonic biological pulverizer at a pulverizing temperature of 5°C for 10 minutes. Then, 0.3 grams of sodium sulfide is added in one batch, and the pulverizing is continued by the 200W ultrasonic biological pulverizer at a pulverizing temperature of 5°C for 10 minutes; a Pickering emulsion stabilized by solid nanocrystal precursors is obtained. The original particle size of the solid nanocrystal precursors is about 2 nanometers, and the aggregate particle size of the solid nanocrystal precursors is about 6 nanometers; the particle size of the Pickering emulsion particles is 230 nanometers.

[0049] (2) Maturation of solid nanocrystal precursors and then addition of surface doping phase:

[0050] At room temperature, 80 grams of the Pickering emulsion prepared in step (1) is transferred into a pressure container, 8 MPa of argon gas is introduced, and the maturation temperature is maintained at 55°C for 90 minutes to complete the maturation of the solid nanocrystal precursors and transfer the Pickering emulsion into the reactor. Then, 0.001 grams of samarium nitrate and 0.002 grams of cerium isooctanoate surface doping phase are added, and then pulverized by a 100W ultrasonic biological pulverizer at a temperature of 5°C for 2 minutes. The preparation of the Pickering emulsion stabilized by solid nanocrystal precursors with the surface doping phase is completed. The maturation of the nanocrystal precursors with a particle size of about 25 nanometers is obtained after maturation;

[0051] (3) Preparation of Pickering emulsion of surface-doped nanocrystals and then film coating:

[0052] The 60 ml surface-doped phase prepared in step (2) is added to the Pickering emulsion stabilized by solid nanocrystal precursor at room temperature and transferred to a 100 ml capacity high-pressure reactor; then placed in an oven at 145°C for 5 hours, and the Pickering emulsion containing surface-doped nanocrystals is obtained after hydrothermal treatment. The reaction solution is cooled to room temperature and then spin-coated into a 0.25 micron polymer film, which is dried at 90°C to obtain a polymer coating surface-doped nanocrystal. Rubbing the polymer coating separates the surface-doped nanocrystals. X-ray diffraction detects the doped nanomaterial, and the spectrum shows the diffraction peaks of samarium and cerium doped cobalt cadmium nanocrystals; according to the half peak width of the diffraction peak, the average particle size of the nanocrystals is 20 nm. X-ray photoelectron spectroscopy detects that the atomic number of surface samarium and cerium elements accounts for 8.0% and 15% of the total metal atomic number, which is much higher than the actual doping amount.

[0053] The above description of the embodiments is to facilitate the understanding and application of the present application by those skilled in the art. Those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without having to go through creative labor. Therefore, the present application is not limited to the embodiments described herein, and any modifications made to the present application by those skilled in the art based on the disclosure of the present application should be within the scope of protection of the present application.

Claims

1. A polymer-coated surface doped with nanocrystals prepared using a Pickering miniemulsion, characterized in that: The method for preparing the surface-doped nanocrystal comprises the following steps: (1) preparing a Pickering emulsion stabilized by a solid nanocrystal precursor: At room temperature, the oil-soluble polymer, the oily solvent, the oil-soluble metal salt and the deionized water are mixed and then transferred into a reactor, and then are ultrasonically pulverized by an ultrasonic biological pulverizer; the water-soluble salt capable of forming the solid nanocrystal precursor is added at one time, and then is ultrasonically pulverized by the ultrasonic biological pulverizer, so as to obtain the Pickering emulsion stabilized by the solid nanocrystal precursor; The oil-soluble polymer is polystyrene, polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride and a copolymer thereof, and the relative number-average molecular weight of the polymer is 10-50 thousand; (2) adding a surface doping phase after maturing the solid nanocrystal precursor: At room temperature, the Pickering emulsion prepared in step (1) is transferred into a pressure container, and then inert gas is introduced, so that the solid nanocrystal precursor is matured and the Pickering emulsion is transferred into a reactor, and then the surface doping phase is added and is pulverized by the ultrasonic biological pulverizer, so as to complete the preparation of the Pickering emulsion in which the surface doping phase is added into the Pickering emulsion stabilized by the solid nanocrystal precursor; The surface doping phase is a water-soluble or oil-soluble metal salt, the water-soluble metal salt is europium nitrate, yttrium nitrate or samarium nitrate, and the oil-soluble metal salt is titanium n-butylate, copper acetate or cerium iso-octoate; (3) preparing a Pickering emulsion containing a surface-doped nanocrystal and then coating a film: At room temperature, the surface doping phase prepared in step (2) is added into the Pickering emulsion stabilized by the solid nanocrystal precursor and is transferred into a high-pressure reaction kettle; then the reaction kettle is placed in an oven set at a certain temperature for heat preservation, and then the reaction liquid is taken out after hydrothermal treatment, so as to obtain the Pickering emulsion containing the surface-doped nanocrystal; the reaction liquid is cooled to room temperature, and then is spin-coated or flow-coated to form a film, and then is dried, so as to obtain a polymer coating layer containing the surface-doped nanocrystal.

2. The polymer-coated surface-doped nanocrystal of claim 1, wherein: In step (1), the oily solvent is benzene, cyclohexane or n-hexane; the oil-soluble metal salt is an acetate or iso-octoate of cadmium, cobalt or nickel; and the water-soluble salt capable of forming the solid nanocrystal precursor is sodium sulfide or potassium sulfide.

3. The polymer-coated surface-doped nanocrystal of claim 1, wherein: In step (1), the mass ratio of the oil-soluble polymer, the oily solvent, the oil-soluble metal salt, the water-soluble salt capable of forming the solid nanocrystal precursor and the deionized water is 1.0-2.0:9.0:0.1-0.5:0.1-0.5:90.

0.

4. The polymer-coated surface-doped nanocrystal of claim 1, wherein: In step (1), the power of the ultrasonic biological pulverizer used for the twice pulverization is 200 W, the pulverization temperature is controlled to be 5℃, and the pulverization time is 10 minutes.

5. The polymer-coated surface-doped nanocrystal of claim 1, wherein: In step (2), the inert gas introduced is nitrogen, argon or neon, and the pressure of the inert gas is 5-10 MPa; the maturing temperature is 40-60℃, and the maturing time is 60-120 minutes.

6. The polymer-coated surface-doped nanocrystal of claim 1, wherein: In step (2), the mass ratio of the Pickering emulsion prepared in step (1) to the surface doping phase is 80:0.001-0.005, the power of the ultrasonic biological pulverizer is 100 W, the pulverization temperature is controlled to be 5℃, and the pulverization time is 2 minutes.

7. The polymer-coated surface-doped nanocrystal of claim 1, wherein: In step (3), the volume ratio of the Pickering emulsion prepared in step (2) and the high-pressure reactor is 60:100; the hydrothermal treatment is set to have a holding temperature of 120-150 DEG C and a predetermined holding time of 4-6 hours.

8. The polymer coating surface doped with nanocrystals as described in claim 1, characterized in that: In step (3), the reaction solution is spin-coated or flow-casted to form a film with a thickness of 0.2-0.3 microns, and the film is dried at a temperature of 80-100 DEG C.