Single-layer zinc cadmium sulfide nanocrystal coating film and preparation method thereof

Abstract

The invention relates to the field of reversed-phase colloid dispersion systems, nanocrystals and coatings, in particular to a single-layer zinc cadmium sulfide nanocrystal coating and a preparation method thereof. The preparation method comprises the following steps: firstly, mixing a polymer aqueous solution, a metal salt aqueous solution and a solvent, and ultrasonically crushing to form a reversed-phase colloid containing nanocrystalline precursor metal ions; and spin-coating the obtained reversed-phase colloid on a quartz glass sheet for natural air drying, and irradiating by infrared light to form a coating film with the surface containing the nanocrystalline precursor. Placing the coating film in a polymer aqueous solution, carrying out ultrasonic cleaning, and then carrying out ultrasonic cleaning with the same polymer aqueous solution again; finishing the coating film containing the surface precursor from which the free metal ions are removed; finally, the coating film is placed in a sintering furnace with the temperature controlled by a program to be heated and sintered, and the single-layer zinc cadmium sulfide nanocrystalline coating film can be obtained. The coating film is prepared by adopting the reverse phase colloid, cadmium / zinc metal ions can be effectively chelated by using sulfydryl of a sulfydryl polyethylene glycol-block polycaprolactone functional group, and free metal ions are few.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of inverse colloidal dispersion, nanocrystal and coating film, in particular to a single-layer zinc-cadmium sulfide nanocrystal coating film and a preparation method thereof. BACKGROUND

[0002] Nanocrystal coating film refers to a functional coating film formed by closely packed and arranged nanoscale (usually 1-100 nanometers) crystal particles adhering to the surface of a substrate material. Nanocrystal coating film is an important material system that utilizes the special effects of nanoscale grains to achieve specific functional improvements on the surface of a substrate. Its preparation, structure control, performance optimization and application development are very active research directions in the field of current material surface engineering.

[0003] The preparation of nanocrystal coating film usually requires the deposition, nucleation, growth and control of grain size at the nanoscale of atoms on the substrate. Common methods include: 1. Physical vapor deposition method. Including magnetron sputtering: depositing nanocrystal coating on the substrate by sputtering target atoms. Process parameters (power, pressure, temperature, bias) have a great influence on grain size and structure. Pulsed laser deposition: using laser ablation of the target to generate plasma for deposition on the substrate. It can well maintain the composition of the target and easily obtain nanocrystal structure. Arc ion plating: generates high ionization rate metal plasma, with high deposition rate and good adhesion, commonly used for hard nanocrystal coating.

[0004] 2. Chemical vapor deposition: depositing thin films by chemical reaction of gaseous precursors on the surface of the substrate. Nanocrystal coating can be obtained by controlling temperature, pressure, precursor concentration, etc.

[0005] 3. Electrochemical deposition: depositing metal or alloy nanocrystal coating on conductive substrates by electrolysis. Grain refinement is controlled by additives, current density, temperature, etc.

[0006] 4. Sol-gel method: forming sol by hydrolysis and polycondensation of precursors in solution, coating on the substrate, and then heat treatment to form nanocrystal oxide coating.

[0007] 5. Thermal spraying: under certain parameters, some high-speed spraying techniques form nanocrystal coating by rapid solidification of molten or semi-molten particles impacting the substrate.

[0008] The above methods may form nanocrystal structure, but it is relatively difficult to form a single layer with precise control of grain size. SUMMARY

[0009] The purpose of the present application is to use inverse colloids to prepare a single-layer zinc-cadmium sulfide nanocrystal coating film. The preparation method of the single-layer zinc-cadmium sulfide nanocrystal coating film by inverse colloids is carried out according to the following steps: (1) Preparation of inverse colloid containing nanocrystal precursor metal ions At room temperature, a certain amount of a specific polymer aqueous solution, a soluble metal salt mixed aqueous solution and a certain amount of a proper solvent are mixed and then quickly transferred into an ultrasonic crusher, and then crushed at a certain temperature for a certain time to form an inverse colloid containing nanocrystal precursor metal ions.

[0010] In step (1), the specific polymer is a thiol polyethylene glycol block polycaprolactone copolymer (ethylene glycol segment and caprolactone segment ratio of 1:1), and the relative mass average molecular weight is 5000, which is prepared into a 1.0% mass concentration aqueous solution; the soluble metal salt mixed aqueous solution is a mixed salt aqueous solution of zinc nitrate, zinc sulfate or zinc chloride and cadmium nitrate, cadmium sulfate or cadmium chloride, which is prepared into a 1.0% mass concentration aqueous solution (cadmium salt and zinc salt are equal in mass); the solvent is a mixed solvent formed by n-heptane and C4 solvent according to a certain ratio.

[0011] The mass ratio of the specific polymer aqueous solution, the soluble metal salt mixed aqueous solution and the solvent is 3.0-5.0:15.0:80.0; the mass ratio of n-heptane and C4 solvent is 20-60:60-20.

[0012] After the water phase and the oil phase are mixed, the mixture is crushed by an ultrasonic crusher at a power of 200 W at room temperature for 10 minutes.

[0013] (2) Coating film formation of inverse colloid containing nanocrystal precursor metal ions and surface precursor formation At room temperature, the inverse colloid containing nanocrystal precursor metal ions prepared in step (1) is uniformly spin-coated on a clean quartz glass sheet, naturally air-dried, and irradiated at a fixed distance for a fixed time under infrared light of a certain wavelength to form a surface nanocrystal precursor coating film.

[0014] In step (2), the spin-coated coating layer of the inverse colloid containing nanocrystal precursor metal ions prepared in step (1) has a thickness of 500-1000 nanometers. The wavelength of the infrared light is 1000-1200 nanometers, the irradiation distance is 10 centimeters, and the irradiation time is 1-2 hours.

[0015] (3) Removal of free metal ions from the nanocrystal precursor coating film At room temperature, the coating film containing the surface precursor formed in step (2) is placed in a certain concentration of a certain polymer aqueous solution, ultrasonically cleaned for a certain time, and then ultrasonically cleaned again with the same polymer aqueous solution. Finally, the coating film is washed with deionized water and dried to complete the removal of free metal ions from the surface precursor coating film.

[0016] In step (3), the certain polymer is a polyamidoamine dendrimer with an absolute molecular weight of 29000, 14000 or 7000, which is prepared into a 1.0% mass concentration aqueous solution for use.

[0017] Ultrasonic cleaning power 100W, ultrasonic time 10 minutes, twice ultrasonic cleaning conditions are same. The conductivity of the collected rinse water in the deionized water rinse process is less than 2 μs / cm to determine the completion of the rinse process.

[0018] (4) Preparation of single layer of zinc cadmium sulfide nanocrystal coating film At room temperature, the surface precursor containing film prepared in step (3) is removed from the free metal ions, and is placed in a sintering furnace with a program-controlled temperature to be heated and sintered for a certain time. After sintering is completed, cooling is performed, and a single layer of zinc cadmium sulfide nanocrystal coating film is obtained.

[0019] In step (3), the sintering furnace is heated to 500-600℃ at a rate of 10℃ / min, and the sintering time is 3-5h.

[0020] The present application realizes a single layer of zinc cadmium sulfide nanocrystal coating film through a reverse colloidal dispersion system. The coating film prepared by the method has potential application prospects in the fields of photoelectric materials and high-efficiency catalysts.

[0021] The present application has the following advantages: 1. The reverse colloidal preparation uses a thiol polyethylene glycol-block polycaprolactone functional group thiol which can effectively chelate cadmium / zinc metal ions, and the free metal ions are less.

[0022] 2. The nanocrystal precursor metal ion reverse colloidal coating film can make the thiol chelated metal ions migrate to the film surface to form a precursor under infrared irradiation.

[0023] 3. The polyamide-amine dendrimer aqueous solution can remove the free metal ions of the nanocrystal precursor containing coating film; and a single layer of zinc cadmium sulfide nanocrystal coating film can be obtained after the coating film is treated and then heat treated. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 Atomic force microscope image of the single layer of zinc cadmium sulfide nanocrystal coating film prepared in Example 1. DETAILED DESCRIPTION

[0025] The present application will be further described in detail below in combination with examples. Example 1

[0026] (1) Preparation of nanocrystal precursor metal ion reverse colloidal At room temperature, 3.0 grams of 1.0% mass concentration of mercapto polyethylene glycol block polycaprolactone copolymer (ethylene glycol segment and caprolactone segment ratio of 1:1, relative mass average molecular weight of 5000) aqueous solution, 15.0 grams of 1.0% mass concentration of zinc sulfate and cadmium chloride metal salt mixed aqueous solution (cadmium salt and zinc salt are equal in mass) and 60 grams of n-heptane and 20 grams of C4 solvent are mixed and quickly transferred into an ultrasonic crusher, and the ultrasonic crusher is crushed at a power of 200W at room temperature for 10 minutes. Form a nano-crystal precursor metal ion reverse-phase colloid.

[0027] (2) Formation of a coating film containing a nano-crystal precursor metal ion reverse-phase colloid and a surface precursor At room temperature, the nano-crystal precursor metal ion reverse-phase colloid prepared in step (1) is uniformly spin-coated on a clean quartz glass sheet and naturally air-dried to form a 500-nanometer-thick coating layer. The coating layer is placed in infrared light with a wavelength of 1200 nanometers, an irradiation distance of 10 centimeters, and an irradiation time of 1 hour to form a surface nano-crystal precursor coating film.

[0028] (3) Removal of free metal ions from the nano-crystal precursor coating film At room temperature, the coating film containing a surface precursor formed in step (2) is placed in a 1.0% mass concentration of polyamidoamine dendrimer (absolute molecular weight of 29000) aqueous solution, and ultrasonic cleaning is performed at a power of 100W for 10 minutes. The coating film is again ultrasonically cleaned with the polyamidoamine dendrimer aqueous solution, and the two ultrasonic cleaning conditions are the same. Finally, the coating film is rinsed with deionized water, and the conductivity of the rinsing water is less than 2 μs / cm to determine that the rinsing process is complete. After drying, the coating film containing a surface precursor with free metal ions removed is obtained.

[0029] (4) Preparation of a single-layer zinc-cadmium sulfide nano-crystal coating film At room temperature, the coating film containing a surface precursor with free metal ions removed prepared in step (3) is placed in a program-controlled temperature sintering furnace, and the temperature is raised to 500°C at a rate of 10°C / min. The sintering holding time is 5 hours. After sintering and cooling, a single-layer zinc-cadmium sulfide nano-crystal coating film is obtained. Example 2

[0030] (1) Preparation of a nano-crystal precursor metal ion reverse-phase colloid At room temperature, 5.0 grams of 1.0% mass concentration of mercapto polyethylene glycol block polycaprolactone copolymer (ethylene glycol segment and caprolactone segment ratio of 1:1, relative mass average molecular weight of 5000) aqueous solution, 15.0 grams of 1.0% mass concentration of zinc nitrate and cadmium sulfate metal salt mixed aqueous solution (cadmium salt and zinc salt are equal in mass) and 30 grams of n-heptane and 50 grams of C4 solvent are mixed and quickly transferred into an ultrasonic crusher, and the ultrasonic crusher is crushed at a power of 200W at room temperature for 10 minutes. Form a nano-crystal precursor metal ion reverse-phase colloid.

[0031] (2) Formation of coating film and surface precursor containing nanocrystal precursor metal ions At room temperature, the nanocrystal precursor metal ion reverse gel prepared in step (1) was uniformly spin-coated on a clean quartz glass sheet and naturally air-dried to form a 1000-nanometer-thick coating layer. The coating layer was placed under infrared light with a wavelength of 1000 nanometers, an irradiation distance of 10 centimeters, and an irradiation time of 2 hours to form a surface nanocrystal precursor coating film.

[0032] (3) Removal of free metal ions from the nanocrystal precursor coating film At room temperature, the surface precursor coating film formed in step (2) was placed in a 1.0% mass concentration polyamide-amine dendrimer (absolute molecular weight 7000) aqueous solution and ultrasonically cleaned at 100W for 10 minutes. The surface precursor coating film was then ultrasonically cleaned again with the polyamide-amine dendrimer aqueous solution under the same conditions as the first ultrasonic cleaning. Finally, the surface precursor coating film was rinsed with deionized water, and the conductivity of the rinsing water was less than 2 μs / cm to determine that the rinsing process was complete. After drying, the surface precursor coating film with free metal ions removed was obtained.

[0033] (4) Preparation of a single-layer zinc-cadmium sulfide nanocrystal coating film At room temperature, the surface precursor coating film with free metal ions removed prepared in step (3) was placed in a sintering furnace with a program-controlled temperature, and the temperature was raised to 600°C at a rate of 10°C / min. The sintering holding time was 3 hours. After sintering and cooling, a single-layer zinc-cadmium sulfide nanocrystal coating film was obtained. Example 3

[0034] (1) Preparation of nanocrystal precursor metal ion reverse gel At room temperature, 4.0 grams of a 1.0% mass concentration mercapto-polyethylene glycol block polycaprolactone copolymer (ethylene glycol segment and caprolactone segment ratio 1:1, relative mass average molecular weight 5000) aqueous solution, 15.0 grams of a 1.0% mass concentration zinc chloride and cadmium nitrate metal salt mixed aqueous solution (equal mass of cadmium salt and zinc salt), and 20 grams of n-heptane and 60 grams of C4 solvent were mixed and quickly transferred to an ultrasonic crusher. The nanocrystal precursor metal ion reverse gel was formed by ultrasonic crushing at 200W for 10 minutes at room temperature.

[0035] (2) Formation of coating film and surface precursor containing nanocrystal precursor metal ions At room temperature, the nanocrystal precursor metal ion reverse gel prepared in step (1) was uniformly spin-coated on a clean quartz glass sheet and naturally air-dried to form a 1000-nanometer-thick coating layer. The coating layer was placed under infrared light with a wavelength of 1000 nanometers, an irradiation distance of 10 centimeters, and an irradiation time of 2 hours to form a surface nanocrystal precursor coating film.

[0036] (3) Removal of free metal ions from the nanocrystal precursor-containing coating film The surface precursor-containing coating film formed in step (2) is placed in a 1.0% mass concentration aqueous solution of polyamidoamine dendrimers (absolute molecular weight 14000) at room temperature, and is ultrasonically cleaned at 100 W for 10 minutes. The film is then ultrasonically cleaned again using an aqueous solution of polyamidoamine dendrimers, under the same conditions as the first ultrasonic cleaning. Finally, the film is rinsed with deionized water, and the conductivity of the rinse water is measured. If the conductivity is less than 2 μs / cm, the rinsing process is considered complete. The surface precursor-containing coating film is dried, and the removal of free metal ions is complete.

[0037] (4) Preparation of a single layer of zinc cadmium sulfide nanocrystal coating film The free metal ion-removed surface precursor-containing coating film prepared in step (3) is placed in a sintering furnace with a program-controlled temperature, and is heated at a rate of 10°C / min to 550°C. The sintering process is carried out for 4 hours, and the film is then allowed to cool. A single layer of zinc cadmium sulfide nanocrystal coating film is thus obtained.

[0038] The foregoing description of the embodiments is provided to enable any person skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without the use of the inventive faculty. Thus, the present application is not intended to be limited to the embodiments described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a single-layer zinc cadmium sulfide nanocrystalline coating, characterized in that, The preparation method steps are as follows: (1) Preparation of reversed phase colloids containing nanocrystalline precursor metal ions At room temperature, weigh out an aqueous solution of mercapto polyethylene glycol block polycaprolactone copolymer, a mixed salt solution of cadmium salt and zinc salt, and a solvent. After mixing, quickly transfer the mixture into an ultrasonic pulverizer to pulverize it into a reverse colloid containing nanocrystalline precursor metal ions. (2) Formation of coatings and surface precursors containing nanocrystalline precursor metal ion reverse colloids At room temperature, the nanocrystalline precursor metal ion reverse colloid prepared in step (1) is uniformly spin-coated onto a clean quartz glass slide and air-dried naturally. It is then placed under infrared light at a fixed distance to form a nanocrystalline precursor coating film on the surface. (3) Removal of free metal ions from coatings containing nanocrystalline precursors At room temperature, the nanocrystalline precursor coating film formed in step (2) is placed in an aqueous solution of polyamide-amine dendritic polymer, ultrasonically cleaned, and then ultrasonically cleaned again with the same polymer aqueous solution; finally, it is rinsed with deionized water and dried to complete the removal of free metal ions from the surface precursor coating film. (4) Preparation of a single-layer zinc cadmium sulfide nanocrystalline coating At room temperature, the surface precursor coating film containing the free metal ions removed prepared in step (3) is placed in a sintering furnace with a programmed temperature control and heated and sintered. After sintering is completed, it is cooled to obtain a single-layer zinc cadmium sulfide nanocrystalline coating film.

2. The method for preparing a single-layer zinc cadmium sulfide nanocrystalline coating according to claim 1, characterized in that, In step (1), the relative mass-average molecular weight of the mercaptopolyethylene glycol block polycaprolactone copolymer is 5000, wherein the ratio of ethylene glycol segments to caprolactone segments is 1:1, and the mass concentration of the aqueous solution of the mercaptopolyethylene glycol block polycaprolactone copolymer is 1.0%.

3. The method for preparing a single-layer zinc cadmium sulfide nanocrystalline coating according to claim 1, characterized in that, In step (1), the mixed salt solution is a mixed salt solution of equal mass of cadmium salt and zinc salt, the zinc salt is zinc nitrate, zinc sulfate or zinc chloride, the cadmium salt is cadmium nitrate, cadmium sulfate or cadmium chloride, and the mass concentration of the mixed salt solution is 1.0%; the solvent is a mixed solvent formed by n-heptane and C4 solvent in a mass ratio of 20-60:60-20.

4. The method for preparing a single-layer zinc cadmium sulfide nanocrystalline coating according to claim 1, characterized in that, In step (1), the mass ratio of the aqueous solution of mercaptopolyethylene glycol block polycaprolactone copolymer, the mixed salt aqueous solution and the solvent is 3.0-5.0:15.0:80.

0.

5. The method for preparing a single-layer zinc cadmium sulfide nanocrystalline coating according to claim 1, characterized in that, In step (1), the ultrasonic pulverizer is used to ultrasonically pulverize at room temperature with a power of 200W for 10 minutes.

6. The method for preparing a single-layer zinc cadmium sulfide nanocrystalline coating according to claim 1, characterized in that, In step (2), the thickness of the nanocrystalline precursor metal ion reverse colloidal spin-coated coating is 500-1000 nanometers; the infrared light wavelength is 1000-1200 nanometers, the irradiation distance is 10 cm, and the irradiation time is 1-2 hours.

7. The method for preparing a single-layer zinc cadmium sulfide nanocrystalline coating according to claim 1, characterized in that, In step (3), the absolute molecular weight of the polyamide-amine dendritic polymer is 29,000, 14,000 or 7,000, the mass concentration of the polyamide-amine dendritic polymer aqueous solution is 1.0%, the ultrasonic cleaning power is 100W, and the ultrasonic time is 10 minutes.

8. The method for preparing a single-layer zinc cadmium sulfide nanocrystalline coating according to claim 1, characterized in that, In step (4), the sintering furnace is heated to 500-600℃ at a rate of 10℃ / min, and the sintering time is 3-5h.

9. A single-layer zinc cadmium sulfide nanocrystalline coating prepared by the method according to any one of claims 1-8.

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