CN104550941A - A preparation method of silica@noble metal nanocomposite microspheres - Google Patents

Abstract

The invention discloses a method for preparing silica noble metal nanocomposite microspheres, comprising: 1) preparing silica nanospheres; 2) dispersing them in triple distilled water, adding polyelectrolyte sodium chloride aqueous solution, Obtain polyelectrolyte-modified silicon dioxide nano-microspheres; 3) disperse it in triple-distilled water, add a noble metal salt solution dropwise to obtain polyelectrolyte-modified silicon dioxide nano-microspheres covered with noble metal ions; 4) mix It is dispersed in triple distilled water, and sodium borohydride aqueous solution is added dropwise to obtain silicon dioxide precious metal nanocomposite microspheres. Under the reaction conditions of 25°C and room temperature, the present invention uses water as the medium, does not need to use organic solvents, and does not need to go through complicated and cumbersome modification processes, and quickly prepares silica noble metal nanocomposite microspheres with high dispersion and good stability. The method is simple and easy to implement, has good reproducibility, and the reaction device is simple, so that large-scale production can be realized according to production needs.

Description

A kind of preparation method of silicon dioxide precious metal nanocomposite microsphere

technical field

The invention belongs to the technical field of composite material preparation, and relates to a method for preparing silica noble metal nanocomposite microspheres. Specifically, silica is used as the core, polyelectrolyte is used to modify silica, and noble metal nanoparticles and nanoparticles are loaded on the surface of the silica. its preparation method.

Background technique

In addition to the small size effect, quantum tunneling effect, quantum size effect, and surface effect of nanoparticles, noble metal nanoparticles are widely used in chemistry, physics, electronics, optics, and materials science due to their unique physical, chemical, and biological properties. , biology, pharmacology and other disciplines have important research value, in industrial catalysis, detection chemistry, photonic crystals, surface enhanced fluorescence spectroscopy, surface enhanced Raman spectroscopy, antibacterial materials, infrared stealth materials, biomedicine, biological preparations, etc. In terms of application, it also has broad application prospects and has attracted extensive attention from researchers. However, noble metal nanoparticles face a problem in practical applications, that is, nano metal particles have high specific surface area and high surface energy, and are prone to aggregation caused by van der Waals gravity. Due to the agglomeration of noble metal nanoparticles, their application performance is seriously affected. This problem can be solved by depositing noble metal nanoparticles on the surface of a monodisperse solid matrix to form colloidal composite particles, so that the noble metal nanoparticles maintain high stability and activity, and such colloidal composite particles are easy to use and easy to remove from the reaction system. Separation to achieve the purpose of reuse.

SiO ₂ nanospheres are easy to synthesize, have narrow particle size distribution, easy to control particle size, and easy to prepare in large quantities. They have been widely used in various core-shell structures as traditional core layer materials. These nanoshell structures have important potential applications in improving the chemical stability of colloids, enhancing the luminescent properties of the system, biosensing, and drug delivery. The typical representative of the combination of noble metals and the commonly used SiO ₂ core layer is the SiO ₂ M core-shell structure, which is usually a nanocomposite particle composed of a SiO ₂ core and a metal M shell. Because a small amount of expensive metal material can be deposited on the cheap and easy-to-obtain SiO ₂ core layer, the amount of precious metal used is reduced. Therefore, the SiO ₂ M core-shell structure has great potential from an economic point of view.

Methods for preparing SiO ₂ M core-shell structures, including "seed" growth method (Zhang J, Fu Y, Lakowicz J R. Luminescent silica core/silver shell encapsulated with Eu(III) complex[J]. The Journal of Physical Chemistry C, 2009.113(45):19404), sonochemical method (Ye X Y, Zhou Y M, Chen J, et al.Deposition of silver nanoparticles on silica spheres via ultrasound irradiation[J].Applied Surface Science, 2007.253(14):6264 ), electroless plating (Xiu Z L, Wu Y Z, Hao X P, et al.Fabrication of SiO ₂ AgSiO ₂ core-shell microspheres and thermal stability investigation[J]. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2011.386(1): 135), layer-by-layer assembly (Chen G S, Chen C N, Tseng T T, et al. Synthesis, characterization, and antibacterial activity of silver-doped silica nanocomposite particles[J]. Journal of nanoscience and nanotechnology, 2011.11(1): 90 ) and other methods. There are certain shortcomings in the above reactions, that is, the "seed" growth method needs to modify the surface of SiO ₂ , most of the modification process uses silane coupling agents such as APTMS, and the reaction needs to be carried out in an organic solvent system, which takes a long time. The modification conditions are harsh and difficult to control; the sonochemical method requires the reaction to be carried out under anaerobic conditions, which increases the difficulty of the reaction device; the electroless plating method requires the introduction of stannous chloride as a sensitizer, and the final Sn ⁴⁺ is free in the reaction In the system, it is not conducive to environmental protection; the layer-by-layer assembly method needs to be coated with polyelectrolytes of opposite charges multiple times, which takes a long time and consumes a lot of polyelectrolytes.

Contents of the invention

The technical problem to be solved by the present invention is to solve the existing problems such as harsh modification conditions, high requirements for reaction devices, long time consumption, high consumption of organic solvents, and non-compliance with environmental protection requirements.

In order to solve the above problems, the invention provides a method for preparing silica noble metal nanocomposite microspheres, which is characterized in that the specific steps are as follows:

Step 1): Mechanically mix tetraethyl orthosilicate and ethanol at room temperature as A solution, mechanically mix ethanol, three-distilled water and ammonia water at room temperature as B solution, quickly pour A solution into B solution , stirring mechanically at room temperature for 6 to 24 hours to prepare silica nanospheres;

Step 2): Disperse the silica nanospheres obtained in step 1) in triple distilled water to form a 2-50 mg/mL silica emulsion, add 2 mg/mL cationic polyelectrolyte aqueous solution, polyelectrolyte and dioxide The mass ratio of silicon is 1:5 to 1:20, modified by ultrasonication at room temperature for 30 to 120 minutes, centrifugally dispersed, and washed with triple distilled water to obtain polyelectrolyte-modified silica nanospheres;

Step 3): Disperse the polyelectrolyte-modified silica nanospheres obtained in step 2) in three-distilled water to form an emulsion of 2-50 mg/mL, and add 10 mmol/L noble metal salt solution dropwise, and the noble metal salt and poly The mass ratio of electrolyte-modified silicon dioxide is 1:10-100, ultrasonication at room temperature for 30-120 minutes, centrifugal dispersion, and three-distilled water washing to obtain polyelectrolyte-modified silicon dioxide nano-microspheres that deposit noble metal ions ;

Step 4): Disperse the silica nanospheres obtained in step 3) in triple distilled water to form an emulsion of 2-50 mg/mL, add dropwise 50 mmol/L reducing agent sodium borohydride aqueous solution, sodium borohydride aqueous solution and noble metal salt The molar ratio of the aqueous solution is 5:1-1:1, stirred at room temperature for 30-120 minutes, centrifugally dispersed, and washed with triple distilled water to obtain silicon dioxide noble metal nanocomposite microspheres.

Preferably, the molar concentration of ethyl orthosilicate in the step 1) is 0.2 mol/L, the molar concentration of triple-distilled water is 18 mol/L, and the molar concentration of ammonia water is 0.2-1.2 mol/L.

Preferably, the polyelectrolyte in step 2) is polypropylene amine, polyethylene amine or polyisobutylene amine.

Preferably, the concentration of sodium chloride in the aqueous solution containing cationic polyelectrolyte in step 2) is 0.5 mol/L.

Preferably, the noble metal salt is silver nitrate, chloroauric acid or chloroplatinic acid.

The invention provides a simple and feasible method for preparing silicon dioxide noble metal nanocomposite microspheres by using polyelectrolyte modified silicon dioxide, that is, silicon dioxide is used as the core, modified by polyelectrolyte, and precious metals are loaded on the surface nanoparticle approach. Under the reaction conditions of 25°C and room temperature, the present invention uses water as the medium, does not need to use organic solvents, and does not need to go through complicated and cumbersome modification processes, and quickly prepares silica noble metal nanocomposite microspheres with high dispersion and good stability. The method is simple and easy to implement, has good reproducibility, and the reaction device is simple, so that large-scale production can be realized according to production needs. Moreover, the particle size of the noble metal nanoparticles prepared by the patented method is uniformly dispersed and the particle size can be adjusted. This patent can be used to prepare nanocomposite microspheres such as silica silver, silica gold and silica platinum with different particle sizes.

The present invention utilizes the interaction between the hydroxyl groups on the surface of silica and the amino groups in polyelectrolyte molecules through hydrogen bonds, etc., introduces polyelectrolytes on the surface of silica, and utilizes the complexation between silver ions and amino groups in polyelectrolyte molecules to absorb and stabilize silver ions. On the surface of silicon dioxide, silicon dioxide precious metal nanocomposite microspheres of precious metal nanoparticles with high dispersion, good stability and small particle size are prepared through in-situ reduction.

Advantages of the present invention: under mild reaction conditions, using water as a solvent, silica noble metal nanocomposite microspheres with high dispersion, good stability and small diameter noble metal nanoparticles can be rapidly prepared, which can be flexibly prepared according to the needs of production. Adjust the particle size of the noble metal nanoparticles and their coating degree on the silica microspheres. The invention can be applied not only to the preparation of silicon dioxide silver nano-composite microspheres with different particle sizes, but also to the preparation of nano-composite microspheres loaded with gold, platinum and other precious metals on the surface of silicon dioxide. The prepared composite microspheres can be applied in the fields of catalytic chemistry, detection chemistry, photonic crystal, surface-enhanced fluorescence spectroscopy, surface-enhanced Raman spectroscopy, antibacterial materials, infrared stealth materials, biomedicine, and biological preparations.

Description of drawings

Fig. 1 is SiO in embodiment ₁ The transmission electron microscope figure;

Fig. 2 is the transmission electron micrograph of SiO ₂ Ag nanocomposite microspheres in embodiment 1;

Fig. 3 is SiO in embodiment ₂ Transmission electron microscope figure;

FIG. 4 is a transmission electron microscope image of SiO ₂ Ag nanocomposite microspheres in Example 2. FIG.

Detailed ways

In order to make the present invention more comprehensible, preferred embodiments are described in detail below with accompanying drawings.

Example 1

Put 59.20mL triple-distilled water, 38.00mL absolute ethanol, and 2.80mL concentrated ammonia water into a 250mL three-necked flask in sequence, and stir magnetically at 1100rpm for 30min. After mixing evenly, quickly pour the homogeneous mixed solution of 9.00mLTEOS and 91.00mL absolute ethanol into the three-neck flask mentioned above. After 2min, reduce the stirring speed to 400rpm, keep the reaction at 25°C for 6h, and centrifuge at 10000rpm for 5min. Washed several times with water ethanol and triple distilled water to obtain monodisperse _SiO2 nanospheres, which were then dispersed in water with a _SiO2 mass fraction of 2 mg/ml. Transmission electron microscope observation shows that the SiO ₂ nanoparticles obtained by the reaction are spherical, with a diameter of about 100 nm, and are monodisperse, as shown in Figure 1 .

Add 5mL of 2mg/mL PAH aqueous solution (NaCl 0.5M pH 5~6) into 50mL of SiO ₂ dispersion, ultrasonicate at room temperature for 60min, centrifuge at 8000rpm for 5min, wash twice with triple distilled water, and then disperse in 40mL of water. 5.25mL of 10mM AgNO ₃ aqueous solution was added dropwise to the above solution, after ultrasonication for 60min, centrifuged at 8000rpm for 5min, washed with triple distilled water for 3 times, and dispersed in 40ml of water. 5.25mL of 50mM NaBH ₄ was added to the above solution under vigorous stirring at 11000rpm, and after stirring for 30min, the speed was reduced to 600rpm, and the reaction was continued for 30min. Centrifuge at 8000rpm for 5min, wash with absolute ethanol and triple distilled water for 3 times, remove impurities therein, and obtain SiO ₂ Ag nanocomposite microspheres. Observation by transmission electron microscopy showed that the product was a nanocomposite material in which silver nanoparticles were uniformly deposited on the surface of SiO ₂ microspheres, and the particle size of silver nanoparticles was 2-4 nm, as shown in FIG. 2 .

Example 2

Put 55.10 mL triple-distilled water, 36.50 mL absolute ethanol, and 8.40 mL concentrated ammonia water into a 250 mL three-necked flask in sequence, and stir magnetically at 1100 rpm for 30 min. After mixing evenly, quickly pour the uniform mixed solution of 9.00mLTEOS and 91.00mL absolute ethanol into the above-mentioned three-neck flask. After 2min, reduce the stirring speed to 400rpm, keep the reaction at 25°C for 6h, centrifuge at 10000rpm for 5min, and use anhydrous Wash with ethanol and triple distilled water several times to obtain monodisperse _SiO2 nanospheres, which are then dispersed in water with a _SiO2 mass fraction of 2 mg/ml. The transmission electron microscope observation shows that the SiO ₂ nanoparticles obtained by the reaction are spherical, with a diameter of about 300 nm, and are monodisperse, as shown in FIG. 3 .

Add 5mL of 2mg/mL PAH aqueous solution (NaCl 0.5M pH 5-6) into 50mL of SiO ₂ dispersion, ultrasonicate at room temperature for 60min, centrifuge at 8000rpm for 5min, wash twice with triple distilled water, and then disperse in 40mL of water.

5.25mL of 10mM AgNO ₃ aqueous solution was added dropwise to the above solution, after ultrasonication for 60min, centrifuged at 8000rpm for 5min, washed with triple distilled water for 3 times, and dispersed in 40ml of water. 5.25mL of 50mM NaBH ₄ was added to the above solution under vigorous stirring at 11000rpm, and after stirring for 30min, the speed was reduced to 600rpm, and the reaction was continued for 30min. Centrifuge at 8000rpm for 5min, wash with absolute ethanol and triple distilled water for 3 times, remove impurities therein, and obtain SiO ₂ Ag nanocomposite microspheres. Observation by transmission electron microscopy showed that the product was a nanocomposite material in which silver nanoparticles were uniformly deposited on the surface of SiO ₂ microspheres, and the particle size of silver nanoparticles was 2-4 nm, as shown in FIG. 4 .

Comparing the prior art and the present invention for preparing SiO ₂ M, the results are shown in Table 1:

Table 1

Claims (5)

1. a preparation method for silica noble metal nano complex microsphere, is characterized in that, concrete steps are as follows:

Step 1): using ethyl orthosilicate and ethanol at room temperature mechanical agitation mix as A liquid, using ethanol, tri-distilled water, ammoniacal liquor at room temperature mechanical agitation mix as B liquid, pour rapidly A liquid into B liquid, under room temperature, mechanical agitation 6 ~ 24 hours, prepares silicon dioxide nanosphere;

Step 2): by step 1) silica that obtains receives body microballoon and is scattered in tri-distilled water, form the silica emulsion of 2 ~ 50mg/mL, add the aqueous solution of 2mg/mL cationic polyelectrolyte, the mass ratio of polyelectrolyte and silica is 1: 5 ~ 1: 20, within under room temperature ultrasonic 30 ~ 120 minutes, carry out modification, Centrifugal dispersion, through tri-distilled water washing, obtains polyelectrolyte-modified silicon dioxide nanosphere;

Step 3): by step 2) the polyelectrolyte-modified silicon dioxide nanosphere that obtains is scattered in tri-distilled water, form the emulsion of 2 ~ 50mg/mL, dropwise add the noble metal salt aqueous solution of 10mmol/L, the mass ratio of precious metal salt and polyelectrolyte-modified silica is 1: 10 ~ 100, under room temperature ultrasonic 30 ~ 120 minutes, Centrifugal dispersion, through tri-distilled water washing, obtains the polyelectrolyte-modified silicon dioxide nanosphere of depositing noble metal ion;

Step 4): by step 3) silicon dioxide nanosphere that obtains is scattered in tri-distilled water, form the emulsion of 2 ~ 50mg/mL, drip 50mmol/L borane reducing agent sodium hydride aqueous solution, sodium borohydride aqueous solution and noble metal salt aqueous solution mol ratio are 5: 1 ~ 1: 1, at room temperature stir 30 ~ 120 minutes, Centrifugal dispersion, through tri-distilled water washing, obtains silica@noble metal nano complex microsphere.

2. the preparation method of silica@noble metal nano complex microsphere as claimed in claim 1, it is characterized in that, described step 1) in the molar concentration of ethyl orthosilicate be 0.2mol/L, the molar concentration of tri-distilled water is 18mol/L, and the molar concentration of ammoniacal liquor is 0.2 ~ 1.2mol/L.

3. the preparation method of silica@noble metal nano complex microsphere as claimed in claim 1, is characterized in that, described step 2) in polyelectrolyte be polypropylene amine, polyvinylamine or PIBA.

4. the preparation method of silica@noble metal nano complex microsphere as claimed in claim 1, is characterized in that, described step 2) in cation polyelectrolyte the aqueous solution in the concentration of sodium chloride be 0.5mol/L.

5. the preparation method of silica@noble metal nano complex microsphere as claimed in claim 1, it is characterized in that, described precious metal salt is silver nitrate, gold chloride or chloroplatinic acid.