CN106829974A - A kind of preparation method of single dispersing, the Nano particles of silicon dioxide of small size - Google Patents

Abstract

The invention discloses a method for preparing monodisperse and small-sized silicon dioxide nanoparticles, which belongs to the technical field of nanoparticle preparation. It is to add alkyl silicate, lithium hydroxide monohydrate and other basic compounds to the alcohol and water solvent system, and the mass ratio of lithium hydroxide to other basic compounds is 1:0~650; ~50°C, 100~500rpm stirring conditions, react for 1~8 hours; after the reaction, centrifuge the reaction solution to remove the supernatant, wash the centrifuged product 1~2 times, and then wash it with the same alcohol solvent as previously used for 2~ 3 times, and then dry the product at 50-80°C to obtain pure monodisperse, small-sized (3-200nm) silica particles. The present invention prepares silicon dioxide nanoparticles by one-step in-situ growth, without the need for multi-step injection of silicon sources or additional introduction of seeds, and without the introduction of other impurities (such as various surfactants such as cations, anions, and neutrals), so , the preparation method is simpler and the product is easier to purify.

Description

A preparation method of monodisperse, small-sized silica nanoparticles

technical field

The invention belongs to the technical field of nanoparticle preparation, and in particular relates to a method for preparing monodisperse and small-sized silicon dioxide nanoparticles.

Background technique

Silica particles have broad application prospects in the fields of heterogeneous catalysis, film formation, gelation, polishing, high-performance ceramic technology and chromatographic filling. The traditional preparation of silica particles is widely used method (J. ColloidInterface Sci. 1968, 26, 62-69). This method generally prepares spherical silicon dioxide particles by hydrolyzing and condensing tetraethyl orthosilicate in an alcohol-water mixed solvent with different concentrations of ammonia water as a catalyst. The size range of silica particles prepared by this method is generally adjustable from 10 to 500nm (J.Colloid Interface Sci.1992,154,481-501), and the obtained large-size particles (>200nm) have a relatively uniform particle size, while small-size particles (<200nm) Poor monodispersity (J. Eur. Ceram. Soc. 1994, 14, 205-214). In order to realize the simple and effective preparation of monodisperse and small-sized silica particles, researchers have developed a variety of preparation methods. Arriagada et al. used the inverse microemulsion method to prepare silica particles with uniform particle size and adjustable size from 30 to 60 nm (J.Colloid Interface Sci.1999, 221, 210-220); Cao Ao also proposed to use inverse microemulsion Emulsion method to prepare monodisperse silica particles with adjustable size between 20-200nm (Chinese invention patent publication number: CN 101913611A). However, the inverse microemulsion method requires a large amount of difficult-to-remove surfactants, which often have an adverse effect on particle properties. Tsapatsis et al. proposed to use basic biomolecules (such as lysine or arginine) as a catalyst, and through hydrolysis and condensation in a two-phase emulsion system composed of tetraethylorthosilicate and water, to obtain a biphasic biomolecule with a size of about 5nm. Silicon oxide particles (Chem.Mater.2006,18,5814-5816; Pub.No.: US 2008/0213883A1), the reaction time of this technology needs more than 24 hours, and due to the instability of the two-phase system used, it is difficult to The size of the particles is regulated. Yokoi et al. improved the method of preparing silica particles catalyzed by lysine. Octane and water constituted a relatively stable two-phase system. Tunable silica particles (J.Am.Chem.Soc.2006,128,13664-13665; Chem.Mater.2009,21,3719-3729; Pub.No.: US 2008/0311397A1; Pub.No. : US 2011/0151260A1). Due to the strong electrostatic interaction between lysine and silicic acid molecules, no matter whether D-lysine, L-lysine or their mixtures are used, the particle size cannot be regulated in a larger size range. In order to solve this problem, Kitaev et al proposed to use silica particles synthesized by lysine method as seeds, and use the method of regrowth to obtain silica particles with adjustable size in the range of 15-200 nm (Langmuir 2008, 24, 1714-1720 ), but this method is difficult to avoid secondary or multiple nucleation in large-scale production, and the particle polydispersity value is high, which will have an adverse effect on particle uniformity.

Particle polydispersity is a measure of the width of particle size distribution, which can be expressed by particle size deviation. The conventional calculation method is to select more than 200 particles from the transmission electron microscope photos, measure their particle sizes, and then calculate their size deviation (J. Colloid Interface Sci. 2000, 232, 102-110). The smaller the deviation, the narrower the particle size distribution, the more uniform the particle size, and the lower the corresponding particle polydispersity value. Particles were considered monodisperse when the particle polydispersity value was <5% (Langmuir 2008, 24, 1714-1720.).

Contents of the invention

The technical problem to be solved by the present invention is to overcome the problems existing in the background technology and provide a simple and effective preparation method of monodispersed and small-sized (3-200nm) silicon dioxide particles. The silicon dioxide nanoparticles with small size and uniform particle size prepared by the invention have uniform structure and polydispersity value can be controlled below 5%.

In the technical solution, the introduction of lithium hydroxide plays a key role in regulating the size of the silica particles and improving the uniformity of the silica particles. It can accelerate the hydrolysis rate of alkyl silicates, promote the rapid nucleation of silicate monomers, and form more primary particles, and at the same time promote the effective separation of particle nucleation and growth processes, so that particles can follow the classic Nucleation-growth mode" to prevent the adverse effects of secondary or multiple nucleation after nucleation on particle uniformity. In addition, at the initial stage of the alkyl silicate reaction, if a small amount of lithium hydroxide is added alone, it can promote the rapid hydrolysis, condensation and nucleation of the silicon source. Due to the small amount of lithium hydroxide, it is consumed rapidly at the initial stage of the reaction, and after the rapid nucleation of the particles, the growth process becomes slower, and the final particle size is smaller and more uniform.

A method for preparing silica particles with a small size and uniform particle size according to the present invention is characterized in that: in an alcohol-water solvent system (the volume ratio of water to alcohol is 1:4-99), adding an alkyl Silicate, the final concentration is 1-300g/L; add lithium hydroxide monohydrate, the final concentration of lithium hydroxide is 0.002-0.2g/L; add other basic compounds, the final concentration is 0-20g/L , and the mass ratio of lithium hydroxide to other basic compounds is 1:0 to 650; then react for 1 to 8 hours at 20 to 50°C and 100 to 500 rpm (rev/min) under stirring conditions; The reaction solution was centrifuged to remove the supernatant, and the centrifuged product was washed 1-2 times with water, and then washed 2-3 times with the same alcohol solvent used before, and then dried at 50-80°C to obtain a pure monodisperse , Small size (3-200nm) silica particles.

The alcohol solvent refers to methanol, ethanol, propanol or mixtures thereof. The structure of the alkyl silicate can be represented by Si(R') _m (OR) _n , wherein m and n are integers, and m+n=4, m=0~3, n=1~4, R and R' are methyl, ethyl, propyl or butyl, and R and R' can be the same or different; the alkyl silicate specifically refers to: when m=0, n=4, R Respectively methyl, ethyl, propyl and butyl; when m=1, n=3, m=2, n=2 or m=3, n=1, R' and R can be methyl, ethyl , Propyl and butyl; Added in the reaction can be one or a mixture of the above-mentioned alkyl silicates.

The other basic compounds refer to sodium hydroxide, potassium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, choline, basic amino acid , one or a mixture of several in ammonia water.

Beneficial effects of the present invention:

Since the method of the present invention adopts the reaction of a mixed reagent of alkyl silicate and lithium hydroxide or lithium hydroxide and other basic compounds, through one-step in-situ growth, there is no need to inject silicon sources in multiple steps or additionally introduce seeds, etc. method without introducing other impurities (such as various surfactants such as cations, anions, and neutrals), so the preparation method is simpler and the product is easier to purify. In addition, the method for synthesizing monodisperse and small-sized silica nanoparticles has a better effect on particle size regulation, and the particle size can be regulated in the range of 3-200nm.

Description of drawings

Fig. 1 is a transmission electron microscope (TEM) image of 3nm silica particles with uniform size prepared in Example 1 of the present invention. The 3nm particles can be seen in the black circles in the image.

Fig. 2 is a transmission electron microscope (TEM) image of 6nm silica particles with uniform size prepared in Example 2 of the present invention.

Fig. 3 is a transmission electron microscope (TEM) image of 15nm silica particles with uniform size prepared in Example 3 of the present invention.

Fig. 4 is a transmission electron microscope (TEM) image of 40nm silica particles with uniform size prepared in Example 4 of the present invention.

Fig. 5 is a transmission electron microscope (TEM) image of 60nm silica particles with uniform size prepared in Example 5 of the present invention.

Fig. 6 is a transmission electron microscope (TEM) image of 90nm silica particles with uniform size prepared in Example 6 of the present invention.

Fig. 7 is a transmission electron microscope (TEM) image of 160nm silica particles with uniform size prepared in Example 7 of the present invention.

Fig. 8 is a transmission electron microscope (TEM) image of 200nm silica particles with uniform size prepared in Example 8 of the present invention.

detailed description

Below are the basic conditions that specific examples of the present invention use, but the scope that the present invention can implement is not limited to these conditions, is not limited to these examples:

Ambient temperature 20°C, 1 atmosphere;

Lithium hydroxide monohydrate (LiOH·H ₂ O), containing 0.57 grams of LiOH per gram.

Tetramethylammonium hydroxide (TMAOH) aqueous solution has a mass fraction of 25%, a density of 1.02 g/mL, and contains 0.26 g of TMAOH per ml.

Ammonia water, mass fraction 25%, density 0.91g/mL, contains 0.23g NH ₃ per ml.

Choline (C ₅ H ₁₅ NO ₂ ) aqueous solution, mass fraction 48.50%, density 1.09 g/mL, contains 0.53 g C ₅ H ₁₅ NO ₂ per ml.

Example 1: Preparation of 3nm silica particles

In the mixed solvent of 50mL propanol and water, the volume ratio of water and alcohol is 1:99 (V/V), first add 0.18mg lithium hydroxide monohydrate (the final mass concentration of lithium hydroxide is 0.002g/L), in When the reaction temperature is 20°C and the stirring speed is 100rpm, add 0.05g methyltriethoxysilane (final mass concentration: 1g/L), continue to stir at 20°C and 100rpm for 1 hour, centrifuge to remove the supernatant after the reaction , wash once with water, then wash twice with propanol, and dry the particles at 60°C to obtain pure 3nm silica particles with uniform particle size, as shown in Figure 1. The particle polydispersity was 4.8% and the yield was 52%.

Embodiment 2: Preparation of 6nm silica particles

In 10 mL of a mixed solvent of propanol and water, the volume ratio of water and alcohol is 1:49 (V/V), first add 0.18 mg of lithium hydroxide monohydrate (the final mass concentration of lithium hydroxide is 0.01 g/L), and the reaction When the temperature is adjusted to 25°C and the stirring speed is stable to 200rpm, add 0.5g tetramethyl orthosilicate (final mass concentration: 50g/L), continue to stir at 25°C and stirring speed of 200rpm for 3 hours, centrifuge after the reaction Remove the supernatant, wash once with water, then wash twice with propanol, and then dry the particles at 60°C to obtain pure 6nm silica particles with uniform particle size, as shown in Figure 2. The particle polydispersity was 4.5% and the yield was 56%.

Embodiment 3: Preparation of 15nm silica particles

In 100mL of mixed solvent of ethanol and water, the volume ratio of water and alcohol is 1:24 (V/V), first add 3.51mg of lithium hydroxide monohydrate (the final mass concentration of lithium hydroxide is 0.02g/L) and 2mL of mass Ammonia solution with a fraction of 25% (the final mass concentration of _NH3 is 4.60g/L), the mass ratio of lithium hydroxide to ammonia is 1:230, when the reaction temperature is adjusted to 30°C and the stirring speed is stabilized at 300rpm, add 10g Tetraethyl orthosilicate (final mass concentration 100g/L), continue to stir at 30°C and 300rpm for 6 hours. After the reaction is over, centrifuge to remove the supernatant, wash once with water, and then wash twice with ethanol. ℃ to dry the particles to obtain pure 15nm silica particles with uniform particle size, as shown in Figure 3. The particle polydispersity was 4.2% and the yield was 62%.

Example 4: Preparation of 40nm silica particles

In 200mL of mixed solvent of ethanol and water, the volume ratio of water and alcohol is 1:79 (V/V), first add 17.55mg of lithium hydroxide monohydrate (final mass concentration of lithium hydroxide is 0.05g/L), 0.25g Sodium hydroxide (final mass concentration 1.25g/L) and 1g L-lysine (final mass concentration 5g/L), the mass consumption of lithium hydroxide and other alkali (total mass of sodium hydroxide and L-lysine ) ratio is 1:125, when the reaction temperature is adjusted to 40°C and the stirring speed is stabilized to 400rpm, add 40g of ethyltriethoxysilane (final mass concentration 200g/L), and continue to stir at 40°C and 400rpm for 8 hours, after the reaction is over, centrifuge to remove the supernatant, wash once with water, then wash twice with ethanol, and dry the particles at 60°C to obtain pure 40nm silica particles with uniform particle size, as shown in Figure 4. The particle polydispersity was 4.5% and the yield was 70%.

Example 5: Preparation of 60nm silica particles

In 500mL of mixed solvent of methanol and water, the volume ratio of water and alcohol is 1:19 (V/V), first add 175.44mg of lithium hydroxide monohydrate (the final mass concentration of lithium hydroxide is 0.20g/L) and 40mL of mass The fraction is 25% ammonia solution (final mass concentration of _NH3 is 18.40g/L), the mass ratio of lithium hydroxide to ammonia is 1:91, when the reaction temperature is adjusted to 50°C and the stirring speed is stable to 500rpm, add 135g Tetrabutyl orthosilicate (final mass concentration 270g/L), continue to stir at 50°C and 500rpm for 6 hours, after the reaction, centrifuge to remove the supernatant, wash once with water, then wash twice with methanol, 50 ℃ to dry the particles to obtain pure 60nm silica particles with uniform particle size, as shown in Figure 5. The particle polydispersity was 4.0% and the yield was 76%.

Example 6: Preparation of 90nm silica particles

In 1.0L of mixed solvent of methanol and water, the volume ratio of water and alcohol is 1:9 (V/V), first add 58.77mg of lithium hydroxide monohydrate (final mass concentration of lithium hydroxide is 0.03g/L), 90.0 mg potassium hydroxide (final mass concentration 0.09g/L) and 84mL mass fraction are 25% ammonia solution (NH _The final mass concentration 19.32g/L), the mass consumption of lithium hydroxide and other alkalis (sodium hydroxide and The total mass of ammonia) ratio is 1:647, when the reaction temperature is adjusted to 25°C and the stirring speed is stabilized to 200rpm, add 300g tetrapropyl orthosilicate (final mass concentration 300g/L), and continue at 25°C and 200rpm Stir under low pressure for 6 hours. After the reaction, centrifuge to remove the supernatant, wash once with water, then wash twice with methanol, and dry the particles at 70°C to obtain pure 90nm silica particles with uniform particle size, as shown in Figure 6. The particle polydispersity was 3.5% and the yield was 81%.

Example 7: Preparation of 160nm silica particles

In 5.0L mixed solvent of ethanol and water, the volume ratio of water and alcohol is 1:4 (V/V), first add 0.44g lithium hydroxide monohydrate (final mass concentration of lithium hydroxide is 0.05g/L), 0.57 mL mass fraction is 48.5% choline aqueous solution (choline final mass concentration 0.06g/L) and 50mL mass fraction is ₂₅ % ammonia solution (NH final mass concentration 2.30g/L), lithium hydroxide and other The mass dosage of alkali (total mass of choline and ammonia) ratio is 1:47, the reaction temperature is adjusted to 25°C, and when the stirring speed is stabilized to 200rpm, add 90g tetraethyl orthosilicate (final mass concentration 18g/L), Continue to stir at 25°C and 200rpm for 3 hours. After the reaction, centrifuge to remove the supernatant, wash once with water, then wash twice with methanol, and then dry the particles at 80°C to obtain pure 160nm bismuth with uniform particle size. Silicon oxide particles, as shown in Figure 7. The particle polydispersity was 3.8% and the yield was 86%.

Example 8: Preparation of 200nm silica particles

In the mixed solvent of 5.0L ethanol and water, the volume ratio of water and alcohol is 1:9 (V/V), first add 1.48g lithium hydroxide monohydrate (final mass concentration of lithium hydroxide is 0.17g/L), 67.3 mL mass fraction is 25% tetramethylammonium hydroxide aqueous solution (the final mass concentration 3.50g/L of tetramethylammonium hydroxide) and 60g L-lysine (final mass concentration 12g/L), lithium hydroxide and The mass dosage of other bases (total mass of tetramethylammonium hydroxide and L-lysine) ratio is 1:91, when the reaction temperature is adjusted to 30°C and the stirring speed is stabilized to 250rpm, add 75g tetraethyl orthosilicate (final mass concentration 15g/L), continue stirring at 30°C and 250rpm for 3 hours. After the reaction, centrifuge to remove the supernatant, wash once with water, then wash twice with ethanol, and dry the particles at 50°C. Pure 200nm silica particles with uniform particle size were obtained, as shown in Figure 8. The particle polydispersity was 2.7% and the yield was 90%.

Claims (8)

1. a kind of single dispersing, the preparation method of the Nano particles of silicon dioxide of small size, it is characterised in that：In alcohol, aqueous solvent body In system, alkyl silicate, its final concentration of 1~300g/L are added；Add a hydronium(ion) lithia, lithium hydroxide it is final concentration of 0.002~0.2g/L；Other alkali compounds are added, its final concentration of 0~20g/L, and lithium hydroxide and other alkaline chemical combination The quality amount ratio of thing is 1：0~650；Then under 20~50 DEG C, 100~500rpm stirring conditions, react 1~8 hour；Instead Supernatant is removed into reaction solution centrifugation after should terminating, centrifugation product is first washed 1~2 time, then with molten with the identical alcohol for above being used Agent is washed 2~3 times, afterwards dries product at 50~80 DEG C, so as to obtain the titanium dioxide silicon grain of pure single dispersing, small size Son.

2. as claimed in claim 1 a kind of single dispersing, the preparation method of the Nano particles of silicon dioxide of small size, its feature exist In：The size range of the Nano particles of silicon dioxide for preparing is 3~200nm.

3. as claimed in claim 1 a kind of single dispersing, the preparation method of the Nano particles of silicon dioxide of small size, its feature exist In：The polydispersity of the Nano particles of silicon dioxide for preparing is less than 5%.

4. as claimed in claim 1 a kind of single dispersing, the preparation method of the Nano particles of silicon dioxide of small size, its feature exist In：Water is 1 with the volume ratio of alcohol：4~99.

5. as claimed in claim 1 a kind of single dispersing, the preparation method of the Nano particles of silicon dioxide of small size, its feature exist In：Alcoholic solvent is methyl alcohol, ethanol, propyl alcohol or their mixture.

6. as claimed in claim 1 a kind of single dispersing, the preparation method of the Nano particles of silicon dioxide of small size, its feature exist In：The structural formula of alkyl silicate is Si (R ')_m(OR)_n, wherein m, n is integer, and m+n=4, m=0~3, n=1~4, R and R ' is methyl, ethyl, propyl group or butyl, and R and R ' are identical or different；The one kind or several in abovementioned alkyl esters of silicon acis is added in reaction The mixture planted.

7. as claimed in claim 6 a kind of single dispersing, the preparation method of the Nano particles of silicon dioxide of small size, its feature exist In：When m=0, n=4, R is methyl, ethyl, propyl group or butyl；M=1, n=3, when m=2, n=2 or m=3, n=1, R ' and R It is methyl, ethyl, propyl group or butyl.

8. as claimed in claim 1 a kind of single dispersing, the preparation method of the Nano particles of silicon dioxide of small size, its feature exist In：Other alkali compounds are NaOH, potassium hydroxide, TMAH, tetraethyl ammonium hydroxide, tetrapropyl hydrogen-oxygen Change the mixture of one or more in ammonium, TBAH, choline, basic amino acid, ammoniacal liquor.