KR100958541B1 - Fabrication of highly dispersable silica/titania core-shell nanoparticles by interfacial sol-gel method - Google Patents

Abstract

FIELD OF THE INVENTION The present invention relates to the preparation of highly dispersible silica / titanium dioxide core-cell nanocomposites, wherein at the surface of silica nanoparticles through an interfacial sol-gel reaction of a titanium dioxide precursor using an additional surface charge introduced into silica colloidal nanoparticles By restricting the reaction, a method for producing a highly dispersible silica / titanium dioxide core-cell nanocomposite is provided.

According to the present invention, it is possible to easily prepare a highly dispersible silica / titanium dioxide core-cell nanocomposite in a simple and economical manner through an interfacial sol-gel reaction using an additional surface charge. Moreover, the silica / titanium dioxide core-cell nanocomposites that can be prepared in the present invention have no limitation on the size of the nanocomposites according to the size of the silica used as the core, and the thickness limitation depends on the amount of the precursor of titanium dioxide. It is possible to manufacture without.

High Dispersibility, Titanium Dioxide, Silica, Interfacial Sol-Gel Reaction, Nanocomposite

Description

Fabrication of highly dispersible silica / titanium dioxide core-cell nanocomposites using interfacial sol-gel reaction {Fabrication of highly dispersable silica / titania core-shell nanoparticles by interfacial sol-gel method}

The present invention relates to titanium dioxide using an interfacial sol-gel method, which occurs only on the surface of silica nanoparticles through the additionally introduced surface charge of silica colloidal nanoparticles (silica colloidal nanoparticles). titania) is coated on silica nanoparticles to provide a method for producing highly dispersible silica / titanium dioxide core-cell nanoparticles.

Materials having a size of 1 to several tens of nanometers are generally referred to as nanomaterials and have superior physical properties compared to conventional bulk materials due to their large surface area. Especially for titanium dioxide used as pigments, photocatalysts, inorganic membranes, semiconductors, optical coatings, etc., titanium dioxide nanoparticles are significantly increased in physical properties compared to bulk titanium dioxide, and thus are applied to applications such as sunscreens and toxic substance removers. have. In particular, the high refractive index (about 2.5) of the titanium dioxide nanoparticles is used in the research for producing a polymer thin film having a high refractive index by producing a titanium dioxide / polymer thin film composite material containing the titanium dioxide nanoparticles as a filler (filler).

In the production of titanium dioxide nanoparticles having these characteristics, it is made by gas phase process, liquid phase process, chloride process, sulfate process, and it is generally used to make titanium dioxide nanoparticles using sol-gel reaction under acid conditions. It can be said that the manufacturing method.

However, in the production of titanium dioxide nanoparticles, it is not easy to prepare nanoparticles due to the rapid reactivity of the titanium dioxide precursor, and the prepared titanium dioxide nanoparticles are grain rather than having the form of individual nanoparticles due to the fast reactivity. Formed, the overall grain size is larger than the actual nanoparticle size. Therefore, the size of titanium dioxide nanoparticles is generally presented through the size obtained through X-ray diffraction (XRD), rather than the size of the grain (grain) produced. However, titanium dioxide nanoparticles, which do not disperse into individual particles and exist as grains, have a surface area that is smaller than the actual nanoparticles can have, so that the titanium dioxide nanoparticles have excellent surface area. The performance is lower than the performance. In particular, when titanium dioxide nanoparticles are introduced into the polymer thin film as a filler, grain size titanium dioxide nanoparticles (usually present in a few micrometers) are factors that inhibit the transmittance of the polymer thin film and the uniformity of the polymer thin film. Since it acts as a urea, it is important to prepare titanium dioxide nanoparticles with high dispersibility. As a method for improving this, many methods have been studied for producing titanium dioxide nanoparticles having good dispersibility by using a surfactant or preparing a titanium dioxide nanoparticle using a polymer template.

In the case of a method for producing titanium dioxide nanoparticles using a surfactant, at low concentrations of surfactant, the role of the surfactant is limited to controlling the structure of the nanoparticle rather than focusing on improving dispersibility, and a high interface In the concentration of the activator, considering the high price of the surfactant, there is a disadvantage in fairness and economics.

In the case of producing titanium dioxide nanoparticles by using the polymer particles as a polymer template, since the size of the polymer template is generally 100 nanometers or more, the method of producing particles of 100 nanometers or less is large. You will have difficulty. In the preparation of transparent high refractive index polymer thin film nanocomposites using titanium dioxide, considering the scattering in visible light, the size of titanium dioxide nanoparticles added as a filler is 30 nanometers, which is 10% of 300 nanometers, the minimum wavelength of visible light. It is appropriate to have a size of about a meter. Therefore, in the case of the titanium dioxide nanoparticles having a size of 100 nanometers prepared by using a polymer template, there is a big problem in terms of the transmittance in the preparation of transparent high refractive index polymer thin film nanocomposites.

Accordingly, the titanium dioxide has a size of less than 100 nanometers while having excellent dispersibility to prepare titanium dioxide nanoparticles for use as a filler in a transparent high refractive index polymer thin film nanocomposite, and is simple, inexpensive, and easy to use. There is a strong demand for a new production method with a method.

An object of the present invention is to solve the problems of the prior art by additionally introducing ammonium ions to the silica nanoparticles by coating titanium dioxide on the silica nanoparticles through an interfacial sol-gel reaction that occurs only on the surface of the silica nanoparticles, silica / dioxide Titanium core-cell nanoparticles are prepared.

It is an object of the present invention to provide a silica-titanium dioxide composite having a core-shell structure prepared by the above method.

After numerous experiments and in-depth studies, the present inventors introduced a method that is completely different from the known methods, and introduced ammonium ions to have an additional charge on the surface of the silica nanoparticles, and then introduced a titanium dioxide precursor to the silica silica nanoparticles. By allowing the interfacial sol-gel reaction to occur only on the surface of the particles, it was confirmed that the production of silica / titanium dioxide core-cell nanoparticles was possible and led to the present invention.

Titanium tetraisopropoxide, titanium butoxide (titanium butoxide) using the interfacial sol-gel method which is limited only on the surface of silica nanoparticles having a size of 1 nanometer to several micrometers ), Coating titanium dioxide through titanium dioxide precursors of titanium ethoxide, titanium oxoxide, and titanium chloride.

Method for producing titanium dioxide nanoparticles coated on silica particles according to the present invention

(A) dispersing the silica nanoparticles in a mixed solution of ethanol and acetonitrile;

(B) introducing an additional ammonium cation to the surface of the silica nanoparticles by introducing an ammonia solution into the dispersion solution;

(C) adding a titanium dioxide precursor to the dispersion solution is adsorbed on the surface of the silica nanoparticles in which the additional ammonium cation is introduced, so that the interfacial sol-gel reaction occurs only on the surface.

The method for producing highly dispersible silica / titanium dioxide core-cell nanoparticles using the interfacial sol-gel method, which proceeds limitedly on the surface of silica nanoparticles by introducing additional ions according to the present invention, has never been reported. As a new method, the problem of dispersibility caused by the conventional method is significantly reduced, and titanium dioxide can be easily produced. It also has the advantage of being able to mass-produce silica / titanium dioxide core-cell nanoparticles through a simple manufacturing method. The highly dispersible silica / titanium dioxide core-cell nanoparticles thus prepared are not only limited in dispersibility but also in size in size smaller than the nanoparticles prepared through the existing polymer template, in particular, smaller than 100 nanometers. It is possible to manufacture without.

In the mixed solution of ethanol and acetonitrile used in step (A), the amount of acetonitrile is preferably 10 to 100 parts by weight based on 100 parts by weight of ethanol. If the amount of acetonitrile is 10 parts by weight or less and the titanium dioxide precursor may be present not only on the surface of the silica nanoparticles but also on the solution, and if it is 100 parts by weight or more, a problem arises in the dispersion of the silica nanoparticles.

The diameter of the silica nanoparticles is not particularly limited and is preferably 5-500 nanometers, and is applicable to particles of micrometer size. The shape is not limited to a specific shape, but spherical particles are preferred. In the case of silica nanoparticles, silica nanoparticles of various sizes and shapes can be prepared using generally known sol-gel reactions, and commercially available colloidal silica can also be used.

When dispersing the silica nanoparticles on the solution, it is preferably 1 to 20 parts by weight based on 100 parts by weight of ethanol. If the amount of silica used is less than 1 part by weight, problems in the manufacturing process cost due to excessive use of aqueous solution may occur. If the amount of silica is 20 parts by weight or more, dispersion of the core-cell nanoparticles, which are not easily dispersed or finally manufactured, in the ethanol solution is dispersed. This can lead to problems such as entanglement with each other.

The temperature at which the silica nanoparticles are dispersed on the solution is not particularly limited, but the temperature is 1 to 30 ° C., and the dispersion time is preferably 10 to 100 minutes.

The added amount of the ammonia solution used in step (B) may be added up to one hundredth the same amount as that of the silica nanoparticles, but is not limited to these ranges and may be more or less than the above ranges.

The temperature at which the adsorption occurs by introducing additional ammonium ions is not particularly limited, but proceeds at a temperature of 1 to 50 ℃, the stirring time for the adsorption is preferably 5 to 120 minutes.

The type of titanium dioxide precursor in step (C) is not limited to a specific precursor, but is not limited to titanium tetraisopropoxide, titanium butoxide, titanium ethoxide, titanium oxysulfate sulfate) and titanium chloride may be used as the precursor.

The amount of the precursor may be added in a weight ratio of one tenth to five times the silica nanoparticles, but is not limited to these ranges and may be more or less than the above ranges.

The reaction time required for the interfacial sol-gel reaction of the precursor of titanium dioxide is preferably 1 to 24 hours, like the general sol-gel reaction, but is not limited thereto, and may be shorter or longer than the above range depending on the type of precursor. The temperature required for the interface sol-gel reaction may be 5 to 60 ° C., but may be higher or lower than the above range depending on the type of precursor.

EXAMPLE

Although specific examples of the present invention will be described with reference to the following Examples, the scope of the present invention is not limited thereto.

Example 1

0.7 g of silica nanoparticles having a diameter of 18 nanometers was dispersed in 50 ml of ethanol and 15 ml of acetonitrile, and an additional 0.4 ml of ammonia solution was added, followed by stirring for 2 hours while additional ammonium ions were adsorbed onto the silica nanoparticles. Be sure to 2.1 ml of titanium tetraisopropoxide was added to the reaction solution, followed by stirring at room temperature for 6 hours to allow a limited interfacial sol-gel reaction only on the surface of the silica nanoparticles. As a result of analyzing the prepared silica-titanium dioxide nanoparticles having a core-cell structure using a transmission electron microscope, a layer of titanium dioxide having a thickness of about 3.5 nanometers was formed on the surface of the silica nanoparticles, and thus the particle size was 25 It was confirmed that the increase to nanometers. In addition, as a result of analyzing the core-cell nanoparticles through a particle size analyzer, after the reaction of titanium dioxide, the size of the particles was increased compared to the silica nanoparticles, and thus the same result as that of the transmission electron microscope was obtained. Figure 2 discloses the particle size analysis results of the silica-titanium dioxide particles of the core-cell structure prepared in Example 1. As can be seen in Figure 2, the particle size analysis results, it was confirmed that the particles exist as individual particles without aggregation.

[Example 2]

Using the same method as in Example 1, 2.8 ml of titanium tetraisopropoxide was introduced to allow a limited interface sol-gel reaction on the surface of the silica nanoparticles, and analyzed using a transmission electron microscope. As a result, about 6 nanometers of titanium dioxide layer was formed, and it was confirmed that 30 nanometers of silica-titanium dioxide core-cell nanoparticles were produced, and the same result as the transmission electron microscope was obtained through the particle size analysis result.

As can be seen from FIG. 2, it can be seen that the thickness of the titanium dioxide layer formed on the surface of the silica nanoparticles is related to the addition amount of the titanium dioxide precursor introduced, and as the amount of the titanium dioxide precursor increases, It can be seen that the thickness of the layer becomes thick.

Example 3

Using the same method as in Example 1, 0.7 g of 30 nanometer silica nanoparticles were introduced and 1.4 ml of titanium tetraisopropoxide was introduced to restrict the interfacial sol-gel reaction of titanium dioxide on the surface of the silica nanoparticles. As a result of analysis using a transmission electron microscope, a layer of about 6 nanometers of titanium dioxide was formed, and it was confirmed that 42 nanometers of silica-titanium dioxide core-cell nanoparticles were produced (FIG. 3). From the particle size analysis results, the same results as in the transmission electron microscope were obtained. (Figure 4)

Example 4

Using the same method as in Example 1, using 0.7 g of 30 nanometer silica nanoparticles and 2.1 ml of titanium tetraisopropoxide, titanium dioxide was limited to the surface sol-gel reaction on the surface of the silica nanoparticles. As a result of analysis using a transmission electron microscope, a layer of about 10 nanometers of titanium dioxide was formed, and it was confirmed that 50 nanometers of silica-titanium dioxide core-cell nanoparticles were produced. Through the same results as in the transmission electron microscope was obtained (Fig. 4).

Example 5

Using the same method as in Example 1, 0.7 g of 7 nanometer silica nanoparticles were used and 3.5 ml of titanium tetraisopropoxide was introduced to restrict the interfacial sol-gel reaction of titanium dioxide on the surface of the silica nanoparticles. As a result of analysis using a transmission electron microscope, a layer of about 5 nanometers of titanium dioxide was formed, and it was confirmed that 17 nanometers of silica-titanium dioxide core-cell nanoparticles were produced. Through the same results as the transmission electron microscope was obtained.

Example 6

Using the same method as in Example 1, 0.7 g of 50 nanometer silica nanoparticles were introduced and 0.7 ml of titanium tetraisopropoxide was introduced to restrict titanium dioxide on the surface of the silica nanoparticles. As a result of analysis using a transmission electron microscope, a layer of about 5 nanometers of titanium dioxide was formed, and it was confirmed that 60 nanometers of silica-titanium dioxide core-cell nanoparticles were produced. Through the same results as the transmission electron microscope was obtained.

Example 7

Using the same method as in Example 1, 0.7 g of 100 nanometer silica nanoparticles were introduced and 0.7 ml of titanium tetraisopropoxide was introduced to restrict the interfacial sol-gel reaction on the surface of the silica nanoparticles. As a result of analysis using a transmission electron microscope, a layer of about 10 nanometers of titanium dioxide was formed, and it was confirmed that 120 nanometers of silica-titanium dioxide core-cell nanoparticles were produced. Through the same results as the transmission electron microscope was obtained.

Example 8

Using the same method as in Example 1, 0.7 g of 30 nanometer silica nanoparticles were used and 2.1 ml of titanium butoxide were introduced to cause limited interfacial sol-gel reaction on the surface of the silica nanoparticles. As a result of analysis using a transmission electron microscope, a layer of about 8 nanometers of titanium dioxide was formed, and it was confirmed that 45 nanometers of silica-titanium dioxide core-cell nanoparticles were produced. The same results as in the microscope were obtained.

Example 9

Using the same method as in Example 1, 0.7 g of 30 nanometer silica nanoparticles were used and 2.1 ml of titanium oxysulfate was introduced to restrict the interfacial sol-gel reaction of titanium dioxide on the surface of the silica nanoparticles. As a result of analysis using a transmission electron microscope, a layer of about 10 nanometers of titanium dioxide was formed, and it was confirmed that 50 nanometers of silica-titanium dioxide core-cell nanoparticles were produced. The same results as in the microscope were obtained.

Example 10

Using the same method as in Example 1, 0.7 g of 30 nanometer silica nanoparticles were used and 2.1 ml of titanium ethoxide were introduced to allow limited titanium dioxide to interfacial sol-gel reaction on the surface of the silica nanoparticles. As a result of analysis using a transmission electron microscope, a layer of about 15 nanometers of titanium dioxide was formed, and it was confirmed that 60 nanometers of silica-titanium dioxide core-cell nanoparticles were produced. The same results as in the microscope were obtained.

Example 11

Using the same method as in Example 1, 0.7 g of 30 nanometer silica nanoparticles were used and 2.1 ml of titanium chloride was introduced to cause limited titanium dioxide to interfacial sol-gel reaction on the surface of the silica nanoparticles. As a result of analysis using a transmission electron microscope, a layer of about 7 nanometers of titanium dioxide was formed, and it was confirmed that about 45 nanometers of silica-titanium dioxide core-cell nanoparticles were produced. The same results as in the microscope were obtained.

1 is a transmission electron micrograph of the highly dispersible silica / titanium dioxide core-cell nanocomposite prepared in Example 1 of the present invention;

2 is a particle size analysis result of the highly dispersible silica / titanium dioxide core-cell nanocomposites prepared in Examples 1 and 2 of the present invention;

3 is a transmission electron micrograph of the highly dispersible silica / titanium dioxide core-cell nanocomposite prepared in Example 3 of the present invention;

Figure 4 is a particle size analysis results of the highly dispersible silica / titanium dioxide core-cell nanocomposites prepared in Examples 3 and 4 of the present invention.

Claims (6)

(A) dispersing the silica nanoparticles in a mixed solution of ethanol and acetonitrile; (B) introducing an additional ammonium cation to the surface of the silica nanoparticles by introducing an ammonia solution into the dispersion solution; (C) adding a titanium dioxide precursor to the dispersion solution so as to be adsorbed onto the surface of the silica nanoparticles in which the additional ammonium cation is introduced to cause a limited interfacial sol-gel reaction only on the surface. Method for preparing silica / titanium dioxide core-cell nanocomposites. The method of claim 1, wherein the size of the silica nanoparticles are several nanometers to several micrometers in size. The method according to claim 1, wherein the titanium dioxide precursor is titanium tetraisopropoxide, titanium butoxide, titanium ethoxide, titanium oxysulfate, titanium chloride. The method according to claim 1, wherein the added amount of the titanium dioxide precursor is a weight ratio of one tenth to five times the silica nanoparticles. The process according to claim 1, wherein the interfacial sol-gel reaction temperature is from 5 ° C to 60 ° C. The process according to claim 1, wherein the interfacial sol-gel reaction time is from 1 hour to 24 hours.

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