KR100643211B1 - Method of preparing inorganic nanoparticle-polymer core-shell nanostructure using seeded polymerization - Google Patents

Abstract

The present invention relates to inorganic nanoparticles / polymer core-cell nanocomposites, wherein inorganic nanoparticles are used as a core component, and a certain amount of inorganic nanoparticles are dispersed in a solvent, followed by dispersion of inorganic nanoparticles. After introducing an initiator having properties similar to those of the surface of the particles, monomers were injected, and the surface of the nanoparticles was coated by using a polymer as a shell component using seed polymerization at an appropriate temperature and time. It provides a method for producing a cell nanocomposite.

According to the present invention, an inorganic nanoparticle / polymer core-cell nanocomposite can be easily manufactured using a simple and inexpensive process, and no additional modification process or modifier is required to effectively coat the inorganic nanoparticle surface with a polymer. Has an advantage. In addition, the core-cell nanocomposites that can be prepared through the present invention are not limited to the type, size, and shape of the core component, and can be manufactured without limitation on the type and thickness of the polymer cell. Furthermore, from the process point of view, the core-cell nanocomposites that can be produced in the present invention can be mass-produced and have the advantage of very easy recovery of the nanocomposites.

Seed Polymerization, Surface Properties, Inorganic Nanoparticles / Polymer Core-Cell Nanocomposites

Description

Method of preparing inorganic nanoparticles / polymer core-cell nanocomposites using seed polymerization {Method of preparing inorganic nanoparticle-polymer core-shell nanostructure using seeded polymerization}

1 is a transmission electron micrograph of acicular titanium oxide nanoparticles / polymer core-cell nanocomposites prepared according to an embodiment of the present invention;

2 is a transmission electron micrograph of spherical titanium oxide nanoparticles / polymer core / cell nanocomposites prepared according to an embodiment of the present invention;

3 is a transmission electron micrograph of silica nanoparticles / polymer core / cell nanocomposites prepared according to an embodiment of the present invention;

4 is a Fourier transform infrared spectroscopy (FT-IR) graph of zinc oxide nanoparticles / polymer core-cell nanocomposites prepared according to an embodiment of the present invention;

5 is a Fourier transform infrared spectroscopy (FT-IR) graph of acicular titanium oxide nanoparticles / polymer core-cell nanocomposites prepared according to an embodiment of the present invention;

6 is a Fourier transform infrared spectroscopy (FT-IR) graph of silica nanoparticles / polymer core-cell nanocomposites prepared according to an embodiment of the present invention.

The present invention provides a method of making inorganic nanoparticles / polymer core-cell structure by coating inorganic nanoparticles with polymer using seed polymerization.

Generally, a particle having a size of about 1 to 100 nanometers is called a nanoparticle, and in terms of size, it is a material that is halfway between a molecule and a large lump of solid. In particular, nano-sized titanium oxide and zinc oxide have the property of absorbing ultraviolet rays and emitting electrons or radicals. Therefore, it can be applied as a sunscreen and a photocatalyst. In addition, if the white titanium oxide nanoparticles are used as a filler, it can be used as an e-paper that can express letters by flowing electricity. Silica nanoparticles can be used for the purpose of wide view angle using light scattering of LCD monitor by coating the particle surface with polymer to increase the dispersibility in polymer matrix and other chemical sensors and biosensors. The application of is also possible.

In the case of the inorganic material, when the surface is not treated, the phase separation phenomenon of precipitation and aggregation in the organic mixture occurs due to the high density and polarity of the inorganic material itself in the organic mixture. In particular, when titanium oxide is used for the purpose of sun protection, this phenomenon simultaneously decreases the dispersibility and stability of titanium oxide in the ultraviolet cosmetic formulation, and consequently reduces the sun protection ability. Therefore, in order to solve this problem, various efforts have been made to increase the dispersibility and stability in the organic mixture by coating the surface of the inorganic nanoparticles with a polymer.

The coating of inorganic material with a polymer includes chemical vapor deposition polymerization, a method of dissolving a polymer in a solvent to induce a coating on the surface of an inorganic particle, a dispersion of the inorganic material in a solvent, and then a monomer added to the surface of the inorganic particle. And a method of inducing polymerization.

The vapor deposition method has the advantage of coating the polymer on the surface of the inorganic particles as a thin film with a uniform thickness, but has the disadvantages of complicated manufacturing process, high manufacturing cost, and problems in producing a large amount of particles. .

The method of dissolving a polymer in a solvent and coating the surface of an inorganic material has an advantage of easily preparing core-cell particles coated with a polymer, but has a disadvantage in that agglomeration may occur severely between particles.

Therefore, there is a strong demand for a new manufacturing method capable of mass-producing by a simple and inexpensive process while coating a polymer on the surface of the inorganic nanoparticles.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for preparing inorganic nanoparticles / polymer nanocomposites by coating inorganic nanoparticles with a polymer having a uniform thickness by using a new seed polymerization method to solve these problems of the prior art.

An object of the present invention is to increase the dispersibility in the organic mixture of inorganic nanoparticles through the above method and to reduce the cost through mass production of nanocomposites.

After numerous experiments and in-depth studies, the inventors have dispersed inorganic nanoparticles in a solvent in which monomers can dissolve, and polymerized monomers using initiators with properties similar to those of dispersed inorganic nanoparticles. Inorganic nanoparticles / polymer core-cell nanocomposites are synthesized by directly inducing the polymerization of monomers on the surface of the nanoparticles, and the inorganic nanoparticles / polymer core-cell nanocomposites are dispersed in silicone oil to give no polymer coating. The inventors have found that the dispersibility is significantly improved compared to the inorganic nanoparticles, and the present invention has been achieved.

The present invention is a polymethyl methacrylate (polymethyl methacrylate), polyethylene glycol methacrylate (polyethylglycol-methacrylate) through the seed polymerization using titanium oxide, zinc oxide and silica nanoparticles having a size of several nanometers to several microns And coating with polydivinylbenzene.

Method for producing inorganic nanoparticles coated with a polymer according to the present invention,

(A) dispersing the inorganic nanoparticles in a solvent;

(B) adding an initiator similar to the surface properties of the inorganic nanoparticles to the dispersion solution and allowing the initiator to adsorb to the surface of the inorganic nanoparticles;

(C) adding a monomer to the solution to cause polymerization to occur on the surface of the inorganic nanoparticles;

(D) It consists of the step of drying the obtained particle | grains.

The inorganic nanoparticles used in step (A) are not particularly limited, and polymer nanoparticles may be applied in addition to inorganic nanoparticles. Among them, inorganic nanoparticles such as titanium oxide, zinc oxide and silica nanoparticles are preferable. For example, titanium nanoparticles / zinc oxide nanoparticles for application as sunscreens, silica nanoparticles for the application of wide view angle using light scattering are more preferred. The diameter of the inorganic particles is not particularly limited and is preferably 1-1000 nanometers, and the shape is not limited to a specific shape, but spherical particles or acicular particles are preferable. In the case of silica nanoparticles, a commercially available aqueous solution of silica sol may be used, such as commercially available Ludox TM-40, HS-40, and SM-40 silica sol. In addition, silica particles having a diameter of 50-hundreds of nanometers can be prepared using a commonly known Stober method. The type of solvent used is also not limited, and it is preferable to select a solvent in which the inorganic nanoparticles are well dispersed and the monomers can be dissolved well. In particular, propanol, butanol, ethanol, and methanol ( Methanol, acetone, water, hexane, n-hexane, heptane, methylene chloride, and the like are preferable.

The initiator used in step (B) is not limited to a specific kind, but may be used in consideration of the type of monomer, the surface property of the dispersed inorganic nanoparticles, and the degree of hydrophilicity / hydrophobicity of the solvent used. In particular, a radical initiator using pyrolysis or an oxidizing agent by an oxidation-reduction reaction is preferable, and in the present invention, in the case of radical polymerization, 2,2'-azobisisobutyronitrile (AIBN) or 2,2'- which is a radical initiator is preferred. Particular preference is given to azobis- [2- (2-imidazolin-2-yl) -propane] dihydrochloride. The addition amount of the polymerization initiator is used in the amount known in the art as the amount necessary for the conventional polymerization reaction and may be added, for example, in a weight ratio of one hundredth to one tenth of the monomers, It is not limited, It may be more or less than the said range.

In step (C), the kind of monomer is not limited to a specific monomer, but it is appropriate to select a monomer suitable for the purpose to be produced. In particular, vinyl monomers, styrene, divinylbenzene, acrylonitrile, acrylic acid, acrylamide, vinyl carbazole, methyl methacrylate and the like are preferable. In addition, pyromellitic dianhydride (PMDA), 4,4-oxydianiline (ODA), which can be used as a monomer of polyimide, epoxy, phenol, formaldehyde, melamine, urea, urethane resin Pyrrole, aniline, acetylene, thiophene and the like, which are monomers of the conductive polymer, may also be used. In addition, all of the comonomers (comonomers) capable of preparing a copolymer using them are applicable.

When the monomer is added in step (C), there may be a method of injecting a small amount and a method of injecting at a time, and both methods may be used.

The reaction time required for the polymerization is preferably 1-24 hours, similar to the polymer polymerization reaction time, but is not limited thereto, and may be shorter or longer than the above range depending on the type of monomer.

The temperature required for the polymerization may be 5-100 degrees, but may be higher or lower than the above range depending on the type of monomer, the boiling point of the solvent, the type of the opener, and the like.

The drying method in step (D) may use several methods, but it is preferable to dry under low temperature and atmospheric pressure whenever possible in order to prevent the produced particles from agglomerating with each other in the drying step. However, the present invention is not limited thereto, and an appropriate method may be used depending on the humidity and temperature of the laboratory and the type of solvent used.

Experimental results of titanium oxide (zinc oxide) nanoparticles / polymer nanocomposites were dispersed in 3% by weight of titanium oxide (zinc oxide) nanoparticles / polymer core-cells prepared in silicone oil, and the degree of dispersibility was determined by UV protection index ( Sun Protection Factor (SPF) was measured and measured.

Results of the Silica Nanoparticle / Polymer Nanocomposite The test was performed by dispersing the prepared silica nanoparticle / polymer nanocomposite in a polymer matrix, and the result was measured using an UV-VIS spectroscopy.

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

Example 1

4.0 g of hydrophilic spherical titanium oxide nanoparticles were dispersed in 400 ml of ethanol. In the reaction solution, 0.02 g of cerium ammonium nitrate, an oxidizing agent, was dissolved in a small amount of distilled water and placed in a reactor.

1.6 g of methyl methacrylate as a monomer and 0.4 g of ethylene glycol dimethacrylate were simultaneously added to the reaction solution, followed by polymerization at 60 ° C. for 24 hours.

After the reaction solution was dried at room temperature and tested with silicone oil, it was confirmed that the prepared particles had about 30% improvement in dispersibility in the organic mixture compared to the untreated hydrophilic spherical titanium oxide nanoparticles. In order to confirm by using a Fourier Transform Infrared Spectroscopy (FT-IR), it was confirmed that a C = O peak, which is a typical peak of polymethyl methacrylate, was observed at 1726 cm ⁻¹ .

Example 2

4.0 g of hydrophobically surface modified zinc oxide nanoparticles were dispersed in a reactor containing 400 ml of ethanol. The reaction solution was injected by dissolving 2,2'-azobisisobutyronitrile, a hydrophobic radical initiator, in 1 mL of methylene chloride (CH ₂ Cl ₂ ) solvent to allow the initiator to adsorb on the surface of the zinc oxide nanoparticles. At the same time, 1.6 g of methyl methacrylate and 0.4 g of ethylene glycol methacrylate were injected, and then the reaction solution was stirred at 60 ° C. for 24 hours using a magnetic stirring bar.

The completed solution was dried slowly at room temperature to prevent the particles from being entangled with each other.

As a result of observing the dispersibility of the prepared particles in the organic mixture of the zinc oxide-polymer nanocomposite through the silicone oil, it was confirmed that the dispersibility was improved by about 20% compared to the untreated hydrophobic zinc oxide nanoparticles. In addition, by using a Fourier Transform Infrared Spectroscopy (FT-IR) apparatus to confirm that the polymer polymerization has gone through, it is observed that a C = O peak, which is a typical peak of polymethyl methacrylate, is observed at 1726 cm ⁻¹ . It could be confirmed (see FIG. 4).

Example 3

In a reactor containing 400 ml of ethanol, 4.0 g of hydrophobic surface-modified acicular titanium oxide nanoparticles were dispersed. 2,2'-azobisisobutyronitrile, a hydrophobic radical initiator, was dissolved in 1 mL of methylene chloride (CH ₂ Cl ₂ ) solvent in the reaction solution to allow the initiator to be adsorbed onto the surface of acicular titanium oxide nanoparticles. At the same time, 1.6 g of methyl methacrylate and 0.4 g of ethylene glycol methacrylate were injected, and then the reaction solution was stirred at 60 ° C. for 24 hours using a magnetic stirring bar.

The completed solution was dried slowly at room temperature to prevent the particles from being entangled with each other.

As a result of testing the dispersibility in the organic mixture of the titanium oxide-polymer nanocomposite through the silicone oil, it was confirmed that the dispersibility was improved by about 16% compared to the untreated hydrophobic acicular titanium oxide nanoparticles. In addition, by using a Fourier Transform Infrared Spectroscopy (FT-IR) apparatus to confirm that the polymer polymerization has gone through, it is observed that a C = O peak, which is a typical peak of polymethyl methacrylate, is observed at 1730 cm ⁻¹ . I could confirm it. (See Figure 5)

Example 4

 4.0 g of hydrophilic acicular titanium oxide nanoparticles were dispersed in 400 ml of ethanol. 2,2'-azobis- [2- (2-imidazolin-2-yl) -propane] dihydrochromide, a hydrophilic low-temperature radical initiator, is dissolved in a small amount of distilled water, and then added to a reaction solution, and the hydrophilic initiator is titanium oxide. Adsorption on the surface of the nanoparticles.

2.0 g of methyl methacrylate as a monomer was added to the reaction solution, followed by polymerization at 60 ° C. for 24 hours. The titanium oxide / polymer core-cell nanocomposite was dried at room temperature.

The dried particles had about 20% better dispersibility in the organic mixture compared to the untreated hydrophilic acicular titanium oxide nanoparticles, and were identified by Fourier transform infrared spectroscopy (FT-IR). It was confirmed that the C = O peak (peak) was observed at 1728 cm ⁻¹ .

Example 5

4.0 g of hydrophobic acicular titanium oxide nanoparticles were dispersed in a reactor containing 400 ml of ethanol. A small amount of 2,2'-azobis (4-methoxy-2,4-dimethylvalononitrile) (2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), which is a hydrophobic radical initiator, was added to the reaction solution. The solution was dissolved in 1 mL of methylene chloride (CH ₂ Cl ₂ ) solvent, and then 1.6 g of methyl methacrylate and 0.4 g of divinylbenzene were injected at the same time, and a reaction mixture was prepared using a magnetic stirring bar. The polymerization was carried out at 60 ° C. for 24 hours with stirring.

The reaction solution was dried slowly at room temperature to prevent the particles from being entangled with each other.

As a result of observing the dispersibility of the prepared particles in the organic mixture of the titanium oxide-polymer nanocomposite through the silicone oil, it was confirmed that the dispersibility was improved by about 12% compared to the untreated hydrophobic acicular titanium oxide nanoparticles.

Example 6

After dispersing 5.0 g of hydrophilic acicular titanium oxide nanoparticles in 400 ml of distilled water, the hydrophilic low-temperature radical initiator 2,2'-azobis- [2- (2-imidazolin-2-yl) -propane] dihydrochloride Was dissolved in an appropriate amount of ethanol and added to the reaction solution.

0.4 g of methyl methacrylate as a monomer was added to the titanium oxide nanoparticle dispersion solution having an initiator adsorbed on the surface thereof, and polymerization was performed at a temperature of 60 ° C. for 24 hours.

After the polymerization, the resultant was dried at room temperature, and the dispersibility test of the prepared particles in the organic mixture showed that the dispersibility was improved by about 16% compared to the untreated hydrophilic acicular titanium oxide nanoparticles.

Example 7

1.0 g of silica nanoparticles were dispersed in a reactor containing 400 ml of ethanol. The reaction solution was injected by dissolving 2,2'-azobisisobutyronitrile, a hydrophobic radical initiator, in 1 mL of a methylene chloride (CH ₂ Cl ₂ ) solvent to allow the initiator to be adsorbed onto the surface of the silica nanoparticles. 0.4 g of methyl methacrylate and 0.1 g of ethylene glycol methacrylate were injected at the same time, and then polymerized at 60 ° C. for 24 hours while stirring the reaction solution using a magnetic stirring bar.

The completed solution was dried slowly at room temperature to prevent the particles from being entangled with each other.

The prepared particles were dispersed in polymethylmethacrylate, coated on a cover glass, dried, and then measured for transmittance using an ultraviolet-vis spectroscopy (UV-VIS spectroscopy). The measurement result showed that the transmittance was reduced by 10% compared with the coating with only polymethylmethacrylate. This result can be assumed to be due to the increase in reflectance.

As a result of checking through Fourier transform infrared spectroscopy (FT-IR), it was confirmed that a C = O peak, which is a typical peak of polymethyl methacrylate, was observed at 1721 cm ⁻¹ (see FIG. 6).

Coating of inorganic nanoparticles with polymer using the seed polymerization according to the present invention is a completely new method that has not been reported so far, and uniformly polymers nanoparticles to inorganic nanoparticles directly without adding additives such as emulsifiers or dispersants. Coating is possible. In addition, when the polymer coating caused by the conventional method significantly reduces the aggregation (aggregation) between the inorganic particles, it is possible to prevent the phase separation of the polymer and inorganic nanoparticles from each other. In addition, the inorganic nanoparticles-polymer nanocomposites can be mass-produced through an easy and convenient manufacturing method, and the recovery process is very simple, unlike the previous manufacturing methods, inorganic nanoparticles coated with various polymers in a very inexpensive manner. Polymer composites can be prepared. The inorganic nanoparticles / polymer core-cell nanocomposites thus prepared may be utilized in sunscreens, photocatalysts, electronic paper, and coatings for wide viewing angles.

Claims (9)

Dispersing inorganic nanoparticles having an average particle diameter of several nanometers to several tens of micrometers in a solvent; Adding an initiator to the dispersion solution to adsorb the inorganic nanoparticle surface; And, Introducing a monomer into the solution to allow the monomer to polymerize on the surface of the inorganic nanoparticles; And, A method for producing an inorganic nanoparticle / polymer core cell composite, comprising recovering the prepared core-cell composite. The method according to claim 1, wherein the inorganic nanoparticles as core components are titanium oxide, zinc oxide, or silica nanoparticles. The production method according to claim 1, wherein the solvent is selected from polar solvents such as ethanol, water and methanol and nonpolar solvents such as hexane and heptane. The method of claim 1 wherein the initiator is a pyrolytic radical initiator or a chemical oxidant. The method of claim 1, wherein the initiator uses an initiator having properties similar to the surface properties of the dispersed particles. The method according to claim 1, wherein the cell component polymer is a linear, crosslinkable polymer and a copolymer polymer composed of monomers capable of polymerization by the initiator. The method of claim 1 wherein the polymerization temperature is from 1 degree Celsius to 100 degrees Celsius. The method of claim 1, wherein the polymerization time is from 1 minute to 24 hours. delete

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