KR20190087174A - Hollow Silica Nanospheres and Preparation Method Thereof - Google Patents

Abstract

The present invention relates to a hollow-type silica sphere and a method for manufacturing the same. More specifically, the present invention relates to: the method for manufacturing a novel hollow-type silica sphere capable of controlling a size of a hollow and a thickness of the hollow since a non-porous silica sphere is converted to a nano-silica sphere having a hollow form through a solid phase conversion; and the hollow-type silica sphere manufactured by the method.

Description

Hollow Silica Nanospheres and Preparation Method Thereof ", which is a method of preparing a hollow silica silica spheres,

The present invention relates to a hollow spherical silica spheres and a manufacturing method thereof, and more particularly to a silica spherical spherical silica spherical spherical silica spherical silica spherical silica spherical silica spherical silica spherical silica spherical silica spherical spherical silica spherical spherical silica spherical spherical silica spherical spherical silica And a pupil-shaped silica spheres produced by the method.

Hollow silica materials can be used in various fields. This is because hollow pores inside the silica spheres can be used to stably store or support molecules or metals required in the pores.

One of the most widely used fields is the transportation of medicinal materials. Because it can store large organic molecules that can be used as medicines in the pupil, pupil-type silica can be safely delivered to the place where the medicinal substance is to be expressed, and used as a medicinal substance transporter to discharge the medicinal substance have. The same principle can be used as a transporter capable of storing enzyme molecules inside a pupil and discharging it at a desired location. This possibility is known to be possible because the silica itself is a substance that has little harm to the human body.

In addition, it can be used as a catalyst material carrier having a core @ shell structure by stably supporting metal nanoparticles in the pore-forming silica. The most commonly used types of catalysts in various chemical catalyst processes are heterogeneous catalysts, which are composed of phases different from the reaction phase. Most of the reaction phase is a liquid phase or a gas phase, and the heterogeneous catalyst used in this case is mainly composed of a solid phase. In order to facilitate the utilization of the catalyst, a catalyst system supported on a carrier (mainly a nanoporous substance having a large surface area) capable of stably fixing a substance showing catalytic activity (mainly a metal nanoparticle form) can be constructed and utilized as a solid catalyst do. In this case, a small amount of small metal nanoparticles can be supported in the pore-type silica in the case of the pore-type silica, and the catalyst form of the Core @ Shell structure thus produced may reduce the aggregation of the metal nanoparticles dispersed in the periphery . That is, when the metal nanoparticles are supported on a nanoporous substance carrier having a wide surface area, the aggregation of the metal nanoparticles arranged close to each other due to the high temperature thermal energy supplied during the general heterogeneous catalytic reaction proceeding at a high temperature / Occurs. As a result, the surface area per unit mass of the metal nanoparticles is reduced as compared with the catalyst material in the initial state, which leads to a decrease in catalytic activity. It is known that this problem can be solved when metal nanoparticles are dispersed and supported in the porous silica.

Porous silica materials can be made using a variety of synthetic methods. For example, a variety of silica precursors can be synthesized into nonporous silica spheres, the surface of which is coated with an electrolyte organic layer, and then the inside of the silica spheres can be selectively dissolved by using hydrofluoric acid or a basic aqueous solution. In a similar manner, the surface of the non-porous silica spheres is grafted with a covalent organic functional group to cover the surface with an organic layer, and the inside of the silica spheres can be selectively dissolved by using hydrofluoric acid or a basic aqueous solution.

As another manufacturing method, a silica sphere including a template is formed in the process of forming a silica sphere by polymerizing a silica precursor by adding an organic template or a solid-type template together with a silica precursor together with a silica precursor in the course of synthesizing a silica sphere , And the mold may be selectively burned or melted to prepare a pore-form silica having a cavity therein. At this time, the organic mold can mainly utilize a polymer having a large molecular weight, an oil molecule having a large molecular weight, or organic molecules having a surfactant structure.

The manufacturing methods of the known pore-type silica are complicated, and the production cost is high because they have to be manufactured through various steps. Processes using molds have also been simplified in comparison with the post-treatment process in which pores are produced by treatment with hydrofluoric acid or a basic solution, but the prices of polymers and macromolecular surfactants used as templates are somewhat higher. In addition, the pore-form silicas prepared by this method may or may not include mesopores in the silica wall forming the silica spheres. In one manufacturing method, various structural parameters of the pore-form silica The size of the pupil, the thickness of the silica wall, etc.) have not yet been developed.

As a result of efforts to develop a catalyst capable of solving the above-mentioned problems, the present inventors have completed the present invention by developing a simple and economical method for producing a hollow silica sphere.

Accordingly, it is an object of the present invention to provide a method for preparing a porous silica spherical silica spherical silica spherical silica spherical silica spherical silica spherical silica spherical silica spherical silica spherical silica spherical silica spherical silica spherical spherical silica spherical spherical silica And a pupil-shaped silica spheres produced by the method.

Another object of the present invention is to provide a method for manufacturing a spherical silica spherical catalyst capable of producing a spherical silica spheres in which metal nanoparticles are stably supported in a pore-type silica by incorporating metal particles required for forming a non- .

The object of the present invention is not limited to the above-mentioned objects, and although not explicitly mentioned, the object of the invention which can be recognized by a person skilled in the art from the description of the detailed description of the invention .

In order to accomplish the objects of the present invention described above, Forming a hollow spherical silica precursor including a hollow formed in the silica spheres through a solid phase conversion of the silica spheres and a shell layer formed to form outer walls of the pores; And a step of post-treating the pore-forming silica spherulite precursor.

In a preferred embodiment, the solid phase conversion is carried out by stirring the silica spheres in a basic aqueous solution in which the cyclic organic ammonium molecules are dissolved, followed by stirring to obtain a reaction solution; And a hydrothermal synthesis step of hydrothermally synthesizing the reaction solution to obtain the spherical silica spherule precursor.

In a preferred embodiment, in the stirring step, the cyclic organic ammonium molecules are bonded to the surface of the silica spheres by electromagnetic attraction to form a coating layer. In the hydrothermal synthesis step, the basic material contained in the basic aqueous solution And the inside of the silica spheres is melted to form a shell layer having a curved surface of a predetermined thickness and a hollow surrounded by the shell layer.

In a preferred embodiment, a plurality of pores are formed in the shell layer of the spherical silica spheres through the post-processing step.

In a preferred embodiment, the diameter of the pupil is determined according to the size of the silica spheres prepared in the step of preparing the silica spheres.

In a preferred embodiment, the preparation of the silica spheres is performed by synthesizing silica spheres so as to include the metal catalyst.

In a preferred embodiment, the post-treatment step is carried out by baking the spherical silica spheroid precursor at 500 ° C to 800 ° C.

In a preferred embodiment, the molar ratio of silica: metal salt: cyclic organic ammonium: water in the stirred reaction solution is 90 to 110: 16 to 50: 5 to 20: 5400 to 6600. Since the metal ion contained in the metal salt is based on an alkali metal monovalent, the molar ratio of the alkaline earth metal may be 8 to 25, which is 1/2 of the monovalent metal salt.

In a preferred embodiment, the thickness of the shell layer is controlled by adjusting the content of the cyclic organic ammonium.

The present invention also relates to an optical fiber comprising a hollow having a constant diameter; And a shell layer having a predetermined thickness constituting an outer wall of the pupil; Wherein the shell layer is composed of silica and cyclic organoammonium.

In a preferred embodiment, the silica and the cyclic organoammonium in the shell layer are included in a molar ratio of 90 to 110: 5 to 20.

The present invention also provides a hollow spherical silica spheres prepared by any one of the above-mentioned production methods, or a mesoporous shell layer formed by calcining the spherical silica spheroid precursor.

In a preferred embodiment, the mesoporosity is formed by removing the cyclic organic ammonium contained in the spherical silica spherule precursor.

The present invention also provides a method for preparing a silica spheres, comprising: preparing silica spheres containing metal particles to prepare silica spheres containing metal particles; Stirring the metal particle-containing silica spheres into a basic aqueous solution in which cyclic organic ammonium molecules are dissolved, followed by stirring to obtain a reaction solution; A hydrothermal synthesis step of hydrothermally synthesizing the reaction solution to obtain a porous spherical silica precursor containing metal particles, the hollow spherical particles comprising a hollow formed in the metal particle-containing silica spheres and a shell layer formed to form an outer wall of the pores; And a post-treatment step in which the metal particle-containing porous silica spheroid precursor is calcined at 500 ° C to 800 ° C.

In a preferred embodiment, in the stirring step, the cyclic organic ammonium molecules are bonded to the surface of the metal particle-containing silica spheres by electromagnetic attraction to form a coating layer. In the hydrothermal synthesis step, the basic substance contained in the basic aqueous solution A shell layer which is a curved surface composed of a surface of the silica spheres containing the metal particles and a coating layer and has a curved surface and a hollow surrounded by the shell layer are formed by penetrating into the coating layer and melting the interior of the silica spheres containing the metal particles, The metal particles are carried.

In a preferred embodiment, a plurality of pores are formed in the shell layer of the spherical silica spherical metal catalyst through the post-treatment step.

In a preferred embodiment, the diameter of the pore is determined according to the size of the metal particle-containing silica spheres prepared in the step of preparing the metal particle-containing silica spheres, and the content of the cyclic organic ammonium is controlled to adjust the thickness of the shell layer .

In a preferred embodiment, the molar ratio of silica: metal salt: cyclic organic ammonium: water in the stirred reaction solution is from 90 to 110: 3 to 23: 3 to 20: 5400 to 6600. Since the metal ion contained in the metal salt is based on an alkali metal monovalent, the molar ratio of the alkaline earth metal may be 8 to 25, which is 1/2 of the monovalent metal salt.

The present invention also relates to the above-mentioned pore-forming silica spheres; And a drug supported on the pores of the silica spheres.

According to the present invention described above, not only the non-porous silica spheres can be easily converted into the spherical silica spheres through a single synthesis step of solid phase transformation, but also the thickness of the shell layer of the spherical silica spheres and the diameter of the pores can be easily Can be controlled.

In addition, according to the present invention, it is possible to prepare a hollow silica spheres in which metal nanoparticles are stably supported on the inside of the hollow silica by incorporating metal particles necessary for forming the non-porous silica spheres, Can be manufactured.

These technical advantages of the present invention are not limited to the above-mentioned technical scope, and even if not explicitly mentioned, the effect of the invention which can be recognized by a person skilled in the art from the description of the concrete contents for carrying out the invention Of course.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing synthesis of a spherical silica spheres in the present invention and a process of controlling the thickness of a skin layer formed on the surface of the spheres. FIG.
2 is a transmission electron micrograph of a silica nanosphere having an average size controlled according to an embodiment of the present invention.
FIG. 3 is a transmission electron micrograph showing the effect of the cyclic organic ammonium molecules according to another embodiment of the present invention.
FIG. 4 is a graph showing a nitrogen adsorption isotherm and pore size distribution of a pore-type silica according to another embodiment of the present invention.
FIG. 5 is a transmission electron micrograph showing the result of synthesis according to the temperature change in the process of synthesizing the pore-forming silica according to the embodiments of the present invention.
FIG. 6 is a transmission electron microscope (SEM) image showing the result of synthesis according to pH change during the synthesis of the porous silica according to the embodiments of the present invention.
FIG. 7 is a transmission electron micrograph showing the result of synthesis of the porous silica according to the embodiments of the present invention with time.
FIG. 8 shows the result of ultraviolet-visible light spectroscopy analysis of the degree of release of the Rhodamine B molecules in the silica nanospheres and the pore-forming silica and release of the buffer solution, showing the degree of rhodamine absorption of the silica material.
FIG. 9 is a transmission electron micrograph of a silica nanosphere supporting platinum nanoparticles according to embodiments of the present invention. FIG.
FIG. 10 is a transmission electron microscope (SEM) image showing the result of synthesizing the platinum nanoparticle-loaded pore-type silica according to the temperature according to the embodiments of the present invention.
FIG. 11 is a transmission electron micrograph showing the result of synthesis according to pH change in the process of synthesizing the pore-type silica supporting platinum nanoparticles according to the embodiments of the present invention.
12 is a transmission electron micrograph showing the result of synthesis over time in the process of synthesizing the pore-form silica supporting the platinum nanoparticles according to the embodiments of the present invention.
13 is a transmission electron micrograph showing a change in the thickness of the silica shell according to the content of the cyclic organic ammonium molecules in the process of synthesizing the platinum nanoparticle-supported pore-type silica according to the embodiments of the present invention.
FIG. 14 is a scanning electron micrograph of the porous silica according to the content of the cyclic organic ammonium molecules in the process of synthesizing the platinum nanoparticle-supported pore-type silica according to the embodiments of the present invention.
15 is a scanning electron micrograph showing the change in size of platinum nanoparticles by carrying platinum nanoparticles on porous silica and mesoporous silica and then firing in a temperature range of 100 ° C to 600 ° C.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. Also, in certain cases, there may be a term selected arbitrarily by the applicant, in which case the meaning thereof will be described in detail in the description of the corresponding invention. Accordingly, the terms used in the present invention should not be construed to be mere terms, but should be interpreted based on the ordinary meanings of the terms and contents described throughout the specification of the present invention. In particular, where the use of the terms " about ", "substantially" or " about " is used, it can be interpreted that the manufacturing and material tolerances inherent in the stated meanings are used in the numerical value or in close proximity to the numerical value .

The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprising" or "having ", and the like, are intended to specify the presence of stated features, integers, steps, operations, elements, parts, or combinations thereof, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, parts, or combinations thereof.

The terms first, second, etc. may be used to describe various elements, but the elements should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

The term "Hollow " used in the present invention means a hollow space surrounded by outer walls in all directions.

As used herein, the term "sphere" means a sphere whose overall shape is a spherical body similar to a sphere or a sphere, and in particular, the "silica sphere"

The term "pore-forming silica spheres" used in the present invention means a structure in which a pore is formed in a silica spheres.

The term " solid phase conversion "used in the present invention means a reaction in which a pore is formed in the initial silica spheres while maintaining the external shape of the initial silica spheres as they are.

Hereinafter, the technical structure of the present invention will be described in detail with reference to the accompanying drawings and preferred embodiments.

However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Like reference numerals used to describe the present invention throughout the specification denote like elements.

The technical feature of the present invention is that the spherical silica spheres are formed by solid phase transformation in which spherical silica spheres having no pores inside are used as a starting material and pores are formed in a state in which the spherical outer shape is maintained, (hollow silica spheres).

That is, when a silica powder in the form of a solid powder is added to a basic aqueous solution and subjected to hydrothermal treatment, the silica constituting the silica spheres in a basic aqueous solution dissolves according to the heat treatment time and temperature and does not maintain its initial shape . Particularly, no pupil is formed inside. However, when the cyclic organic ammonium molecules are added to the basic aqueous solution as in the present invention, the cyclic organic ammonium molecules are bonded to the surface of the silica spheres by electrostatic attraction as shown in FIG. 1 to form a coating layer, In the hydrothermal synthesis reaction in the state, the coating layer is maintained and the metal salt such as sodium hydroxide (NaOH) of the basic aqueous solution penetrates into the inside of the silica spheres, and only the inside is melted to form the pores, .

Accordingly, the method of the present invention for preparing a hollow silica spheres comprises: preparing a silica spheres; Forming a hollow spherical silica precursor including a hollow formed in the silica spheres through a solid phase conversion of the silica spheres and a shell layer formed to form outer walls of the pores; And post-treating the pore-forming silica spherule precursor.

Particularly, the solid phase conversion is carried out by stirring the silica spheres in a basic aqueous solution in which the cyclic organic ammonium molecules are dissolved, followed by stirring to obtain a reaction solution obtained; And a hydrothermal synthesis step of hydrothermally synthesizing the reaction solution to obtain the spherical silica spherule precursor.

The silica spheres used in the present invention may have a diameter of several nanometers to several micrometers. The silica spheres used in the present invention can be uniformly synthesized in various sizes using the well-known Stöber method. Under the same conditions, , And silica particles containing metal particles in which metal nanoparticles are supported can be synthesized.

As the cyclic organic ammonium molecule, any known substance can be used. In addition to the benzene ring, alkyl and alkenyl groups can be applied in the molecule. In addition to the chlorine anion, anion for compensating the charge of ammonium is converted into various anions Can be utilized. One embodiment of the cyclic organic ammonium molecule may be used in the following form.

In one embodiment, as shown in FIG. 1, in a stirring step, a cyclic organic ammonium molecule is bonded to the surface of a silica spheres by electromagnetic attraction to form a coating layer. In the hydrothermal synthesis step, a basic substance contained in the basic aqueous solution is introduced into the coating layer And the inside of the silica spheres may be melted to form a hollow surrounded by a shell layer and a shell layer, which are curved surfaces of a certain thickness made up of the surface of the silica spheres and the coating layer.

As described above, the diameter of the pores formed in the finally obtained pore-type silica sphere is determined according to the size of the silica sphere as the starting material, that is, the size of the silica sphere prepared in the step of preparing the silica sphere, Since the thickness is determined, the size of the formed pores can be from several nm to several μm depending on the diameter of the silica spheres as the starting material, and the thickness of the shell layer can also be formed from several nanometers to tens of nanometers.

Therefore, according to the present invention, when the size of the pores having a required diameter is determined, it is possible to control the size of the pores very easily since the size of the silica spheres can be easily controlled when the silica spheres are prepared, and the cyclic organic ammonium content can be controlled The thickness of the skin layer can also be controlled very easily.

The molar ratio of silica: metal salt: cyclic organic ammonium: water in the reaction solution obtained in the stirring step may be 90 to 110: 16 to 50: 5 to 20: 5400 to 6600, 1 < / RTI > alkali metal, and it is possible to successfully obtain a pupil-type silica nanosphere in such a range of molar ratios. Accordingly, if the metal salt contains an alkaline earth metal which is divalent, the molar ratio may be 8-25, which is 1/2 of the monovalent metal salt. If the molar ratio of each component is less than or greater than the molar ratio of the respective components, it becomes difficult to obtain the desired pore-shape silica spheres through solid phase transformation. However, when the other composition variables (temperature and time) It is not necessary to confine the above range only as a successful molar ratio for obtaining a pupil-shaped silica nanosphere if other synthesis parameters (temperature and time) are different.

A number of pores are formed in the shell layer of the spherical silica spheres through a post-treatment step, and the pore size may include mesopores (pore size 2 to 50 nm). The post-treatment step can be carried out by calcining the spherical spherical silica precursor at 500 ° C to 800 ° C. The firing process is carried out using an electric heating device in the furnace, where various gases (such as oxygen, nitrogen or air) can be injected. In general, it is possible to treat by injecting air containing oxygen or oxygen, and in this process, the cyclic organic ammonium molecules contained in the spherical silica spherical precursor can be burned and removed.

In addition, the spherical silica spherule precursor of the present invention is obtained in the above-mentioned process for producing a spherical silica spheres, wherein a hollow having a constant diameter; And a shell layer having a predetermined thickness constituting an outer wall of the pupil; . Particularly, the porous spherical silica precursor of the present invention is characterized in that the shell layer is composed of silica and cyclic organic ammonium. In this case, the silica and the cyclic organic ammonium in the shell layer may be contained in a molar ratio of 90 to 110: 5 to 20.

In addition, the porous silica spheres of the present invention are produced by the above-described production method or manufactured by calcining the spherical silica spheroid precursor, so that the mesoporous shell layer is formed. Here, the mesoporosity is formed by removing the cyclic organic ammonium contained in the spherical silica spheres, so that the mesoporosity can be relatively uniformly formed as shown in FIG.

Next, a method for producing a spherical silica spherical metal catalyst of the present invention comprises: preparing silica spheres containing metal particles to prepare silica spheres containing metal particles; Stirring the metal particle-containing silica spheres into a basic aqueous solution in which cyclic organic ammonium molecules are dissolved, followed by stirring to obtain a reaction solution; A hydrothermal synthesis step of hydrothermally synthesizing the reaction solution to obtain a porous spherical silica precursor containing metal particles, the hollow spherical particles comprising a hollow formed in the metal particle-containing silica spheres and a shell layer formed to form an outer wall of the pores; And a post-treatment step in which the metal particle-containing pore-forming silica spherule precursor is calcined at 500 ° C to 800 ° C.

As shown in FIG. 1, in the stirring step, the cyclic organic ammonium molecules are bonded to the surface of the metal particle-containing silica spheres by electromagnetic attraction to form a coating layer. In the hydrothermal synthesis step, a basic substance The silica particles penetrating into the coating layer to melt the inside of the silica particles containing the metal particles to form a shell layer having a curved surface of a certain thickness and a coating layer made of the silica particles containing the metal particles and a hollow surrounded by the shell layer, So that the metal particles are supported. Here, the metal particles can be applied not only to the platinum nanoparticles of Experimental Examples to be described later, but also to various metal nanoparticles ranging from various transition metal nanoparticles to noble metal nanoparticles and mixed metal nanoparticles to which various elements are bound. It does not.

As described above, when the platinum nanoparticles are supported on the inside of the spherical silica spheres, the stability is much higher than that of the platinum nanoparticles carried on the surface of the silica spheres. Even though the platinum nanoparticles supported on the spherical silica spheres are kept completely unchanged in size and shape, the platinum nanoparticles carried on the spherical silica spheres are severely agglomerated to form an initial shape or size It is not retained and is transformed into a very large platinum lump. This may lead to a very rapid catalyst deactivation phenomenon, such as chlorination of methane which can utilize platinum nanoparticles as a catalyst.

Therefore, the spherical silica spherical metal catalyst of the present invention is useful in high temperature / high pressure catalytic chemical processes because the initial catalytic activity of the metal nanoparticles is maintained for a long time due to a decrease in aggregation of metal nanoparticles even in a high temperature / You can use it. In particular, it can be used as a catalyst with high activity / high number of times in the process of producing methyl chloride through the chlorination reaction of methane.

A number of pores are formed in the shell layer of the spherical silica spherical catalyst through a post-treatment step, and the pore size may include mesopores (pore size 2 to 50 nm). The post-treatment step may be carried out by firing the spherical porous silica spheres precursor containing the metal particles at 500 ° C to 800 ° C in the same manner as in the above-mentioned method of producing the hollow silica spheres.

The diameter of the pore may be determined according to the size of the silica particle containing metal particles prepared in the step of preparing the metal particle-containing silica spheres, and the thickness of the shell layer may be controlled by controlling the content of the cyclic organic ammonium.

Meanwhile, in the reaction solution obtained in the stirring step, the molar ratio of silica: metal salt: cyclic organic ammonium: water may be 90 to 110: 6 to 46: 3 to 20: 5400 to 6600, 1 < / RTI > alkali metal, and it is possible to successfully obtain a pupil-type silica nanosphere in such a range of molar ratios. Accordingly, when the metal salt includes an alkali earth metal which is divalent, the molar ratio may be 3 to 23, which is 1/2. This range is determined experimentally through a number of experiments. In this range of mole ratios, pupil-shaped silica nanospheres can be successfully obtained. If the molar ratio of each component is less than or greater than the molar ratio of the respective components, it becomes difficult to obtain the desired pore-shape silica spheres through solid phase transformation. However, when the other composition variables (temperature and time) It is not necessary to limit the above range to a successful molar ratio for obtaining a pupil-shaped silica nanosphere. However, unlike the reaction solution obtained by the method of preparing the pore-forming silica spheres, the inclusion of metal particles further led to the formation of the pores at lower pH.

Further, the drug storage material of the present invention is a drug storage material loaded with the drug in the pores of a pore-shaped silica spheres obtained by the above-mentioned production method. Since the shell layer of the spherical silica spheres has mesopores, It can be used as a drug delivery vehicle because it can store macromolecules such as medicinal substances and release them.

Example 1

1. Preparation of silica spheres

Non-porous silica spheres were synthesized as follows. After dissolving 19.2 ml of ammonia water in 900 ml of ethanol, stir at room temperature for 5 minutes. To this solution, 30 ml of tetraethoxyorthosilicate is added and the mixture is stirred at room temperature for 1 day. The product is separated through a centrifuge and washed several times with ethanol. The obtained product was dried at 60 ° C. to synthesize silica nanospheres having a size of 100 nm. Here, purchased from the tetraethoxy ortho silicate _{(Si (OC 2 H 5)} 4) is a product of Sigma-Aldrich (Sigma Aldrich), ethanol (C ₂ H ₅ OH), ammonia water (NH ₄ OH) is vena (Daejung, Korea) Respectively. All reaction reagents were used without further purification and the solvent was adjusted by adjusting the amount of ammonia water and ethanol.

2. Formation of a pupil-shaped silica nanocomposite

A cyclic organic ammonium molecule (CDM) was synthesized and used to convert the silica nanospheres into a spherical silica spherical precursor through solid phase conversion. Sodium hydroxide (2NaOH = Na ₂ O) was purchased from Daejung, Korea, and distilled water was used as a solvent.

① Stirring stage

0.868 g of cyclic organic ammonium molecules and 0.46 g of sodium hydroxide were dissolved in 27 g of distilled water and stirred at room temperature for about 10 minutes to obtain a reaction solution. Here, the molar ratio of the reaction solution was SiO ₂ : Na ₂ O: CDM: H ₂ O = 100: 23: 10: 6000.

③ Hydrothermal synthesis step

1.5 g of the prepared silica nanorods was added to the reaction solution, and the mixture was stirred at room temperature for 1 hour. Then, the reaction solution was transferred to a stainless autoclave and heated at 130 ° C for 18 hours for hydrothermal synthesis.

③ Separation step

After cooling the autoclave to room temperature, the resultant spherical spherical silica precursor was separated through a centrifuge, washed several times with distilled water, and dried at 100 DEG C to obtain a spherical silica spherule precursor.

3. Post-processing step

The shell layer constituting the outer wall of the pupil in the obtained spherical silica spherical precursor contains silica and cyclic organic ammonium molecules. Therefore, when the cyclic organic ammonium molecules are removed from the shell layer, pores can be easily introduced into the shell layer to produce a hollow silica spheres having a mesoporous shell layer.

Specifically, 0.5 g of the obtained spherical porous silica precursor was placed in a plastic furnace and heated at 550 캜 for 4 hours to carry out a post-treatment step to prepare a spherical silica spherule 1 (100 nm).

Example 2

In order to obtain silica spheres having a size of 200 nm in preparation of the silica spheres, the same procedure as in Example 1 was carried out except that 42 ml of ammonia water was dissolved in 882 ml of ethanol and then stirred at room temperature for 5 minutes. 200 nm).

Example 3

Silica spheres having a diameter of 300 nm were prepared in the same manner as in Example 1 except that the silica spheres were dissolved in 124 ml of ammonia water and 816 ml of ethanol to obtain silica spheres having a size of 300 nm, ).

Comparative Example 1

The comparative silica material 1 was obtained in the same manner as in Example 1, except that the experiment was carried out without adding the cyclic organic ammonium molecules in the reaction solution in Example 1. The molar ratio of the reaction solution is 100SiO _2: 23Na ₂ O: O ₂ is 6000H.

Comparative Example 2

The comparative silica material 2 was obtained in the same manner as in Example 1 except that the reaction temperature was adjusted to 100 ° C instead of 130 ° C.

Experimental Example 1

The size of the silica spheres obtained in Example 1 to Example 3 was confirmed by a transmission electron microscope and the results are shown in Fig. As shown in FIG. 2, the sizes of the silica spheres obtained in Examples 1 to 3 were confirmed to be 100 nm, 200 nm, and 300 nm, respectively, by a transmission electron microscope photograph.

Experimental Example 2

In order to confirm the role of the cyclic organic ammonium molecule in the solid phase conversion of the silica spheres, the hollow silica spheres 1 obtained in Example 1 and the silica silica materials 1 obtained in Comparative Example 1 were observed with a transmission electron microscope, 3.

It can be seen from the transmission electron microscope image shown in FIG. 3 that the presence of the cyclic organic ammonium molecule can form a hole in the silica spheres. That is, only the cyclic organic ammonium molecules were added in Example 1 and not in Comparative Example 1, although Example 1 and Comparative Example 1 all had the same reaction conditions, Type silica spheres were obtained, but in Comparative Example 1, a silica material having no pores formed in the silica was obtained.

Experimental Example 3

The nitrogen adsorption isotherm of the spherical silica spheres 1 obtained in Example 2 was observed and the results are shown in Fig.

It can be seen that pores exist in the spherical silica spheres 1 synthesized through the graph shown in FIG. 4, and the skeleton forming the shell layer of the spherical silica spheres has a porous structure. At this time, it was confirmed that the surface area of one shell layer of the porous silica spheres was 55 m ² / g, and the volume of the pores existing inside the shell layer was 0.38 cm ³ / g.

Experimental Example 4

In order to confirm the effect of the hydrothermal synthesis temperature in the solid phase conversion of the silica spheres, the pore-form silica spheres 2 obtained in Example 2 and the comparative silica material 2 obtained in Comparative Example 2 were observed with a transmission electron microscope, Respectively.

From FIG. 5, it can be seen that when the temperature is relatively low, 100 DEG C, the silica spheres are not formed well in the silica spheres and the silica spheres appear to be collapsed. When the temperature exceeds 100 DEG C during the hydrothermal synthesis reaction, As shown in Fig. Therefore, in the method of preparing the hollow silica spheres according to the present invention, the temperature of the hydrothermal synthesis step is higher than at least 100 ° C., and although not described in the experimental example, if the hydrothermal synthesis temperature is higher than 130 ° C., there is no significant difference in the pore formation.

Experimental Example 5

In order to confirm whether the pH of the reaction solution influences the pore formation of the silica spheres in the hydrothermal synthesis step, the result obtained by controlling the amount of sodium hydroxide in the composition of the reaction solution in the hydrothermal synthesis step was observed with a transmission electron microscope, 6. The molar ratio of the reaction solution during the hydrothermal synthesis was SiO ₂ : Na ₂ O: CDM: H ₂ O 100: x: 10: 6000 (x = 5.75, 6.5, 7, 7.5, 30).

From FIG. 6, it can be seen that when the pH is low, the pores do not form inside the silica spheres but maintain the silica spheres shape, but when the pH is high, the pores are formed but the silica spheres are collapsed, It can be confirmed that it is reassembled in the form of

Experimental Example 6

In order to confirm whether the hydrothermal synthesis time affects the pore formation in the silica spheres in the hydrothermal synthesis step, the result obtained by controlling the hydrothermal synthesis time in the hydrothermal synthesis step to 18, 30, 48, 96 hours respectively was observed with a transmission electron microscope The photograph is shown in Fig. The molar ratio of the reaction solution during the hydrothermal synthesis was SiO ₂ : Na ₂ O: CDM: H ₂ O = 100: 7: 10: 6000.

From FIG. 7, it can be seen that as the hydrothermal synthesis time increases, the pores formed in the silica spheres are further reduced. Particularly, the reaction solution had a low molar ratio of SiO ₂ : Na ₂ O: CDM: H ₂ O of 100: 7: 10: 6000 and the pH of the reaction solution was low. I could confirm. That is, the pupil was not formed in the case of 18 hours but the pupil was formed in 96 hours.

Example 4

0.05 g of the spherical silica spheres 2 obtained in Example 2 was added to 5 ml of a rhodamine solution (2.4 mg / ml) and stirred for 2 days to prepare a drug reservoir loaded with rhodamine in the cavity of the spherical silica spherule 2. Separate the drug reservoir through a centrifuge and wash several times with distilled water. The resulting drug storage was dried in a 35 ^o C vacuum oven for 1 day and then recovered. Here, in order to confirm the storage ability of the spherical silica spheres, a rhodamine B molecule having a molecular structure similar to that of a drug substance was used instead of the actual medicinal substance.

Comparative Example 3

A comparative storage material was obtained by carrying out the same method as in Example 4, except that the silica spheres other than the spherical silica spheres 2 were used.

Experimental Example 7

In order to confirm the possibility of the spherical silica spheres as a drug substance storage material, the drug storage material obtained in Example 4 and the comparative storage material obtained in Comparative Example 3 were compared and analyzed as follows.

0.01 g of the drug storage material obtained in Example 4 and the comparative storage material obtained in Comparative Example 3 were added to 17.5 ml of a buffer solution (pH = 6.9) and stirred at room temperature. The buffer solution is sampled over time and the solid silica material is separated using a filter syringe to obtain a pure solution. The pure solution thus obtained was analyzed by ultraviolet spectroscopy to calculate the amount of rhodamine discharged from the drug storage and the comparative storage, respectively, and the results are shown in FIG.

 From Fig. 8, the solution used in the analysis was released from the drug reservoir (the drug absorbed in the spherical silica spheres) and the comparative sample (the drug absorbed in the silica spheres) on the drug rhodamine buffer solution, It was confirmed from the graph that a larger amount of rhodamine was detected. Since the drug storage material of the present invention uses a pore-type silica sphere, there is more internal space than the comparative example using silica nano-spheres, And that it could absorb a positive rhodamine.

Example 5

1. Preparation of silica spheres containing metal particles

① Synthesis of platinum nanoparticles to be supported on a spherical silica spheres

0.222 g of polyvinylpyrrolidone was dissolved in 10 ml of ethylene glycol, followed by stirring at room temperature. At the same time, 0.04 g of chloroplatinic acid is dissolved in 10 ml of ethylene glycol. After stirring at room temperature, the two solutions are mixed, and then helium is stirred at room temperature until the solution is dissolved. The container containing the solution is placed in an oil bath heated to 180 ^° C and stirred for 1 hour. The vessel is cooled to room temperature and acetone is used to submerge the platinum nanoparticles. The solution is separated through a centrifuge, and the resulting platinum nanoparticles are stored in an ethanol solution (1 mg / ml). Here, polyvinylpyrrolidone ((C ₆ H ₉ NO) _n ), chloroplatinic acid (H ₂ PtCl ₆ O ₆ H ₂ O), and ethylene glycol ((CH ₂ OH) ₂ ) were purchased from Sigma Aldrich Respectively. All reagents were used without further purification.

② Silicon spheres containing metal particles

21 ml of ammonia water and 10 ml of platinum solution are dissolved in 431 ml of ethanol and stirred at room temperature for 5 minutes. To this solution, 15 ml of tetraethoxyorthosilicate is added and the mixture is stirred at room temperature for 1 day. The product is separated through a centrifuge and washed several times with ethanol. The obtained product was dried at 60 ^° C to synthesize a metal-containing silica spheres carrying platinum nanoparticles formed by coating silica around platinum nanoparticles.

2. Stirring step

0.868 g of cyclic organic ammonium molecules (CDM) and 0.115 g of sodium hydroxide were dissolved in 27 g of distilled water, and the mixture was stirred at room temperature for about 10 minutes to obtain a reaction solution. Here, the molar ratio of the reaction solution was SiO ₂ : Na ₂ O: CDM: H ₂ O = 100: 5.75: 10: 6000.

3. Hydrothermal synthesis step

1.5 g of the prepared metal-containing silica sphere was added to the reaction solution, and the mixture was stirred at room temperature for 1 hour. Then, the reaction solution was transferred to an autoclave of stainless steel and placed at 130 ° C for 18 hours for hydrothermal synthesis.

After cooling the autoclave to room temperature, the precursor of the porous silica spheres containing metal particles carrying the obtained platinum nanoparticles was separated through a centrifugal separator, washed several times with distilled water, and dried at 100 ° C to remove metal Containing spherical silica spherule precursor.

4. Post-processing step

The shell layer constituting the outer wall of the pupil in the obtained spherical porous silica spheres containing the metal particles contains silica and cyclic organic ammonium molecules. Therefore, when the cyclic organic ammonium molecules are removed from the shell layer, a pore-form silica spherical catalyst having a structure in which pores are easily introduced into the shell layer to have a mesoporous shell layer and a metal particle catalyst exists in the pores have.

Specifically, 0.5 g of the obtained spherical porous silica spherical precursor was placed in a sintered furnace and heated at 550 캜 for 4 hours to carry out a post-treatment step to prepare a spherical silica spherical metal catalyst 1 (10 CDM).

Example 6

Except that 0.434 g of cyclic organic ammonium molecule (CDM) was added to the reaction solution in the stirring step and the molar ratio of the reaction solution was SiO ₂ : Na ₂ O: CDM: H ₂ O = 100: 5.75: 5: 6000 The procedure of Example 5 was followed to prepare a spherical silica spherical metal catalyst 2 (5 CDM).

Example 7

1.302 g of cyclic organic ammonium molecule (CDM) was added to the reaction solution in the stirring step, except that the molar ratio of the reaction solution was SiO ₂ : Na ₂ O: CDM: H ₂ O = 100: 5.75: 15: 6000 The procedure of Example 5 was followed to prepare a spherical silica spherical metal catalyst 3 (15 CDM).

Comparative Example 5

The same procedure as in Example 5 was carried out except that the reaction temperature was adjusted to 100 ° C instead of 130 ° C to obtain a comparative metal catalyst 1.

Comparative Example 6

0.1 g of SBA-15, a mesoporous silica material, was impregnated with a platinum solution having the same content as that used in the preparation of the spherical silica spherical metal catalyst 1. Ethanol was added and stirred until the solution was immersed. The solvent was evaporated using a rotary evaporator to obtain a comparative metal catalyst 2.

Experimental Example 8

The morphology and size of the hollow spherical silica spherical catalyst 1 obtained in Example 5 were confirmed by transmission electron microscope and the results are shown in FIG.

As shown in FIG. 9, it was confirmed that the spherical silica spherical metal catalyst 1 obtained in Example 5 had platinum particles supported therein and existed in a Core @ Shell structure, and the size was 70 nm.

Experimental Example 9

In order to confirm the effect of the hydrothermal synthesis temperature on the solid phase conversion of the metal-containing silica spheres for producing the spherical silica spherical metal catalyst, the spherical silica spherical metal catalyst 1 obtained in Example 5 and the comparative example metal The catalyst 1 was observed with a transmission electron microscope and the result thereof is shown in Fig.

It can be seen from Fig. 10 that the shell of the spherical silica spheres carrying the platinum nanoparticles is not uniform and appears to have a less hollow interior. This shows that, at a relatively low temperature of 100 ° C, the same results as those of Experimental Example 4 were obtained in which it was confirmed that the pores were not formed well in the metal-containing silica spheres but the silica spheres appeared to be collapsed. Therefore, even when a metal-containing silica sphere is used instead of a silica sphere, it can be seen that a pore is formed inside the silica sphere when the temperature exceeds 100 ° C during the hydrothermal synthesis reaction.

Experimental Example 10

In order to confirm whether the pH of the reaction solution influences the pore formation of the metal-containing silica spheres and the loading of the metal particles in the hydrothermal synthesis step for producing the spherical silica spherical metal catalyst, the amount of sodium hydroxide in the composition of the reaction solution And the resultant was observed with a transmission electron microscope. The resulting photograph is shown in Fig. The molar ratio of the reaction solution in the hydrothermal synthesis was SiO ₂ : Na ₂ O: CDM: H ₂ O 100: x: 10: 6000 (x = 5.75, 11.5, 23).

From Fig. 11, it can be seen that when the pH is high, silica nanowires carrying platinum nanoparticles collapse and the silica material melts out to obtain a pore-forming silica spherical catalyst carrying platinum nanoparticles. It was confirmed that when the pH was relatively low, the silica material was not dissolved in the silica nanoparticles loaded with the platinum nanoparticles but the pore-form silica carrying the platinum nanoparticles was obtained.

Experimental Example 11

In order to investigate the effect of hydrothermal synthesis time on the pore formation of silica spheres in the hydrothermal synthesis step for preparing spherical silica spherical catalysts, hydrothermal synthesis time was adjusted to 6, 18 and 36 hours in the hydrothermal synthesis step, And observed with a transmission electron microscope. The resulting photograph is shown in Fig. The molar ratio of the reaction solution during the hydrothermal synthesis was SiO ₂ : Na ₂ O: CDM: H ₂ O = 100: 5.75: 10: 6000.

It can be seen from Fig. 12 that as the hydrothermal synthesis time increases, the interior of the pore-form silica spheres carrying the platinum nanoparticles is further reduced.

Experimental Example 12

In order to investigate the change of the thickness of the shell layer which forms the wall of the pupil depending on the content of the cyclic organic ammonium molecule in the solid phase conversion process of the metal containing silica spheres for preparing the spherical silica spherical catalyst, The pore-form silica spherical metal catalysts 1 to 3 obtained by varying the content of ammonium molecules were observed with a transmission electron microscope, and the photographs thereof are shown in Fig. Further, the spherical silica spherical metal catalysts 1 to 3 were observed under a scanning microscope, and the photographs thereof are shown in Fig.

As the amount of cyclic organic ammonium molecules (CDM) increases, the peel thicknesses of the porous silica spherical metal catalysts 2, 1 and 3 carrying the platinum nanoparticles are 16.2 nm and 21.7 nm, respectively, nm and 27.8 nm, respectively. These experimental results show that the thickness of the shell layer of the spherical silica spheres can be controlled by controlling the content of the cyclic organic ammonium molecules.

Also, from FIG. 14, it was confirmed that even if the content of the cyclic organic ammonium molecules was increased, the shape outside the shell layer was not affected.

Experimental Example 13

Experiments were carried out to confirm the change in size of the platinum nanoparticles according to the firing temperature, which is shown in FIG.

As shown in FIG. 15, platinum nanoparticles were confirmed by scanning electron microscope photographs. As a result, in the case of mesoporous silica of Comparative Example 2, the size of the platinum nanoparticles As shown in FIG. On the other hand, it was confirmed that the size of the platinum nanoparticles supported in the pore-type silica spheres of the pore-type silica spherical metal catalyst 1 did not change even though the temperature was increased.

It can be predicted that when the platinum nanoparticles are supported in the pores of the pore-type silica spheres of the present invention, the relative heat does not greatly affect the metal particles.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, Various changes and modifications will be possible.

Claims (19)

Preparing a silica spheres;
Forming a hollow spherical silica precursor including a hollow formed in the silica spheres through a solid phase conversion of the silica spheres and a shell layer formed to form outer walls of the pores; And
And then post-treating the spherical silica spherulite precursor.
The method according to claim 1,
Wherein the solid phase conversion is carried out by adding the silica spheres to a basic aqueous solution in which cyclic organic ammonium molecules are dissolved and then stirring to obtain a reaction solution obtained; And a hydrothermal synthesis step of hydrothermally synthesizing the reaction solution to obtain the spherical silica spherule precursor.
3. The method of claim 2,
In the stirring step, the cyclic organic ammonium molecules are bonded to the surface of the silica spheres by electromagnetic attraction to form a coating layer,
In the hydrothermal synthesis step, a basic substance contained in the basic aqueous solution penetrates into the coating layer to melt the inside of the silica spheres, thereby forming a skin layer having a curved surface of a predetermined thickness, which is composed of the surface and the coating layer of the silica spheres, ) Is formed on the surface of the porous silica powder.
The method according to claim 1,
Wherein a plurality of pores are formed in the shell layer of the spherical silica spheres through the post-processing step.
The method according to claim 1,
Wherein the diameter of the pore is determined according to the size of the silica spheres prepared in the step of preparing the silica spheres.
The method according to claim 1,
Wherein the step of preparing the silica spheres is performed by synthesizing silica spheres so as to include a metal catalyst.
7. The method according to any one of claims 1 to 6,
Wherein the post-treatment step is carried out by firing the pore-forming spherical silica precursor at 500 ° C to 800 ° C.
The method according to claim 2 or 3,
Wherein the molar ratio of the silica: metal salt (based on the monovalent metal ion) to the cyclic organic ammonium: water in the stirred reaction solution is 90 to 110: 16 to 50: 5 to 20: 5400 to 6600 Way.
9. The method of claim 8,
Wherein the thickness of the shell layer is controlled by controlling the content of the cyclic organic ammonium.
A hollow of constant diameter; And a shell layer having a predetermined thickness constituting an outer wall of the pupil; However,
Wherein the shell layer comprises silica and cyclic organoammonium.
11. The method of claim 10,
Wherein the silica and the cyclic organic ammonium in the shell layer are contained in a molar ratio of 90 to 110: 5 to 20.
A spherical silica spheres prepared by the production method of any one of claims 1 to 6, or a mesoporous silica shell prepared by calcining the spherical silica spheroid precursor of claim 10.
13. The method of claim 12,
Wherein the mesoporosity is formed by removing the cyclic organic ammonium contained in the spherical silica spherule precursor.
Preparing a silica spheres containing metal particles to prepare silica spheres containing metal particles;
Stirring the metal particle-containing silica spheres into a basic aqueous solution in which cyclic organic ammonium molecules are dissolved, followed by stirring to obtain a reaction solution;
A hydrothermal synthesis step of hydrothermally synthesizing the reaction solution to obtain a porous spherical silica precursor containing metal particles, the hollow spherical particles comprising a hollow formed in the metal particle-containing silica sphere and a shell layer formed to form an outer wall of the pore; And
And a post-treatment step of calcining the spherical porous silica spheroid precursor containing the metal particles at 500 ° C to 800 ° C.
15. The method of claim 14,
In the stirring step, the cyclic organic ammonium molecules are bonded to the surface of the metal particle-containing silica spheres by electromagnetic attraction to form a coating layer,
The basic substance contained in the basic aqueous solution penetrates into the coating layer to melt the inside of the silica particle containing metal particles to form a skin layer having a curved surface of a certain thickness and composed of a surface of the silica particle containing the metal particle and a coating layer, Wherein a hollow is formed in the pore-shaped silica spherical catalyst layer, and the metal particles are supported on the pores formed.
15. The method of claim 14,
Wherein a plurality of pores are formed in the shell layer of the spherical silica spherical catalyst through the post-treatment step.
15. The method of claim 14,
Wherein the diameter of the pores is determined according to the size of the silica spheres containing the metal particles prepared in the step of preparing the silica spheres containing the metal particles and the thickness of the shell layer is controlled by controlling the content of the cyclic organic ammonium Process for preparing spherical silica spherical metal catalysts.
18. The method according to any one of claims 14 to 17,
Wherein the molar ratio of the silica: metal salt (based on the monovalent metal ion) to the cyclic organic ammonium: water in the stirred reaction solution is 90 to 110: 6 to 46: 3 to 20: 5400 to 6600, Catalyst.
A spherical silica spheres of claim 12; And
And a drug supported on the pores of the silica spheres.

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