KR20020094692A - Preparation of silica and silica-polystyrene sturctures using various interfaces - Google Patents

Abstract

PURPOSE: A method for manufacturing silica structures by selectively forming silica on interfaces produced between solid and gas, liquid and liquid, and liquid and solid using amphiphilic alkoxy silane as a precursor is provided. CONSTITUTION: The manufacturing method of silica structures is characterized in that the silica structures are manufactured by forming silica on interfaces of gas-liquid, liquid-liquid and liquid-solid using a biphilic silica precursor under the arbitrary pH condition of 2 to 12 without artificial condition change, wherein the biphilic silica precursor is tetrakis(2-(2-methoxyethoxy)ethoxy)silane or tetrakis(2-methoxyethoxy)silane, the silica structures are manufactured by using surfactant such as cetyltetramethylammonium bromide, Span, Tween, dihexadecyl dimethyl ammonium bromide and didodecyl dimethyl ammonium bromide in preparation of the gas-liquid interface, and leaving the surfactant alone at the temperature range of 10 to 200 deg.C, and the silica structures are manufactured by using surfactant such as cetyltetramethylammonium bromide, Span, Tween, dihexadecyl dimethyl ammonium bromide, didodecyl dimethyl ammonium bromide, dioleoylphosphatidylethanol amine, dioleoylglycero phosphocholine, dioleoylglycero phosphoglycerol sodium, phosphatidylethanol amine such as dioleoyltrimethylammonium propane, phosphocholine, glycerol salts and tetraammonium bromide in preparation of the liquid-liquid interface, and leaving the surfactant alone at the temperature range of 10 to 50 deg.C.

Description

Preparation of silica and silica-polystyrene sturctures using various interfaces

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for preparing silica structures at various interfaces, wherein silica is selectively formed at the interface between solid-gas, liquid-liquid, and liquid-solid, using an amphiphilic alkoxy silane as a precursor. It is a technique of obtaining a silica structure by making it.

A similar method of obtaining a silica structure is a sol-gel method. In this case, tetraethoxy silane, tetradramethoxy silane, and the like are hydrolyzed at a predetermined pH to obtain a sol, and then the silica is mainly gelled by changing the pH. Get a structure. Therefore, in order to inject tetraethoxy silane, tetramethoxy silane and the like directly into the reaction system to generate silica at the interface, sol is formed from these precursors by maintaining a low or high pH so that these precursors can be hydrolyzed. In other words, the gel is changed by changing the pH, and in most cases, rather than obtaining an individual structure, a collective structure in which spheres or tubes share walls is obtained. Examples of individual silica spheres obtained by dissolving tetramethoxy silane, tetraethoxy silane, or tetrabutoxy silane in toluene and stabilizing with cetyltrimethylammonium bromide while maintaining the external pH at 2 were continuously stirred. (Schacht et al., Science, 273, 768-771, 1996), examples of obtaining individual silica tubes include 1,2-bis (10,12-tricosadiinoyl) -sn-glycero- between pH 8.2 and 8.4. A separately prepared silica sol was added to the tube obtained using 3-phosphocholine to adsorb to the surface for 6-9 days (Barel and Schoen, Chemistry of Materials, 5 (2), 145-147, 1993), or cholesterol Tetraethoxy silane or tetramethoxy silane is also added to the mixture containing the group-containing gel-forming molecules, and the pH is properly maintained to form a fiber-shaped composite surrounded by silica. There is for example, a war eoteonaen tube (Jung, etc., Langmuir, 16, 1643-1649, 2000). All of these methods react sensitively to the reaction conditions, and there is a limitation in the type of skeleton used. The former method of making silica spheres has not only been found to be possible at pH 2 or below, but also requires continuous stirring of the reaction system, spheres are obtained only at certain stirring rates, and the other two methods of making tubes are sol first. By using this, the reaction time is long, there are large sol particles on the surface, and in the latter method, the sol is formed first and cooperatively arranges with the molecules causing gelation, and gelation occurs. It is different from the contents of the present invention because it is a method of obtaining a filled silica fiber form and burning it to form a tube.

In addition, there is an example of preparing a silica nanotube using a surfactant (Haradaand Adachi, Advanced Materials, 12, 839-841, 2000). In this case, a gel containing nanotubes was obtained instead of an individual tube. It is completely different from the properties, and a study shows that reaction of tetraethoxy silane in a mixture of ethanol, ammonia, water and DL-tartaric acid yields a small amount of silica nanotubes (Nakamura and Matsui, Advanced Materials, 7 (10)). , 871-872, 1995, but is also quite different from the context of the present invention.

In the present invention, individual spheres and tubes of various sizes, walled with silica and silica-polystyrene, are produced in a much simpler, more gentle and wider range of pH and temperature ranges than other technologies. A variety of sensitive active substances, as well as living microorganisms, can be introduced into silica spheres very easily without deterioration.

The present invention uses tetrakis (2- (2-methoxyethoxy) ethoxy) silane and tetrakis (2-methoxyethoxy) silane, which are amphoteric affinity silane compounds, as silica precursors. It is characterized by obtaining a silica structure formed in the form of an interface by using a phenomenon in which silica is selectively generated at an interface formed between a liquid and a liquid-solid. In the present invention, a thicker silica wall is prepared using a mixture of the amphoteric silane compound and a hydrophobic silane compound, tetraethoxy silane, tetramethoxy silane and trimethylvinyl silane, as a silica precursor. As the gas-liquid interface, a homogenizer or ultrasonic solution containing 1-10% by weight of a surfactant such as cetyltetramethylammonium bromide, Span, Tween, dihexadecyldimethylammonium bromide, and didodecyldimethylammonium bromide The wall of foam generated by treatment with a generator is used, and water for dissolving the surfactant uses distilled water, tap water, and a phosphate buffer having a pH of 6 to 12 adjusted to any value between 2 and 12. Bubbles are produced in enclosed spaces filled with air, nitrogen, oxygen, helium, argon, etc. to determine the type of gas entering the bubbles.

The liquid-liquid interface is a mixture of water and hydrophobic oils (toluene, benzene, hexane, mineral oil, cooking oil, chlorobenzene, cresol, styrene monomer, methyl methacrylate, methyl acrylate, thiophene, perperyl alcohol oligomer, etc.). Obtained by vigorous stirring without a surfactant or in the presence of the surfactant, dioleoylphosphatidylethanolamine, dioleoylglycerophosphocholine, dioleoylglycerophosphoglycerol sodium salt, dioleoyltrimethylammonium propane Neutral, negative, and positive lipids, such as phosphakidylethanolamine, phosphocholine, glycerol salt, and tetraammonium bromide, are obtained using the same method. In the case of using lipids, an interface between water and water between the lipids is created. When preparing the interface between water and hydrophobic oils, depending on the relative amounts of the two phases, either a mixture of oil defenses in water (normal emulsion) or a mixture of water droplets in oil (reverse phase emulsion) is obtained. The water layer used at this time is the same as the water layer used for obtaining the gas-liquid interface.

The interface between a solid and a liquid is obtained by dispersing a tube obtained by crystallizing 1,2-bis (10,12-tricosadiinoyl) -sn-glycero-3-phosphocholine in ethanol in the above water layer.

5-40% by volume of tetrakis (2- (2-methoxyethoxy) ethoxy) silane or 5-20% by volume of the phase containing the lesser amount in the mixture having the interface obtained as described above. Tetrakis (2-methoxyethoxy) silane was added and left to obtain a silica structure. When the liquid-liquid interface composed of water-oil is obtained using a surfactant, the reaction temperature is performed between 10 and 200 degrees Celsius, and 1 when the liquid-liquid interface composed of water-water prepared using lipid is used. In turn, the reaction takes place between 10 and 50 degrees Celsius and then aged between 50 and 200 degrees to give a harder silica structure.

Toluene containing polystyrene at a concentration of 3-20% by weight in a hydrophobic oil phase results in the formation of hollow spheres formed from silica-polystyrene walls that do not deform even when dried in air.

When monomers such as styrene monomer, methyl methacrylate and methyl acrylate are added together with benzoyl peroxide and AIBN, and the obtained silica sphere is heated in an oven between 70-150 degrees Celsius, radical polymerization takes place internally to cause polystyrene, poly ( Methyl methacrylate), poly (methyl acrylate) and the like contain a silica sphere.

This invention will be described in more detail based on the following examples. However, the present invention is not limited to these examples.

Example 1

Prepare a 3% by weight solution of cetyltetramethylammonium quenbromide with distilled water at pH 5.5 and mix 5 mL of this solution and 1 mL of toluene by hand, use a homogenizer, or mix using an ultrasonic generator. The toluene particles obtained have diameters of approximately 30 micrometers, 500 nanometers and 100 nanometers, respectively. To the mixture, 100 microliters and 50 microliters of tetrakis (2- (2-methoxyethoxy) ethoxy) silane or tetrikis (2-methoxyethoxy) silane were added and allowed to stand at room temperature with gentle stirring. The silica spheres containing toluene can be obtained which can be observed under a microscope within 4 hours.

Example 2

Mix 0.5 mL of toluene with 5 mL of distilled water adjusted to pH 7 using NaOH and shake by hand to produce toluene droplets. Add 100 microliters of tetrakis (2- (2-methoxyethoxy) ethoxy) silane and shake it vigorously by hand until no phase separation occurs. Phase separation does not occur after about 40 minutes and the formation of the silica shell covering the toluene is confirmed under a microscope.

Example 3

After culturing Pseudomonas oleoboranes, the cells obtained by centrifugation are spread again in water, and 1 mL of this mixture is poured into 5 mL of olive oil and stirred vigorously. 50 microliters of tetrakis (2- (2-methoxyethoxy) ethoxy) silane was added to the mixture and slowly stirred at room temperature. After about 40 minutes, the silica shell formed between water and olive oil was identified. Observe the microorganisms in action.

Example 4

1 mL of styrene monomer and 100 mg of benzoyl peroxide are uniformly mixed, and 3% aqueous solution of cetyltrimethylammonium bromide is added thereto, followed by generation of particles using a homogenizer, followed by tetrakis (2-methoxyethoxy) silane. Add 100 microliters and leave for 4 hours. Silica spheres containing the obtained styrene monomer were placed in an oven maintained at 70 degrees Celsius and cooled after 6 hours to produce hard spheres having polystyrene formed therein.

Example 5

Toluene saturated with Sudan III was used to make a 5% polystyrene solution, 1 mL of this solution was mixed with 5 mL of 3% cetyltrimethylbromide, prepared with pH 7.4 phosphate buffer, stirred with a homogenizer and tetrakis (2 Adding 100 microliters of -methoxyethoxy) silane immediately forms silica spheres (within 4 seconds) which dry in air to yield silica-polystyrene hybrid spheres coated with the red color of means III.

Example 6

A mixture containing 5 mL of toluene, 50 mg of dihexateyldimethylammonium bromide, and 1 mL of distilled water was vigorously stirred with a homogenizer, and 50 microliters of tetrakis (2-methoxyethoxy) silane was added thereto, followed by about 2 hours. Leave it. To this was added 50 microliters of tetrakis (2-methoxyethoxy) silane again and left for about 2 hours to obtain a toluene mixture containing silica spheres containing water.

Example 7

1,2-bis (10,12-tricosadinoyl) -sn-glycero-3-phosphocholine obtained from a mixture of ethanol and water was dispersed in distilled water, followed by a small amount of tetrakis (2-methoxyethoxy). After adding the silane, it is left at room temperature for 4 hours or more to obtain a tube surrounded by silica shell.

Example 8

Dissolve 10 microliters of tetraethoxysilane in 1 mL of toluene, mix 5 mL of a 3% solution of cetyltrimethylammonium bromide made with distilled water and stir with a homogenizer. After adding 100 microliters of tetrakis (2- (2-methoxyethoxy) ethoxy) silane to the mixture, the mixture was left for about 4 hours, then the external pH was lowered to 2 or less, and left for about 2 hours. Silica produced from tetraethoxy silane is produced on the surface of silica produced from (2-methoxyethoxy) ethoxy) silane.

Example 9

1 mL of toluene containing 3% polystyrene and 5 mL of 3% cetyltrimethylammonium bromide prepared in distilled water were stirred with a homogenizer to prepare an emulsion, followed by 100 microliters of tetrakis (2- (2-methoxyethoxy ) Ethoxy) silane is added. The mixture is left to stand for about 4 hours, and then dried in air to obtain a hollow sphere with walls of silica-polystyrene.

As described above, the silica structure generation method produced in the present invention requires little setting of the reaction conditions, and does not distinguish gas-liquid, liquid-liquid, liquid-solid interface, w / o, o / w, and the like. The silica structure can be obtained very simply and easily. The present invention produces silica structures at any temperature between pH 2 and pH 12 and at any temperature between 10 and 200 degrees Celsius, so that almost all of the Silica structures can be produced simply under conditions. Therefore, by applying the present invention, it is possible to wrap or protect a material or organisms sensitive to temperature, pH, etc. with silica or to separate them. In addition, by encapsulating and polymerizing the polymerizable monomer with silica, a polymer sphere having a surface of silica can be prepared, and by using an appropriate amount of polystyrene, a hollow sphere can be prepared whose walls are composed of silica and polystyrene together. Likewise, a tube made of lipids can be used to make a very simple tube of silica and lipids. The time it takes to complete this process can be adjusted from a few seconds to several hours as desired, and to obtain pure silica spheres and tubes, it is necessary to heat and burn off the organics.

Claims (19)

Process for preparing silica structures at gas-liquid, liquid-liquid, liquid-solid interface without artificial conditional change at any conditions between pH 2 and 12 using amphoteric silica precursors The method of claim 1, wherein the amphoteric silica precursor is used as tetrakis (2- (2-methoxyethoxy) ethoxy) silane or tetrakis (2-methoxyethoxy) silane. Process for producing silica structure by producing silica at liquid-liquid, gas-liquid and liquid-solid interface without artificial condition change at conditions between 12 and 12 The method according to claim 2, wherein surfactants such as cetyltetramethylammonium bromide, Span, Tween, dihexadecyldimethylammonium bromide, and dododecyldimethyl ammonium bromide are used for preparing the gas-liquid interface, and Method for producing silica structure by standing in between Cetyltetramethylammonium bromide, Span, Tween, Dihexadecyldimethylammonium bromide, Didodecyldimethyl ammonium bromide, Dioleoylphosphatidylethanolamine, Dioleoyl glycerophosphocholine, Dioleo according to claim 2 Phosphocidylethanolamines such as monoglycerophosphoglycerol sodium salt, dioleoyltrimethylammonium propane, phosphocholine, glycerol salt, tetraammonium bromide and the like were used to prepare the liquid-liquid interface at 50 to 10 degrees Celsius. Method for producing silica structure by standing in between The process for producing a structure with further strengthened silica walls by heating the silica structure obtained according to claim 4 between 50 and 200 degrees Celsius. 3. A tube surrounded by silica is prepared by using a tube made of 1,2-bis (10,12-tricosadiinoyl) -sn-glycero-3-phosphocholine as a liquid-solid interface. Way The method for producing a tube consisting of silica by heating the silica-recharge tube obtained according to claim 6 between 200 degrees Celsius and 500 degrees Celsius to burn off the lipid. 3. The method of claim 2, wherein the rate of silica structure formation is controlled between 4 seconds and 4 hours, the shortest time that can be observed using phosphate buffer as water phase. The method according to claim 2, wherein the living microorganism is olive oil, mineral oil, soybean oil, corn oil in an oil phase, distilled water or a buffer solution in water, and a reverse phase emulsion is prepared to surround the silica spheres in water. The method of claim 2 wherein the styrene, methyl methacrylate, methyl acrylate with AIBN or benzoyl peroxide in the oil phase to prepare a silica shell and heated to between 70 to 150 degrees Celsius to prepare a silica sphere filled with polymer How to The tetrakis (2- (2-methoxyethoxy) ethoxy) silane according to claim 2, wherein toluene containing 1-10% of tetraethoxysilane, tetramethoxysilane and trimethoxyvinyl silane is used as an oil phase. And a method of preparing a thicker layer of silane by preparing a silica shell with tetrakis (2-methoxyethoxy) silane and lowering the pH to 2 or less. The method of claim 2, wherein the toluene containing 3-20% of polystyrene as an oil layer is used as an oil phase to maintain a spherical shape even when dried in air and to form a hollow silica-polystyrene mixed wall. 13. The method of claim 12, wherein a colored hollow silica-polystyrene mixed wall sphere is prepared by dissolving hydrophobic dyes such as Sudan I, Sudan II, Sudan III, Oil Blue in a polystyrene solution. The method of claim 13, wherein the sphere obtained is heated between 200 and 500 degrees Celsius to burn off polystyrene to prepare a sphere having a wall composed of only silica. The method of producing a silica sphere having a carbon-based content as an oil layer of peryl alcohol and paratoluenesulfuric acid polymerized at a low molecular weight. The silica sphere prepared by using a hydrophobic oil layer such as hydrophobic monomers such as diallyloxy thiophene and aniline, and an amphoteric initiator such as Beier's Beromium C and iron chloride, and polymerized by leaving the mixture to stand. Method of manufacturing silica sphere The gas-containing silica is prepared by dissolving the surfactant prepared in claim 4 in a phosphate buffer solution of pH 7.4, pH 9, and pH 10 with vigorous stirring to form a foam as a liquid-gas interface. How to make a sphere 18. The process according to claim 17, wherein the reaction mixture is stirred in a space filled with gas, including oxygen, nitrogen, helium, argon, and the resulting foam is used as a liquid-gas interface to produce silica spheres containing the corresponding gas. 19. A method for producing a silica sphere having a harder wall by placing the silica sphere obtained in claim 18 in a pressure vessel filled with the gas.