JP4868432B2 - Method for producing mesoporous silica structure, mesoporous silica structure, and liquid crystal element having the same - Google Patents

Description

  The present invention relates to a method for producing a mesoporous silica structure, and more specifically, a method for producing a mesoporous silica structure capable of producing a mesoporous silica structure having a high porosity and high mechanical strength at low cost, and a method for producing the same. And a liquid crystal device having the mesoporous silica structure obtained by the above method.

  Conventionally, porous structures have been used in various fields such as adsorption and separation because of their large porosity and specific surface area. As a porous structure having a silica skeleton, zeolite useful as a uniform microporous material having a pore diameter of 0.1 to 2 nm is well known in the art. A mesoporous silica structure having a pore diameter of 2 to 50 nm produced in the above manner has been reported. In the production of a mesoporous silica structure, a tetra-alkoxysilane is hydrolyzed under an acidic condition, and then a solution obtained by mixing a surfactant with the obtained hydrolyzate is applied to a substrate and dried to obtain a silica-surfactant. It has been proposed to form a nanocomposite (see Patent Document 1).

  In the production of a mesoporous silica structure manufactured using a conventional surfactant aggregate as a mold, pores are formed by baking at a high temperature of about 400 ° C. or more to remove the surfactant. When fired at such a high temperature, the mesoporous silica structure shrinks or breaks, and there is a problem that the porosity cannot be increased. In addition, when firing at a high temperature of 400 ° C. or higher, energy consumption increases, which causes a problem of increased production costs.

In order to solve such a problem, a technique for extracting a surfactant using an extractant such as acetic acid, hydrochloric acid, and ethanol has been proposed (see Patent Document 2). According to this technology, since the surfactant can be extracted at room temperature, there is an advantage that a mesoporous silica structure can be produced at a low cost. Since the surface active agent cannot be completely removed, the surfactant cannot be completely extracted and removed. As a result, the surface active agent remains in the pores and the porosity cannot be increased. It was. This problem is particularly remarkable in the case of a mesoporous silica thin film.
Japanese Patent Laid-Open No. 9-194298 JP 2002-53773 A

  The present invention aims to solve this problem.

  That is, according to the present invention, a mesoporous silica structure having a high porosity and excellent mechanical strength can be obtained without firing the composite from which the solvent has been removed at a high temperature to remove the surfactant. It is an object of the present invention to provide a method for producing a mesoporous silica structure that can be produced at a low cost, a mesoporous silica structure obtained by the production method, and a liquid crystal element having the mesoporous silica structure.

The present inventors have obtained a silica sol solution obtained by subjecting tetraethyl orthosilicate or tetramethyl orthosilicate to a hydrolysis reaction at a temperature of 35 ° C. to 70 ° C. for 60 minutes to 300 minutes in the presence of an acidic catalyst. When the surfactant is decomposed and removed by applying plasma treatment to the composite (silica-surfactant nanocomposite) formed from the solution obtained by adding the surfactant to the composite, the solvent is removed as before. The present invention was completed by finding that a mesoporous silica structure having a high porosity and excellent mechanical strength can be produced at a low cost without firing the surfactant at a high temperature and removing the surfactant.

In order to achieve the above object, the invention described in claim 1 includes: (b) a step of forming a complex with a solution obtained by adding a surfactant to a silica sol solution; and (b) from the complex In the method for producing a mesoporous silica structure , which sequentially comprises: a step of removing a solvent; and (c) a step of subjecting the composite from which the solvent has been removed to plasma treatment to decompose and remove the surfactant. A silica sol solution obtained by subjecting tetraethyl orthosilicate or tetramethyl orthosilicate in a solvent to a hydrolysis reaction at a temperature of 35 ° C. to 70 ° C. for 60 minutes to 300 minutes in the presence of an acidic catalyst. And a method for producing a mesoporous silica structure.

  The invention described in claim 2 is characterized in that, in the invention described in claim 1, the pH of the solvent is 2 or less.

The invention described in claim 3 is the invention described in claim 1 or 2 , wherein a hydrophobizing agent is added to the silica sol solution to hydrophobize the silica pore surface of the mesoporous silica structure. It is characterized by.

Invention described in claim 4 is the invention described in claim 1, is deposited said "silica sol solution a surfactant obtained by adding to the solution" to the substrate Thus, a composite is formed.

The invention described in claim 5 is the invention described in claim 4 , wherein the “solution obtained by adding a surfactant to a silica sol solution” is applied to a spin coating method, a dip coating method, or a spray coating method. Thus, a film is formed on the substrate.

The invention described in claim 6 is the invention described in claim 4 or 5 , wherein the mesoporous silica structure is a mesoporous silica film.

Invention described in claim 7 is the invention described in any one of claims 1 to 6, wherein the surfactant is characterized in that a nonionic surfactant.

The invention described in claim 8 is the invention described in claim 7 , wherein the nonionic surfactant is composed of a block copolymer.

The invention described in claim 9 is the invention described in claim 8 , wherein the block copolymer is a block copolymer of polyethylene oxide and polypropylene oxide.

The invention described in claim 10, in has been the invention according to any one of claims 1 to 9, wherein the plasma treatment is characterized in that the applied in an oxygen atmosphere.

The invention described in claim 11, in has been the invention according to any one of claims 1 to 10, wherein the plasma treatment is characterized in that the applied in the following low pressure conditions 10Torr .

The invention described in claim 12, in the invention described in any one of claims 1 to 11 hydrophobic on the pore surfaces of the plasma treatment is subjected to surfactant decomposition removal mesoporous silica structure It is characterized in that the processing is performed.

According to the first and second aspects of the invention, (a) a step of forming a complex with a solution obtained by adding a surfactant to a silica sol solution, and (b) removing the solvent from the complex. And (c) a step of subjecting the composite from which the solvent has been removed to plasma treatment to decompose and remove the surfactant, and a method for producing a mesoporous silica structure, wherein the silica sol solution is contained in the solvent. Since it is a silica sol solution obtained by hydrolyzing tetraethyl orthosilicate or tetramethyl orthosilicate at a temperature of 35 ° C. to 70 ° C. for 60 minutes to 300 minutes in the presence of an acidic catalyst, The mesoporous silica structure with high porosity and excellent mechanical strength can be manufactured at low cost without removing the surfactant by baking the composite from which the catalyst has been removed. Rukoto can.

According to the invention described in claim 3 , since the hydrophobizing agent is added to the silica sol solution to hydrophobize the silica pore surface of the mesoporous silica structure, the structure is difficult to shrink, A mesoporous silica structure having excellent temporal stability can be produced.

According to the invention described in claims 4 , 5 , 6 , the “solution obtained by adding a surfactant to a silica sol solution” is formed on a substrate to form a composite, and the At this time, the film is formed on the substrate by a spin coating method, a dip coating method, or a spray coating method, so that the film thickness can be easily controlled, a relatively large area can be easily applied, and productivity in the manufacturing process is improved good.

According to the invention described in claims 7 to 9 , since the surfactant is a nonionic surfactant, the volume of pores of the mesoporous silica structure is increased, and therefore the porosity is increased. be able to.

According to the invention described in claim 10 , since the plasma treatment is performed in an oxygen atmosphere, the surfactant can be removed more effectively.

According to the invention described in claim 11 , since the plasma treatment is performed under a low-pressure condition of 10 Torr or less, the surfactant can be removed in a shorter time, and therefore the productivity is improved. In addition, the possibility of causing shrinkage or destruction of the mesoporous silica structure can be reduced.

According to the invention described in claim 12 , since the hydrophobization treatment is performed on the pore surface of the mesoporous silica structure obtained by decomposing and removing the surfactant by performing the plasma treatment, the structure is difficult to shrink, A mesoporous silica structure having excellent temporal stability can be produced.

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a graph showing the relationship between the pH of a solvent that hydrolyzes alkoxysilane and the refractive index of a mesoporous silica structure. FIG. 2 is a graph showing the relationship between the plasma treatment time and the film thickness ratio (after treatment / before treatment). FIG. 3 shows a liquid crystal element having a mesoporous silica structure.

The method for producing a mesoporous silica structure of the present invention includes (a) a step of forming a complex with a solution obtained by adding a surfactant to a silica sol solution, and (b) a step of removing the solvent from the complex. (C) sequentially performing a plasma treatment on the composite from which the solvent has been removed to decompose and remove the surfactant. The silica sol solution is a silica sol obtained by subjecting tetraethyl orthosilicate or tetramethyl orthosilicate to a hydrolysis reaction at a temperature of 35 ° C. to 70 ° C. for 60 minutes to 300 minutes in the presence of an acidic catalyst. It is a solution.

Thus, (b) a step of forming a complex with a solution obtained by adding a surfactant to a silica sol solution, (b) a step of removing the solvent from the complex, and (c) removal of the solvent And a step of decomposing and removing the surfactant by subjecting the composite to plasma treatment , wherein the silica sol solution is tetraethyl orthosilicate or tetramethyl orthosilicate in a solvent. Is a silica sol solution obtained by hydrolysis reaction at a temperature of 35 ° C. to 70 ° C. for 60 minutes to 300 minutes in the presence of an acidic catalyst, the composite from which the solvent has been removed is calcined at a high temperature as in the prior art. There is no need to remove the surfactant, which reduces the possibility of the mesoporous structure shrinking and breaking, thus increasing the porosity and mechanical strength. Excellent mesoporous silica structure can be manufactured at a low cost.

  Since tetraethyl orthosilicate (TEOS) and tetramethyl orthosilicate (TMOS) are inexpensive and the reaction proceeds at a low temperature of less than about 100 ° C., it is possible to efficiently produce a mesoporous silica structure. .

FIG. 1 is a graph showing the relationship between the pH of a solvent that hydrolyzes alkoxysilane and the refractive index of a mesoporous silica structure. FIG. 1 shows that the smaller the refractive index value, the higher the porosity and the better the mesoporous structure. Therefore, in the present invention, when the silica sol solution is obtained by hydrolyzing tetraethyl orthosilicate or tetramethyl orthosilicate in the presence of an acidic catalyst in the solvent, the pH of the solvent is preferably 2 or less. When tetraethyl orthosilicate or tetramethyl orthosilicate is subjected to a hydrolysis reaction in the presence of an acidic catalyst to form a silica skeleton, the hydrolysis reaction is promoted in an acidic region having a low pH.

In this reaction, tetraethyl orthosilicate or the alkoxyl group (—O—R) of tetramethyl orthosilicate is hydrolyzed under acidic conditions to form a hydroxyl group (—OH), and then they are condensed. High molecular weight. Therefore, when a silica sol solution is obtained by hydrolyzing tetraethyl orthosilicate or tetramethyl orthosilicate in the presence of an acidic catalyst in a solvent, it is necessary to lower the pH of the solvent. The pH is preferably 2 or less, more preferably 1 or less.

  The porosity of the mesoporous silica structure obtained by subjecting the composite formed by changing the reaction temperature [° C.] and the reaction time [h] when hydrolyzing the alkoxysilane having the same composition to the plasma treatment is as follows: Table 1 shows.

  From Table 1, considering that the porosity that can be expected to function as a porous material is at least about 30% or more, from this result, the hydrolysis reaction of alkoxysilane proceeds to form a silane condensate well. It can be said that a minimum reaction temperature of 35 ° C. is necessary. On the other hand, when the reaction temperature exceeds 70 ° C., it becomes a high temperature close to the boiling point of ethanol (78 ° C.), which is not preferable because ethanol may evaporate during the reaction and the composition may change. The reaction time is required to be at least 1 hour, but if it exceeds 5 hours, the reaction proceeds so much that a good structure cannot be obtained. In Table 1, “-” indicates that a porous structure was not obtained.

Therefore, in the present invention, when a silica sol solution is obtained by hydrolyzing tetraethyl orthosilicate or tetramethyl orthosilicate in the presence of an acidic catalyst in a solvent, the reaction temperature is preferably 35 to 35. 70 ° C. The reaction time is preferably 60 to 300 minutes. In the reaction in which tetraethyl orthosilicate or tetramethyl orthosilicate is hydrolyzed in the presence of an acidic catalyst to form a silica skeleton, the higher the temperature, the faster the reaction rate and the longer the reaction proceeds. . In the present invention, an alkoxyl group (—O—R) is hydrolyzed and condensed to form a silica skeleton (—Si—O—) to be polymerized. Since a surfactant enters and gathers between them to form a composite in which the surfactant is incorporated in the silica skeleton, the amount of the silica skeleton when the surfactant is added, that is, the molecular weight of the condensate is It is necessary to be within an appropriate range, and if it is too little or too much, a complex with a surfactant is not well formed. In particular, when a mesoporous silica film is formed on a substrate, the film thickness and the like are also affected by the viscosity of the condensate of the silica source, so that more precise control of the reaction conditions is necessary. As a result of repeated investigations while variously changing the reaction conditions for alkoxysilane, the present inventors have found that when the reaction temperature is generally 35 to 70 ° C. and the reaction time is 60 to 300 minutes, It has been found that a composite with silica is well formed.

  In the present invention, by adding a hydrophobizing agent to the “silica sol solution” to hydrophobize the surface of the silica pores of the mesoporous silica structure, the structure is less likely to shrink and is stable over time. In addition, an excellent mesoporous silica structure can be produced. In the process of creating the present invention, depending on the preparation conditions of the sol solution, etc., the structure may shrink in the process of removing the surfactant by plasma treatment or after the removal. It turns out that it is one cause to lower. As a result of the study, the present inventors have found that this problem can be solved by hydrophobizing the pore surface of the mesoporous silica structure.

  The method of hydrophobizing is preferably a method of adding a silicon compound having a hydrophobizing part to the sol solution, but may be a method of hydrophobizing the pore surface of the structure after removing the active agent. The former can be achieved by adding an alkoxysilane having an alkyl group or a chlorosilane having an alkyl group. In the latter case, after the structure is formed, it is dried by immersing in 1,1,1,3,3,3-hexamethyldisilazane (HMDS), chlorosilane having an alkyl group or a solution thereof, or by exposing to the vapor. This can be achieved. Either method is effective in preventing the shrinkage of the mesoporous silica structure after the plasma treatment process and removal of the surfactant, but the production process is more effective when a hydrophobizing agent is added to the sol solution. It is a highly manufacturing method.

  Preferably, the complex is formed by forming a film on the substrate of the “solution obtained by adding a surfactant to a silica sol solution”, and adding the surfactant to the silica sol solution. The “solution obtained” may be formed by spray drying to form fine particles having a diameter of 1 μm or less, or the “solution obtained by adding a surfactant to a silica sol solution” can be obtained by further stirring. The precipitate may be formed by filtering and collecting to form particles, or the above-mentioned “solution obtained by adding a surfactant to a silica sol solution” is spun into a short fiber. May be formed. Therefore, the mesoporous silica structure produced in the present invention becomes a mesoporous silica film, mesoporous silica fine particles, mesoporous silica particles, or mesoporous silica fibers depending on the shape of the composite, as long as it is not contrary to the object of the present invention. The shape may be other than these shapes.

  The “solution obtained by adding a surfactant to a silica sol solution” is preferably formed on a substrate by a spin coating method, a dip coating method, or a spray coating method. When the “solution obtained by adding a surfactant to a silica sol solution” is formed on a substrate by a spin coating method, a dip coating method, or a spray coating method, it is easy to control the film thickness and has a relatively large area. Is easy to apply, and the productivity in the manufacturing process is good. In the present invention, an optimum coating method is used according to physical properties such as the viscosity of the solution to be coated, the required film thickness, and the like.

  The surfactant used in the present invention is preferably a nonionic surfactant. The nonionic surfactant is preferably a polyethylene oxide nonionic surfactant having a hydrocarbon group as a hydrophobic component and a polyethylene oxide chain as a hydrophilic component, and particularly preferably a plurality of polyalkylenes. A nonionic surfactant composed of a block copolymer having an oxide chain, for example, a block copolymer of ethylene oxide (EO) and propylene oxide (PO). When a nonionic surfactant composed of a block copolymer of ethylene oxide (EO) and propylene oxide (PO) is used, the pore volume of the mesoporous silica structure is increased, and therefore the porosity can be increased. .

The block copolymer of ethylene oxide and propylene oxide includes the following general formula (EO) x (PO) y (EO) x
(Wherein x and y represent the number of repetitions of EO and PO, respectively, preferably 5 ≦ x ≦ 110 and 20 ≦ y ≦ 90, more preferably 10 ≦ x ≦ 30 and 30 ≦ y ≦ 70.)
The triblock copolymer represented by these is mention | raise | lifted.

  The plasma treatment in the present invention is preferably performed in an oxygen atmosphere. As described above, when the plasma treatment is performed in an oxygen atmosphere, the surfactant can be oxidized and decomposed with oxygen, so that the surfactant can be more effectively removed. Here, the “oxygen atmosphere” means an atmosphere containing oxygen, and may contain a gas other than oxygen.

  The plasma treatment in the present invention is preferably performed under a low pressure condition of 10 Torr or less. As described above, when the plasma treatment is performed under a low pressure condition of 10 Torr or less, the surfactant can be removed in a shorter time, so that the productivity can be improved and the shrinkage of the mesoporous silica structure or The possibility of causing destruction can be reduced. The plasma processing time required to sufficiently remove the surfactant varies depending on the pressure conditions during processing. The processing time is shown in Table 2 below.

  On the other hand, when the plasma treatment time is long, the possibility of causing contraction or destruction of the mesoporous silica structure increases regardless of the pressure condition. FIG. 2 is a graph showing the relationship between the plasma treatment time and the film thickness ratio (after treatment / before treatment). From FIG. 2, it can be said that the mesoporous silica structure is contracted or broken because the film thickness is remarkably reduced when the plasma treatment time exceeds approximately 2 minutes. Therefore, if the plasma treatment is performed for about 2 minutes or less, there is a high possibility that the activator can be removed without impairing the mesoporous structure. Therefore, in the present invention, as described above, the pressure condition may be 10 Torr or less. More preferably, it is 2 Torr or less.

  Since the mesoporous silica structure produced by the method for producing a mesoporous silica structure of the present invention does not need to remove the surfactant by baking the composite from which the solvent has been removed at a high temperature as in the prior art, the porosity is low. High and excellent in mechanical strength.

  As shown in FIG. 3, the liquid crystal element 10 of the present invention includes a light absorption layer 2, a layer 3 made of the mesoporous silica structure, an electrode layer 4, between a pair of substrates 1 and 7. A liquid crystal layer 5 for controlling light transmittance and an electrode layer 6 are sequentially provided. By the way, since the mesoporous silica structure has hollow pores, the refractive index is lower than that of the base material. Therefore, in the liquid crystal element 10 of the present invention having such a mesoporous silica structure, light is efficiently reflected at the interface between the liquid crystal layer 5 and the layer 3 made of the mesoporous silica structure. Scattered light can be extracted efficiently, and is therefore suitable for high definition.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the following examples.

Example 1
Tetraethyl orthosilicate (hereinafter referred to as “TEOS”): water: ethanol: hydrochloric acid in a molar ratio of 1: 5: 5: 0.02-0.1 was stirred for 3 hours while heating to 50 ° C. . To this mixed solution, an ethanol solution of polyethylene oxide-polypropylene oxide-polyethylene oxide block copolymer (EO-b-PO-b-EO) was added as a surfactant and stirred, and then allowed to stand for 1 hour to obtain a silica sol solution. . The final composition of the silica sol solution was TEOS: water: ethanol: hydrochloric acid: (EO-b-PO-b-EO) at a molar ratio of 1: 5: 36: 0.02-0.1: 0.01. there were. This silica sol solution was formed on a quartz substrate by a spin coating method and then dried on a hot plate at 110 ° C. to form a composite made of a silica film in which a surfactant was dispersed. The composite formed in this manner was subjected to plasma treatment for 8 minutes under an atmospheric pressure of oxygen to obtain a film-like mesoporous silica structure. The film-like mesoporous silica structure thus obtained had a thickness of 266 nm with respect to a thickness of 280 nm of the composite made of the silica film in which the surfactant was dispersed. Further, when the refractive index of this membranous mesoporous silica structure was measured and the porosity was calculated from the measured value, the porosity was about 47%.

(Example 2)
A composite made of a silica film in which a surfactant dispersed in the same manner as in Example 1 was subjected to plasma treatment for 2 minutes in an oxygen atmosphere of 2 Torr (oxygen 100%) to obtain a film-like mesoporous silica structure. Obtained. The thickness of the mesoporous silica structure thus obtained is 275 nm with respect to the thickness of 280 nm of the composite made of the silica film in which the surfactant is dispersed, which is larger than that obtained in Example 1. There was little decrease in thickness. Further, when the refractive index of this membranous mesoporous silica structure was measured and the porosity was calculated from the measured value, the porosity was about 49%.

(Example 3)
Except that the mixed solution of TEOS: water: ethanol: hydrochloric acid in a molar ratio of 1: 5: 5: 0.02-0.1 was stirred for 3 hours while heating at 70 ° C., the same as in Example 1, A film-like mesoporous silica structure was obtained. The thickness of the mesoporous silica structure thus obtained was 260 nm with respect to the thickness of 280 nm of the composite composed of the silica film in which the surfactant was dispersed, which was larger than that produced in Example 1. The decrease in thickness was great. Further, when the refractive index of this membranous mesoporous silica structure was measured and the porosity was calculated from the measured value, the porosity was about 45%.

Example 4
Trimethylchlorosilane as a hydrophobizing agent was added in a molar ratio of 0.03 to TEOS in a silica sol solution prepared in the same manner as in Example 1 and stirred for 10 minutes. The silica sol solution to which the hydrophobizing agent was added was formed on a quartz substrate by spin coating, and then dried on a hot plate at 110 ° C. to form a composite made of a silica film in which a surfactant was dispersed. . The composite thus formed was subjected to plasma treatment for 2 minutes in an oxygen atmosphere of 2 Torr to obtain a film-like mesoporous silica structure. The thickness of the mesoporous silica structure thus obtained is 280 nm with respect to the thickness of 280 nm of the composite composed of the silica film in which the surfactant is dispersed, and the shrinkage of the film due to the removal of the surfactant. Was not happening at all. Further, the refractive index of this membranous mesoporous silica structure was measured, and the porosity was calculated from the measured value. As a result, the porosity was about 54%. Further, this film-like mesoporous silica structure was allowed to stand in a room with an air temperature of 25 ° C. and a humidity of 50% for one week and then evaluated in the same manner. However, no change was observed in the film thickness and the porosity.

(Example 5)
Indium tin oxide (ITO) is formed by sputtering on the membranous mesoporous silica structure formed in the same manner as in Example 2 to form a laminate having a quartz substrate, a mesoporous silica layer, and a transparent electrode in this order. did. However, the quartz substrate was previously spin-coated with a black matrix (CFPR BK-730S T-4, manufactured by Tokyo Ohka Kogyo Co., Ltd.) on the upper surface of the quartz substrate, and this was irradiated with UV, then baked and cured. Was used. Then, as shown in FIG. 3, an approximately 30 μm-thick liquid crystal layer composed of polymer dispersed liquid crystal, a transparent electrode composed of ITO, and a quartz substrate are sequentially laminated on the transparent electrode of this laminate. Thus, a liquid crystal element was obtained. Next, in order to evaluate the reflectance of the liquid crystal element thus obtained, when the light receiving part is placed in the normal direction of the viewing surface and a white light source is applied from a direction inclined by 30 ° from the normal line The reflected light to the light receiving part was measured. The reflection intensity measured on a standard white plate under the same conditions as 100% was taken as the reflectance ratio. As a result, the reflectance of the liquid crystal element was about 33%.

(Comparative Example 1)
A film-like mesoporous silica structure was obtained in the same manner as in Example 1 except that the composite was subjected to heat treatment in an oven at 400 ° C. to decompose and remove the surfactant. The thickness of the mesoporous silica structure thus obtained is 254 nm with respect to the thickness of 280 nm of the composite composed of the silica film in which the surfactant is dispersed, and the film thickness is remarkably reduced by the high temperature treatment. It was. Further, when the refractive index of this membranous mesoporous silica structure was measured and the porosity was calculated from the measured value, the porosity was about 45%.

(Comparative Example 2)
A liquid crystal element was obtained in the same manner as in Example 5 using the membranous mesoporous silica structure obtained in Comparative Example 1. The reflectance of the liquid crystal element thus obtained was measured in the same manner as in Example 5. As a result, the reflectance was about 25%.

It is a graph which shows the relationship between pH of the solvent which hydrolyzes alkoxysilane, and the refractive index of a mesoporous silica structure. It is a graph which shows the relationship between plasma processing time and film thickness ratio (after processing / before processing). It is a liquid crystal element having a mesoporous silica structure.

DESCRIPTION OF SYMBOLS 1,7 Substrate 2 Light absorption layer 3 Layer made of mesoporous silica structure 4,6 Electrode layer 5 Liquid crystal layer

Claims (12)

(B) a step of forming a complex with a solution obtained by adding a surfactant to a silica sol solution, (b) a step of removing the solvent from the complex, and (c) a complex from which the solvent has been removed. And a step of decomposing and removing the surfactant by performing plasma treatment , wherein the silica sol solution is obtained by using tetraethyl orthosilicate or tetramethyl orthosilicate as an acidic catalyst in a solvent. A method for producing a mesoporous silica structure, which is a silica sol solution obtained by a hydrolysis reaction at a temperature of 35 ° C to 70 ° C for 60 minutes to 300 minutes. The method for producing a mesoporous silica structure according to claim 1 , wherein the solvent has a pH of 2 or less. The method for producing a mesoporous silica structure according to claim 1 or 2 , wherein a hydrophobizing agent is added to the silica sol solution to hydrophobize the silica pore surface of the mesoporous silica structure. Mesoporous silica according to any one of claims 1 to 3, characterized in that to form a complex by forming said "silica sol solution a surfactant obtained by adding to the solution" to the substrate Manufacturing method of structure. 5. The mesoporous silica according to claim 4 , wherein the “solution obtained by adding a surfactant to a silica sol solution” is formed on a substrate by a spin coating method, a dip coating method, or a spray coating method. Manufacturing method of structure. The method for producing a mesoporous silica structure according to claim 4 or 5 , wherein the mesoporous silica structure is a mesoporous silica film. The surfactant, manufacturing method of mesoporous silica structure according to any one of claims 1 to 6, wherein the nonionic surfactant. The method for producing a mesoporous silica structure according to claim 7 , wherein the nonionic surfactant is composed of a block copolymer. The method for producing a mesoporous silica structure according to claim 8 , wherein the block copolymer is a block copolymer of polyethylene oxide and polypropylene oxide. The plasma processing method of producing a mesoporous silica structure according to any one of claims 1 to 9, characterized in that applied in an oxygen atmosphere. The plasma processing method of producing a mesoporous silica structure according to any one of claims 1 to 10, characterized in that applied in the following low pressure conditions 10 Torr. Mesoporous silica structure according to any one of claims 1 to 11, wherein applying a hydrophobic treatment to the pore surfaces of the plasma treatment performed mesoporous silica structure the surfactant was decomposed and removed by Production method.

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