JPH11246665A - Self-retaining porous silica and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a copolymer excellent in transparency and self-retaining properties, capable of presenting porous silica having a high specific surface area and useful for minute molecule-permeable materials, optical catalysts, catalyst carriers, etc., by polymerizing a mixture of specific silane compounds in the presence of a surfactant. SOLUTION: This production of self-retaining porous silica is to copolymerize (B) a tetraalkoxysilane [e.g., the alkoxy is a 1-5C (branched) alkoxy] with (C) an alkenyltrialkoxysilane [e.g. the alkoxy is a 1-5C (branched) alkoxy and the alkenyl is a 2-5C (branched) alkenyl] in the presence of (A) a surfactant [e.g. a 14-30C (branched) alkyltrimethylammonium chloride]. The copolymer is obtained, e.g. by using 0.05-0.5 mole times of the component A based on the sum total mole number of the components B and C and copolycondensing them in the presence of water in an acidic condition. The objective porous silica is obtained by baking the copolymer and removing the component A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a novel silane copolymer. More specifically, the present invention is a copolymer obtained by polymerizing tetraalkoxysilane and alkenyl trialkoxysilane in the presence of a surfactant, and has a high self-holding property and a high specific surface area porous silica. About.

[0002]

2. Description of the Related Art Materials having nano-sized micropores, which can transmit small molecules such as molecular water and air but cannot transmit large objects such as liquid water, are used for clothing and packaging. It is a coating material for materials. In addition, a material having nano-sized micropores is used for a packaging material, a sheet, or the like as a material having air permeability, particularly, oxygen permeability. These micromolecule permeable materials are required to have not only porosity related to the permeability of micromolecules but also various properties such as transparency and self-holding property. Also, sensors,
It has also been applied as a photocatalyst, taking advantage of its transparency, especially its transparency.

The present inventor has proposed a solution obtained by hydrolyzing and polymerizing a tetrafunctional alkoxysilane such as tetramethoxysilane or tetraethoxysilane in the presence of a surfactant alkyltrimethylammonium salt on a substrate. By spin-coating, a meso-like structure of the surfactant surfactant is obtained on the base plate, and a transparent thin film with a thickness of about 1 mm is obtained. (M. Ogawa, J. Am. Chem. Soc., 116, 7941 (199
4); M. Ogawa, Chem. Commun., 1149 (1996)).

However, the polymer obtained by this known method has insufficient self-holding properties of the membrane, and has a problem in handling properties of the membrane, which hinders practical use.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a porous silica material which is excellent not only in porosity and transparency but also in self-holding property.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a copolymer obtained by polymerizing tetraalkoxysilane and alkenyl trialkoxysilane in the presence of a surfactant, a porous silica material comprising the same, and a self-retaining material. The present invention relates to a silica material that is a film. As the surfactant used in the present invention,
Alkyltrimethylammonium salts are preferred. Also,
The copolymer of the present invention is characterized by being porous and self-holding. Further, the present invention provides a method for co-condensing tetraalkoxysilane and alkenyl trialkoxysilane in the presence of a surfactant, followed by calcining the copolycondensation of porous tetraalkoxysilane and alkenyl trialkoxysilane. The present invention relates to a method for manufacturing a united product.

The alkoxy group of the tetraalkoxysilane used in the present invention is a linear or branched alkoxy group having 1 to 15, preferably 1 to 10, more preferably 1 to 5 carbon atoms. Methoxy, ethoxy, propoxy and the like. The four alkoxy groups of the tetraalkoxysilane of the present invention may be the same or different from each other, but those having the same alkoxy group are preferred. In the tetraalkoxysilane of the present invention, part or all of the alkoxy groups may be substituted or unsubstituted phenoxy groups. Examples of the tetraalkoxysilane of the present invention include tetramethoxysilane (TMOS), tetraethoxysilane, tetrapropoxysilane, dimethoxydiethoxysilane, and the like.

The alkoxy group of the alkenyl trialkoxysilane used in the present invention may be the above-mentioned alkoxy group, and these alkoxy groups may be the same or different. The alkenyl group of the alkenyl trialkoxysilane has 2 to 1 carbon atoms.
5, preferably 2 to 10, more preferably 2 to 5, linear or branched alkenyl groups, such as a vinyl group, a 1-propylene group, and a 1-butylene group. The number of alkoxy groups in the alkenyl trialkoxysilane of the present invention need not be three, but may be two, and part or all of the alkoxy groups may be substituted or unsubstituted phenoxy groups. As the alkenyl trialkoxysilane of the present invention, vinyltrimethoxysilane (V
TMOS), vinyltriethoxysilane, vinyltripropoxysilane, 1-propylenetrimethoxysilane,
Examples thereof include 1-propylenetriethoxysilane, 1-propylenetripropoxysilane, and vinyldimethoxyethoxysilane.

The use amount of the alkenyl trialkoxysilane of the present invention is not more than the equivalent amount of tetraalkoxysilane, preferably 0.01 to 0.8 mol of alkenyl trialkoxysilane per mol of tetraalkoxysilane. Preferably it is 0.1-0.5 mol.

[0010] The surfactant used in the present invention includes:
There is no particular limitation as long as tetraalkoxysilane and alkenyl trialkoxysilane can be co-condensed.
This is because when the copolymer obtained by the polymerization reaction is calcined, the surfactant present at the time of the polymerization reaction is removed. However, as described below, since the ordered structure of the obtained copolymer seems to depend on the type and size of the surfactant used in the polymerization reaction,
It is necessary to select a surfactant according to a desired ordered structure.

As the surfactant used for such a purpose, a tetraalkylammonium salt is preferable. The alkyl group of the tetraalkylammonium salt is a linear or branched alkyl group having 1 to 30, preferably 1 to 20 carbon atoms. The four alkyl groups may be the same or different. However, an alkyltrimethyl form is preferred. The alkyl group of the alkyltrimethylammonium salt preferably has a relatively long chain having 14 or more carbon atoms. The counter ion of the tetraalkylammonium salt of the surfactant is preferably a halogen ion such as a chloride ion or a bromine ion, but is not limited thereto. As the tetraalkylammonium salt of the surfactant, tetradecanyltrimethylammonium chloride, hexadecyltrimethylammonium chloride,
Octadecyl trimethyl ammonium chloride, eicosanyl trimethyl ammonium chloride and the like can be mentioned.

The surfactant is used in an amount of 0.05 to 0.5 mol, preferably 0.1 to 0.3 mol, based on the total number of moles of tetraalkoxysilane and alkenyl trialkoxysilane. There is, but not particularly limited.

The copolymer of tetraalkoxysilane and alkenyl trialkoxysilane of the present invention is obtained by co-condensing tetraalkoxysilane and alkenyl trialkoxysilane in the presence of a surfactant, and then calcining the resultant. Can be manufactured. The co-condensation reaction is performed in the presence of water. The reaction conditions may be ordinary hydrolysis conditions, and the reaction temperature is from room temperature to the boiling point of the solvent, preferably from room temperature to about 80 ° C. The pH may be on the acidic side. It is not necessary to use a solvent in addition to water, but an organic solvent that can be mixed with water can be used in combination.

The solution obtained by the copolymerization reaction is preferably developed into a sheet and dried by a usual method. The sheet can be developed into a sheet shape by a usual molding method, but in particular, when a thin film is manufactured, a method by spin coating can also be used. Thereafter, the obtained dried product is fired. The firing can be performed in air, but is not limited thereto. The baking temperature is not particularly limited as long as the surfactant existing at the time of the reaction is removed, but is not less than 250 ° C., preferably 30 ° C.
0 ° C. or higher.

The copolymer of the present invention is a transparent and self-holding mesostructure. In the X-ray diffraction pattern, one diffraction peak is seen at a low angle. FIG. 1 shows that octadecanyltrimethylammonium chloride (C ₁₈ TAC) ((a) in FIG. 1) and hexadecyltrimethylammonium chloride (C ₁₆ TAC) ((b )), tetradecanyl trimethylammonium chloride (C ₁₄ TAC) (in Figure 1 (c)), dodecanylamine trimethylammonium chloride (C ₁₂ TAC) (in Figure 1 (d)), using X of the produced copolymer of the present invention
It is a line diffraction pattern. The d value obtained from this X-ray diffraction pattern varies depending on the alkyl chain length of the surfactant used, and includes C ₁₈ TAC, C ₁₆ TAC, and C ₁₄ T
At AC, 3.63, 3.34 and 3.20 respectively
nm (see FIG. 2). FIG. 2 shows the d values obtained from the X-ray diffraction pattern. The black triangles indicate the d values before firing when each surfactant was used, and the black squares indicate the values after firing. The d value is shown. Further, it was found that the macroscopic form was maintained even after the removal of the surfactant by firing, the peak in the X-ray diffraction pattern remained, and the ordered structure was maintained.

It has been shown that the surfactant used in the polymerization reaction contributes to the formation of an ordered structure in the mesostructure of the copolymer of the present invention. In the method of the present invention, it is considered that an ordered structure is formed as the solvent is volatilized, but it is difficult to obtain a self-holding film in a conventional system using tetramethoxysilane (TMOS) alone. On the other hand, a self-holding mesostructured film was obtained by adding trifunctional vinyltrimethoxysilane (VTMOS).
This is because the trifunctional vinyltrimethoxysilane (V
It is considered that the addition of (TMOS) decreases the gelation rate of the product, but this was unexpected.

FIG. 3 shows a Fourier transform infrared spectrum (FTIR) of the copolymer of the present invention. 2, (a), (b), (c), and (d) show octadecanyltrimethylammonium chloride (C ₁₈ TAC) (FIG. 2) as a surfactant in the same manner as in FIG. (A)), hexadecyltrimethylammonium chloride (C ₁₆ TAC) ((b) in FIG. 2), tetradecanyltrimethylammonium chloride (C ₁₄ TAC) ((c) in FIG. 2) 2 shows a copolymer of the present invention produced using Dodecanyltrimethylammonium chloride (C ₁₂ TAC) ((d) in FIG. 2).

FIG. 4 shows a thermogravimetric analysis (TG) and a differential thermal analysis (DTA) of the copolymer of the present invention prepared using octadecanyltrimethylammonium chloride (C ₁₈ TAC) as a surfactant. It is shown.

The present invention provides a porous silicic copolymer having excellent transparency and self-holding property and a high specific surface area, and particularly provides a material useful as a film-shaped or sheet-shaped molded product. Is what you do.

[0020]

EXAMPLES Next, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

Example 1 1 g (3 mol (molar ratio)) of tetramethoxysilane (TMOS) and vinyltrimethoxysilane (VTMOS)
0.325 g (1 mol (reference molar ratio)) was put into water, and 0.350 g (0.5 mol (molar ratio)) of hexadecyltrimethylammonium chloride (C ₁₆ TAC) was added thereto. (PH <1). This mixture was reacted at 20 ° C. to obtain a homogeneous solution. The obtained uniform solution was spread on a substrate and dried at 60 ° C. for 24 hours to obtain a target copolymer. In the air,
The copolymer was calcined at 550 ° C. for 5 hours to remove the surfactant, thereby obtaining a copolymer. The X-ray diffraction pattern of the obtained copolymer is shown in FIG.
((A) in FIG. 1), the Fourier transform infrared spectrum (FTIR) is shown in FIG. 3 ((a) in FIG. 3), and thermogravimetric analysis (TG) and differential thermal analysis (DTA) are shown in FIG. . The obtained copolymer was porous and excellent in self-holding property.

Example 2 A copolymer was used in the same manner as in Example 1 except that octadecyltrimethylammonium chloride (C ₁₈ TAC) was used instead of the hexadecyltrimethylammonium chloride of Example 1. A coalescence was obtained. The X-ray diffraction pattern of the obtained copolymer is shown in FIG. 1 ((b) in FIG. 1), and the Fourier transform infrared spectrum (FTIR) is shown in FIG. 3 ((b) in FIG. 3). The obtained copolymer was porous and excellent in self-holding property.

Example 3 In the same manner as in Example 1 except that the surfactant used was tetradecanyltrimethylammonium chloride (C ₁₄ TAC) instead of hexadecyltrimethylammonium chloride of Example 1. A copolymer was obtained. The X-ray diffraction pattern of the obtained copolymer is shown in FIG. 1 ((c) in FIG. 1), and the Fourier transform infrared spectrum (FTIR) is shown in FIG. 3 ((c) in FIG. 3). The obtained copolymer was porous and excellent in self-holding property.

Example 4 A surfactant was used in the same manner as in Example 1 except that dodecanyltrimethylammonium chloride (C ₁₂ TAC) was used instead of the hexadecyltrimethylammonium chloride of Example 1. A polymer was obtained. X of the obtained copolymer
The line diffraction pattern is shown in FIG. 1 ((d) in FIG. 1), and the Fourier transform infrared spectrum (FTIR) is shown in FIG. 3 ((d) in FIG. 3). The obtained copolymer was porous and excellent in self-holding property.

[0025]

The present invention is excellent in transparency and self-holding property,
It is intended to provide a porous silicic copolymer having a high specific surface area, and particularly to provide a material useful as a film-shaped or sheet-shaped molded product.

[Brief description of the drawings]

FIG. 1 shows an X-ray diffraction pattern of a copolymer of the present invention.

FIG. 2 shows the d value of the copolymer of the present invention.

FIG. 3 shows FTIR of the copolymer of the present invention.

FIG. 4 shows the thermogravimetric analysis (T
G) and Differential Thermal Analysis (DTA).

[Explanation of symbols]

(A) A copolymer using octadecanyltrimethylammonium chloride (C ₁₈ TAC) as a surfactant. (B) A copolymer using hexadecyltrimethylammonium chloride (C ₁₆ TAC) as a surfactant. (C) tetradecanyl trimethylammonium chloride as a surfactant (C ₁₄ TAC) those using a copolymer was used. (D) A copolymer using dodecanyltrimethylammonium chloride (C ₁₂ TAC) as a surfactant.

Claims (6)

[Claims] 1. A copolymer obtained by polymerizing tetraalkoxysilane and alkenyl trialkoxysilane in the presence of a surfactant. 2. The copolymer according to claim 1, wherein the surfactant is an alkyl trimethyl ammonium salt. 3. The copolymer according to claim 1, which is porous and self-holding. 4. A porous silica material comprising the copolymer according to claim 1, 2 or 3. 5. The porous silica material according to claim 4, which is a self-holding film. 6. A copolymer of a porous tetraalkoxysilane and an alkenyl trialkoxysilane obtained by co-condensing a tetraalkoxysilane and an alkenyl trialkoxysilane in the presence of a surfactant and then calcining the copolycondensate. Manufacturing method.