WO2017195715A1 - Sol and gel comprising alkoxysilanes and polyrotaxane - Google Patents

Abstract

The invention provides a silica aerogel having desired properties in terms of the heat-insulating property, transparency, and mechanical strength. The invention provides a sol comprising (a) SIR¹ _n(OR²)_4-n (in the formula, R¹ and R² each independently represent a C1-20 linear or branched alkyl group, C3-20 cyclic alkyl group, or optionally substituted phenyl group, n represents an integer of 0-3) and (b) a polyrotaxane obtained by arranging blocking groups so that cyclic molecules are not eliminated at both ends of a pseudopolyrotaxane in which cyclic molecules are included in a manner such that the openings thereof are skewered by linear molecules.

Description

Sol and gel comprising alkoxysilanes and polyrotaxane

The present invention relates to a sol comprising alkoxysilanes and a polyrotaxane, a gel obtained from the sol, a method for producing the sol, and a method for producing the gel.
The present invention also relates to novel alkoxysilanes or novel modified polyrotaxanes that form the sol.

Silica airgel, which is a very low density porous material, needs to have both heat insulation and transparency, such as window materials, because it exhibits very high heat insulation and transparency due to its fine pores. Application to the material is expected. However, application of aerogels composed only of silica has not progressed due to their mechanical vulnerability.

In order to solve this problem of mechanical vulnerability, a composite airgel in which a polymer is blended with silica has been proposed (Non-Patent Document 1) instead of silica-only aerogel. In Non-Patent Document 1, for example, a composite aerogel is prepared by blending polyacrylate resin, polyamide resin, epoxy resin, polystyrene, polyurea, or the like as a polymer.

However, the composite airgel can solve the problem of mechanical vulnerability, but has a problem that causes a remarkable decrease in transparency. Specifically, by blending a polymer, only the airgel having transparency deteriorated and becoming turbid can be prepared, and there is a problem that application to a material requiring transparency is hindered.

Therefore, an object of the present invention is to solve the above problems.
Specifically, an object of the present invention is to provide a silica-based airgel having desired properties in heat insulation, transparency and mechanical strength.
Moreover, the objective of this invention is providing the sol for obtaining this silica type airgel in addition to the said objective.
Furthermore, the objective of this invention is providing the manufacturing method of the said sol, and the manufacturing method of the said gel in addition to the said objective or the said objective.
Another object of the present invention is to provide novel alkoxysilanes or novel modified polyrotaxanes that can form the sol in addition to or in addition to the above objects.

The inventors have found the following invention.
<1> (a) SiR ¹ _n (OR ² ) _4-n (wherein R ¹ and R ² are each independently a straight chain having 1 to 20, preferably 1 to 10, more preferably 1 to 4 carbon atoms) A chain or branched alkyl group, a cyclic alkyl group having 3 to 20 carbon atoms, preferably 3 to 10, more preferably 3 to 6 carbon atoms, or an optionally substituted phenyl group,
n represents an integer of 0 to 3, preferably 0 to 1, more preferably 0); and (b) the ends of the pseudopolyrotaxane in which the openings of the cyclic molecule are skewered by the linear molecule. A polyrotaxane in which a blocking group is arranged so that a cyclic molecule is not eliminated;
A sol comprising:

<2> In the above item <1>, (b) polyrotaxane has a cyclic molecule of —SiR ¹¹ _m (OR ¹² ) _3-m
(Wherein R ¹¹ and R ¹² are each independently a linear or branched alkyl group having 1 to 20, preferably 1 to 10, more preferably 1 to 4, carbon atoms, 3 to 20 carbon atoms, preferably Represents 3 to 10, more preferably 3 to 6 cyclic alkyl groups or optionally substituted phenyl groups;
m represents an integer of 0 to 2, preferably 0 to 1, more preferably 0)
It is good to have group represented by these.

<3> In the above item <1> or <2>, (b) the polyrotaxane has a cyclic molecule of —SiR ¹¹ _m (OR ¹² ) _3-m
(Wherein R ¹¹ and R ¹² are each independently a linear or branched alkyl group having 1 to 20, preferably 1 to 10, more preferably 1 to 4, carbon atoms, 3 to 20 carbon atoms, preferably Represents 3 to 10, more preferably 3 to 6 cyclic alkyl groups or optionally substituted phenyl groups;
m represents an integer of 0 to 2, preferably 0 to 1, more preferably 0)
Having a group represented by
The linker moiety may be a linear or branched alkyl group having 1 to 20 carbon atoms, an optionally substituted phenyl group, an ethylene glycol group or a group having a siloxane bond, preferably 1 to 20 carbon atoms, A linear or branched alkyl group or ethylene glycol group having 1 to 5 carbon atoms is preferable, and a linear or branched alkyl group having 1 to 20 carbon atoms, preferably 1 to 5 carbon atoms is more preferable.

<4> A gel obtained from the sol described in any one of <1> to <3> above.
<5> In the above item <4>, the gel may be an airgel.

<6> In the above <4> or <5>, the gel is an airgel,
The maximum compressive strain of the airgel should be 10% or more, preferably 30% or more, more preferably 50% or more, and most preferably 60% or more.

<7> In any one of the above items <4> to <6>, the gel may be an airgel, and the airgel may be transparent. Here, “transparent” means that, for example, an SEM image of an airgel does not show a particle size of 100 nm or more due to growth or aggregation of silica particles. The airgel having a thickness of 2 mm may transmit light having a wavelength of 550 nm by 60% or more, preferably 65 to 100%, more preferably 70 to 100%. Specifically, the transmittance T (2) at 2 mm can be obtained by substituting the transmittance T at 550 nm at another thickness d (mm) into the following formula (X).

<8> In any one of the above items <4> to <7>, the gel is an airgel,
The airgel has a porosity of 80% or more, preferably 85% or more, more preferably 90% or more.
<9> In any one of the above items <4> to <8>, the gel is an airgel, and the thermal conductivity of the airgel is 0.05 Wm ⁻¹ K ⁻¹ or less, preferably 0.02 Wm ⁻¹ K ⁻¹ or less. More preferably, it is 0.015 Wm ⁻¹ K ⁻¹ or less.

<10>
(A) SiR ¹ _n (OR ² ) _4-n
(Wherein R ¹ and R ² are each independently a linear or branched alkyl group having 1 to 20, preferably 1 to 10, more preferably 1 to 4 carbon atoms, 3 to 20 carbon atoms, preferably Represents 3 to 10, more preferably 3 to 6 cyclic alkyl groups or optionally substituted phenyl groups;
n represents an integer of 0 to 3, preferably 0 to 1, more preferably 0); and (b) the ends of the pseudopolyrotaxane in which the openings of the cyclic molecule are skewered by the linear molecule. A polyrotaxane in which a blocking group is arranged so that a cyclic molecule is not eliminated;
A method for preparing a sol comprising:
(I) a step of preparing (a) SiR ¹ _n (OR ² ) _4-n ;
(II) preparing (b) the polyrotaxane; and (III) mixing the (a) SiR ¹ _n (OR ² ) _4-n and the (b) polyrotaxane and performing hydrolysis;
The method as described above, wherein the sol is obtained.

<11>
(A) SiR ¹ _n (OR ² ) _4-n
(Wherein R ¹ and R ² are each independently a linear or branched alkyl group having 1 to 20, preferably 1 to 10, more preferably 1 to 4 carbon atoms, 3 to 20 carbon atoms, preferably Represents 3 to 10, more preferably 3 to 6 cyclic alkyl groups or optionally substituted phenyl groups;
n represents an integer of 0 to 3, preferably 0 to 1, more preferably 0); and (b) the ends of the pseudopolyrotaxane in which the openings of the cyclic molecule are skewered by the linear molecule. A polyrotaxane in which a blocking group is arranged so that a cyclic molecule is not eliminated;
A method for preparing a gel comprising:
(I) a step of preparing (a) SiR ¹ _n (OR ² ) _4-n ;
(II) a step of preparing the (b) polyrotaxane; and (III) the (a) SiR ¹ _n (OR ² ) _4-n and the (b) polyrotaxane are mixed and hydrolyzed to obtain a sol. Process;
(IV) A step of preparing the wet gel by allowing the obtained sol to stand;
A method for preparing a wet gel.

<12> a step of drying the wet gel obtained in the above <11>;
A method for preparing an airgel, further comprising:

<13> An airgel having a —Si—O—Si— bond and a group derived from a cyclic molecule, wherein the maximum compressive strain of the airgel is 10% or more, preferably 30% or more, more preferably 50% or more. Airgel, most preferably 60% or more.

<14>
A polyrotaxane in which a blocking group is arranged so that a cyclic molecule is not detached at both ends of a pseudo-polyrotaxane in which an opening of a cyclic molecule is included in a skewered manner by a linear molecule,
The cyclic molecule is represented by the following formula I
(Wherein X ¹¹ is a linear or branched alkylene group having 1 to 20 carbon atoms, preferably 2 to 18 carbon atoms, more preferably 2 to 10 carbon atoms (provided that non-adjacent carbon atoms are —CO—NH—, — NH-CO-, -CO-, -CO-O-, -O-CO- may be substituted), a group represented by-(CH ₂ -CH (R ²⁵ ) -O) _n- (formula R ²⁵ represents hydrogen or a linear or branched alkyl group having 1 to 8, preferably 1 to 6, and more preferably 1 to 4 carbon atoms, and n is 1 to 50, preferably 1 to 10, And more preferably represents an integer of 1 to 3, and a divalent group selected from the group consisting of combinations thereof;
R ²¹ to R ²³ are each independently a linear or branched alkyl group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 1 to 4 carbon atoms, 3 to 20 carbon atoms, preferably 3 to 10 carbon atoms, More preferably 3 to 6 cyclic alkyl groups or optionally substituted phenyl groups)
Have
The polyrotaxane, wherein the polyrotaxane is free of vinyl group.

According to the present invention, it is possible to provide a silica-based airgel having desired properties in heat insulation, transparency, and mechanical strength.
In addition to the above effects, the present invention can provide a sol for obtaining the silica-based aerogel.
Furthermore, according to the present invention, in addition to or in addition to the above effects, a method for producing the sol and a method for producing the gel can be provided.
In addition to the above effects or in addition to the above effects, the present invention can provide novel alkoxysilanes or novel modified polyrotaxanes that can form the sol.

3 shows an FT-IR spectrum of the triethoxysilyl-modified polyrotaxane synthesized in Example 1. The black line shows the FT-IR spectrum of polyrotaxane (HAPR) which is the starting material used in Example 1. Embodiment ¹ H NMR spectrum of Example starting material used in 1 polyrotaxane (HAPR) (in FIG. 2, indicated by "C"), ¹ H NMR spectrum of triethoxysilyl modified polyrotaxane synthesized in Example 1 (FIG. 2 And ¹ H NMR spectrum (shown as “B” in FIG. 2) of the reaction product obtained in Example 1. 3 shows SEC chromatograms of the triethoxysilyl-modified polyrotaxane synthesized in Example 1 and the polyrotaxane (HAPR) that is the starting material used in Example 1. FIG. The thermogravimetric analysis results of the polyrotaxane-reinforced silica airgels A-1 to A-5 obtained in Examples 2 to 6 are shown. The SEM image inside a polyrotaxane reinforced silica airgel A-1 is shown.

Hereinafter, the invention described in the present application will be described in detail.
The present application provides a sol comprising an alkoxysilane and a polyrotaxane, a gel obtained from the sol, a method for producing the sol, and a method for producing the gel.
The present application also provides novel modified polyrotaxanes that form the sol or novel alkoxysilanes from a different point of view. Hereinafter, it demonstrates in order.

<Sol comprising alkoxysilanes and polyrotaxane>
The present application provides a sol comprising an alkoxysilane and a polyrotaxane.
Specifically, the sol of the present application is
(A) SiR ¹ _n (OR ² ) _4-n
(Wherein R ¹ and R ² are each independently a linear or branched alkyl group having 1 to 20, preferably 1 to 10, more preferably 1 to 4 carbon atoms, 3 to 20 carbon atoms, preferably Represents 3 to 10, more preferably 3 to 6 cyclic alkyl groups or optionally substituted phenyl groups;
n represents an integer of 0 to 3, preferably 0 to 1, more preferably 0); and (b) the ends of the pseudopolyrotaxane in which the openings of the cyclic molecule are skewered by the linear molecule. A polyrotaxane in which a blocking group is arranged so that a cyclic molecule is not eliminated;
It has.

Here, “having” means having the above-mentioned components (a) and (b) and having them. Therefore, the sol may contain or contain components other than the above (a) and (b).
Further, the sol of the present application may be formed from only the components (a) and (b).
Hereinafter, the component (a) and the component (b) will be described in this order.

<< Ingredient (a) >>
The component (a) that forms the sol of the present application is represented by SiR ¹ _n (OR ² ) _4-n .
Here, R ¹ and R ² are each independently a linear or branched alkyl group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 1 to 4 carbon atoms, 3 to 20 carbon atoms, preferably 3 carbon atoms. Represents a cyclic alkyl group of 10 to 10, more preferably 3 to 6 or an optionally substituted phenyl group,
n represents an integer of 0 to 3, preferably 0 to 1, more preferably 0.

Component (a) may be a conventionally known substance or a newly synthesized substance.
More specifically, examples of the component (a) include tetraethoxysilane in which n is 0 and R ² is an ethyl group, and tetramethoxysilane in which n is 0 and R ² is a methyl group. Although it can, it is not limited to these.

<< Component (b) >>
Component (b) is a polyrotaxane in which blocking groups are arranged so that the cyclic molecules are not detached at both ends of the pseudopolyrotaxane in which the openings of the cyclic molecules are skewered by linear molecules.
Even if the polyrotaxane is a conventionally known polyrotaxane, for example, the polyrotaxane described in Japanese Patent No. 4521875, as described in detail below, the cyclic molecule is optionally —SiR ¹¹ _m (OR ¹² ) A polyrotaxane having a group represented by _3-m may be used.
Each component of the polyrotaxane, that is, “cyclic molecule”, “linear molecule”, and “blocking group” will be described later.

<< Polyrotaxane in which the cyclic molecule has a group represented by -SiR ¹¹ _m (OR ¹² ) _3-m >>
In the present application, the polyrotaxane as the component (b) preferably has a cyclic molecule having a group represented by —SiR ¹¹ _m (OR ¹² ) _3-m , optionally via a linker moiety.
Here, R ¹¹ and R ¹² are each independently a linear or branched alkyl group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 1 to 4 carbon atoms, 3 to 20 carbon atoms, preferably 3 carbon atoms. Represents a cyclic alkyl group of 10 to 10, more preferably 3 to 6 or an optionally substituted phenyl group,
m represents an integer of 0 to 2, preferably 0 to 1, more preferably 0.

The linker moiety may be a linear or branched alkyl group having 1 to 20 carbon atoms, an optionally substituted phenyl group, an ethylene glycol group, or a group having a siloxane bond, preferably 1 to 1 carbon atoms. It may be a linear or branched alkyl group or ethylene glycol group having 20, preferably 1 to 5, more preferably a linear or branched alkyl group having 1 to 20 carbon atoms, preferably 1 to 5 carbon atoms.
The cyclic molecule may have a group other than the above-described linker moiety and a group represented by —SiR ¹¹ _m (OR ¹² ) _3-m .
Other groups include acetyl group, propionyl group, hexanoyl group, methyl group, ethyl group, propyl group, 2-hydroxypropyl group, 1,2-dihydroxypropyl group, cyclohexyl group, butylcarbamoyl group, hexylcarbamoyl group, phenyl group , Polycaprolactone groups, or derivatives thereof, but are not limited thereto.

The polyrotaxane should be free of vinyl groups.
In the present specification, “vinyl group-free” means that vinyl group is not present at all or is present at 10 ⁻⁵ mol / g (1 / 100,000 mol per gram) or less.
The vinyl group in the polyrotaxane can be confirmed by measuring its presence by ¹ H NMR. Specifically, since a peak derived from a vinyl group appears at 5.8 to 6.3 ppm, in the present invention, the peak is not present at all or even if the peak is present, the amount is 4.8 to 5.1 ppm. It is good that it is 1/30 or less of the peak area derived from the methine proton at position 1 of cyclodextrin.

As a polyrotaxane in which the cyclic molecule has a group represented by —SiR ¹¹ _m (OR ¹² ) _3-m , more specifically, the cyclic molecule is represented by the following formula I
(Wherein X ¹¹ is a linear or branched alkylene group having 1 to 20 carbon atoms, preferably 2 to 18 carbon atoms, more preferably 2 to 10 carbon atoms (provided that non-adjacent carbon atoms are —CO—NH—, — NH-CO-, -CO-, -CO-O-, -O-CO- may be substituted), a group represented by-(CH ₂ -CH (R ²⁵ ) -O) _n- (formula R ²⁵ represents hydrogen or a linear or branched alkyl group having 1 to 8, preferably 1 to 6, and more preferably 1 to 4 carbon atoms, and n is 1 to 50, preferably 1 to 10, And more preferably represents an integer of 1 to 3, and a divalent group selected from the group consisting of combinations thereof;
R ²¹ to R ²³ are each independently a linear or branched alkyl group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 1 to 4 carbon atoms, 3 to 20 carbon atoms, preferably 3 to 10 carbon atoms, More preferably 3 to 6 cyclic alkyl groups or optionally substituted phenyl groups)
It is good to have.
More specifically, X ¹¹ is — (CH ₂ —CH (CH ₃ ) —O) _m1 —CO—NH— (CH ₂ ) _m2 — (wherein m1 and m2 are each independently 1 to 10, Preferably, it represents a number of 1 to 5, more preferably 1 to 3, and m2 represents an integer of 1 to 20, preferably 1 to 10, and more preferably 2 to 5.

Depending on the cyclic molecule used, when a cyclic molecule having a hydroxyl group, such as α-cyclodextrin, is used, the hydroxyl group is represented by a group represented by —SiR ¹¹ _m (OR ¹² ) _3-m , The desired cyclic molecule or the desired polyrotaxane can be obtained by substituting with a group to be converted. In the case where the cyclic molecule has a hydroxyl group, the hydroxyl group may be substituted in whole or in part with a desired group.
For example, when the cyclic molecule is α-cyclodextrin and the hydroxyl group (—OH) is substituted with a group represented by —SiR ¹¹ _m (OR ¹² ) _3-m , the following preparation is performed. be able to.

First, a conventionally known polyrotaxane, for example, a polyrotaxane described in Japanese Patent No. 3475252, WO2005 / 080469, JP2011-46917, etc. is prepared.
Apart from the polyrotaxane, a compound represented by R ¹⁰¹ —SiR ¹¹ _m (OR ¹² ) _3-m is prepared. Here, R ¹¹ , R ¹² and m have the same definition as described above. R ¹⁰¹ has —N═C═O group, epoxy group, —CO—X ¹ , —X ¹ , —COOH, —CO—OR ¹⁰² (R ¹⁰² is an electron-withdrawing substituent), —SO— A group having X ¹ , —SO ₂ —X ¹ (in the above, X ¹ represents halogen) is preferable.
Next, a polyrotaxane and a compound represented by R ¹⁰¹ —SiR ¹¹ _m (OR ¹² ) _3-m are reacted in an appropriate solvent under appropriate reaction conditions, whereby a hydroxyl group (—OH) is converted to —SiR. A polyrotaxane having a cyclic molecule substituted with a group represented by ¹¹ _m (OR ¹² ) _3-m can be obtained, but is not limited to these methods.

<< Cyclic molecule >>
The cyclic molecule is not particularly limited as long as it is cyclic, has an opening, and is included in a skewered manner by a linear molecule.
As described above, the cyclic molecule may have a group represented by —SiR ¹¹ _m (OR ¹² ) _3-m and may have other groups.
The cyclic molecule may be selected from the group consisting of α-cyclodextrin, β-cyclodextrin and γ-cyclodextrin, for example.
In the case where the cyclic molecule has a group represented by —SiR ¹¹ _m (OR ¹² ) _3-m and / or other groups, a cyclic molecule, for example, a hydroxyl group (—OH) of α-cyclodextrin is represented by —SiR It may be formed by substitution with a group represented by ¹¹ _m (OR ¹² ) _3-m and / or other groups. The method is as described above.

<< Linear molecule >>
The linear molecule of the polyrotaxane of the present invention is not particularly limited as long as it can be included in a skewered manner in the opening of the cyclic molecule to be used.
For example, as linear molecules, polyvinyl alcohol, polyvinyl pyrrolidone, poly (meth) acrylic acid, cellulosic resins (carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, etc.), polyacrylamide, polyethylene oxide, polyethylene glycol, polypropylene glycol, polyvinyl Polyolefin resins such as acetal resins, polyvinyl methyl ether, polyamines, polyethyleneimine, casein, gelatin, starch, and / or copolymers thereof, polyethylene, polypropylene, and copolymers of other olefin monomers; Polyester resins, polyvinyl chloride resins, polystyrene resins such as polystyrene and acrylonitrile-styrene copolymer resins, polymethyl Acrylic resin such as tacrylate, (meth) acrylic acid ester copolymer, acrylonitrile-methyl acrylate copolymer resin, polycarbonate resin, polyurethane resin, vinyl chloride-vinyl acetate copolymer resin, polyvinyl butyral resin, etc .; and derivatives or Modified products, polyisobutylene, polytetrahydrofuran, polyaniline, acrylonitrile-butadiene-styrene copolymer (ABS resin), polyamides such as nylon, polyimides, polydienes such as polyisoprene and polybutadiene, polysiloxanes such as polydimethylsiloxane , Polysulfones, polyimines, polyacetic anhydrides, polyureas, polysulfides, polyphosphazenes, polyketones, polyphenylenes, polyhaloolefins, and It may be selected from the group consisting of these derivatives. For example, it may be selected from the group consisting of polyethylene glycol, polyisoprene, polyisobutylene, polybutadiene, polypropylene glycol, polytetrahydrofuran, polydimethylsiloxane, polyethylene, polypropylene, polyvinyl alcohol and polyvinyl methyl ether. Particularly preferred is polyethylene glycol.

The linear molecule may have a weight average molecular weight of 3,000 to 500,000, preferably 5,000 to 100,000, more preferably 10,000 to 50,000.
In addition, the weight average molecular weight of a linear molecule | numerator can be measured by a gel permeation chromatography (Gel Permeation Chromatography, GPC). GPC measurement conditions depend on the type of linear molecule, but the type of eluent, column, temperature, and standard substance should be appropriately selected.
In the polyrotaxane of the present application, the combination of (cyclic molecule, linear molecule) is preferably (derived from α-cyclodextrin, derived from polyethylene glycol).

<< Blocking group >>
The blocking group is not particularly limited as long as it is a group that is arranged at both ends of the pseudopolyrotaxane and acts so that the cyclic molecule to be used does not leave.
For example, as a blocking group, dinitrophenyl groups, cyclodextrins, adamantane groups, trityl groups, fluoresceins, silsesquioxanes, pyrenes, substituted benzenes (substituents are alkyl, alkyloxy, hydroxy, Examples include, but are not limited to, halogen, cyano, sulfonyl, carboxyl, amino, phenyl, etc. One or more substituents may be present), optionally substituted polynuclear aromatics (substituted) Examples of the group include, but are not limited to, the same as described above, and one or more substituents may be present.) And a group consisting of steroids. It is preferably selected from the group consisting of dinitrophenyl groups, cyclodextrins, adamantane groups, trityl groups, fluoresceins, silsesquioxanes, and pyrenes, more preferably adamantane groups or cyclodextrins. It should be similar.

<< Amount of component (a) and component (b) >>
Component (a) and component (b) are those in which sol (a): component (b) is 99.9: 0.1-50: 50, preferably 99: 1-80: 20, more preferably It may be present in an amount of 99: 1 to 90: 5.
Further, in the gel, particularly in the aerogel, the proportion of the weight of the component (b), that is, the proportion of weight reduction up to 500 ° C. by thermogravimetric analysis is 50% or less, preferably 20% or less, more preferably 10% or less. There should be.

<< Other components in sol >>
As described above, the sol of the present invention includes the component (a) and the component (b), and may include other components other than the component (a) and the component (b).
Examples of other components include components that impart desired properties to the sol and / or gel, depending on the affinity with the obtained sol and / or the obtained gel. Examples of the component include metal alkoxides other than the component (a) or analogs thereof, high elastic polymers, high impact polymers, polymer nanocomposites, electrically conductive molecules, plasticizers, crosslinking agents, and the like. It is not limited to these.
The metal alkoxide or its analogs other than components ^(a), may be mentioned ^{MxR 111 y (OR 112) z} . Here, examples of M include, but are not limited to, Al, Ti, Zr, Zn, and W. X, y and z are natural numbers depending on the metal M. For example, when M is Al, x is 1, y + z = 3, and y is 0 to 2, preferably 0 to 1, more preferably. Should be 0. When M is Ti, x is 1, y + z = 4, and y is 0 to 3, preferably 0 to 1, and more preferably 0.
R ¹¹¹ and R ¹¹² should have the same definition as R ¹ and R ² . Specifically, R ¹¹¹ and R ¹¹² are linear or branched alkyl groups having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 1 to 4 carbon atoms, 3 to 20 carbon atoms, preferably 3 to 3 carbon atoms. It represents 10, more preferably 3 to 6 cyclic alkyl groups or an optionally substituted phenyl group.

<Method for preparing sol>
The present application provides a method for preparing the sol described above.
The preparation method is as follows:
(I) (a) preparing SiR ¹ _n (OR ² ) _4-n ;
(II) (b) a step of preparing a polyrotaxane; and (III) (a) a step of mixing SiR ¹ _n (OR ² ) _4-n and the (b) polyrotaxane and performing hydrolysis;
The above-mentioned sol is obtained by having

<Process (I)>
Step (I) is a step of preparing (a) SiR ¹ _n (OR ² ) _4-n .
The compound represented by SiR ¹ _n (OR ² ) _4-n may be a conventionally known compound or a newly synthesized compound. In the case of a conventionally known compound, it may be prepared by obtaining a commercially available product.

<Process (II)>
Step (II) is a step of preparing (b) polyrotaxane.
(B) The polyrotaxane may be a conventionally known polyrotaxane or may be obtained by newly synthesizing. In the case of a conventionally known polyrotaxane, it may be prepared by obtaining a commercially available product.
When newly synthesized, especially when the cyclic molecule has a group represented by —SiR ¹¹ _m (OR ¹² ) _3-m , a polyrotaxane can be obtained by the method described above.

<Step (III)>
Step (III) is a step in which (a) SiR ¹ _n (OR ² ) _4-n and (b) polyrotaxane are mixed and subjected to hydrolysis.
In step (III), the solvent depends on the component (a), component (b) and the like to be used, and examples thereof include a mixed solvent of N, N-dimethylformamide (DMF) and water, but are not limited thereto. Not.
Step (III) depends on the components (a) and (b) to be used, but in the presence of a base or acid, it should be carried out under temperature conditions where water does not evaporate, that is, from room temperature to 100 ° C. .

<Gel obtained from sol>
The present application provides a gel obtained from the sol described above.
The gel of the present invention may be a so-called wet gel having a solvent, a so-called dry gel having no solvent, or an aerogel. Preferably, the gel of the present invention is an airgel.

<< Mechanical properties >>
The gels of the present invention, in particular aerogels, may have one, two or more combinations of the following mechanical properties.
As mechanical properties, maximum compression strain: 10% or more, preferably 30% or more, more preferably 50% or more, most preferably 60% or more;
However, it is not limited to these.

<< Thermal conductivity >>
The gel of the present invention, particularly the airgel, has a thermal conductivity of 0.05 Wm ⁻¹ K ⁻¹ or less, preferably 0.02 Wm ⁻¹ K ⁻¹ or less, more preferably 0.015 Wm ⁻¹ K ⁻¹ or less. There should be. In particular, the airgel of the present invention preferably has the thermal conductivity in addition to the mechanical properties.
In addition, in this application, it is good to measure thermal conductivity as follows. That is, the thermal conductivity λ can be obtained according to the following equation by measuring the thermal diffusivity α and the thermal capacity C _p and measuring the bulk density ρ _b and using those values. Incidentally, the bulk density [rho _b can be measured by a density measuring instrument to apply the principle of Archimedes.

<< Transparency >>
Furthermore, the gel of the present invention, in particular the airgel, should be transparent. In particular, the airgel of the present invention should be transparent in addition to the mechanical properties and the thermal conductivity.
Here, “transparent” means, for example, that an SEM image of an airgel does not show a particle size of 100 nm or more due to growth or aggregation of silica particles.
In addition, “transparent” means that a 2 mm thick airgel transmits 60% or more, preferably 65 to 100%, more preferably 70 to 100% of light having a wavelength of 550 nm.
Specifically, the transmittance T (2) at 2 mm can be obtained by substituting the transmittance T at 550 nm at another thickness d (mm) into the following formula (X).

The gel of the present invention, particularly the airgel, has a porosity of 80% or more, preferably 85% or more, more preferably 90% or more.
In the airgel of the present invention, the porosity is determined as follows using the bulk density ρ _b and the density ρ _s of the skeleton portion other than the vacancies. Incidentally, the bulk density [rho _b can be measured by a density measuring instrument to apply the principle of Archimedes.

<Gel preparation method>
The present application provides a method for preparing the gel described above.
The preparation method is as follows:
(I) (a) preparing SiR ¹ _n (OR ² ) _4-n ;
(II) (b) a step of preparing a polyrotaxane; and (III) (a) a step of mixing SiR ¹ _n (OR ² ) _4-n and (b) polyrotaxane and performing hydrolysis to obtain a sol;
(IV) A step of adding a catalyst to the obtained sol and then allowing it to stand to prepare a wet gel;
Have
Moreover, in order to prepare an airgel, it is good to have further (V) the process of drying a wet gel.
Hereinafter, each step will be described, but steps (I) to (III) are the same as the sol preparation method, and thus the description thereof will be omitted.

<< Step (IV) >>
Step (IV) is a step of preparing a wet gel by adding a catalyst to the sol obtained in step (III) and then allowing to stand.
Here, a general acid or base used in the sol-gel method can be used as the catalyst. For example, a base such as hydroxylamine can be used, but is not limited thereto.
In addition, depending on the component (a), the component (b), etc. to be used in the standing, it is good to carry out under the conditions of 0 ° C. to 100 ° C., but is not limited thereto.

<< Step (V) >>
Step (V) is a step of drying the wet gel obtained in step (IV).
A conventionally known method can be used for this step.
Examples of conventionally known methods include, but are not limited to, a solvent replacement step in which the solvent contained in the wet gel is replaced with a solvent that is easier to dry, a supercritical drying step, and combinations thereof. Preferably, the combination of the solvent replacement step and the supercritical drying step is good, and in this case, the solvent replacement step is performed using a solvent that can be easily replaced with supercritical carbon dioxide used in the supercritical drying step, for example, a solvent such as methanol. It is good to do.
The step (V) depends on the component (a), the component (b) to be used, the solvent to be used and the like, but preferably a supercritical drying step is performed through a solvent substitution step.

The gel of the present invention, particularly the airgel, can be applied to materials that are required to have desired properties in heat insulation, transparency and mechanical strength. Examples of the material include, but are not limited to, window materials, heat insulating materials, catalysts, and particulate collection materials.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to the examples.

<Synthesis of triethoxysilyl-modified polyrotaxane>
The starting material, polyrotaxane (HAPR) (manufactured by Advanced Soft Materials), is a polyethylene glycol (PEG) having a molecular weight of 35,000 as a linear molecule, hydroxypropylated α-cyclodextrin as a cyclic molecule, and adamantane as a blocking group Has a group.
1 g of the polyrotaxane (HAPR) is dissolved in 20 ml of dehydrated DMF (N, N-dimethylformamide), and 0.2 ml of 3-isocyanatopropyltriethoxysilane (IPTS) is added dropwise thereto at room temperature. And stirred overnight. Thereafter, the resulting reaction solution was added dropwise to 200 ml of acetone to precipitate the product, and the supernatant was removed by centrifugation to collect the precipitate. This precipitate was repeatedly washed with acetone and then dried to obtain 870 mg of a triethoxysilyl-modified polyrotaxane (see the following reaction scheme).

Characterization of the triethoxysilyl modified polyrotaxane was performed by infrared spectroscopy, proton nuclear magnetic resonance, and size exclusion chromatography.
The infrared spectrum was measured using a total reflection method with a DuraSamplIR II diamond ATR accessory mounted on a NICOLET iS50 Spectrometer from Thermo Electron Co., Ltd.
The proton nuclear magnetic resonance spectrum was measured using deuterated DMSO as a solvent using JNM-AL400 manufactured by JEOL.
Size exclusion chromatography was measured at 50 ° C. using DMSO in which 10 mM LiBr was dissolved in a solvent as an eluent using a column in which two OHpak SB-804 HQs manufactured by Shodex were directly connected. A differential refraction detector was used for detection.

The FT-IR spectrum of the triethoxysilyl modified polyrotaxane is shown in FIG. In FIG. 1, absorption derived from carbonyl stretching vibration was confirmed at 1714 cm ⁻¹ which is not found in the starting polyrotaxane. From this, it was suggested that the urethane bond was formed by the reaction of the hydroxyl group of the cyclic molecule and IPTS.

^{The 1} H NMR spectrum and the assignment of each peak are shown in FIG. From the integral ratio of the methyl proton peak derived from the triethoxysilyl group appearing at 1.15 ppm and the C1H proton derived from the cyclodextrin appearing at 4.8 ppm, 2% of the hydroxyl groups possessed by the cyclic molecule of the polyrotaxane as the starting material (one cyclic molecule It was confirmed that 0.36 modification groups) were modified.
Further, since no vinyl group peak appearing at 5.8 to 6.3 ppm was observed, it was confirmed that the obtained polyrotaxane did not have a vinyl group.

A chromatogram obtained by size exclusion chromatography for the triethoxysilyl-modified polyrotaxane synthesized in Example 1 and the polyrotaxane (HAPR) which is the starting material used in Example 1 is shown in FIG.
The starting materials used in Example 1, polyrotaxane and HAPR, show a peak at an elution time of about 43 minutes, indicating that the cyclodextrin as an impurity is contained.
On the other hand, the triethoxysilyl-modified polyrotaxane synthesized in Example 1 has an elution time slightly shorter than that of the raw material polyrotaxane, which is 26 minutes, indicating no other peaks. From this, it was confirmed that the triethoxysilyl-modified polyrotaxane containing almost no uninclusion cyclodextrin (elution time: 42 minutes) contained in the degradation products and raw materials of the polyrotaxane during the reaction could be isolated. It was done.

<Synthesis of Polyrotaxane Reinforced Silica Airgel A-1>
Dissolve 23.5 mg of triethoxysilyl-modified polyrotaxane obtained in Example 1, 0.975 ml (916.5 mg) of tetraethoxysilane (TEOS), 0.3 ml of ion-exchanged water, and 0.1 ml of 14% ammonia water in 2 ml of DMF. A sol was obtained.
This sol was poured into a Teflon (registered trademark) mold and allowed to stand at room temperature for 36 hours to obtain a gel. Solvent replacement was performed by immersing the gel in ethanol, and DMF was completely removed by repeatedly immersing the gel in fresh ethanol. This gel was dried in a supercritical carbon dioxide (40 ° C., 9 MPa) atmosphere to obtain a polyrotaxane-reinforced silica airgel A-1.

(Examples 3 to 6)
<Synthesis of Polyrotaxane Reinforced Silica Airgel A-2 to A-5>
In Example 2, the amount of triethoxysilyl-modified polyrotaxane was 47 mg (Example 3), 70.5 mg (Example 4), 94 mg (Example 5), 141 mg (Example 6), and the total weight with TEOS was Polyrotaxane-reinforced silica airgels A-2 to A-5 were prepared in the same manner as in Example 1 except that the amount of TEOS was adjusted to 940 mg.

(Comparative Example 1)
<Synthesis of Silica Airgel C-1>
In Example 2, silica airgel C-1 was prepared in the same manner as in Example 1, except that the amount of triethoxysilyl-modified polyrotaxane was 0 mg and the amount of TEOS was 94 mg.
(Comparative Example 2)
<Synthesis of Silica Airgel C-2>
In Example 2, silica airgel C-1 was prepared in the same manner as in Example 1 except that the amount of triethoxysilyl-modified polyrotaxane was 470 mg and the amount of TEOS was also 470 mg.

<Quantification of polyrotaxane content in aerogels A-1 to A-5 by thermogravimetric analysis>
The weight ratio of the polyrotaxane contained in the airgels A-1 to A-5 obtained in Examples 2 to 6 was determined by thermogravimetric analysis. The measurement was performed using a Thermo Plus Evo TG8120 manufactured by Rigaku, under a nitrogen atmosphere at a heating rate of 5 ° C./min. FIG. 4 shows the change in weight with increasing temperature.
The following can be seen from FIG. That is, a significant weight reduction is observed at 300 ° C. or higher, and the weight is almost constant at 500 ° C. Thermal decomposition is derived from polyrotaxane, which is an organic substance, and the residue is considered to be silica. As a result, in Example 2 where the polyrotaxane content at the time of blending the raw materials was 2.5%, it was confirmed that the obtained airgel A-1 contained about 7% polyrotaxane.
For airgels A-2 to A-5, the amount of polyrotaxane in the airgel was measured in the same manner as airgel A-1. The results are shown in Table 1.

<< Porosity >>
The porosity was determined according to the above formula.
The bulk density ρ _b of the polyrotaxane reinforced silica airgel A-1 was 0.15 g / cm ^{3 as} determined by a density measuring device applying Archimedes' principle.
Since the ratio of the polyrotaxane in the airgel is low, the porosity ρ _s of the skeleton portion other than the vacancies was approximated by the density of amorphous silica (2.2 g / cm ³ ) to obtain the porosity. As a result, the porosity was calculated to be 93%.
For airgels A-2 to A-5 and C-1 to C-2, the porosity was determined in the same manner as airgel A-1. The results are shown in Table 1.

<< Thermal properties >>
The thermal conductivity λ was calculated from the above formula. The thermal diffusivity α was measured using ai-Phase Mobile 1u manufactured by Eye Phase Co., Ltd. Moreover, the heat capacity C _p was determined by differential scanning calorimetry using a DSC 7000X manufactured by Hitachi High-Technologies Corporation.
As a result, the thermal conductivity λ of the airgel A-1 was 0.014 Wm ⁻¹ K ⁻¹ .
As with the airgel A-1, the thermal conductivity of the airgels A-2 to A-5 and C-1 to C-2 was determined. The results are shown in Table 1.

<< Mechanical properties >>
The stress-strain behavior of the disk-shaped airgel A-1 (diameter of about 6 mm and thickness of about 8 mm) prepared in Example 2 was measured.
Measurement was performed using RSAIII manufactured by TA Instrument Co., at room temperature and a strain rate of 2 mm / min.
The airgel C-1 prepared in Comparative Example 1 containing no polyrotaxane begins to break at a compression strain of about 5%, and the stress becomes completely zero at a compression strain of 8%, whereas the airgel A prepared in Example 2 -1 was compressible to a compression strain of about 73%.
For airgels A-2 to A-3, the mechanical properties were measured in the same manner as airgel A-1. The results are shown in Table 2.

<< Transparency >>
<1. Internal structure of polyrotaxane reinforced silica airgel A-1>
The internal structure of the polyrotaxane-reinforced silica airgel A-1 obtained in Example 2 was observed with a scanning electron microscope (SEM S4800, manufactured by Hitachi). The sample was preliminarily made into a fracture surface and sputter coated with gold. The SEM image thus obtained is shown in FIG.
As can be seen from the image in FIG. 5, the skeleton portion of the airgel is formed of silica nanoparticles having a diameter of about 20 nm and hardly aggregates. Therefore, it is considered that the polyrotaxane reinforced silica airgel is hardly clouded and maintains transparency.

<2. Transmittance measurement>
The transmittances of the airgels A-1 to A-3 and C-1 obtained in Examples 1 to 3 and Comparative Example 1 were measured.
In the measurement, a sample having a thickness of about 2 mm and a length and width of about 20 mm × about 10 mm was prepared, and the transmittance of the sample at a wavelength of 550 nm was measured with an ultraviolet-visible-near infrared spectrophotometer. The transmittance T (2) at 2 mm was obtained by substituting the measured transmittance T at the thickness d (mm) of the sample into the above formula (X). The results are shown in Table 2.
From the transmittance in Table 2, the airgels A-1 to A-3 of Examples 1 to 3 have almost the same transmittance as the airgel C-1 of Comparative Example 1 that does not contain polyrotaxane, and have transparency. I understand.

Claims (14)

1. (A) SiR ¹ _n (OR ² ) _4-n
   (Wherein R ¹ and R ² each independently represents a linear or branched alkyl group having 1 to 20 carbon atoms, a cyclic alkyl group having 3 to 20 carbon atoms, or an optionally substituted phenyl group;
   n represents an integer of 0 to 3); and (b) a blocking group is provided so that the cyclic molecule is not detached at both ends of the pseudopolyrotaxane in which the opening of the cyclic molecule is skewered by the linear molecule. A polyrotaxane formed;
   A sol comprising:
2. In the (b) polyrotaxane, the cyclic molecule is —SiR ¹¹ _m (OR ¹² ) _3-m
   (Wherein R ¹¹ and R ¹² each independently represents a linear or branched alkyl group having 1 to 20 carbon atoms, a cyclic alkyl group having 3 to 20 carbon atoms, or an optionally substituted phenyl group;
   m represents an integer of 0 to 2)
   The sol according to claim 1 having a group represented by the formula:
3. In the (b) polyrotaxane, the cyclic molecule is —SiR ¹¹ _m (OR ¹² ) _3-m via a linker site.
   (Wherein R ¹¹ and R ¹² each independently represents a linear or branched alkyl group having 1 to 20 carbon atoms, a cyclic alkyl group having 3 to 20 carbon atoms, or an optionally substituted phenyl group;
   m represents an integer of 0 to 2)
   Having a group represented by
   The sol according to claim 1 or 2, wherein the linker moiety is a linear or branched alkyl group having 1 to 20 carbon atoms, an optionally substituted phenyl group, an ethylene glycol group or a group having a siloxane bond.
4. A gel obtained from the sol according to any one of claims 1 to 3.
5. The gel according to claim 4, wherein the gel is an aerogel.
6. The gel according to claim 4 or 5, wherein the gel is an airgel, and the maximum compressive strain of the airgel is 10% or more.
7. The gel according to any one of claims 4 to 6, wherein the gel is an airgel, and the airgel is transparent.
8. The gel according to any one of claims 4 to 7, wherein the gel is an airgel, and the porosity of the airgel is 80% or more.
9. The gel according to any one of claims 4 to 8, wherein the gel is an airgel, and the thermal conductivity of the airgel is 0.05 Wm ^-1 K ^-1 or less.
10. (A) SiR ¹ _n (OR ² ) _4-n
    (Wherein R ¹ and R ² each independently represents a linear or branched alkyl group having 1 to 20 carbon atoms, a cyclic alkyl group having 3 to 20 carbon atoms, or an optionally substituted phenyl group;
    n represents an integer of 0 to 3); and (b) a blocking group is provided so that the cyclic molecule is not detached at both ends of the pseudopolyrotaxane in which the opening of the cyclic molecule is skewered by the linear molecule. A polyrotaxane formed;
    A method for preparing a sol comprising:
    (I) a step of preparing (a) SiR ¹ _n (OR ² ) _4-n ;
    (II) preparing (b) the polyrotaxane; and (III) mixing the (a) SiR ¹ _n (OR ² ) _4-n and the (b) polyrotaxane and performing hydrolysis;
    The method as described above, wherein the sol is obtained.
11. (IV) A step of allowing the sol obtained in claim 10 to stand to prepare a wet gel;
    A method for preparing a wet gel.
12. (V) drying the wet gel obtained in claim 11;
    A method for preparing an airgel, comprising:
13. An airgel having a —Si—O—Si— bond and a group derived from a cyclic molecule, wherein the airgel has a maximum compressive strain of 10% or more.
14. A polyrotaxane in which a blocking group is arranged so that a cyclic molecule is not detached at both ends of a pseudo-polyrotaxane in which an opening of a cyclic molecule is included in a skewered manner by a linear molecule,
    The cyclic molecule is represented by the following formula I
    (In the formula, X ¹¹ represents a linear or branched alkylene group having 1 to 20 carbon atoms, provided that carbon atoms that are not adjacent to each other are —CO—NH—, —NH—CO—, —CO—, —CO—O; -, - O-CO- or substituted ^{_{with), - (CH 2 -CH (}} R 25) -O) n - group (where represented ^{by, R 25} is 1 hydrogen or carbon atoms to 8 And n represents an integer of 1 to 50), and a divalent group selected from the group consisting of combinations thereof;
    R ²¹ to R ²³ each independently represents a linear or branched alkyl group having 1 to 20 carbon atoms, a cyclic alkyl group having 3 to 20 carbon atoms, or an optionally substituted phenyl group)
    Have
    The polyrotaxane, wherein the polyrotaxane is free of vinyl group.
    

    

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