KR101870958B1 - Aerogel surface-modified with catechol-based compounds and preparation method thereof - Google Patents

Abstract

An embodiment of the present invention relates to aerogel surface-modified with a catechol-based compound and a preparation method thereof. The aerogel surface modified with an economically feasible and environmentally friendly catechol-based compound, has a wide surface arear and high porosity, and low thermal conductivity can be provided.

Description

TECHNICAL FIELD [0001] The present invention relates to an aerogel, which is surface-modified with a catechol-based compound, and a method for producing the same. BACKGROUND ART [0002]

The present invention relates to an airgel surface-modified with an economical and environmentally friendly catechol-based compound as well as a wide surface area, a high porosity and a low thermal conductivity, and a method for producing the same.

Aerogels are expected to be applied to various applications such as antireflection coatings, flat panel display panels and sensors due to their low permittivity, low thermal conductivity and high surface area characteristics.

Aerogels are prepared by removing the internal solvent from the wet gel synthesized through the sol-gel reaction of the precursor. The method of removing the solvent is divided into a method of removing the solvent at supercritical conditions and a method of removing atmospheric pressure.

In the case of removing the solvent under supercritical conditions, since the use of the solvent is limited due to the high price of the high-temperature and high-pressure process, studies on removing the solvent under atmospheric pressure have been conducted.

For example, Korean Patent Laid-Open Publication No. 2009-0053348 discloses a method for producing a nano-functional silica airgel thin film using a silylating agent such as trimethylchlorosilane (TMCS).

However, this method is dangerous because of high reactivity of the silylating agent, and there is a problem that poisonous gas is generated when it reacts. Therefore, it is required to develop a method of manufacturing aerogels using a new coating method which can improve the workability and physical properties by maintaining the skeleton of the nanostructure while maintaining the characteristics of the aerogels.

Korea Patent Publication No. 2009-0053348

When a silylating agent such as trimethylchlorosilane (TMCS) is used, the expensive silylating agent is used in an excess amount, and since chlorine gas and corresponding corrosion are generated during the surface modification, There is an additional cost and a problem that the side reaction rate is high (see Korean Patent Publication No. 2009-0053348).

Accordingly, an object of the present invention is to provide an aerogel which is surface-modified with a catechol-based compound which can be synthesized under atmospheric pressure, is economical and environmentally friendly, has a wide surface area, high porosity and low thermal conductivity, and a method for producing the same.

In order to achieve the above object,

The present invention provides an aerogels surface-modified with catechol-based compounds.

Further, in one embodiment,

A method for producing an airgel surface-modified with the catechol-based compound,

Preparing a wet gel using a sol-gel reaction of a nanoskeleton precursor;

Mixing the wet gel with a polar solvent to replace the solvent in the wet gel with the polar solvent;

Modifying the surface of the nano-scaffold by mixing the wet gel substituted with the polar solvent and the catechol-based compound;

Washing the surface-modified wet gel with a first organic solvent;

Replacing the solvent in the washed wet gel with a second organic solvent; And

And drying the wet gel substituted with the second organic solvent at 0 to 200 ° C.

A method for producing an aerogel surface-modified with a catechol-based compound.

Aerogels surface-modified with catechol-based compounds according to the embodiments are environmentally friendly, have a large surface area, a high porosity and a low thermal conductivity.

In addition, the production cost can be lowered by using a relatively inexpensive catechol-based compound.

Further, according to the method for producing an aerogel surface-modified with the catechol-based compound according to the embodiment, it is possible to produce aerogels safely and economically because it can be synthesized under normal pressure conditions.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a SEM photograph of silica aerogels surface-modified with urushiol prepared in Example 1. FIG.
2 is an SEM photograph of the silica airgel surface-modified with the TBC prepared in Example 2. Fig.
3 is a SEM photograph of silica airgel surface-modified with dopamine and TBC prepared in Example 3. Fig.
4 is a SEM photograph of silica airgel surface-modified with dopamine, TBC and hexylamine prepared in Example 4. Fig.

Embodiments provide aerogels surface-modified with catechol-based compounds and methods of making the same.

[Airgel]

The airgel according to one embodiment is characterized by being an airgel surface-modified with a catechol-based compound.

The surface of the modified aerogels is hydrophobic.

The catechol-based compound is a compound having a catechol group, and includes catechol and derivatives thereof.

The catechol group means a group in which a hydroxyl group (-OH) is substituted at an ortho position of a benzene ring. For example, the catechol group may be a 1,2-dihydroxybenzene group.

Specifically, the catechol-based compound is selected from the group consisting of catechol, 4-tert-butylcatechol (TBC), urushiol, dopamine, alizarin, tannic acid, It includes at least one member selected from the group consisting of pyrogallol, gallic acid, epigallocatechin, epicatechin gallate, and epigallocatechin gallate But is not limited thereto.

When the surface of the aerogels becomes hydrophobic by modifying the surface of the aerogels with the catechol-based compound, the structure of the nanoscale structure is maintained at the time of normal-pressure drying, so that a high porosity, low density and low thermal conductivity are obtained.

The aerogels include at least one selected from the group consisting of silica, titania and alumina. For example, the aerogels may be silica aerogels, but are not limited thereto.

The airgel surface-modified with the catechol-based compound is a porous material and has a reticular skeleton structure.

The surface area of the aerogels is 300 to 1,500 m ² / g. Specifically, the surface area of the aerogels is 300 to 1,200 m ² / g. More specifically, the surface area of the aerogels may be 300 to 1,000 m ² / g, but is not limited thereto.

When the surface area of the aerogels is in the above range, it is advantageous to exhibit the effects of high porosity, low density and low thermal conductivity.

The volume of the air gap formed in the airgel is 0.01 to 10 cm ³ / g. Specifically, the volume of the air gap formed in the airgel may be 0.1 to 5 cm ³ / g, but is not limited thereto.

When the volume of the air gap formed in the airgel is within the above range, it is advantageous to exhibit the effects of high porosity, low density and low thermal conductivity.

The average diameter of the pores formed in the aerogels is 12 to 100 nm. Specifically, the average diameter of the voids formed in the airgel is 12 to 70 nm. More specifically, the average diameter of the pores formed in the airgel may be from 12 to 50 nm, but is not limited thereto.

When the average diameter of the air gaps formed in the airgel is within the above range, it is advantageous to exhibit the effects of high porosity, low density and low thermal conductivity.

When the volume and the average diameter of the air gaps formed in the airgel are in the respective ranges, the porosity of the airgel is at least 60%. Specifically, the porosity of the airgel may be 70% or more, but is not limited thereto.

When the porosity of the airgel is 60% or more, it is advantageous to exhibit the effect of low density and low thermal conductivity.

The airgel has a thermal conductivity of 15 to 65 mW / m · K. Specifically, the airgel has a thermal conductivity of 15 to 60 mW / m · K. More specifically, the thermal conductivity of the airgel may be 15 to 50 mW / m · K, but is not limited thereto.

When the thermal conductivity of the airgel is within the above range, it is advantageous to exhibit an excellent heat insulating effect.

[Method of manufacturing airgel]

In one embodiment, a method for preparing an airgel surface-modified with a catechol-based compound as described above comprises the steps of: preparing a wet gel using a sol-gel reaction of a nanobase precursor; Mixing the wet gel with a polar solvent to replace the solvent in the wet gel with the polar solvent; Modifying the surface of the nano-scaffold by mixing the wet gel substituted with the polar solvent and the catechol-based compound; Washing the surface-modified wet gel with a first organic solvent; Replacing the solvent in the washed wet gel with a second organic solvent; And drying the wet gel substituted with the second organic solvent at 0 to 200 캜.

First, a wet gel is prepared using the sol-gel reaction of the nanoblock precursor. At this time, it may include aging the solution containing the nanobase precursor at 25 to 60 DEG C for 6 to 48 hours. This is a step of synthesizing a wet gel having a reticular skeleton structure by using the sol-gel reaction of the nanoblock precursor.

The sol-gel reaction is performed by hydrolysis of a metal alkoxide precursor by a catalyst, condensation and agglomeration of the grown particles, and a gel having a porous skeletal structure is formed through aging.

Next, the wet gel and the polar solvent are mixed to replace the solvent in the wet gel with the polar solvent. This is a step for treating the catechol surface, removing the residual precursor and the catalyst, and replacing the inside and the outside of the gel with the solvent condition for the surface treatment.

The polar solvent is a polar protic solvent or a polar aprotic solvent.

Specifically, the polar protic solvent may include at least one selected from the group consisting of water, ethanol, methanol and isopropanol, but is not limited thereto.

The polar aprotic solvent may be selected from the group consisting of acetone, propylene glycol monomethyl ether acetate (PGMEA), tetrahydrofuran (THF), ethyl acetate, chloroform, methylene chloride, dimethylformamide and dimethyl sulfoxide DMSO), but the present invention is not limited thereto.

Subsequently, the wet gel substituted with the polar solvent and the catechol-based compound are mixed to modify the surface of the nano-scaffold. This is a step in which the surface of the wet gel having a reticular skeleton structure is modified with a catechol-based compound. At this time, the surface of the modified aerogels becomes hydrophobic.

The catechol-based compound may be added in an amount of 0.005 to 5 mmol / ml. Specifically, it may be added in an amount of 0.01 to 2 mmol / ml.

When the content of the catechol-based compound is in the above range, the surface of the porous airgel exhibits hydrophobicity and exhibits an effect of increasing physical strength.

When the catechol-based compound is added, an amine-based compound may be added together. Specifically, the amine-based compound may include at least one selected from the group consisting of a primary amine-based compound and a diamine-based compound, but is not limited thereto.

More specifically, the amine-based compounds may be selected from the group consisting of hexylamine, 1-octylamine, dodecylamine, hexadecylamine, octadecylamine, oleylamine, trioxylamine, But are not limited to, at least one selected from the group consisting of 4,7,10-trioxa-1,13-tridecanediamine and hexamethylenediamine.

When an amine-based compound is added to the catechol-based compound, it is advantageous to form a hydrophobic thin modified film and increase the durability of the modified film by polymerizing the catechol-based compound.

Next, the surface-modified wet gel is washed with a first organic solvent. This is a step for removing unreacted modifier and other organic substances.

The first organic solvent may be at least one selected from the group consisting of ethanol, propylene glycol monomethyl ether acetate (PGMEA), tetrahydrofuran (THF), acetone, ethyl acetate, isopropanol, methanol, chloroform, methylene chloride, dimethylformamide, Dimethyl sulfoxide (DMSO), and the like, but the present invention is not limited thereto.

Subsequently, the solvent in the washed wet gel is replaced with a second organic solvent. This is to minimize the shrinkage of the skeleton due to the capillary pressure during the normal-pressure drying by replacing the solvent in the wetting gel with the second organic solvent having a low surface tension.

The second organic solvent is an organic solvent having a low surface tension. Specifically, the surface tension of the second organic solvent may be 50 dyn / cm or less. More specifically, the surface tension of the second organic solvent may be 10 to 35 dyn / cm. More specifically, the surface tension of the second organic solvent may be 10 to 20 dyn / cm.

When the surface tension of the second organic solvent is in the above range, it is advantageous to minimize the shrinkage of the skeleton due to the capillary pressure during the normal-pressure drying.

For example, the second organic solvent may include at least one selected from the group consisting of hexane, pentane, heptane, isopropanol, chloroform, methylene chloride, ether, acetone and tetrahydrofuran (THF) It is not.

Finally, by drying the washed wet gel at 0 to 200 ° C, an airgel surface-modified with a catechol-based compound can be produced.

According to the above-described method for producing aerogels, since the catechol-based compound which can be synthesized under atmospheric pressure and relatively inexpensive catechol-based compound is used, the cost can be reduced and it can be safely produced. In addition, since catechol-based compounds are used, it is possible to produce environmentally friendly aerogels.

In the above-described method for producing an aerogel, the nanoblock precursor includes at least _one selected from the group consisting of a compound having a C ₁ -C ₂₀ alkoxy group and sodium silicate.

For example, the nanoscale precursor may be selected from the group consisting of tetramethylorthosilicate (TMOS), tetraethyl orthosilicate (TEOS), titanium tetraisopropoxide (TTIP), titanium tetrabutoxide But is not limited to, at least one selected from the group consisting of titanium tetrabutoxide, aluminum tri-sec-butoxide and sodium silicate.

In the above-described method of producing an aerogel, the description of the catechol-based compound is the same as that of the "catechol-based compound"

In the above-described method for producing an aerogel, the description of the constituents of the aerogels, the surface area, the volume of the pores formed in the airgel, the average diameter of the pores formed in the aerogels, the porosity of the airgel and the thermal conductivity are described in the above- do.

The above contents will be described in more detail by the following examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the examples.

[ Example ]

Example  1: surface with urushiol Reformed  Manufacture of silica airgel

4.7 g of tetraethyl orthosilicate (TEOS), 10 ml of ethanol, 1.3 ml of water and 2.8 36 of 36% hydrochloric acid were mixed and hydrolyzed for 10 minutes, followed by addition of 9.3 30 of 30% ammonium hydroxide , A wet gel was prepared. The wet gel was aged at 50 캜 for 48 hours, disrupted, and then washed with a small amount of ethanol. The wet gel was mixed with propylene glycol monomethyl ether acetate (PGMEA), and the solvent in the wet gel was replaced with PGMEA. The wet gel substituted with PGMEA was modified in the surface of the nano-scaffold for 24 hours in 20 ml of a mixed solution of urushiol and PGMEA. The surface-modified wet gel was washed with PGMEA and heat-treated at 100 占 폚 for 12 hours. The solvent in the wet gel was replaced with hexane and dried at 60 DEG C to prepare a surface modified silica airgel.

Example  2: surface with TBC Reformed  Manufacture of silica airgel

4.7 g of TEOS, 10 ml of ethanol, 1.3 ml of water and 2.8 36 of 36% hydrochloric acid were mixed and hydrolyzed for 10 minutes, and then 9.3 30 of 30% ammonium hydroxide was added to prepare a wet gel. The wet gel was aged at 50 캜 for 48 hours, disrupted, and then washed with a small amount of ethanol. The wet gel and PGMEA were mixed to replace the solvent in the wet gel with PGMEA. The wet gel substituted with PGMEA was modified in the surface of the nano-scaffold for 24 hours in 20 ml of a mixed solution of TBC and PGMEA at pH 8. The surface modified wet gel was washed with PGMEA and the solvent in the washed wet gel was replaced with hexane. Thereafter, it was dried at 60 DEG C to prepare a surface-modified silica airgel.

Example  3: Surface with dopamine and TBC Reformed  Manufacture of silica airgel

6.6 ml of a sodium silicate solution having a silica content of 5% by weight and 3.3 ㎕ of hydrochloric acid of 1.15 M as an acid catalyst were mixed and aged at 50 캜 for 48 hours to prepare a wet gel. After the wetting gel was crushed, it was mixed with water to replace the solvent in the wetting gel with water. The water-substituted wet gel was placed in 40 ml of ethanol containing 4 mg of dopamine and 3.5 mg of TBC, and the surface was reformed for 12 hours. The surface-modified wet gel was washed with ethanol. The solvent in the wet gel was replaced with isopropanol and hexane. Thereafter, it was dried at 60 DEG C to prepare a surface-modified silica airgel.

Example  4: dopamine, TBC and With hexylamine  surface Reformed  Manufacture of silica airgel

6.6 ml of a sodium silicate solution having a silica content of 5% by weight and 3.3 ㎕ of hydrochloric acid of 1.15 M as an acid catalyst were mixed and aged at 50 캜 for 48 hours to prepare a wet gel. After the wetting gel was crushed, it was mixed with water to replace the solvent in the wetting gel with water. The water-substituted wet gel was placed in a mixed solution of 1.3 ml of dopamine and 5.8 mg of TBC in 40 ml of ethanol and 0.11 ml of hexylamine, and the surface was reformed for 12 hours. The surface-modified wet gel was washed with ethanol. The solvent in the wet gel was replaced with isopropanol and hexane. Thereafter, it was dried at 60 DEG C to prepare a surface-modified silica airgel.

Comparative Example  1: Surface with catechol compound Not reformed  Manufacture of non-silica airgel

6.6 ml of a sodium silicate solution having a silica content of 5% by weight and 3.3 ㎕ of hydrochloric acid of 1.15 M as an acid catalyst were mixed and aged at 50 캜 for 48 hours to prepare a wet gel. After the wetting gel was crushed, it was mixed with water to replace the solvent in the wetting gel with water. The surface-modified wet gel was washed with ethanol. In addition, isopropanol and hexane were used to replace the solvent in the wet gel. Thereafter, it was dried at 60 DEG C to prepare an airgel.

Evaluation example  1: surface area of aerogels

The surface area of the aerogels prepared in Examples 1 to 4 and Comparative Example 1 was measured by a BET (Brunauer, Emmett and Teller) measurement method. The results are shown in Table 1 below.

Evaluation example  2: volume of air gap formed in airgel

The volume of pores formed in the aerogels manufactured in Examples 1 to 4 and Comparative Example 1 was measured by a BET measurement method. The results are shown in Table 1 below.

Evaluation example  3: Average of voids formed in airgel diameter

The average diameter of pores formed in the aerogels prepared in Examples 1 to 4 and Comparative Example 1 was measured by a BET measurement method. The results are shown in Table 1 below.

Evaluation example  4: Thermal conductivity of aerogels

The thermal conductivity of the airgel prepared in Example 4 and Comparative Example 1 was measured by a modified Transient Plane Source Method (C-Therm Thermal Conductivity Analyzer). The results are shown in Table 1 below.

Evaluation example 1 Evaluation example 2 Evaluation example 3 Evaluation example 4 Surface area
(m ² / g) Volume of pore
(cm < ³ > / g) Average diameter of pores
(nm) Thermal conductivity
(mW / mK) Example 1 697 2.17 12.47 - Example 2 523 2.35 18.0 - Example 3 369 2.2 23.87 - Example 4 377 1.93 20.51 48.5 Comparative Example 1 290 1.00 11.8 65.6

As shown in Table 1, it can be seen that Examples 1 to 4 have a larger surface area, a larger volume of pores, a longer average diameter of pores, a higher porosity and a higher thermal conductivity as compared with Comparative Example 1.

1 to 4 showing SEM photographs of Examples 1 to 4, surface-modified aerogels having voids can be identified.

Claims (18)

delete delete delete delete delete delete delete A method for producing an airgel surface-modified with a catechol-based compound,
Preparing a wet gel using a sol-gel reaction of a nanoskeleton precursor;
Mixing the wet gel with a polar solvent to replace the solvent in the wet gel with the polar solvent;
Modifying the surface of the nano-scaffold by mixing the wet gel substituted with the polar solvent and the catechol-based compound;
Washing the surface-modified wet gel with a first organic solvent;
Replacing the solvent in the washed wet gel with a second organic solvent; And
And drying the wet gel substituted with the second organic solvent at 0 to 200 ° C.
A method for producing an aerogels surface-modified with a catechol-based compound.
9. The method of claim 8,
Wherein the nanoscale precursor comprises at least one member selected from the group consisting of a compound having a C ₁ -C ₂₀ alkoxy group and sodium silicate.
9. The method of claim 8,
The nanoscale precursor may be selected from the group consisting of tetramethyl orthosilicate (TMOS), tetraethylorthosilicate (TEOS), titanium tetraisopropoxide (TTIP), titanium tetrabutoxide , Aluminum tri-sec-butoxide, and sodium silicate. ≪ RTI ID = 0.0 >
A method for producing an aerogels surface-modified with a catechol-based compound.
9. The method of claim 8,
Wherein the polar solvent is a polar protic solvent or a polar aprotic solvent,
Wherein the polar protic solvent comprises at least one member selected from the group consisting of water, ethanol, methanol and isopropanol,
The polar aprotic solvent may be selected from the group consisting of acetone, propylene glycol monomethyl ether acetate (PGMEA), tetrahydrofuran (THF), ethyl acetate, chloroform, methylene chloride, dimethylformamide and dimethylsulfoxide (DMSO) ≪ RTI ID = 0.0 > and / or < / RTI >
A method for producing an aerogels surface-modified with a catechol-based compound.
9. The method of claim 8,
Wherein the catechol-based compound is a compound comprising a catechol group.
9. The method of claim 8,
Wherein the catechol-based compound is selected from the group consisting of catechol, 4-tert-butylcatechol (TBC), urushiol, dopamine, alizarin, tannic acid, pyrogallol which comprises at least one member selected from the group consisting of pyrogallol, gallic acid, epigallocatechin, epicatechin gallate and epigallocatechin gallate. Way.
9. The method of claim 8,
Wherein the first organic solvent is selected from the group consisting of ethanol, propylene glycol monomethyl ether acetate (PGMEA), tetrahydrofuran (THF), acetone, ethyl acetate, isopropanol, methanol, chloroform, methylene chloride, dimethylformamide, Sulfoxide (DMSO). ≪ RTI ID = 0.0 >
A method for producing an aerogels surface-modified with a catechol-based compound.
9. The method of claim 8,
Wherein the second organic solvent has a surface tension of 50 dyn / cm or less,
A method for producing an aerogels surface-modified with a catechol-based compound.
16. The method of claim 15,
Wherein the second organic solvent comprises at least one selected from the group consisting of hexane, pentane, heptane, isopropanol, chloroform, methylene chloride, ether, acetone and tetrahydrofuran (THF)
A method for producing an aerogels surface-modified with a catechol-based compound.
9. The method of claim 8,
Wherein the aerogels have a surface area of 300 to 1,500 m < ² > / g,
A method for producing an aerogels surface-modified with a catechol-based compound.
9. The method of claim 8,
Wherein an average diameter of voids formed in the airgel is 12 to 100 nm,
A method for producing an aerogels surface-modified with a catechol-based compound.

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