WO2008068873A1

WO2008068873A1 - Monolayer nanoparticle film, multilayer nanoparticle film, and manufacturing method thereof

Info

Publication number: WO2008068873A1
Application number: PCT/JP2006/324986
Authority: WO
Inventors: Kazufumi Ogawa
Original assignee: Kazufumi Ogawa
Priority date: 2006-12-08
Filing date: 2006-12-08
Publication date: 2008-06-12

Abstract

Monolayer nanoparticle films, multilayer nanoparticle films, and manufacturing method thereof. The nanoparticle films include films of inorganic nanoparticles including metals or metal oxides, polymer or polymeric micelles, or organic-inorganic hybrid nanoparticles that are provided with thermal reactivity, photo reactivity, radical reactivity, or ion reactivity to surfaces thereof.

Description

DESCRIPTION

MONOLAYER NANOPARTICLE FILM, MULTILAYER NANOPARTICLE FILM, AND

MANUFACTURING METHOD THEREOF

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a nanoparticle-laminated film. More particularly, the present invention relates to a laminated film of inorganic nanoparticles including metals or metal oxides, polymer or polymeric micelles, or organic-inorganic hybrid nanoparticles that are provided with thermal reactivity, photo reactivity, radical reactivity, or ion reactivity to surfaces thereof.

The term "inorganic nanoparticles," as used in the embodiments disclosed herein includes conductive nanoparticles, semiconductor nanoparticles, insulating nanoparticles, magnetic nanoparticles, fluorescent nanoparticles, light absorbing nanoparticles, light transmitting nanoparticles, and pigment nanoparticies. The term

"organic nanoparticles," includes organic fluorescent nanoparticles, organic light absorbing nanoparticles, organic light transmitting nanoparticles, organic pigment nanoparticles, and drug nanoparticles. The term "organic-inorganic hybrid nanoparticles," includes drug nanoparticles for DDS (Drug Delivery System), cosmetic nanoparticles, and organic-inorganic hybrid pigment nanoparticles.

Description of Related Art

Conventionally, Langmuir-Blodgett (LB) technique is known in which amphiphilic organic molecules are used to build up monomolecular films on a substrate surface by depositing the molecules on a water surface. Also, a chemical absorption (CA) technique is known in which monomolecular films are built up by using a chemical absorption technique in a solution that contains a surfactant therein.

However, a coating film containing nanoparticles which are laid out in one layer and having a uniform thickness on the order of particle size on a substrate surface (hereinafter, referred to as a monolayer nanoparticle film), or a coating film in which a plurality of layers are built up and each layer is a film containing nanoparticles that are laid out in one layer on a substrate surface (hereinafter, referred to as a multilayer nanoparticle film), and a manufactured method thereof have not been developed or provided yet.

Under the prior art, a number of micron-sized or nano-sized fine particles having various functions such as an electrical function, a magnetic function, and an optical function have been developed and manufactured. In order to effectively use such inherent functions of the nanoparticles, the nanoparticles should be contained in a coating film having a uniform film thickness, however, so far, there has not been a concept yet for manufacturing a coating film having a uniform film thickness on the order of particle size using nanoparticles. Accordingly, it would be advantageous to provide a coating film containing nanoparticles which are laid out in one layer and having a uniform thickness on the order of particle size on a substrate surface (monolayer nanoparticle film), or a coating film in which a plurality of layers are built up and each layer is a film containing nanoparticles which are laid out in one layer on a substrate surface (multilayer nanoparticle film), and a manufactured method thereof, using the nanoparticles without damaging the various inherent functions of the nanoparticles.

SUMMARY OF THE INVENTION In accordance with aspects of the invention, a monolayer nanoparticle film is provided, characterized in that one layer of nanoparticles that is formed on a substrate surface is covalently bound to a first organic film formed on the substrate surface via a second organic films formed on nanoparticle surfaces. In accordance with further aspects, multilayer nanoparticle films are disclosed. According to yet further aspects of the invention, methods for manufacturing the monolayer nanoparticle film and multilayer nanoparticle films are also disclosed. The monolayer nanoparticle film and multilayer nanoparticle films maintain characteristics of the nanoparticles from which they are formed.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified:

Fig. 1A to 1C are enlarged conceptual diagrams showing a reaction at a molecule nanoparticle surface at a molecule level in a first example of the present invention, with Fig. 1A showing a nanoparticle surface before a reaction, Fig. 1B showing a nanoparticle surface after a monomolecular film containing epoxy groups is formed thereon, and Fig. 1C showing a nanoparticle surface after a monomolecular film containing amino groups is formed thereon;

Fig. 2A to 2C are enlarged conceptual diagrams showing a reaction at a molecule nanoparticle surface at a molecule level in a second example of the present invention, with Fig. 2A showing a nanoparticle surface before a reaction, Fig. 2B showing a nanoparticle surface after a monomolecular film containing epoxy groups is formed thereon, and Fig. 2C showing a nanoparticle surface after a monomolecular film containing amino groups is formed thereon; and Fig. 3A and 3B are enlarged conceptual diagrams showing a reaction at a glass substrate surface at a molecule level in a third and forth example of the present invention, with Fig. 3A showing a substrate surface after a monolayer nanoparticle film is formed thereon, and Fig. 3B showing a nanoparticle surface after two monolayer nanoparticle film are formed thereon.

DETAILED DESCRIPTION

Embodiments of monolayer nanoparticle film, multilayer nanoparticle film, and manufacturing method thereof are described herein. In the following description, numerous specific details are set forth to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention. In accordance with aspects of the invention, a monolayer nanoparticle film is provided, characterized in that one layer of nanoparticles that is formed on a substrate surface is covalently bound to a first organic film, which is formed onto the substrate surface via second organic films which are formed onto nanoparticle surfaces. In accordance with one method of manufacture, the monolayer nanoparticle film are manufactured by: forming a first reactive organic film on the substrate surface by contacting the substrate surface with a chemical adsorbent solution, which is made by mixing at least a first alkoxysilane compound, a silanol condensation catalyst, and a non-aqueous organic solvent to cause the substrate surface to react with the alkoxysilane compound; forming second reactive organic films on nanoparticle surfaces by dispersing the nanoparticles into a chemical adsorbent solution, which is made by mixing at least a second alkoxysilane compound, a silanol condensation catalyst, and a non-aqueous organic solvent to cause the nanoparticle surfaces to react with the alkoxysilane compound; contacting the substrate surface having the first reactive organic film formed thereon with the nanoparticles covered with the second reactive organic films to cause the first reactive organic film and the second reactive organic film to react with each other; and cleaning and removing excess nanoparticles covered with the second reactive organic films.

In the manufacturing, after the step for forming a first reactive organic film on a substrate surface by contacting the substrate surface with a chemical adsorbent solution which is made by mixing at least a first alkoxysilane compound, a silanol condensation catalyst, and a non-aqueous organic solvent to cause the substrate surface to react with the alkoxysilane compound, and the step for forming a second reactive organic film on nanoparticle surfaces by dispersing the nanoparticles into a chemical adsorbent solution which is made by mixing at least a second alkoxysilane compound, a silanol condensation catalyst, and a non-aqueous organic solvent to cause the nanoparticle surfaces to react with the alkoxysilane compound, the substrate and the nanoparticle surface are cleaned with an organic solvent respectively to form a first reactive monomolecular film on the substrate and second reactive monomolecular films on the nanoparticle surfaces which are covalently bound to each other. This provides an advantage in facilitating a control of a film thickness of the monolayer nanoparticle film.

The first reactive organic film contains epoxy groups and the second reactive organic film contains imino groups, or the first reactive organic film contains imino groups and the second reactive organic film contains epoxy groups. This provides an advantage in manufacturing a monolayer nanoparticle film, which is covalently bound to the substrate surface. Also, the first reactive monomolecular film contains epoxy groups and the second reactive monomolecular film contains imino groups, or the first reactive monomolecular film contains imino groups and the second reactive monomolecular film contains epoxy groups. This provides an advantage in manufacturing a monolayer nanoparticle film, which is covalently bound to the substrate surface.

Moreover, a ketimine compound, organic acid, aldimine compound, enamine compound, oxazolidine compound, or an aminoalkyl alkoxysilane compound may be used instead of the silanol condensation catalyst. This provides an advantage in reducing the time for manufacturing a film. Also, at least one selected from the group consisting of a ketimine compound, an organic acid, an aldimine compound, an enamine compound, an oxazolidine compound, and an aminoalkyl alkoxysilane compound may be mixed into the silanol condensation catalyst as a promoter. This provides an advantage in further reducing the time for manufacturing a film.

The first organic coating film formed on nanoparticle surfaces may be different from the second organic film formed on the substrate surface, which provides an advantage in causing only one layer of the monolayer nanoparticle film to be bound to the substrate surface. Also, a use of an NC bonding which is formed by a reaction between epoxy groups and imino groups as a covalent bonding provides an advantage in providing a monolayer nanoparticle film having high adhesion strength to the substrate. Both the first organic coating film formed on nanoparticle surfaces and the second organic film formed on a substrate surface are monomolecular film, which provides an advantage in enhancing uniformity of film thickness.

Moreover, this embodiment can be summarized as follows: it provides a multilayer nanoparticle film, characterized in that it is accumulated in layers on a substrate surface, and nanoparticles having organic coating films on the surfaces thereof are covalently bound to each other via the organic coating films across the layers, the multilayer nanoparticle film being manufactured by: a step for forming a first reactive organic film on a substrate surface by contacting the substrate surface with a chemical adsorbent solution which is made by mixing at least a first alkoxysilane compound, a silanol condensation catalyst, and a non-aqueous organic solvent to cause the substrate surface to react with the alkoxysilane compound; a step for forming a second reactive organic films on first nanoparticle surfaces by dispersing first nanoparticles into a chemical adsorbent solution which is made by mixing at least a second alkoxysilane compound, a silanol condensation catalyst, and a non-aqueous organic solvent to cause the first nanoparticle surfaces to react with the alkoxysilane compound; a step for contacting the substrate surface having the first reactive organic film formed thereon with the first nanoparticles which are covered with the second reactive organic films to cause the first reactive organic film and the second reactive organic films to react with each other; a step for forming a first monolayer nanoparticle film by cleaning and removing excess first nanoparticles covered with the second reactive organic films; a step for forming third reactive organic films on second nanoparticle surfaces by dispersing the second nanoparticles into a chemical adsorbent solution which is made by mixing at least a third alkoxysilane compound, a silanol condensation catalyst, and a non-aqueous organic solvent to cause the second nanoparticle surfaces to react with the alkoxysilane compound; a step for contacting the substrate surface having the first monolayer nanoparticle film thereon which is covered with the second reactive organic film with the second nanoparticles which are covered with the third reactive organic films to cause the second reactive organic film and the third reactive organic films to react with each other; and a step for forming a second monolayer nanoparticle film by cleaning and removing excess second nanoparticle covered with the third reactive organic films. The first reactive organic film may be identical to the third reactive organic film, which provides an advantage in making the method for manufacturing a multilayer nanoparticle film simpler.

After the step for forming second monolayer nanoparticle films, the step for forming a first monolayer nanoparticle film and the step for forming second monolayer nanoparticle films may be similarly repeated, which facilitates the manufacture of a multilayer nanoparticle film which includes a plurality of layers.

Furthermore, after the steps for forming first to third reactive organic films, first to third reactive monomolecular films may be formed by individually cleaning the substrate surface or the nanoparticle surfaces by an organic solvent, which provides an advantage in enhancing uniformity of film thickness of the multilayer nanoparticle film. The first and third reactive organic films contain epoxy groups and the second reactive organic film contains imino groups, or the first and third reactive organic films contain imino groups and the second reactive organic film contains epoxy groups, which provides an advantage in manufacturing a multilayer nanoparticle film in which layers are covalently bound to each other by a reaction between the epoxy groups and the imino groups.

Moreover, a ketimine compound, organic acid, aldimine compound, enamine compound, oxazolidine compound, or an aminoalkyl alkoxysilane compound may be used instead of the silanol condensation catalyst. This provides an advantage in reducing the time for manufacturing a film. Also, at least one selected from the group consisting of a ketimine compound, organic acid, aldimine compound, enamine compound, oxazolidine compound, and an aminoalkyl alkoxysilane compound may be mixed into the silanol condensation catalyst as a promoter. This provides an advantage in further reducing the time for manufacturing a film.

Also, there may be two kinds of organic coating films to be formed on the nanoparticle surfaces so that the nanoparticles having first organic films formed thereon and the nanoparticles having second organic films formed thereon may be alternately laminated, which provides an advantage in manufacturing a multilayer nanoparticle film that has a plurality of layers in simple processes.

A covalent bonding formed by a reaction between the first organic films and the second organic films provides an advantage in providing a multilayer nanoparticle film having high adhesion strength. Also, the use of an NC bonding which is formed by a reaction between epoxy groups and imino groups as a covalent bonding provides an advantage in providing a multilayer nanoparticle film having high strength. As described above, one embodiment of the present invention is particularly effective in that it provides a coating film containing nanoparticles which are laid out in one layer and having a uniform thickness on the order of particle size on a substrate surface (monolayer nanoparticle film), or a coating film in which a plurality of layers are built up and each layer is a film containing nanoparticles which are laid out in one layer on a substrate surface (multilayer nanoparticle film), and a manufactured method thereof, using the nanoparticles without damaging the various inherent functions of the nanoparticles at low cost.

Another embodiment provides a multilayer nanoparticle film which is accumulated in layers on a substrate surface and in which nanoparticles having organic coating films on the surfaces thereof are covalently bound to each other via the organic coating films across the layers by a manufacturing method comprising: a step for forming a first reactive organic film on a substrate surface by contacting the substrate surface with a chemical adsorbent solution which is made by mixing at least a first alkoxysilane compound, a silanol condensation catalyst, and a non-aqueous organic solvent to cause the substrate surface to react with the alkoxysilane compound; a step for forming a second reactive organic film on first nanoparticle surfaces by dispersing the first nanoparticles into a chemical adsorbent solution which is made by mixing at least a second alkoxysilane compound, a silanol condensation catalyst, and a non-aqueous organic solvent to cause the first nanoparticle surfaces to react with the alkoxysilane compound; a step for contacting the substrate surface having the first reactive organic film formed thereon with the first nanoparticles which are covered with the second reactive organic films to cause the first reactive organic film and the second reactive organic films to react with each other; a step for forming a first monolayer nanoparticle film by cleaning and removing excess first nanoparticles covered with the second reactive organic films; a step for forming third reactive organic films on second nanoparticle surfaces by dispersing the second nanoparticles into a chemical adsorbent solution which is made by mixing at least a third alkoxysilane compound, a silanol condensation catalyst, and a non-aqueous organic solvent to cause the second nanoparticle surfaces to react with the alkoxysilane compound; a step for contacting the substrate surface having the first monolayer nanoparticle film thereon which is covered with the second reactive organic film with the second nanoparticles which are covered with the third reactive organic films to cause the second reactive organic film and the third reactive organic films to react with each other; and a step for forming a second monolayer nanoparticle film by cleaning and removing excess second nanoparticles covered with the third reactive organic films.

Therefore, this embodiment has effect to provide a coating film containing nanoparticles which are laid out in one layer and having a uniform thickness on the order of particle size on a substrate surface (monolayer nanoparticle film), or a coating film in which a plurality of layers are built up and each layer is a film containing nanoparticles which are laid out in one layer on a substrate surface (multilayer nanoparticle film), and a manufactured method thereof, by using two kinds of nanoparticles which are covered with two kinds of coating films respectively, without damaging the various inherent functions of the two kinds of nanoparticles, and also provide a method for simply manufacturing the films at low cost.

Now, aspects of the invention will be explained below in detail by way of examples; however, it will be understood that these examples are merely illustrative, and not meant to be limiting. A monolayer nanoparticle film or multilayer nanoparticle film in accordance with various embodiments of the invention may include nanoparticles such as conductive particles having hydrophilic oxide or hydroxide on the surface thereof, semiconductor particles, insulating particles, magnetic particles, fluorescent particles, light absorbing particles, light transmitting particles, pigment particles, drug particles, cosmetic particles, abrasive particles, and abrasion resistant particles, but in the following examples, silica nanoparticles will be used as light transmitting particles. [Example 1]

First, anhydrous silica nanoparticles 1 having a size of about 100nm were provided and dried. Next, a chemical adsorbent solution was prepared by weighting: a drug such as those shown by the following formulas (Formula 1 or 2) of 99 percent by weight, for a chemical adsorbent, having reactive functional groups such as epoxy groups or imino groups at an active site at one end and alkoxysilyl groups at the other end thereof; and an acetic acid of 1 percent by weight, for a silanol condensation catalyst, such as dibutyltin diacetylacetonate or organic acid, and solving the drug and the acetic acid into a silicone solvent such as a solvent mixture of hexamethyldisiloxane and dimethylformamide (50:50) to obtain a concentration of about 1 percent by weight (a preferable chemical adsorbent concentration is about 0.5 to 3%). [Formula 1]

O OCH₃

CH₂-CHCH₂O(CH₂)SSi -OCH₃

OCH₃

[Formula 2]

OCH₃

H₂N(CH₂)SSi -OCH₃ OCH₃

In the absorbent solution, anhydrous silica nanoparticles 1 were mixed and agitated, which was left in the air (relative humidity 45%) for about two hours for reaction. Since the anhydrous silica nanoparticle surfaces had a number of hydroxy groups 2 (Fig. 1A), -Si(OCH₃) groups in the chemical adsorbent and the hydroxy groups reacted with each other for dealcoholization (elimination of CH₃OH, in this case) under the silanol condensation catalyst or the acetic acid, so that a bonding shown by the following formula (Formula 3) or (Formula 4) was formed, resulting in a chemical absorbent monomolecular film 3 containing epoxy groups which were chemically bonded to the surface or a chemical absorbent film 4 containing amino groups having a film thickness of about 1 nanometer (Fig. 1B, 1C). When an absorbent containing amino groups was used, due to a precipitation generated by a tin-based catalyst, a better result was obtained using an organic acid such as an acetic acid. The amino groups contain imino groups, and pyrrole derivatives or imidazole derivatives also contain imino groups as well. With ketimine derivatives being used, amino groups were easily introduced by hydrolysis after a coating film was formed.

Next, when a chlorine solvent such as trichlene was used for agitation and cleaning, a silica nanoparticle 5 covered with a chemical absorbent monomolecular film which has reactive functional groups such as epoxy groups on the surface thereof, or a silica nanoparticle 6 covered with a chemical absorbent monomolecular film which has amino groups on the surface thereof could be produced. [Formula 3]

O O—

CH₂-CHCH₂O(CH₂)SSi — O—

[Formula 4]

O—

H₂N(CH₂J₃Si-O- O—

Since the coating film was extremely thin with a film thickness on the order of nanometer, the particle size was not damaged. Meanwhile, when the nanoparticles were not cleaned and left in the air, the reactivity remained unchanged, however, since the solvent was evaporated, the chemical adsorbent remaining on the particle surfaces reacted there with moisture in the air, resulting in nanoparticles having an extremely thin polymer film of the chemical adsorbent on the surface thereof.

This method that is characterized by dealcoholization reaction can be used to both organic and inorganic nanoparticles, which provides a wide potential for application. When Au nanoparticles are used, using a drug which has -SH or a triazine thiol group at one end thereof such as HkN(CH₂)_H-SH or H₂N(CH₂^-SH instead of Si(OCH₃)₃, gold nanoparticles on which a monomolecular film containing amino groups is formed, could be formed via the S. While, using a drug which has -SH or a methoxysilyl group at both ends thereof such as HS(CH₂)₃Si(OCH₃)₃, gold nanoparticles on which a monomolecular film containing methoxysilyl groups is formed could be formed via the S. Since the gold nanoparticles have the methoxysilyl groups on the surface thereof, a monolayer gold nanoparticle film could be formed directly on a substrate surface as in the case of forming a monomolecular film of this example. [Example 2] Similarly to Example 1, first, glass substrate 11 were provided and dried. Next, a chemical adsorbent solution was prepared by weighting: a drug such as those shown by the above formulas (Formula 1 or 2) of 99 percent by weight, for a chemical adsorbent, having reactive functional groups such as epoxy groups or imino groups at an active site at one end and alkoxysilyl groups at the other end thereof; and an acetic acid of 1 percent by weight, for a silanol condensation catalyst, such as dibutyltin diacetylacetonate or organic acid, and solving the drug and the acetic acid into a silicone solvent such as a hexamethyldisiloxane solvent to obtain a concentration of about 1 percent by weight (a preferable chemical adsorbent concentration is about 0.5 to 3%).

Next, glass substrate 11 was immersed into the absorbent solution, which was left in the air (relative humidity 45%) for about two hours for reaction. Since the glass substrate 11 had a number of hydroxy groups 12 on the surface thereof (Fig. 2A), the -Si(OCH₃) groups in the chemical adsorbent and the hydroxy groups reacted with each other for dealcoholization (elimination of CH₃OH, in this case) under the silanol condensation catalyst or the acetic acid, so that a bonding shown by the above formula (Formula 3) or (Formula 4) was formed, resulting in a chemical absorbent monomolecular film 13 containing epoxy groups (Fig. 2B) or a chemical absorbent film 14 containing amino groups (Fig. 2C) which were chemically bonded to the surface and had a film thickness of about 1 nanometer over the entire surface of the glass substrate 11.

Then, when a chlorine solvent such as trichlene was used for cleaning, a glass substrate 15 covered with a chemical absorbent monomolecular film which has reactive functional groups such as epoxy groups on the surface thereof, or a glass substrate 16 covered with a chemical absorbent monomolecular film which has amino groups on the surface thereof could be produced (Fig. 2B, 2C).

Since the coating film was extremely thin with a film thickness on the order of nanometer, the transparency of the glass substrate was not damaged.

Meanwhile, when the glass substrate was not cleaned with chlorine solvent and pulled out in the air, the reactivity remained unchanged, however, since the solvent was evaporated, the chemical adsorbent remained on the particle surfaces reacted there with moisture in the air, resulting in a glass substrate having an polymer film of the chemical adsorbent on the surface thereof, the polymer film being relatively somewhat thicker than the monomolecular film but still being extremely thin. [Example 3]

Next, the silica nanoparticles 6 covered with the chemical absorbent monomolecular film containing amino groups were dispersed in alcohol, which was applied to the surface of the glass substrate 15 covered with the chemical absorbent monomolecular film containing epoxy groups to be heated up to about 100 degrees C

(alternatively, a combination of the glass substrate surface covered with the chemical absorbent monomolecular film, containing amino groups and the silica nanoparticles covered with the chemical absorbent monomolecular film containing epoxy groups may be used).

Then, the amino groups of the silica nanoparticle surfaces which were in contact with the epoxy groups of the glass substrate surface were attached via a reaction as shown in the following formula (Formula 5), thereby the nanoparticles and the glass substrate were bound and fixed to each other via the two monomolecular films. In this reaction, an irradiation of supersonic rays to help the evaporation of alcohol enhanced the uniformity of a film thickness of each coating film. [Formula 5]

O

/ \

-(CH₂)CH-CH₂ + H₂NCH₂ —

— ► - (CH₂)CHCH₂ -NHCH₂ -

OH

Then, the substrate surface was cleaned again with alcohol to clean and remove the silica nanoparticle which was covered with chemical absorbent monomolecular film containing the excess and unreacted amino groups, resulting in the monolayer nanoparticle film 17 having a uniform thickness at a particle size was formed in which only a single layer of silica nanoparticles were laid out with being covered with a chemical absorbent monomolecular film containing amino groups that were covalently bound to the glass substrate surface 15 (Fig. 3A).

Meanwhile, when a coating film of silica nanoparticles that were covered with a chemical absorbent monomolecular film containing epoxy groups was formed on the glass substrate surface covered with a chemical absorbent monomolecular film containing amino groups, a monolayer nanoparticle film having a uniform thickness at a particle size was formed on which only a single layer of silica nanoparticles were laid out with being covered with a chemical absorbent monomolecular film containing amino groups that were covalently bound to the glass substrate surface.

At this point, a light transmittance of the glass substrate on which a monolayer nanoparticle film of silica nanoparticles was formed was measured. The measurement showed that the measured glass substrate had a better light transmittance by about 2% than a glass substrate that does not have a monolayer nanoparticle film of silica nanoparticles formed thereon. This means the coating film functioned as a antireflection coating.

The monolayer nanoparticle film of silica nanoparticles had an extremely uniform thickness of about 100 nm, and did not exhibit any interference color. [Example 4]

Subsequent to Example 3, in order to make a film thickness of a nanoparticle film increased, the silica nanoparticle 5 covered with chemical absorbent monomolecular films containing epoxy groups were dispersed in alcohol, which was applied to the surface of the glass substrate 15 covered with the chemical absorbent monomolecular film 17 that is a layer of silica nanoparticles covered with chemical absorbent monomolecular films containing covalently bound amino groups and has a uniform thickness at a particle size level, to be heated up to about 100 degrees C.

Then, the epoxy groups of the silica nanoparticle surfaces which were in contact with the amino groups of the glass substrate surface that had the monolayer nanoparticle film of silica nanoparticles covered with chemical absorbent monomolecular film containing amino groups were attached via a reaction as shown in the above formula (Formula 5), thereby the nanoparticles covered with the chemical absorbent monomolecular film containing amino groups on the glass substrate surface and the silica nanoparticle covered with the chemical absorbent monomolecular film containing epoxy groups were bound and fixed to each other via

, the two monomolecular films.

Then, the substrate surface was cleaned again with chloroform to clean and remove the silica nanoparticles which were covered with chemical absorbent monomolecular film containing the excess and unreacted amino groups, resulting in that a monolayer nanoparticle film 18 was formed, the monolayer nanoparticle film 18 being of a two-layer configuration of a uniform thickness at a particle size level, and having a second single layer of silica nanoparticles which was covalently bound to the glass substrate surface 15 via nanoparticles covered with the chemical absorbent monomolecular film containing amino groups (Fig. 3B).

And so on, when the silica nanoparticles which were covered with chemical absorbent monomolecular film containing amino groups and the silica nanoparticles which were covered with chemical absorbent monomolecular film containing epoxy groups were alternately laminated, which allowed a nanoparticle coating film of a multilayer configuration to be built up.

In the above Examples 1 and 2, the substance shown in the above the formula (Formula 1) or (Formula 2) was used as a chemical adsorbent containing reactive groups, but the following substances shown in the following list of (1) to (16) were able to be used as well as the above substances.

(1) (CH₂OCH)CH2θ(CH₂)7Si(OCH3)3

(2) (CH₂OCH)CH2θ(CH2)iiSi(OCH₃)3 (3) (CH₂CHOCH(CH2)2)CH(CH₂)2Si(OCH₃)3 (4) (CH₂CHOCH(CH2)2)CH(CH₂)4Si(OCH3)3 (5) (CH₂CHOCH(CH2)2)CH(CH2)6Si(OCH₃)3

(6) (CH₂OCH)CH₂O(CH₂)₇Si(OC₂Hs)₃

(7) (CH₂OCH)CH₂O(CH₂)I₁Si(OC₂Hs)₃ (8) (CH₂CHOCH(CH₂)₂)CH(CH₂)₂Si(OC₂H₅)₃ (9) (CH₂CHOCH(CH₂)₂)CH(CH₂)₄Si(OC₂H₅)₃

(10) (CH₂CHOCH(CH2)2)CH(CH2)6Si(OC₂H₅)₃

(11) H₂N(CH₂)₅Si(OCH₃)₃

(12) H₂N(CH₂)₇Si(OCH₃)₃

(13) H₂N(CH₂)₉Si(OCH₃)₃ (14) H₂N(CH₂)SSi(OC₂Hs)₃

(15) H₂N(CHs)₇Si(OC₂Hs)₃

(16) H₂N(CH₂J₉Si(OC₂Hs)₃ In the above list, the (CH₂OCH)- groups designate function groups shown in the following formula (Formula 6), and the (CH₂CHOCH(CH₂)₂)CH- shown in the following formula (Formula 7). [Formula 6]

O CH₂-CH -

[Formula 7]

In Examples 1 and 2, as the silanol condensation catalyst, carboxylic acid metal salt, carboxylic acid ester metal salt, carboxylic metal salt polymer, carboxylic acid metal salt chelate, titanate ester, and titanate ester chelate could be used.

More specifically, tin (I) acetic acid, dibutyltin dilaurate, dibutyltin dioctanoate, dibutyltin diacetate, dioctyltin dilaurate, dioctyltin dioctanoate, dioctyltin diacetate, tin

(I) octanate, lead naphthenate, cobalt naphthenate, iron 2- ethylhexanate, dioctyltin bisoctyl thioglycolate salt, dioctyltin maleate salt, dibutyltin maleate polymer, dimethyltin mercaptopropionate polymer, dibutyltin bis(acetyl acetate), dioctyltin bis acetyl laurate, tetrabutyltitanate, tetranonyltitanate, and bis acetyl acetonyl di-propyl titanate were able to be used.

Also, as a solvent for a film forming solution, an anhydrous organochlorine solvent, a hydrocarbonic solvent, a fluorocarbonic solvent, silicone-based solvent, of a mixture of these could be used. When a solvent was evaporated to increase a concentration of particles instead of cleaning, a preferable boiling point of a solvent was 50 to 250 degrees C. Furthermore, when an absorbent was based on alkoxysilane and a solvent was evaporated to form an organic coating film, an alcoholic solvent such as methanol, ethanol, and propanol, and a mixture of these could be used.

Specific examples which can be used to include chlorosilane-based non-aqueous petroleum naphtha, solvent naphtha, petroleum ether, petroleum benzin, isoparaffin, normalparaffin, decalin, industrial petrol, nonane, decane, kerosene, dimethyl silicone, phenylsilicone, alkyl denaturated silicone, polyether silicone, and dimethyl formamide.

A carbon fluoride based solvent may be a fluorine base solvent, Fluorinert

(3M Co. Ltd.), Afrude (manufactured by Asahi Glass Co. Ltd.), and the like. The above solvent may be used alone or as a combination of two or more solvents, which can be mixed well. Furthermore, an organochlorine solvent such as chloroform may be added to the solvent.

To the contrary, when a ketimine compound, organic acid, aldimine compound, enamine compound, oxazolidine compound, or an aminoalkyl alkoxysilane compound was used instead of the above silanol condensation catalyst, with the concentration being the same, the processing time could be reduced to half to two thirds.

When a mixture of the silanol condensation catalyst and one selected from the group of a ketimine compound, an organic acid, an aldimine compound, an enamine compound, an oxazolidine compound, an aminoalkyl alkoxysilane compound is used (at a ratio of 1:9 to 9:1 , but usually a ratio of about 1:1 is preferable), the processing time can be reduced to about one fifth (to about 30 minutes), and the film forming time can be reduced to about one fifth.

For example, when the above reaction was performed in the same condition except an H3 which is a ketimine compound manufactured by Japan Epoxy Resin Co. Ltd. was used instead of the dibutyltin oxide which is a silanol catalyst, similar results were obtained except the reaction time was reduced to about one hour.

Furthermore, when the above reaction was performed in the same condition except a mixture of the H3 which is a ketimine compound manufactured by Japan Epoxy Resin Co. Ltd. and dibutyltin bis(acetyl acetonate) which is a silanol catalyst that was used instead of the silanol catalyst, similar results were obtained, however, the reaction time was reduced to about 30 minutes. Therefore, the above result showed that a ketimine compound, organic acid, aldimine compound, enamine compound, oxazolidine compound, and an aminoalkyl alkoxysilane compound were more active than the silanol condensation catalyst.

A mixture of the silanol condensation catalyst and one selected from the group of a ketimine compound, organic acid, aldimine compound, enamine compound, oxazolidine compound, and an aminoalkylalkoxysilane compound was found to be more active.

The ketimine compound may be, but not limited to these examples: 2,5,8-triaza-1 ,8-nonadiene, 3,11 -dimethyl-4,7, 10-triaza-3, 10-tridecadiene, 2,10-dimethyl-3,6,9-triaza-2,9-undecadiene,

2,4, 12, 14-tetramethyl-5,8, 11 -triaza-4, 11 -pentadecadiene,

2,4, 15, 17-tetramethyl-5,8, 11,14-tetraaza-4, 14-octadecadiene, and

2,4,20,22-tetramethyl-5, 12,19-triaza-4, 19-tri-a-cosadien.

The organic acid may be, but not limited to, for example formic acid, acetic acid, propionic acid, butyric acid, and malonic acid, which all provided similar effects.

In the above Example 1 to 4, silica nanoparticles and a glass substrate are used for explanation, but the present invention can be applied to any nanoparticles which contain active hydrogens, that is, hydrogens of hydroxy groups or hydrogens of amino groups or imino groups, on the surface thereof, and a substrate. Specifically, the "inorganic nanoparticles" may be enanoparticles, semiconductor nanoparticles, insulating nanoparticles, magnetic nanoparticles, fluorescent nanoparticles, light absorbing nanoparticles, light transmitting nanoparticles, and pigment nanoparticles; the "organic nanoparticle," may be organic fluorescent nanoparticles, organic light absorbing nanoparticles, organic light transmitting nanoparticles, organic pigment nanoparticles, drug nanoparticles; and the "organic-inorganic hybrid nanoparticles," may be a laminated structure such as drug for DDS(Drug Delively System) nanoparticles, cosmetic nanoparticles, organic-inorganic hybrid pigment nanoparticles; and the "substrate," may be a resin plate, metal plate, and a ceramic plate.

Claims

1. A monolayer nanoparticle film, characterized by one layer of a nanoparticle film formed on a substrate surface is covalently bound to a first organic film formed on the substrate surface via a second organic film formed on nanoparticle surfaces.

2. The monolayer nanoparticle film according to claim 1 , characterized by the first organic coating film formed on the substrate surface is different from the second organic film formed on the nanoparticle surfaces.

3. The monolayer nanoparticle film according to claim 1 , characterized by the covalent binding is an NC bonding which is formed by a reaction between epoxy groups and imino groups.

4. The monolayer nanoparticle film according to Claim 1 and 2, characterized by the first organic coating film formed on the substrate surface and the second organic film formed on the nanoparticle surfaces are monomolecular films.

5. A method for manufacturing a monolayer nanoparticle film, characterized by its comprises: a step for forming a first reactive organic film on a substrate surface by contacting the substrate surface with a chemical adsorbent solution, which is made by mixing at least a first alkoxysilane compound, a silanol condensation catalyst, and a non-aqueous organic solvent to cause the substrate surface to react with the alkoxysilane compound; a step for forming second reactive organic films on nanoparticle surfaces by dispersing the nanoparticles into a chemical adsorbent solution, which is made by mixing at least a second alkoxysilane compound, a silanol condensation catalyst, and a non-aqueous organic solvent to cause the nanoparticle surfaces to react with the alkoxysilane compound; a step for contacting the nanoparticles covered with the second reactive organic films with the substrate surface on which the first reactive organic film is formed to cause the second reactive organic film and the first reactive organic film to react with each other; and a step for cleaning and removing excess nanoparticles covered with the second reactive organic film.

6. The method for manufacturing a monolayer nanoparticle film according to claim 5, characterized by its comprises: a step for forming a first reactive organic film on a substrate surface by contacting the substrate surface with a chemical adsorbent solution which is made by mixing at least a first alkoxysilane compound, a silanol condensation catalyst, and a non-aqueous organic solvent to cause the substrate surface to react with the alkoxysilane compound; a step for forming second reactive organic films on nanoparticle surfaces by dispersing the nanoparticles into a chemical adsorbent solution, which is made by mixing at least a second alkoxysilane compound, a silanol condensation catalyst, and a non-aqueous organic solvent to cause the nanoparticle surfaces to react with the alkoxysilane compound; and a step for individually cleaning the substrate and the nanoparticle surfaces using an organic solvent to form a first reactive monomolecular film, which is covalently bound to the substrate and a second reactive monomolecular film, which is covalently bound to the nanoparticle surfaces.

7. The method for manufacturing a monolayer nanoparticle film according to claim 5, characterized by the first reactive organic film contains epoxy groups and the second reactive organic film contains imino groups, or the first reactive organic film contains imino groups and the second reactive organic film contains epoxy groups.

8. The method for manufacturing a monolayer nanoparticle film according to claim 6, characterized by the first reactive monomolecular film contains epoxy groups and the second reactive monomolecular film contains imino groups, or the first reactive monomolecular film contains imino groups and the second reactive monomolecular film contains epoxy groups.

9. A multilayer nanoparticle film, characterized in that it is accumulated in layers on a substrate surface, and nanoparticles having organic coating films on the surfaces thereof are covalently bound to each other via the organic coating films across the layers.

10. The multilayer nanoparticle film according to claim 9, characterized by two kinds of organic coating films formed on the nanoparticle surfaces, and nanoparticles on which first organic films are formed and nanoparticles on which second organic

5 films are formed are alternately laminated.

11. The multilayer nanoparticle film according to claim 10, characterized by the first organic films and the second organic films react with each other to form covalent bonds.

10

12. The multilayer nanoparticle film according to claim 9, characterized by the covalent bonds are NC bonds formed by a reaction between epoxy groups and imino groups.

15 13. A method for manufacturing a multilayer nanoparticle film, characterized by its comprises: a step for forming a first reactive organic film on a substrate surface by contacting the substrate surface with a chemical adsorbent solution which is made by mixing at least a first alkoxysilane compound, a silanol condensation catalyst, and a non-aqueous organic solvent to cause the substrate surface to react with the

20 alkoxysilane compound; a step for forming a second reactive organic films on first nanoparticle surfaces by dispersing first nanoparticles into a chemical adsorbent i solution which is made by mixing at least a second alkoxysilane compound, a silanol condensation catalyst, and a non-aqueous organic solvent to cause the first nanoparticle surfaces to react with the alkoxysilane compound; a step for contacting

25 the substrate surface having the first reactive organic film formed thereon with the first nanoparticles which are covered with the second reactive organic films to cause the first reactive organic film and the second reactive organic films to react with each other; a step for forming a first monolayer nanoparticle film by cleaning and removing excess first nanoparticles covered with the second reactive organic films; a step for

30 forming third reactive organic films on second nanoparticle surfaces by dispersing the second nanoparticles into a chemical adsorbent solution which is made by mixing at least a third alkoxysilane compound, a silanol condensation catalyst, and a non-aqueous organic solvent to cause the second nanoparticle surfaces to react with the alkoxysilane compound; a step for contacting the substrate surface having the first monolayer nanoparticle film thereon which is covered with the second reactive organic film with the second nanoparticles which are covered with the third reactive organic films to cause the second reactive organic film and the third reactive organic films to react with each other; and a step for forming a second monolayer nanoparticle film by cleaning and removing excess second nanoparticle covered with the third reactive organic films.

14. The , method for manufacturing a multilayer nanoparticle film according to claim 13, characterized by the first reactive organic film is identical to the third reactive organic film.

15. The method for manufacturing a multilayer nanoparticle film according to claim 13, characterized in that after the step for forming the second monolayer nanoparticle films, the step for forming a first monolayer nanoparticle film and the step for forming second monolayer nanoparticle films are similarly repeated.

16. The method for manufacturing a multilayer nanoparticle film according to claim 13, characterized by its further comprises, after the steps for forming first to third reactive organic films, steps for forming first to third reactive monomolecular films which are covalentty bound to the substrate or the nanoparticle surfaces respectively by cleaning the substrate and the nanoparticle surfaces with an organic solvent.

17. The method for manufacturing a multilayer nanoparticle film according to claim 13, characterized by the first and third reactive organic films contain epoxy groups and the second reactive organic film contains imino groups, or the first and third reactive organic films contain imino groups and the second reactive organic film contains epoxy groups.

18. The monolayer nanoparticle film and the method for manufacturing a multilayer nanoparticle film according to claim 5 and 13, characterized by a ketimine compound, organic acid, aldimine compound, enamine compound, oxazolidine compound, or an aminoalkyl alkoxysilane compound is used instead of the silanol condensation catalyst.

19. The monolayer nanoparticle film and the method for manufacturing a multilayer nanoparticle film according to claim 5 and 13, characterized by at least one selected from the group consisting of a ketimine compound, organic acid, aldimine compound, enamine compound, oxazolidine compound, and an aminoalkyl alkoxysilane compound is mixed into the silanol condensation catalyst as a promoter.