KR20170105929A - Method of preparing nanocomposite film using amphiphilic layer-by-layer assembly and nanocomposite film prepared thereby - Google Patents

Abstract

The present invention relates to a method of preparing a nanocomposite film using amphiphilic layer-by-layer self-assembly in which an electrolyte polymer having various functional groups dispersed in a polar solvent and metal or transition metal oxide nanoparticles dispersed in a non-polar solvent are alternately laminated directly without any ligand replacement process; and to a nanocomposite film prepared by the method. According to the present invention, it is possible to produce a nanocomposite film in which nanoparticles are laminated at a high density and the particles are uniformly distributed without causing aggregation of the particles in a thin film.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a nanocomposite film produced by an amphiphilic layer-by-layer self-assembling method and a nanocomposite film produced from the nanocomposite film using the amphiphilic layer-

The present invention relates to a nanocomposite using an amphiphilic layer-like self-assembling method in which an electrolyte polymer having various functional groups dispersed in a polar solvent and metal or transition metal oxide nanoparticles dispersed in a non-polar solvent are alternately laminated directly without a ligand substitution process A nanocomposite film produced by the method, and a nanocomposite film produced therefrom.

Nanocomposite films composed of organic polymers and inorganic nanoparticles showed various possibilities to be applied in various fields such as blending, sol-gel, Langmuir-blag, catalyst, electric and electrochemical (G. Decher, Science , 277, 1232 (1997); AC Balazs et al., Science, 314, 1107 (2006); P. Podsiadlo et al., Science, 318, 80 (2007); Q. Ji et al., Angew. Chem. ACS Nano, 4, 3889 (2010); JJ Richardson et al., Science, 282, 1111 (1998); SW Lee et al. JY Ouyang et al., Nat. Mater., 3 (1986), pp. , AK Boal et al., Nature (2007), Nature, 918922 (2004); LC Hu et al., J. Am. Chem. Soc., 134,1107211075 , 404, 746748 (2000)).

Among them, the layer-by-layer assembly method (hereinafter referred to as LbL method) can form a solid multi-layer thin film based on the interaction of functional groups at the interface between adjacent layers, (G. Decher, Science, 277, 1232 (1997); P. Podsiadlo et al., Science, 318, 80 (2007); Q. Ji et al., Angew. Chem SW Lee et al., ACS Nano, 4, 3889 (2010), RK Iler, J. et al., Science, 282, 1111 (1998); Colloid & Inter. Sci., 21, 569 (1996)).

 The properties, performance, and applications of the polymer / inorganic nanoparticle films produced by the LbL method are based on the functionality (e.g., magnetic, catalytic or optical properties) and qualitative properties of the stacked inorganic nanoparticles (e.g., Size distribution, shape, or crystallinity), amount, and the functional groups of the polymer (C. Wang et al., Langmuir, 18, 3370 (2002); L. Zhai et al., Nano Lett ACS Nano, 5, 5417 (2011)), 4, 1349 (2004); B. Lee et al., Angew. Chem. .

The classical LbL method has been thoroughly divided into aqueous-based systems and organic solvent-based systems. First, in the case of an aqueous solution system using an electrostatic attractive force, there is a disadvantage in that the quality of nanoparticles dispersed in an aqueous solution synthesized in an aqueous solution is poor, and the amount of the particles is also small. To obtain nanoparticles with high quality properties, they must be synthesized in organic solvents rather than in aqueous media. In order to successfully laminate the synthesized nanoparticles through the LbL method, an organic solvent-based system using a polymer dispersed in an organic solvent has been reported (B. Lee et al., Angew. N. Krasteva et al., Nano (2007), Langmuir, 23, 10102 (2007); N. Krasteva et al. Lett., 2, 551 (2002)).

In addition, a study to fabricate polymer and inorganic nanoparticle multilayer thin film nanocomposite by LbL method based on nucleophilic substitution reaction, ligand exchange reaction, and ligand addition reaction with NH ₂ amine functional group and dispersed in organic solvent Y. Kim et al., Adv. Mater., 22, 5140-5144 (2010)], ; M. Yoon et al., ACS Nano, 5, 5417-5426 (2011), Y. Ko et al., ACS Nano, 7, 143-153 (2013)). However, the polymer used in the above-mentioned paper has a limit to use a specific polymer having an NH ₂ amine functional group and dispersed in an organic solvent.

In order to overcome this problem, a recently reported paper has proposed a LbL method which overcomes the polarity difference between water and organic solvent by using a polymer having SO 3 ^- sulfonic acid functional group dispersed in water and deviating from a polymer having NH ₂ amine functional group (M. Park, Y. Kim, Y. Ko et al., J. Am. Chem. Soc., 136, 17213-17223 (2014)). However, this is also limited to polymers having a sulfonic acid functional group having a negative charge, so that there is a limitation that various polymers having various functional groups can not be utilized.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems, and an object of the present invention is to provide a method for producing a polymer electrolyte membrane, which comprises a polymer electrolyte having various functional groups dispersed in a polar solvent and inorganic nanoparticles dispersed in a nonpolar solvent, And to provide a nanocomposite film using the laminated amphiphilic layered self-assembly method and a nanocomposite film produced therefrom.

It is another object of the present invention to provide a nonvolatile, resistive-transformable memory device comprising the nanocomposite film.

In order to solve the above problems, the present invention provides a method of producing a nanocomposite film comprising the steps of:

(a) adsorbing a polymer having a hydrophilic functional group dispersed in a polar solvent on a substrate;

(b) supporting the polymer-adsorbed substrate on a non-polar solvent in which inorganic nanoparticles are dispersed to induce self-assembly through interaction between the functional groups of the polymer and the inorganic nanoparticles, and adsorbing the inorganic nanoparticles; And

(c) Repeating the above steps (a) - (b) or (a) - (b) - (a) n times (n is an integer of 1 to 1000) to obtain a self- assembled polymer / nanoparticle nanocomposite film Lt; / RTI >

According to one embodiment of the present invention, the hydrophilic functional group may be at least one selected from the group consisting of a carboxyl functional group, an amine functional group, an ether functional group, a hydroxyl functional group, and a tertiary ammonium functional group.

According to an embodiment of the present invention, the polymer having hydrophilic functional groups may be at least one selected from the group consisting of PAA, PAH, PEO, PVA and PDDA.

According to an embodiment of the present invention, the polymer having the hydrophilic functional group may be a bioprotein having both a carboxyl functional group and an amine functional group.

At this time, the bioprotein may be a biogenic enzyme.

According to an embodiment of the present invention, the inorganic material may be a metal or a metal oxide.

At this time, the metal may be a transition metal.

The metal may be at least one selected from the group consisting of silver platinum iron manganese titanium.

The present invention also provides a nanocomposite film produced according to the above manufacturing method and a nonvolatile resistance-conversion memory device including the nanocomposite film.

According to the present invention, functional inorganic nanoparticles are directly laminated by an amphiphilic layer-like self-assembly method using various polymers having carboxyl functional groups, amine functional groups, ether functional groups, hydroxyl functional groups and tertiary ammonium functional groups dispersed in an aqueous solution In particular, when a polymer having a carboxyl functional group dispersed in an aqueous solution is used, the adsorption amount of the inorganic nanoparticles stacked thereon can be controlled by controlling the acidity of the aqueous solution in which the polymer is dispersed.

In addition, according to the present invention, various functional inorganic nanoparticles such as metal nanoparticles such as platinum and silver and transition metal nanoparticles such as titanium oxide, manganese oxide, and iron oxide can be applied to the present system.

According to the present invention, it is possible to produce nanocomposite films in which nanoparticles are stacked at a high density and the particles are evenly distributed without causing gravity or aggregation of the particles in the thin film. Furthermore, a biopolymer such as hemoglobin, catalase, It is possible to produce a nanocomposite film having a high nanoparticle laminating amount.

Further, the non-volatile resistance-reversible memory device having high performance and stability can be provided by applying the nanocomposite film produced according to the present invention.

1 is a schematic view showing a process for producing a nanocomposite film according to the present invention.
2 is a view showing the principle of the amphiphilic layer-by-layer self-assembly method used in the present invention and a process for producing the nanocomposite film according to the present invention.
3 is a SEM image of inorganic nanoparticles used in the present invention.
4 is a view showing FT-IR spectral results of the multilayer thin film according to Example 1. Fig.
5 is a diagram showing UV-vis spectral results of multilayer films according to Examples 2 to 6. FIG.
6 is a diagram showing UV-vis spectral results of the multilayered films according to Examples 7, 9, 11, and 13.
7 is a diagram showing UV-vis spectral results of the multilayered films according to Examples 8, 10, 12, and 14. Fig.
8 is a diagram showing UV-vis spectral results of the multilayered films according to Examples 15 and 16. FIG.
FIG. 9 is a diagram showing qualitative and quantitative analysis results of the adsorption amount of OA-TiO2 nanoparticles adsorbed on the PAA layer according to the acidity using a UV-vis spectrum and a quartz crystal microbalance. FIG.
10 is a graph showing the total thickness of the (PAA / TiO ₂ ) n nanocomposite film with acidity measured from a cross-sectional SEM image.

Hereinafter, the present invention will be described in more detail.

In the present invention, the polymer electrolyte material dispersed in water, the functional metal, and the transition metal oxide nanoparticles dispersed in the organic solvent are laminated at a high density without a separate ligand exchange process, and further, the nanocomposite It was confirmed that the film can be produced.

That is, in the present invention, it is confirmed that the polymer layer and the nanoparticle layer are laminated through the amphiphilic LbL method and repeatedly performed to produce a nanocomposite film, which can be used for an electronic device such as a nonvolatile resistance-change memory device.

The present invention further develops the LbL method in which an electrolyte polymer having a sulfonic acid functional group dispersed in water and an inorganic metal oxide nanoparticle dispersed in an organic solvent are directly laminated to form a carboxyl functional group, It has been confirmed that various polymers having an ether functional group, a hydroxyl functional group, and a tertiary ammonium functional group can be laminated with inorganic metal or metal oxide nanoparticles.

In particular, when the polymer / inorganic nanoparticle nanocomposite film is produced by using the polymer having a carboxyl functional group that is sensitive to the acidity of the aqueous solution, the acidicity of the polymer / inorganic nanoparticle nanocomposite film is controlled by adjusting the acidity of the inorganic nanoparticle The amount of adsorbed water can be controlled.

Specifically, the use of pH, which is an index indicating the acidity of an aqueous solution, indicates that as the pH increases and the acidity of the aqueous solution becomes weaker, the carboxyl functional group becomes stronger with a negative charge, and accordingly, the polymer having a carboxyl functional group exhibits an electrostatic repulsive force The amount of adsorbed inorganic nanoparticles to be adsorbed on the polymer continuously decreases due to the decrease in adsorption amount due to the morphological change of the polymer. As can be seen from the results of the following examples, It was confirmed that the adsorption amount of inorganic nanoparticles can be controlled by controlling the acidity of the aqueous solution.

Accordingly, the present invention provides a process for preparing a nanocomposite film comprising the steps of:

(a) adsorbing a polymer having a hydrophilic functional group dispersed in a polar solvent on a substrate;

(b) supporting the polymer-adsorbed substrate on a non-polar solvent in which inorganic nanoparticles are dispersed to induce self-assembly through interaction between the functional groups of the polymer and the inorganic nanoparticles, and adsorbing the inorganic nanoparticles; And

(c) Repeating the above steps (a) - (b) or (a) - (b) - (a) n times (n is an integer of 1 to 1000) to obtain a self- assembled polymer / nanoparticle nanocomposite film Lt; / RTI >

In the above, n may be 1 to 1000 times, preferably 1 to 500 times.

The hydrophilic functional group of the polymer used in the present invention may be at least one selected from the group consisting of a carboxyl functional group, an amine functional group, an ether functional group, a hydroxyl functional group, and a tertiary ammonium functional group.

The hydrophilic functional group-containing polymer may be a polyacrylic acid (PAA) represented by the following general formula (1).

[Chemical Formula 1]

In Formula 1, n is an integer of 2 to 5500.

The hydrophilic functional group-containing polymer may be a poly (allylamine hydrochloride) PAH having an amine functional group represented by the following general formula (2), a poly (ethylene oxide) (ethylene oxide) PEO), polyvinyl alcohol PVA having a hydroxyl functional group represented by the following formula (4), poly (diallyl dimethyl ammonium chloride) having a tertiary ammonium functional group represented by the following formula (5) Poly (diallyldimethylammonium chloride) PDDA).

(2)

In Formula 2, n is an integer of 2 to 5,000.

(3)

In Formula 3, n is an integer of 2 to 5,000.

[Chemical Formula 4]

In Formula 4, n is an integer of 2 to 5,000.

[Chemical Formula 5]

In Formula 5, n is an integer of 2 to 5,000.

In addition, the inorganic material may be a metal or a transition metal oxide, and the metal may be at least one selected from the group consisting of silver platinum iron manganese titanium.

The hydrophilic functional group-containing polymer may be a bioprotein having both a carboxyl functional group and an amine functional group, and may be a biosynthetic enzyme such as Catalase, Hemoglobin, and Ferritin. The nanoparticles contained in the nanocomposite film produced according to the present invention exhibit a high packing density of 50-65%. According to the present invention, nanoparticles are stacked at a high density, It is possible to provide a nanocomposite film in which the particles are evenly distributed.

Further, as the pH of the polymer having carboxyl functional groups sensitive to the acidity of the aqueous solution becomes higher, the acid functionalities of the aqueous solution become weaker, the carboxyl functional groups become more strongly negative, and the adsorption amount decreases due to the electrostatic repulsion and structural change. The adsorption amount of inorganic nanoparticles to be continuously adsorbed is also reduced. According to the present invention, the amount of adsorbed inorganic nanoparticles can be controlled by controlling the acidity of the aqueous solution in which the polymer is dispersed.

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments and the like. It will be apparent to those skilled in the art, however, that these examples are provided for further illustrating the present invention and that the scope of the present invention is not limited thereto.

Manufacturing example  1: hydrophobic OA Synthesis of Pt Nanoparticles

Chao Wang et al. (A General Approach to Shape-Controlled Synthesis of Platinum Nanoparticles and Their Catalytic Reduction of Oxygen. Angew. Chem. Int. Ed., 47, 3588-3591, (2008) OA-Pt nanoparticles dispersed in toluene were prepared. The concentration of the nanoparticle solution was adjusted to 5 mg / mL (Fig. 3B)

Manufacturing example  2: hydrophobic OA - Ag  Synthesis of nanoparticles

OA-Ag nanoparticles dispersed in toluene were prepared by the method disclosed in Lin, X. Z. et al. (Direct Synthesis of Narrowly Dispersed Silver Nanoparticles Using a Single-Source Precursor. Langmuir 19, 10081-10085 (2003) The concentration of the nanoparticle solution was adjusted to 5 mg / mL (Fig. 3A).

Manufacturing example  3: Hydrophobic OA - Fe3O4  Synthesis of nanoparticles

OA-Fe3O4 nanoparticles dispersed in toluene were prepared by the method described in SH Sun et al. (Monodisperse MFe2O4 (M = Fe, Co, Mn) Nanoparticles, J. Am. Chem. Soc., 126, 273279 Respectively. The concentration of the nanoparticle solution was adjusted to 5 mg / mL (Fig. 3E).

Manufacturing example  4: hydrophobic OA - MnO  Synthesis of nanoparticles

MnO nanomaterials dispersed in toluene by the method disclosed in Na, HB et al., (1999), Development of a T1 Contrast Agent for Magnetic Resonance Imaging Using MnO Nanoparticles, Angew. The particles were prepared. The concentration of the nanoparticle solution was adjusted to 5 mg / mL (FIG. 3D)

Manufacturing example  5: hydrophobic OA - TiO2  Synthesis of nanoparticles

OA-TiO2 nanoparticles dispersed in toluene were prepared by the method described in Pan, D. et al. (Facile Synthesis and Characterization of Luminescent TiO2 Nanocrystals. Adv. Mater. 17, 1991-1995 (2005)). The concentration of the nanoparticle solution was adjusted to 5 mg / mL (Fig. 3C)

Example  One: ( PAA / TiO2 ) n Manufacturing of multilayer thin film

The OA-TiO2 nanoparticles synthesized in Preparation Example 5 were prepared in a toluene solution at a concentration of 5 mg / mL, and a 1 mg / mL PAA solution (Mw = 130,000, Aldrich) dispersed in water and 1 mg / mL (PAH, Mw = 70,000, Aldrich) was prepared as a solution of poly (arylamine hydrochloride) (PAA solution). To examine the tendency of the PAA solution, 3, 5, 7, and 9, respectively.

Quartz or silicon substrates were first cleaned with RCA solution (H2O / NH3 / H2O2 5: 1: 1: v / v / v) at 80 ° C to prepare multilayers using the LbL assembly method. The resulting negatively charged substrate was supported for 10 minutes in positively charged PAH (Mw = 70,000, Aldrich), washed twice with deionized water and dried. The PAH-coated substrate was immersed in a PAA solution having different pH for 10 minutes, then the hydrophobic nanoparticles were adsorbed for 10 minutes, washed with toluene and dried. The above procedure was repeated until the desired multi-layer water was obtained.

As shown in FIG. 1, OA-TiO ₂ nanoparticles of about 10 nm in diameter were prepared in an organic solvent according to Example 1 of the present invention, and a PAA high-affinity material having a COOH carboxyl functional group dispersed in water was used Polymer / inorganic nanoparticle multilayer thin film nanocomposite films were prepared by LBL method.

First, it was confirmed by FT-IR spectroscopy that the particles were laminated by the ligand exchange method due to the interaction between the COOH carboxyl functional group of the PAA polymer and the surface of the OA-TiO ₂ nanoparticles.

The FT-IR spectrum of PAA showed a prominent absorption peak attributable to the C = O stretching peak (1725 cm -1) oscillation of the COOH functional group. The oleic acid ligand, which is used as a stabilizer of nanoparticles and bound to the surface of the nanoparticles, has long CH2 alkyl chains. The CH2 stretching peaks (2929 cm-1 and 2855 cm-1) due to this long alkyl chain indicate that the OA ligand is bound to the surface of the TiO2 nanoparticles (Fig. 4A).

Therefore, as the PAA layer as a function of the deposition time of the PAA polymer in the multilayer thin film of PAA / OA-TiO2 nanoparticles is further absorbed onto the film coated with the OA-TiO2 nanoparticles, the absorption peak intensity of the CH2 stretching gradually decreases and the COOH The peak intensity due to the functional group was increased (Fig. 3A). These results indicate that the loosely bound OA ligand on the surface of TiO2 nanoparticles is replaced by the COOH functional group of PAA. As a result, PAA and OA-TiO ₂ The alternation of the nanoparticles shows that the peak intensities of the COOH and CH ₂ stretching frequencies are opposite (Fig. 4B).

Example  2: ( PAA / OA -Pt) n Multi-layer Thin Film Fabrication

(PAA / OA-Pt) n multilayer thin film was prepared (FIG. 5B), except that OA-Pt nanoparticle solution stabilized with oleic acid synthesized in Preparation Example 1 was used.

Example  3: ( PAA / OA - Ag ) n Manufacturing of multilayer thin film

(PSS / OA-Ag) n multilayer thin film was prepared in the same manner as in Example 1 except that the OA-Ag nanoparticle solution stabilized with oleic acid synthesized in Production Example 2 was used (FIG. 5A).

Example  4: ( PAA / OA - Fe3O4 ) n Manufacturing of multilayer thin film

(PAA / OA-Fe3O4) n multilayered thin film was prepared in the same manner as in Example 1 except that the OA-Fe3O4 nanoparticle solution stabilized with oleic acid synthesized in Production Example 3 was used (Fig. 5C)

Example  5: ( PAA / OA - MnO ) n Manufacturing of multilayer thin film

(PAA / OA-MnO) n multilayer thin film was prepared in the same manner as in Example 1 except that the OA-MnO nanoparticle solution stabilized with oleic acid synthesized in Production Example 4 was used (Fig. 5d)

Example  6: ( PAA / OA - TiO2 ) n Manufacturing of multilayer thin film

(PAA / OA-TiO2) n multilayer thin film was prepared in the same manner as in Example 1 except that the OA-TiO2 nanoparticle solution stabilized with oleic acid synthesized in Production Example 5 was used (Fig. 5e)

Example  7: ( PDDA / OA - TiO2 ) n Manufacturing of multilayer thin film

The OA-TiO2 nanoparticles synthesized in Production Example 5 were prepared in a toluene solution at a concentration of 5 mg / mL, and a 1 mg / mL PDDA solution (Mw = 300,000, Aldrich) dispersed in water and 1 mg / mL (Mw = 70,000, Aldrich) was prepared (Fig. 6-d).

Quartz or silicon substrates were first cleaned with RCA solution (H2O / NH3 / H2O2 5: 1: 1: v / v / v) at 80 ° C to prepare multilayers using the LbL assembly method. The resulting negatively charged substrate was immersed in a positively charged PDDA solution for 10 minutes followed by adsorption of the hydrophobic nanoparticles for 10 minutes, washing with toluene and drying. The above procedure was repeated until the desired multi-layer water was obtained.

Example  8: ( PDDA / OA -Pt) n Multi-layer Thin Film Fabrication

(PDDA / OA-Pt) n multilayer thin film was prepared in the same manner as in Example 7 except that the OA-Pt nanoparticle solution stabilized with oleic acid synthesized in Production Example 1 was used (Fig. 7-d).

Example  9: ( PVA / OA - TiO2 ) n Manufacturing of multilayer thin film

The OA-TiO2 nanoparticles synthesized in Preparation Example 5 were prepared in a toluene solution at a concentration of 5 mg / mL, and a 1 mg / mL PVA solution (Mw = 70,000, Aldrich) dispersed in water and 1 mg / mL (Mw = 70,000, Aldrich) are prepared.

Quartz or silicon substrates were first cleaned with RCA solution (H2O / NH3 / H2O2 5: 1: 1: v / v / v) at 80 ° C to prepare multilayers using the LbL assembly method. The resulting negatively charged substrate was supported for 10 minutes in positively charged PAH (Mw = 70,000, Aldrich), washed twice with deionized water and dried. The substrate coated with PAH was immersed in PDDA solution for 10 minutes, then adsorbed the hydrophobic nanoparticles for 10 minutes, washed with toluene and dried. The above procedure was repeated until a desired multi-layer water was obtained (Figure 6a)

Example  10: ( PVA / OA -Pt) n Multi-layer Thin Film Fabrication

(PVA / OA-Pt) n multilayered thin film was prepared in the same manner as in Example 9 except that OA-Pt nanoparticle solution stabilized with oleic acid synthesized in Production Example 1 was used (Fig. 7a)

Example  11: ( PEO / OA - TiO2 ) n Manufacturing of multilayer thin film

The OA-TiO2 nanoparticles synthesized in Production Example 5 were prepared in toluene at a concentration of 5 mg / mL, and a 1 mg / mL PEO solution (Mw = 100,000, Aldrich) dispersed in water and 1 mg / mL (Mw = 70,000, Aldrich) was prepared.

Quartz or silicon substrates were first cleaned with RCA solution (H2O / NH3 / H2O2 5: 1: 1: v / v / v) at 80 ° C to prepare multilayers using the LbL assembly method. The resulting negatively charged substrate was supported for 10 minutes in positively charged PAH (Mw = 70,000, Aldrich), washed twice with deionized water and dried. The substrate coated with PAH was immersed in the PEO solution for 10 minutes, then the hydrophobic nanoparticles were adsorbed for 10 minutes, washed with toluene and dried. The above procedure was repeated until the desired multi-layer water was obtained (Fig. 6-b).

Example  12: ( PEO / OA -Pt) n Multi-layer Thin Film Fabrication

(PEO / OA-Pt) n multilayered thin film was prepared in the same manner as in Example 11 except that OA-Pt nanoparticle solution stabilized with oleic acid synthesized in Production Example 1 was used (Fig. 7B)

Example  13: ( PAH / OA - TiO2 ) n Manufacturing of multilayer thin film

The OA-TiO2 nanoparticles synthesized in Production Example 5 were prepared in a toluene solution at a concentration of 5 mg / mL, and a PAH solution (Mw = 70,000, Aldrich) having a concentration of 1 mg / mL dispersed in water was prepared.

Quartz or silicon substrates were first cleaned with RCA solution (H2O / NH3 / H2O2 5: 1: 1: v / v / v) at 80 ° C to prepare multilayers using the LbL assembly method. The resulting negatively charged substrate was supported for 10 minutes in positively charged PAH (Mw = 70,000, Aldrich), washed twice with deionized water and dried. The hydrophobic nanoparticles were adsorbed on the PAH coated substrate for 10 minutes, washed with toluene and dried. The process was repeated until the desired multi-layer water was obtained (FIG. 6C).

Example  14: ( PAH / OA -Pt) n Multi-layer Thin Film Fabrication

(PAH / OA-Pt) n multilayered thin film was prepared in the same manner as in Example 13 except that OA-Pt nanoparticle solution stabilized with oleic acid synthesized in Production Example 1 was used (Fig. 7C)

Example  15: (CAT / OA - TiO2 ) n Manufacturing of multilayer thin film

The OA-TiO2 nanoparticles synthesized in Production Example 5 were prepared in a toluene solution at a concentration of 5 mg / mL, and a CAT solution (40,000-60,000 units / mg protein (E1% / 405), Aldrich ) And a 1 mg / mL PAH solution (Mw = 70,000, Aldrich) dispersed in water are prepared. Two kinds of CAT solutions were prepared, pH 3 and 9.

Quartz or silicon substrates were first cleaned with RCA solution (H2O / NH3 / H2O2 5: 1: 1: v / v / v) at 80 ° C to prepare multilayers using the LbL assembly method. The resulting negatively charged substrate was supported for 10 minutes in positively charged PAH (Mw = 70,000, Aldrich), washed twice with deionized water and dried. The substrate coated with PAH was immersed in the CAT solution for 10 minutes, then the hydrophobic nanoparticles were adsorbed for 10 minutes, washed with toluene and dried. The above procedure was repeated until a desired multi-layer water was obtained (Figure 8a)

Example  16: (CAT / OA -Pt) n Multi-layer Thin Film Fabrication

(CAT / OA-Pt) n multilayer thin film was prepared in the same manner as in Example 15 except that the OA-Pt nanoparticle solution stabilized with oleic acid synthesized in Production Example 1 was used. (Fig. 8-b)

Experimental Example

UV- vis Spectrocopy

The UV-vis spectrum of the organic polymer / inorganic nanoparticle multilayer film on quartz glass was analyzed with a Perkin Elmer Lambda 35 UV-vis spectrometer.

Quartz crystal Micro weight equipment (Quartz Crystal Microgravimetry , QCM ) Measure

After each adsorption step, the mass of the material deposited on each layer was measured using a QCM device (QCM200, SRS).

The resonance frequency of the QCM electrode was about 5 MHz. The adsorbed mass m of the PAA polymer and inorganic nanoparticles was calculated from the change in QCM frequency, F, using the Sauer-Bray equation (Buttry, D. Advances in Electroanalytical Chemistry: Applications of the QCM to Electrochemistry. Marcel Dekker: New York, 1991).

Here, F0 (~5 MHz) is the fundamental resonance frequency of the crystal, A is the electrode area, q (~ 2.65 gcm ^-2 ) and q (~ 2.95x10 ^ 11 gcm ^-2 s ^{- 2} ) modulus) and the density of quartz. This equation can be simply expressed as:

Fourier Transform Infrared Spectroscopy (FTIR)

The vibrational spectra were measured by FTIR spectroscopy (iS50 FTIR Thermo Fisher) in transmission and attenuated total reflection (ATR) mode. Prior to FTIR measurements, the sample chamber was purged with N ₂ gas for 2 hours to remove water vapor and carbon dioxide. An ATR-FTIR spectrum of (PAA / TiO ₂ ) n film was obtained by scanning 102 times with an incident angle of 80 ° on an Au-coated silicon wafer substrate. The obtained raw data was plotted after baseline correction, and the spectrum was smoothed using spectrum analysis software (OMNIC, Nicolet).

Also, by comparing the ATR-FTIR adsorption peak area of the COOH functional group (at 1725 cm-1) of the PAA with the CH2 functional group (at 2929, 2855 cm-1) of the OA ligand as a function of PAA adsorption time The relative conversion rate was calculated.

Experimental Example  1: Measurement of adsorption amount of inorganic nanoparticles according to acidity of aqueous polymer solution

The adsorption amount of OA-TiO ₂ nanoparticles on the PAA layer prepared according to different acidity (ie, H + ion concentration) was quantitatively observed using UV-vis spectroscopy and qualitatively using a quartz crystal microbalance (QCM) (Fig. 9).

PAA and OA- TiO ₂ The amount of nanoparticles deposited was 2.06 μg in the case of pH 3 aqueous PAA solution. However, when the acidity of PAA aqueous solution was increased from pH 3 to pH 9, the amount of lamination decreased to 1.08 μg. The PAA pH 3 and OA-TiO ₂ when continuously laminated to the nanoparticles, regular and linear growth (PAA / OA- TiO ₂₎ n multi-layer thin film, as shown in Figure 4-b was observed. The density of the OA-TiO ₂ nanoparticles using about 3.78 gcm ^- considering that ^3, the number density of the OA-TiO ₂ nanoparticles adsorbed by the PAA polymer layer striking the acidity of pH3 (number density) of about 8.99 x 10 ^ 11 cm ^-2 , which corresponds to a filling density of 52% and is close to the maximum filling density (64%) for a randomly proximally filled particle layer.

The above results indicate that the adsorption amount of the inorganic nanoparticles dispersed in the nonpolar solvent is significantly influenced by the adsorption state of the previously adsorbed PAA having the fixed charge density. More specifically, as the acidity of the polymer aqueous solution decreases, that is, as the pH increases, the charge density of the COOH functional group in the polymer electrolyte chain increases and the electrostatic repulsion force resulting therefrom increases, thereby decreasing the adsorption amount of the PAA electrolyte polymer The adsorption amount of the inorganic nanoparticles continuously deposited is decreased. Also, the charge density of the polymer electrolyte material changes from a flexible loop, tail, and tangential structure to a rigid, linear structure. This also reduces the amount of inorganic nanoparticles adsorbed thereon. For example, if you put a bead in a soft place with a futon, the bead will rise well on the comforter, but if you put a bead on the hard marble floor, it will be easy to be scattered. The loop, tail, and entanglement structures of the polymer act like a fluffy duvet on the substrate when viewed from the nanometer scale, allowing the nanoparticles to be more firmly adsorbed.

Claims (10)

A process for preparing a nanocomposite film comprising the steps of:
(a) adsorbing a polymer having a hydrophilic functional group dispersed in a polar solvent on a substrate;
(b) supporting the polymer-adsorbed substrate on a non-polar solvent in which inorganic nanoparticles are dispersed to induce self-assembly through interaction between the functional groups of the polymer and the inorganic nanoparticles, and adsorbing the inorganic nanoparticles; And
(c) Repeating the above steps (a) - (b) or (a) - (b) - (a) n times (n is an integer of 1 to 1000) to obtain a self- assembled polymer / nanoparticle nanocomposite film Lt; / RTI > The method according to claim 1,
Wherein the hydrophilic functional group is at least one selected from the group consisting of a carboxyl functional group, an amine functional group, an ether functional group, a hydroxyl functional group, and a tertiary ammonium functional group. The method according to claim 1,
Wherein the hydrophilic functional group-containing polymer is at least one selected from the group consisting of PAA, PAH, PEO, PVA, and PDDA. The method according to claim 1,
Wherein the polymer having the hydrophilic functional group is a bioprotein having both a carboxyl functional group and an amine functional group. 5. The method of claim 4,
Wherein the bioprotein is a biogenic enzyme. The method according to claim 1,
Wherein the inorganic material is a metal or a metal oxide. The method according to claim 6,
Wherein the metal is a transition metal. The method according to claim 6,
Wherein the metal is at least one selected from the group consisting of silver platinum iron manganese titanium. A nanocomposite film produced according to any one of claims 1 to 8. A non-volatile, resistance-transformable memory device comprising the nanocomposite film of claim 9.

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