KR20100112049A - Method for producing metal nano structures using ionic liquid - Google Patents

Abstract

PURPOSE: A method for manufacturing metal nanostructure is provided to uniformly produce metal structure of various forms using ionic liquid. CONSTITUTION: A method for manufacturing metal nanostructure comprises a step of mixing ionic liquid, metal salt and reduction solvent and reacting to form metal nanostructure of various shapes. A method for determining the form of metal nanostructure comprises: a step of forming one-dimensional structure such as nanowire using ionic liquid with anion of sulfide having alkylsulfate(RSO_4^-) or akylsulfonate(RSO_3^-); a step of forming three dimensional structure using an ionic liquid with anion of halides; and a step of forming octahedron structure in case of bromine anion(Br^-).

Description

Method for producing metal nano structures using ionic liquid

The present invention relates to a method for producing a nano-sized metal nanostructure, and more specifically, by using an ionic liquid in the polyol reduction reaction using a metal salt as a precursor, various forms such as cubic or octahedral particles and nanowires The present invention relates to a method for uniformly preparing a metal nanostructure.

Recently, many researches have been conducted on the synthesis of metal nanoparticles for various fields such as flat panel displays, touch panels, and solar cells. Since these metal nanoparticles can be applied to various fields such as transparent electrodes or conductive inks, there is a need for an invention of mass production of these metal nanoparticles. At this time, since the shape of the metal nanoparticles is an important factor influencing the characteristics of the electrical conductivity and the like, an invention of a technology capable of freely controlling the shape of the metal nanoparticles is required.

Recently, when a metal salt precursor is prepared using a polyol reducing agent such as ethylene glycol, and a compound such as polyvinylpyrrolidone is used to prepare a metal nanostructure, a technique for producing a metal structure in the form of a wire has been reported. (Chem. Mater. 14, 4736-4745). The technique is called a polyol reduction method, and this method has an advantage that it is relatively easy to prepare a solution-shaped metal nanostructure. However, the metal nanostructures prepared by the above-described methods are often wire-shaped, but in many cases, the structure having the shape of other nanoparticles as well as the wire shape is mixed, and the shape of the nano-structure is reproducible depending on the reaction conditions. There is a disadvantage of being difficult.

Therefore, in the manufacture of metal nanostructures, there is a need for the invention of a technology in which the final product can uniformly and freely control the shape of the metal nanostructures such as wire shape, cubic shape, or octahedral shape.

It is an object of the present invention to provide a method of freely selecting and uniformly preparing metal nanostructures of various shapes using an ionic liquid. That is, in the polyol reduction reaction using a metal salt as a precursor using the present invention, metal nanostructures having various shapes such as wire shape, cubic shape, and octahedral shape can be uniformly and freely produced.

The problem to be achieved by the present invention is not limited to the above-mentioned problem, another task that is not mentioned will be clearly understood by those skilled in the art from the following description.

In order to achieve the object of the present invention as described above, the present invention is a method for producing a metal nanostructure of various shapes by mixing and reacting an ionic liquid, a metal salt and a reducing solvent.

In addition, the present invention is characterized in that the shape structure of the metal nanostructure is determined by the chemical bonding structure of the cation and anion constituting the ionic liquid by mixing and reacting the ionic liquid, the metal salt and the reducing solvent.

In addition, the present invention is a method for producing a metal nanostructure by mixing and reacting an ionic liquid, a metal salt and a reducing solvent, wherein the metal nanostructure by the ionic liquid various structures including a one-dimensional, two-dimensional or three-dimensional shape Characterized in that to have.

In the present invention, a method of changing the shape of the metal nanoparticles by using an ionic liquid in the polyol reduction reaction of the precursor of the metal salt and changing the anion component of the ionic liquid.

The present invention is to prepare a metal particle through a polyol reduction reaction by mixing and reacting an ionic liquid, a metal salt and a reducing solvent, to prepare metal nanoparticles of different shapes by different kinds of anions of the ionic liquid. It is done.

The metal salt is AgNO ₃ , Ag (CH ₃ COO) ₂ , AgClO ₄ , Au (ClO ₄ ) ₃ , PdCl ₂ , NaPdCl ₄ , PtCl _{2 ,} SnCl ₄ , HAuCl ₄ , FeCl ₂ , FeCl ₃ , Fe (CH ₃ COO ) ₂ , CoCl ₂ , K ₄ Fe (CN) ₆ , K ₄ Co (CN) ₆ , K ₄ Mn (CN) _6, K ₂ CO _3, including most metal cations and organic or inorganic anions, Most metal salts can be used without being limited to metal elements. The metal salt is converted into the corresponding metal nanoparticles such as silver, gold, palladium, tin, iron, and cobalt through a reduction reaction.

The reducing solvent is a polar solvent capable of dissolving a metal salt, and refers to a solvent such as diol, polyol, or glycol having at least two hydroxyl groups in a molecule. Specific examples thereof include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, glycerin, glycerol, polyethylene glycol, polypropylene glycol, and the like. The polyol reducing solvent serves to induce a reduction reaction of the metal salt to generate metal elements.

The ionic liquid is a compound composed of an organic cation and an organic or inorganic anion, and is characterized in that it is an imidazolium ionic liquid of Formula 1a and / or a pyridinium ionic liquid of Formula 1b.

R ₁ in Chemical Formula 1a And R ₂ are the same or different and represent hydrogen or a hydrocarbon group of 1 to 16 carbon atoms, and may include a heteroatom. And X ⁻ represents an anion of an ionic liquid.

R ₃ in Formula 1b And R _{4, which} is the same or different, represents hydrogen or a hydrocarbon group having 1 to 16 carbon atoms, and may include a heteroatom. And X ⁻ represents an anion of an ionic liquid.

Specific examples of the cation of the imidazolium ionic liquid represented by the formula (1a) include 1,3-dimethylimidazolium, 1,3-diethylimidazolium, 1-ethyl-3-methylimidazolium , 1-butyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium, 1-octyl-3-methylimidazolium, 1-decyl-3-methylimidazolium, 1-dodecyl- 3-methylimidazolium, 1-tetradecyl-3-methylimidazolium, and the like. Examples of the pyridinium-based ionic liquid cation represented by Formula 1b include 1-methylpyridinium, 1-ethylpyridinium, 1-butylpyridinium, 1-ethyl-3-methylpyridinium, 1-butyl-3-methylpyridinium, 1-hexyl-3-methylpyridinium, 1-butyl-3,4-dimethylpyridinium .

In addition, the ionic liquid cation of the present invention includes not only the ionic liquid of the monomolecular form represented by the formula (1a) or the formula (1b) but also the ionic liquid of the polymer form, for example, poly (1-vinyl-3-alkylimide). Jolium), poly (1-vinyl-pyridinium), poly (1-vinyl-alkylpyridinium), poly (1-allyl-3-alkylimidazolium), poly (1- (meth) acryloyloxy- 3-alkylimidazolium), and the like, and are not limited to any particular compound.

The monomolecular or ionic liquid in a polymer form becomes an organic or inorganic anion, for example, ^{Br -, Cl -, I -} , BF 4 -, PF 6 -, ClO 4 -, NO 3 -, AlCl 4 - ^{_{, Al 2 Cl 7 -, AsF}} 6 -, SbF 6 -, CH 3 COO -, CF 3 COO -, CH 3 SO 3 -, C 2 H 5 SO 3 -, CH 3 SO 4 -, C 2 H 5 SO _{^{4 -, CF 3 SO 3 -}} , (CF 3 SO 2) 2 N -, (CF 3 SO 2) 3 C -, (CF 3 CF 2 SO 2) 2 N -, C 4 F 9 SO 3 -, C ^{_{3 F 7 COO -, (CF}} 3 SO 2) (CF 3 CO) N - and the like, and is not limited to any particular compound.

The ionic liquid in the form of a single molecule or a polymer can be configured with various physical and chemical properties depending on the combination of cations and anions. Preferably, the ionic liquid has a high compatibility with metal salts and reducing solvents. The ionic liquid serves to help the metal element to grow one-dimensional, two-dimensional or three-dimensional by chemically interacting with the metal ion or the metal element when the metal salt is converted into the metal element by the polyol reduction reaction. Finally, metal particles having a uniform shape are produced.

In particular, the anion component of the ionic liquid determines the shape of the finally prepared metal nanoparticles, for example, an ionic having an anion of a sulfur compound such as alkyl sulfate (RSO ₄ ⁻ ) or alkyl sulfonate (RSO ₃ ⁻ ). using a liquid when in a primarily one-dimensional growth is made of the metal structure of the nanowire shape, halide (halide) based If with an anion using ionic liquids three-dimensional to the growth chlorine negative ions (Cl ^-), mainly when the form of a cube In the case of the bromine anion (Br ⁻ ), a metal structure having an octahedral particle shape is prepared. According to the anion component of the ionic liquid, metal nanoparticles having different shapes can be selectively produced. The final shape of the nanostructures is that the growth direction of the metal nanoparticles is changed by the interaction between the metal nanoparticles and the ionic liquid in the initial stage of the reaction, so the anion of the ionic liquid plays an important role in this step. . That is, at the beginning of the reaction, metal salts are first formed by the reducing solvent, and metal nanoparticles are formed first, and the metal nanoparticles interact with the anions (Cl-, Br-, CH3SO4-) of the ionic liquid to help growth in a certain direction. The metal nanostructures of various shapes can be manufactured.

As a representative example of the present invention, a specific method of manufacturing a metal nanostructure having a nanowire shape is as follows. First, the ionic liquid consisting of the metal salt, the reducing solvent and the sulfide anion is mixed at an appropriate ratio and stirred at room temperature for a certain time. When uniform mixing is achieved, the metal nanowires are manufactured by continuing the reaction by raising the reaction temperature of the mixture to 150-200 degrees Celsius. The metal nanowires thus prepared have almost no nanoparticle shape, and have a nanowire shape having an average diameter of 0.01 to 0.1 micron and an average length of 5 to 100 microns. In order to have the shape of the nanowire in the above process, it is necessary to properly control the mixing ratio of each component, which is 0.01 to 1 molar concentration of the metal salt and the ionic liquid (in the case of the polymer type ionic liquid) It is preferable to maintain the concentration in the range of 0.001 to 1 molar. If the concentration is less than the lower limit, the concentration is too low, the content of the metal wire produced is too low, or the content of the ionic liquid is too low, it is disadvantageous that the production of metal nanowire is not good. On the other hand, if the concentration of the metal salt is 1 mol or more, the content of the metal salt is so high that the resulting metal particles stick to each other or the particle size is disadvantageous, or if the content of the ionic liquid is 1 mol or more, the total solution Too high a viscosity of the metal nanowires synthesis is difficult and rather disadvantageous.

By using the same method as described above and using an ionic liquid having different anions, it is possible to uniformly and stably synthesize the cubic metal nanoparticles or the octahedral metal nanoparticles.

In the method for producing metal nanostructures of various shapes by mixing and reacting the ionic liquid, the metal salt, and the reducing solvent of the present invention, in order to more effectively control the shape and size of the metal nanostructures, the nitrogen compound of Formula 2a or It is possible to add the sulfur compound of 2b as an additive, wherein the content range of the compound is preferably 0.1 to 100 parts by weight based on 100 parts by weight of the metal salt. When the concentration of these compounds is 0.1 parts by weight or less, the shape and size control effects are insignificant, and when 100 parts by weight or more, side effects of changing the shape of the nanostructures are rather undesired.

Here, R ₅ , R ₆ , R ₇ and R ₈ are the same or different, represent a hydrocarbon group having 1 to 20 carbon atoms, and may include a hetero atom. And Y ⁻ represents an organic or inorganic anion.

Here, R represents a hydrocarbon group in the form of a single molecule or a polymer, and may include a heteroatom. And Y ⁻ represents an organic or inorganic anion.

Examples of the nitrogen compound represented by Formula 2a include tetrabutylammonium chloride, cetyltrimethylammonium bromide, tetrabutylphosphonium chloride, and the like. Examples of the sulfur compound represented by Formula 2b include sodium dodecyl sulfate and dodecylbenzenesulfonate. , Polystyrenesulfonate, poly (sodium-4-styrenesulfonate), and the like.

Using the techniques of the present invention, metal nanostructures of various shapes can be prepared by mixing and reacting ionic liquids, metal salts and reducing solvents.

In addition, in the polyol reduction reaction using a metal salt as a precursor, by selectively using an ionic liquid having a different kind of anion, metal nanoparticles having different shapes can be selectively and reproducibly produced.

Hereinafter, the present invention will be described in detail with reference to Examples, but the following Examples are merely illustrative for describing the present invention and do not limit the scope of the present invention.

Example 1

In a round bottom flask, 50 milliliters of a solution of AgNO ₃ dissolved in 0.1 mol of ethylene glycol and 50 milliliters of a solution of 1-butyl-3-methylimidazolium methyl sulfate in 0.15 mol of ethylene glycol was mixed. The mixed solution was reacted with stirring for 60 minutes at 160 degrees Celsius, and then cooled again to room temperature. The solution was filtered through a filter having a pore size of 1 micron, and observed with an electron scanning microscope to confirm that nanowires were formed as shown in FIG. 1. The diameter of the nanowires was about 220 nanometers and the length was observed to be about 7 microns.

<Example 2>

10 mL solution of AgNO ₃ dissolved in 0.2 mol of 1,3-propylene glycol in a round bottom flask 10 mL solution of 0.3 mL of 1-ethyl-3-methylimidazolium methyl sulfate dissolved in 1,3-propylene glycol Milliliters were mixed. The mixed solution was reacted by stirring for about 30 minutes at a temperature of 100 degrees Celsius, and then cooled to room temperature. The solution was filtered through a filter having a pore size of 1 micron, and observed with an electron scanning microscope to confirm that nanowires of about 180 nanometers in diameter and about 10 microns in length were formed.

 <Example 3>

10 mL of a solution of AgNO ₃ dissolved in 1,2-propylene glycol in a round-bottomed flask 10 mL of 0.3 mL of 1-ethyl-3-methylimidazolium methyl sulfate in 1,3-propylene glycol After milliliters were mixed, sodium dodecyl sulfate was added in an amount of 1% by weight of the added AgNO ₃ . The mixed solution was reacted by stirring for about 30 minutes at a temperature of 100 degrees Celsius, and then cooled to room temperature. The solution was filtered through a filter having a pore size of 1 micron, and observed with an electron scanning microscope to confirm that nanowires of about 80 nanometers in diameter and about 10 microns in length were formed.

<Example 4>

Example 4 A metal nanostructure was prepared in the same manner as in Example 1, except that 1-ethyl-3-methylpyridinium methyl sulfate was used as the ionic liquid. The solution was filtered through a filter having a pore size of 1 micron, and observed with an electron scanning microscope to confirm that nanowires were formed. The diameter of the nanowires was about 320 nanometers and the length was observed to be about 5 microns.

<Example 5>

Example 5 was a metal nanostructure was prepared in the same manner as in Example 1, except that 1-butyl-3-methylimidazolium chloride was used as the ionic liquid. Finally, the resulting reaction solvent was filtered through a 0.2 micron Teflon filter, and then observed with an electron scanning microscope. As shown in FIG. 2, silver nanoparticles having a cube shape of about 400 nanometers were formed.

<Example 6>

Example 6 A metal structure was prepared in the same manner as in Example 1 except that 1-butyl-3-methylimidazolium bromide was used as the ionic liquid. Finally, the resultant reaction solvent was filtered through a 1 micron filter, and then observed with an electron scanning microscope to confirm that silver particles having an octahedral shape of about 5 microns were formed as shown in FIG. 3.

1 to 3 are photographs showing metal nanostructures prepared according to the present invention.

Claims (13)

Metal nanostructure manufacturing method for producing metal nanostructures of various shapes by mixing and reacting an ionic liquid, a metal salt and a reducing solvent. The method of claim 1, wherein the shape structure of the metal nanostructure is determined by the chemical bonding structure of the cation and anion constituting the ionic liquid. The method of claim 2, wherein the ionic alkyl sulfate anionic components constituting the liquid with nanowires form by using an ionic liquid with an anion of a sulfur compound containing a (RSO ₄ ^{- -)} or alkyl sulfonate (RSO ₃₎ of the structure of such a one-dimensional shape, halide (halide) type anion by using an ionic liquid with a structure of three-dimensional shape, a chlorine anion (Cl ^{- -)} the form of a cube structure, and bromine anions (Br) for Method for producing a metal nanostructure, characterized in that to have an octahedral particle structure. The method of claim 3, wherein the ionic liquid is a compound composed of an organic cation and an organic or inorganic anion and is in the form of a single molecule or a polymer. The method of claim 4, wherein the ionic liquid is a compound composed of an organic cation and an organic or inorganic anion and is in the form of a single molecule or a polymer. [Claim 6] The metal nanostructure of claim 5, wherein the cation of the ionic liquid includes an imidazolium-based cation of Formula 1a and a pyridinium-based cation of Formula 1b. Manufacturing method. <Formula 1a>

R ₁ in Chemical Formula 1a And R ₂ are the same or different and represent hydrogen or a hydrocarbon group of 1 to 16 carbon atoms, and may include a heteroatom. And X ⁻ represents an anion of an ionic liquid. <Formula 1b>

R ₃ in Formula 1b And R ₄ are the same or different and represent hydrogen or a hydrocarbon group of 1 to 16 carbon atoms, and may include a heteroatom. And X ⁻ represents an anion of an ionic liquid. The method of claim 5, wherein the anion of the ionic liquid is ^{Br -, Cl -, I -} , BF 4 -, PF 6 -, ClO 4 -, NO 3 -, AlCl 4 -, Al 2 Cl 7 -, AsF 6 -, SbF 6 -, CH 3 COO -, CF 3 ^{_{COO -, CH 3 SO 3 -}} , C 2 H 5 SO 3 -, CH 3 SO 4 -, C 2 H 5 SO 4 -, CF 3 SO 3 -, (CF 3 SO 2) 2 N -, (CF 3 ^{_{SO 2) 3 C -, (}} CF 3 CF 2 SO 2) 2 N -, C 4 F 9 SO 3 -, C 3 F 7 COO -, (CF 3 SO 2) (CF 3 CO) N - containing Method for producing a metal nanostructure, characterized in that. The method of claim 1, wherein the metal salt is composed of a metal cation and an organic or inorganic anion, AgNO ₃ , Ag (CH ₃ COO) ₂ , AgClO ₄ , Au (ClO ₄ ) ₃ , PdCl ₂ , NaPdCl ₄ , PtCl _{2 ,} SnCl ₄ , HAuCl ₄ , FeCl ₂ , FeCl ₃ , Fe (CH ₃ COO) ₂ , CoCl ₂ , K ₄ Fe (CN) ₆ , K ₄ Co (CN) ₆ , K ₄ Mn (CN) _6, K ₂ CO ₃ Metal nanostructures manufacturing method characterized in that it comprises a. The method of claim 1, wherein the reducing solvent is a solvent such as diol, polyol or glycol having at least two hydroxyl groups in the molecule, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, glycerin, glycerol, polyethylene Method for producing a metal nanostructure, characterized in that containing glycol, polypropylene glycol. The method of claim 1, wherein the mixing ratio of the ionic liquid, the metal salt and the reducing solvent is 0.01 to 1 molar concentration of the metal salt and the ionic liquid (based on the repeating unit in the case of the polymer type ionic liquid) relative to the reducing solvent. Metal nanostructure manufacturing method characterized by the molarity. The method according to any one of claims 1 to 10, further comprising a nitrogen compound of Formula 2a and a sulfur compound of Formula 2b in addition to an ionic liquid, a metal salt, and a reducing solvent. <Formula 2a>

Here, R ₅ , R ₆ , R ₇ and R ₈ are the same or different, represent a hydrocarbon group having 1 to 20 carbon atoms, and may include a hetero atom. And Y ⁻ represents an organic or inorganic anion.  <Formula 2b>

Here, R represents a hydrocarbon group in the form of a single molecule or a polymer, and may include a heteroatom. And Y ⁻ represents an organic or inorganic anion. 12. The method of claim 11, wherein the concentration of the nitrogen compound and the sulfur compound is 0.1 to 100 parts by weight based on 100 parts by weight of the metal salt. Metal nanostructures prepared using the method of claim 1 to claim 10.

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