KR101337412B1 - Manufacturing method for metal nanowire in room temperature and aqueous media - Google Patents

Abstract

The present invention relates to a method for producing a metal nanowire of a constant length in a room temperature, poly (sodium 4-styrenesulfonate) aqueous solution, the present invention to produce a metal nanowire even at a very low temperature compared to the prior art through the manufacturing method. This makes it possible to produce metal nanowires in a manageable aqueous medium rather than anhydrous polyol medium, and also to produce highly reproducible metal nanowires with very uniform length and aspect ratio.

Description

Manufacturing method for metal nanowire in room temperature and aqueous media

The present invention relates to a method for producing a metal nanowire, and more particularly to a method for manufacturing a metal nanowire of a constant length in a poly (sodium 4-styrenesulfonate) aqueous solution at room temperature.

Metal nanostructures having a one-dimensional shape, particularly silver nanowires having high aspect ratios, have been used for the production of conductive films, electrodes and other nanostructures due to their excellent optical properties and electrical conductivity.

Recently, a technique for producing metal nanowires has been reported by using polyols including ethylene glycol as reducing agents in the presence of polyvinylpyrrolidone [Chem. Mater. 14, 4736-4745. The technique has an advantage that the metal nanostructure can be relatively easily prepared on a solution basis through a reaction that can be referred to as a "polyol reduction method." However, the above method requires a high reaction temperature of 150 ° C. or higher, and it is cumbersome to operate by non-aqueous reaction using anhydrous polyol such as ethylene glycol. Structures having the shape of nanoparticles as well as wires are often mixed, and there is a disadvantage that the shape of the nanostructures is difficult to be reproducibly produced according to reaction conditions.

On the other hand, a method of preparing silver nanowires under an aqueous medium has been reported to use ionic surfactants such as cetyltrimethylammonium bromide and sodium dodecyl sulfate or citric acid. It was impossible.

The present invention provides a method for producing metal nanowires having a very low reaction temperature at room temperature, preparing metal nanowires under an aqueous medium, and having uniform aspect ratios and lengths in a uniform and reproducible manner.

The present invention provides a method for producing a metal nanowire comprising the step of adding a metal nanoparticle seed solution, a metal salt, and a reducing agent to a poly (sodium 4-styrenesulfonate) aqueous solution to stir to form a metal nanowire.

In the present invention, the concentration of the poly (sodium 4-styrenesulfonate) is preferably 20 to 50 mM. When the concentration of poly (sodium 4-styrenesulfonate) is below the lower limit, only a mixture of amorphous polydispersed nanoparticles is formed, and when the upper limit is exceeded, a complicated entangled network structure may be formed.

In the present invention, the number average molecular weight of the poly (sodium 4-styrenesulfonate) is 50,000 to 100,000, preferably 60,000 to 80,000. If it is out of the above range, the metal nanowire may not be formed.

In the present invention, the metal salt is composed of a metal cation and an organic or inorganic anion, and may be any one selected from AgNO ₃ , Ag (CH ₃ COO) ₂ , AgClO ₄ , Au (ClO ₄ ) ₃ , PdCl _2, and PtCl ₂ . have. The concentration of the metal salt is 0.01 to 0.3 mM, preferably 0.05 to 0.2 mM.

In the present invention, the reducing agent may be any one selected from ascorbic acid, sodium citrate, sodium borohydride and hydroquinone.

The method for producing a metal nanowire of the present invention may be performed at room temperature, unlike the conventional polyol reduction method performed at 150 ° C. or higher and at least 100 ° C. In the present invention, the room temperature means 1 to 60 ° C, preferably 2 to 45 ° C, more preferably 3 to 35 ° C. In particular, in the present invention, metal nanowires may be produced without performing a separate heating operation. have.

Preparation of the metal nanowire of the present invention may be carried out by reaction for 2 to 60 minutes, preferably 3 to 30 minutes, more preferably 5 to 15 minutes in the above conditions.

Metal nanowires produced through the method of the present invention is a constant 40 to 60 nm in diameter, the length is adjustable from 0.5 to 2.5 ㎛, the aspect ratio is 10 to 50.

In the method of preparing the metal nanowires according to the present invention, a metal nanowire is prepared by adding a metal nanoparticle seed solution, a metal salt, and a reducing agent to a poly (sodium 4-styrenesulfonate) aqueous solution, followed by stirring to prepare a metal nanowire. Metal nanowires may be obtained by washing and filtering with purified water that does not contain Nate).

The length of the metal nanowire of the present invention can be adjusted by adjusting the concentration of the poly (sodium 4-styrenesulfonate) aqueous solution within the range of 0.5 to 2.5 ㎛. When the concentration of poly (sodium 4-styrenesulfonate) is low, the length of the nanowire is short, and when the concentration of poly (sodium 4-styrenesulfonate) is increased, the length of the nanowire is extended in proportion to the concentration.

According to the present invention, the metal nanowires can be produced at a very low temperature at room temperature compared to the conventional method, and the metal nanowires can be manufactured in an easy-to-use aqueous medium rather than anhydrous polyol medium, and also have a length and aspect ratio. Highly uniform metal nanowires can be produced with high reproducibility.

1 is a photograph showing the color change according to the reaction time of the poly (sodium 4-styrenesulfonate) reaction solution.
FIG. 2A is an SEM photograph of the silver nanowires obtained in Preparation Example 1, FIG. 2B is a photograph of the terminal cross section of the silver nanowires, FIG. 2C is a photograph showing the lateral pentagonal shape of the silver nanowires, and FIG. X-ray diffraction analysis pattern, Figure 2E is a selective region electron diffraction (SAED) pattern.
FIG. 3A shows a photograph of silver nanowires prepared with a concentration of poly (sodium 4-styrenesulfonate) in Preparation Example 1 at 20 mM, FIG. 3B at 30 mM, FIG. 3C at 40 mM, and FIG. 3D at 50 mM. 3E is a graph showing the correlation between the concentration of poly (sodium 4-styrenesulfonate) and the length of silver nanowires.
Figure 4 is a spectrum of the ultraviolet-visible region of the silver nanowires prepared in poly (sodium 4-styrenesulfonate) aqueous solution of 20 mM to 50 mM in Preparation Example 1.
5A is a scanning electron micrograph of the nanostructure prepared under the 10 mM poly (sodium 4-styrenesulfonate) aqueous solution of Comparative Example 1, and FIG. 5B is the 80 mM poly (sodium 4-styrenesulfonate) aqueous solution of Comparative Example 2 Below is an electron scanning micrograph of the prepared nanostructures.
6 is an electron scanning micrograph of the nanostructure prepared without adding the silver nanoparticle seed solution of Comparative Example 3.
FIG. 7 is an electron scanning micrograph of silver nanostructures having different final concentrations of AgNO ₃ in Comparative Examples 4 to 7. FIG.
FIG. 8A is a photograph of silver nanostructures when the number average molecular weight of poly (sodium 4-styrenesulfonate) is 200,000, and FIG. 8B is 1000,000.

Hereinafter, the contents of 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.

Manufacturing example  One

1) Preparation of silver seed solution

0.6 mL of a 10 mM aqueous sodium borohydride solution was injected into a mixed solution of 10 mL of 0.5 mM AgNO ₃ aqueous solution and 10 mL of 0.5 mM trisodium citrate, and stirred for 30 seconds. The stirred seed solution was incubated for 2 hours before use.

2) Preparation of Silver Nanowires

21.7, 32.5 and 43.3, respectively. 1 mL of the silver seed solution was added to 372 mL of an aqueous solution of poly (sodium 4-styrenesulfonate) having a number average molecular weight of 70,000 of 54.2 mM, and 10 mL of 8 mM AgNO ₃ aqueous solution and 20 mL of 100 mM ascorbic acid were mixed. After preparing the reaction solution and stirred for 10 minutes at room temperature (25 ℃) to prepare the silver nanowires of Examples 1 to 4, respectively. At this time, the final concentration of poly (sodium 4-styrenesulfonate) in each reaction solution was 20, 30, 40, 50 mM, the final concentration of AgNO ₃ was 0.2 mM.

The reaction solution was confirmed to be a yellowish opaque solution indicating the growth of silver nanowires after the start of stirring. The color change of the reaction solution according to the reaction time is shown in FIG. 1.

After 10 minutes, the reaction solution containing silver nanowires was centrifuged, and the precipitate was washed with water containing Tween 20 to remove poly (sodium 4-styrenesulfonate), AgNO ₃ , and ascorbic acid remaining after the reaction. Removed.

Experimental Example  One: Manufacturing example  1 silver Nano-ray  characteristic

An electron scanning microscope (SEM) photograph of the silver nanowire (Example 2) obtained in the 30 mM poly (sodium 4-styrenesulfonate) aqueous solution through the procedure of Preparation Example 1 is shown in Figure 2A. The prepared silver nanowires had a uniform diameter of 50 nm as a one-dimensional structure. In addition, the terminal cross section of the prepared silver nanowires showed a pentagonal shape produced by twin boundaries of seeds (FIG. 2B). The pentagonal cross section of the silver nanowire was confirmed that the side surface of the silver nanowire consists of a pentagonal column shape having five sides (FIG. 2C). In addition, four diffraction peaks shown in the X-ray diffraction analysis pattern of FIG. 2D show that the silver nanowires are composed of pure silver, and have a face-centered-cubic (fcc) crystal structure. In addition, the selective area electron diffraction (SAED) pattern of FIG. 2E shows polycrystalline polycrystalline nanowires.

Experimental Example  2: Poly (Sodium 4- Styrenesulfonate ) Depending on the concentration Nano-ray  length adjusting

In Example 1, the concentration of poly (sodium 4-styrenesulfonate) was adjusted from 20 mM to 50 mM, and it was confirmed that the length of the silver nanowires was adjusted from 0.5 μm to 2.5 μmRkwl in proportion to the concentration.

FIG. 3A shows a photograph of silver nanowires prepared with a concentration of poly (sodium 4-styrenesulfonate) at 20 mM, FIG. 3B at 30 mM, FIG. 3C at 40 mM, and FIG. 3D at 50 mM. FIG. It is a graph showing the correlation between the concentration of (sodium 4-styrenesulfonate) and the length of silver nanowires.

According to FIGS. 3A to 3D, regardless of the concentration change of the poly (sodium 4-styrenesulfonate), the diameter of the silver nanowires is constant at 50 mM, and it can be seen that silver nanowires having a constant size are formed according to the concentration.

Experimental Example  3: silver Nano-ray  Change in absorbance with length

In Preparation Example 1, the spectrum of the ultraviolet-visible ray region of the silver nanowires prepared in the poly (sodium 4-styrenesulfonate) aqueous solution of 20 mM to 50 mM is shown in FIG. 4.

In the silver nanowires having the lowest aspect ratio of 10 or less, the maximum peaks were confirmed at 409 nm and 504 nm, respectively, and as the aspect ratio was increased, the peaks increased rapidly at first and then decreased at 409 nm, and 504 nm. In the case of plasmon of, as the aspect ratio increases, the peak increases and the shift to the red region occurs.

Comparative Example  1 and 2

The content and conditions of the material different from Example 2 of Preparation Example 1 were prepared in the same manner to prepare a silver nanostructure, but only the poly (sodium 4-styrenesulfonate) concentration of the reaction solution was adjusted to 10 mM and 80 mM, respectively, Comparative Example 1 And silver nanostructures of 2 were prepared.

Experimental Example  4: Comparative Example  Electron scanning micrographs of nanostructures 1 and 2

Under 10 mM poly (sodium 4-styrenesulfonate) aqueous solution of Comparative Example 1, only a mixture of amorphous polydispersed nanoparticles was formed (FIG. 5A), and 80 mM poly (sodium 4-styrene) of Comparative Example 2 Sulfonate) formed an intricate mesh structure under aqueous solution (FIG. 5B).

Comparative Example  3

The content and conditions of the material different from Example 2 of Preparation Example 1 were prepared in the same manner, but the silver nanostructure of Comparative Example 3 was prepared without adding silver nanoparticle seed solution.

Experimental Example  4: Comparative Example  Electron Scanning Microscopy of Nanostructures of Part III

6 shows an electron scanning micrograph of the nanostructure prepared without adding the silver nanoparticle seed solution of Comparative Example 3. FIG. When the silver nanoparticle seed solution was not added, silver nanoparticles of irregular shape and size were formed, and some nanowires were produced, but were much thinner than in Preparation Example 1 and the yield was significantly lower.

Comparative Example  4 to 7

The content and conditions of the material different from Example 2 of Preparation Example 1 were prepared in the same manner, but the final concentration of AgNO ₃ added to the reaction solution was adjusted to 0.5 mM, 1 mM, 1.5 mM, and 2 mM, respectively. Silver nanostructures of Examples 4 to 7 were prepared.

Experimental Example  5: Comparative Example  4 To 7  Electron scanning micrograph of nanostructure

Electron scanning micrographs of silver nanostructures having different final concentrations of AgNO ₃ of Comparative Examples 4 to 7 are shown in FIG. 7. 7A is a photograph of silver nanostructures when the final concentration of AgNO ₃ is 0.5 mM, FIG. 7B is 1 mM, FIG. 7C is 1.5 mM, and FIG. 7D is 2 mM. The final concentration of AgNO _{3 in} the reaction solution is 0.5 mM or more. In the case it can be seen that it does not form a silver nanowire.

Comparative Example  8 and 9

The content or condition of the material different from Example 2 of Preparation Example 1 was prepared in the same manner, except that the number average molecular weight of the poly (sodium 4-styrenesulfonate) is 200,000 and 1,000,000, respectively, Comparative Example 8 and Nine silver nanostructures were prepared.

Experimental Example  6: Comparative Example  Electron scanning micrographs of nanostructures 8 and 9

Electron scanning micrographs of silver nanostructures having different number average molecular weights of poly (sodium 4-styrenesulfonate) of Comparative Examples 8 and 9 are shown in FIG. 8. FIG. 8A is a photograph of silver nanostructures when the number average molecular weight of poly (sodium 4-styrenesulfonate) is 200,000, and FIG. 8B is a photograph of the silver nanostructure when the number average molecular weight of poly (sodium 4-styrenesulfonate) is In the case of 200,000 or more, it could be seen that the silver nanowires could not be formed.

Claims (9)

Forming a metal nanowire by adding a metal nanoparticle seed solution, a reducing agent and a 0.01 to 0.3 mM metal salt to a 20 to 50 mM aqueous solution of poly (sodium 4-styrenesulfonate) having a number average molecular weight of 50,000 to 100,000 Method of producing a metal nanowire comprising a.
delete delete 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 and PtCl ₂ Method for producing a metal nanowire, characterized in that one.
delete The method of claim 1, wherein the reducing agent is any one selected from ascorbic acid, sodium citrate, sodium borohydride and hydroquinone.
The method of claim 1, wherein the production method of the metal nanowires, characterized in that carried out at room temperature.
The method of claim 1, wherein the metal nanowire is produced for 2 to 60 minutes.
In the 20-50 mM aqueous solution of poly (sodium 4-styrenesulfonate) having a number average molecular weight of 50,000 to 100,000, a metal nanoparticle seed solution, a reducing agent and 0.01 to 0.3 mM metal salt were added to form a metal nanowire by stirring. And controlling the concentration of the poly (sodium 4-styrenesulfonate) aqueous solution.

Images