KR20180068538A - Method for synthesis of Copper nanowires including dimension manipulation of Copper nanostructures - Google Patents

Abstract

The present invention relates to a synthesis method of a copper nanowire capable of adjusting a size of a copper nanostructure and surface quality by an interaction of a cationic surfactant (CTAB) and ethylene diamine (EDA) based on a solution method. Ethylene diamine (EDA), sodium hydroxide (NaOH), copper nitrate (Cu(NO_3)_2), and a cationic surfactant (CTAB) are included. A reaction time with a quantity is adjusted based on an interaction of the ethylene diamine (EDA) and the cationic surfactant (CTAB) to adjust a size of a copper nanostructure and surface quality.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of synthesizing copper nanowires,

The present invention relates to a method of synthesizing metal nanowires, and more particularly, to a copper nanowire synthesis method capable of controlling the size and surface quality of copper nanostructure through interaction of CTAB and EDA based on a solution method.

Indium Tin Oxide (ITO) is widely used as a transparent conductor because it has a low sheet resistance (90% transmittance, 10 < / RTI > sq-1).

However, the main raw material for ITO is indium, which is almost depleted, and gaso-ITO film lamination is inefficient, so the price of ITO film has risen about ten times over the past decade.

Moreover, since ITO breaks well, it is not suitable for flexible devices. For this reason, a lot of research is being done to find cheap and flexible alternative materials. Graphene, single-walled carbon nanotube networks, metal nanowires, doped zinc oxide films, and PEDOT: PSS are typical candidates of interest.

The metal nanowire network film also attracted a great deal of attention because of its unique structure, good performance and good processability. Silver-coated films showed a sheet resistance of 20 Ω sq-1 at 95% transmittance, which is close to the performance of ITO films. The performance of the copper nanowire network film is slightly less than that of the silver nanowire film.

For example, the conductivity of a copper nanowire network film is about 6% lower than that of a silver nanowire film under the same transmission conditions. However, copper is 100 times cheaper than silver, and copper nanowires can be synthesized faster than silver nanowires, which can dramatically lower manufacturing costs.

However, a solution method capable of more precisely controlling the size and quality of the copper nanostructure can be used to improve the industrial applicability.

Prior art patents related to the synthesis of copper nanowires were KR 10-1535014, KR 10-1305710, KR 10-1076523, KR 10-1073EDA8, JP 5733548, etc. Specific solutions for controlling the size and surface roughness of nanostructures Configuration, and effect of the present invention.

The present invention provides a copper nanowire synthesis method capable of controlling the size and quality of copper nanowires in a solution process step through the interaction of CTAB and EDA.

),질산구리(

) 및 양이온성 계면활성제(CTAB)를 포함하되, 상기 에틸렌다이아민(EDA)과 양이온성 계면활성제(CTAB)의 양과 농도를 조절하여 혼합한 제1혼합액을 교반하는 제1단계;상기 제1혼합액에 하이드라진(

)을 첨가한 제2혼합액을 교반하는 제2단계; 상기 제2혼합액을 원심분리 및 상층액을 디캔팅하는 제3단계;상기 제3단계에서 생성되는 구리나노구조를 하이드라진 수용액에 분산시키는 제4단계; 및 상기 제4단계에서 합성된 구리나노구조를 하이드라진 수용액에 저장하는 제5단계; 를 포함하는, 구리 나노구조의 크기 조절이 가능한 구리 나노선의 합성방법을 제공한다.The present invention relates to a process for the preparation of a composition comprising ethylene diamine (EDA), sodium hydroxide

), Copper nitrate

And a cationic surfactant (CTAB), wherein the first mixed liquid is prepared by mixing the ethylene diamine (EDA) and the cationic surfactant (CTAB) Hydrazine (

A second step of stirring the second mixed solution added thereto; A third step of decanting the second mixed solution and decanting the supernatant, a fourth step of dispersing the copper nanostructure formed in the third step in an aqueous solution of hydrazine, And a fifth step of storing the copper nanostructure synthesized in the fourth step in an aqueous solution of hydrazine; And a method of synthesizing copper nanowires capable of controlling the size of the copper nanostructure.

At this time, it is preferable that the first step is charged up to a critical amount where the effect of the cationic surfactant (CTAB) becomes saturated.

According to another aspect of the present invention, there is provided a copper nanowire synthesized by a copper nanowire synthesis method according to the present invention and a copper nanowire network film using the same.

According to the present invention, it is possible to easily control the size and surface roughness of the copper nanostructure in the solution process step, thereby enabling mass production of high-quality copper nanowires economically and maximizing the industrial applicability of copper nanowires.

1 is a process flow diagram of a copper nanowire synthesis method according to the present invention.
Fig. 2 is a SEM image and a graph showing a change in copper nanowire according to the amount of CTAB.
Figure 3 illustrates the interaction between EDA and CTAB.
FIG. 4 shows XRD pattern changes with and without CTAB.
FIG. 5 is a photograph showing the change with time of CTAB and reaction time and UV-Vis absorption graph. FIG.
6 is a graph showing changes in the diameter and length of nanostructures according to CTAB presence and reaction time.
Figure 7 is a comparative photograph of nanoparticles synthesized by reacting CTAB with different amounts of HDA.
8 is a graph showing the results of light transmittance of two copper nanowire network films synthesized differently depending on the presence or absence of CTAB.

Copper nanowires (CuNWs) according to the present invention are synthesized by a solution method in which the amount of CTAB is changed to a critical value based on the interaction between cationic surfactant CTAB (cetyltrimethyl ammonium bromide) and EDA, do.

Hereinafter, the technical features of the present invention will be described in detail with reference to the drawings and experimental procedures leading to the present invention.

FIG. 1 is a flow chart of a copper nanowire synthesis method according to the present invention. FIG. 1 is a flow chart illustrating a method of synthesizing copper nanowires according to the present invention, which includes a first mixed solution stirring step (s10), a second mixed solution stirring step (s20), a copper nanostructure separation step (s30) And a copper nanostructure storage step (s50).

),질산구리(

) 및 양이온성 계면활성제(CTAB)를 포함한 제1혼합액을 교반하는 단계로서, 상기 EDA와 CTAB의 양과 농도를 조절함으로써 구리 나노선(CuNWs)의 합성뿐만 아니라 직경, 길이 및 표면의 품질까지 조절할 수 있고, 상기 제1혼합액을 80℃에서 3분간 200rpm으로 교반한다.The first mixed solution stirring step (s10) is a step of mixing ethylene diamine (EDA), sodium hydroxide

), Copper nitrate

) And a cationic surfactant (CTAB), and adjusting the amount and concentration of the EDA and the CTAB to control not only the synthesis of copper nanowires (CuNWs) but also the diameter, length and surface quality And the first mixed solution is stirred at 80 rpm for 3 minutes at 200 rpm.

) 20mL 및 0.2M의 질산구리 (

) 1mL 및 0.0169M의 양이온성 계면활성제(CTAB) 0.13g의 비율로 혼합될 수 있으며, 0.0169M이라는 작은 농도의 CTAB에서 구리나노선의 직경과 길이는 각각 55%와 43%까지 감소되었다. The copper nanowires (CuNWs) are the thinnest and shortest when the CTAB is applied to the critical amount where the effect becomes saturated, which is possible only in the interaction with the EDA. According to the experimental example, the first step is a step of adding 0.15 mL of 0.111 M of ethylenediamine (EDA), 15 M of sodium hydroxide

) And 20 mL of 0.2 M copper nitrate

) And 0.13 g of 0.0169 M cationic surfactant (CTAB), and the diameter and length of the copper nanowires were reduced to 55% and 43%, respectively, in a small concentration of 0.0169 M CTAB.

)을 첨가한 제2혼합액을 교반하는 과정인데, 상기 제2혼합액을 80℃까지 가열하여 60분간 200rpm으로 교반한다. The second mixed solution stirring step s20 is a step of mixing hydrazine (

). The second mixed solution is heated to 80 DEG C and stirred at 200 rpm for 60 minutes.

The copper nanostructure separation step (s30) is a step of centrifuging the second mixed solution and decanting the copper nanostructure by decanting the supernatant. The second mixed solution is centrifuged at 5,000 rpm for 5 minutes, and the supernatant is decanted This process is repeated three times.

In the copper nanostructure dispersion step (s40), the second mixed solution having been subjected to the centrifugal separation and decanting process is dispersed in a 3 wt% hydrazine aqueous solution by vortexing for 30 seconds, and the copper nanostructure storage step (s50) By storing in a 3 wt% hydrazine solution at room temperature, the copper nanowires (CuNWs) are completed in the synthesis process.

According to another aspect of the present invention, there is provided a copper nanowire synthesized by the above-described method and a copper nanowire network film using the copper nanowire, which belong to the scope of the present invention if the copper nanowire synthesis method is the same .

Experiments leading to the present invention proceeded as follows. In order to test the influence and interaction of CTAB and EDA, which are technical features of the present invention, the results were compared and analyzed through various embodiments in which CTAB was not added or mixed in the mixed solution.

1. Solution for synthesis of copper nanostructure

(15M, 20mL) 및

(0.2M, 1mL)에 CTAB를 넣거나 넣지 않는 다양한 방법으로 50mL 유리병에 혼합되어, 80℃에서 3분간 200rpm의 속도로 섞이고

(35wt%,0.025mL)가 첨가되었다. EDA (0.111 M, 0.15 mL),

(15 M, 20 mL) and

(0.2 M, 1 mL) were mixed in a 50 mL glass bottle with or without CTAB in various ways and mixed at 80 ° C for 3 minutes at 200 rpm

(35 wt%, 0.025 mL) was added.

The mixed solution was heated to 80 ° C., stirred at 200 rpm for 60 minutes, and the amount of CTAB was varied in the range of 0 to 0.26 g to examine the effect on copper nanostructure.

After the reaction, the suspension (suspension) was centrifuged at 5000 rpm for 5 minutes and the supernatant was decanted from the nanostructure. The nanostructures were then dispersed in a 3 wt% hydrazine aqueous solution by vortexing for 30 seconds. This centrifugation and decanting procedure was repeated three times. The final copper nanostructure was stored in a 3 wt% hydrazine solution at room temperature.

(15M, 20mL) 및

(02M, 1mL) 및

(35wt%,0.025mL)이 이어서 첨가되었다. 그 혼합된 용액은 80℃까지 가열되었고, 그 온도에서 60분간 200rpm으로 교반되었다. 세정(디캔팅)과 원심분리 단계는 상술한 설명과 같다. In addition, to reveal the difference between HDA and EDA, 0.0416 g and 0.208 g of HDA were mixed with a fixed amount (0.13 g) of CTAB in a 50 mL glass bottle instead of EDA and stirred at 80 rpm for 3 minutes at 200 rpm. And

(15 M, 20 mL) and

(02M, 1 mL) and

(35 wt%, 0.025 mL) was then added. The mixed solution was heated to 80 DEG C and stirred at that temperature for 60 minutes at 200 rpm. The steps of decanting and centrifuging are as described above.

The various experimental conditions including the above solution method are summarized in Table 1.

<Table 1>

2. Experimental observation

EXP . 1 (Interaction of CTAB and EDA)

FIG. 2 shows SEM images of each copper nanowire synthesized when the amount of CTAB was changed based on the solution method from A1 to A4 in Table 1. FIG. All other experimental conditions remained constant. (a), no CTAB was injected and the average diameter and length of the copper nanowires were measured at ~ 400 nm and ~ 14 μm, indicating a two magnitude increase over the normal composition.

Most notably, (a) - (d), the diameter of the copper nanowire clearly decreases with increasing CTAB amount. This decrease in nanowire diameter involves a decrease in nanowire length.

(e), the average diameter and length of the copper nanowires decrease as the amount of CTAB added to the solution increases, and when the critical value is reached, the effect tends to saturate. That is, increasing the CTAB to this threshold substantially reduces both the diameter and the length of the copper nanowire.

In this experiment, the threshold of CTAB was 0.13 g (0.0169 M), and the average diameter and length of the copper nanowires were approximately 180 nm and 8 μm at the above-mentioned thresholds, because the diameter and length of the copper nanowires Which means 55% and 43% respectively.

The substantial reduction in nanowire size appears to be due to the interaction between CTAB and EDA.

EDA with a negative terminal group is preferentially absorbed into the high energy side of the copper crystals to interfere with the adsorption of copper atoms, while the low energy growth side remains open and copper atoms can adsorb. This is why copper nanowires become thinner at higher EDA concentrations.

)로 이루어져 있다.CTAB is a typical amphipathic surfactant with long chain alkyl and cation head groups (

).

The cationic head group of CTAB is likely to be electrostatically bonded to the polar atomic group of EDA already absorbed on the side of the growing copper nanowire.

This is because CTAB molecules at high concentrations have a protective effect on the nanowire side of the nanowire and inhibit the radial growth of nanowires.

The effect of CTAB is saturated when the critical concentration is exceeded, and the side is completely stabilized by CTAB.

Both EDA and CTAB can be absorbed at the ends of copper nanowires and can contribute to the reduction of nanowire length.

Another effect of CTAB is that the surface morphology of the copper nanowires becomes smooth as the CTAB concentration increases ((a) -> (d)). This is because as CTAB increases, it can effectively suppress local and random radial growth.

Reduced nanowire size and improved surface quality are the result of the interaction of EDA and CTAB, and Figure 3 graphically illustrates this compared to EDA alone.

XRD measurements can be used to examine changes in crystal structure and crystallinity. Figure 4 shows the XRD patterns of copper nanowires with and without CTAB. All other synthesis conditions here are the same as in Fig. 2 and both samples exhibit a sharp and similar diffraction pattern and are perfectly compatible with the face-centered cubic lattice crystal structure of copper.

It can be seen that the CTAB blend does not deteriorate the quality of the copper crystals when the three peak points (2? = 43.2, 50.3, 74.1 ° (111,200,220)) coincide.

EXP . 2 ( CTAB  And reaction time)

In order to better understand the copper nanowire growth process, early stage nanowire growth was examined by emphasizing the differences caused by CTAB. Therefore, the comparison between the case where CTAB is not used and the case where a critical amount (0.13 g) of CTAB is added is compared. FIG. 5 is a photograph of the precursor solution (a) and solutions (c, d) reacted for a different time after addition of hydrazine to the precursor solution.

의 형성에 의한 것으로 알려져 있다. 구리 착물의 존재를 확인하기 위해서, UV-Vis 흡수 테스트가 수행됐다. 광범위한 흡수 피크가 (b)에 나타난 바와 같이 650nm에서 중심을 이루었고 이는

착물이 전구체 용액에서 생성되었음을 의미한다.(a), the initial precursor solution is deeply colored

And the like. To confirm the presence of the copper complex, a UV-Vis absorption test was performed. The broad absorption peaks were centered at 650 nm as shown in (b)

Means that the complex was formed in the precursor solution.

착물은 하이드라진 첨가에 따라

의 산화에 의한

의 형성을 통해 Cu(I)로 환원되는 것으로 추정한다. From (c) and (d), the deep blue color begins to discolor from the moment hydrazine is added to the solution and turns white or semitransparent in 5 minutes. Experimental

The complexes are prepared by hydrazine addition

By oxidation of

To form Cu (I).

착물을 포함하는 용액은 거의 투명해 보인다. CTAB 없는 용액이 흰 것은

나노입자와

착물과 같은 다른 물질의 포함을 의미한다. According to this reduction result,

The solution containing the complex appears almost transparent. White solution without CTAB

Nanoparticles

&Lt; / RTI &gt; complexes and complexes.

As the reaction continues, both solutions undergo a similar discoloration of green (5-8 minutes) and red (9-10 minutes). At 20 minutes, a suspension of a dark red copper nanowire complex is clearly observed on the surface of both solutions. The appearance of this material is similar to that seen in the reacted solution for 60 minutes and indicates that the nanowire growth is almost complete.

For more assured analysis, the time-dependent size of the nanowires is shown in FIG.

Regardless of CTAB, both the length and diameter of the copper nanowire follow a two-stage growth mode related to the reaction time.

이온의 한정된 공급에 기인한다. In the first stage, the nanowire grows rapidly to a primary subordinate over time, and the nanowire growth rate decreases over the critical time,

Due to limited supply of ions.

And the size of the nanowire is very slowly approaching the nanowire that has grown for 60 minutes. The response threshold time for adopting CTAB is about 10 minutes, which is half of that without CTAB.

착물 환원 과정에 관련된다는 것을 의미한다. This suggests that the introduction of CTAB could promote nanowire growth, perhaps stabilizing copper nanostructures anisotropically

Which is related to the complex reduction process.

As shown in FIGS. 6 (a) and 6 (b), at the same reaction time, many nanoparticles appeared in the solution without CTAB, whereas most of the solution containing CTAB formed copper nanowires.

EXP . 3 (EDA and HDA  Difference)

Another form of additive HDA (Hexadecylamine) is added to the solution with CTAB as an alternative to EDA.

,

, Cu와 같은 다양한 금속 나노구조를 합성하는 캡핑제로 사용되며, 극성 아민기와 비극성 알킬 체인 때문에 본래 양친매성이다. HDA

,

, Cu, and is inherently amphiphilic because of polar amine groups and nonpolar alkyl chains.

EDA is mainly used as a capping agent in the synthesis of copper nanowires (CuNWs), and HDA is presumed to play a similar role.

FIG. 7 shows an SEM image of a copper nanostructure synthesized by varying the amount of HDA (0.0416 g, 0.208 g) in a fixed amount (0.13 g) of CTAB, wherein the average diameters of copper nanoparticles were measured at 600 nm and 450 nm, respectively .

Unlike the combination of CTAB and EDA, the combination of CTAB and HDA generates copper nanoparticles.

This type of difference is presumed to be responsible for the isotropic absorption of HDA compared to EDA, which results in the formation of an isotropic protective layer of copper nanostructures by CTAB, which is why copper nanoparticles It is easy to create.

EXP . 4 (improved light transmittance)

Copper nanowires (CuNWs) can be applied to flexible electrodes, and the optical transmittance of the copper nanowire network film is a very important factor in practical use. Optical transmittance is known to improve as the copper nanowire size decreases.

Figure 8 shows the transmittance spectra of two copper nanowire films deposited on a PET substrate.

Thin, short copper nanowires synthesized by adding 0.13 g of CTAB and long and thick copper nanowires (synthesized under standard conditions without CTAB) were selected as comparative samples.

Thin and short copper nanowires have a higher light transmittance than long and thick copper nanowires, with transmittances of 79% and 73% at 550 nm, respectively.

Therefore, if the size reduction of copper nanowires occurs with the aid of CTAB, the light transmittance of the nanowire film is improved and the light blocking effect is reduced.

3. Conclusion

The conventional solution method uses copper nitrate, EDA and hydrazine as main reaction materials, and the resultant nanowire is coarse and the surface is rough.

The present invention confirms that the interaction between CTAB and EDA effectively reduced the diameter of the nanowire and smoothed the surface of the nanowire.

This effect was due to the complete inhibition of growth on the side of the nanowire by CTAB and its effect was found to be saturated at the critical concentration of CTAB. These results provide an important clue to manipulate copper nanostructures and sizes on a solution-based basis.

s10: first mixed solution stirring step s20: second mixed solution stirring step
s30: copper nanostructure separation step s40: copper nanostructure dispersion step
s50: Copper nanostructure storage step

Claims (11)

Ethylene diamine (EDA), sodium hydroxide (

), Copper nitrate

And a cationic surfactant (CTAB), wherein the amount of the ethylenediamine (EDA) and the amount of the cationic surfactant (CTAB) are controlled and the first mixture is stirred;
To the first mixed liquid was added hydrazine (

A second step of stirring the second mixed solution added thereto;
Centrifuging the second mixed solution and decanting the supernatant;
A fourth step of dispersing the copper nanostructure formed in the third step in an aqueous solution of hydrazine; And
A fifth step of storing the copper nanostructure synthesized in the fourth step in an aqueous solution of hydrazine; Wherein the size of the copper nanostructure is adjustable. The method according to claim 1,
Wherein the first step is charged to a critical amount where the effect of the cationic surfactant (CTAB) is saturated, wherein the size of the copper nanostructure can be controlled. The method according to claim 1,
Wherein the first step is a step of stirring the first mixed solution at 80 DEG C for 3 minutes at 200 rpm, whereby the size of the copper nanostructure can be controlled. The method according to claim 1,
Wherein the second step is a step of heating the second mixed solution to 80 캜 and stirring at 200 rpm for 60 minutes, wherein the size of the copper nanostructure can be controlled. The method according to claim 1,
Wherein the third step comprises centrifuging the second mixed solution at a rotation speed of 5,000 rpm for 5 minutes and decanting the supernatant, wherein the size of the copper nanostructure is adjustable. The method according to claim 1,
Wherein the third step comprises repeating the centrifugal separation and the decanting process three or more times, wherein the size of the copper nanostructure can be controlled. The method according to claim 1,
Wherein the fourth step is a step of dispersing the second mixed solution in a 3 wt% hydrazine aqueous solution by vortexing for 30 seconds, whereby the size of the copper nanostructure can be controlled. The method according to claim 1,
Wherein the fifth step is to store the copper nanostructure in an aqueous solution of hydrazine at room temperature, wherein the size of the copper nanostructure can be controlled. The method according to claim 1,
In the first step, 0.15 mL of 0.111 M ethylenediamine (EDA), 15 M sodium hydroxide

) And 20 mL of 0.2 M copper nitrate

) And 0.13 g of a cationic surfactant (CTAB) of 0.0169 M, wherein the size of the copper nanostructure is adjustable. A copper nanowire synthesized by the method of any one of claims 1 to 9. A copper nanowire network film using copper nanowires synthesized by the method of any one of claims 1 to 9.

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