KR101864692B1 - Microfluidic reactor and method for preparing of metal nanoparticle using the same - Google Patents

Abstract

The present invention relates to a method for preparing metal nanoparticles using a microfluidic reactor, and more particularly, to a droplet-based microfluidic reactor and metal nanoparticles produced thereby. The droplet-based microfluidic reactor according to the present invention can be manufactured in a simple and economical manner by including a static mixer and a T-shaped contactor, and can produce silver nanoparticles of a uniform size in a simple and environmentally friendly manner in a short period of time There is an effect that can be done.

Description

TECHNICAL FIELD The present invention relates to a method for preparing metal nanoparticles using a microfluidic reactor,

The present invention relates to a method for preparing metal nanoparticles using a microfluidic reactor, and more particularly, to a droplet-based microfluidic reactor and metal nanoparticles produced thereby.

Microfluidic process technology has been developed over the past decade by various fabrication techniques, and various microfluidic devices have been used. However, when a material is synthesized using a microfluidic device, since the fluid has a very small Reynolds number in a micro-sized channel, the fluid forms a laminar flow, and thus the mixing of materials is not uniform. One good way to solve the heterogeneous mixing problem is to form droplets. Using two fluids that do not mix with each other, a small droplet having a volume ranging from a micrometer to a picoliter is formed, so that the mixing of materials by the advection and diffusion in the droplet is performed quickly, thereby enabling uniform mixing.

Silver nanoparticles (AgNP) have been attracting much interest in the past 20 years because they can be applied to various fields such as catalyst, biosensor, antibacterial technology and clinical treatment. In addition, since the chemical and optical properties of silver nanoparticles, which are the basis of such applications, depend on the size, a synthesis method for silver nanoparticles having a uniform size has been studied. The most common method for synthesizing silver nanoparticles is a chemical reduction method of a silver salt solution using a reducing agent such as NaBH ₄ , citrate, hydrazine, and hydroxylamine hydrochloride. However, when a strong reducing agent such as NaBH ₄ is used, monodisperse small-sized particles can be obtained, but it is difficult to control the formation of larger-sized particles. In the case of using citrate, which is a relatively weak reducing agent, Sized particles can not be obtained. In order to control the size of silver nanoparticles, a two-step reduction process has been attempted. In addition, when the above-mentioned general reducing agent is used, there is a problem that it is harmful to the environment. Therefore, there is a need for research on a technology for producing silver nanoparticles of desired size in an environmentally friendly manner. The branched polyethyleneimine (PEI) contains primary, secondary and tertiary amine groups, and many studies have been conducted focusing on the production of gold nanoparticles. However, little research has been done on the formation of silver nanoparticles.

Therefore, a system capable of producing eco-friendly uniformly sized silver (Ag) nanoparticles when a branched polyethyleneimine (PEI) is used as a reducing agent in the synthesis of silver (Ag) nanoparticles using a droplet-based microfluidic reactor .

KR publication number: 10-2014-0036356

The present inventors have found that silver (Ag) nanoparticles can be produced easily and economically uniformly in a short time when a droplet-based microfluidic reactor is used while searching for silver (Ag) nanoparticles , Thereby completing the present invention.

Accordingly, the present invention seeks to provide a microfluidic reactor comprising a static mixer and a T-shaped contactor.

The present invention also provides metal nanoparticles prepared by the microfluidic reactor.

In order to achieve the above object,

The present invention

Two aqueous solution injecting parts for injecting a metal precursor and a reducing agent, respectively;

An oil injection unit for injecting oil;

A first T-shaped contact connected to the two aqueous solution injection parts;

A static mixer connected to the first T-shaped contact to mix the metal precursor and the reducing agent;

A second T-shaped contact connected to the static mixer and the oil injector to generate droplets;

A metal nanoparticle generating unit connected to the second T-shaped contact unit to generate metal nanoparticles from the droplet; And

And a metal nanoparticle collecting unit for collecting the generated metal nanoparticles.

To provide a microfluidic reactor for producing metal nanoparticles.

The present invention also provides metal nanoparticles prepared by the microfluidic reactor.

Hereinafter, the present invention will be described in detail.

1 is a schematic view of a microfluidic reactor according to Example 1. Fig.

Referring to FIG. 1, the microfluidic reactor of the present invention includes two aqueous solution injection units for injecting a metal precursor and a reducing agent, respectively, and an oil injection unit for injecting oil. A static mixer connected to the static mixer and the oil injector to mix the metal precursor and the reducing agent; and a liquid mixing unit connected to the static mixing unit and the oil injecting unit, And a second T-shaped contact portion for generating an enemy. A metal nanoparticle generating unit connected to the second T-shaped contact unit to generate metal nanoparticles from droplets, and a metal nanoparticle collecting unit for collecting the generated metal nanoparticles.

In other words, the first T-shaped contact portion is connected to the two aqueous solution injection portions, so that the aqueous solution of the metal precursor and the aqueous solution of the reducing agent can be brought into contact with each other. The contacted aqueous solution of the metal precursor and the aqueous solution of the reducing agent maintain a nonuniformly mixed state and form a laminar flow. At this time, the aqueous solution of the metal precursor and the aqueous solution of the reducing agent in the laminar flow state are uniformly mixed in the static mixing portion connected to the first T-shaped contact portion.

 Further, the second T-shaped contact portion is connected to the static mixing portion and the oil injection portion, and the mixed aqueous solution and the oil are contacted to form a droplet. As described above, a large amount of droplets are generated in a short time as the aqueous solution, which is a different liquid, and the oil come in contact through the second T-shaped contact portion.

At this time, the droplets are synthesized at a predetermined temperature in the metal nanoparticle generating unit to produce metal nanoparticles. The resulting metal nanoparticles are centrifuged in the metal nanoparticle collecting unit, and unreacted metal precursor and reducing agent The metal nanoparticles can be obtained.

This droplet-based process is focused on producing unmixed phases unlike the continuous flow system. By using a droplet-based process, each droplet can be independently controlled within a microfluidic reactor to individually move, mix, and analyze.

The metal may be gold (Au), silver (Ag), platinum (Pt) or the like, preferably silver (Ag). The metal precursor may be silver nitrate (AgNO ₃ ), perchloric acid silver (AlClO ₄ ), silver chlorate silver (AgClO ₃ ), silver carbonate silver (Ag ₂ CO ₃ ), silver sulfate silver (Ag ₂ SO ₄ ) (AgBr), fluorine silver (AgF), or the like, and silver nitrate (AgNO ₃ ) is preferable.

The reducing agent is polyethyleneimine, NaBH _4, citrate, hydrazine, hydroxylamine, and the like hydrochloride, and more preferably polyethyleneimine which is a preferred, and branched polyethyleneimine. The polyethyleneimine may be branched polyethylenimine having a molecular weight of 60 kDa or less, but is not limited thereto.

The oil may be an industrial oil including grape seed oil, olive oil, soybean oil, edible oil including canola oil, and silicone oil, hydrocarbon oil, and fluorine oil. The hydrocarbon-based oil may be n-decane, isododecane, isohexadecane, isohexyl neopentanoate, and the like. At this time, by adding a surfactant to the oil, the surface tension of the fine droplets is remarkably lowered and can be prevented from being combined with each other. As the surfactant, Cetyl Dimethicone Copolyol (10 weight%) may be used.

The weight ratio of the metal precursor and the reducing agent may be 1: 0.01 to 1:10, but is not limited thereto. The concentration of the reducing agent aqueous solution may be varied according to the size of the desired metal nanoparticles within the above range. The larger the size of the desired metal nanoparticles, the more the concentration of the polyethyleneimine aqueous solution can be used.

The metal precursor, the reducing agent and the oil may be injected at a flow rate of 20 to 80 μL / min, respectively, and the content of each component in the droplet can be controlled by controlling the flow rate.

In the metal nanoparticle generating section for heating the droplet to 40 to 100 占 폚, the reducing agent (particularly, polyethyleneimine) reduces the metal ion to become a metal atom. The resulting metal atoms aggregate with adjacent metal atoms to form metal nanoparticles. At this time, the polyethyleneimine acts as a surface stabilizer to induce the formation of uniform nanoparticles. Thus, the uniform metal nanoparticles produced are in the form of colloids on the aqueous solution of polyethyleneimine surrounded by polyethylimine.

The average diameter of the metal nanoparticles may be 10 to 30 nm, but is not limited thereto. The size of the metal nanoparticles depends on the concentration of the polyethyleneimine and the metal salt. As the total concentration of polyethyleneimine and metal salts increases, larger diameter nanoparticles are produced. That is, as the concentration of the polyethyleneimine and the metal salt increases, more zero-valent metal atoms are formed through the reduction action of the polyethyleneimine, which is capped with polyethyleneimine and forms larger agglomerates before being stabilized.

In addition, the microfluidic reactor may further include a pump connected to the two aqueous solution injecting units and the oil injecting unit for supplying the aqueous solution and the oil, respectively. The size, shape and amount of the droplets can be adjusted by controlling the flow rate by the pumping speed of the pump device.

The present invention also provides metal nanoparticles prepared by the microfluidic reactor. The metal nanoparticles according to the present invention are manufactured by a microfluidic reactor, so that they can be manufactured easily and economically in a short time, and have the advantage of having a uniform size.

The droplet-based microfluidic reactor according to the present invention can be manufactured in a simple and economical manner by including a static mixer and a T-shaped contactor, and can produce silver (Ag) nanoparticles of a uniform size in an eco- There is an effect.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows droplets in a droplet formation zone and a droplet collection zone formed by (a) a microfluidic reactor and (b) according to Example 1;
2 is a transmission electron microscope (TEM) image of silver nanoparticles (AgNP) according to Example 1, (b) a high resolution transmission electron microscope (HR TEM) image, (c) X-ray diffraction (XRD) (d) UV-vis. Fig.
Figure 3 shows the UV-Vis of silver nanoparticles (AgNP) prepared according to reaction time using (a) microfluidic reactor and (b) batch system. Fig.
Fig. 4 is a graph showing the results of (a) mixing ability images of a static mixer, (b) UV-Vis of silver nanoparticles (AgNP) with and without static mixer. (TEM) image of silver nanoparticles (AgNP) when a static mixer is used, and (d) a static mixer is not used. Here, the mixing effect was confirmed using red and blue dyes.
Figure 5 shows the results of (a) UV-Vis of silver nanoparticles (AgNP) according to five different weight ratios of silver nitrate (AgNO ₃ ) and branched polyethyleneimine (BPEI). (B) 30:10, (c) 25:15, (d) 20:20, (e) 15:25, and (f) 10:30, respectively, of silver (AgNO ₃ ) and BPEI (TEM) image of silver nanoparticles (AgNP) in the case of a silver nanoparticle.

Hereinafter, preferred embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the following examples are provided only for the purpose of easier understanding of the present invention, and the present invention is not limited by the examples.

Example  1. Silver nanoparticles using a microfluidic reactor AgNP )

First, the branched polyethyleneimine (BPEI, MW = 750,000) and silver nitrate (AgNO ₃₎ the sigma-was purchased from Aldrich (USA), dissolved in deionized water was prepared for each concentration of aqueous solution of 0.0338 g mL ^-1, This was reacted in a microfluidic reactor.

Specifically, each of the branched polyethyleneimine and silver nitrate aqueous solutions was filled in a syringe (NORM-JECT® Plastic Syringe, 5 mL, Restek, USA), and a microtube (DuPont® FEP Fluoropolymer Tubing, 1/16 " OD (0.030 "ID, IDEX, USA) was filled with oil phase n-decane (Daejung, Korea) to form droplets. Then, after it attached to the branched polyethyleneimine, and not each other syringe pump if another syringe filled with each syringe and n- decanoic filled with silver nitrate aqueous solution, the respective solution and the flow rate of n- decane five days 40, 60 uL min ^{- 1} and injected into a microreactor. Thereafter, droplet formation and synthesis reaction of silver nanoparticles (AgNP) were performed in the microreactor, and the microtube was maintained at 60 DEG C using a water circulator.

Also, a mixed aqueous solution was prepared by mixing an aqueous solution of branched polyethyleneimine and an aqueous solution of silver nitrate in the first T-junction in the microreactor, and the mixed aqueous solution and the n-decane oil were mixed in a second T-shaped adapter to form droplets . At this time, a static mixer was used for uniform mixing of the polyethyleneimine aqueous solution and the silver nitrate aqueous solution. In addition, the synthesis reaction of silver nanoparticles (AgNP) was carried out from droplets in a 293 cm long microtubes connected to a second T-type adapter. The product from the microtube was then placed in a 50 mL cylindrical tube filled with isopropanol (IPA), centrifuged twice at 10,000 rpm for 80 minutes, and the silver nitrate and branched polyethyleneimine remaining in the supernatant was removed to obtain silver nanoparticles AgNP).

The droplets in the droplet formation zone and the droplet collection zone formed by (a) the microfluid reactor and (b) according to Example 1 are shown in Fig.

Experimental Example  1. Silver nanoparticles ( AgNP ) Morphology, crystallographic and optical characterization

The morphology, crystallographic and optical properties of silver nanoparticles (AgNP) according to Example 1 were analyzed. The morphology of silver nanoparticles (AgNP) was analyzed by transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HR TEM), and X-ray diffraction (XRD) was analyzed at 35 kV and 35 mA using a D / Max-2500 diffractometer. Respectively. In addition, the optical characteristics in the visible light region were analyzed using a V-770 UV-Visible / NIR spectroscope (Jasco, Japan). The yield was analyzed by performing thermogravimetric analysis in a nitrogen atmosphere by heating from room temperature to 800 DEG C at 10 DEG C / min.

(A) transmission electron microscope (TEM) image of silver nanoparticles (AgNP) according to Example 1, (b) high resolution transmission electron microscope (HR TEM) image, (c) X-ray diffraction ) UV-Vis. The spectrum is shown in Fig.

As shown in FIGS. 2 (a) and 2 (b), the silver nanoparticles (AgNP) exhibited a pseudo-spherical shape and showed a diameter of 10 to 30 nm. Also, silver nanoparticles (AgNP) appeared to be single or paired.

As shown in FIG. 2 (c), silver nanoparticles (AgNP) exhibited diffraction peaks at 38.3 °, 44.4 °, 64.6 ° and 77.7 °, which corresponded to (111), (200) Face-centered cubic of the (220) and (311) planes.

As shown in Fig. 2 (d), UV-Vib. The maximum peak position of the spectrum was at a wavelength of about 430 nm. The maximum peak was found to be larger and red-shifted with spherical particles, and the maximum peak was blue-shifted until 60 minutes and then red-shifted after 60 minutes. This is because silver nanoparticles (AgNP) are formed by the silver (Ag) precursor until 60 minutes, and then the silver nanoparticles (AgNP) are aggregated with each other.

Comparative Experimental Example  1. Comparison of production times of microfluidic reactors and batch systems

The production times of silver nanoparticles (AgNP) in microfluidic reactors and batch systems were compared.

UV-Vis of silver nanoparticles (AgNP) prepared according to reaction time using (a) a microfluidic reactor, and (b) a batch system. The spectrum is shown in Fig.

As shown in FIG. 3, when using a microfluidic reactor and a batch system (bulk scale), silver nanoparticles (AgNP) showed a large difference in production time. It took about 10 hours to produce silver nanoparticles using a branched-type polyethyleneimine (BPEI) in bulk scale, but silver nanoparticles were synthesized in a microfluidic reactor only in 60 minutes. This is because the heat transfer characteristic of the microfluidic reactor is very good, and when the microfluidic reactor is used, the reaction time can be shortened as compared with the bulk reactor.

From the above results, it was confirmed that when the silver nanoparticles (AgNP) were prepared using the microfluidic system according to the present invention, silver nanoparticles of uniform size could be produced in a very short time.

Experimental Example  2. Silver nanoparticles with and without static mixer ( AgNP )

The silver nanoparticles (AgNP) prepared using the static mixer according to Example 1 were compared with those prepared using silver nanoparticles (AgNP) without the static mixer.

(a) Mixing capacity image of static mixer, (b) UV-Vis of silver nanoparticles (AgNP) with and without static mixer. (TEM) images of the silver nanoparticles (AgNP) without the use of static mixers and (c) static mixers and (d) static mixers are shown in FIG. Here, the mixing effect was confirmed using red and blue dyes.

As shown in FIG. 4 (a), the aqueous solution of silver nitrate and polyethyleneimine having a branched structure formed red and blue laminar flows respectively before passing through a static mixer, and then they were uniformly mixed after passing through a static mixer to form a purple solution.

As shown in Fig. 4 (b), UV-Vis of silver nanoparticles (AgNP) according to the presence or absence of static mixer. As a result of the spectral measurement, the peak of the UV-Vib spectrum showed a sharpness when using a static mixer, but a bulk peak when the static mixer was not used.

In addition, as shown in the transmission electron microscope (TEM) images of FIGS. 4 (c) and 4 (d), silver nanoparticles (AgNP) exhibited a uniform size when using a static mixer, Unless otherwise, it showed uneven size.

From the above results, it can be seen that silver nanoparticles (AgNP) having a uniform size are formed by inducing uniform mixing of silver nitrate and branched polyethyleneimine when a static mixer is used.

Experimental Example  3. Silver nitrate and Branches  It was found that silver nanoparticles AgNP )

The morphology and optical properties of silver nanoparticles (AgNP) according to their mixing ratios were analyzed by controlling the flow rate of aqueous solution of silver nitrate (AgNO ₃ ) and aqueous solution of branched polyethyleneimine (BPEI).

(a) UV-Vis of silver nanoparticles (AgNP) according to five different weight ratios of silver nitrate (AgNO ₃ ) and branched polyethylenimine (BPEI). Spectrum, and AgNO ₃ (AgNP) when the weight ratio of BPEI and BPEI is 30:10, (c) 25:15, (d) 20:20, (e) 15:25, and (f) A transmission electron microscope (TEM) image is shown in Fig.

As shown in Figure 5, when the weight of the branched polyethyleneimine (BPEI) is higher than the weight of silver nitrate _{(AgNO 3) (e, f} ) of uniform size are the production of nanoparticles (AgNP) eoryeowoona, branched polyethylene Silver nanoparticles (AgNP) of uniform size were prepared when the weight of imine (BPEI) was lower than that of silver nitrate (AgNO ₃ ) or (a, b) or (c) Is produced.

From the above results, it was confirmed that silver nanoparticles of different sizes can be produced by controlling the flow rate ratio of aqueous solution of silver nitrate (AgNO ₃ ) and aqueous solution of branched polyethyleneimine (BPEI).

Claims (12)

A metal precursor aqueous solution injection unit; A reducing agent aqueous solution injecting part; Oil injection part; A first T-shaped contact; A second T-shaped contact; A metal nanoparticle generating portion and a metal nanoparticle collecting portion,
The metal precursor aqueous solution injection unit; A reducing agent aqueous solution injecting part; And the oil injection portion are respectively connected to the aqueous solution of the metal precursor, the aqueous solution of the reducing agent and the microtube for transferring the oil,
The metal precursor aqueous solution injection unit; A reducing agent aqueous solution injecting part; And the oil injecting part respectively discharge the metal precursor aqueous solution, the reducing agent aqueous solution and the oil at a flow rate of 20 to 80 uL / min (min)
The first end of the first T-shaped contact portion is connected to the end of the microtube connected to the metal precursor aqueous solution injecting portion, and the other end of the first T-shaped contact portion opposite to the one end of the first T- Connected to the distal end of the tube,
The center-side end of the first T-shaped contact portion and the center-side end of the second T-shaped contact portion are connected to each other by a microtube for moving a fluid. The microtube includes a metal precursor aqueous solution flowing in the metal precursor aqueous solution injection portion, And a static mixer for mixing the reducing agent aqueous solution introduced from the reducing agent aqueous solution injecting unit,
One end of the second T-shaped contact portion is connected to an end of the microtube connected to the oil injection portion,
The second T-shaped contact portion contacts the mixture of the aqueous solution of the metal precursor and the aqueous solution of the reducing agent introduced from the direction of the first T-shaped contact portion with the oil introduced from the direction of the oil injection portion at the center of the inner portion and discharges it into the metal nano- ,
Wherein the metal nanoparticle generating unit comprises a microtube for producing metal nanoparticles having a particle size of 2 to 18 nm and a standard deviation of an average size of +/- 2 nm or less from the droplet, Microfluidic reactor for the production of metal nanoparticles. The method according to claim 1,
Wherein the metal is gold (Au), silver (Ag), or platinum (Pt). The method according to claim 1,
The metal precursor may be silver nitrate (AgNO ₃ ), perchloric acid silver (AgClO ₄ ), chlorate silver (AgClO ₃ ), silver carbonate (Ag ₂ CO ₃ ), silver sulfate (Ag ₂ SO ₄ ), silver chloride ) And at least one silver precursor selected from the group consisting of fluorine silver (AgF). The method according to claim 1,
The reducing agent, the microfluidic reactor, characterized in that at least one member selected from the group consisting of polyethyleneimine, NaBH _4, citrate, hydrazine and hydroxylamine hydrochloride. The method according to claim 1,
Wherein the oil is at least one selected from the group consisting of grape seed oil, olive oil, soybean oil, edible oil including canola oil, and industrial oil including silicone oil, hydrocarbon oil and fluorinated oil. The method according to claim 1,
Wherein the weight ratio of the metal precursor and the reducing agent is 1: 0.01 to 1:10. delete The method according to claim 1,
Wherein the metal nanoparticle generating portion is maintained at 40 to 100 < 0 > C. delete The method according to claim 1,
Wherein the metal precursor aqueous solution injecting portion, the reducing agent aqueous solution injecting portion, and the oil injecting portion are respectively connected to a metal precursor aqueous solution, a reducing agent aqueous solution, and a pump for supplying oil. delete The metal precursor aqueous solution is injected into the metal precursor aqueous solution injecting portion and then transferred to one end of the first T-shaped contact portion through the microtube connected to the metal precursor aqueous solution injection portion at a flow rate of 20 to 80 uL / min (min) Is injected into the reducing agent aqueous solution injecting part and then transferred to the other end opposite to the one end side of the first T-shaped contact part through the microtube connected to the reducing agent aqueous solution injecting part at a flow rate of 20 to 80 uL / min (min) The weight ratio of the metal precursor to the reducing agent to be contacted is 1: 0.01 to 1:10,
The contacted metal precursor aqueous solution and the reducing agent aqueous solution are transferred to the center side end of the first T-shaped contact portion while being formed into a laminar flow in a nonuniformly mixed state,
The laminar flow of the metal precursor aqueous solution and the reducing agent aqueous solution in the non-uniform mixed state is transferred to the static mixing portion through the microtubes connected to the center side end of the first T-
The metal precursor aqueous solution and the reducing agent aqueous solution are uniformly mixed in the static mixing portion and then transferred to the center side end of the second T-shaped contact portion through the microtube connected to the static mixing portion,
The oil is injected through the oil injection part at a flow rate of 20 to 80 uL / min., And the injected oil flows into one end of the second T-shaped contact part through the microtube connected to the oil injection part,
A uniform mixture of the aqueous solution of the metal precursor and the aqueous solution of the reducing agent introduced from the center side end of the second T-shaped contact portion at the center of the second T-shaped contact portion is contacted with the oil introduced from one end of the second T- Discharging a uniform mixture of the aqueous solution of the metal precursor and the aqueous solution of the reducing agent and the oil in the form of droplets to the other end opposite to the one end of the contact portion,
The other end of the second T-shaped contact portion is connected to a metal nanoparticle generating portion made of a microtube, and the droplet is transferred to the metal nanoparticle generating portion,
Wherein the metal nanoparticle generating unit generates metal nanoparticles having a uniform size of 2 to 18 nm in particle size and a standard deviation of ± 2 nm or less from the droplet, ≪ / RTI >

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