KR20060009560A - Nanoparticle Charging Method - Google Patents

Abstract

The present invention relates to a method of charging the nanoparticles at high cost regardless of the method of obtaining and size, and the nanoparticles are mixed with the vaporized solvent, the reaction temperature is lowered to condense the solvent on the surface of the nanoparticles, the solvent is condensed According to the method of the present invention by charging the charged nanoparticles and then evaporating the solvent, it is possible to obtain expensive charged nanoparticles without losing charge while maintaining the original particle size.

Description

Charging method of nanoparticles {METHOD FOR CHARGING OF NANOPARTICLE}             

1 is a schematic diagram showing a conventional positive electrode charging method using a radioactive element,

2 is a schematic diagram showing a conventional charging method using soft X -rays,

3 is a schematic diagram showing a conventional charging method using a corona discharge,

4 is a schematic diagram showing a charging process of the nanoparticles according to the present invention,

Figure 5 is a schematic diagram showing a mixing-type particle magnifier used in the present invention,

6 is a schematic diagram of a system for charging nanoparticles and for checking charged values of charged nanoparticles in accordance with the present invention;

7A and 7B are graphs showing changes in the electrical mobility distribution and particle size distribution of nanoparticles charged at high cost according to the present invention, respectively.

<Explanation of symbols for the main parts of the drawings>

10: transfer gas (nitrogen) 20: flow meter

30: mixed particle size increaser 40: scan type particle size distribution measuring instrument

50: corona charger 60: heater

70: transfer gas 80: nano fine type electrostatic classifier

90: condensation nucleus counter 100: Faraday cup charge meter

The present invention relates to a method for charging nanoparticles, and more particularly, to a method for charging a nanoparticle at an expensive regardless of size by undergoing a condensation and evaporation process of a solvent on the surface of the nanoparticle.

Recently, many attempts have been made to pattern-deposit metal nanoparticles to nanometer size for the manufacture of positron devices, next-generation optoelectronic devices, etc. In this process, charging of nanoparticles is very important in attaching particles to desired positions. In particular, there is an increasing demand for expensively charged nanoparticles.

Charging of the aerosol nanoparticles used to control the particles during formation, deposition, or measurement of the nanoparticles is mainly performed through interaction with surrounding ions, and can be classified into positive and negative pole charges depending on the polarity of the ions. In addition, a charging method using a radioactive material, ultraviolet or soft X -rays, corona discharge, or the like is mainly used.

For example, in the positive electrode charging method using radioactive elements (Am-241, Kr-85, Po-210, etc.) shown in FIG. 1, the aerosol particles are ionized while passing around the radioactive element, and about 10% of the particles are positively charged. Will be. However, this method has a disadvantage in that it is difficult to charge more than ± 2 in the case of nanoparticles having a size of 50 nm or less.

On the other hand, in the case of the charging method using the soft X -ray shown in FIG. 2, the aerosol particles are charged in a high concentration of ionic atmosphere to reach the particles in the bipolar equilibrium state for a shorter time than in the case of using the radioactive element. Although there is an advantage that ± 1 can increase the charging rate, it is also difficult to obtain expensively charged nanoparticles.

In addition, in the corona discharge method shown in FIG. 3, when a DC high voltage is applied to the center wire and grounded to a plate having a hole, a corona discharge occurs and a high concentration of monopolar ions is generated to charge particles to a single pole, thereby forming a sufficient ion atmosphere. This makes it possible to charge the particles more efficiently than when using radioactive elements. However, in the case of nanoparticles of 50 nm or less, it is also difficult to charge more than ± 2.

In the conventional charging methods as described above, it is impossible to obtain expensively charged nanoparticles because the charging rate decreases rapidly as the size decreases.

Accordingly, it is an object of the present invention to provide a method that can easily charge the nanoparticles regardless of the particle size and expensive.

In order to achieve the above object, in the present invention, the nanoparticles are mixed with a vaporized solvent, the reaction temperature is lowered to condense the solvent on the surface of the nanoparticles, the solvent is charged with the nanoparticles condensed, and then the solvent is evaporated. It provides a method of charging the nanoparticles, including.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

The nanoparticle charging method according to the present invention is characterized by removing the condensed solvent by evaporation after charging the nanoparticles in a state where the solvent is condensed on the surface in order to solve the problems of the conventional nanoparticle charging methods.

The charging process of the nanoparticles according to the present invention is schematically illustrated in FIG. 4, specifically, (1) mixing nanoparticles of various states with a vaporized solvent; (2) lowering the reaction temperature to condense the solvent on the nanoparticle surface; (3) charging the nanoparticles with the solvent condensed on the surface; (4) evaporating and removing the solvent condensed on the surface of the nanoparticles.

In the present invention, nanoparticles can be used regardless of the method of obtaining and the size.

In the present invention, as the solvent, an alcohol compound having good condensation efficiency, which is advantageous for the growth of particles, and which is easy to evaporate and harmless to human body can be used. For example, ethylene glycol having good particle growth efficiency when evaporated at about 120 ° C. and condensed at 40 ° C., butanol having good particle growth efficiency when evaporated at about 35 ° C. and condensed at 10 ° C. may be preferably used.

According to the present invention, the solvent is vaporized in the heating section of the mixed particle diameter enhancer shown in FIG. 5, for example, and then moved by a conveying gas such as nitrogen and mixed with the nanoparticles. At this time, the vaporization temperature of the solvent may vary depending on the chemical properties of the solvent.

Next, the mixture of the nanoparticles and the vaporized solvent passes through the condenser of the intensifier, and when the temperature of the condenser is lowered, the vaporized solvent condenses on the surface of the nanoparticles. At this time, the condensation temperature of the solvent may vary depending on the chemical properties of the solvent.

Nanoparticles in a state where the solvent is condensed on the surface may be charged through a conventional charger, such as a corona charger, a cathode charger using radiation, a soft X-ray charger, and the like. At this time, the particles surrounded by the condensed solvent are charged more expensively than the charging in the original particle size state due to the increase in the total size.

When the charged particles are dried using a heating means such as a heater, the solvent condensed on the surface of the nanoparticles is evaporated, and the nanoparticles are restored to their original nanometer size while being charged at high cost without loss of charge. Can be maintained.

As such, according to the present invention, even nanoparticles having a very small size can be easily charged at a high cost using various conventional charging methods.

Hereinafter, the present invention will be described in more detail based on the following examples. However, the following examples are not intended to limit the invention only.

Example 1

The charging process of the nanoparticles according to the present invention can be performed using the system shown in FIG. First, the mixed type for contacting the solvent with the monodisperse spherical gold nanoparticles measured at about 27 nm through a scan type electrostatic particle size meter 40 at a flow rate of 1.5 slm (standard liter per minute; l / min) Introduced into the mixing section of the particle size increaser (30). On the other hand, ethylene glycol was vaporized by heating to 120 ° C. in the heating section of the expander 30, and then moved to the mixing section using 0.352 slm nitrogen gas introduced through the flowmeter 20. The mixture of nanoparticles and ethylene glycol was moved to the condensation unit of the intensifier 30 by nitrogen gas, at which time the temperature of the condensation unit was lowered to 40 ° C. to condense ethylene glycol. The nanoparticles containing the condensed ethylene glycol were passed through a corona charger 50 and passed through a heater 60 to evaporate ethylene glycol. Nano differential mobility analyzer (80) and Faradaycup elecrometer using nitrogen gas (70) to measure the electrophoretic mobility of nanoparticles in evaporated solvent. Passed through (100) was discharged, the evaporated solvent was discharged by condensing again in the condensation nucleus counter (90). Next, the size of the discharged nanoparticles was again measured by the scan type particle size distribution analyzer 40.

Comparative Example 1

The same process as in Example 1 was performed except that the monodispersed spherical nanoparticles measured at 27 nm were charged directly with a corona charger without passing through the mixed particle diameter enhancer.

 The mobility of the nanoparticles treated according to Example 1 and Comparative Example 1 is shown in FIG. 7A, and as a result, the electrical mobility of the nanoparticles charged according to Example 1 of the present invention is 0.118 cm 2 / Vs. , Compared with Comparative Example 1 (0.002 cm 2 / Vs) can be seen that about 60 times increased. That is, it can be seen that the nanoparticles charged according to the present invention are charged at a considerably expensive price from those having a large degree of electrophoretic mobility.

On the other hand, the particle size after the treatment according to Example 1 is shown in Figure 7b, the results show that the size distribution of the nanoparticles subjected to the charging process according to the present invention is kept constant as the original particle size distribution Can be.

According to the charging method according to the present invention, expensive charging is possible by overcoming the limitation of monovalent charging even for nanoparticles having a very small particle size, and the expensively charged nanoparticles are easily reacted to an appropriate electrical force. It can be controlled and usefully used in the manufacture of positron devices, next-generation optoelectronic devices, and the like.

Claims (4)

Mixing the nanoparticles with the vaporized solvent, lowering the reaction temperature to condense the solvent on the surface of the nanoparticle, charging the nanoparticles on which the solvent is condensed, and then evaporating the solvent. The charging method according to claim 1, wherein the solvent is an alcohol compound. The charging method according to claim 2, wherein the solvent is ethylene glycol or butanol. The charging method of claim 1, wherein the charging method is performed in an apparatus including a mixing-type particle magnifier.

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