JP2009082828A - Reverse micelle solution, inorganic nanoparticles, and method for producing inorganic nanoparticles - Google Patents

Abstract

Provided are a reverse micelle solution that is stable for a long period of time, monodisperse inorganic nanoparticles that are produced using a reverse micelle solution having such characteristics, and that have little variation in particle size and composition between particles, and a method for producing the same. To do.
The reverse micelle solution of the present invention comprises water, a hydrophobic organic solvent, a surfactant, and a hydrophilic organic solvent having a solubility parameter difference of 0 to 5 based on the hydrophobic organic solvent. Or water, a hydrophobic organic solvent, a surfactant, and a hydrophilic organic solvent having a difference in inorganic value / organic value ratio within ± 1.5 based on the surfactant The hydrophilic organic solvent contains 2 to 300 mmol per liter of the total volume. Inorganic nanoparticles can be obtained by a production method using these reverse micelle solutions.
[Selection figure] None

Description

  The present invention relates to a reverse micelle solution, inorganic nanoparticles, and a method for producing inorganic nanoparticles.

A generally well-known micelle is a normal micelle in which oil is dispersed as oil droplets in an aqueous phase using a surfactant. On the other hand, a state in which water is dispersed as water droplets in the oil phase using a surfactant is called reverse micelle.
The reverse micelle method is a method for obtaining inorganic nanoparticles by causing a reduction reaction, an oxidation reaction sol-gel reaction, an exchange reaction, or the like in small water droplets confined in an oil phase.

  In recent years, inorganic nanoparticles are being used in various fields and are considered promising. For example, organic inorganic nanocomposite films, catalyst films, electromagnetic shielding films, dielectric films, functional film materials such as antibacterial and bactericidal sheets, single-electron tunnel devices, optical switches, ultrahigh-density magnetic recording media, and other nanodevices, biotechnology Sensors, contrast agents, medical materials such as DDS, sensor materials such as infrared sensors, gas sensors, and humidity sensors, nanowiring materials, liquid crystal materials, and paint materials.

The reverse micelle method has been studied for a long time, and there are many known reduction reactions, oxidation reactions, sol-gel reactions and exchange reactions, and many research papers have been published. In addition, it is also known to add a hydrophilic organic solvent in order to allow reverse micelles to exist stably, and is described in Non-Patent Documents 1 to 4, for example.
However, in Non-Patent Documents 1 to 4, alcohol is used as the hydrophilic organic solvent, (the amount of added hydrophilic organic solvent mol) / (volume of water used for reverse micelle formation + hydrophobic organic used for reverse micelle formation). In the case of calculation based on the calculation of (volume of solvent + volume of hydrophilic organic solvent), inorganic particles in reverse micelles are produced using an addition amount of 500 mmol / l or more.
However, in the case of the addition amount as in Non-Patent Documents 1 to 4, the reverse micelle solution becomes an unstable region, and it is difficult to reduce the particle size variation of the inorganic particles and the composition variation between the particles.

Han, X .; Liu, H .; Hu, Y., Colloids and Surfaces A: Physicochem. Eng. Aspects. 273, 179-183 (2006) Sato, H .; Ohtsu, T .; Komasawa, I., J. Collid Interface Sci. 230, 200-204 (2000) Weihua, W .; Xuelin, T .; Kai, C .; Gengyu, C., Colloids and Surfaces A: Physicochem. Eng. Aspects. 273, 35-42 (2006) Carpenter, E. E .; Sims, J. A .; Wienmann, J. A .; Zhou, W. L .; O'Connor, C. J., J. Appl. Phys. 87 (9), 5615-5617 (2000).

An object of the present invention is to provide a reverse micelle solution that is not achieved in the prior art and is stable for a long period of time.
Another object of the present invention is to provide monodisperse inorganic nanoparticles that are produced using a reverse micelle solution having such characteristics and that have little variation in particle size and composition between particles, and a method for producing the same.

As a result of intensive studies, it has been found that the present invention shown below can be solved.
<1> Water, a hydrophobic organic solvent, a surfactant, and a hydrophilic organic solvent having a solubility parameter difference of 0 to 5 based on the hydrophobic organic solvent, wherein the hydrophilic organic solvent is Reverse micelle solution with 2 to 300 mmol per liter of total volume.
<2> water, a hydrophobic organic solvent, a surfactant, and a hydrophilic organic solvent having a difference in inorganic value / organic value ratio within ± 1.5 based on the surfactant The reverse micelle solution in which the hydrophilic organic solvent is 2 to 300 mmol per liter of the total volume.

<3> The reverse micelle solution according to <1> or <2>, wherein the surfactant is contained in an amount of 50 mmol to 500 mmol with respect to 1 liter of the hydrophobic organic solvent.
<4> The reverse micelle solution according to <1> to <3>, wherein the water is 1 mol to 300 mol with respect to 1 mol of the surfactant.
<5> An inorganic nanoparticle produced using the reverse micelle solution according to any one of <1> to <4>.
<6> A method for producing inorganic nanoparticles, comprising using the reverse micelle solution according to any one of <1> to <4>.

  According to the present invention, it is possible to provide a reverse micelle solution that is stable for a long period of time. In addition, it is possible to provide monodisperse inorganic nanoparticles that are produced using a reverse micelle solution having such characteristics and that have little variation in particle size and composition between particles, and a method for producing the same.

Hereinafter, the reverse micelle solution of the present invention will be described in detail.
The description of the constituent elements described below is based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the present invention, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

The reverse micelle solution of the present invention comprises water, a hydrophobic organic solvent, a surfactant, and a hydrophilic organic solvent having a solubility parameter difference of 0 to 5 based on the hydrophobic organic solvent, and the hydrophilic The organic solvent is 2 millimoles to 300 millimoles per liter total volume.
Another reverse micelle solution of the present invention has a difference in the inorganic value / organic value ratio within ± 1.5 based on water, a hydrophobic organic solvent, a surfactant, and the surfactant. A hydrophilic organic solvent, and the hydrophilic organic solvent is 2 to 300 mmol per liter of the total volume.

As is well known, the solubility parameter of a hydrophilic organic solvent is a value that is defined based on the regular solution theory introduced by Hildebrand, and is a measure for expressing the intermolecular force. The regular solution theory assumes that the force acting between the solvent and the solute is only an intermolecular force. The actual solution is not necessarily a regular solution, but is more easily dissolved (the compatibility is higher) as the difference in solubility parameter between the solvent and the solute (or the solvent and the solvent) is smaller. The solubility parameter is also expressed as δ, SP value, solubility parameter, and Hildebrand parameter, and can be calculated if the molar heat of vaporization (ΔH: cal / mol) and the molar volume (V: cm ³ / mol) are known.

  The inorganic value / organic value ratio in a compound can be obtained by determining the ratio based on the inorganic value and organic value of elements, functional groups, etc. of the compound. For example, carbon has an inorganic value = 0 and an organic value = 20, and the ratio of the inorganic value / organic value of alkanes is 0. The OH group has an inorganic value = 100 and an organic value = 0, and methanol has 100/20 = 5.

  As the hydrophilic organic solvent in the reverse micelle solution of the present invention, those having a solubility parameter difference of 0 to 5 based on the hydrophobic organic solvent are used. More preferably, it is 0-4, Most preferably, it is 0-3. If the difference in solubility parameter is 0 to 5, the reverse micelle solution can be stably present.

  Further, as the hydrophilic organic solvent in the reverse micelle solution of the present invention, those having a difference of the inorganic value / organic value ratio within ± 1.5 based on the surfactant are used. More preferably, it is within ± 1, and most preferably within ± 0.5. If the difference between the inorganic value / organic value ratio is within ± 1.5, the reverse micelle solution can be stably present.

  The hydrophilic organic solvent that can be used in the present invention needs to satisfy the above-mentioned conditions for the hydrophobic organic solvent and the surfactant described later. It is necessary to select according to the hydrophobic organic solvent and surfactant to be used. As the hydrophilic organic solvent, 1-propanol (solubility parameter: 11.1, inorganic value / organic value ratio: 1.7) , Isopropanol (solubility parameter: 11.5, inorganic value / organic value ratio: 2.0), 1-butanol (solubility parameter: 10.5, inorganic value / organic value ratio: 1.3), 1 -Hexanol (solubility parameter: 9.6, inorganic value / organic value ratio: 0.8), 1-octanol (solubility parameter: 8.7, inorganic value / organic value ratio: 0.6), benzyl Alcohol (solubility parameter: 10.9, inorganic value / organic value ratio: 0.8), cyclohexanol (solubility parameter: 9.8, inorganic value / organic value ratio: 0.9), etc. Can, but limited to these It is not.

  The amount of the hydrophilic organic solvent in the reverse micelle solution of the present invention is 2 to 300 mmol and 20 to 100 mmol per liter of the total volume of the reverse micelle solution from the viewpoint of the stability of the reverse micelle solution. Is preferred.

  The hydrophobic organic solvent that can be used in the present invention may be any one that can dissolve the surfactant and satisfy the above-mentioned conditions for the hydrophilic organic solvent. Alkanes and ethers are preferred. The alkane is preferably an alkane having 7 to 12 carbon atoms. Specific examples include heptane (solubility parameter: 6.9), octane (solubility parameter: 6.9), nonane, decane (solubility parameter: 7.0), undecane, and dodecane. On the other hand, examples of ether include diethyl ether (solubility parameter: 7.3), dipropyl ether, and dibutyl ether.

  The amount of the hydrophobic organic solvent in the reverse micelle solution of the present invention is a criterion for determining the total volume to be produced, and may be arbitrarily determined. This determines the amount of the others.

As an example of the surfactant in the present invention, an oil-soluble surfactant is used, and a sulfonate type, for example, aerosol OT (manufactured by Wako Pure Chemical Industries, Ltd., inorganic value / organic value ratio: 0.9). Quaternary ammonium salt type, for example, cetyltrimethylammonium bromide (inorganic value / organic value ratio: 1.1), ether type, for example, pentaethylene glycol dodecyl ether (inorganic value / organic value ratio: 0.9) However, it is not limited to these.
Of these surfactants, aerosol OT is preferred from the viewpoint of solubility.

  The amount of the surfactant with respect to the hydrophobic organic solvent in the present invention may vary depending on the solubility of the surfactant, but is preferably 50 mmol to 500 mmol with respect to 1 liter of the hydrophobic organic solvent.

  The amount of water in the reverse micelle solution in the present invention is preferably 1 mol to 300 mol, and more preferably 1 mol to 100 mol, relative to 1 mol of the surfactant.

The reverse micelle solution of the present invention is preferably used for producing inorganic nanoparticles. The inorganic nanoparticles that can be prepared using the reverse micelle solution of the present invention include metal, alloy, or oxide inorganic nanoparticles. Examples of inorganic nanoparticles include metals and metal compounds such as Ag, Au, Pt, Pd, Cu, Co, and Fe, or alloys or mixtures containing two or more of these elements, TiO ₂ , ZnO, Fe ₃ O ₄ , InSnOx. Examples of the oxide include, but are not limited to.
In order to produce inorganic nanoparticles using the reverse micelle solution of the present invention, the reverse micelle solution contains inorganic nanoparticles in addition to the above hydrophobic organic solvent, surfactant, hydrophilic organic solvent and water. A metal compound for is included.
In the present invention, as a metal compound used as a raw material for obtaining a metal, an alloy or an oxide, many kinds of commercially available compounds can be used.
Below, the manufacturing method of an inorganic nanoparticle is demonstrated.

  The inorganic nanoparticles in the present invention are prepared by mixing and reacting a reverse micelle solution (I) containing one or more metal compounds and a reverse micelle solution (II) containing a reactive agent such as a reducing agent, an oxidizing agent or a nitriding agent. Can be manufactured. If necessary, inorganic nanoparticles can be produced by raising the temperature after the reaction and aging.

  The metal compound contained in the aqueous solution of the metal compound includes nitrate, sulfate, hydrochloride, acetate, hydrogen acid of a metal complex having a chloride ion as a ligand, and potassium of a metal complex having a chloride ion as a ligand. Examples include salts, sodium salts of metal complexes having chloride ions as ligands, and ammonium salts of metal complexes having oxalate ions as ligands, and these can be arbitrarily selected and used in the production method of the present invention. can do.

  The concentration of the metal compound in each metal compound aqueous solution is preferably 0.1 μmol to 5000 μmol / ml, and more preferably 1 μmol to 2000 μmol / ml.

The reducing agent aqueous solution used in the present invention is composed of, for example, a borohydride compound, ascorbic acid, alcohols, polyols, formalin, hydrazine, H ₂ and water, and these reducing agents are used alone or in combination of two or more. It is preferable to do.
The amount of the reducing agent in the aqueous solution is preferably 3 to 50 mol with respect to 1 mol of the metal compound.

Examples of the oxidizing agent aqueous solution used in the present invention include oxo acid salts (nitrite, chlorate, hypochlorite, iodate, bromate, chromate, permanganate, vanadate, bismuth acid. Salt), peroxide (H ₂ O ₂ , Na ₂ O ₂ , BaO ₂ , H ₂ SO ₅ etc.), Br ₂ , I ₂ etc. and water, and these oxidizing agents are used alone or in combination of two or more. It is preferable to use together.
The amount of the oxidizing agent in the aqueous solution is preferably 3 to 50 mol with respect to 1 mol of the metal compound.

The other reactant aqueous solution used in the present invention comprises, for example, carbonate, borate, sulfide and water, and these reactants are preferably used alone or in combination of two or more.
The amount of the reactant in the aqueous solution is preferably 3 to 50 mol with respect to 1 mol of the metal compound.

  The ratio of water and surfactant in the reverse micelle solutions (I) and (II) may be the same or different, but is preferably the same in order to make the system uniform.

The reverse micelle solutions (I) and (II) prepared as described above are mixed.
The mixing method is not particularly limited, but it is preferable to add and mix the reverse micelle solution (II) while stirring the reverse micelle solution (I) in consideration of the reduction uniformity. The reaction is allowed to proceed after completion of the mixing, and the temperature at that time is set to a constant temperature in the range of -5 to 30 ° C. If the temperature is −5 ° C. or higher, the reaction can be made uniform without condensation of the aqueous phase, and if it is 30 ° C. or lower, aggregation or precipitation hardly occurs and the system can be stabilized. . A preferable temperature is 0 to 25 ° C, and more preferably 5 to 25 ° C.
Here, the “constant temperature” means that the temperature is in a range of T ± 3 ° C. when the set temperature is T (° C.). Even in this case, the upper and lower limits of T are in the above temperature range (-5 to 30 ° C).

  The reaction time needs to be appropriately set depending on the amounts of the reverse micelle solutions (I) and (II), but is preferably 1 to 30 minutes, and more preferably 5 to 20 minutes.

  In the present invention, it is possible to add the same or different reverse micelle solution during the reaction. As the reverse micelle solution, a reverse micelle solution such as a metal compound, a reducing agent, an oxidizing agent or a nitriding agent can be added. Moreover, you may add the acid or alkali for adjusting pH.

Since the reaction greatly affects the monodispersity of the particle size distribution of the obtained inorganic particles, it is preferable to carry out the reaction while stirring as fast as possible.
As the stirring device in the present invention, various commercially available devices can be used. Either a shearing force or no shearing force may be used, but it is preferable that there is no shearing force.

  After the reaction of the reverse micelle solutions (I) and (II), at least one dispersant is preferably added in an amount of 0.001 to 10 moles per mole of inorganic nanoparticles to be produced. If the addition amount of a dispersing agent is 0.001-10 mol, the monodispersity of an inorganic nanoparticle can be improved more and aggregation will not occur.

As the dispersant, an organic compound having a group that adsorbs to the surface of the inorganic nanoparticles is preferable. Specifically, it has 1 to 3 amino groups, carboxy groups, sulfonic acid groups, hydroxy groups or sulfinic acid groups, and these can be used alone or in combination.
As structural formulas, R—NH ₂ , H ₂ N—R—NH ₂ , H ₂ N—R (NH ₂ ) —NH ₂ , R—COOH, HOCO—R—COOH, HOCO—R (COOH) —COOH _{, R-SO 3 H, HOSO} 2 -R-SO 3 H, HOSO 2 -R (SO 3 H) -SO 3 H, R-SO 2 H, HOSO-R-SO 2 H, HOSO-R (SO 2 H) —SO ₂ H, R—OH, a compound represented by HO—R—OH, wherein R is a linear, branched or cyclic saturated or unsaturated hydrocarbon residue. Examples of such a dispersant include oleic acid, oleylamine, erucic acid, linoleic acid and the like.

  Although the addition time of a dispersing agent is not specifically limited, It is preferable to be between the time immediately after reaction and the following ripening process start. By adding such a dispersant, it is possible to obtain inorganic nanoparticles that are more monodispersed and have no aggregation.

The production method of the present invention may include a step of aging by raising the temperature after completion of the reaction, if necessary.
The aging temperature is preferably a constant temperature of 30 to 90 ° C., and the temperature is suitably higher than the temperature of the reaction. The aging time is preferably 5 to 180 minutes. When the aging temperature and aging time are within the above ranges, aggregation and precipitation are unlikely to occur, the reaction is completed, and the composition can be made constant.

  Here, the “constant temperature” is synonymous with the temperature of the reduction reaction (where “reduction temperature” is the “aging temperature”), but in particular, the range of the above aging temperature (30 It is preferably 5 ° C. or higher, more preferably 10 ° C. or higher, than the temperature of the reduction reaction. By increasing the temperature by 5 ° C. or more, a composition as prescribed can be obtained.

After the aging, after returning to room temperature, the solution after aging is washed with a mixed solution of water and a primary alcohol, and then subjected to a precipitation treatment with a primary alcohol to form a precipitate. It is preferable to provide a washing / purifying step for dispersing the precipitate with an organic solvent. By providing such a cleaning / purification step, impurities are removed and a pure inorganic nanoparticle dispersion can be obtained.
The washing and purification are preferably performed at least once, preferably twice or more each.

  The primary alcohol used for washing and purification is not particularly limited, but methanol, ethanol and the like are preferable. The volume mixing ratio of water and primary alcohol (water / primary alcohol) is preferably in the range of 10/1 to 2/1, and more preferably in the range of 5/1 to 3/1. When the ratio of water is high, the surfactant may be difficult to remove, and conversely, when the ratio of primary alcohol is high, aggregation may occur.

  As described above, inorganic nanoparticles dispersed in the solution can be obtained. Since the inorganic nanoparticles are monodispersed, even when applied to a support, they can be kept uniformly dispersed without agglomeration.

In the present invention, the particle diameter of the inorganic nanoparticles before annealing can be controlled by the water droplet diameter in the reverse micelle, and the water droplet diameter is changed by changing the molar ratio of H ₂ O / surfactant. _If the molar ratio of ₂ O / surfactant is large, the particle size is large. Conversely, if the molar ratio of H ₂ O / surfactant is small, the particle size is small.

  In order to evaluate the particle size of the inorganic nanoparticles obtained by the present invention, the negative image obtained by placing the particles on a mesh for an electron microscope (TEM) is measured using the analysis software of KS-300 manufactured by Carl Zeiss. Is possible. The number average particle size, the coefficient of variation of the particle size, and the abundance of coalesced particles can be compared.

  The features of the present invention will be described more specifically with reference to the following examples. The materials, amounts used, composition ratios, synthesis methods, medium production methods, and the like shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Accordingly, the scope of the present invention should not be construed as being limited by the specific examples shown below.

<Reverse micelle solution>
[Example 1]
12 g (0.027 mol) of aerosol OT (trade name, manufactured by Tokyo Chemical Industry Co., Ltd.) was added to 12 ml of a 2% by weight aqueous solution of L-ascorbic acid (1.36 mmol of ascorbic acid, 0.65 mol of water) in decane A decane solution dissolved in 120 ml (87.6 g, 0.62 mol) was added, and further 1-hexanol was mixed with 1.3 ml (1.07 g, 0.011 mol). A reverse micelle solution (A) having a volume of 145 ml was prepared. Thereafter, difference in solubility parameter (25 ° C.) = (Solubility parameter of hydrophilic organic solvent) − (solubility parameter of hydrophobic organic solvent), difference in inorganic value / organic value ratio = (inorganic property of hydrophilic organic solvent) Value / organic value ratio)-(surfactant inorganic value / organic value ratio). From this equation, the difference in solubility parameter is 2.6, and the difference in inorganic value / organic value ratio is -0.1. 1-Hexanol is 76 millimoles per liter of total volume. The number of moles of the hydrophilic organic solvent here is (the amount of added hydrophilic organic solvent mol) / (volume of water used for reverse micelle formation + volume of hydrophobic organic solvent used for reverse micelle formation + hydrophilicity. It is calculated based on the calculation of (volume of organic solvent).

[Example 2]
A reverse micelle solution (B) was prepared in the same manner as in Example 1 except that the amount of a 1% by mass aqueous solution of L-ascorbic acid was 24 ml. The difference in solubility parameter is 2.6, and the difference in inorganic value / organic value ratio is -0.1. 1-Hexanol is 70 millimoles per liter of total volume.

Example 3
A reverse micelle solution (C) was prepared in the same manner as in Example 1, except that 1.3 ml of 1-hexanol was changed to 1 ml of 1-butanol. The difference in solubility parameter is 3.5, and the difference in inorganic value / organic value ratio is 0.4. 1-butanol is 76 millimoles per liter of total volume.

Example 4
A reverse micelle solution (D) was prepared in the same manner as in Example 1 except that 1.3 ml of 1-hexanol was changed to 1.7 ml of 1-octanol. The difference in solubility parameter is 1.7, and the difference in inorganic value / organic value ratio is -0.3. 1-octanol is 75 millimoles per liter of total volume.

Example 5
A reverse micelle solution (E) was prepared in the same manner as in Example 1 except that 1.3 ml of 1-hexanol was changed to 1.1 ml of benzyl alcohol. The difference in solubility parameter is 3.9, and the difference in inorganic value / organic value ratio is -0.1. Benzyl alcohol is 76 mmol per liter of total volume.

Example 6
A reverse micelle solution (F) was prepared in the same manner as in Example 1, except that 120 ml of decane was changed to 120 ml of octane (84 g, 0.74 mol). The difference in solubility parameter is 2.7, and the difference in inorganic value / organic value ratio is -0.1. 1-Hexanol is 76 millimoles per liter of total volume.

[Comparative Example 1]
A reverse micelle solution (a) to which no hydrophilic organic solvent was added was prepared for Example 1.

[Comparative Example 2]
A reverse micelle solution (b) having a total volume of 152 ml was prepared in the same manner as in Example 1 except that 1.3 ml of 1-hexanol was changed to 9.6 ml (7.87 g, 0.077 mol). Prepared. 1-Hexanol is 507 mmol per liter total volume.

[Evaluation of reverse micelle solution]
Regarding the reverse micelle solutions (A) to (F) of the example and the reverse micelle solutions (a) and (b) of the comparative example, after stirring for 30 minutes with a magnetic stirrer, whether the reverse micelles phase separate upon standing? I checked.
As a result, the reverse micelle solutions (A) to (F) of the examples corresponding to the present invention did not undergo phase separation even after standing for about 1 month. On the other hand, the reverse micelle solutions (a) and (b) of the comparative example were phase-separated within a few hours. This revealed that the reverse micelle solution of the present invention is very stable.

<Inorganic nanoparticle dispersion>
Example 7
The following operation was performed in high purity N ₂ gas.
Triammonium iron oxalate (Fe (NH ₄ ) ₃ (C ₂ O ₄ ) ₃ ) (manufactured by Wako Pure Chemical Industries, Ltd.) 0.30 g and potassium chloroplatinate (K ₂ PtCl ₄ ) (Wako Pure Chemical Industries, Ltd. )) In a metal salt aqueous solution in which 0.29 g is dissolved in 36 ml of H ₂ O (deionized and deoxygenated), 12 g of aerosol OT (trade name, manufactured by Tokyo Chemical Industry Co., Ltd.) is decaned (Wako Pure Chemical ( Alkane solution dissolved in 120 ml) and 1.3 ml of 1-hexanol (1.07 g, 10.5 mmol) were added and mixed to prepare a reverse micelle solution (I) having a total volume of 169 ml.

An alkane solution in which 0.48 g of NaBH ₄ (manufactured by Wako Pure Chemical Industries, Ltd.) is dissolved in 36 ml of H ₂ O (deoxygenated), 12 g of aerosol OT in 120 ml of decane, and 1.3 ml of 1-hexanol are dissolved. Were added and mixed to prepare a reverse micelle solution (II) having a total volume of 169 ml.

NaBH ₄ 0.12 g of the reducing agent aqueous solution prepared by dissolving 8 wt% of NaOH5ml _{+ H} 2 O (deoxygenated) 4 ml, alkane solution obtained by dissolving the aerosol OT3g decane 30ml and 1-hexanol 0.33 ml (0.27 g, 2.65 mmol) was added and mixed to prepare a reverse micelle solution (III) having a total volume of 42 ml.

An alkane solution in which 0.09 g of L-ascorbic acid (manufactured by Wako Pure Chemical Industries, Ltd.) is dissolved in 4 ml of 8% by weight NaOH 5 ml + H ₂ O (deoxygenated), 3 g of aerosol OT dissolved in 30 ml of decane, and 0.33 ml of 1-hexanol was added and mixed to prepare a reverse micelle solution (IV) having a total volume of 42 ml.

To an aqueous reducing agent solution in which 0.12 g of NaBH ₄ was dissolved in 1 ml of 8% by weight NaOH + 8 ml of H ₂ O (deoxygenated), an alkane solution in which 3 g of aerosol OT was dissolved in 30 ml of decane and 0.33 ml of 1-hexanol were added and mixed. Thus, a reverse micelle solution (V) having a total volume of 42 ml was prepared.

  The reverse micelle solution (II) was set at 22 ° C., and the reverse micelle solution (I) was added over 3 minutes while stirring at a rotation of 300 rpm using a Teflon (registered trademark) blade. Seven minutes after the start, reverse micelle solution (III) was added. Moreover, 9 mL of oleylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) was added 9 minutes after the start. Further, 11 minutes after the start, reverse micelle solution (IV) was added instantaneously. After 13 minutes from the start, the temperature was raised to 40 ° C., followed by aging for 180 minutes. Reverse micelle solution (V) was added during 60 minutes of aging.

After cooling to room temperature, 3 ml of oleic acid (manufactured by Wako Pure Chemical Industries, Ltd.) was added, mixed, and taken out into the atmosphere. In order to destroy the reverse micelle, a mixed solution of 450 ml of H ₂ O and 450 ml of methanol was added to separate into an aqueous phase and an oil phase. A state in which nanoparticles were dispersed on the oil phase side was obtained. The oil phase side was washed once with 900 ml of H ₂ O + 300 ml of methanol. Thereafter, 300 ml of ethanol was added to the supernatant and centrifuged at 3000 rpm for 10 minutes to precipitate the nanoparticles. The supernatant was removed, and 40 ml of heptane (manufactured by Wako Pure Chemical Industries, Ltd.) was added and redispersed. Furthermore, 40 ml of ethanol was added, and the same centrifugal separation operation as described above was performed to precipitate the nanoparticles. This operation was further performed twice, and finally 15 ml of heptane, 75 μl of octylamine and 75 μl of oleic acid were added to obtain a FePt nanoparticle dispersion (G).

Example 8
For Example 7, 1-hexanol of reverse micelle solution (I) and reverse micelle solution (II) was 1.7 ml each of 1-octanol, and 1-hexanol of reverse micelle solutions (III) to (V) was 1-octanol. A FePt nanoparticle dispersion liquid (H) was obtained in the same manner as in Example 7 except that each volume was changed to 0.43 ml.

[Comparative Example 3]
The FePt nanoparticle dispersion liquid (c) was obtained in the same manner as in Example 7 except that 1-hexanol of the reverse micelle solutions (I) to (V) was removed.

[Comparative Example 4]
Example 7 is different from Example 7 except that 1-hexanol of reverse micelle solutions (I) and (II) is changed to 12 ml each and 1-hexanol of reverse micelle solutions (III) to (V) is changed to 3.05 ml each. In the same manner as in No. 7, an FePt nanoparticle dispersion liquid (d) was obtained.

[Comparative Example 5]
Compared to Example 7, except that 1-hexanol of reverse micelle solutions (I) to (V) is changed to methanol (solubility parameter: 13.9, inorganic value / organic value ratio: 5) It carried out similarly and obtained the FePt nanoparticle dispersion liquid (e).

Example 9
The following operation was performed in high purity N ₂ gas.
To a metal salt aqueous solution obtained by dissolving 0.80 g of sodium chloroaurate (Na (AuCl ₄ ) · 2H ₂ O) (manufactured by Wako Pure Chemical Industries, Ltd.) in 18 ml of H ₂ O (deionized and deoxygenated), aerosol was added. Alkane solution obtained by dissolving 12 g of OT (trade name, manufactured by Tokyo Chemical Industry Co., Ltd.) in 120 ml of decane (manufactured by Wako Pure Chemical Industries, Ltd.) and 1.3 ml of 1-hexanol (1.07 g, 10.5 mmol) were added. By mixing, a reverse micelle solution (I) having a total volume of 151 ml was prepared.

An alkane solution in which 0.57 g of NaBH ₄ (manufactured by Wako Pure Chemical Industries, Ltd.) is dissolved in 18 ml of H ₂ O (deoxygenated), 12 g of aerosol OT dissolved in 120 ml of decane, and 1.3 ml of 1-hexanol. Were added and mixed to prepare a reverse micelle solution (II) having a total volume of 151 ml.

In an aqueous reducing agent solution in which 0.14 g of NaBH ₄ was dissolved in 3.5 ml of 8% by weight NaOH + 3.5 ml of H ₂ O (deoxygenated), an alkane solution in which 3 g of aerosol OT was dissolved in 30 ml of decane and 0.33 ml (0. 27 g, 2.65 mmol) was added and mixed to prepare a reverse micelle solution (III) with a total volume of 38 ml.

  The reverse micelle solution (II) was set at 22 ° C., and the reverse micelle solution (I) was added instantaneously while stirring at a rotation of 250 rpm using a Teflon (registered trademark) blade. Reverse micelle solution (III) was added 4 minutes after the start. Moreover, 3 mL of oleylamine (Tokyo Kasei Co., Ltd.) was added 6 minutes after the start. Further, 8 minutes after the start, the temperature was raised to 40 ° C., and then aging was performed for 120 minutes.

After cooling to room temperature, 2 ml of 1-dodecanethiol (manufactured by Wako Pure Chemical Industries, Ltd.) was added, mixed, and taken out into the atmosphere. In order to destroy the reverse micelle, a mixed solution of 450 ml of H ₂ O and 450 ml of methanol was added to separate into an aqueous phase and an oil phase. A state in which the metal nanoparticles were dispersed on the oil phase side was obtained. The oil phase side was washed once with 900 ml of H ₂ O + 300 ml of methanol. Thereafter, 300 ml of ethanol was added to the supernatant and centrifuged at 3000 rpm for 10 minutes to precipitate the nanoparticles. The supernatant was removed, and 40 ml of heptane (manufactured by Wako Pure Chemical Industries, Ltd.) was added and redispersed. Furthermore, 40 ml of ethanol was added, and the same centrifugal separation operation as described above was performed to precipitate the nanoparticles. This operation was further performed twice, and finally 15 ml of heptane was added to obtain an Au nanoparticle dispersion (J).

[Comparative Example 6]
An Au nanoparticle dispersion liquid (f) was obtained in the same manner as in Example 9, except that 1-hexanol of the reverse micelle solutions (I) to (III) was removed.

Example 10
Aerosol OT (trade name, Tokyo Chemical Industry Co., Ltd.) was added to an aqueous metal salt solution in which 0.68 g of zinc chloride (ZnCl ₂ ) (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in 36 ml of H ₂ O (deionized and deoxygenated). )) Alkane solution obtained by dissolving 12 g in 120 ml of decane (manufactured by Wako Pure Chemical Industries, Ltd.) and 1.3 ml (1.07 g, 10.5 mmol) of 1-hexanol were added and mixed, and the total volume was 169 ml. A micelle solution (I) was prepared.

In an aqueous reducing agent solution obtained by dissolving 1.6 g of NaOH (manufactured by Wako Pure Chemical Industries, Ltd.) in 35 ml of H ₂ O (deoxygenated), an alkane solution obtained by dissolving 12 g of aerosol OT in 120 ml of decane and 1.3 ml of 1-hexanol. By adding and mixing, a reverse micelle solution (II) having a total volume of 169 ml was prepared.

  The reverse micelle solution (II) was set at 22 ° C., and the reverse micelle solution (I) was added instantaneously while stirring at a rotation of 250 rpm using a Teflon (registered trademark) blade. After 8 minutes from the start, the temperature was raised to 60 ° C. and then aged for 120 minutes.

After cooling to room temperature, in order to destroy the reverse micelle, a mixed solution of 200 ml of H ₂ O and 200 ml of methanol was added to separate into an aqueous phase and an oil phase. A state in which nanoparticles were dispersed on the aqueous phase side was obtained. The aqueous phase side was taken out and washed twice with 300 ml of heptane + 300 ml of methanol. Thereafter, ultrafiltration was performed while adding H ₂ O to the aqueous phase side to remove impurities as much as possible. Finally, a ZnO nanoparticle dispersion (K) was obtained. The conductivity was 30 μS / cm as measured by HORIBA 480C at 25 ° C.

[Comparative Example 7]
Example 10 was carried out in the same manner as in Example 10 except that 1-hexanol in the reverse micelle solutions (I) and (II) was removed to obtain a ZnO nanoparticle dispersion liquid (g).

[Comparative Example 8]
A ZnO nanoparticle dispersion liquid (h) was obtained in the same manner as in Example 10, except that 1-hexanol in the reverse micelle solutions (I) and (II) was changed to methanol.

<Evaluation of inorganic nanoparticles>
For the inorganic nanoparticle dispersion liquids (G), (H), (J), (K) of the examples and the inorganic nanoparticle dispersion liquids (c) to (h) of the comparative examples, each particle was used for an electron microscope (TEM). The negatives photographed on the mesh were measured using KS-300 analysis software manufactured by Carl Zeiss, and the number average particle diameter, the coefficient of variation of the particle diameter, and the abundance of coalesced particles were compared.
As is clear from Table 1, the nanoparticles of the inorganic nanoparticle dispersions (G) to (J) of the present invention have a particle size of the nanoparticles of the comparative inorganic nanoparticle dispersions (c) to (h). The coefficient of variation was small, and the abundance of coalesced particles was also low.

Claims (6)

  Water, a hydrophobic organic solvent, a surfactant, and a hydrophilic organic solvent having a solubility parameter difference of 0 to 5 based on the hydrophobic organic solvent, the hydrophilic organic solvent having a total volume of 1 Reverse micelle solution that is 2 millimoles to 300 millimoles per liter.   Water, a hydrophobic organic solvent, a surfactant, and a hydrophilic organic solvent having a difference of an inorganic value / organic value ratio within ± 1.5 based on the surfactant, the hydrophilic Reverse micelle solution in which the organic solvent is 2 to 300 mmol per liter of the total volume.   The reverse micelle solution according to claim 1 or 2, wherein the surfactant is contained in an amount of 50 mmol to 500 mmol with respect to 1 liter of the hydrophobic organic solvent.   The reverse micelle solution according to any one of claims 1 to 3, wherein the water is 1 mol to 300 mol with respect to 1 mol of the surfactant.   An inorganic nanoparticle produced using the reverse micelle solution according to any one of claims 1 to 4.   The manufacturing method of an inorganic nanoparticle including using the reverse micelle liquid of any one of Claims 1-4.