JP2006056999A - Polymer-modified nanoparticle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To economically provide polymer-modified metal oxide nanoparticles stably existing without causing aggregation over a long period and to provide a transparent colloid solution containing the polymer-modified metal oxide nanoparticles. <P>SOLUTION: The polymer-modified nanoparticles are obtained by carrying out surface modification of metal oxide nanoparticles having ≤100 nm number-average particle diameter with a polymer obtained by a reversible addition-elimination chain transfer polymerization using a thiocarbonylthio compound as a chain transfer agent. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to polymer-modified nanoparticles. More specifically, the present invention relates to nanoparticles obtained by surface-modifying metal oxide nanoparticles having a particle diameter of 100 nm or less with a polymer. The present invention also relates to a transparent colloidal solution containing polymer-modified nanoparticles.

  Metal oxide nanoparticles exhibit properties that cannot be seen in bulk, such as fluorescence depending on their size, due to their quantum effects, so applications are being developed in a wide range of fields such as electronics, optics, optoelectronics, and bioscience. . For example, a solar cell, a light emitting diode, an ultraviolet shielding agent, a wavelength conversion material, a photocatalyst, a quantum dot, and the like.

  However, metal oxide nanoparticles are very unstable due to their high surface activity, and have a problem that they are aggregated in a solution or at the time of isolation, and the quantum effect depending on the nanosize is lost. For example, Non-Patent Document 1 discloses a transmission electron microscope (TEM) photograph of zinc oxide particles, and it can be seen that the particles are aggregated. Non-Patent Document 2 describes a phenomenon in which particles aggregate when a colloidal solution of zinc oxide is concentrated.

  Various techniques have been proposed for the purpose of preventing such aggregation of metal oxide nanoparticles. For example, Patent Document 1 and Non-Patent Document 3 describe the synthesis of metal oxide nanoparticles surface-modified with a low-molecular compound such as trioctylphosphine, trioctylphosphine oxide, alkylamine, hexametaphosphoric acid, and the like. However, in the case of surface modification with these low molecular weight compounds, there is a problem in stability, and there is a problem that nanoparticles are aggregated in about several days to several weeks. Moreover, it was difficult to disperse the metal oxide nanoparticles surface-modified with a low molecular compound in the resin. On the other hand, techniques for modifying the surface of metal oxide nanoparticles with a polymer compound are described in Non-Patent Document 4, Patent Document 2, and the like. However, the modification with polyvinylpyrrolidone described in Non-Patent Document 4 has a problem in stability because the bond with the nanoparticles is not strong. Polyethylene glycol having an SH group at the end described in Patent Document 2 can strongly modify the metal oxide nanoparticle surface by the action of the SH group, but the synthesis of such a polymer is complicated, It was not economical.

A technique considered to be the simplest as a method for synthesizing a polymer having an SH group at the terminal is a reversible addition-elimination chain transfer polymerization method, which is described in Patent Document 3 and Patent Document 4. In particular, in Patent Document 4, surface modification of metal nanoparticles is performed using a polymer obtained by reversible addition / desorption chain transfer polymerization. However, since the applicable nanoparticles are limited to those synthesized by a reduction method, the surface modification of metal oxide nanoparticles could not be performed.
JP 2003-226521 A WO02 / 018080 JP 2002-265508 A US2003 / 0199653 A1 D. W. Bahnemann et al. , J. et al. Phys. Chem. 1987, 91, 3789. L. Spanhel et al. , J. et al. Am. Chem. Soc. 1991, 113, 2826. M.M. Shim et al. , J. et al. Am. Chem. Soc. 2001, 123, 11651. L. Guo et al. Chem. Mater. 2000, 12, 2268.

  The problem to be solved by the present invention is to economically provide polymer-modified metal oxide nanoparticles that do not aggregate over a long period of time and exist stably.

  As means for solving the above problems, the present inventors propose the following polymer-modified metal oxide nanoparticles.

  That is, the polymer-modified nanoparticle of the present invention uses a polymer obtained by reversible addition / desorption chain transfer polymerization using a metal oxide nanoparticle having a number average particle diameter of 100 nm or less and a thiocarbonylthio compound as a chain transfer agent. It is obtained by surface modification.

  In a preferred embodiment of the present invention, the polymer used for the surface modification is a polymer that is terminally SH-treated by a treating agent after reversible addition-elimination chain transfer polymerization using a thiocarbonylthio compound as a chain transfer agent. .

  In a preferred embodiment of the present invention, the treating agent is selected from the group consisting of a hydrogen-nitrogen bond-containing compound, a basic compound, and a reducing agent.

  In a preferred embodiment of the present invention, the polymer used for the surface modification is (meth) acrylic acid ester, (meth) acrylamides, (meth) acrylic acid, styrene, sodium p-styrenesulfonate, (vinylbenzyl) One or more monomers selected from the group consisting of trimethylammonium chloride, acrylonitrile, vinyl pyrrolidone, vinyl pyridine, vinyl acetate, vinyl chloride, maleic anhydride and maleimide are polymerized.

  In a preferred embodiment of the present invention, the polymer used for the surface modification has a molecular weight distribution of 1.5 or less.

  In a preferred embodiment of the present invention, the number average particle diameter of the metal oxide nanoparticles is 10 nm or less.

  In a preferred embodiment of the present invention, the metal oxide nanoparticles are obtained by reacting an organometallic compound and an OH group-containing basic compound in a solvent.

  In a preferred embodiment of the present invention, the OH group-containing basic compound is a compound selected from the group consisting of LiOH, NaOH, and KOH.

  In a preferred embodiment of the present invention, the organometallic compound is zinc acetate, zinc acetate dihydrate, zinc acetylacetonate hydrate, zinc benzoate, zinc citrate, zinc dibutyldithiocarbamate, diethyldithiocarbamate. It is a compound selected from the group consisting of zinc, zinc formate, zinc formate dihydrate, zinc laurate, and zinc salicylate trihydrate.

  In a preferred embodiment of the present invention, the metal oxide nanoparticles may be Zn, Ti, Zr, Cr, Mo, W, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Cu, Ag, It is doped with an element selected from the group consisting of Cd, Al, Ga, In, Si, Ge, Sn, Pb, lanthanoid and actinoid.

  The present invention also includes a transparent colloid solution containing the polymer-modified nanoparticles.

  The polymer-modified nanoparticles of the present invention are stable in any of an isolated state, a colloid solution state, and a dispersed state in a resin, and exist without being aggregated over a long period of time. Therefore, electrical characteristics, optical characteristics, and chemical characteristics are maintained without loss. That is, when it is used as a light emitting device such as a display or a light emitting diode, it has a long life and little deterioration. It can be used for a long period of time while maintaining its performance as a wavelength conversion element and quantum dot. When used as a catalyst, performance degradation is small. In addition, the composition and structure of the polymer to be modified can be arbitrarily selected, so the physical properties of the metal nanoparticle surface, such as hydrophilicity, lipophilicity, and amphiphilicity, can be freely adjusted, and dispersed and compatible with various solvents and resins. Is easy.

  The polymer-modified nanoparticles of the present invention can be obtained by surface-modifying metal oxide nanoparticles using a polymer obtained by reversible addition / desorption chain transfer polymerization using a thiocarbonylthio compound as a chain transfer agent.

  The reversible addition / elimination chain transfer polymerization using the thiocarbonylthio compound as a chain transfer agent is not particularly limited, and examples thereof include “HANDBOOK OF RADICAL POLYMERIZATION”, K.A. Matyjaszewski and T.M. P. Davis Ed. , Wiley, 2002, page 661, or the method described in the reference described in the book can be applied. However, it is preferable to make it react at the temperature of 70 degreeC or more from a reactive point, and 80 degreeC or more is more preferable. The form of polymerization is not limited to bulk polymerization, solution polymerization, emulsion polymerization, suspension polymerization and the like, but bulk polymerization or solution polymerization is preferable in that post-treatment after polymerization is easy.

  The thiocarbonylthio compound used in the present invention is not particularly limited, but the following compounds are preferable in view of availability and reactivity;

（式中、Ｍｅはメチル基、Ｅｔはエチル基、Ｐｈはフェニル基、Ａｃはアセチル基を表し、ｒは１以上の整数である）。これらのチオカルボニルチオ化合物のうちより好ましいものとしてはトリチオカーボネート構造を有する化合物、あるいは１分子中に複数のチオカルボニルチオ構造を有する化合物を挙げることができる。トリチオカーボネート構造を有する化合物は一般に可逆的付加脱離連鎖移動重合の反応性が高い。１分子中に複数のチオカルボニルチオ構造を有する化合物は、金属酸化物ナノ粒子表面に複数点で結合するため強固に表面修飾することができ、また金属酸化物ナノ粒子同士を架橋するように修飾することも可能であるため、金属酸化物ナノ粒子間の距離を制御しながら緻密に配列させることが可能となる。

(In the formula, Me represents a methyl group, Et represents an ethyl group, Ph represents a phenyl group, Ac represents an acetyl group, and r is an integer of 1 or more). Among these thiocarbonylthio compounds, more preferred are compounds having a trithiocarbonate structure or compounds having a plurality of thiocarbonylthio structures in one molecule. A compound having a trithiocarbonate structure is generally highly reactive in reversible addition / elimination chain transfer polymerization. A compound having a plurality of thiocarbonylthio structures in one molecule can be strongly modified because it binds to the surface of the metal oxide nanoparticles at multiple points, and is modified so as to crosslink the metal oxide nanoparticles. Therefore, it is possible to arrange them precisely while controlling the distance between the metal oxide nanoparticles.

  When modifying the surface of the metal oxide nanoparticles using the polymer obtained by the above reversible addition / desorption chain transfer polymerization, the polymer may be used as it is, but a treatment agent is used in terms of high surface modification efficiency. It is preferable to use terminal SH. Although it does not specifically limit as a processing agent, The compound chosen from the group which consists of a hydrogen-nitrogen bond containing compound, a basic compound, and a reducing agent is preferable at the point that the efficiency which converts into SH group is high.

  Among the above-mentioned treatment agents, the hydrogen-nitrogen bond-containing compound is not particularly limited, but ammonia, hydrazine, primary amine, secondary amine, amide compound, amine hydrochloride, hydrogen-nitrogen bond-containing polymer, hindered amine light stability An agent (HALS) etc. can be mentioned. Examples of the primary amine include methylamine, ethylamine, isopropylamine, n-propylamine, n-butylamine, t-butylamine, 2-ethylhexylamine, 2-aminoethanol, ethylenediamine, diethylenetriamine, and 1,2-diaminopropane. 1,4-diaminobutane, cyclohexylamine, aniline, phenethylamine and the like. Examples of the secondary amine include dimethylamine, diethylamine, diisobutylamine, di-2-ethylhexylamine, iminodiacetic acid, bis (hydroxyethyl) amine, di-n-butylamine, di-t-butylamine, diphenylamine, N- Mention may be made of methylaniline, imidazole, piperidine and the like. Examples of the amide compound include adipic acid hydrazide, N-isopropylacrylamide, oleic acid amide, thioacetamide, formamide, acetanilide, phthalimide, succinimide and the like. Examples of the amine hydrochloride include acetamidine hydrochloride, monomethylamine hydrochloride, dimethylamine hydrochloride, monoethylamine hydrochloride, diethylamine hydrochloride, guanidine hydrochloride and the like. Examples of the hydrogen-nitrogen bond-containing polymer include polyethyleneimine, polyallylamine, and polyvinylamine. Examples of the HALS include ADK STAB LA-77 (Asahi Denka Kogyo Co., Ltd.), Tinuvin 144 (Ciba Specialty Chemicals Co., Ltd.), ADK STAB LA-67 (Asahi Denka Kogyo Co., Ltd.) and the like. Can do.

  Among the above-mentioned treatment agents, examples of basic compounds are not particularly limited, but sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, sodium methoxide, sodium ethoxide, magnesium methoxide, carbonic acid Examples thereof include sodium and potassium carbonate.

Among the above-mentioned treatment agents, examples of the reducing agent are not particularly limited, and examples thereof include sodium hydride, lithium hydride, calcium hydride, LiAlH ₄ , NaBH ₄ , LiBEt ₃ H (super hydride), and hydrogen.

  The said processing agent may be used independently and may be used in combination. From the viewpoint of reactivity, a hydrogen-nitrogen bond-containing compound and a reducing agent are preferred. In the case of a hydrogen-nitrogen bond-containing compound, a compound having a boiling point of 20 ° C. to 200 ° C. is more preferable in terms of easy purification. Although the usage-amount of the said processing agent is not specifically limited, 0.01-100 weight part is preferable with respect to 100 weight part of polymers at a reactive and economical point, and 0.1-50 weight part is more preferable. Reaction conditions such as temperature, the presence or absence of a solvent, and mixing conditions are not particularly limited.

  In the present invention, the composition of the polymer that modifies the surface of the metal oxide nanoparticles is not particularly limited, but the availability, compatibility with various solvents and resins, heat resistance, stability, safety to the human body and the environment. (Meth) acrylic acid esters, (meth) acrylamides, (meth) acrylic acid, styrene, sodium p-styrenesulfonate, (vinylbenzyl) trimethylammonium chloride, acrylonitrile, vinylpyrrolidone, vinylpyridine, vinyl acetate, A polymer obtained by polymerizing at least one monomer selected from the group consisting of vinyl chloride, maleic anhydride, and maleimide is preferred. When a plurality of monomers are polymerized, the main chain structure is not particularly limited, and may be any random copolymer, block copolymer, gradient copolymer, or a combination thereof.

  Among the above monomers, (meth) acrylic acid ester is not particularly limited, but methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, ( Examples include 2-ethylhexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, allyl (meth) acrylate, and phenyl (meth) acrylate. Although it does not specifically limit as (meth) acrylamide, (meth) acrylamide, N-isopropyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide etc. can be mentioned.

  In the present invention, the molecular weight and molecular weight distribution of the polymer that modifies the surface of the metal oxide nanoparticles are not particularly limited, but the number average molecular weight is 3000 to 50000 in that it can be easily controlled by reversible addition / desorption chain transfer polymerization. It is preferable that it exists in the range. In addition, the molecular weight distribution is preferably 1.5 or less, and more preferably 1.2 or less, from the viewpoint that the physical properties of the resulting polymer-modified nanoparticles are uniform. Here, the number average molecular weight (Mn) and the weight average molecular weight (Mw) are values analyzed by gel permeation chromatography (GPC), and the molecular weight distribution is a value calculated as Mw / Mn.

  The metal oxide nanoparticles used in the present invention are not particularly limited as long as the number average particle diameter is 100 nm or less. The number average particle diameter can be determined by dynamic light scattering (DLS) analysis or transmission electron microscope (TEM) observation. The number average particle diameter of the metal oxide nanoparticles is preferably 20 nm or less, and more preferably 10 nm or less, in that the quantum effect appears remarkably. In the present invention, when the metal oxide nanoparticles are columnar or rod-shaped, the shorter diameter is expressed as the number average particle diameter.

  The method for synthesizing the metal oxide nanoparticles used in the present invention is not particularly limited, and is a lithography method, a mechanical grinding method, a top-down method such as laser beam decomposition; a chemical synthesis method, a laser trap method, a gas deposition method (CVD) ) Bottom-up method such as 2-photon confocal method is applicable. Of these, the bottom-up method is preferable in that the particle diameter and particle shape can be controlled, and the chemical synthesis method is more preferable in that the apparatus is inexpensive. Examples of the chemical synthesis method include a coprecipitation method, a reverse micelle method, and a sol-gel method, but the coprecipitation method and the sol-gel method are particularly preferable in terms of simple operation. Among these, the method of reacting an organometallic compound and an OH group-containing basic compound in a solvent is most preferable from the viewpoint of availability of raw materials, economy, and ease of production.

  The organometallic compound is not particularly limited. For example, zinc acetate, zinc acetate dihydrate, zinc chloride, zinc acetylacetonate hydrate, zinc benzoate, zinc citrate, zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate Zinc compounds such as zinc formate, zinc formate dihydrate, zinc laurate, zinc salicylate trihydrate; titanium (III) chloride, titanium (IV) chloride, titanium (IV) cresylate, titanium (II) oxide Titanium compounds such as acetylacetonate, titanium (IV) ethoxide, titanium (IV) isobutoxide, titanium (IV) methoxide, titanium (IV) n-propoxide, titanium (IV) tetrabutoxide, titanium tetraisopropoxide; acetic acid Cobalt (II) tetrahydrate, acetylacetonato cobalt (II), cobalt benzoate (II), cobalt chloride (II), cobalt citrate (II) dihydrate, cobalt oxalate (II) dihydrate, cobalt stearate (II), cobalt hydroxide and other cobalt compounds; nickel acetate (II) tetrahydrate , Acetylacetonato nickel (II) dihydrate, bis (dibutyldithiocarbamate) nickel (II), nickel chloride (II), nickel formate (II) dihydrate, nickel lactate (II) tetrahydrate Nickel compounds such as nickel stearate (II) and nickel hydroxide (II); copper acetate (II) monohydrate, copper (II) bromide, copper (II) chloride, copper (II) citrate Pentahydrate, copper (II) formate tetrahydrate, copper (II) gluconate, copper (II) oleate, copper (II) phthalate, copper (II) sulfate, copper (II) isopropoxide, Copper compounds such as copper (II) methoxide; cadmium acetate dihydrate, cadmium bromide tetrahydrate Cadmium compounds such as hydrates, cadmium carbonate, cadmium chloride, cadmium formate dihydrate, cadmium stearate, cadmium hydroxide, and the like can be given. Of these, zinc compounds are preferred in that the metal oxide nanoparticles obtained have a large band gap and high safety, and zinc acetate, zinc acetate dihydrate, acetylacetonato zinc hydrate, zinc benzoate, Zinc citrate, zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate, zinc formate, zinc formate dihydrate, zinc laurate, zinc salicylate trihydrate are more preferred. These may be used alone or in combination.

Although it does not specifically limit as said OH group containing basic compound, For example, Alkali metal hydroxides, such as LiOH, NaOH, KOH; Alkaline earth, such as Mg (OH) ₂ , Ca (OH) ₂ , Ba (OH) ₂ Metal hydroxides; ammonium hydroxides such as NH ₄ OH, N (Me) ₄ OH, N (Et) ₄ OH, and the like. Of these, alkali metal hydroxides are preferred in terms of availability and reactivity, and LiOH, NaOH, and KOH are more preferred. These may be used alone or in combination.

  When the organometallic compound and the OH group-containing compound are reacted in a solvent, the solvent is not particularly limited, and any one that can dissolve or disperse the organometallic compound and the OH group-containing compound can be arbitrarily used. Examples of such solvents include water; alcohol solvents such as methanol, ethanol, isopropanol, and n-propanol; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; dimethyl sulfoxide; dimethylformamide; halogens such as chloroform and dichloromethane. Examples thereof include ether solvents such as diethyl ether and tetrahydrofuran; aromatic solvents such as benzene and toluene; hydrocarbon solvents such as pentane, hexane, octane, 2-ethylhexane, and cyclohexane. Of these, water, alcohol solvents, and ketone solvents are preferred in that the dispersibility of the metal oxide to be produced is good. In the step of modifying the metal oxide with the polymer, it is preferable to use a solvent in which the polymer is dissolved. These solvents may be used alone or in combination. In the case of combining a plurality of solvents, the solvents may be mixed with each other or may not be mixed, but the solvents mixed with each other are preferable in terms of efficiency.

  The reaction conditions for reacting the organometallic compound with the OH group-containing compound are not particularly limited, and any temperature, time, addition timing, etc. can be employed. In terms of reaction control, the temperature is preferably in the range of -20 ° C to 100 ° C, more preferably in the range of 0 ° C to 80 ° C. Examples of the reaction method include a controlled double jet precipitation method, a sol-gel method, a chemical precipitation method, and a colloid synthesis method, and are not particularly limited. Am. Chem. Coc. 1991, 113, 2826, Chem. Mater. 2000, 12, 2268, and J.A. Phys. Chem. 1992, 96, 11086, etc. Phys. Chem. 1987, 91, 3789 and J.A. Phys. Chem. The colloidal synthesis method described in B 1998,102,7770 etc. is preferable.

  The metal oxide nanoparticles of the present invention may be a single metal oxide or may be doped with one or more metals. The doping element is not particularly limited, but Zn, Ti, Zr, Cr, Mo, W, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, An element selected from the group consisting of Cu, Ag, Cd, Al, Ga, In, Si, Ge, Sn, Pb, lanthanoid, and actinoid is preferable. These may be used alone or in combination. A method for doping is not particularly limited. Am. Chem. Soc. 2002, 124, 15192, J. MoI. Am. Chem. Soc. 2003, 125, 13205, and J. Org. Am. Chem. Soc. The synthesis method described in 2004, 126, 9387 etc. is preferable.

  When metal oxide nanoparticles are surface-modified using a polymer obtained by reversible addition / desorption chain transfer polymerization using a thiocarbonylthio compound as a chain transfer agent, the method is not particularly limited. For example, a method of synthesizing nanoparticles in a solvent and adding the polymer to the solution; a method of isolating the nanoparticles and adding the polymer to the solution; a method of isolating the nanoparticles, an extruder, a plastmill, a Banbury mixer A method of mixing with a polymer in a molten state using a method; a method of mixing a solution of nanoparticles with a polymer solution; a method of coexisting the above-mentioned polymer when synthesizing nanoparticles; and a method of mixing nanoparticles with polymer And the like. Among these, the method of mixing the nanoparticles and the polymer in the solution is preferable regardless of before and after the reaction because the reaction is simple and the modification efficiency is high. In this case, it is preferable to perform ultrasonic irradiation because the modification efficiency is further increased. Alternatively, the metal oxide nanoparticles may be temporarily modified with a low molecular compound or other polymer and then substituted with the polymer of the present invention for modification. Such temporary modification compounds include low molecular amine compounds such as dodecylamine, tridecylamine and laurylamine; low molecular thiol compounds such as decanethiol and dodecanethiol; and phosphate ester compounds such as trioctylphosphine oxide. Polymers such as polyvinyl pyrrolidone, poly (meth) acrylic acid, polyacrylamide, polyethylene glycol, polyvinyl alcohol, polyamine and the like that do not have an SH group can be exemplified, but are not limited thereto.

  The transparent colloid solution of the present invention is obtained by uniformly dispersing the polymer-modified nanoparticles described above in a solvent. Although it does not specifically limit as a solvent here, It is preferable to use the good solvent with respect to the polymer used for the surface modification at the point that the dispersibility of a nanoparticle is favorable. As a good solvent for the polymer, for example, those described in Polymer Handbook, 4th Edition (John Wiley & Sons Inc., 1999) can be used. The method for preparing the transparent colloid solution of the present invention is not particularly limited, and the polymer-modified nanoparticles may be dispersed in a solvent after isolation. It may be a solution. When preparing the transparent colloidal solution, ultrasonic irradiation, microwave irradiation, or the like may be performed.

  Examples of the present invention are shown below, but are not limited thereto.

  In the present invention, the weight average molecular weight (Mw) and number average molecular weight (Mn) of the polymer were determined by gel permeation chromatography (GPC) analysis. The hydrophobic polymer used was a system manufactured by Waters, and the column was connected with Shodex K-806 and K-805 (manufactured by Showa Denko KK), and chloroform was used as an eluent, and analysis was performed using polystyrene standards. For the hydrophilic polymer, a Shodex LF-804 (manufactured by Showa Denko KK) column was used, and dimethylformamide containing 10 mM of LiBr was used as an eluent and analyzed with a polyethylene glycol standard. When polymerizing the polymer, the monomer reaction rate was determined by gas chromatography (GC) analysis. For GC analysis, the sampling solution is dissolved in an appropriate solvent such as ethyl acetate or ethanol, and capillary column DB-17 (manufactured by J & W SCIENTIFIC INC.) Is used, and gas chromatograph GC-14B (manufactured by Shimadzu Corporation) is used. did. The particle diameter of the metal oxide nanoparticles was observed at an acceleration voltage of 80 kV using a transmission electron microscope (TEM) JEM-1200EX (manufactured by JEOL Ltd.). In the case of a colloid solution sample, the sample was dried and fixed on a mesh on which a collodion film was attached and observed. The number average particle diameter of the nanoparticles was calculated by measuring 100 or more nanoparticles using a vernier caliper in a TEM photograph. As for the emission spectrum, a photoluminescence spectrum was measured in the range of 400 to 700 nm using excitation light of 299 nm using a fluorometer LS55 (manufactured by Perkin Elmer). Ultrasonic irradiation was performed using an ultrasonic homogenizer UH-600 (manufactured by MST Co., Ltd.). The thiocarbonylthio compound used as the chain transfer agent was synthesized according to the method described in JP-T-2000-515181 or Macromolecules 2002, 35, 4123.

(Production Example 1)
Synthesis of poly (acrylic acid / N, N-dimethylacrylamide) having an SH group at the end. A four-necked flask (100 mL) equipped with a reflux condenser with a nitrogen inlet, a magnetic stirrer, and a thermocouple for temperature measurement, N-dimethylformamide (50 mL), azobisisobutyronitrile (5.3 mg), 1-phenylethyldithiobenzoate (42 mg) and acrylic acid (20 mL) were added, and the inside of the reactor was deaerated and purged with nitrogen. The reaction solution was stirred at 60 ° C. with stirring for 4 hours (conversion 21%), cooled to room temperature, dimethylamine (10 mL) was added, and the mixture was stirred for 8 hours. The reaction solution was concentrated and poured into toluene (200 mL) to precipitate a polymer. From the GPC and NMR analysis of the obtained polymer, it was confirmed that the polymer was Mw17200, Mn14300, Mw / Mn1.20 and poly (acrylic acid / N, N-dimethylacrylamide) having an SH group at the terminal. The conversion yield from acrylic acid to acrylamide was 15%.

(Production Example 2)
Synthesis of poly (N, N-dimethylacrylamide) having SH group at the end (PDMA) A four-necked flask (100 mL) equipped with a reflux condenser with a nitrogen inlet, a magnetic stirrer, and a thermocouple for temperature measurement, N-dimethyl-s-thiobenzoylthiopropionamide (232 mg), DMA (30.0 g), N, N-dimethylformamide (10 g), water (20 g), 4,4′-azobis (4-cyanovaleric acid) (69 mg) was added, and the inside of the reactor was deaerated and purged with nitrogen. The mixture was stirred at 80 ° C. for 3 hours and cooled to room temperature. The monomer reaction rate was 44%, and the results of GPC analysis were Mw16800, Mn14200, and Mw / Mn1.18.

  To this solution, 2-ethanolamine (5 g) was added and stirred at 70 ° C. for 3 hours to obtain an aqueous solution of PDMA having a terminal SH group.

(Production Example 3)
Synthesis of polymethyl methacrylate (PMMA) having an SH group at the end 2- (2-phenylpropyl) was added to a 4-neck flask (300 mL) equipped with a reflux condenser with a nitrogen inlet, a magnetic stirrer, and a thermocouple for temperature measurement. ) Dithiobenzoate (0.170 g), MMA (50.0 g), toluene (100 g) and azobisisobutyronitrile (0.021 g) were added, the atmosphere was replaced with nitrogen, and the mixture was heated at 90 ° C. for 2 hours. The monomer reaction rate was 30%. It cooled to 70 degreeC, n-butylamine (0.0935g) was added, and it stirred at 70 degreeC for 10 hours. The reaction solution was poured into methanol (400 mL) to precipitate PMMA (7.4 g) having an SH group at one end. It was Mw31600, Mn26200, and Mw / Mn1.20 as a result of the GPC analysis.

(Production Example 4)
Synthesis of polystyrene having an SH group at the end (PSt) 2- (2-phenylpropyl) dithiobenzoate was added to a 4-neck flask (500 mL) equipped with a reflux condenser with a nitrogen inlet, a magnetic stirrer, and a thermocouple for temperature measurement. (3.22 g), styrene (100.3 g), toluene (98.1 g) and azobisisobutyronitrile (0.61 g) were added, the atmosphere was replaced with nitrogen, and the mixture was stirred at 70 ° C. for 14 hours. The monomer reaction rate was 42%. The reaction solution was kept at 50 ° C., diethylamine (25 g) was added, and the mixture was stirred for 8 hours. After cooling to room temperature, the reaction solution was poured into methanol (500 mL) to precipitate a polymer. The obtained polystyrene was Mw4300, Mn3700, Mw / Mn1.16, and it confirmed that the one terminal was converted into SH group by ¹ H-NMR analysis.

(Production Example 5)
Synthesis of poly (n-butyl acrylate) with SH group at the end (PBA) Dibenzyltrithiocarbonate (4.46 g), acrylic in a 200 mL reactor equipped with a reflux condenser with a nitrogen gas inlet, a stirrer, and a thermometer Acid n-butyl (49.7 g), toluene (50 g) and azobisisobutyronitrile (0.415 g) were added, and the inside of the reactor was deaerated and purged with nitrogen. It stirred at 90 degreeC for 3 hours, sampled, and the production | generation of PBA (Mw4200, Mn3700, Mw / Mn1.15) which has a trithio carbonate structure was confirmed by GPC analysis and NMR analysis.

  N-Butylamine (20 g) was added to this solution and stirred at room temperature for 1 hour, and then poured into hexane (500 mL) and centrifuged to obtain a polymer as a precipitate. By GPC analysis and NMR analysis, it was confirmed to be PBA (Mw 3000, Mn 2700, Mw / Mn 1.11) having an SH group at the terminal.

(Production Example 6)
Synthesis of ZnO nanoparticles Phys. Chem. With reference to the method of B 1998, 102, 7770, ZnO nanoparticles were synthesized as follows.

  Zinc acetate dihydrate (220 mg) was dissolved in 2-propanol (80 mL), stirred at 50 ° C. for 30 minutes, and then 2-propanol was added to make a total volume of 920 mL, followed by cooling to 0 ° C. To this, 0.02 M NaOH / 2-propanol solution (80 mL) was added at once and stirred at 65 ° C. for 2 hours. From TEM analysis, it was confirmed that ZnO nanoparticles having a number average particle diameter of 5.1 nm were generated.

(Production Example 7)
Synthesis of ZnO nanoparticles Phys. Chem. With reference to the method of 1992, 96, 11086, ZnO nanoparticles were synthesized as follows.

Zinc acetate dihydrate (11.0 g) was dissolved in absolute ethanol (500 mL), and ethanol was slowly distilled off while heating to 80 ° C. in a nitrogen atmosphere. When the fraction reached about 300 mL, absolute ethanol (300 mL) was added to the reactor, and LiOH.H ₂ O (2.9 g) was added. Ultrasonic irradiation was performed at room temperature for 2 hours, and the insoluble matter was removed by filtration through a 0.1 μm glass filter. From TEM analysis, it was confirmed that ZnO nanoparticles having a number average particle diameter of 8.5 nm were generated.

(Production Example 8)
Synthesis of Mn-doped ZnO nanoparticles Am. Chem. Soc. With reference to the method of 2004, 126, 9387, Mn-doped ZnO nanoparticles were synthesized as follows.

  Zinc acetate dihydrate (2.15 g) and manganese acetate tetrahydrate (0.05 g) were dissolved in DMSO (100 mL), and tetramethylammonium hydroxide pentahydrate (30.8 g) was added to ethanol. A solution dissolved in (310 mL) was added dropwise with stirring at room temperature. After completion of the dropwise addition, the reaction solution was stirred at 60 ° C. for 4 hours and poured into ethyl acetate (500 mL) to precipitate particles. The obtained particles were dispersed in ethanol (300 mL) and poured into heptane (500 mL) to precipitate. The obtained particles were dispersed in ethanol (200 mL), added with dodecylamine (5 g), stirred at room temperature for 2 hours while irradiating with ultrasonic waves, concentrated with a rotary evaporator, and dissolved in toluene (100 mL). From TEM analysis, it was confirmed that Mn-doped ZnO nanoparticles having a number average particle diameter of 6.7 nm were generated. Mn doping was confirmed from the fact that the emission spectrum near 530 nm was significantly weakened.

Example 1
Poly (acrylic acid / N, N-dimethylacrylamide) (0.5 g) having an SH group at the terminal obtained in Production Example 1 was added to a 2-propanol solution (5 mL) of the ZnO nanoparticles obtained in Production Example 6. Then, the solution was concentrated and hexane (10 mL) was added to precipitate polymer-modified ZnO nanoparticles. The obtained polymer-modified ZnO nanoparticles were dissolved in methanol (1 mL) and purified by pouring into hexane (10 mL) for reprecipitation. The obtained polymer-modified ZnO nanoparticles showed an emission spectrum at 510 nm in methanol, and were confirmed to contain ZnO nanoparticles from TEM observation. Aggregation of ZnO nanoparticles was not observed in the TEM observation.

(Example 2)
Poly (acrylic acid / N, N-dimethylacrylamide) (2 g) having an SH group at the end obtained in Production Example 1 was dissolved in an ethanol solution (5 mL) of ZnO nanoparticles obtained in Production Example 7, Ultrasonic irradiation was performed at room temperature for 1 hour. The obtained colloidal solution of the polymer-modified ZnO nanoparticles remained transparent even after being left at room temperature for 6 months or more. As a result of TEM observation, it was confirmed that the ZnO nanoparticles existed without agglomeration.

(Comparative Example 1)
Commercially available polyacrylic acid (Mw2000, Aldrich) (2 g) was dissolved in an ethanol solution (5 mL) of the ZnO nanoparticles obtained in Production Example 7, and ultrasonic irradiation was performed at room temperature for 1 hour. 2 mL of the obtained colloid solution was taken and poured into hexane (10 mL) to precipitate the polymer. The obtained polymer did not show an emission spectrum, and the presence of ZnO nanoparticles could not be confirmed from TEM observation. It was confirmed by TEM observation that ZnO nanoparticles were present in the supernatant from which the polymer had been removed. When the remaining colloidal solution (3 mL) was stored at room temperature for 1 week, it became cloudy, and as a result of TEM observation, it was confirmed that ZnO nanoparticles were aggregated.

(Example 3)
The aqueous PDMA solution (1.5 mL) having an SH group at the end obtained in Production Example 2 was added to the 2-propanol solution (10 mL) of ZnO nanoparticles obtained in Production Example 6, and ultrasonic irradiation was performed at 30 ° C. For 2 hours. The obtained colloidal solution of polymer-modified ZnO nanoparticles was concentrated and then cast to obtain a transparent film of polymer-modified ZnO nanoparticles. This film was washed with hot water at 80 ° C. and observed by TEM, and it was confirmed that ZnO nanoparticles were dispersed without being aggregated.

Example 4
A PDMA aqueous solution (2 mL) having an SH group at the terminal obtained in Production Example 2 was dissolved in methanol (5 mL), and mixed with an ethanol solution (5 mL) of ZnO nanoparticles obtained in Production Example 7. After stirring at 50 ° C. for 4 hours, the obtained colloidal solution of polymer-modified ZnO nanoparticles was concentrated and cast to obtain a transparent film of polymer-modified ZnO nanoparticles. This film was washed with hot water at 80 ° C. and observed by TEM, and it was confirmed that ZnO nanoparticles were dispersed without being aggregated.

(Example 5)
PMMA (1 g) having an SH group at the end obtained in Production Example 3 was added to a toluene solution (5 mL) of Mn-doped ZnO nanoparticles obtained in Production Example 8, and ultrasonic irradiation was performed at 60 ° C. for 2 hours. . The obtained colloidal solution of polymer-modified ZnO nanoparticles was poured into methanol (50 mL) to precipitate the polymer-modified ZnO nanoparticles. The presence of dodecylamine was confirmed by GC analysis of the supernatant. This is because the dodecylamine protecting the surface of the ZnO nanoparticles was replaced with PMMA having an SH group at the terminal. Further, it was confirmed from the TEM analysis and emission spectrum analysis that the supernatant contained almost no Mn-doped ZnO nanoparticles. The polymer-modified ZnO nanoparticles were washed with methanol and cast using toluene (5 mL) to prepare a film. It was confirmed by TEM observation that the Mn-doped ZnO nanoparticles were dispersed without being aggregated.

(Comparative Example 2)
Commercially available PMMA (Mw 15000, Aldrich) (1 g) was added to a toluene solution (5 mL) of Mn-doped ZnO nanoparticles obtained in Production Example 8, and ultrasonic irradiation was performed at 60 ° C. for 2 hours. The resulting solution was poured into methanol (50 mL) to precipitate the polymer. In the GC analysis of the supernatant liquid, dodecylamine was not observed, but as a result of TEM analysis, many aggregated Mn-doped ZnO nanoparticles were confirmed. The polymer was washed with methanol and cast using toluene (5 mL) to prepare a film. It was confirmed by TEM observation that the number of Mn-doped ZnO nanoparticles contained in the polymer was extremely small. Furthermore, the Mn-doped ZnO nanoparticles in the polymer were agglomerated.

(Example 6)
PSt (1 g) having an SH group at the end obtained in Production Example 4 was added to a toluene solution (5 mL) of Mn-doped ZnO nanoparticles obtained in Production Example 8, and ultrasonic irradiation was performed at 60 ° C. for 2 hours. . The resulting solution was poured into methanol (50 mL) to precipitate the polymer. The presence of dodecylamine was confirmed by GC analysis of the supernatant. This is because the dodecylamine protecting the surface of the ZnO nanoparticles was replaced with PSt having an SH group at the terminal. Further, it was confirmed from the TEM analysis and emission spectrum analysis that the supernatant contained almost no Mn-doped ZnO nanoparticles. The polymer-modified ZnO nanoparticles were washed with methanol and cast using toluene (5 mL) to prepare a film. It was confirmed by TEM observation that the Mn-doped ZnO nanoparticles were dispersed without being aggregated.

(Comparative Example 3)
Commercially available PSt (Mw 4000, Aldrich) (1 g) was added to a toluene solution (5 mL) of Mn-doped ZnO nanoparticles obtained in Production Example 8, and ultrasonic irradiation was performed at 60 ° C. for 2 hours. The resulting solution was poured into methanol (50 mL) to precipitate the polymer. In the GC analysis of the supernatant liquid, dodecylamine was not observed, but as a result of TEM analysis, many aggregated Mn-doped ZnO nanoparticles were confirmed. The polymer was washed with methanol and cast using toluene (5 mL) to prepare a film. It was confirmed by TEM observation that the number of Mn-doped ZnO nanoparticles contained in the polymer was extremely small. Furthermore, the Mn-doped ZnO nanoparticles in the polymer were agglomerated.

(Example 7)
PBA (1 g) having an SH group at the end obtained in Production Example 5 was dissolved in acetone (5 mL), and added to an ethanol solution (5 mL) of ZnO nanoparticles obtained in Production Example 7. The obtained solution was irradiated with ultrasonic waves at room temperature for 2 hours, concentrated and dried under reduced pressure to obtain ZnO nanoparticles modified with PBA. 0.1 g of this polymer-modified nanoparticle was dissolved in 3 mL each of toluene, acetone, tetrahydrofuran, chloroform, ethanol to prepare a transparent colloidal solution. These transparent colloid solutions were stable even when stored at room temperature for 6 months or more, and no aggregation of ZnO nanoparticles was observed.

(Comparative Example 4)
When the 2-propanol solution (3 mL) of ZnO nanoparticles obtained in Production Example 6 was stored at room temperature, turbidity occurred in 5 days, and as a result of TEM observation, it was confirmed that ZnO nanoparticles were aggregated.

(Comparative Example 5)
When the ethanol solution (3 mL) of MnO nanoparticles obtained in Production Example 7 was stored at room temperature, turbidity occurred in one week, and as a result of TEM observation, it was confirmed that ZnO nanoparticles were aggregated.

(Comparative Example 6)
When the toluene solution (3 mL) of Mn-doped ZnO nanoparticles obtained in Production Example 8 was stored at room temperature, turbidity occurred in 15 days, and as a result of TEM observation, it was confirmed that Mn-doped ZnO nanoparticles were agglomerated. It was.

(Example 8)
Chem. Mater. With reference to the method of 2000, 12, 2268, ZnO nanoparticles surface-modified with PDMA having an SH group at the end were synthesized.

  Zinc acetate dihydrate (110 mg) was added to 2-propanol (80 mL) and stirred at 50 ° C. for 1 hour with vigorous stirring. 2-Propanol was added to bring the total volume of the solution to 920 mL and cooled to 0 ° C. This solution was divided into four equal parts as a stock solution.

  To one of the stock solutions, PDMA (1.8 g) having an SH group at the end obtained in Production Example 2 was added, and a methanol solution of NaOH (0.02 mol / L) (50 mL) while sonicating at room temperature. Was added dropwise over 2 hours. Furthermore, ultrasonic irradiation and stirring were continued for 2 hours at room temperature. As a result of TEM observation, it was confirmed that ZnO nanoparticles having a number average particle diameter of 2.5 nm were present without being aggregated. The transparent colloidal solution of ZnO nanoparticles surface-modified with PDMA thus obtained was stable even after storage for 6 months or more at room temperature, and no aggregation was observed.

(Comparative Example 7)
To one of the stock solutions of Example 8, commercially available polyvinylpyrrolidone (PVP) (Mw10000, Aldrich) (1.3 g) was added, and a methanol solution of NaOH (0.02 mol / L) (0.02 mol / L) with ultrasonic irradiation at room temperature ( 50 mL) was added dropwise over 2 hours. Furthermore, ultrasonic irradiation and stirring were continued for 2 hours at room temperature. As a result of TEM observation, it was confirmed that ZnO nanoparticles having a number average particle diameter of 3.1 nm were present without being aggregated. However, the transparent colloidal solution of ZnO nanoparticles surface-protected with PVP thus obtained has low stability, and when stored at room temperature for about 3 weeks, it becomes turbid and it was confirmed that ZnO nanoparticles are aggregated.

  The polymer-modified nanoparticles of the present invention are phosphors for display, photoelectric conversion elements, light-emitting diodes, wavelength conversion materials, ultraviolet shielding materials, dye-sensitized solar cells, as materials that stably express quantum effects without aggregation. It is useful as a fluorescent paint, fluorescent film, luminescent paint, luminescent film, diagnostic agent, trace component detection reagent, analytical reagent, drug delivery system, quantum transistor, quantum dot laser, light emitter for display, varistor, catalyst and the like.

Claims (11)

  Polymer modification obtained by surface-modifying metal oxide nanoparticles having a number average particle diameter of 100 nm or less using a polymer obtained by reversible addition / desorption chain transfer polymerization using a thiocarbonylthio compound as a chain transfer agent Nanoparticles.   The polymer-modified nanoparticles according to claim 1, wherein the polymer used for the surface modification is a polymer that is terminally SH-modified by a treating agent after reversible addition / desorption chain transfer polymerization using a thiocarbonylthio compound as a chain transfer agent. .   The polymer-modified nanoparticles according to claim 2, wherein the treatment agent is selected from the group consisting of a hydrogen-nitrogen bond-containing compound, a basic compound, and a reducing agent.   Polymers used for surface modification are (meth) acrylic acid esters, (meth) acrylamides, (meth) acrylic acid, styrene, sodium p-styrenesulfonate, (vinylbenzyl) trimethylammonium chloride, acrylonitrile, vinylpyrrolidone, vinylpyridine The polymer-modified nanoparticles according to any one of claims 1 to 3, wherein one or more monomers selected from the group consisting of vinyl acetate, vinyl chloride, maleic anhydride, and maleimide are polymerized.   The polymer-modified nanoparticles according to any one of claims 1 to 4, wherein the molecular weight distribution of the polymer used for the surface modification is 1.5 or less.   The polymer-modified nanoparticles according to any one of claims 1 to 5, wherein the number average particle diameter of the metal oxide nanoparticles is 10 nm or less.   The polymer-modified nanoparticles according to any one of claims 1 to 6, wherein the metal oxide nanoparticles are obtained by reacting an organometallic compound and an OH group-containing basic compound in a solvent.   The polymer-modified nanoparticles according to claim 7, wherein the OH group-containing basic compound is a compound selected from the group consisting of LiOH, NaOH, and KOH.   The organometallic compound is zinc acetate, zinc acetate dihydrate, zinc acetylacetonate hydrate, zinc benzoate, zinc citrate, zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate, zinc formate, zinc formate dihydrate. The polymer-modified nanoparticles according to any one of claims 7 and 8, which is a compound selected from the group consisting of zinc laurate and zinc salicylate trihydrate.   Metal oxide nanoparticles are Zn, Ti, Zr, Cr, Mo, W, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Cu, Ag, Cd, Al, Ga, In, Si, Ge The polymer-modified nanoparticles according to any one of claims 1 to 9, which are doped with an element selected from the group consisting of Sn, Pb, lanthanoids and actinoids.   A transparent colloid solution containing the polymer-modified nanoparticles according to any one of claims 1 to 10.