JP2008037884A - Metal nano-particle dispersion and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the dispersion of metal nano-particles having high preservation stability and excellent dispersion stability, and a method for producing the same. <P>SOLUTION: This dispersion of metal nano-particles is provided by containing the dispersion of (X) a polymer compound having (a) a branched polyalkylene imine chain, (b) a hydrophilic segment and (c) a hydrophobic segment, and (Y) metal nano-particles. The method for producing the dispersion of metal nano-particles is provided by dispersing the polymer compound having (a) the branched polyalkylene imine chain, (b) hydrophilic segment and (c) hydrophobic segment with a solvent, then adding a metal salt or metal ion solution, reducing the metal ion to make the metal nano-particles. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a metal nanoparticle dispersion in which a metal nanoparticle is contained in a dispersion formed by a polymer compound containing a branched polyalkyleneimine chain, a hydrophilic segment, and a hydrophobic segment in a solvent, and The present invention relates to a method for producing a metal nanoparticle dispersion.

  Metal nanoparticles are nanoparticles having a particle size of 1 to several hundred nanometers, and their specific surface area is remarkably large. Therefore, they are attracting attention from many fields, and include catalysts, electronic materials, magnetic materials, optical materials, various sensors, colors Application to materials, medical examinations, etc. is expected. However, when the metal is reduced to a nano size, the surface energy increases, so that a melting point drop occurs on the particle surface. As a result, the metal nanoparticles tend to be fused with each other, resulting in poor storage stability. In order to stabilize the metal nanoparticles, it is necessary to protect them with a protective agent in order to prevent the fusion.

  As a method for producing metal nanoparticles, there are a solution method, a gas phase method, and the like. In any case, the use of a protective agent is indispensable as described above, and various protective agents have been proposed. As protective agents, for example, proteins such as gelatin and albumin and water-soluble polymers such as polyvinyl alcohol and polyvinyl pyrrolidone are generally known to have higher protective power than low molecular weight surfactants. (For example, refer to Patent Document 1). However, since metal nanoparticles using a water-soluble polymer as a protective agent tend to aggregate between the protective agents, the resulting metal nanoparticles often also aggregate, which is a fundamental solution for storage stability. It will not be. Also in the above-mentioned patent document 1, after protecting with a protective agent, by using a complicated means of removing the solvent and re-dispersing in a desired solvent when used as a metal powder, there is a problem of storage stability. It is a solution. In general, a protective agent is one that forms metal nanoparticles by physically or chemically adsorbing or bonding to the surface of the metal, but the water-soluble polymer is poor in binding force with the metal surface, so There is also a drawback that the nanoparticles cannot be protected stably.

  As an attempt to stably protect metal nanoparticles, for example, a method using a polymer aggregate using a triblock copolymer of polydiethylaminoethyl methacrylate-polyglycerol monomethacrylate-polyethylene glycol (PDEA-PGMA-PEG) is disclosed. (See, for example, Non-Patent Document 1). The polymer aggregate of the triblock copolymer has a PDEA chain as a core part and a PEG chain as a shell layer responsible for dispersion stability in water, and an intermediate layer composed of PGMA chains in the middle. The aggregate is stabilized by incorporating a metal into the core portion by an amino group in the PDEA chain and maintaining the shape of the aggregate by mutual cross-linking of the PGMA chains forming an intermediate layer around the core portion. However, since the PDEA chain that forms the core of the aggregate is a hydrophilic polymer chain, the aggregate has a poor association force in water and has a factor that makes the aggregate shape unstable. Further, in order to incorporate metal into the core portion, the cross-linking density of the intermediate layer substantially maintaining the aggregate shape cannot be increased, and there is a limit to improving the storage stability of the aggregate. .

  As an example of a dispersion having a stable core, there is a report using a polymer obtained by grafting an amino group-containing polymer such as polyallylamine or poly (aminoethyl methacrylate hydrochloride) on the surface of polystyrene particles or polymethyl methacrylate particles ( For example, refer nonpatent literature 2, 3, and 4.). However, the dispersion formed by the polymer mainly incorporates the metal into the shell layer that contributes to the dispersion stability in the solvent, so that the dispersion of the shell layer due to the reduction and incorporation of the metal changes the dispersion. Stability is insufficient and further improvement is required.

JP-A-8-027307 S. Liu, J .; V. M.M. Weaver, M .; Save, S.M. P. Armes, Langmuir, 2002, 18, 8350. J. et al. H. Youk, Polymer, 2003, 44, 5053. G. Sharma, M .; Ballauff, Macromolecular Rapid Communications, 2004, 25, 547.

  The problem to be solved by the present invention is to provide a metal nanoparticle dispersion having high storage stability and excellent dispersion stability and a method for producing the same.

  As a result of intensive studies to solve the above problems, the inventors of the present invention have made it possible to lengthen the associating force of segments having high dispersibility, segments capable of fixing or reducing metal nanoparticles, and aggregates. When a polymer compound having three segments that contribute to holding is used, a stable dispersion can be obtained in a solvent, and the metal nanoparticles can be stably present in the dispersion and have the above performance. The inventors have found that a metal nanoparticle dispersion can be obtained, and have completed the present invention.

  That is, the present invention provides a metal in a dispersion formed by a polymer compound (X) having a branched polyalkyleneimine chain (a), a hydrophilic segment (b), and a hydrophobic segment (c) in a solvent. The present invention provides a metal nanoparticle dispersion characterized by containing nanoparticles (Y).

  Further, in the present invention, a polymer compound having a branched polyalkyleneimine chain, a hydrophilic segment, and a hydrophobic segment is dispersed in a solvent, and then a metal salt or a metal ion solution is added to form a metal ion. The present invention also provides a method for producing a metal nanoparticle dispersion, characterized in that the metal is stabilized as nanoparticles.

  The metal nanoparticle dispersion of the present invention is capable of reducing metal ions by the strong reducing ability, coordination bonding force and electrostatic interaction of the branched polyalkyleneimine chain, and immobilizing them in the dispersion as nanoparticles. Is possible. Even if there is a change in the morphology of the dispersion due to the shrinkage of the branched polyalkyleneimine chain or the like due to the function of the polyalkyleneimine, the hydrophilic segment and hydrophobicity in the polymer compound forming the dispersion The high-affinity segment expresses an excellent self-organization ability due to a high affinity with the solvent and a strong associating force due to the interaction between the segments, so that the dispersion stability as a dispersion is not impaired, and in the solvent A stable dispersion state can be maintained for a long time.

  The metal nanoparticle dispersion of the present invention can hold one metal nanoparticle in one dispersion, but can also immobilize a plurality of metal nanoparticles, The amount can be easily adjusted. Therefore, the metal nanoparticle dispersion of the present invention has characteristics as metal nanoparticles such as a large specific surface area, high surface energy, and plasmon absorption, and further, the dispersion stability and storage stability of the self-assembled polymer dispersion. It is possible to efficiently develop properties such as properties, and has various chemical, electrical, and magnetic performances required for conductive pastes, etc., and in various fields such as catalysts, electronic materials, magnetic materials, optical materials, various types Applications to sensors, color materials, medical examinations, etc. are possible.

  In the metal nanoparticle dispersion of the present invention, a polymer compound (X) containing a branched polyalkyleneimine chain (a), a hydrophilic segment (b), and a hydrophobic segment (c) is formed in a solvent. In this dispersion, the metal nanoparticles (Y) are contained.

  In the branched polyalkyleneimine chain (a) constituting the polymer compound (X) used in the present invention, the alkyleneimine unit in the chain can be coordinated with a metal or a metal ion. It is a polymer chain that can be immobilized as particles. The structure includes a secondary amine alkyleneimine unit as a main repeating unit and further includes a branched structure. The structure of the branched portion is not particularly limited, and a commercially available branched polyalkyleneimine is branched by a tertiary amine, and is used as it is as a raw material for the polymer compound (X) used in the present invention. Can be used as

  When the dispersion of the present invention is obtained by the method for producing a metal nanoparticle dispersion described below, the particle size is not limited to the molecular weight of the polymer compound (X) used and the degree of branching of the branched polyalkyleneimine chain (a). Depending on the structure and composition ratio of each component constituting the polymer compound (X), that is, the branched polyalkyleneimine chain (a), the hydrophilic segment (b) described later, and the hydrophobic segment (c) described later. to be influenced. In the case of the branched polyalkyleneimine chain (a) having the same molecular weight, the particle size of the resulting dispersion is large when the degree of branching is small, and the particle size tends to decrease as the degree of branching increases.

  From the viewpoint of obtaining a metal nanoparticle dispersion having a desirable particle size capable of maintaining stable dispersibility, the branching degree is expressed in a range of 1 to 49/100 in terms of (tertiary amine) / (all amines). In view of industrial production, availability, etc., a more preferable range is 15 to 40/100.

  The degree of polymerization of the branched polyalkyleneimine chain (a) is not particularly limited, but if it is too low, the amount of metal nanoparticles contained in the dispersion of the polymer compound (X) and its stable If the retention is insufficient, and the polymer compound (X) is too high, the polymer compound (X) becomes a huge aggregate, which impedes storage stability. Therefore, in order to obtain a metal nanoparticle dispersion having a better ability to immobilize metal nanoparticles in the obtained metal nanoparticle dispersion and to prevent the dispersion from becoming too large, the branched polymer is obtained. The degree of polymerization of the alkyleneimine chain (a) is usually in the range of 1 to 10,000, preferably in the range of 3 to 3,000, and more preferably in the range of 5 to 1,000.

  The branched polyalkyleneimine chain (a) can be used without particular limitation as long as it is generally commercially available or can be synthesized, but from the viewpoint of industrial availability, polyethyleneimine The chain is preferably a polypropyleneimine chain.

  The hydrophilic segment (b) constituting the polymer compound (X) used in the present invention has a high affinity for the solvent when the polymer compound (X) is dispersed in a hydrophilic solvent such as water. And a segment that maintains dispersion stability when a dispersion is formed. Further, when dispersed in a hydrophobic solvent, the hydrophilic segment (b) has a role of forming a core of the dispersion due to a strong associative force within the molecule or between the molecules. The degree of polymerization of the hydrophilic segment (b) is not particularly limited, but when dispersed in a hydrophilic solvent, if the degree of polymerization is too low, the dispersion stability is deteriorated, and if too high, the dispersions are dispersed. There is a possibility of aggregation, and when dispersed in a hydrophobic solvent, if the degree of polymerization is too low, the associating power of the dispersion becomes poor, and if it is too high, the affinity with the solvent cannot be maintained. From these viewpoints, the degree of polymerization of the hydrophilic segment (b) is usually 1 to 10,000, preferably 3 to 3,000, and 5 to 1,000 from the viewpoint of ease of production. It is more preferable that Furthermore, the polymerization degree in the case of a polyoxyalkylene chain is particularly preferably 5 to 500.

  The hydrophilic segment (b) can be used without particular limitation as long as it is generally composed of a hydrophilic polymer chain that is commercially available or can be synthesized. In particular, in a hydrophilic solvent, a nonionic polymer is preferable because a dispersion having excellent stability can be obtained.

  Examples of the hydrophilic segment (b) include polyoxyalkylene chains such as polyoxyethylene chains and polyoxypropylene chains, polymer chains composed of polyvinyl alcohols such as polyvinyl alcohol and partially saponified polyvinyl alcohol, polyhydroxyethyl acrylate, Polymer chains composed of water-soluble poly (meth) acrylic esters such as hydroxyethyl methacrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, polyacetylethyleneimine, polyacetylpropyleneimine, polypropionylethyleneimine, polypropionylpropyleneimine Polyacylalkyleneimine chains having hydrophilic substituents such as polyacrylamide, polyisopropylacrylamide, polyvinyl pyrrolidone, etc. Examples thereof include polymer chains composed of acrylamides. Among these, polyoxyalkylene chains are preferable because a dispersion having particularly excellent stability is obtained and industrial availability is easy. .

  When the polymer compound (X) is dispersed in a hydrophilic solvent such as water, the hydrophobic segment (c) constituting the polymer compound (X) used in the present invention is intermolecular or intermolecularly interlinked. Due to the strong associative force, the core of the dispersion is formed and has a role of forming a stable dispersion. Further, when dispersed in a hydrophobic solvent, the segment has a high affinity with the solvent and retains the dispersion stability when a dispersion is formed.

  The hydrophobic segment (c) can be used without particular limitation as long as it is composed of residues of hydrophobic compounds that are generally commercially available or can be synthesized. For example, polystyrenes such as polystyrene, polymethylstyrene, polychloromethylstyrene, polybromomethylstyrene, polyacrylic acid methyl ester, polymethacrylic acid methyl ester, polyacrylic acid 2-ethylhexyl ester, polymethacrylic acid 2-ethylhexyl ester, etc. Water-insoluble poly (meth) acrylic acid esters, polybenzoylethyleneimine, polybenzoylpropyleneimine, poly (meth) acryloylethyleneimine, poly (meth) acryloylpropyleneimine, poly [N- {3- (perfluoro Octyl) propionyl} ethyleneimine], poly [N- {3- (perfluorooctyl) propionyl} propyleneimine] and the like polymer residues of polyacylalkyleneimines having a hydrophobic substituent, Epoxy resins, polyurethanes, include such residues of the resin and polycarbonate, also a residue of a single compound or a residue of a compound obtained by previously reacting the two or more different compounds.

  The epoxy resin is not particularly limited as long as it is commercially available or can be synthesized. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, naphthalene type tetrafunctional epoxy resin, tetramethylbiphenyl type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, Bisphenol A novolac type epoxy resin, triphenylmethane type epoxy resin, tetraphenylethane type epoxy resin, dicyclopentadiene-phenol addition reaction type epoxy resin, phenol aralkyl type epoxy resin, naphthol novolak type epoxy resin, naphthol aralkyl type epoxy resin, Naphthol-phenol co-condensed novolak epoxy resin, Naphthol-cresol co-condensed novolac epoxy resin, Aromatic hydrocarbon form Aldehyde resin modified phenol resin type epoxy resin, a biphenyl novolak type epoxy resin, a xanthene type epoxy resins described in JP-2003-201333, may be used alone, or may be a mixture of two or more. Among these, when the obtained metal nanoparticle dispersion is used as a conductive paste, it is preferably a residue of a bisphenol A type epoxy resin from the viewpoint of excellent adhesion to a substrate, and the like in a hydrophilic solvent. From the viewpoint of obtaining a dispersion having a strong associative strength and excellent dispersion stability and storage stability, it is preferably a residue of a trifunctional or higher functional epoxy resin such as a naphthalene type tetrafunctional epoxy resin. In addition, these epoxy resins may be used as raw materials for the polymer compound (X) as they are, and may be modified with various modifications according to the structure of the target polymer compound (X). good.

  The polyurethane can be used without particular limitation as long as it is commercially available or can be synthesized. In general, polyurethane is a polymer obtained by addition reaction of polyol and polyisocyanate. Examples of the polyol include propylene glycol, neopentyl glycol, polypropylene glycol, polytetramethylene ether glycol, polyester polyol, polycaprolactone polyol, polycarbonate diol, bisphenol A, bisphenol F, 4,4′-dihydroxybiphenyl, 3, 3 ′, 5,5′-tetramethylbiphenyl-4,4′-diol, phenol novolak, cresol novolak, propanediol, butanediol, pentanediol, n-hexanediol, cyclohexanediol, methylpentanediol, polybutadiene dipolyol, Modified from trimethylolpropane, dihydroxybenzene, difunctional or higher functional glycidyl group, and the above epoxy resin Mentioned compounds, etc., may be used in either singly or in combination.

  Examples of the polyisocyanate include diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, bis (isocyanate methyl) cyclohexane, hexamethylene diisocyanate, 1,5-naphthylene diisocyanate, tetramethylxylene diisocyanate, isophorone diisocyanate, hydrogenated xylylene. Examples include diisocyanate, dicyclohexylmethane diisocyanate, hexamethine diisocyanate, dimer acid diisocyanate, norbornene diisocyanate, and trimethylhexamethylene diisocyanate. These may be used alone or in admixture of two or more.

  Among these, when the obtained metal nanoparticle dispersion is used as a conductive paste, from the viewpoint of excellent adhesion to various substrates composed of inorganic materials or hybrid materials, the polyol may be polypropylene. Glycols, bisphenol A type epoxy resin-modified polyols and the like are preferable, and polyisocyanates are preferably hexamethylene diisocyanate, bis (isocyanate methyl) cyclohexane, and most preferably polyurethane obtained by combining these preferable raw materials. In addition, these polyurethanes may be used as raw materials for the polymer compound (X) as they are, and may further be modified according to the structure of the target polymer compound (X). .

  The polycarbonates are not particularly limited as long as they are commercially available or can be synthesized. In general, polycarbonate is a polymer produced from a condensation reaction between bisphenol A and phosgene, diphenyl carbonate, or the like. Polycarbonate is a typical example of the polycarbonates, but various carbonate-based polymers that can be produced using various raw materials exemplified by polyols that are raw materials of the polyurethanes instead of bisphenol A, which is a raw material of polycarbonates, are also available. Examples of polycarbonates can be mentioned.

  Among these, when the obtained metal nanoparticle dispersion is used as a conductive paste, polycarbonate is preferable from the viewpoint of excellent adhesion to various substrates such as a polycarbonate substrate. In addition, these polycarbonates may be used as raw materials for the polymer compound (X) as they are, and may further be modified according to the structure of the target polymer compound (X). good.

  Among the hydrophobic segments (c) listed above, one or more compounds selected from polystyrene, poly (meth) acrylic acid ester, epoxy resin, polyurethane, polycarbonate, and polyacylalkyleneimine having a hydrophobic substituent. Residues are comprehensively determined not only from the industrial availability and ease of handling of each compound used as a raw material, but also from the high hydrophobic associative power of the polymer compound (X). It is a preferable hydrophobic segment, and is particularly excellent in the industrial production method of the polymer compound (X), and from the viewpoint of cost, availability, etc., polystyrene, poly (meth) methyl acrylate, epoxy resins, polyurethanes. It is more preferably a residue, and most preferably a residue of epoxy resins.

  Further, the degree of polymerization of the hydrophobic segment (c) is not particularly limited, but when dispersed in a hydrophilic solvent, the dispersion stability deteriorates if it is too low, and the dispersion aggregates if it is too high. In the case of dispersing in a hydrophobic solvent, if the dispersion is too low, the dispersibility of the dispersion becomes poor, and if it is too high, the affinity with the solvent cannot be maintained. From these viewpoints, the polymerization degree of the hydrophobic segment (c) is usually 1 to 10,000, such as polystyrenes, poly (meth) acrylic acid esters, polyacylalkyleneimines having a hydrophobic substituent, and the like. In some cases, it is preferably 3 to 3,000, more preferably 10 to 1,000. Moreover, when it consists of resin residues, such as epoxy resins, polyurethanes, and polycarbonates, the degree of polymerization is usually 1-50, preferably 1-30, particularly 1-20. Is preferred.

  The polymer compound (X) used in the present invention is a compound in which the aforementioned branched polyalkyleneimine chain (a), the hydrophilic segment (b), and the hydrophobic segment (c) are bonded. The hydrophilic segment (b) and the hydrophobic segment (c) have a structure in which they are bonded to the branched polyalkyleneimine chain (a), and the metal is immobilized in the dispersion as metal nanoparticles, And has the ability to form a dispersion having high dispersion stability and storage stability.

  The production method of the polymer compound (X) used in the present invention is not particularly limited, but the following method is used because the polymer compound (X) as designed can be easily synthesized. preferable.

  As described above, commercially available or synthesized branched polyalkyleneimine chains can be suitably used.

  The synthesis of the branched polyalkyleneimine chain may be carried out by various methods, and is not particularly limited, but generally includes a method of ring-opening polymerization of ethyleneimine using an acid catalyst. Since the terminal of the branched polyethyleneimine is a primary amine, if the hydrophilic segment and the hydrophobic segment have a functional group that reacts with the primary amine, by reacting sequentially or simultaneously, A polymer compound that can be used in the present invention can be synthesized. The functional group that reacts with the primary amine is not particularly limited. For example, aldehyde group, carboxyl group, isocyanate group, tosyl group, epoxy group, glycidyl group, isothiocyanate group, halogen, acid chloride, sulfonic acid Examples include chloride. Of these, a carboxyl group, an isocyanate group, a tosyl group, an epoxy group, and a glycidyl group are advantageous in terms of production, such as reactivity and ease of handling, and are preferred functional groups.

  In addition, the functional group that can react with the primary amine is not limited to the functional group that directly reacts with the primary amine, but may be any functional group that can react with the primary amine by performing various treatments. May be reacted with a polyethyleneimine chain by a technique such as glycidylation. Furthermore, after the primary amine of the branched polyalkyleneamine chain is converted to other functional groups capable of reacting with the functional group of the hydrophilic segment or the hydrophobic segment, these are reacted to increase the functionality. It is also possible to synthesize the molecular compound (X).

  Furthermore, a compound obtained by reacting a branched polyalkyleneimine chain with a nonionic hydrophilic polymer in advance is dissolved or dispersed in an aqueous medium, where a radical initiator and a hydrophobic segment are derived. An aqueous dispersion of the polymer compound (X) used in the present invention can be obtained by adding a radical polymerizable monomer and performing radical polymerization. This technique is based on the radical starting point generated in the amino group due to the interaction between the radical initiator such as peroxide and the amino group, or the chain generated by the radical generated from the radical initiator to the amino group. Hydrophobic segments are introduced into a compound obtained by reacting a branched polyalkyleneimine chain with a nonionic hydrophilic polymer by polymerizing the radical polymerizable monomer from the radical starting point generated in the reaction. Examples of radical polymerizable monomers that can be used here include styrenes such as styrene, 2-methylstyrene, and 3-methylstyrene, methyl (meth) acrylate, ethyl (meth) acrylate, and (meth) acrylic acid. (Meth) acrylic acid esters such as butyl may be mentioned, and styrene and methyl (meth) acrylate are preferably used from the viewpoints of industrial availability and ease of handling.

A typical synthesis example of the polymer compound (X) will be described.
(I) A commercially available product is used as the branched polyalkyleneimine, and a tosyl derivative of polyethylene glycol monomethyl ether is used as the hydrophilic polymer. The hydrophilic polymer can be obtained, for example, by reacting polyethylene glycol monomethyl ether and tosyl chloride in a polar solvent in the presence of pyridine. As the hydrophobic polymer, an epoxy resin having an epoxy group at the terminal is used. In the case of this combination, first, polyethyleneimine is dissolved in a polar solvent and reacted with a tosyl derivative of polyethylene glycol monomethyl ether at 100 ° C. in the presence of an alkali such as potassium carbonate to obtain a compound having polyethylene glycol and a polyethyleneimine structure. A polymer compound having a polyethylene glycol-polyethyleneimine-epoxy resin structure can be obtained by synthesizing and then adding an epoxy resin in a mixed solvent of acetone and methanol and reacting at 60 ° C.

  (II) A branched polyalkyleneimine is a commercially available product, and as a hydrophilic polymer, a tosyl derivative of polyethylene glycol monomethyl ether obtained in the same manner as in (I) is used. As the hydrophobic polymer, polystyrene having one end brominated synthesized by atom transfer radical polymerization (ATRP) is used. The polystyrene can be synthesized by, for example, living radical polymerization of a styrene monomer in a toluene solvent in the presence of bipyridine, copper bromide, and 1-bromoethylbenzene. In the case of this combination, first, one-end brominated polystyrene is dissolved in a polar solvent and treated with an alkali such as sodium hydroxide to obtain a polystyrene having one end hydroxylated. Furthermore, tosyl chloride is reacted in the presence of pyridine in a polar solvent to give one-terminal tosylated polystyrene. By reacting this with a compound having polyethylene glycol and a polyethyleneimine structure in the same manner as in (I) at 100 ° C. in the presence of an alkali such as potassium carbonate in a polar solvent, the structure of polyethylene glycol-polyethyleneimine-polystyrene is obtained. The high molecular compound which has can be obtained.

  Ratio of the degree of polymerization of the polymer constituting the chain of each component of the branched polyalkyleneimine chain (a), hydrophilic segment (b), and hydrophobic segment (c) in the polymer compound (X) used in the present invention ( Although it does not specifically limit as a) :( b) :( c), From the point which is excellent in the associative force, dispersion stability, and storage stability of the obtained metal nanoparticle dispersion, it is usually 5,000: It is in the range of 5 to 5,000,000: 1 to 5,000,000, and particularly preferably 50,000: 25 to 400,000: 5 to 1,000,000. Further, when the degree of polymerization of the branched polyalkyleneimine chain is 5,000, when a polyoxyalkylene chain is used as the hydrophilic segment (b) as a preferred example, the range of the ratio is more preferably 25 to 200,000, and When polystyrenes, poly (meth) acrylic acid esters, polyacylalkyleneimines having a hydrophobic substituent, and the like are used for the hydrophobic segment (c), the range of the ratio is more preferably 15 to 1,000,000. When a compound comprising a residue of a resin such as epoxy resins, polyurethane or polycarbonate is used, the range of the ratio is more preferably 5 to 20,000.

  In the polymer compound (X) used in the present invention, apart from the branched polyalkyleneimine chain (a) capable of stably presenting metal nanoparticles, the compound (X) forms an aggregate in a solvent. When doing, it has the hydrophilic segment (b) and hydrophobic segment (c) which form a core part or a shell part. As described above, the hydrophilic segment (b) shows a strong associating force in a hydrophobic solvent, shows a high affinity with the solvent in the hydrophilic solvent, and the hydrophobic segment (c) in the hydrophilic solvent. It exhibits a strong associative force and exhibits a high affinity with a solvent in a hydrophobic solvent. Furthermore, when the hydrophobic segment (c) has an aromatic ring, the π electrons of the aromatic ring interact with the metal nanoparticle (Y), and further stabilize the metal nanoparticle (Y). It is thought that it contributes to this.

  In the present invention, when the metal nanoparticle dispersion is formed by using the compound (X) having such a metal-containing part, core-forming part and shell-forming part individually in the structure, In this case, there is no reduction in the associating force between the segments forming the core portion and shrinkage of the segments forming the shell portion, and the stability of the dispersion is not hindered by containing metal nanoparticles. Therefore, the metal nanoparticle dispersion of the present invention has a core part associated by a strong associating force and a shell part exhibiting excellent dispersion stability in a solvent, and has excellent storage stability in various solvents. It is.

  The metal species of the metal nanoparticles (Y) constituting the metal nanoparticle dispersion of the present invention are not limited as long as the metal or ion can coordinate with the branched polyalkyleneimine chain (a), Metal species such as transition metal-based metal compounds can be used. Of these, ionic transition metals are preferable, and transition metals such as copper, silver, gold, nickel, palladium, platinum, and cobalt are more preferable. The metal nanoparticles (Y) constituting the metal nanoparticle dispersion may be one type or two or more types. Among the exemplified transition metals, silver, gold, palladium, and platinum are particularly preferable because the metal ions are spontaneously reduced at room temperature or in a heated state after coordination with polyethyleneimine. Among them, silver, gold, and platinum are the most preferred transition metals in terms of ease of reduction reaction and ease of handling.

  The content of the metal nanoparticles (Y) in the metal nanoparticle dispersion of the present invention is not particularly limited, but if the content is too small, the characteristics of the metal nanoparticles in the dispersion are less likely to appear, If the amount is too large, the relative weight of the metal nanoparticles in the dispersion increases, and the viewpoint that the metal nanoparticle dispersion is expected to settle due to the balance between the relative weight and the dispersion holding power of the dispersion is high. From the viewpoint of reducing ability and coordination ability due to the alkyleneimine unit in the molecular compound (X), the content of the metal nanoparticles (Y) is the total nitrogen forming the branched polyalkyleneimine chain (a). When the number of atoms is 100 mol, the metal nanoparticles (Y) are usually in the range of 1 to 20,000 mol, preferably in the range of 1 to 10,000 mol, particularly in the production method described later. When when used in combination reducing agent 50～7,000Mol, not use the reducing agent is preferably 5～70Mol.

  The particle diameter of the metal nanoparticles (Y) constituting the metal nanoparticle dispersion of the present invention is not particularly limited, but in order for the metal nanoparticle dispersion to have higher dispersion stability, The particle diameter of the metal nanoparticles (Y) constituting the metal nanoparticle dispersion of the invention is preferably 1 to 50 nm, more preferably 5 to 30 nm.

  In general, metal particles in a size region of several tens of nm have characteristic optical absorption caused by surface plasmon excitation depending on the metal species. Therefore, by measuring the plasmon absorption of the dispersion obtained in the present invention, it is possible to confirm that the metal is present as fine particles of nanometer order in the dispersion. It is also possible to observe the average particle size, distribution width, and the like in a TEM (transmission electron microscope) photograph of a film obtained by casting the body.

  In the method for producing a metal nanoparticle dispersion of the present invention, a metal salt or a metal ion solution is added to a medium in which a compound having a branched polyalkyleneimine chain, a hydrophilic segment, and a hydrophobic segment is dispersed. The metal ions are reduced and stabilized as metal nanoparticles. The metal nanoparticle dispersion produced in this way is excellent in dispersion stability and storage characteristics, and has the ability as various metal-containing functional dispersions such as color development, catalyst, and electrical function of the metal nanoparticles. ing.

  The polymer compound having a branched polyalkyleneimine chain, a hydrophilic segment, and a hydrophobic segment, which is used in the method for producing a metal nanoparticle dispersion of the present invention, is prepared from the aforementioned raw materials by the above-described method. The compound forms a dispersion according to the medium in various media such as water, a hydrophilic solvent, and a hydrophobic solvent. What can be used as the medium is not limited, and the dispersion may be either an O / W system or a W / O system. Depending on the purpose of use of the resulting metal nanoparticle dispersion, a hydrophilic solvent, a hydrophobic solvent, a mixed solvent thereof, or a mixed solvent in combination with other solvents as described later can be selected and used. When a mixed solvent is used, the hydrophilic solvent is increased when the mixing ratio is O / W, and the hydrophobic solvent is increased when W / O. Since the mixing ratio varies depending on the type of polymer compound used, it cannot be generally limited. However, as an example of a general guideline, a hydrophilic solvent having a capacity of 5 times or more that of a hydrophobic solvent in the case of an O / W system. In the case of the W / O system, it is preferable to use a hydrophobic solvent having a capacity 5 times or more that of the hydrophilic solvent.

  Examples of the hydrophilic solvent include methanol, ethanol, isopropyl alcohol, tetrahydrofuran, acetone, dimethylacetamide, dimethylformamide, ethylene glycol, propylene glycol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol dimethyl ether, propylene glycol dimethyl ether, dimethyl Examples thereof include sulfone oxide, dioxirane, N-methylpyrrolidone and the like, and they may be used alone or in admixture of two or more.

  Examples of the hydrophobic solvent include hexane, cyclohexane, ethyl acetate, butanol, methylene chloride, chloroform, chlorobenzene, nitrobenzene, methoxybenzene, toluene, xylene, and the like, which may be used alone or in combination of two or more. good.

  Examples of other solvents that can be used by mixing with a hydrophilic solvent or a hydrophobic solvent include ethyl acetate, propyl acetate, butyl acetate, isobutyl acetate, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, and the like. The metal nanoparticle dispersion obtained may be appropriately selected and used depending on the intended use.

  A method for preparing a dispersion by dispersing a polymer compound in a medium is not particularly limited, and it can be easily obtained by standing at room temperature or stirring, but if necessary, Then, ultrasonic treatment, overheat treatment, or the like may be performed. Further, when the familiarity with the medium is low due to the crystallinity of the polymer compound, etc., for example, the polymer compound may be dissolved or swollen with a small amount of a good solvent and then dispersed in the target medium. . At this time, it is more effective to perform ultrasonic treatment or overheat treatment.

  When a hydrophilic solvent and a hydrophobic solvent are mixed and used, the mixing method and mixing order are not particularly limited, and various methods may be used. Since the affinity and dispersibility with various solvents may vary depending on the type and composition of the polymer compound used, the solvent mixing ratio, mixing order, mixing method, mixing conditions, etc. are appropriately selected according to the purpose. It is preferable to do.

  The metals used in the method for producing a metal nanoparticle dispersion of the present invention are as described above. When actually used as a raw material, a metal salt or an ionic solution is used. The metal ion that can be used here may be a water-soluble metal compound, such as a salt of a metal cation and an acid group anion, or a metal contained in an anion of an acid group, and the like. Metal ions having a metal species such as metal can be preferably used.

The transition metal ion may be a transition metal cation (M ^{n +} ), an acid group anion (MO _x ⁿ⁻ ) composed of a bond with oxygen, or an anion (ML _x ) composed of a halogen bond. ^{Even in the case of n-} ), it can be suitably coordinated in a complex state. In the present specification, the transition metal refers to Sc, Y in Group 3 of the periodic table, and transition metal elements in Groups 4 to 12 in the 4th to 6th periods.

Examples of transition metal cations include the following transition metal cations (M ^{n +} ), such as monovalent, divalent, trivalent, or tetravalent cations such as Cr, Co, Ni, Cu, Pd, Ag, Pt, and Au. Is mentioned. The counter anion of these metal cations may be Cl, NO ₃ , SO ₄ , or an organic anion of carboxylic acids. However, it is preferable to prepare a complex of Ag, Au, Pt or the like that is easily reduced by the polyethyleneimine skeleton by suppressing the reduction reaction, for example, by adjusting the pH to an acidic condition.

Further, anions containing the following metals (ML _x ⁿ⁻ ), such as AgNO ₃ , AuCl ₄ , PtCl ₄ , and CuF ₆ , are also preferably coordinated in a complex state. Can be made.

  Among these metal ions, as described above, in particular, metal ions of silver, gold, palladium, and platinum are coordinated to polyethyleneimine, and then spontaneously reduced at room temperature or in a heated state, thereby producing nonionic metal nanoparticles. It is preferable because it is converted to.

  Moreover, it is also possible to make 2 or more types of metal species to contain. In this case, when various kinds of metal salts or ions are added simultaneously or separately, various kinds of metal ions undergo a reduction reaction within the dispersion to produce various kinds of metal particles. Can be obtained.

  When using a metal that does not reduce spontaneously, or a metal that is not sufficiently reduced spontaneously, or when you want to incorporate a large amount of metal into the dispersion, reduce the metal ion with a reducing agent. A metal nanoparticle dispersion can also be formed by passing through the process of making it.

  Various reducing agents can be used as the reducing agent, and the reducing agent is not particularly limited. It is preferable to select the reducing agent depending on the intended use of the resulting metal nanoparticle dispersion, the metal species to be contained, and the like. . Examples of reducing agents that can be used include boron compounds such as hydrogen, sodium borohydride, ammonium borohydride, alcohols such as methanol, ethanol, propanol, isopropyl alcohol, ethylene glycol, and propylene glycol, formaldehyde, acetaldehyde, Aldehydes such as propionaldehyde, acids such as ascorbic acid, citric acid, sodium citrate, propylamine, butylamine, diethylamine, dipropylamine, dimethylethylamine, triethylamine, ethylenediamine, triethylenetetramine, methylaminoethanol, dimethylaminoethanol, Examples include amines such as triethanolamine, and hydrazines such as hydrazine and hydrazine carbonate. Among these, sodium borohydride, ascorbic acid, sodium citrate, methylaminoethanol, dimethylaminoethanol and the like are more preferable from the viewpoint of industrial availability and handling.

  In the production method of the present invention, the use ratio of the polymer compound to the metal salt or ionic solution is not particularly limited, but all the nitrogen atoms forming the branched polyalkyleneimine chain of the polymer compound When the number is 100 mol, the metal is usually in the range of 1 to 20,000 mol, and preferably in the range of 1 to 10,000 mol, especially 50 to 7,000 mol when reducing agent is used in combination. When no agent is used in combination, the amount is preferably 5 to 70 mol.

  In the method for producing a metal nanoparticle dispersion of the present invention, the method of mixing the medium in which the polymer compound is dispersed with the metal salt or ionic solution is not particularly limited. A method in which a metal salt or ionic solution is added to a medium in which is dispersed can be used, or vice versa. A mixing method such as stirring is not particularly limited.

  Further, when a reducing agent is used in combination, the addition method is not limited. For example, the reducing agent can be mixed as it is or dissolved or dispersed in an aqueous solution or other solvent. Also, the order of adding the reducing agent is not limited. Even if the reducing agent is added to the polymer compound dispersion in advance, the reducing agent is added at the same time when the metal salt or ionic solution is mixed. Alternatively, a method of mixing a reducing agent after mixing several days or weeks after mixing a dispersion of a polymer compound and a metal salt or ionic solution may be used.

  When the metal salt or ionic solution thereof used in the production method of the present invention is added to the medium in which the polymer compound is dispersed, it is prepared as it is or in an aqueous solution regardless of the O / W system or W / O system. To add. As described above, metal ions such as silver, gold, palladium and platinum are coordinated to the alkyleneimine unit in the copolymer and then spontaneously reduced at room temperature or in a heated state. The metal nanoparticle dispersion can be obtained by standing or stirring. Even when a reducing agent is used as necessary, such as when using other metals, the desired metal nanoparticle dispersion can be obtained by standing or stirring at room temperature or warming. At this time, the reducing agent is preferably adjusted as it is or in an aqueous solution. The temperature for heating varies depending on the type of polymer compound, the metal used, the medium, the type of reducing agent, etc., but is generally 100 ° C. or lower, preferably 80 ° C. or lower.

  Since the metal nanoparticle dispersion of the present invention is stably dispersed for a long period of time in any medium, its use is not limited. For example, catalysts, electronic materials, magnetic materials, optical materials, various sensors It can be used in a very wide range of fields such as color materials and medical examination applications. From the point that the metal species that can be contained and the ratio thereof can be easily adjusted, it is possible to efficiently exhibit the effect according to the purpose. Furthermore, since it is stably dispersed over a long period of time, it can be used for long-term use and long-term storage, and is highly useful. In addition, the method for producing a metal nanoparticle dispersion of the present invention is highly advantageous as an industrial production method because it requires almost no complicated process or precise condition setting.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, “%” represents “mass%”.

  The molecular structure / substance name is abbreviated as follows.

PEI: Polyethyleneimine PEG: Polyethylene glycol PEGM: Polyethylene glycol monomethyl ether EP: Epoxy resin BisAEP: Bisphenol A type epoxy resin PSt: Polystyrene DMA: N, N-dimethylacetamide

In the following examples, the equipment used is as follows.
¹ H-NMR: manufactured by JEOL Ltd., AL300, 300 Hz
Particle size measurement: FPAR-1000, manufactured by Otsuka Electronics Co., Ltd.
TEM photo: JEM-2200FS, manufactured by JEOL Ltd.
TGA measurement: SII Nano Technology Co., Ltd., TG / DTA6300
Plasmon absorption spectrum: manufactured by Hitachi, Ltd., UV-3500
Dialysis: Spectrum, Spectra / Por RC dialysis tube, MWCO3500

Synthesis of Polymer Compound Synthesis Example 1 Synthesis of Polymer Compound (X-1) Having PEG-Branched PEI-BisAEP Structure 1-1 [Synthesis of Tosylated Polyethylene Glycol]
A solution prepared by mixing 150 g of PEGM [number average molecular weight (Mn) 5000] (manufactured by Aldrich) and 24 g (300 mmol) of pyridine with 150 g of chloroform, and 29 g (150 mmol) of tosyl chloride and 30 ml of chloroform were uniformly mixed. Each solution was prepared.

While stirring a mixed solution of PEGM and pyridine at 20 ° C., a toluene solution of tosyl chloride was added dropwise thereto. After completion of the dropping, the reaction was carried out at 40 ° C. for 2 hours. After completion of the reaction, 150 ml of chloroform was added for dilution, washed with 250 ml (340 mmol) of 5% HCl aqueous solution, and then with saturated saline and water. The obtained chloroform solution was dried over sodium sulfate, and then the solvent was distilled off with an evaporator and further dried. The yield was 100%. Each peak was assigned by ¹ H-NMR spectrum (2.4 ppm: methyl group in tosyl group, 3.3 ppm: methyl group at PEGM terminal, 3.6 ppm: EG chain of PEG, 7.3-7.8 ppm) : Benzene ring in tosyl group) and tosylated polyethylene glycol.

1-2 [Synthesis of polymer compound having PEG-branched PEI structure]
After dissolving 23.2 g (4.5 mmol) of the tosylated polyethylene glycol obtained in 1-1 and 15.0 g (1.5 mmol) of branched polyethyleneimine (manufactured by Nippon Shokubai Co., Ltd., Epomin SP200) in 180 ml of DMA, Potassium carbonate 0.12g was added and it was made to react at 100 degreeC under nitrogen atmosphere for 6 hours. After completion of the reaction, the solid residue was removed, and a mixed solvent of 150 ml of ethyl acetate and 450 ml of hexane was added to obtain a precipitate. The precipitate was dissolved in 100 ml of chloroform and reprecipitated again by adding a mixed solvent of 150 ml of ethyl acetate and 450 ml of hexane. This was filtered and dried under reduced pressure. Each peak is assigned by ¹ H-NMR spectrum (2.3 to 2.7 ppm: ethylene of branched PEI, 3.3 ppm: methyl group at PEG end, 3.6 ppm: EG chain of PEG), PEG-branched PEI It was confirmed that the polymer compound had a structure. The yield was 99%.

1-3 [Modification of epoxy resin]
After dissolving 37.4 g (20 mmol) of EPICLON AM-040-P and 2.72 g (16 mmol) of 4-phenylphenol in 100 ml of DMA, 0.52 ml of a 65% ethyl acetate triphenylphosphonium ethanol solution was added, and the temperature was 120 ° C. under a nitrogen atmosphere. For 6 hours. After allowing to cool, the solution was dropped into a large amount of water, and the resulting precipitate was further washed with a large amount of water. The reprecipitation purified product was filtered and dried under reduced pressure to obtain a modified bisphenol A type epoxy resin. The yield of the obtained product was 100%.

^{As a result of 1} H-NMR measurement and considering the integration ratio of epoxy groups, 0.95 epoxy rings remain in one molecule of the bisphenol A type epoxy resin, and the resulting modified epoxy resin has a single bisphenol A skeleton. It was confirmed to be a functional epoxy resin.

1-4 [Synthesis of polymer compound (X-1)]
A bisphenol A type monofunctional epoxy resin obtained in 1-3 above was added to a solution obtained by dissolving 20 g (0.8 mmol) of the polymer compound having a PEG-branched PEI structure obtained in 1-3 above in 150 ml of methanol. A solution in which 4.9 g (2.4 mmol) was dissolved in 50 ml of acetone was dropped in a nitrogen atmosphere, and then the reaction was performed by stirring at 50 ° C. for 2 hours. After completion of the reaction, the solvent was distilled off under reduced pressure, and further dried under reduced pressure to obtain a polymer compound (X-1) having a PEG-branched PEI-BisAEP structure. The yield was 100%.

  30 mg of the polymer compound (X-1) obtained in 1-4 above was added to 10 ml of water and dissolved by stirring. When the particle size distribution state in the solution was measured by the light scattering method, it was confirmed that the dispersion had an average particle size of 110 nm and formed micelles well in water.

Synthesis Example 2 Synthesis of Polymer Compound (X-2) Having PEG-Branched PEI-Naphthalene EP Structure 2-1 [Synthesis of Tosylated Polyethylene Glycol]
A solution in which 100 g of PEGM [Mn2000] (manufactured by Aldrich) 100 g [50 mmol] and 40 g (500 mmol) of pyridine were mixed with 100 ml of chloroform and a solution in which 48 g (250 mmol) of tosyl chloride and 150 ml of chloroform were uniformly mixed were prepared.

While stirring a mixed solution of PEGM and pyridine at 20 ° C., a toluene solution of tosyl chloride was added dropwise thereto. After completion of the dropping, the reaction was carried out at 40 ° C. for 2 hours. After completion of the reaction, the reaction mixture was diluted with 200 ml of chloroform, washed with 420 ml (570 mmol) of 5% HCl aqueous solution, and then with saturated saline and water. The obtained chloroform solution was dried over sodium sulfate, and then the solvent was distilled off with an evaporator and further dried. The yield was 100%. Each peak was assigned by ¹ H-NMR spectrum (2.4 ppm: methyl group in tosyl group, 3.3 ppm: methyl group at PEGM terminal, 3.6 ppm: EG chain of PEG, 7.3-7.8 ppm) : Benzene ring in tosyl group) and tosylated polyethylene glycol.

2-2 [Synthesis of polymer compound having PEG-branched PEI structure]
17.5 g (6.9 mmol) of the tosylated polyethylene glycol obtained in 2-1 above and 57.5 g (2.3 mmol) of branched polyethyleneimine (Aldrich, weight average molecular weight (Mw) 25000) in 300 ml of DMA. After dissolution, 0.24 g of potassium carbonate was added and reacted at 100 ° C. for 6 hours in a nitrogen atmosphere. After completion of the reaction, the solid residue was removed, and a mixed solvent of 250 ml of ethyl acetate and 750 ml of hexane was added to obtain a precipitate. The precipitate was dissolved in 150 ml of chloroform and reprecipitated again by adding a mixed solvent of 250 ml of ethyl acetate and 750 ml of hexane. This was filtered and dried under reduced pressure. Each peak is assigned by ¹ H-NMR spectrum (2.3 to 2.7 ppm: ethylene of branched PEI, 3.3 ppm: methyl group at PEG end, 3.6 ppm: EG chain of PEG), PEG-branched PEI It was confirmed that the polymer compound had a structure. The yield was 99%.

2-3 [Modification of epoxy resin]
Naphthalene-type tetrafunctional epoxy resin EPICLON HP-4700 (manufactured by Dainippon Ink & Chemicals, Inc.) 44.5 g (80 mmol) and 4-phenylphenol 29.9 g (176 mmol) are dissolved in DMA 200 ml, and then 65% ethyltriphenylphosphonium acetate. 1.36 ml of ethanol solution was added and reacted at 120 ° C. for 6 hours under a nitrogen atmosphere. After allowing to cool, the solution was dropped into 150 ml of water, and the resulting precipitate was washed twice with methanol and then dried under reduced pressure at 60 ° C. to obtain a modified naphthalene type epoxy resin. The yield was 100%.

^{As a result of 1} H-NMR measurement and considering the integration ratio of epoxy groups, 0.99 epoxy rings remain in one molecule of naphthalene type tetrafunctional epoxy resin, indicating that it is a monofunctional naphthalene type epoxy resin. confirmed.

2-4 [Synthesis of polymer compound (X-2)]
A monofunctional epoxy having a naphthalene skeleton obtained in the above 2-3 was added to a solution obtained by dissolving 4.65 g (0.5 mmol) of the polymer compound having the PEG-branched PEI structure obtained in the above 2-2 in 40 ml of methanol. A solution prepared by dissolving 1.16 g (1.1 mmol) of the resin in 15 ml of acetone was dropped in a nitrogen atmosphere, and then reacted at 50 ° C. with stirring for 2 hours. After completion of the reaction, the solvent was distilled off under reduced pressure, and further dried under reduced pressure to obtain a polymer compound (X-2) having a PEG-branched PEI-naphthalene EP structure. The yield was 100%.

  30 mg of the polymer compound (X-2) obtained in 2-4 above was added to 10 ml of water and dissolved by stirring. When the particle size distribution state in the solution was measured by the light scattering method, it was confirmed that the dispersion had an average particle size of 110 nm and formed micelles well in water.

Synthesis Example 3 Synthesis of Polymer Compound (X-3) Having PEG-Branched PEI-PSt Structure 1.22 g (0.049 mmol) of the polymer compound having a PEG-branched PEI structure obtained in Synthesis Example 1-2 To a solution dissolved in 44 g of water, 1.9 g of 2 mol / L hydrochloric acid and 1.92 g (18.4 mmol) of styrene monomer were added, and 70% t-butyl hydroperoxide (TBHP) was stirred at 80 ° C. in a nitrogen atmosphere. ) 0.45 g (5.0 mmol) was added and allowed to react for 2 hours. After cooling, purification was performed by dialysis to obtain an aqueous dispersion of a polymer compound (X-3) having a PEG-branched PEI-PSt structure. The yield was 100%.

  Using the aqueous dispersion of the polymer compound (X-3) obtained in Synthesis Example 3 above, the particle size distribution state was measured by a light scattering method. As a result, it was a dispersion having an average particle size of 121 nm and was good in water. It was confirmed that micelles were formed.

Synthesis Example 4 Synthesis of Polymer Compound (X-4) Having PEG-Branched PEI-Polypropylene Glycol Skeleton Urethane Structure 4-1 [Synthesis of Polymer Compound (X-4) Having PEG-Branched PEI Structure]
In Synthesis Example 1-1, a tosylated polyethylene glycol was obtained in the same manner as in Synthesis Example 1-1 except that 60 g [30 mmol] of PEGM [Mn2000] (Aldrich) was used in Synthesis Example 1-1. A polymer compound having a PEG-branched PEI structure was obtained in the same manner as in Synthesis Example 1-2 except that 9.7 g (4.5 mmol) of tosylated polyethylene glycol was used.

4-2 [Synthesis of polypropylene glycol (PG) skeleton urethane]
After distilling 13.0 g (101 mmol) of dibutylamine to 20.1 g (50 mmol) of dipropylene glycol diglycidyl ether EPICLON 705 (Dainippon Ink Chemical Co., Ltd.) in a nitrogen atmosphere at 70 ° C. for 0.5 hours. The mixture was reacted at 90 ° C. for 7 hours to obtain a dibutylamino PG reaction solution at both ends. Next, in the mixed solution of 19.4 g (100 mmol) of diisocyanate, 0.04 g (0.1 mmol) of tin octylate and 80 g of chloroform, the synthesized dibutylamino PG reaction solution at both ends was synthesized at 40 ° C., 0.5 After dropwise addition over time, an addition reaction was carried out at 50 ° C. for 5 hours. Further, 5.7 g (50 mmol) of cyclohexanemethanol was added dropwise at 40 ° C. for 20 minutes, followed by addition reaction at 50 ° C. for 5 hours to obtain a polypropylene glycol skeleton urethane solution.

4-3 [Synthesis of polymer compound (X-4)]
2.76 g of the polypropylene glycol skeleton urethane obtained in 4-2 above was added to a solution obtained by dissolving 16.0 g (1 mmol) of the polymer compound having the PEG-branched PEI structure obtained in 4-1 in 30 ml of chloroform. A solution obtained by dissolving (2 mmol) in 10 ml of chloroform was dropped in 10 minutes in a nitrogen atmosphere, and then reacted at 40 ° C. with stirring for 2 hours. After completion of the reaction, 340 g of a mixed solvent of water and acetone 1: 1 (volume ratio) was added, chloroform and acetone were distilled off under reduced pressure, and a polymer compound having a PEG-branched PEI-polypropylene glycol skeleton urethane structure (X -4) was obtained. The yield was 100%.

  When the particle size distribution state was measured by a light scattering method using 10 ml of the aqueous dispersion of the polymer compound (X-4) obtained above, it was a dispersion having an average particle size of 107 nm and was well micelle in water. Was confirmed to form.

Synthesis Example 5 Synthesis of Polymer Compound (X-5) Having PEG-Branched PEI-Polycarbonate Skeleton Urethane Structure 5-1 [Synthesis of Polycarbonate Skeleton Urethane]
To a mixed solution of 19.4 g (100 mmol) of diisocyanate, 0.04 g (0.1 mmol) of tin octylate, and 100 g of chloroform, 49.0 g (50 mmol) of polycarbonate diol was added at 40 ° C. for 0.5 hour in a nitrogen atmosphere. Then, addition reaction was carried out at 50 ° C. for 5 hours to obtain a reaction solution of both end isocyanate urethanes. Next, 5.7 g (50 mmol) of cyclohexanemethanol was dropped into the synthesized both-end isocyanate urethane reaction solution at 40 ° C. for 20 minutes, followed by addition reaction at 50 ° C. for 5 hours to obtain a one-end isocyanate polycarbonate skeleton urethane reaction solution. It was.

5-2 [Synthesis of polymer compound (X-5)]
One-end isocyanate polycarbonate skeleton urethane reaction obtained from Synthesis 5-1 above in a solution obtained by dissolving 16.0 g (1 mmol) of the polymer compound having a PEG-branched PEI structure obtained in Synthesis Example 4-1 in 30 ml of chloroform A solution in which 7.0 g (2 mmol) of the solution was dissolved in 10 ml of chloroform was dropped in 10 minutes in a nitrogen atmosphere, and then reacted at 40 ° C. with stirring for 2 hours. After completion of the reaction, 340 g of a mixed solvent of water and acetone 1: 1 (volume ratio) was added, chloroform and acetone were distilled off under reduced pressure, and a polymer compound having a PEG-branched PEI-polycarbonate skeleton urethane structure (X- An aqueous dispersion 5) was obtained. The yield was 100%.

  When the particle size distribution state was measured by a light scattering method using 10 ml of the aqueous dispersion of the polymer compound (X-5) obtained in the above 5-2, it was a dispersion having an average particle size of 112 nm. It was confirmed that micelles were formed satisfactorily.

Example 1
A solution 1A obtained by dissolving 20 mg (EI unit: 0.15 mmol) of the polymer compound (X-1) obtained in Synthesis Example 1 in 2.39 g of water, and 0.16 g (0.97 mmol) of silver nitrate in 1.30 g of water A dissolved solution 1B and a solution 1C in which 0.12 g (0.48 mmol) of sodium citrate was dissolved in 0.25 g of water were prepared. While stirring at 25 ° C., solution 1B was added to solution 1A, followed by solution 1C. The dispersion gradually changed to dark brown. After stirring for 7 days, it was purified by dialysis to obtain an aqueous dispersion.

  One part of the obtained aqueous dispersion was sampled, and a peak of a plasmon absorption spectrum was observed at 400 nm by a visible absorption spectrum measurement of a 10-fold diluted solution, confirming the formation of silver nanoparticles. Moreover, it confirmed that it was 20 nm or less silver nanoparticle from the TEM photograph of FIG. After removing the solvent of the aqueous dispersion of the obtained silver nanoparticle dispersion, the silver content was measured by TGA measurement. As a result, it was 83%. In addition, it was confirmed that the aqueous dispersion of the obtained silver nanoparticle dispersion was excellent in storage stability without aggregation or precipitation even after 2 months.

Example 2
In Example 1, an aqueous dispersion was obtained in the same manner as in Example 1 except that the solution 1C was added to the solution 1A and subsequently the solution 1B was added. The obtained aqueous dispersion was stable, 1 part of the dispersion was sampled, and a peak of a plasmon absorption spectrum was observed at 400 nm by a visible absorption spectrum measurement of a 10-fold diluted solution, confirming the formation of silver nanoparticles.

Example 3
An aqueous dispersion was obtained in the same manner as in Example 10, except that the solution 1C was added to the solution 1A in Example 1 and stirred for 7 days, then the solution 1B was added and further stirred for 7 days. The obtained aqueous dispersion was stable, 1 part of the dispersion was sampled, and a peak of a plasmon absorption spectrum was observed at 400 nm by a visible absorption spectrum measurement of a 10-fold diluted solution, confirming the formation of silver nanoparticles.

Example 4
Example 1 was the same as Example 1 except that solution 1B was prepared by dissolving 0.008 g (0.048 mmol) of silver nitrate in 1.30 g of water and preparing a solution in which solution 1C was added by 0.25 g of water. Thus, an aqueous dispersion was obtained. The obtained aqueous dispersion was stable, 1 part of the dispersion was sampled, and a peak of a plasmon absorption spectrum was observed at 400 nm by a visible absorption spectrum measurement of a 10-fold diluted solution, confirming the formation of silver nanoparticles.

Example 5
A solution 2A obtained by dissolving 20 mg (EI unit: 0.15 mmol) of the polymer compound (X-2) obtained in Synthesis Example 2 in 2.39 g of water, and 0.16 g (0.97 mmol) of silver nitrate were dissolved in 1.30 g of water. Solution 2B and solution 2C prepared by dissolving 0.12 g (0.48 mmol) of sodium citrate in 0.25 g of water were prepared. While stirring at 25 ° C., solution 2B was added to solution 2A, followed by solution 2C. The dispersion gradually changed to dark brown. After stirring for 7 days, an aqueous dispersion was obtained. The obtained aqueous dispersion was stable, 1 part of the dispersion was sampled, and a peak of a plasmon absorption spectrum was observed at 400 nm by a visible absorption spectrum measurement of a 10-fold diluted solution, confirming the formation of silver nanoparticles.

Example 6
A silver nitrate aqueous solution in which 0.02 g (0.12 mmol) of silver nitrate is dissolved in 5.0 g of water in 5.0 g (EI unit: 0.41 mmol) of the polymer compound (X-3) obtained in Synthesis Example 3. And stirred at 25 ° C. The dispersion gradually turned light brown. Seven days later, the mixture was purified by dialysis to obtain an aqueous dispersion. The obtained aqueous dispersion was stable, 1 part of the dispersion was sampled, and a peak of a plasmon absorption spectrum was observed at 400 nm by a visible absorption spectrum measurement of a 10-fold diluted solution, confirming the formation of silver nanoparticles.

Example 7
Instead of the solution 1A of Example 1, a solution obtained by adding 2.29 g of water to 0.12 g (EI unit: 0.15 mmol) of the aqueous dispersion of the polymer compound (X-4) obtained in Synthesis Example 4 was used. An aqueous dispersion was obtained in the same manner as in Example 1 except that it was used. The obtained aqueous dispersion was stable, 1 part of the dispersion was sampled, and a peak of a plasmon absorption spectrum was observed at 400 nm by a visible absorption spectrum measurement of a 10-fold diluted solution, confirming the formation of silver nanoparticles.

Example 8
Instead of the solution 1A of Example 1, a solution obtained by adding 2.28 g of water to 0.12 g (EI unit: 0.15 mmol) of the aqueous dispersion of the polymer compound (X-5) obtained in Synthesis Example 5 was used. An aqueous dispersion was obtained in the same manner as in Example 1 except that it was used. The obtained aqueous dispersion was stable, 1 part of the dispersion was sampled, and a peak of a plasmon absorption spectrum was observed at 400 nm by a visible absorption spectrum measurement of a 10-fold diluted solution, confirming the formation of silver nanoparticles.

Example 9
In Example 1, Solution 1B was prepared by dissolving 0.018 g (0.048 mmol) of sodium tetrachloroplatinum (II) hydrate in 1.30 g of water, and preparing 1C of Solution 1C as 0.25 g of water. Except that, an aqueous dispersion of the polymer dispersion was obtained in the same manner as in Example 1. The color of the solution gradually changed from orange of tetrachloroplatinum (II) sodium to brown. The aqueous dispersion obtained was stable.

Comparative Example 1
In a solution of 5 g (0.5 mmol) of branched PEI (manufactured by Nippon Shokubai Co., Ltd., Epomin SP200) dissolved in 150 ml of methanol, 3.0 g of bisphenol A type monofunctional epoxy resin obtained from Synthesis Example 1 (1. 5 mmol) in 60 ml of acetone was added dropwise under a nitrogen atmosphere, and the reaction was carried out by stirring at 50 ° C. for 2 hours. After completion of the reaction, the polymer compound having a BisAEP-branched PEI structure (yield 100%) was obtained by drying under reduced pressure.

  30 mg of the polymer compound obtained above was added to 10 ml of water and dissolved by stirring. When the particle size distribution state in the solution was measured by a light scattering method, a measurement result having an average particle size of 110 nm was obtained, and it was confirmed that micelles were formed well in water.

  A solution 3A in which 6.6 mg (EI unit: 0.097 mmol) of the polymer compound having the BisAEP-branched PEI structure obtained above was dissolved in 2.39 g of water, and 0.16 g (0.97 mmol) of silver nitrate were added to 1.30 g of water. Solution 3B dissolved in 1 and sodium citrate 0.12 g (0.48 mmol) dissolved in water 0.25 g were prepared. While stirring at 25 ° C., solution 3B was added to solution 3A, followed by solution 3C. The dispersion gradually changed to a dark brown color, followed by precipitation, and the dispersion components completely disappeared after 2 days.

Application example 1
The dispersion of the silver nanoparticle dispersion obtained in Example 2 was concentrated by centrifugation, and 5 g of isopropyl alcohol (IPA) was added to 2 g of the thick layer and mixed. (The content of the silver nanoparticle dispersion in the IPA dispersion was 14%.) There was no change in the dispersion state, and a stable IPA dispersion was obtained. The IPA dispersion was cast on a glass substrate and then heat-treated at 200 ° C. for 30 minutes under nitrogen. It was 8.7 * 10 <^-4> ohm * cm when the volume specific resistivity (Mitsubishi Chemical Corporation make, Loresta-GP MCP-T610) was measured.

2 is a TEM photograph of a silver nanoparticle dispersion obtained in Example 1. FIG.

Claims (10)

A dispersion of a polymer compound (X) having a branched polyalkyleneimine chain (a), a hydrophilic segment (b), and a hydrophobic segment (c), and metal nanoparticles (Y) Metal nanoparticle dispersion characterized by. The metal nanoparticle dispersion according to claim 1, wherein the branched polyalkyleneimine chain (a) is a branched polyethyleneimine chain. The metal nanoparticle dispersion according to claim 1, wherein a molar ratio of (tertiary amine) / (all amines) in the branched polyalkyleneimine chain (a) is 1 to 49/100. The metal nanoparticle dispersion according to claim 1, wherein a molar ratio of (tertiary amine) / (all amines) in the branched polyalkyleneimine chain (a) is 15 to 40/100. The metal nanoparticle dispersion according to claim 1, wherein the hydrophilic segment (b) is a polyoxyalkylene chain. The hydrophobic segment (c) is a residue of one or more compounds selected from the group consisting of polystyrene, poly (meth) acrylic acid ester, epoxy resin, polyurethane, polycarbonate and polyacylalkyleneimine having a hydrophobic substituent. The metal nanoparticle dispersion according to claim 1. The metal nanoparticle dispersion according to claim 1, wherein the metal nanoparticles (Y) are one or more metals selected from the group consisting of silver, gold, and platinum. The metal nanoparticle dispersion according to any one of claims 1 to 7, wherein the metal nanoparticles (Y) have a particle diameter of 1 to 50 nm. After a polymer compound having a branched polyalkyleneimine chain, a hydrophilic segment, and a hydrophobic segment is dispersed in a solvent, a metal salt or a metal ion solution is added to reduce the metal ion to form a metal nanoparticle. The manufacturing method of the metal nanoparticle dispersion characterized by setting it as particle | grains. The method for producing a metal nanoparticle dispersion according to claim 9, wherein a reducing agent is used when reducing metal ions.

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