JP2008274123A - Core-shell fine particle, its manufacturing method and manufacturing method of fixed colloid crystal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a core-shell fine particle that can easily initiate polymerization and gives a cured product exhibiting sufficient mechanical strength, its manufacturing method and a manufacturing method of a fixed colloid crystal. <P>SOLUTION: The core-shell fine particle is constituted of a core fine particle and, covering the outer periphery thereof, a shell layer comprised of a graft chain bearing a photopolymerization-initiating group. The core-shell fine particle has an average particle size of 100-950 nm with a CV value of at most 20% as a percentage of the standard deviation of the average particle size to the average particle size as measured by the dynamic light scattering method. Preferably, the photopolymerization-initiating group is a functional group represented by chemical formula (1). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to core-shell fine particles capable of forming an immobilized colloidal crystal having mechanical strength, a method for producing the same, and production of an immobilized colloidal crystal capable of regularly arranging the core-shell fine particles in a matrix. Regarding the method.

  When light enters a colloidal crystal in which monodisperse fine particles are regularly arranged three-dimensionally, diffraction interference occurs, and light of a specific wavelength is reflected mainly depending on the periodic structure. When the reflected wavelength occurs in the visible region, it can be visually recognized as structural color development. Numerous studies have been conducted on colloidal crystals, and development of various optical elements such as photonic crystals and optical functional materials is expected. For example, it can be applied to optical filters, optical switches, sensors, lasers, and the like.

  Many examples of research have already been reported on the method of producing colloidal crystals. Among them, it is disclosed that core-shell particles having a high density of graft chains formed on the surface of fine particles form colloidal crystals due to steric repulsion between graft chains in a dispersed state in an organic solvent ( For example, see Patent Document 1). The core-shell fine particles shown here mean fine particles in which the graft chains are immobilized on the surface of the core fine particles at a sufficient density with one end of the graft chains forming the shell layer as a bonding point.

  However, since the colloidal crystal formed in the organic solvent has a liquid matrix, the regular arrangement easily collapses due to a slight external force such as vibration and disturbance from the environment such as a temperature change. For this reason, it is necessary to fix colloidal crystals for practical use. Hereinafter, this immobilized colloidal crystal is referred to as an immobilized colloidal crystal.

There has been disclosed a method of immobilizing an organic solvent by containing a small amount of monomer and polymerizing the monomer (for example, see Patent Document 2). However, the immobilized colloidal crystal obtained by this method is immobilized as a gel whose matrix contains about 50% of an organic solvent (acetonitrile). In the gel-like immobilized colloidal crystal, when the organic solvent is volatilized, there is a possibility that the crystal structure is broken or the crystal structure is distorted. Further, since it is an organogel containing an organic solvent, its mechanical strength is low, and practical application to the optical functional material has been difficult in practice.
International Publication No. WO2005 / 108451 (Pages 2 and 3) International Publication WO2003 / 100139 (pages 4 and 9)

  However, in the technique described in Patent Document 2, for example, when obtaining immobilized colloidal crystals, silica composite fine particles are mixed with acetonitrile as the organic solvent, ethylene dimethacrylate, methyl methacrylate as the polymerizable substance, and 2, 2 as the polymerization initiator. It is necessary to polymerize by adding '-azobisisobutyronitrile (AIBN). For this reason, the polymer obtained by the polymerization of the polymerizable substance has a weak binding property with the silica composite fine particles and also has a low dispersibility of the silica composite fine particles, so that the mechanical strength of the cured product cannot be fully exhibited. There was a problem.

  Therefore, an object of the present invention is to provide core-shell fine particles that can easily start polymerization and that the obtained cured product can exhibit sufficient mechanical strength, a method for producing the same, and immobilized colloidal crystals. It is in providing the manufacturing method of.

  In order to achieve the above object, the core-shell microparticles of the first invention in the present invention are configured by coating the outer periphery of the core microparticles with a shell layer made of a graft chain having a photopolymerization initiating group. The average particle diameter measured by the light scattering method is 100 to 950 nm, and the CV value representing the percentage of the particle diameter standard deviation with respect to the average particle diameter is 20% or less.

  The core-shell fine particles of the second invention are characterized in that, in the first invention, the photopolymerization initiating group is a functional group represented by the following chemical formula (1).

第３の発明のコア−シェル微粒子の製造方法は、第１又は第２の発明のコア−シェル微粒子の製造方法であって、リビングラジカル重合開始基を有するコア微粒子に、重合性二重結合及び光重合開始基を有する単量体（Ａ）と、該単量体（Ａ）以外の単量体とをグラフト重合してシェル層を形成することを特徴とする。

The method for producing core-shell fine particles of the third invention is the method for producing core-shell fine particles of the first or second invention, wherein the core fine particles having a living radical polymerization initiating group are bonded with a polymerizable double bond and A shell layer is formed by graft polymerization of a monomer (A) having a photopolymerization initiating group and a monomer other than the monomer (A).

  In the method for producing core-shell fine particles of the fourth invention, in the third invention, the polymerizable double bond of the monomer (A) is an acryloyl group, a methacryloyl group or a styryl group, and a photopolymerization initiating group. Is a functional group represented by the following chemical formula (1).

第５の発明の固定化コロイド結晶の製造方法は、第１又は第２の発明のコア−シェル微粒子を単量体中に分散させてコロイド結晶を得た後、光照射して硬化させることを特徴とする。

The method for producing an immobilized colloidal crystal according to a fifth aspect of the invention is to obtain a colloidal crystal by dispersing the core-shell fine particles of the first or second aspect of the invention in a monomer, and then to cure by irradiation with light. Features.

According to the present invention, the following effects can be exhibited.
The core-shell fine particles of the first invention are constituted by covering the outer periphery of the core fine particles with a shell layer made of a graft chain having a photopolymerization initiating group. For this reason, when a monomer is added to the core-shell fine particles for polymerization, it is not necessary to add a new polymerization initiator, and the polymerization can be carried out quickly by light irradiation. Combined and integrated, it can develop strength. Therefore, the core-shell fine particles can easily start polymerization, and the obtained cured product can exhibit sufficient mechanical strength. The core-shell fine particles have an average particle size of 100 to 950 nm and are on the order of submicron (0.1 μm), and are monodispersed with a CV value representing a percentage of the standard deviation of the particle size with respect to the average particle size of 20% or less. Is.

  In the core-shell fine particles of the second invention, since the photopolymerization initiating group is a functional group represented by the chemical formula (1), in addition to the effects of the first invention, the photopolymerization initiating group is efficiently added to the graft chain. And sufficient radicals can be generated easily by light irradiation.

  In the method for producing core-shell fine particles of the third invention, the monomer (A) having a polymerizable double bond and a photopolymerization initiating group is added to the core fine particles having a living radical polymerization initiating group, and the monomer ( A shell layer is formed by graft polymerization with monomers other than A). For this reason, graft polymerization can be easily advanced by the living radical polymerization initiating group, and the photopolymerization initiating group can be introduced into the core-shell fine particles. Therefore, the core-shell fine particles can be easily cured by light irradiation using the photopolymerization initiating group, and the cured product can exhibit sufficient mechanical strength.

  In the method for producing core-shell fine particles of the fourth invention, in addition to the effects of the third invention, the polymerizable double bond of the monomer (A) is polymerized by being an acryloyl group, a methacryloyl group or a styryl group. Can increase the sex. In addition, since the photopolymerization initiating group is a functional group represented by the chemical formula (1), the photopolymerization initiating group can be efficiently introduced into the graft chain, and an easy and sufficient radical is generated by light irradiation. Can be made.

  In the method for producing an immobilized colloidal crystal according to a fifth aspect of the invention, the core-shell fine particles are dispersed in a monomer to obtain a colloidal crystal, and then cured by irradiation with light. For this reason, the crystal particles can be immobilized and the mechanical strength of the immobilized colloidal crystal can be improved.

Hereinafter, embodiments that are considered to be the best modes of the present invention will be described in detail.
The core-shell fine particles (hair particles) in the present embodiment are formed by coating the outer periphery of the core fine particles as a core layer with a shell layer made of a graft chain having a photopolymerization initiating group, and measured by a dynamic light scattering method. The average particle size is 100 to 950 nm, and the CV value representing the percentage of the particle size standard deviation with respect to the average particle size is 20% or less. When the average particle diameter is in the above range, the core-shell fine particles can maintain a submicron (0.1 μm order) size. Moreover, when the CV value of the core-shell fine particles is 20% or less, the particle size distribution of the core-shell fine particles can be narrowed and sharpened, and the characteristics of the core-shell fine particles can be improved.

  The method for producing core-shell fine particles includes a first step of producing core fine particles having a living radical polymerization initiating group, and a polymerizable radical bond and a photopolymerization initiating group using the living radical polymerization initiating group of the core fine particles. And a step of graft-polymerizing a monomer (A) other than the monomer (A) (monomer mixture) to form a shell layer.

  In the first step, as a living radical polymerization initiating group contained in the core fine particles, a polymerization initiating group of polymerization (NMP: Nitroxide-Mediated Polymerization) using a nitroxide compound (alkoxyamine compound), an atom transfer radical polymerization (ATRP: Atom) A polymerization initiation group of transfer radical polymerization (RAFT), a polymerization initiation group of reversible addition-fragmentation chain transfer (RAFT) polymerization, or the like can be used. Among them, polymerization initiator groups using nitroxide compounds (core fine particles containing alkoxyamine groups) and atom transfer radical polymerization initiator groups (core fine particles containing ATRP initiator groups) are used from the standpoint of graft efficiency. It is preferable to do.

  As a polymerization initiating group for polymerization using a nitroxide compound, a functional group represented by the following chemical formula (2) is preferable.

但し、式中、Ｒ^１〜Ｒ^６はそれぞれ独立に選択されるものであり、水素、炭化水素基（−Ｒ^７）、エステル基（−ＣＯＯＲ^８）、アルコキシ基（−ＯＲ^９）又はホスホネート基（−ＰＯ（ＯＲ^１０）_２）を表す。ここで、Ｒ^７〜Ｒ^１０はそれぞれ独立した炭素数１〜８の直鎖、分岐又は環状の飽和又は不飽和の炭化水素基を表す。また、Ｒ^３とＲ^４が互いに連結した炭素数３〜１２の環式構造を形成していてもよい。但し、環式構造の場合には、未置換又は、炭素数１〜４のアルキル基、ヒドロキシル基、アセトキシ基、ベンゾイルオキシ基、メトキシ基又はオキソ基で置換されたものである。

However, in the formula, R ^{1 to} R ⁶ are each independently selected from hydrogen, hydrocarbon group (—R ⁷ ), ester group (—COOR ⁸ ), alkoxy group (—OR ⁹ ), or phosphonate group. It represents a _{^{(-PO (OR 10) 2)}} . Here, R < ⁷ > -R < ¹⁰ > represents a C1-C8 linear, branched or cyclic saturated or unsaturated hydrocarbon group which was respectively independent. Further, R ³ and R ⁴ may form a cyclic structure having 3 to 12 carbon atoms linked to each other. However, in the case of a cyclic structure, it is unsubstituted or substituted with an alkyl group having 1 to 4 carbon atoms, a hydroxyl group, an acetoxy group, a benzoyloxy group, a methoxy group or an oxo group.

  The polymerization initiation group for atom transfer radical polymerization is preferably a functional group represented by the following chemical formula (3) or chemical formula (4).

但し、式中Ｒ^１１及びＲ^１２は、それぞれ独立して、水素原子、炭素数１〜８のアルキル基、炭素数６〜８のアリール基、炭素数６〜８のアルキルアリール基であり、Ｘはハロゲン原子を表す。

In the formula, R ¹¹ and R ¹² are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 8 carbon atoms, or an alkylaryl group having 6 to 8 carbon atoms, Represents a halogen atom.

  The material of the core fine particle is not particularly limited as long as it is stably dispersed in the dispersion medium. For example, polystyrene, styrene-butadiene copolymer, styrene-divinylbenzene copolymer, organic polymer fine particles such as poly (meth) acrylate, metal oxide fine particles such as silica, titania and zirconia, metal fine particles such as gold and silver Can be used.

  A known method is employed when producing the core fine particles. For example, when synthesizing fine polymer particles, a method of synthesizing by copolymerizing a monomer containing a living radical polymerization initiating group, a compound having a living radical polymerization initiating group and a reactive functional group, Examples of the method include introducing by reacting with the functional group on the surface of the synthesized fine particles, and the method is not particularly limited. For example, after absorbing a monomer mixture containing a crosslinkable monomer having a plurality of vinyl groups and a monomer containing a living radical polymerization initiating group into organic seed particles, the monomer mixture is polymerized. A method is mentioned.

  The monomer containing a living radical polymerization initiating group is not particularly limited as long as it contains a living radical polymerization initiating group and a polymerizable double bond in the same molecule. For example, as a monomer for introducing a polymerization initiating group for polymerization using a nitroxide compound, 2- (4′-hydroxy-2 ′, 2 ′, 6 ′, 6′-tetramethyl-1′-pi Peridinyloxy) -2- (4′-vinylphenyl) ethanol, 2- (4′-hydroxy-2 ′, 2 ′, 6 ′, 6′-tetramethyl-1′-piperidinyloxy) -2- (3′-vinylphenyl) ethanol, 2- (2 ′, 2 ′, 6 ′, 6′-tetramethyl-1′-piperidinyloxy) -2- (4′-vinylphenyl) ethanol, 2-isopropyl Oxycarbonyloxy-1- (4′-acetoxy-2 ′, 2 ′, 6 ′, 6′-tetramethyl-1′-piperidinyloxy) -1- (4′-vinylphenyl) ethane, 2- ( Nt-butyl-N- (2′-methyl-1- Enylpropyl) aminooxy) -2- (4′-vinylphenyl) ethanol, 2-isopropyloxycarbonyloxy-1- (Nt-butyl-N- (1′-diethylphosphono-2 ′, 2′-) And (dimethylpropyl) aminooxy) -1- (4′-vinylphenyl) ethane.

  Examples of monomers for introducing a polymerization initiation group for atom transfer radical polymerization include 2-bromoisobutyric acid 4-vinylphenyl ester, 1- (1-bromoethyl) -4-vinylbenzene, 4-vinylbenzenesulfonic acid chloride, and the like. Is mentioned. These monomers containing a living radical polymerization initiating group may be used alone or in appropriate combination of two or more.

  The crosslinkable monomer having a plurality of vinyl groups is preferably a polyfunctional monomer having 2 to 6 vinyl groups. For example, divinylbenzene, divinylnaphthalene, ethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra Polyfunctional monomers such as (meth) acrylate and dipentaerythritol hexa (meth) acrylate are exemplified. These crosslinkable monomers may be used alone or in combination of two or more.

  Examples of the polymer constituting the organic seed particles include styrene-based polymers, styrene-butadiene copolymers, styrene copolymers such as styrene- (meth) acrylic acid ester copolymers, and methyl methacrylate polymers. Examples include (meth) acrylic acid ester polymers and copolymers. The polymer is preferably a polymer that sufficiently absorbs the monomer, and can be appropriately selected. As a method for synthesizing the organic seed particles, known polymerization methods such as a soap-free emulsion polymerization method, a dispersion polymerization method, a suspension polymerization method, and an emulsion polymerization method can be applied, and are not particularly limited. Among these, it is preferable to use a soap-free emulsion polymerization method from the viewpoint that the particle surface is clean and that the monodispersity with a narrow particle size distribution can be exhibited.

  The monomer mixture is polymerized with a known radical polymerization initiator to obtain core fine particles having a living radical polymerization initiating group. Examples of the radical polymerization initiator include organic peroxides such as benzoyl peroxide, lauroyl peroxide, t-butylperoxy 2-ethylhexanoate, and diisopropyl peroxydicarbonate; 2,2′-azobisisobutyronitrile, Azo compounds such as 2′-azobis (2,4-dimethylvaleronitrile), 4,4′-azobis-4-cyanovaleric acid, 2,2′-azobis-2-aminodinopropane hydrochloride, potassium persulfate, A persulfate such as ammonium persulfate is used.

  The average particle size of the core fine particles is appropriately selected according to the average particle size of the core-shell fine particles to be obtained, but the average particle size measured by the dynamic light scattering method is usually 50 to 900 nm, preferably Is 80-800 nm. The particle size distribution of the core fine particles is represented by a CV value [(particle diameter standard deviation / average particle diameter) × 100], and the CV value is preferably 20% or less, and more preferably 15% or less.

  Next, in the second step, a monomer (A) having a polymerizable double bond and a photopolymerization initiating group based on the living radical polymerization initiating group of the core fine particles, and a monomer other than the monomer (A) are used. A shell layer is formed by graft polymerization with a monomer to produce core-shell fine particles. By this graft polymerization, a photopolymerization initiating group can be introduced into the graft chain forming the shell layer.

  The monomer (A) is not particularly limited as long as it is a monomer having a polymerizable double bond and a photopolymerization initiating group that generates a radical by light in the molecule. As the monomer (A), the polymerizable double bond is preferably an acryloyl group, a methacryloyl group or a styryl group, and the photopolymerization initiating group is represented by the general formula (1) having excellent photopolymerization initiating ability. Is.

  Specifically, the photopolymerization initiating group is 2-hydroxy-2-methyl-1- {4- [2- (4-vinylbenzyloxy) ethoxy] phenyl} propane-1 represented by the following chemical formula (5). -On,

下記の化学式（６）で表される２−［４−（２−ヒドロキシ−２−メチル−プロピオニル）フェノキシ］エチルアクリレート、

2- [4- (2-hydroxy-2-methyl-propionyl) phenoxy] ethyl acrylate represented by the following chemical formula (6),

下記の化学式（７）で表される２−｛２−［４−（２−ヒドロキシ−２−メチル−プロピオニル）フェノキシ］エトキシカルボニルオキシ｝エチルメタクリレート

2- {2- [4- (2-hydroxy-2-methyl-propionyl) phenoxy] ethoxycarbonyloxy} ethyl methacrylate represented by the following chemical formula (7)

等が挙げられる。これらの光重合開始基は、光照射により容易かつ十分なラジカルを発生させることができ、特に好ましいものである。

Etc. These photopolymerization initiating groups are particularly preferable because they can easily and sufficiently generate radicals by light irradiation.

  As the monomer other than the monomer (A), a monofunctional monomer is preferable in order to perform graft polymerization smoothly. Examples of such monofunctional monomers include styrene monomers such as styrene, p-methylstyrene, α-methylstyrene, 2-vinylnaphthalene, p-methoxystyrene, ethylvinylbenzene; (meth) acrylic Examples of acid ester monomers include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (Meth) acrylic acid ester monomers such as glycidyl (meth) acrylate, methoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, methoxypropylene glycol (meth) acrylate; Unsaturated carboxylic acid monomers such as tonic acid; unsaturated dicarboxylic acid monomers such as maleic acid, fumaric acid and itaconic acid; acid anhydride monomers such as maleic anhydride and itaconic anhydride; dimethyl fumarate; Fumarate monomers such as dicyclohexyl fumarate; isocyanate group-containing monomers such as 2-isocyanatoethyl (meth) acrylate and m-isopropenyl-α, α-dimethylbenzyl isocyanate; N, N-dimethylamino Nitrogen-containing alkyl (meth) acrylates such as ethyl (meth) acrylate and Nt-butylaminoethyl (meth) acrylate; amide group-containing single amounts such as acrylamide, N, N-dimethyl (meth) acrylamide and N-isopropylacrylamide Body, aromatic nitrogen-containing monomers such as 2-vinylpyridine and 4-vinylpyridine; pigs Vinyl ester monomers such as vinyl acetate; ene, isoprene, conjugated diene monomer of chloroprene, vinyl pyrrolidone, vinyl carbazole, acrylonitrile. Furthermore, if necessary, a water-soluble monomer, an ionic monomer, a monomer having another functional group, or the like can be used. Moreover, according to the objective, it can use individually or in combination of 2 or more types.

  The content of the monomer (A) in the total amount of monomers other than the monomer (A) and the monomer (A) is preferably 0.1 to 50% by mass, and 1 to 30% by mass. Further preferred. When the content of the monomer (A) is less than 0.1% by mass, polymerization initiation due to light irradiation is not sufficient, so that a good cured product cannot be obtained. On the other hand, when the amount is more than 50% by mass, the light transmittance due to light irradiation is not sufficient, and therefore when the light is irradiated, a difference in polymerization rate occurs between the surface and the bottom, and the ordered arrangement of the core fine particles may be destroyed.

  The total amount of the monomer (A) and the monomer other than the monomer (A) is appropriately selected depending on the molecular weight of the desired graft chain, but is usually preferably 10 to 100 parts by mass of the core fine particles. The amount is 10,000 parts by mass, more preferably 50 to 2000 parts by mass.

  In order to carry out the polymerization so that the graft chains extend uniformly from the surface of the core fine particles, and to suppress the aggregation of the core fine particles, a free polymerization initiator that is not bonded to the core fine particles can be used in combination as necessary. For example, when polymerization using a nitroxide compound is used as such a polymerization initiator, 2- (4′-hydroxy-2 ′, 2 ′, 6 ′, 6′-tetramethyl-1′-piperidi Nyloxy) -2-phenylethanol, 2- (Nt-butyl-N- (2′-methyl-1-phenylpropyl) aminooxy) -2-phenylethanol, 2-isopropyloxycarbonyloxy-1- ( Nt-butyl-N- (1′-diethylphosphono-2 ′, 2′-dimethylpropyl) aminooxy) -1-phenylethane and the like. Moreover, when utilizing atom transfer radical polymerization, 1-bromo- phenylethane, phenyl 2-bromoisobutyrate, p-toluenesulfonic acid chloride, etc. are mentioned.

Furthermore, when utilizing atom transfer radical polymerization, it is normally performed by adding a transition metal complex as a catalyst. The transition metal complex can be represented by the following general formula (8).
MZ (D) (8)
In the formula, M represents a transition metal, Z represents a halogen atom, and (D) represents a ligand.

  Although M will not be restrict | limited especially if it is a transition metal, A copper atom is preferable. As the halogen atom for Z, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom or the like is selected, and a bromine atom is preferable. The ligand is not particularly limited as long as it can coordinate with a transition metal, but a polydentate ligand such as 2,2′-bipyridyl, 2,2′-bi-4-heptylpyridyl, 2- (N -Pentyliminomethyl) pyridine, spartel, tris (2-dimethylaminoethyl) amine, 1,1,4,7,7-pentamethyldiethylenetriamine, 1,1,4,7,10,10-hexamethyltriethylenetetra An amine or the like is used. These ligands can be used alone or in combination of two or more.

  As the polymerization form, known methods such as bulk polymerization method, suspension polymerization method, solution polymerization method and emulsion polymerization method are adopted, and the types of core fine particles and monomers, polymerization temperature, desired graft chain molecular weight, etc. Is appropriately selected. For example, when the solution polymerization method is adopted, a solvent that forms a shell layer and a solvent that dissolves the polymer are selected as the solvent. Examples of such solvents include aromatic hydrocarbon solvents such as toluene and xylene, ketone solvents such as methyl ethyl ketone and isobutyl ketone, ester solvents such as butyl acetate, alcohol solvents such as methanol and butyl alcohol, and ethylene glycol. Ethylene glycol monomethyl ether, ethylene glycol solvents such as ethylene glycol monomethyl ether acetate, diethylene glycol solvents such as diethylene glycol and diethylene glycol dimethyl ether, propylene glycol solvents such as propylene glycol and propylene glycol methyl ether acetate, N, N-dimethylformamide, Examples thereof include nitrogen and sulfur-containing organic compounds such as acetonitrile and dimethyl sulfoxide. These solvents are used alone or as a mixture.

  The polymerization temperature in the graft polymerization for producing the core-shell fine particles is preferably 20 to 150 ° C, more preferably 40 to 130 ° C. When the polymerization temperature is lower than 20 ° C., the polymerization rate becomes slow, and as a result, the polymerization time becomes longer, which is not preferable. On the other hand, when the temperature is higher than 150 ° C., it is difficult to control the polymerization rate and the polymerization from the surface of the core fine particles is not uniform, resulting in a low grafting density.

  The number average molecular weight (Mn) of the graft chain can be measured by cleaving when the graft chain is bonded to the core fine particle through a relatively weak bond such as an ester bond. There are many cases where this is not possible, and there is no particular limitation. When it can measure by cleavage, the number average molecular weight is preferably from 500 to 1,000,000, more preferably from 1,000 to 500,000. When the number average molecular weight is less than 500, the dispersion stability of the core-shell fine particles is poor, and sedimentation is likely to occur. On the other hand, when larger than 1000000, the space | interval of a graft chain becomes coarse and the effect by the steric repulsion between core-shell fine particles becomes difficult to be acquired. The molecular weight of the graft chain controls the particle (colloid crystal) interval when, for example, a colloidal crystal is formed from the core-shell fine particles, and the number average molecular weight is appropriately selected depending on the desired interval. The molecular weight distribution (Mw / Mn) of the graft chain is preferably 1.0 to 1.6, and more preferably 1.0 to 1.3. When the molecular weight distribution is larger than 1.6, it is difficult to obtain a sufficient steric repulsion effect. When the molecular weight distribution is smaller than 1.0, it is difficult to produce such core-shell fine particles.

  Fine particles are taken out by performing an operation such as centrifugation after the polymerization, and if necessary, washed with an organic solvent and dried to produce core-shell fine particles. The core-shell fine particles obtained by such a production method have a spherical shape or a shape close thereto. About the core-shell fine particles, the average particle diameter measured by a dynamic light scattering method is 100 to 950 nm, preferably 110 to 900 nm, and more preferably 150 to 400 nm. Further, the CV value is 20% or less, preferably 15% or less, and more preferably 10 to 15%. In addition, the lower limit of the CV value is 0 in the case of monodispersion with finally uniform particle diameters. When the average particle size is smaller than 100 nm, it becomes difficult to control the interaction between the core and shell fine particles. When the average particle size is larger than 950 nm, it is difficult to take a regular arrangement due to the influence of sedimentation in colloidal crystallization, for example. . Further, the size of the core-shell fine particles described above is useful when a colloidal crystal is used as an optical element. When the CV value is larger than 20%, it is difficult to form a colloidal crystal because the particle size distribution is uneven.

Next, a method for producing an immobilized colloidal crystal will be described.
An immobilized colloidal crystal is obtained by dispersing core-shell fine particles in a monomer to obtain a colloidal crystal, and then irradiating with light to cure the monomer. The method for obtaining the colloidal crystal is not particularly limited. For example, the core-shell fine particles are mixed in the monomer, dispersed by sufficiently stirring, and allowed to stand for a certain period of time, thereby allowing mutual interaction between the fine particles in the monomer. By the action, colloidal crystals can be formed by regularly arranging fine particles. That is, it is considered that the steric repulsion of the graft chain prevents the fine particles from aggregating and suppresses the Brownian motion of the fine particles to form a crystal structure.

  The content of the core-shell fine particles is preferably 5 to 70% by mass and more preferably 10 to 50% by mass in the total amount of the core-shell fine particles and the monomer. When the content of the core-shell fine particles is more than 70% by mass, the viscosity becomes too high and colloidal crystallization hardly occurs. When the content is less than 5% by mass, the obtained immobilized colloidal crystals exhibit sufficient optical characteristics. Can not do.

  Monomers here include all of monofunctional monomers, polyfunctional monomers, etc., in addition to monomers other than the monomer (A) in the production of the core-shell fine particles. In order to ensure the mechanical strength of the immobilized colloidal crystal, one or more polyfunctional monomers containing 2 to 6 vinyl groups may be used in combination. Examples of such polyfunctional monomers include divinylbenzene, divinylnaphthalene, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, N, N′-methylenebisacrylamide, trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, etc. It is done. Moreover, in order to adjust the curing rate for immobilization, a photopolymerization initiator or a thermal polymerization initiator can be used in combination.

  The dispersion of the core-shell fine particles dispersed in the monomer may be cured after being applied to a substrate having a smooth surface such as glass and then cured after being allowed to stand in a glass cell. There is no particular limitation. In this case, a method according to a conventional method, for example, a spin coating method, a bar coating method, a spray coating method, a roll coating method or the like is employed. By using the organic solvent in combination, it is possible to improve the coating property and the adhesion to the substrate. The organic solvent is not particularly limited as long as it is a good solvent for the graft chain and volatilizes after coating. Examples thereof include alcohols, ketones, ethers, esters, cellosolves, aromatic compounds and the like. An organic solvent can be used individually or in combination of 2 or more types.

  The formed colloidal crystals are fixed by irradiating light to cure the monomer. As a light source for light irradiation, a low-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a carbon arc lamp, a xenon lamp, a metal halide lamp, or the like can be used. In this case, heating can be performed to accelerate curing in addition to light irradiation. The temperature is usually set to 10 to 150 ° C, preferably 20 to 100 ° C.

The actions and effects exhibited by the above embodiment will be described collectively below.
The core-shell fine particles of the present embodiment are constituted by covering the outer periphery of the core fine particles with a shell layer made of a graft chain having a photopolymerization initiating group (high density polymer brush). For this reason, for example, when obtaining an immobilized colloidal crystal, it is not necessary to add a new polymerization initiator, the polymerization can be carried out quickly by light irradiation, and the polymer is bonded to the core fine particles and integrated. Strength. Therefore, the core-shell fine particles can easily start polymerization, and the obtained cured product can exhibit sufficient mechanical strength. The core fine particles have a mean particle size of 100 to 950 nm and are in the order of submicrons (0.1 μm), and are monodispersed with a CV value representing a percentage of the standard deviation of the particle size with respect to the mean particle size of 20% or less. .

  -When the photopolymerization initiating group is a functional group represented by the chemical formula (1), the photopolymerization initiating group can be efficiently introduced into the graft chain, and an easy and sufficient radical is generated by light irradiation. be able to.

  In the method for producing core-shell fine particles, the core fine particles having a living radical polymerization initiating group, the monomer (A) having a polymerizable double bond and a photopolymerization initiating group, and a monomer other than the monomer (A) A shell layer is formed by graft polymerization with a monomer. For this reason, graft polymerization can be easily advanced by the living radical polymerization initiating group, and the photopolymerization initiating group can be introduced into the core-shell fine particles. Therefore, the core-shell fine particles can easily start polymerization by light irradiation using the photopolymerization initiating group, and the obtained cured product can exhibit sufficient mechanical strength.

  -Polymerizability can be improved because the polymerizable double bond of the monomer (A) is an acryloyl group, a methacryloyl group or a styryl group. In addition, since the photopolymerization initiating group is a functional group represented by the chemical formula (1), the photopolymerization initiating group can be efficiently introduced into the graft chain, and an easy and sufficient radical is generated by light irradiation. Can be made.

  In the method for producing an immobilized colloidal crystal, the core-shell fine particles are dispersed in a monomer to obtain a colloidal crystal, and then cured by irradiation with light. For this reason, the crystal particles can be immobilized and the mechanical strength of the immobilized colloidal crystal can be improved. The obtained immobilized colloidal crystal can be used as a color material, an optical functional material, an optical memory material, a sensor, a display device, or the like.

Hereinafter, although the said embodiment is described further more concretely by giving an Example and a comparative example, this invention is not limited to the range of these Examples. The average particle diameter, the CV value, the molecular weight of the graft chain, and the evaluation of the ordered arrangement structure of the colloidal crystal in each example were measured by the following methods.
1) Average particle diameter (nm) and CV value (%)
Core fine particles or core-shell fine particles were dispersed in tetrahydrofuran (THF) and measured by a dynamic light scattering method using a light scattering photometer ELS-8000 (manufactured by Otsuka Electronics Co., Ltd.).
2) Polymerization conversion rate (%)
The residual monomer was quantified and calculated by gas chromatography or liquid chromatography.
3) Molecular weight It calculated | required as a value of pullulan conversion by gel permeation chromatography (GPC).
4) Evaluation of ordered arrangement structure of colloidal crystal When the reflection peak wavelength occurred in the visible region, the color development and the sharpness of the colloidal crystal were visually confirmed.
Example 1
<Manufacture of core fine particle B1>
In a 500 mL four-necked flask equipped with a condenser, a thermometer, a stirrer, and a nitrogen inlet tube, 10.7 g of styrene (St), 55 mass% divinylbenzene (DVB55, purity 55 mass%, ethylvinylbenzene 42 mass%) Contained) 0.0866 g, p-sodium styrenesulfonate (NaSS) 0.0758 g and ion-exchanged water 350 g were added, stirred and mixed under a nitrogen stream, and heated to 75 ° C. Next, 0.0108 g of potassium persulfate (KPS) was added to the above reaction solution, a polymerization reaction was carried out at 75 ° C. for 7 hours, and then cooled to room temperature to obtain seed particles.

  Next, 0.541 g of sodium dodecylbenzenesulfonate (DBS) was added, and the mixture was stirred and mixed at room temperature under a nitrogen stream. To this was gradually added a solution obtained by dissolving 2.17 g of 2-bromoisobutyric acid 4-vinylphenyl ester and 0.108 g of 2,2′-azobisisobutyronitrile (AIBN) in 8.66 g of DVB55, The seed particles were allowed to absorb by stirring and mixing at room temperature for 1 hour.

Then, it heated up to 75 degreeC, and after performing the polymerization reaction at 75 degreeC for 14 hours, it cooled to room temperature. As a result, in all the polymerizable monomers, the polymerization conversion rate was 95% or more. Subsequently, the agglomerate was filtered off with a nylon mesh to obtain a fine particle dispersion. After salting out, it was filtered, washed with water and methanol, and then dried under reduced pressure to obtain core fine particles B1 containing an ATRP initiating group. The core fine particles B1 had an average particle size of 234 nm and a CV value of 12%.
<Manufacture of core-shell fine particles C1>
N, N-dimethylformamide (DMF) 5.11 g, t-butyl acrylate (t-BA) 9.18 g, 2- {2- [4- (2-hydroxy-2-methyl-propionyl) phenoxy] ethoxycarbonyloxy } 1.06 g of ethyl methacrylate (monomer A1), 0.0452 g of phenyl 2-bromoisobutyrate, and 0.0599 g of 1,1,4,7,10,10-hexamethyltriethylenetetramine were added and dissolved. 1.00 g of core fine particles B1 and 0.0373 g of copper bromide were added thereto, and the mixture was mixed and dispersed for 30 minutes with a homogenizer under a nitrogen atmosphere. The obtained dispersion was poured into a glass ampoule having an internal volume of 20 mL, purged with nitrogen, sealed, and polymerized at 90 ° C. for 15 hours. As a result, the polymerization conversion rates of t-BA and monomer A1 were 55.3% and 80.3%, respectively. THF (15 mL) was added to the contents, and fine particles were separated by a centrifuge. The obtained fine particles were washed with THF three times and dried under reduced pressure to obtain core-shell fine particles C1. The core-shell fine particles C1 had an average particle size of 290 nm and a CV value of 14%.

The graft chain was cut out from the core-shell fine particles C1 by treating the core-shell fine particles C1 with potassium hydroxide. The number average molecular weight (Mn) of the graft chain was 18300, and the molecular weight distribution (Mw / Mn) was 1.21. As a result of analyzing the composition of the graft chain by ¹ H-NMR, it was found to be a composition containing 13.8% by mass of monomer A1.
(Example 2)
<Manufacture of core-shell fine particles C2>
4.92 g of DMF, 7.77 g of methoxytriethylene glycol methacrylate (MTGA), 2.07 g of 2- [4- (2-hydroxy-2-methyl-propionyl) phenoxy] ethyl acrylate (monomer A2), 0.0452 g of phenyl 2-bromoisobutyrate and 0.0428 g of 1,1,4,7,10,10-hexamethyltriethylenetetraamine were mixed and dissolved. To this, 1.00 g of core fine particles B1 obtained in Example 1 and 0.0267 g of copper bromide were added, and mixed and dispersed with a homogenizer for 30 minutes in a nitrogen atmosphere. The obtained dispersion was poured into a glass ampoule having an internal volume of 20 mL, purged with nitrogen, sealed, and polymerized at 60 ° C. for 15 hours. The polymerization conversions of MTGA and monomer A2 were 65.5% and 85.3%, respectively. THF (15 mL) was added to the contents, and fine particles were separated by a centrifuge. The obtained fine particles were washed with THF three times and dried under reduced pressure to obtain core-shell fine particles C2. The average particle diameter of the core-shell fine particles C2 was 283 nm, and the CV value was 13%.

The graft chain was cut out from the core-shell fine particles C2 by treating the core-shell fine particles C2 with potassium hydroxide. Mn of the graft chain was 20500, and Mw / Mn was 1.29. As a result of analyzing the composition of the graft chain by ¹ H-NMR, it was found to be a composition containing 25.7% by mass of monomer A2.
(Example 3)
<Manufacture of core fine particle B2>
Stir 10.7g, DVB55 0.0866g, NaSS 0.1008g and ion exchange water 350g into a 500mL four-necked flask equipped with a condenser, thermometer, stirrer and nitrogen inlet tube, nitrogen stream The mixture was stirred and heated to 75 ° C. Next, 0.0108 g of KPS was added to the above reaction solution, a polymerization reaction was carried out at 75 ° C. for 7 hours, and then cooled to room temperature to obtain seed particles.

  To this, 0.650 g of DBS was added and stirred and mixed at room temperature under a nitrogen stream to obtain a mixed solution. DVB55 in 9.74 g with 2- (4′-hydroxy-2 ′, 2 ′, 6 ′, 6′-tetramethyl-1′-piperidinyloxy) -2- (3′-vinylphenyl) ethanol and 2 -(4'-hydroxy-2 ', 2', 6 ', 6'-tetramethyl-1'-piperidinyloxy) -2- (4'-vinylphenyl) ethanol m / p mixture (m / p 1.08 g of p ratio = 57/43) and 0.0541 g of 2,2′-azobisisobutyronitrile (AIBN) dissolved therein are gradually added to the above mixture and stirred and mixed at room temperature for 1 hour. As a result, the seed particles absorbed the seed particles.

Thereafter, the mixture was heated to 75 ° C., subjected to a polymerization reaction at 75 ° C. for 14 hours and then cooled to room temperature. As a result, in all the polymerizable monomers, the polymerization conversion rate was 95% or more. Subsequently, the agglomerate was filtered off with a nylon mesh to obtain a fine particle dispersion. After salting out, it was filtered off, washed with water and methanol, and then dried under reduced pressure to obtain core fine particles B2 containing alkoxyamine groups. The average particle size of the core fine particles B2 was 185 nm and the CV was 11%.
<Manufacture of core-shell fine particles C3>
3.67 g of DMF, 4.40 g of St, 1.20 g of t-BA, 2-hydroxy-2-methyl-1- {4- [2- (4-vinylbenzyloxy) ethoxy] phenyl} propane-1 -One (monomer A3) 0.5328 g, 2- (4′-hydroxy-2 ′, 2 ′, 6 ′, 6′-tetramethyl-1′-piperidinyloxy) -2-phenylethanol 0.0459 g was mixed and dissolved. 1.00 g of core fine particles B2 was added thereto, and the mixture was mixed and dispersed with a homogenizer for 30 minutes under a nitrogen atmosphere. The obtained dispersion was poured into a glass ampoule having an internal volume of 20 mL, purged with nitrogen, sealed, and polymerized at 115 ° C. for 15 hours. As a result, the polymerization conversion rates of St, t-BA, and monomer A3 were 32.7%, 31.2%, and 33.4%, respectively. 15 mL of THF was added to the contents, and fine particles were separated by centrifugation. The obtained fine particles were washed with THF three times and dried under reduced pressure to obtain core-shell fine particles C3. The core-shell fine particles C3 had an average particle size of 220 nm and a CV value of 14%.
Example 4
<Manufacture of core fine particle B3>
Stir 10.7 g, DVB55 0.0866 g, NaSS 0.0541 g and ion exchange water 350 g in a 500 mL four-necked flask equipped with a condenser, thermometer, stirrer and nitrogen inlet tube. The mixture was stirred and heated to 75 ° C. Next, 0.0108 g of KPS was added to the above reaction solution, a polymerization reaction was carried out at 75 ° C. for 7 hours, and then cooled to room temperature to obtain seed particles.

  DBS 0.541g was added to this, and it stirred and mixed under nitrogen stream at room temperature, and obtained the liquid mixture. DVB55 in 9.74 g with 2- (4′-hydroxy-2 ′, 2 ′, 6 ′, 6′-tetramethyl-1′-piperidinyloxy) -2- (3′-vinylphenyl) ethanol and 2 -(4'-hydroxy-2 ', 2', 6 ', 6'-tetramethyl-1'-piperidinyloxy) -2- (4'-vinylphenyl) ethanol m / p mixture (m / p (p ratio = 57/43) 1.08 g and 2,2′-azobisisobutyronitrile (AIBN) dissolved in 0.108 g are gradually added to the mixture, and the mixture is stirred at room temperature for 1 hour. This was absorbed by the seed particles.

It was heated to 75 ° C., subjected to a polymerization reaction at 75 ° C. for 14 hours, and then cooled to room temperature. As a result, the polymerization conversion rate was 95% or more for all polymerizable monomers. Subsequently, the agglomerate was filtered off with a nylon mesh to obtain a fine particle dispersion. The fine particle dispersion was salted out, filtered, washed with water and methanol, and then dried under reduced pressure to obtain core fine particles B3 containing alkoxyamine groups. The core fine particles B3 had an average particle size of 205 nm and a CV value of 13%.
<Manufacture of core-shell fine particles C4>
2.08 g of DMF, 1.87 g of St, 1.20 g of t-BA, 1.09 g of monomer A2, 2- (4′-hydroxy-2 ′, 2 ′, 6 ′, 6′-tetra 0.0459 g of methyl-1′-piperidinyloxy) -2-phenylethanol was mixed and dissolved. To this was added 1.00 g of core fine particles B3, and the mixture was dispersed by mixing for 30 minutes with a homogenizer under a nitrogen atmosphere. The obtained dispersion was poured into a glass ampoule having an internal volume of 20 mL, purged with nitrogen, sealed, and polymerized at 115 ° C. for 15 hours. As a result, the polymerization conversion rates of St, t-BA, and monomer A2 were 48.0%, 41.3%, and 40.5%, respectively. 15 mL of THF was added to the contents, and fine particles were separated by a centrifuge. The obtained fine particles were washed with THF three times and dried under reduced pressure to obtain core-shell fine particles C4. The core-shell fine particles C4 had an average particle size of 238 nm and a CV value of 15%.
(Comparative Example 1)
<Manufacture of core-shell fine particles C5>
3.49 g of DMF, 4.56 g of St, 2.41 g of t-BA, 2- (4′-hydroxy-2 ′, 2 ′, 6 ′, 6′-tetramethyl-1′-piperidinyloxy ) -2-Phenylethanol was mixed and dissolved in 0.0459 g. To this, 1.00 g of the core fine particles B2 obtained in Example 3 was added, and the mixture was mixed and dispersed for 30 minutes with a homogenizer under a nitrogen atmosphere. The obtained dispersion was poured into a glass ampoule having an internal volume of 20 mL, purged with nitrogen, sealed, and polymerized at 115 ° C. for 8 hours. As a result, the polymerization conversion rates of St and t-BA were 32.7% and 31.2%, respectively. 15 mL of THF was added to the contents, and fine particles were separated by a centrifuge. The obtained fine particles were washed with THF three times and dried under reduced pressure to obtain core-shell fine particles C5. The core-shell fine particles C5 had an average particle size of 218 nm and a CV value of 14%.
(Comparative Example 2)
<Manufacture of core-shell fine particles C6>
3.48 g of DMF, 4.56 g of St, 2.41 g of t-BA, 2- (4′-hydroxy-2 ′, 2 ′, 6 ′, 6′-tetramethyl-1′-piperidinyloxy ) -2-Phenylethanol was mixed and dissolved in 0.0459 g. To this was added 1.00 g of the core fine particles B3 obtained in Example 3, and the mixture was mixed and dispersed with a homogenizer for 30 minutes under a nitrogen atmosphere. The obtained dispersion was poured into a glass ampoule having an internal volume of 20 mL, purged with nitrogen, sealed, and polymerized at 115 ° C. for 15 hours. As a result, the polymerization conversion rates of St and t-BA were 42.7% and 41.7%, respectively. THF (15 mL) was added to the contents, and fine particles were separated by a centrifuge. The obtained fine particles were washed with THF three times and dried under reduced pressure to obtain core-shell fine particles C6. The core-shell fine particles C6 had an average particle size of 257 nm and a CV value of 14%.
<Immobilized colloidal crystals>
(Example 5)
0.750 g of core-shell fine particles C1, 0.675 g of methoxytriethylene glycol acrylate, 0.450 g of triethylene glycol diacrylate and 1.875 g of tetrahydrofuran (THF) were added, and the mixture was dispersed by mixing for 30 minutes with a homogenizer. . The obtained dispersion was applied onto a glass plate by a bar coating method (using bar coater No. 44), and tetrahydrofuran was volatilized in a desiccator. The colloidal crystal thus obtained had a red color (structural color by Bragg reflection).

Next, the colloidal crystal was irradiated with light using a high-pressure mercury lamp (manufactured by Harrison Toshiba Lighting Co., Ltd., UV irradiation device, Toscure 401) to polymerize the monomer, thereby obtaining an immobilized colloidal crystal. This immobilized colloidal crystal was a cured film exhibiting a green color.
(Example 6)
A colloidal crystal exhibiting a red color was obtained by following the procedure of Example 5 except that the core-shell fine particles C2 were used instead of the core-shell fine particles C1. The colloidal crystal was irradiated with light to polymerize the monomer to obtain an immobilized colloidal crystal. This immobilized colloidal crystal was a cured film exhibiting a green color.
(Example 7)
A colloidal crystal exhibiting a green color was obtained by operating according to Example 5 except that the core-shell fine particles C3 were used instead of the core-shell fine particles C1. The colloidal crystal was irradiated with light to polymerize the monomer to obtain an immobilized colloidal crystal. This immobilized colloidal crystal was a cured film having a blue color.
(Example 8)
A colloidal crystal exhibiting an orange color was obtained by operating according to Example 5 except that the core-shell fine particles C4 were used in place of the core-shell fine particles C1. The colloidal crystal was irradiated with light to polymerize the monomer to obtain an immobilized colloidal crystal. This immobilized colloidal crystal was a cured film exhibiting a green color.
(Comparative Example 3)
According to Example 5, except that core-shell fine particle C5 was used instead of core-shell fine particle C1, and 0.0338 g of Irgacure 2959 (Irgacure 2959, manufactured by Ciba Specialty Chemicals) was added as a photopolymerization initiator. The colloidal crystal which displayed green was obtained by operating. The colloidal crystal was irradiated with light to polymerize the monomer to obtain an immobilized colloidal crystal. The immobilized colloidal crystal was a white turbid cured film.
(Comparative Example 4)
According to Example 5, except that core-shell fine particle C6 was used instead of core-shell fine particle C1, and 0.0338 g of Irgacure 2959 (Irgacure 2959, manufactured by Ciba Specialty Chemicals) was added as a photopolymerization initiator. The colloidal crystals exhibiting a red color were obtained. The colloidal crystal was irradiated with light to polymerize the monomer to obtain an immobilized colloidal crystal. The immobilized colloidal crystal was a white turbid cured film.

  From the results of Examples 5 to 8, by including a photopolymerization initiating group in the graft chain, it was possible to obtain an immobilized colloidal crystal that was easily three-dimensionally regularly arranged only by light irradiation. On the other hand, from the results of Comparative Examples 3 and 4, when the photopolymerization initiating group was not included in the graft chain, the regular arrangement of the fine particles was destroyed, and the structural color development of the colloidal crystal could not be confirmed.

It should be noted that the present embodiment can be implemented with the following modifications.
-A plurality of monomers containing a living radical polymerization initiating group can be selected and used to adjust the graft polymerization initiating ability.

A plurality of monomers (A) having a polymerizable double bond and a photopolymerization initiating group can be selected and used to adjust the amount of photopolymerization initiating group introduced into the core-shell fine particles.
・ As cross-linkable monomers, use a combination of two or more types of bifunctional monomers having two vinyl groups and polyfunctional monomers having three or more vinyl groups to adjust the cross-linking density of the core fine particles. be able to.

Furthermore, the technical idea grasped from the embodiment will be described below.
The number average molecular weight (Mn) of the graft chain is 500 to 1,000,000, and the ratio (Mw / Mn) of the mass average molecular weight (Mw) to the number average molecular weight indicating the molecular weight distribution is 1.0 to 1.6. The core-shell fine particles according to claim 1 or 2, characterized in that In this case, in addition to the effect of the invention according to claim 1 or 2, when the core-shell fine particles are made into colloidal crystal fine particles, the fine particle spacing can be maintained and the dispersion stability of the fine particles can be maintained. Can be obtained.

  The method for producing core-shell fine particles according to claim 3 or 4, wherein the graft polymerization is performed in the presence of a polymerization initiator not bound to the core fine particles. When constituted in this way, in addition to the effect of the invention according to claim 3 or claim 4, a polymer other than the graft polymer can be formed, the graft chain can be formed uniformly, and the core Aggregation of fine particles can be suppressed.

  The method for producing core-shell fine particles according to claim 3 or 4, wherein the graft polymerization is performed in the presence of a catalyst comprising a transition metal complex. When comprised in this way, in addition to the effect of the invention which concerns on Claim 3 or Claim 4, graft polymerization can be accelerated | stimulated.

Claims (5)

Particles with an average particle diameter of 100 to 950 nm measured by a dynamic light scattering method, wherein the outer periphery of the core fine particles is coated with a shell layer made of a graft chain having a photopolymerization initiating group, and measured with a dynamic light scattering method. Core-shell fine particles characterized by having a CV value representing a percentage of diameter standard deviation of 20% or less. The core-shell fine particles according to claim 1, wherein the photopolymerization initiating group is a functional group represented by the following chemical formula (1).

The core fine particles having a living radical polymerization initiating group are graft-polymerized with a monomer (A) having a polymerizable double bond and a photopolymerization initiating group and a monomer other than the monomer (A) to form a shell. 3. The method for producing core-shell fine particles according to claim 1, wherein a layer is formed. The polymerizable double bond of the monomer (A) is an acryloyl group, a methacryloyl group or a styryl group, and the photopolymerization initiating group is a functional group represented by the following chemical formula (1). Item 4. A method for producing core-shell fine particles according to Item 3.

A method for producing an immobilized colloidal crystal, wherein the core-shell fine particles according to claim 1 or 2 are dispersed in a monomer to obtain a colloidal crystal and then cured by irradiation with light.