JP4982843B2 - Regularly arranged particle dispersion - Google Patents

Description

  The present invention relates to a dispersion containing particles that are self-assembled and can be regularly arranged three-dimensionally.

Colloidal particles are self-assembled in a liquid and regularly arranged three-dimensionally to exhibit a crystal structure (colloidal crystal). Recently, this colloidal crystal has attracted attention. Colloidal crystals are known in which particles having surface charges such as silica are dispersed in water. A strong electric double layer is formed on the silica surface in water, whereby each silica particle is stably crystallized.
The particle size of the particles used for the colloidal crystal is usually about several hundred to several thousand nm, and the plane spacing of the crystal corresponds to the wavelength of visible light. Therefore, the specific wavelength light is diffracted by so-called Bragg reflection and exhibits a predetermined color. . For this reason, it is expected that a colloidal crystal is applied to an optical element. For example, a technique for controlling the formation of a colloidal crystal by temperature has been proposed (for example, see Patent Document 1).

JP 11-319539 A

However, in the case of a dispersion in which colloidal particles are dispersed in water, since the viscosity of water is low, there is a problem that the colloidal crystal structure is easily destroyed when the dispersion is shaken. Further, since colloidal particles are crystallized by surface charge in water, which is a polar solvent, crystallization is hindered only by a small amount of impurity ions mixed in water. Furthermore, when water is used as a dispersion, it is easy to evaporate, and stability is difficult. When water is used as a dispersion, it is necessary to store the dispersion in a predetermined container in order to maintain the form of the dispersion, which is inconvenient to handle.
Accordingly, an object of the present invention is to provide an ordered particle dispersion which is excellent in stability of crystals and dispersions and can be made into a (semi) solid state.

The present inventors have solved the above-mentioned problems by paying attention to an ionic liquid (ionic liquid) that has non-volatility and is less affected by the mixing of impurity ions as a medium for forming a colloidal crystal. An ionic liquid is composed only of ions and has the characteristics that it is a liquid but has no vapor pressure (nonvolatile), has high heat resistance, and has a wide liquid temperature range.
However, since the entire medium of the ionic liquid is ionic, it cannot be expected to form crystals due to the charge between the colloidal particles. Therefore, the present inventors have succeeded in dispersing and crystallizing colloidal particles in the ionic liquid by using particles having compatibility with the ionic liquid and having an inner core.
That is, the regularly-arranged particle dispersion of the present invention includes a plurality of inner cores composed of spherical silica fine particles that are not substantially deformed in the ionic liquid, and a polymer that extends outward from the surface of the inner core and has compatibility with the ionic liquid. particles, and wherein the said ionic liquid for dispersing the particles, the polymer, acrylic acid, having the skeleton at least one member selected from the group consisting of methacrylic acid, and aryl groups, one or more linear alkyl carbon atoms And a polymer obtained by polymerizing a first monomer in which at least one selected from the group of a branched alkyl group having 3 or more carbon atoms is bonded to the skeleton , and the particles are self-organized in the ionic liquid. And can be regularly arranged three-dimensionally.

  According to the present invention, by using an ionic liquid as a medium, it is possible to obtain a regularly arranged particle dispersion that is excellent in stability of crystals and dispersions and can be made into a (semi) solid state.

  Hereinafter, embodiments of the present invention will be described. The regularly arranged particle dispersion according to the present invention is obtained by dispersing the following particles in an ionic liquid, and the particles are self-assembled in the ionic liquid and can be regularly arranged three-dimensionally.

<Particle>
The particles are compatible with the ionic liquid and include an inner core and a polymer extending outward from the surface of the inner core. FIG. 1 schematically shows the morphology of the particles. In this figure, a linear polymer 4 extends in a chestnut shape from the surface of the inner core 2 toward the outside, and constitutes a particle 10 as a whole.
(Inner core)
The inner core is not substantially deformed in the ionic liquid, and is regularly arranged three-dimensionally in the ionic liquid to show a crystal structure, and functions as a Bragg diffraction grating. The inner core may have a spherical shape or a shape close thereto, and the inner core preferably has a diameter of about 5 to 1000 nm. The diameter of the inner core is virtually unlimited as long as monodispersed colloidal particles (regularly arranged particles) are obtained. On the other hand, when the diameter of the inner core exceeds 1000 nm, the properties as colloidal particles are lost.
As the inner core, for example, inorganic fine particles such as spherical silica fine particles; polymer compound particles such as styrene beads and beads of styrene-divinylbenzene copolymer can be used. The polymer copolymer beads can be produced, for example, by emulsion polymerization and suspension polymerization.
Note that “substantially does not deform in the ionic liquid” means that the size and shape hardly change in the ionic liquid. Usually, such an inner core hardly elutes or swells in an ionic liquid.

(polymer)
The polymer is exposed outside the inner core and is compatible with the ionic liquid. For this reason, the particles as a whole are dispersed in the ionic liquid.
The presence or absence of compatibility with an ionic liquid can be determined by measuring the light transmittance of a solution obtained by dissolving a polymer (or the above-mentioned particle having a polymer added to the inner core) in the ionic liquid, and the polymer is in a phase-separated state. When the polymer is in a dissolved state, the liquid becomes transparent (translucent).
The polymer may always be completely compatible with the ionic liquid, or may be reversibly changed between a phase-separated state and a dissolved state with a predetermined physical stimulus as a boundary. In the latter case, the liquid becomes cloudy when the polymer is in a phase-separated state, and the liquid becomes transparent when the linear polymer is in a dissolved state. Examples of the physical stimulus include temperature, light, and electromagnetic waves. For example, when the temperature is a physical stimulus, the colloid solution may become more cloudy as the temperature rises, and the colloid solution may become transparent from the cloudy state.

The polymer is preferably a one-end-fixed linear polymer obtained by polymerizing the following monomers without using a crosslinking agent, but may be a polymer obtained by crosslinking polymerization.
The polymer has the following four types depending on the type of monomer to be polymerized.
(1) Polymer 1
The polymer 1 has at least one selected from the group of acrylic acid, methacrylic acid, lactone, glycol, and siloxane in the skeleton, and has an aryl group, a linear alkyl group having 1 or more carbon atoms, and a carbon number of 3 or more. It is obtained by polymerizing a monomer in which one or more members selected from the group of branched alkyl groups are bonded to the skeleton (hereinafter referred to as “first monomer or monomer C”).
The first monomer has a different affinity for the ionic liquid of the main chain (skeleton) and side chain (part bonded to the skeleton) in the monomer, and the resulting polymer undergoes a phase transition in the ionic liquid. Wake up and respond to physical stimuli.
The linear alkyl group preferably has 10 or more carbon atoms, and the branched alkyl group preferably has 10 or more carbon atoms.

It is preferable to use at least one selected from the group consisting of benzyl methacrylate, octadecyl methacrylate, octadecyl acrylate, and ε-caprolactone as the first monomer. In particular, as the first monomer, the chemical formula
Most preferably, benzyl methacrylate represented by the formula:

(2) Polymer 2
The polymer 2 is formed by copolymerizing the first monomer and the second monomer (or monomer B).
The second monomer has at least one selected from the group consisting of acrylic acid, methacrylic acid, acrylamide, methacrylamide, lactone, glycol, vinyl group, and siloxane in the skeleton, and a linear alkyl group and a branched alkyl group One or more selected from the group consisting of these are bonded to the skeleton.
Examples of the second monomer include methyl methacrylate, butyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, ethylene glycol, propylene glycol, dimethylsiloxane, and vinylpyrrolidone.
In the polymer 2, the carbon number of the linear alkyl group or branched alkyl group of the second monomer is smaller than the carbon number of the linear alkyl group or branched alkyl group of the first monomer. For example, when the straight-chain alkyl group of the first monomer has 5 carbon atoms, the straight-chain alkyl group or branched alkyl group of the second monomer has 4 or less carbon atoms.

Here, the phase separation temperature indicated by the linear polymer obtained by copolymerizing the first monomer and the second monomer without using the crosslinking agent is the phase indicated by the linear polymer obtained by polymerizing only the first monomer without using the crosslinking agent. Higher than the separation temperature. By using the second monomer having a higher phase separation temperature than the first monomer, the phase separation temperature of the linear polymer copolymerized with these can be increased, and the phase separation temperature of the whole polymer can be adjusted.
A preferred first monomer is benzyl methacrylate, and a second monomer is a short-chain methacrylic acid ester such as methyl methacrylate (MMA). There is no particular limitation.

(3) Polymer 3
The polymer 3 is formed by copolymerizing the first monomer and the third monomer (or monomer A).
The third monomer has at least one selected from the group consisting of acrylic acid, methacrylic acid, acrylamide, methacrylamide, lactone, glycol, vinyl group, and siloxane in the skeleton, and from the group of hydrogen, hydroxyl group, and heterocyclic amine. One or more selected are bonded to the skeleton, or an aryl group is bonded to a skeleton made of a vinyl group.
Examples of the third monomer include vinyl alcohol, tetrafluoroethylene, acrylamide, methacrylic acid, acrylic acid, 4-vinylpyridine, and styrene.

Here, the phase separation temperature indicated by the linear polymer obtained by copolymerizing the first monomer and the third monomer without using the crosslinking agent is the phase indicated by the linear polymer obtained by polymerizing only the first monomer without using the crosslinking agent. Below the separation temperature. By using the third monomer having a phase separation temperature lower than that of the first monomer, the phase separation temperature of the linear polymer copolymerized with these can be lowered, and the phase separation temperature can be adjusted.
A preferred first monomer is benzyl methacrylate, and a third monomer is a monomer having an aryl group such as styrene (St). The third monomer is not particularly limited as long as it is a constituent component of a polymer having a low affinity for the solvent.

(4) Polymer 4
The polymer 4 is formed by copolymerizing the second monomer and the third monomer.
In this case, a second monomer (which has a high affinity for the ionic liquid) that is compatible with the solvent (ionic liquid) regardless of the temperature and a polymer that is phase-separated with the solvent (ionic liquid) regardless of the temperature. By copolymerizing the constituent third monomer (having a low affinity for the ionic liquid), a portion having a different affinity for the ionic liquid was generated in the polymer, and thus, as in the case of the polymer 1, it was obtained. Polymers can respond to physical stimuli by causing phase transitions in ionic liquids.
The third monomer (monomer A) is completely phase separated from the ionic liquid, and the second monomer (monomer B) is completely compatible with the ionic liquid.

(5) Polymer 5
The polymer 5 is formed by polymerizing only the second monomer. In this case, a polymer compatible with the solvent (ionic liquid) regardless of the temperature is formed.

  In the present invention, for example, the polymer 1 includes a polymer obtained by polymerizing a plurality of monomers as long as it is within the range defined by the first monomer. The same applies to other polymers.

<Production of particles>
The particles can be obtained, for example, by fixing a treatment agent for bonding the inner core and the polymer to the surface of the inner core and then graft polymerizing the treatment agent to the treatment agent. In this case, a polymer in which a linear polymer extends from the inner core in a radial (bamboo chestnut) shape is usually obtained.
When the inner core is inorganic particles, an organic silane compound such as a silane coupling agent can be suitably used as the treatment agent. Specific examples of the treating agent include (3- (2-bromo-2-methyl) propyl) dimethylethoxysilane (BIDS).
As the graft polymerization of the polymer, it is preferable to use living radical polymerization in which a polymer having a uniform length (narrow distribution of length) is obtained. In the case of living radical polymerization, the treatment agent serves as an initiator, and a transition metal complex such as copper (I) bromide and the monomer are added to carry out the polymerization.
The method of living radical polymerization of monomers on the surface of silica particles is described in, for example, literature (J. Am. Chem. Soc. 2001, 123, 7497-7505, Macromolecules 2005, 38, 2137-2142).
The length (molecular weight) of the polymer can be adjusted by changing the polymerization starting point and the polymerization time.

<Ionic liquid>
An ionic liquid (ionic liquid) is composed only of ions, is a liquid, has no vapor pressure (nonvolatile), has high heat resistance, has nonflammability, and nonvolatility. In the present invention, the melting point of the ionic liquid is preferably 100 ° C. or lower, more preferably room temperature or lower.

The polarity parameter E _T (30) of the ionic liquid is preferably 48.2 to 52.4. Since the ionic liquid is an ionic conductor, the dielectric loss is large and it is difficult to estimate the dielectric constant. Therefore, it is preferable that the polarity parameter E _T (30) of the solvent using solvatochromism is used as an index of the ionic liquid.
Here, an ionic liquid having an E _T (30) of less than 48.2 and an ionic liquid having an E _T (30) of more than 52.4 are difficult to obtain, and thus are in the above range.

E _T (30) is the chemical formula
1 was dissolved in a solvent (ionic liquid), and the maximum absorption wavelength λmax was measured.
E _T (30) = 28591 / λmax (1)
Can be calculated from Since there is a very good correlation between E _T (30) and the quantified value (acceptor number) of the Lewis acidity of the solvent, E _T (30) is considered to represent the Lewis acidity of the ionic liquid. It is done.

The ionic liquid is not particularly limited. For example, an ammonium structure, an imidazolium structure, a pyridinium structure, a pyrrolidinium structure, a sulfonium structure, a phosphonium structure, or the like can be used as a cation, and a sulfonimide structure or a phosphate structure (hexafluorophosphate) can be used as an anion. Etc.), borate structure (tetrafluoroborate), trifluoroacetic acid, trifluorosulfuric acid, acetic acid, halogen-based anions (Cl, Br, I), chloroaluminate, thiocyanate, and the like. In particular,
Chemical formula
1-ethyl-3-methylimidazolium represented by the following formula: a cation and bis (trifluoromethanesulfone) imide ((CF ₃ SO ₂ ) ₂ N ⁻ ) as an anion (EMITFSI, melting point −18 ° C., E _T (30) = 52.2) and / or 1-ethyl-3-methylimidazolium as a cation and chlorine ion as an anion (melting point: 87 ° C.) can be preferably used.
From the value of E _T (30), the Lewis acidity of EMITFSI is higher than DMSO and DMF, which are non-aqueous polar solvents, and is considered to be comparable to alcohols.

<Dispersion of particles in ionic liquid>
The particles may be dispersed as they are in the ionic liquid, but in this case, it may take time to dissolve the particles in the ionic liquid. Therefore, it is preferable to use a co-solvent (for example, THF) of particles and ionic liquid. The cosolvent can be removed by dissolving the particles in an ionic liquid and then heating under reduced pressure.

<Particle crystallization>
The obtained dispersion exhibits a predetermined color as the dispersed particles crystallize. The wavelength of the diffracted light by the crystal varies depending on the particle diameter of the inner core, the length or molecular weight of the polymer (which affects the diameter of the entire particle), the mixing ratio of the particles and the ionic liquid, and the like. The larger the inner core particle size, the greater the polymer length (molecular weight), and the greater the blending ratio of the ionic liquid to the particles, the more the diffracted light tends to redshift.
Since the diffracted light is red-shifted as the blending ratio of the ionic liquid to the particles increases, it is considered that the particles are crystallized non-closely in the ionic liquid.
FIG. 2 schematically shows the arrangement of adjacent particles in the ionic liquid. In this figure, adjacent particles 10 are arranged via ionic liquid molecules 20, and as the blending ratio of the particles 10 increases, the distance between the particles 10 decreases and approaches the distance at which the polymers 4 of each particle 10 repel each other. It is considered possible.

<Dispersion form>
The form of the dispersion can be solid, semi-solid (paste-like, grease-like) or viscous liquid. The smaller the inner core particle size, the longer the polymer length (molecular weight), and the smaller the blending ratio of the ionic liquid to the particles, the easier the dispersion becomes solid. The parameter that determines the material form of the colloidal crystal is considered to be the blending ratio of the graft polymer present in the colloidal crystal. This is because if the particle size of the inner core is reduced or the blending ratio of the ionic liquid to the particles is small, the ratio of the polymer and the ionic liquid in contact with the ionic liquid is relatively high, and the viscosity of the dispersion is increased. It is done. Further, it is considered that as the polymer length increases, the viscosity of the dispersion increases because the relative polymer content increases.

<Dispersion conductivity>
In the dispersion, particles are regularly arranged three-dimensionally, and an ionic liquid exists between the particles, so that an ion path regularly arranged three-dimensionally is formed through the ionic liquid. Therefore, if this dispersion is solidified as described above, a solid electrolyte having an ion path whose arrangement is controlled in three dimensions can be obtained.

Since the dispersion of the present invention diffracts light having a predetermined wavelength as described above, it can be applied as a colorimetric sensor, display element, color material, or photonic crystal.
Moreover, it is applicable to the solid electrolyte of a solar cell or a fuel cell in which charge transport (ion transport) accompanied by an exchange reaction is important.
In addition, the dispersion of the present invention is superior in long-term stability of the crystal and the dispersion compared to conventional colloidal crystals using water as a medium, and can be handled by increasing the area by making the dispersion semi-solid. Becomes easy.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples. In addition, unless otherwise indicated,% shows the mass%.

1. Preparation of ionic liquid (1-ethyl-3-methylimidazolium bistrifluoromethanesulfonimide; EMImTFSI)
Cl ^- cause quaternization reaction of methylimidazole and ethyl bromide, 1-ethyl-3-methyl imidazolium -Br (EMImBr). The resulting EMImBr was subjected to an anion exchange reaction with LiTFSI (Li-trifluoromethanesulfone) imide (Li (CF ₃ SO ₂ ) ₂ N) to prepare 1-ethyl-3-methylimidazolium bistrifluoromethanesulfonimide (EMImTFSI) did.

2. Manufacture of particles (polymethyl methacrylate-grafted monodispersed silica fine particles) Monodispersed silica fine particles are used as the inner core, and a treatment agent for bonding the inner core and the polymer is fixed on the silica surface, and then the polymer is attached to the treatment agent. Were graft polymerized to produce particles.

(2-1) Synthesis of treating agent (3- (2-bromo-2-methyl) propyl) dimethylethoxysilane (BIDS), which is a treating agent, was synthesized as follows.
First, allyl 2-bromoisobutyrate as a precursor was synthesized as follows.
The N ₂ -substituted 500 mL three-necked flask was brought to 0 ° C. with an ice bath. Thereafter, 300 mL of dehydrated dichloromethane, 6.00 mL of allyl alcohol, and 13 mL of triethylamine were added to the flask and cooled until the temperature reached 0 ° C. Using a dropping funnel, 25 g of 2-isobutyl bromide was stirred while slowly dropping into the flask. Subsequently, after stirring at 0 ° C. for 3 hours and at room temperature for 15 hours, a liquid separation operation (3 times) was performed with 200 mL of deionized water to remove ammonium bromide as a double product. The organic phase was recovered, and dichloromethane as a solvent was removed by evaporation, followed by purification by distillation under reduced pressure to obtain 17.3 g of allyl 2-bromoisobutyrate.
Next, 10.6 g of allyl 2-bromoisobutyrate, 2 mL of dehydrated xylene, and 400 μL of a 0.1 mol / L Pt (0) catalyst xylene solution were added to a N ₂ -substituted 100 mL three-necked flask. While 10.0 g of dimethylethoxysilane was slowly dropped using a dropping funnel, the mixture was stirred at room temperature for 24 hours. The progress of the reaction was carried out by confirming the disappearance of the raw material peak of allyl 2-bromoisobutyrate as a raw material by gas chromatography. Thereafter, the unreacted raw material and the solvent are removed under reduced pressure, and the target product (3- (2-bromo-2-methyl) propyl) dimethylethoxysilane (BIDS) is obtained by distillation under reduced pressure (1-2 mmHg) at 140 to 150 ° C. ) 7.21 g was obtained.

(2-2) Immobilization of treatment agent (BIDS) to inner core (monodispersed silica fine particles) 6 g of monodispersed silica fine particles (Nippon Catalyst) having a particle size of 100 nm and 200 nm were dispersed in 300 mL of tetrahydrofuran, It put into a 500 mL three necked flask. Under reflux at 85 ° C., 1.0 mL of (3- (2-bromo-2-methyl) propyl) dimethylethoxysilane was slowly added dropwise to the flask with a syringe and stirred. Thereafter, stirring was continued at 85 ° C. under reflux for 24 hours. Fine particles collected by centrifugation (5000 rpm, 10 min) and redispersed in tetrahydrofuran were repeated three times to purify silica fine particles with BIDS fixed on the surface.

(2-3) Production of particles (surface initiation atom transfer radical polymerization of polymer to silica fine particles)
2 g of the above-mentioned BIDS-immobilized silica fine particles were dispersed in 10.0 g of methyl methacrylate as a monomer and transferred to a 100 mL three-necked flask containing 0.022 g of copper (I) bromide. Thereto were added 0.124 g of 4,4′-dinonyl-2,2′-dipyridyl and 6.00 mL of dehydrated xylene, and immediately, freeze degassing and N ₂ substitution were repeated three times to remove dissolved oxygen in the solution. Thereafter, the temperature was returned to room temperature, 2.2 μL of ethyl 2-bromoisobutyrate was added, and the mixture was immediately immersed in an oil bath set at 75 ° C., and polymerization was started while stirring. After 24 hours, the reaction was stopped, and the solution was added dropwise to methanol for reprecipitation to obtain polymethyl methacrylate-grafted silica fine particles and free polymethyl methacrylate, which were the target products. Thereafter, these were dissolved and dispersed in tetrahydrofuran, and free polymethyl methacrylate was separated by centrifugation. The process of dissolving and dispersing the obtained polymethyl methacrylate grafted silica fine particles in tetrahydrofuran was repeated three times, and the particles were collected by centrifugation, reprecipitated with methanol again to purify the particles.

3. Preparation of regularly arranged particle dispersion (dispersion of particles in ionic liquid)
1 g of the above particles and 10 g of tetrahydrofuran are mixed well in 3 g of the ionic liquid (EMImTFSI), and the tetrahydrofuran is removed at 60 ° C. under reduced pressure to give a paste-like substance exhibiting a green color (regularly arranged particle dispersion, EMImTFSI The particle concentration was 25 wt%).

<Evaluation>
(1) Measurement of polymer molecular weight The molecular weight of polymethyl methacrylate (PMMA) polymerized into silica fine particles was measured. Specifically, after removing the silica component of the inner core with a 46% HF aqueous solution, the molecular weight of the cut polymer was measured by gel permeation chromatography (GPC) manufactured by Shimadzu Corporation.

(2) Thermogravimetric measurement of colloidal crystal The thermogravimetricity of the obtained ordered array particle dispersion was measured. The weight loss was measured at a temperature increase rate of 10 ° C./min in a temperature range from room temperature to 550 ° C. in a nitrogen atmosphere using a Seiko thermogravimetric analyzer (TG measurement). The measurement results are shown in FIG. In the figure, symbol a represents a case where the polymer (PMMA graft) has a molecular weight of 41000 and an inner core (monodispersed silica fine particle) particle size of 200 nm, and symbol b represents a particle having a PMMA graft molecular weight of 42000 and silica particle size of 100 nm. In this case, the symbol c is a case of a particle having a PMMA graft molecular weight of 72000 and a silica particle size of 100 nm. The symbol x represents the case of ungrafted silica (particle size 100 nm), and the symbol y represents the case where the treatment agent (BIDS) was immobilized on the ungrafted silica (particle size 100 nm).
Compared with the sample containing only silica fine particles, the weight loss was observed in the sample obtained by graft polymerizing the silica fine particles, and it was confirmed that the polymer was polymerized into silica fine particles.

(2) Material Form of Colloidal Crystal The material form of the obtained ordered array particle dispersion (colloidal crystal) was examined. To investigate the material form, the eggplant flask containing the colloidal crystals was inverted and the fluidity of the colloidal crystals was observed. When it showed fluidity, it was liquid, and when it did not show fluidity, it was solid or pasty. The fluidity was confirmed by the test tube inversion method, and the solid and paste were determined by examining the viscoelasticity of the colloidal crystals with a medicine spoon and the like, and when having viscoelasticity, the paste was formed.
When particles with a graft molecular weight of 72000 and a silica particle size of 100 nm were dispersed in EMImTFSI at 50 wt%, it became a solid, but when the particle concentration was 33 wt%, it did not show fluidity but deformed in response to stress It became.

(3) Optical characteristics of colloidal crystal (regularly arranged particle dispersion) The diffracted light of a specific wavelength when the obtained ordered arrayed particle dispersion was irradiated with all light was measured by reflection spectrum measurement. Measurement was performed using a tungsten halogen lamp as a light source (Ocean Optics) and an optical fiber probe (Ocean Optics) to which a light source and a detector (Ocean Optics) were connected.
The obtained results are shown in FIG. Symbols a to c in the figure correspond to the sample of the thermal measurement (FIG. 3). In the case of sample b, which was a colloidal crystal in which the particle concentration in EMImTFSI was regulated to 25 wt%, a diffraction peak was shown at 500 nm. In the case of sample c, the diffracted light was red-shifted to 550 nm (green light). In the case of sample a, a diffraction peak was shown at 800 nm. From this, it was found that the wavelength of the diffracted light can be controlled by changing the molecular weight of the particle polymer (graft polymer) and the inner core (silica core) particle size.
Further, in the sample c, when the particle concentration in EMImTFSI was changed to 33.3 wt% and the diffracted light was measured in the same manner, it turned blue. From this, it was found that the wavelength of the diffracted light can be controlled by changing the blending ratio of the ionic liquid and the particles.

(4) Electrochemical characteristics of colloidal crystal The ionic conductivity of each colloidal crystal when the particles having the above-mentioned symbols a to c were used was measured by the AC impedance method. The measurement was carried out using a sealed coin cell containing a stainless steel electrode as the measurement cell, the measurement temperature was 0 ° C. to 80 ° C., the frequency range was 500 kHz to 1 Hz, and the applied voltage was 10 mV. In addition, the code | symbol z in a figure is a case where only an ionic liquid (EMImTFSI), and the code | symbol p is a case where a linear polymer (PMMA) is disperse | distributed to EMImTFSI (a silica particle is not included).
The obtained results are shown in FIG. It was found that colloidal crystals had higher ionic conductivity than PMMA dispersed in ionic liquid.

It is a figure which shows the form of particle | grains typically. It is a figure which shows typically the arrangement | positioning state of the adjacent particle | grains in an ionic liquid. It is a figure which shows the spectrum by the heat measurement of a colloid crystal. It is a figure which shows the spectrum of the diffracted light of a colloidal crystal. It is a figure which shows the ionic conductivity of a colloidal crystal.

Explanation of symbols

2 inner core 4 polymer 10 particles 20 ionic liquid

Claims (1)

An inner core composed of spherical silica fine particles that do not substantially deform in an ionic liquid, a plurality of particles including a polymer extending outward from the surface of the inner core and having compatibility with the ionic liquid, and the ionic liquid in which the particles are dispersed Including
The polymer, acrylic acid, having the skeleton at least one member selected from the group consisting of methacrylic acid, and aryl groups, one or more straight-chain alkyl group having a carbon number, and from the group having 3 or more branched alkyl group having a carbon a polymer in which one or more is formed by polymerizing the first monomer attached to the backbone chosen,
The regularly arranged particle dispersion, wherein the particles are self-organized in the ionic liquid and can be regularly arranged three-dimensionally.