JP2005097355A - Spherical polymer particle and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide polymer particles each of whose surfaces is composed of a plurality of hemispherical concavities and to provide a method for producing the same. <P>SOLUTION: The polymer particles have each a surface composed of a plurality of hemispherical concavities. The method for producing the polymer particles comprises the step (a) of dispersing amphiphilic particles capable of forming micelle-like particles in an organic solvent in which a polymer is dissolved, the step (b) of mixing the dispersion obtained in the step (a) with water to form micelle-like particles in which the polymer and the organic solvent are enclosed with the aid of the amphiphilic particles, the step (c) of removing the organic solvent from the micelle-like particles obtained in the step (b), and the step (d) of removing the amphiphilic particles from the micelle-like particles. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to spherical polymer particles and a method for producing the same. More specifically, the present invention relates to a spherical polymer particle having a surface formed by a plurality of hemispherical concave surfaces and a method for producing the same.

Regardless of the organic or inorganic compound, the physical properties of the fine particle material are greatly affected by the size, shape, internal structure, surface structure, etc. Therefore, the fine particle synthesis technology is free to control these characteristics. So far, many chemical or physical synthesis techniques using liquid phases have been developed. Among them, a system (emulsion) in which droplets are dispersed in an incompatible liquid or a molecular surfactant. In a system (microemulsion) in which micelles are made, the method of preparing microparticles using the internal space of droplets or micelles is notable because it can synthesize organic compounds such as polymer particles with controlled size (See Non-Patent Documents 1 and 2). However, although it is possible to synthesize particles having an arbitrary size by a combination of these methods, the shape of each particle is often a perfect sphere with no irregularities, and the shape or surface structure can be manipulated freely. That has not been achieved.
Langmur, 2003, 19, p.4817-4824 J. Am. Chem. Soc., 2003, 125, p.8838-8840

  An object of the present invention is to provide spherical polymer particles having a surface formed by a plurality of hemispherical concave surfaces and a method for producing the same.

The present invention
[1] Spherical polymer particles having a surface formed by a plurality of hemispherical concave surfaces,
[2] The spherical polymer particles according to [1], wherein the spherical polymer particles are made of polystyrene, and [3] (a) amphiphilic particles capable of forming micellar particles in an organic solvent in which the polymer is dissolved. Dispersing step,
(B) The step of mixing the dispersion obtained in step (a) with water to form micellar particles in which the polymer and organic solvent are taken into the interior by amphiphilic particles,
(C) removing the organic solvent contained in the micellar particles obtained in step (b) to solidify the polymer in the micelle particles, and (d) amphiphilic particles from the micelle particles. The present invention relates to a method for producing spherical polymer particles according to [1] or [2], which comprises a step of removing.

  According to the present invention, spherical polymer particles having a surface formed by a plurality of hemispherical concave surfaces are provided. Such spherical polymer particles can be easily manufactured using the internal space of micellar particles formed by amphiphilic particles, and their characteristic surface structure is expected to be applied in various fields. It is what is done.

  The spherical polymer particles of the present invention are characterized in that the surface is formed by a plurality of hemispherical concave surfaces, and are formed by droplets in an emulsion or molecular surfactants in a microemulsion. Compared to conventional spherical particles without irregularities obtained by using the inner space of micelles, the catalyst or catalyst carrier having a specific surface active point, adsorption point, or other functional material has a larger surface area. It is expected to function more effectively as a carrier and the like.

  In the present invention, the spherical polymer particles having a surface formed by "a plurality of" hemispherical concave surfaces means that there are a plurality of portions having a hemispherical concave surface on the surface of the spherical polymer particles, and the number is Since it differs depending on the size of the concave surface, etc., it cannot be defined unconditionally, but it is preferable that there are a large number of concave surfaces to such an extent that a portion having a hemispherical concave surface is formed over the entire surface of the spherical polymer particles. “Hemispherical concave surface” refers to a concave surface having a hemispherical shape or a curved surface close to a hemisphere. In addition, since the “spherical” polymer particles of the present invention have a plurality of concave surfaces on the surface, they are not strictly “spherical”, but show a nearly spherical shape as a whole. .

In the present invention, for example, spherical polymer particles use micelle-like particles formed of amphiphilic particles as a template, and a method of forming polymer particles in the internal space thereof, for example,
(A) a step of dispersing amphiphilic particles capable of forming micellar particles in an organic solvent in which a polymer is dissolved;
(B) The step of mixing the dispersion obtained in step (a) with water to form micellar particles in which the polymer and organic solvent are taken into the interior by amphiphilic particles,
(C) removing the organic solvent contained in the micellar particles obtained in step (b) to solidify the polymer in the micelle particles, and (d) amphiphilic particles from the micelle particles. It is obtained by a method having a step of removing.

  In the step (a), amphiphilic particles capable of forming micellar particles are dispersed in an organic solvent in which the polymer is dissolved.

  As the polymer used in the step (a), that is, the polymer constituting the spherical polymer particle of the present invention, various polymers such as polystyrene, polymethyl methacrylate, polyethylene and the like can be used. From the viewpoints of colorability, colorability, electrical insulation, and ease of modification, polystyrene is preferred.

  The organic solvent for dissolving the polymer may be appropriately selected depending on the type of polymer to be used, and is not particularly limited, and examples thereof include toluene, benzene, and cyclohexane.

  The amount of the organic solvent used depends on the solubility of the polymer, but is preferably about 300 to 2000 parts by weight, more preferably 600 to 1200 parts by weight with respect to 100 parts by weight of the polymer.

  In the present invention, the amphiphilic particles capable of forming micellar particles are particles having a hydrophilic portion and a lipophilic portion at the same time on the surface of one particle, and the hydrophilic portion and the lipophilic portion are These are particles that exist in a localized manner and can form micellar particles so that the surfactant forms spherical micelles.

  On the surface of the amphiphilic particles, a hydrophilic portion is dispersed on the lipophilic surface even if the lipophilic portion is dispersed on the hydrophilic surface within a range in which micelle-like particles can be formed. The hydrophilic portion and the hydrophilic portion may be present separately, but in the present invention, the hydrophilic portion and the lipophilic portion are present in half, and the liquid / liquid interface is When added to the heterogeneous system to be formed, the particles arranged closer to the liquid / liquid interface (heterophasic interface particles) are preferable because micelle-like particles can be easily formed.

  On the surface of the amphiphilic particles, as long as the hydrophilic portion shows hydrophilicity, all of them may show the same hydrophilicity, or may show different hydrophilicity. Similarly, as long as a lipophilic part shows lipophilicity, all may show the same lipophilicity, and may show different lipophilicity.

  The amphiphilic particles suitably used in the present invention, for example, after aggregating particles having hydrophilicity or lipophilicity, on the surface of the obtained aggregated particles, when hydrophilic particles are used, the lipophilic part is When lipophilic particles are used, the hydrophilic portion can be obtained by a method of introducing. For example, when a lipophilic portion is introduced into the hydrophilic particles by a lipophilic group by such a method, as shown in the schematic diagram of FIG. 1A, only the surface portion exposed on the outermost surface of the aggregated particles is lipophilic. An amphiphilic particle 1 in which the group 2 is introduced is obtained. The amphiphilic particles 1 in which the hydrophilic part 3 and the lipophilic part 4 are localized exist, when the concentration in the aqueous phase 5 reaches a certain level, the hydrophilic part 3 faces outward and the lipophilic part 4 faces inward. The oil phase 6 is collected inside to form micellar particles 7 as shown in the schematic diagram of FIG.

  The ratio between the hydrophilic portion and the lipophilic portion is not particularly limited, and the hydrophilic strength of the hydrophilic portion, the lipophilic strength of the lipophilic portion, the type of liquid phase to which the amphiphilic particles are added, etc. Is adjusted as appropriate.

  The hydrophilic or lipophilic particles used for the amphiphilic particles are appropriately selected depending on the type of polymer constituting the spherical polymer particles of the present invention. Examples of the hydrophilic particles include silica, zeolite, titanium oxide, and alumina. Among these, silica is preferable because the particles have high sphericity and are easy to remove after the formation of micellar particles.

  As a method for introducing a lipophilic part into the surface of the hydrophilic particle, a method in which a part of the surface of the hydrophilic particle is alkylsilylated with an alkylsilylating agent is preferable. The number of carbons in the alkyl group of the alkyl silylating agent and the amount of the alkyl silylating agent used are not particularly limited. The hydrophilic strength of the hydrophilic portion to be introduced, the type of liquid phase to which amphiphilic particles are added, etc. Can be adjusted as appropriate.

  For example, when the silica particles are alkylsilylated to produce the amphiphilic particles used in the present invention, after adding water or the like to silica in advance and aggregating, the surface of the obtained agglomerated particles is alkylated. By silylated, silica particles in which only the portion exposed on the outermost surface of the aggregated particles is alkylsilylated can be obtained. In this case, by performing alkylsilylation in the presence of a catalyst such as triethylamine, the hydroxyl group of silica can be activated and the reaction with the alkylsilylating agent can be promoted.

  Examples of the lipophilic particles used for the amphiphilic particles include polystyrene and polymethyl methacrylate.

  As a method for introducing a hydrophilic portion on the surface of the lipophilic particle, a part of the surface of the lipophilic particle is coated with gold fine particles by vapor deposition, and an aminoalkylthiol having an amino group as a hydrophilic group is selectively applied to the gold fine particles. And the like.

  The amount of amphiphilic particles used is not particularly limited as long as the particles do not cause aggregation, and is usually used in step (a) with respect to 100 parts by weight of the organic solvent in which the polymer is dissolved. 0.5 to 5 parts by weight is preferable, and 1 to 1.5 parts by weight is more preferable.

  The method for dispersing the amphiphilic particles in the organic solvent in which the polymer is dissolved is not particularly limited. However, when the amphiphilic particles form micelle-like particles in the subsequent step (b), the polymer is incorporated into the micelle-like particles. It is preferable to disperse the amphiphilic particles uniformly by sonication or the like so that the particles can be easily taken in.

  In the step (b), the dispersion obtained in the step (a) is mixed with water to form micellar particles in which the polymer and the organic solvent are taken into the interior by the amphiphilic particles.

  The amount of water used is not particularly limited as long as the amphiphilic particles are in such a concentration that the micelle-like particles can be formed on the inner surface of the lipophilic part, but usually 100 parts by weight of the dispersion obtained in step (a). The amount is preferably about 100 to 1000 parts by weight, more preferably 200 to 500 parts by weight.

  From the viewpoint of promoting the formation of micellar particles after mixing the dispersion with water, it is preferable to perform ultrasonic treatment. Furthermore, the ultrasonic treatment is preferably performed while cooling the mixed solution with an ice bath or the like from the viewpoint of avoiding unnecessary heating due to the treatment.

  In the step (c), the organic solvent contained in the micellar particles obtained in the step (b) is removed, and the polymer in the micelle particles is solidified.

  The method for removing the organic solvent contained in the micellar particles is not particularly limited. For example, the mixed solution containing the micelle particles obtained in the step (b) is separated into an oil phase and an aqueous phase by standing, Since the micelle particles move into the aqueous phase, the oil phase is removed, and further, the micelle particles can be recovered by removing the water, but at this time, by evaporating the water by heating, Simultaneously with the removal of water, the organic solvent in the micellar particles can also be removed, and the polymer can be solidified.

  In the step (d), amphiphilic particles are removed from the micellar particles.

  The method for removing the amphiphilic particles can be appropriately selected depending on the type of the amphiphilic particles, and is not particularly limited. For example, when silica is used as the amphiphilic particles, the silica is hydrofluoric acid aqueous solution or the like. It can be dissolved and removed.

  When the amphiphilic particles are removed from the micellar particles, spherical polymer particles having a structure that partially reflects the shape of the amphiphilic particles, that is, a surface formed by a plurality of hemispherical concave surfaces, are obtained. .

  Furthermore, in the present invention, the spherical polymer particles of the present invention can be obtained by a method in which the polymer monomer is polymerized in the micellar particles in addition to the method in which the polymer is once dissolved and then solidified in the micellar particles as described above. You can also get According to this method, for example, it is possible to produce spherical particles of crosslinked polystyrene by copolymerizing styrene and divinylbenzene in micellar particles. The crosslinked polystyrene particles are used as a carrier for an ion exchange resin. It can also be applied to gel filtration gels.

  According to the present invention, spherical polymer particles having a particle size of about 1 to 10 μm can be obtained. According to the method of the present invention, the size of the particles and their concave surfaces can be adjusted by changing the blending ratio of the polymer, organic solvent and water and the size of the amphiphilic particles. It is also possible to obtain spherical polymer particles having a difficult size, for example, a size exceeding 5 μm.

  Hereinafter, the present invention will be described in more detail based on examples. However, the present invention is not limited to the examples.

Production Example of Amphiphilic Particles 0.3 g of water was added to 2.5 g of silica (Seahoster (KEP-30) manufactured by Nippon Shokubai Co., Ltd., average particle size: 0.3 μm). The obtained mixed liquid was suspended in 50 ml of toluene in which 2.5 mmol of alkylsilylating agent [octadecyltrimethoxysilane (OTS)] was dissolved, and 2.5 mmol of triethylamine was added. The suspension was stirred for 10 minutes, then centrifuged, and dried in vacuum at room temperature for 3 hours to obtain silica particles in which part of the particle surface was modified with long-chain alkyl groups.

  Further, the obtained silica particles were dispersed in a two-phase system composed of a toluene phase and an aqueous phase, and only the particles existing in the vicinity of the interface were extracted and purified. The obtained particles are referred to as amphiphilic particles A.

Preparation Example of Hydrophobic Particles Suspension in 50 ml of toluene in which 2.5 mmol of alkylsilylating agent [octadecyltrimethoxysilane (OTS)] was dissolved without adding silica to water, followed by 2.5% of triethylamine 2.5 Millimol was added. The suspension was stirred for 10 minutes, then centrifuged and dried in vacuum at room temperature for 3 hours to obtain silica particles whose particle surfaces were modified with long-chain alkyl groups. The obtained particles are designated as hydrophobic particles A.

Example 1
After 0.5 g of polystyrene was dissolved in 3 g of toluene, 0.05 g of amphiphilic particles A was added and sonication was performed for 1 hour to disperse the amphiphilic particles A in the solution. The obtained dispersion was added to 10 ml of pure water and subjected to ultrasonic treatment for 1 hour in an ice bath to form micellar particles, and then allowed to stand at room temperature for 12 hours. After standing, the solution was separated into an oil phase (upper layer) and an aqueous phase (lower layer) composed of polystyrene and toluene, and micelle particles were precipitated at the bottom. The oily phase was completely removed, and the remaining aqueous phase was heated to 333 K under normal pressure to evaporate water and toluene in the micellar particles, thereby recovering the micelle particles. By immersing the micellar particles in a 50% aqueous hydrofluoric acid solution, the amphiphilic particles A were dissolved to obtain spherical polystyrene particles formed in the internal space of the micellar particles. The obtained spherical polystyrene particles had a particle size of about 2 μm, and the particle sizes were almost uniform. Furthermore, when spherical polystyrene particles were observed with a scanning electron microscope (SEM), it was confirmed that the surface had a hemispherical concave structure. Electron micrographs of spherical polystyrene particles are shown in FIGS. 2 (a) and 2 (b).

Comparative Example 1
After dissolving 0.5 g of polystyrene in 3 g of toluene, 0.05 g of silica (Seahoster (KEP-30) manufactured by Nippon Shokubai Co., Ltd., average particle size 0.3 μm) is added, and sonication is performed for 1 hour. And silica was dispersed in the solution. When the obtained dispersion was added to 10 ml of pure water and subjected to ultrasonic treatment for 1 hour in an ice bath, the aqueous phase became cloudy, and when left as it was for 12 hours, a precipitate was formed at the bottom of the aqueous phase.

  When the resulting precipitate was collected and immersed in a 50% hydrofluoric acid aqueous solution to dissolve the silica and the residue obtained was observed with a scanning electron microscope (SEM), only amorphous polystyrene was observed. .

Comparative Example 2
After dissolving 0.5 g of polystyrene in 3 g of toluene, 0.05 g of hydrophobic particles A were added and sonication was performed for 1 hour to disperse the hydrophobic particles A in the solution. When the obtained dispersion was added to 10 ml of pure water and sonicated for 1 hour in an ice bath, the aqueous phase became cloudy. No precipitate was formed, and polystyrene particles could not be obtained.

  Furthermore, when left as it is for 12 hours, the white turbidity of the aqueous phase was drawn to the oil phase side consisting of polystyrene and toluene. This is presumably because the hydrophobic particles A are alkylsilylated over the entire surface, so that the alkylsilyl groups on the surface of the hydrophobic particles are attracted to the oil phase.

  The spherical polymer particle of the present invention has a very characteristic structure in which a surface is formed by a plurality of hemispherical concave surfaces, and supports a catalyst, a biosensor, a functional material carrier, a novel structural material. Application to various fields such as mold materials is expected.

In FIG. 1, (a) is a schematic diagram showing an embodiment of amphiphilic particles used in the present invention, and (b) is a schematic diagram of micellar particles formed by the amphiphilic particles. 2A and 2B are electron micrographs of the spherical polystyrene particles obtained in Example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Amphiphilic particle 2 Lipophilic group 3 Hydrophilic part 4 Lipophilic part 5 Water phase 6 Oil phase 7 Micellar particle

Claims (3)

  Spherical polymer particles having a surface formed by a plurality of hemispherical concave surfaces.   The spherical polymer particle according to claim 1, wherein the spherical polymer particle is made of polystyrene. (A) a step of dispersing amphiphilic particles capable of forming micellar particles in an organic solvent in which a polymer is dissolved;
(B) The step of mixing the dispersion obtained in step (a) with water to form micellar particles in which the polymer and organic solvent are taken into the interior by amphiphilic particles,
(C) removing the organic solvent contained in the micellar particles obtained in step (b) to solidify the polymer in the micelle particles, and (d) amphiphilic particles from the micelle particles. The manufacturing method of the spherical polymer particle of Claim 1 or 2 which has the process to remove.

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