KR20200020451A - Micro capsule, preparation method thereof, and micro sensor comprising the same - Google Patents

Abstract

The present invention provides a microcapsule having excellent reactivity and stability against external force, a manufacturing method thereof, and a microsensor of high performance including the same. For the above, the microcapsule surrounded by a polymer film includes: a photonic crystal area which includes a photonic crystal structure at least partially existing in the polymer film; and a non-photonic crystal area in the center of the microcapsule. Moreover, the present invention provides the microsensor including the microcapsule and the method of manufacturing the microcapsule. The present invention improves a reaction speed against external force since an additional phase separation does not occur in a photonic crystal area of the microcapsule by external force; has an effect of preventing the degradation of crystal stability of a photonic crystal structure forming a photonic crystal area; and thus, has an effect of manufacturing a microsensor of high performance when used as a microsensor.

Description

MICRO CAPSULE, PREPARATION METHOD THEREOF, AND MICRO SENSOR COMPRISING THE SAME

The present invention relates to a microcapsule comprising at least partly a photonic crystal region, a method of manufacturing the same, and a microsensor comprising the same.

Materials with regular refractive index changes at half the wavelength show an optical bandgap characteristic that does not allow light at that wavelength inside the material. Such materials are called photonic crystals. The optical bandgap is a similar principle that semiconductors do not allow electrons with an electron bandgap inside a material, so that a photonic crystal is also called a semiconductor of light. When light having a wide spectrum from the outside is incident on the photonic crystal, light corresponding to the optical band gap cannot be propagated inside, and thus reflection occurs selectively, and light of the remaining wavelengths propagates inside. Therefore, when the optical bandgap is present in the visible ray region, selective reflection by the optical bandgap is displayed in color.

Color development by photonic crystal is bright and shiny color and it is distinguished from general chemical color. Photonic crystals in nature include Morpho butterfly wings, peacock feathers, and miscalculations, all of which have a regular lattice structure of hundreds of nanometers inside, which is regular at half the wavelength of the color. The refractive index changes.

Thus, the color generated by the regular structure of the material, not the components that make up the material, is called the structural color. Unlike the general chemical color represented by the absorption of molecules, the structure color does not discolor or fade as long as the physical structure is maintained, and various colors can be expressed by the same material through the cycle control of the structure. Due to these features, structural color materials have recently been spotlighted in various areas, and are described as being particularly used as aesthetic coatings and colorless (non-toxic) colorants, security materials, display optical materials, and the like.

Photonic crystal spheres including such photonic crystals may be prepared by various methods, specifically colloidal crystallization by evaporation of a single droplet, colloidal crystallization using interparticle repulsive force, double droplet-based spherical photonic crystal encapsulation, and the like. have. The photonic crystal sphere manufactured as described above may be utilized as a sensor by varying the color expressed by various external forces. However, in the conventional photonic crystal sphere, since the photonic crystal is formed through electrostatic repulsive force or crystallization by entropy, the crystal region is formed uniformly inside the photonic crystal sphere. There is a problem in that additional phase separation is required, which is divided into many parts and no parts, thereby decreasing the reaction rate and degrading the stability of the crystal.

Specifically, Korean Patent Laid-Open Publication No. 10-2009-0109367 discloses a method and a use of a polymer capsule using double droplets having a photopolymerizable intermediate phase. Specifically, (a) an inner tube and an intermediate tube using a microtube. Manufacturing a microfluidic device consisting of a tube and an outer tube; (b) a water dispersion solution stream for the inner droplet containing the material to be confined in the inner tube of the microfluidic device, and a photopolymerizable monomer oil or colloidal dispersed photopolymerizable monomer oil stream including a surfactant in the middle tube; Introducing a stream of water containing a surfactant into the outer tube to form double droplets of uniform size; (c) discloses a method for producing a polymer capsule comprising the step of photocuring the double droplet through the ultraviolet exposure region downstream of the microfluidic device. However, the polymer capsule prepared by the above method does not disclose a configuration in which the color expressed by a change in external force is not disclosed, and even if such a configuration is included, a uniform photonic crystal region is formed in the polymer capsule. In addition, there is a problem in that the reaction speed to the change of the external force is slow, and there is also a problem in that the stability of the crystal is reduced by repeated external force changes.

Next, Korean Patent Laid-Open Publication No. 10-2016-0148816 discloses a temperature sensor including a liquid crystal capsule and a method for manufacturing the same, and specifically, a first phase and an oil flow including a water flow therein. An outer tube for containing two phases; An inner tube positioned on a first upper side of an inside of the outer tube; Preparing a microfluidic system including a; orifice located facing the inner tube, located in the second upper side of the inside of the outer tube (step 1); Forming a water flow comprising a first polymer in an outer tube of the microfluidic system prepared in step 1 and forming an oil flow flowing in a direction opposite to the water flow to form a first phase and a second phase (step 2); Preparing a double droplet in the orifice located in the second phase by forming a liquid crystal flow including the liquid crystal material in the same direction as the first phase in an inner tube located in the first phase formed in the step 2 (step 3 ); And hardening by irradiating ultraviolet rays to the double droplets prepared in step 3 (step 4); a liquid crystal capsule comprising a liquid crystal material surrounded by a film including the first polymer prepared through the step; And a matrix comprising a second polymer, wherein the temperature sensor is characterized in that the liquid crystal capsule is dispersed in the matrix. However, in the temperature sensor of the present invention, since the liquid crystal capsule is uniformly dispersed in the matrix, phase separation occurs in a portion in which a large amount of liquid crystal capsule exists in the matrix and a portion in which the liquid crystal capsule is almost absent at the time of temperature change. There is a problem in that the reaction rate is slow, and the stability of the photonic crystals formed by the liquid crystal capsules is lowered.

Accordingly, the inventors of the present invention have led to the present invention by studying a microcapsule that reacts quickly to external force changes such as temperature and does not degrade the stability of the photonic crystal even after repeated external force changes.

Republic of Korea Patent Publication No. 10-2009-0109367 Republic of Korea Patent Publication No. 10-2016-0148816

It is an object of the present invention to provide a microcapsule having excellent reactivity to external force and excellent stability, a method for preparing the same, and a high performance microsensor including the same.

To this end, the present invention is a microcapsule surrounded by a polymer film, the microcapsule comprising a photonic crystal region including a photonic crystal structure at least partially present in the polymer film; And a non-photonic crystal region in the center of the microcapsule, which provides a microcapsule comprising the microcapsule, and further comprises a microsensor including the microcapsule, and further, a method of manufacturing a microcapsule surrounded by a polymer film. Preparing nanoparticles whose size is changed by an external force; Supporting water including a plurality of the nanoparticles, a depletant, and an osmotic pressure control salt in a polymer membrane; And forming a photonic crystal region at least partially present in the polymer film from the plurality of nanoparticles, and forming a non-photonic crystal region in the center of the microcapsule. do.

According to the present invention, the external force does not cause additional phase separation of the photonic crystal region in the microcapsule, thereby improving the reaction speed with respect to the external force and preventing the crystal stability of the photonic crystal structure of the photonic crystal region from deteriorating. Therefore, when this is used as a micro sensor, there is an effect that can produce a high performance micro sensor.

1 is a schematic diagram of an exemplary microfluidic device for manufacturing the microcapsules of the present invention,
2 is a transmission optical micrograph of the microcapsules prepared in the embodiment of the present invention,
Figure 3 is an optical micrograph of the microcapsules prepared in the embodiment of the present invention,
4 is an optical micrograph showing the shape of the microcapsules according to the concentration of the raw material,
Figure 5 is a photograph showing the color development by temperature of the microcapsules prepared in the embodiment of the present invention,
6 is a graph showing the maximum peak position during heating and cooling of the reflection spectrum of the microcapsules prepared in the embodiment of the present invention,
7 is a graph showing the maximum peak position of the reflection spectrum during repeated heating and cooling for the microcapsules prepared in the embodiment of the present invention,
8 is a graph showing the rate of response to the temperature change of the microcapsules prepared in the embodiment of the present invention,
9 is a graph for measuring the reaction rate with respect to the temperature change of the microcapsules prepared in the embodiment of the present invention,
10 is a photograph showing the color development characteristics in the solvent of the microcapsules prepared in the embodiment of the present invention, and
11 is a photograph showing the applicability as a temperature sensor for a fluid using a microcapsules prepared in an embodiment of the present invention.

-Definition of Terms-

In the present invention, the 'dipant' is a material for forming a depletion force that is attractive between the nanoparticles forming the photonic crystal structure, and is generally smaller in size than the nanoparticles forming the photonic crystal structure, and surrounding the nanoparticles. It is distributed in

In the present invention, the 'external force' refers to any 'external stimulus' that changes the size of the nanoparticles forming the photonic crystal structure.

In the present invention, the 'average radius' refers to the arithmetic mean of the longest axis radius and the shortest radius in the nanoparticles or microcapsules of a specific shape.

In the present invention, "photonic crystal region" means a region where a photonic crystal structure exists, and "non-photonic crystal region" means a region where a photonic crystal structure does not exist.

Hereinafter, the present invention will be described in detail.

The present invention

A microcapsule surrounded by a polymer membrane,

The microcapsule includes a photonic crystal region including a photonic crystal structure at least partially present inside the polymer film; And

A non-photonic crystal region in the center of the microcapsule;

It provides a microcapsule comprising a.

Hereinafter, the present invention will be described in detail for each component.

The present invention relates to a microcapsule surrounded by a polymer film, the microcapsule comprising a photonic crystal region comprising a photonic crystal structure at least partially present inside the polymer film. The polymer membrane of the present invention defines the outer wall of the microcapsules and protects the photonic crystal structure inside the microcapsules from physical stimuli.

Conventional microcapsules including photonic crystal regions form photonic crystals by electrostatic repulsion or entropy crystallization in microcapsules. In this case, photonic crystal regions are formed over the entire microcapsule, and in response to external forces, In order to change the color, it is necessary to add an additional phase separation in which the colloidal photonic crystal is divided into many portions and no portions, and thus there is a problem in that the reaction rate and the stability of the crystal are degraded.

Accordingly, the microcapsules of the present invention form a photonic crystal region including a photonic crystal structure at least partially present in the polymer film, so that no additional phase separation occurs even when the photonic crystal region shrinks or relaxes due to an external force. The problem of lowering the reaction rate and the stability of the crystal was solved.

In this case, the photonic crystal region may be formed adjacent to the polymer film inside the polymer film.

Since the polymer film forming the microcapsules of the present invention may be cured through an additional step in the manufacturing process, it may be a photocurable polymer film or a thermosetting polymer film.

The microcapsules according to the invention comprise a non-photonic crystal region in the center thereof. Since the microcapsules of the present invention include a photonic crystal region at least partially present inside the polymer film and a non-photonic crystal region in the center, that is, a region in which the photonic crystal structure does not exist, phase separation is already performed at the time of completion of the microcapsule. When an external force is applied to the microcapsules, no additional phase separation occurs, and as a result, the reaction rate and crystal stability against the external force are improved.

The microcapsules according to the invention are preferably filled with a continuous fluid phase inside the polymer membrane. As the inside of the polymer film is filled with a continuous fluid phase, fluidity of the photonic crystal region with respect to the external force is obtained, and thus the external force can be detected by changing the emission color according to the change of the external force. That is, it is possible to perform a function as a sensor through the real-time control of the structure color of the external force.

In addition, the microcapsules according to the present invention may include a dipletant. The microcapsules of the present invention have a structure including a photonic crystal region including a photonic crystal structure at least partially present inside the polymer film and a nonphotonic crystal region in the center of the microcapsule. The microcapsules including the existing photonic crystal region are generally formed through crystallization by electrostatic repulsive force or entropy, thereby causing a problem of deterioration of reaction speed and stability of external crystals. The microcapsules according to the present invention include diplitants in the process of manufacture, thereby depleting force. Since the photonic crystal region and the non-photonic crystal region are separately formed in the microcapsule, color change can be realized quickly and stably with respect to the change of the external force.

The photonic crystal structure included in the photonic crystal region of the microcapsules according to the present invention may include a colloidal photonic crystal. According to the present invention, nanoparticles whose size is changed by an external force may be formed in a colloidal form, and colloidal photonic crystals may be formed in a microcapsule inside the microcapsule by using depletion force due to diffraction. Photonic crystal region.

Meanwhile, in the microcapsules according to the present invention, the average radius of the non-photonic crystal region may be 10 to 95% of the average radius of the microcapsules. If the average radius of the non-photonic crystal region is less than 10%, the photonic crystal region is formed in the microcapsule as a whole, thereby reducing the reaction speed and deteriorating the stability of the crystal as in the conventional microcapsule. If it exceeds 95%, there is a problem that too few photonic crystal regions are formed and color development is not sufficient.

The polymer membrane of the microcapsules of the present invention includes at least one member selected from the group consisting of polydimethylsiloxane (PDMS) prepolymer, trimethylolpropane ethoxylate triacrylate (ETPTA), and ethylene glycol phenyl ether acrylate (EGPEA). This may be a polymerized polymer membrane, but is not necessarily limited thereto, and may be thermally polymerized or photopolymerized, and may be used as the polymer membrane of the microcapsule of the present invention as long as it has a transparent characteristic after polymerization.

The photonic crystal structure of the microcapsules of the present invention may include nanoparticles whose size is changed by an external force. Hereinafter, a photonic crystal structure including nanocrystals whose size is changed by photonic crystal and external force will be described.

Materials with regular refractive index changes at half the wavelength show an optical bandgap characteristic that does not allow light at that wavelength inside the material. Such materials are called photonic crystals. The optical bandgap is a similar principle that semiconductors do not allow electrons with an electron bandgap inside a material, so that a photonic crystal is also called a semiconductor of light. When light having a wide spectrum from the outside is incident on the photonic crystal, light corresponding to the optical band gap cannot be propagated inside, and thus reflection occurs selectively, and light of the remaining wavelengths propagates inside. Therefore, when the optical bandgap is present in the visible ray region, selective reflection by the optical bandgap is displayed in color. Color development by photonic crystal is a shiny color and is distinguished from the color of general chemical dyes. Photonic crystals in nature include Morpho butterfly wings, peacock feathers, and opal gemstones, all of which have regular lattice structures on the order of hundreds of nanometers, which are regular at half the wavelength of the color. The refractive index changes. Thus, the color generated by the regular structure of the material, not the constituents of the material, is called structural colors. Unlike the general chemical color represented by the absorption of molecules, the structure color does not discolor or fade as long as its physical structure is maintained, and various colors can be expressed by the same material through the cycle control of the structure. Due to these characteristics, structural color materials have recently been spotlighted in various areas, and are expected to be used as aesthetic coatings and colorless dyes, security materials, and display optical materials.

In the present invention, since the microcapsules include nanoparticles whose size is changed by an external force, the structural cycle of the photonic crystal structure may be changed, and thus various colors may be developed.

In this case, the nanoparticles may be formed in a core-shell structure including a core part for implementing a structural color and a shell part whose size is changed by an external force. As such, when the nanoparticles are formed, the structure of the core portion is changed as the size of the shell portion is changed by external force, and thus, different structure colors may be colored in the core portion.

On the other hand, the external force to change the size of the nanoparticles may vary, specific examples may be temperature, pH, electric field, magnetic field, or osmotic pressure. The change of the external force changes the size of the nanoparticles, and thus the structure color of the photonic crystal structure is changed, and thus the external force in the region where the microcapsule is located can be visually confirmed through the changed color. .

Since the microcapsules according to the present invention have already been phase-separated into the photonic crystal region and the non-photonic crystal region at the time of manufacture, additional phase separation does not occur when the external force applied to the microcapsule changes, which can react quickly to the external force change. There is an advantage.

In addition, the present invention provides a micro sensor including the microcapsules as described above. In this case, the micro-sensor according to the present invention senses, for example, may be temperature, pH, magnetic field, or osmotic pressure, but is not necessarily limited thereto, and if the external force that can change the structural color of the photonic crystal structure of the photonic crystal region, The micro sensor of the present invention can detect such an external force.

Since the micro sensor according to the present invention can react quickly to changes in external force, there is an advantage in that the reaction speed is excellent. In addition, the micro-sensor according to the present invention can be uniformly distributed in the field in which the external force is present, and when distributed in this way, it can be visually confirmed that the external force locally changes in the field, and also dispersed in the fluid In this case, the flow distribution can be measured simultaneously with the fluid.

Furthermore, the present invention

As a method for producing a microcapsule surrounded by a polymer membrane,

Preparing nanoparticles whose size is changed by an external force;

Supporting water including a plurality of the nanoparticles, a depletant, and an osmotic pressure control salt in a polymer membrane; And

Forming a photonic crystal region at least partially present in the polymer film from the plurality of nanoparticles, and forming a non-photonic crystal region in the center of the microcapsule;

It provides a method for producing a microcapsule comprising a.

Hereinafter, the method of manufacturing the microcapsules of the present invention will be described in detail for each step.

The method for producing a microcapsule of the present invention includes the step of preparing a nanoparticle size is changed by the external force. In the present invention, the nanoparticles form a cluster on a colloid to form a photonic crystal region in a microcapsule of the present invention. Due to the characteristic of changing in size due to external force, the nanocapsule finally changes color. do.

In this case, the nanoparticles whose size is changed by an external force may be designed in various ways. For example, the core part may implement a structure color, and the shell part may be manufactured as a core-shell structure whose size is changed by an external force. In this case, as the shell portion is changed in size by an external force, the structure of the core portion is changed, and accordingly, different structural colors may be colored in the core portion.

As a specific example, when the core portion is formed of polystyrene having a structural color, and the shell portion is formed of a copolymer of poly-N-isopropylacrylamide and acrylic acid whose solubility in water varies depending on temperature, the nanoparticles are dispersed in water. In this state, the solubility of water in the shell portion changes according to the temperature change, thereby changing the nanoparticle size. When the photonic crystal region including the photonic crystal structure is formed of such nanoparticles, the lattice constant changes with temperature, and as a result, colorimetric characteristics that change color with temperature can be realized. .

Since the external force may be temperature, pH, electric field, magnetic field or osmotic pressure, and to produce nanoparticles that can vary in size in response to each external force, the following procedure may equally produce microcapsules, The manufacturing method has the advantage of producing a microcapsule that can react to various external forces in the same process.

The production method according to the present invention includes a step of supporting a water containing a plurality of the nanoparticles, depletant, and osmotic pressure control salt inside the polymer membrane. The polymer film performs the outer wall function of the microcapsules of the present invention, and the plurality of nanoparticles later form a photonic crystal region including a photonic crystal structure.

The diffntant forms a depletion force between the nanoparticles to form colloidal crystals at least partially within the polymer film in the form of a cluster, thereby forming a photonic crystal region including the photonic crystal structure.

The depletion force between the nanoparticles is proportional to the number density (density) of the discrete. In the step of supporting water containing a plurality of the nanoparticles, depletants, and osmotic pressure-controlling salt inside the polymer membrane in order to prevent the nanoparticles from being crystallized by depletion in advance before the microcapsules are formed, Use low concentrations of diffents. In order for the photonic crystal region to be formed thereafter, the number of diffraction numbers inside the film must be increased, and for this purpose, the osmotic pressure control salt is included. That is, after supporting the above water inside the membrane and increasing the salt concentration on the outside of the membrane, water inside the membrane is drawn out through the membrane due to the osmotic pressure difference. The photonic crystal region is thus formed.

On the other hand, the step of supporting the water containing a plurality of the nanoparticles, diplitants, and osmotic pressure control salt inside the polymer membrane can be carried out in a variety of ways, for example, oil phase and pre 2 The water phase is bounded by the outer tube, which is located inside the outer tube, the first water phase comprising the prepared nanoparticles, depletant, and osmotic pressure control flow, the first water phase The discharge end is located in the first inner tube located on the oil side of the outer tube, the inside of the outer tube, the end in which the manufactured microcapsules face the end of the first inner tube, the microcapsules Preparing a microfluidic system including a second inner tube whose end is introduced on the second water side of the outer tube; And allowing the first water phase to flow in the direction from the first inner tube to the second inner tube, thereby collecting the manufactured microcapsules into the second inner tube.

This step will be described in more detail with reference to FIG. 1.

The method is a method of forming a double emulsion using a microfluidic device, preparing a microfluidic system capable of forming a microcapsule, driving the microfluidic system to manufacture and collect the microcapsule.

In more detail, the microfluidic system is present when an oil phase including a prepolymer, which becomes a polymer membrane of a microcapsules by polymerization, and a second water phase, in which a microcapsule to be prepared is suspended in a colloidal phase. Located in the outer tube, the outer tube, the first water phase containing the prepared nanoparticles, dipliton, and osmotic pressure salt flows, the end of the first water phase is discharged and the oil phase of the outer tube Similarly to the first inner tube and the first inner tube positioned on the oil side with respect to the second water phase boundary, the end in which the manufactured microcapsule is introduced inside the outer tube and the end of the first inner tube is introduced And the end where the microcapsules are introduced is positioned on the side of the second water relative to the boundary between the oil phase and the second water phase of the outer tube. Claim to prepare a microfluidic system including a second inner tube.

When preparing the microfluidic system as described above and flowing the first water phase in the direction of the second inner tube from the first inner tube, the first fluid includes a plurality of the nanoparticles, diplitants, and salts for controlling osmotic pressure. As the water phase exits the end of the first inner tube, particles are formed in which the outer layer is formed by the oil phase, and the formed particles are collected by the second inner tube to disperse the formed particles in colloidal form in water.

In the manufacturing method of the present invention, after supporting the above water in the polymer film, a photonic crystal region at least partially present in the polymer film is formed from the plurality of nanoparticles, and a non-photonic crystal region in the center of the microcapsule is formed. Forming a step. That is, in this step, a photonic crystal region in which the photonic crystal is present and a non-photonic crystal region in which the photonic crystal region does not exist are formed in the microcapsules formed of the polymer film, wherein the photonic crystal region is adjacent to the polymer film in the polymer film. Can be formed. As described above, in the present invention, since the phase separation of the photonic crystal region and the non-photonic crystal region is already performed in the step of manufacturing the microcapsule, there is no need for additional phase separation at a later change in external force, so that the color change can be implemented quickly and stably.

Meanwhile, the forming of the photonic crystal region and the forming of the non-photonic crystal region in the center of the microcapsule as described above may be performed by various methods. For example, the inside of the microcapsule may be discharged to the outside by discharging water inside the microcapsule. It can be carried out by a method of increasing the number density of the number of. As the number of replicants increases, the depletion force acting on the nanoparticles also increases, leading to the crystallization of the nanoparticles. In addition, the depletion force is also affected by the shape of the object because it is proportional to the excluded volume, which decreases as the two objects approach. The decrease in volume of the dipliant that does not move when any nanoparticle is in contact with the membrane inner wall of the microcapsules is greater than the decrease in the volume of the decrease that cannot be moved when the two nanoparticles contact each other. Therefore, the depletion force between the membrane inner wall of the microcapsules and the nanoparticles is always greater than the depletion force between the two nanoparticles. As a result, the crystallization of the nanoparticles starts from the inner wall of the film so that a photonic crystal is formed adjacent to the capsule film, and a non-photonic crystal region is formed in the center of the microcapsule.

In the step of supporting the above water in the polymer membrane, the number density of the dipliant is not high enough so that the crystallization of the nanoparticles does not proceed, and in this step, the number of diplets in the capsule is discharged to the outside. Increasing the density (concentration) increases the depletion force, causing nanoparticles to crystallize.

In this case, the method of discharging the water inside the microcapsules may be performed in various ways, for example, the water inside the microcapsules may be discharged to the outside by using an osmotic pressure difference between the inside and the outside of the capsule.

The manufacturing method of the present invention may further comprise the step of curing the prepolymer film of the microcapsules prepared by the above method, wherein the curing may be carried out by a method of photocuring or thermosetting.

Prepolymers that can be used in the production process of the present invention are selected from the group consisting of polydimethylsiloxane (PDMS) prepolymer, trimethylolpropane ethoxylate triacrylate (ETPTA), and ethylene glycol phenyl ether acrylate (EGPEA) It may be a species or more, thermal polymerization or photopolymerization is possible, and if the polymer film is transparent after polymerization, it is not necessarily limited thereto.

Dipliants that can be used in the production method of the present invention may be at least one selected from the group consisting of polyacrylamide, N-isopropylacrylamide, and silica nanoparticles, but have a smaller size than nanoparticles forming photonic crystals, Dispersion in a solvent is easy, and if not having a property of adhesion with nanoparticles is not necessarily limited thereto.

In addition, the osmotic pressure control salt that can be used in the preparation method of the present invention may be at least one selected from the group consisting of NaCl salt, KCl salt, CaCl ₂ salt and MgCl ₂ , but if it has a high solubility in water It is not limited to this.

In the manufacturing method of the present invention, the second water phase may include a surfactant. The surfactant is selected from the group consisting of polyvinyl alcohol (PVA), glycerol, and poly (ethylene glycol) -block-poly (propylene glycol) -block-poly (ethylene glycol) (PEG-PPG-PEG, F108). One or more species may be used, so that the prepared microcapsules may be stably maintained.

In this case, the surfactant may be included in 3 to 30% by weight relative to the total second water phase, there is a problem that the prepared microcapsules may not be stably maintained in the water phase when the surfactant is included in less than 3% by weight, If it exceeds 30% by weight, it is difficult to control the density or osmotic pressure.

According to the manufacturing method of the present invention, it is possible to manufacture a microcapsule that can react sensitively to the change in external force, furthermore, only nanoparticles are designed differently according to the type of external force, and the rest of the process to produce a variety of microcapsules in the same way Since it is possible to do this, for example, there is an advantage of efficiently manufacturing various kinds of sensors.

Hereinafter, the present invention will be described in more detail with reference to Examples and Experimental Examples. However, the following Examples and Experimental Examples are only intended to explain the present invention, and the scope of the present invention is not intended to be limited and interpreted by the following description.

<Example>

Preparation of Microcapsules with Temperature Reactivity

(1) Preparation of Nanoparticles

Nanoparticles of uniform sized core-shell structure having a polystyrene core and a poly-N-isopropylacrylamide shell were synthesized by a two-step emulsion polymerization method. 155 mg of sodium lauryl sulfate (SLS, 99%, Sigma-Aldrich) and 1.875 g of N-isopropylacrylamide (NIPAm, 99%, Acros Organics) were dissolved in 135 mL of demineralized water. The resulting solution is poured into a 250 mL 4-neck round bottom flask equipped with a reflux condenser. The mixture was heated at 70 ° C. with a water bath in a nitrogen atmosphere while stirring at 50 rpm. The stirring speed was set at 300 rpm, and 38.36 mL of styrene (99%, Sigma-Aldrich) was introduced into the flask after the purification of the inhibitor on an aluminum oxide (99%, Junsei Chemical) column. After heating to 80 ° C., 90 mg of potassium persulfate (KPS, 99.99%, Sigma-Aldrich) was dissolved in 10 mL of demineralized water and introduced into the mixture. The mixture was reacted for 8 hours. The synthesized polystyrene particles were then purified with dialysate (Spectra / Po 4) with demineralized water for one week. To grow a shell of poly (N-isopropylacrylamide-co-acrylic acid) (p (NIPAm-co-AAc)), 478 mg of NIPAm, 3 mg of N, N'-methylenebis (acrylamide) ( 99%, Sigma-Aldrich), and 0.019 mL of acrylic acid (AAc, 99%, Sigma-Aldrich) were introduced into 20 mL of a dispersion of 3.86% by weight of diluted polystyrene particles in a 50 mL glass vial. The mixture was heated at 80 ° C. under rapid stirring at 300 rpm. To the mixture was added a solution made by dissolving 19 mg of KPS in 0.7 mL of demineralized water. The resultant reacted for 3 hours to prepare a core-shell structured nanoparticles. The above materials except styrene were used as received without purification. The prepared core-shell nanoparticles were observed by a field-emission scanning electron microscope (SEM) (Hitachi S-4800) and a dynamic light scattering apparatus (DLS, Malvern Nanosizer).

By the above method, the core part was formed in a uniform size in the range of 50 to 300 nm.

(2) Preparation of Microcapsules

A microcapsule was manufactured using the microfluidic device as shown in FIG. 1. On the first water, the prepared core-shell nanoparticles, poly (acrylamide-co-acrylic acid) (P (Am-co-AAc), Aldrich, Mw: 5,000,000) and sodium chloride (NaCl, Huxey, 99.5) %) Was included. The concentration of core-shell nanoparticles (C _colloid ), the concentration of _dipliant (C _dep ), and the concentration of sodium chloride (C _salt ) were 2.23 w / w%, 1.46 * 10 ⁻³ mol / m ³ , and 2.5, respectively. mol / m ³ . For each example the concentrations were varied as follows.

C _colloid
( w / w% ₎ 2.23 0.744 1.49 1.86 2.60 2.98 C _dep
( mol / m ³ ₎ 1.46 * 10 ^-3 1.82 * 10 ^-3 1.46 * 10 ^-3 0.909 * 10 ^-3 0.727 * 10 ^-3 0.364 * 10 ^-3 C _salt
( mol / m ³ ₎ 2.5 2.5 2.5 2.5 2.5 2.5

Polydimethylsiloxane (PDMS) prepolymer, crosslinking agent (Sylgard 184 kit, Dow Corning), and silicone oil (AR20, Sigma-Aldrich) in a weight ratio of 10: 1: 2.75 or photoinitiator 2-hydroxy-2 for the oil phase Ethoxylated trimethylolpropane triacrylate (ETPTA, Sigma-Aldrich, Mw = 428) containing 1 w / w% of methylpropiophenone (Darocur 1173, Sigma-Aldrich, 97%) was used.

After post-treatment of the microcapsules, in order to form a solid membrane of the microcapsules, it was thermosetted at 70 ° C. for 5 hours for the PDMS mixture and photocured with ultraviolet (UV) for the ETPTA mixture.

For the magnetic field reactivity of the membrane, Fe ₂ O ₃ nanoparticles (Sigma-Aldrich, Nanopowder, <50 nm) were dispersed in the oil phase at a concentration of 0.2 w / w%.

As the second water phase, an aqueous solution of polyvinyl alcohol (PVA, Sigma-Aldrich, Mw = 13,000 to 23,000) at a concentration of 10 w / w% was used. The first water phase, the oil phase, and the second water phase were all injected into the microfluidic device having the configuration of FIG. 1 at the same time using a syringe pump (Legato 100, KD Scientific), through which the microcapsules dispersed in the second water phase. Was prepared. The microcapsules produced were observed with a transmission microscope (Nikon Eclipse TS100) equipped with a high speed camera (Phantom Miro eX2, Vision Research).

(3) Formation of photonic crystal region and non-photonic crystal region

The prepared microcapsules were incubated in a solution of sodium chloride and PVA higher than the osmotic concentration inside the capsule to allow the water in the capsule to be discharged to the outside, thereby concentrating the nanoparticles, diplitants and salts. At this time, the salt concentration (C _{salt, out} ) of the solution of sodium chloride and PVA was 50 mol / m ³ . Experiments were performed with varying concentrations of 20, 50, 100 and 150 mol / m ⁻³ . Concentration generally took several days. In order to prevent the polymerization of PDMS on oil, the temperature was kept at 4 ° C. During the concentration, microcapsules were observed with an inverted optical microscope (Eclipse Ti-U, Nikon).

The microcapsules prepared by the above method were arranged as follows.

C _colloid
( w / w% ₎ C _dep
( mol / m ³ ₎ C _salt
( mol / m ³ ₎ Hardening C _{salt, out}
20mol / m ³ C _{salt, out}
50 mol / m ³ C _{salt, out}
100 mol / m ³ C _{salt, out}
150 mol / m ³ Example 1 2.23 1.46 * 10 ^-3 2.5 Heat cure O Example 2 0.744 1.82 * 10 ^-3 2.5 Heat cure O Example 3 1.49 1.46 * 10 ^-3 2.5 Heat cure O Example 4 1.86 0.909 * 10 ^-3 2.5 Heat cure O Example 5 2.60 0.727 * 10 ^-3 2.5 Heat cure O Example 6 2.98 0.364 * 10 ^-3 2.5 Heat cure O Example 7 2.23 1.46 * 10 ^-3 2.5 Heat cure O Example 8 0.744 1.82 * 10 ^-3 2.5 Heat cure O Example 9 1.49 1.46 * 10 ^-3 2.5 Heat cure O Example 10 1.86 0.909 * 10 ^-3 2.5 Heat cure O Example 11 2.60 0.727 * 10 ^-3 2.5 Heat cure O Example 12 2.98 0.364 * 10 ^-3 2.5 Heat cure O Example 13 2.23 1.46 * 10 ^-3 2.5 Heat cure O Example 14 0.744 1.82 * 10 ^-3 2.5 Heat cure O Example 15 1.49 1.46 * 10 ^-3 2.5 Heat cure O Example 16 1.86 0.909 * 10 ^-3 2.5 Heat cure O Example 17 2.60 0.727 * 10 ^-3 2.5 Heat cure O Example 18 2.98 0.364 * 10 ^-3 2.5 Heat cure O Example 19 2.23 1.46 * 10 ^-3 2.5 Heat cure O Example 20 0.744 1.82 * 10 ^-3 2.5 Heat cure O Example 21 1.49 1.46 * 10 ^-3 2.5 Heat cure O Example 22 1.86 0.909 * 10 ^-3 2.5 Heat cure O Example 23 2.60 0.727 * 10 ^-3 2.5 Heat cure O Example 24 2.98 0.364 * 10 ^-3 2.5 Heat cure O

C _colloid
(w / w%) C _dep
(mol / m ³ ) C _salt
(mol / m ³ ) Hardening C _{salt, out}
20mol / m ³ C _{salt, out}
50 mol / m ³ C _{salt, out}
100 mol / m ³ C _{salt, out}
150 mol / m ³ Example 25 2.23 1.46 * 10 ^-3 2.5 Photocuring O Example 26 0.744 1.82 * 10 ^-3 2.5 Photocuring O Example 27 1.49 1.46 * 10 ^-3 2.5 Photocuring O Example 28 1.86 0.909 * 10 ^-3 2.5 Photocuring O Example 29 2.60 0.727 * 10 ^-3 2.5 Photocuring O Example 30 2.98 0.364 * 10 ^-3 2.5 Photocuring O Example 31 2.23 1.46 * 10 ^-3 2.5 Photocuring O Example 32 0.744 1.82 * 10 ^-3 2.5 Photocuring O Example 33 1.49 1.46 * 10 ^-3 2.5 Photocuring O Example 34 1.86 0.909 * 10 ^-3 2.5 Photocuring O Example 35 2.60 0.727 * 10 ^-3 2.5 Photocuring O Example 36 2.98 0.364 * 10 ^-3 2.5 Photocuring O Example 37 2.23 1.46 * 10 ^-3 2.5 Photocuring O Example 38 0.744 1.82 * 10 ^-3 2.5 Photocuring O Example 39 1.49 1.46 * 10 ^-3 2.5 Photocuring O Example 40 1.86 0.909 * 10 ^-3 2.5 Photocuring O Example 41 2.60 0.727 * 10 ^-3 2.5 Photocuring O Example 42 2.98 0.364 * 10 ^-3 2.5 Photocuring O Example 43 2.23 1.46 * 10 ^-3 2.5 Photocuring O Example 44 0.744 1.82 * 10 ^-3 2.5 Photocuring O Example 45 1.49 1.46 * 10 ^-3 2.5 Photocuring O Example 46 1.86 0.909 * 10 ^-3 2.5 Photocuring O Example 47 2.60 0.727 * 10 ^-3 2.5 Photocuring O Example 48 2.98 0.364 * 10 ^-3 2.5 Photocuring O

Experimental Example 1

Optical Characterization of Microcapsules

(1) In order to confirm the appearance characteristics of the prepared microcapsules, the following experiment was performed. The microcapsules prepared in Examples 9 and 19 were observed by transmission optical microscope, and the results are shown in FIG. 2. According to Figure 2, it can be seen that the size of the prepared microcapsules is very uniform, showing a uniform color. In FIG. 2 the scale bar is 200 μm.

(2) The following experiment was conducted to confirm the structure of the prepared microcapsules. The microcapsules prepared in Example 1 were observed under an optical microscope, and the results are shown in FIG. 3. According to FIG. 3, it can be seen that the photonic crystal region is formed along the inner surface of the polymer film of the microcapsule, and the nonphotonic crystal region is formed at the center of the capsule. In FIG. 3 the scale bar is 100 μm.

(3) In order to observe the prepared microcapsules by raw material concentration, the following experiment was performed. Five microcapsules prepared in Examples 20 to 24 were confirmed with an optical microscope, and the results are shown in FIG. 4. Referring to FIG. 4, it can be seen that as the concentration of the colloid increases, photonic crystal regions are formed in more regions of the inner surface of the polymer film of the capsule. In FIG. 4 the scale bar is 100 μm.

Experimental Example 2

Temperature Reactivity Analysis of Microcapsules

(1) In order to confirm the temperature reactivity of the microcapsules according to the present invention, the following experiment was performed. The microcapsules prepared in Example 7 were observed under an optical microscope under different temperature conditions, and the results are shown in FIG. 5. The scale bar of FIG. 5 is 200 μm. According to FIG. 5, it can be seen that the color of the microcapsule of the present invention actually changes remarkably with temperature, and furthermore, the color changes but the brightness of the color does not change.

(2) The following experiment was carried out to check whether the microcapsules according to the present invention had a constant color upon heating and cooling. The microcapsules prepared in Example 7 were obtained by using a fiber-coupled spectrometer (USB 4000, Ocean Optics) at each temperature while discontinuously heating and cooling the temperature from 25 ° C. to 40 ° C. A graph with the maximum peak positions at each temperature is shown in FIG. 6. According to Figure 6, it can be seen that the position of the maximum peak at each temperature at the time of heating and cooling is almost the same, accordingly, the microcapsules of the present invention have a constant color development at a constant temperature during heating and cooling, It can be seen that hysteresis is not shown in the process of heating and cooling.

(3) When the heating and cooling were repeated for the microcapsules according to the present invention, the following experiment was carried out to check whether the color development was kept constant. While repeatedly heating and cooling the microcapsules prepared in Example 7 at 25 ° C. and 35 ° C., reflection spectra were obtained in the same manner as described above, and graphs were shown with the maximum peak positions for each cycle. . According to Figure 7, it can be seen that the microcapsules according to the present invention maintains the same color at a constant temperature even if the cycle increases.

(4) When heating or cooling the microcapsules according to the present invention, the following experiment was carried out to determine how quickly they react to temperature changes. The microcapsules prepared in Example 7 were heated at a rate of 0.5 ° C./s from 25 ° C. to 35 ° C., and after a certain time, the microcapsules were cooled again from 35 ° C. to 25 ° C. at the same heating rate, and the reflection spectrum was obtained in the same manner as above. 8 and a graph with maximum peak positions for each time. According to FIG. 8, it can be seen that the microcapsules according to the invention upon heating and cooling react very rapidly and change color.

(5) In order to confirm the reaction time for the temperature change of the microcapsules according to the present invention, the following experiment was performed. The microcapsules prepared in Example 7 were heated at a rate of 0.5 ° C./s from 25 ° C. to 35 ° C., and the heating portion of FIG. 8, which is the maximum peak position for each time measured, was enlarged. heating). In addition, the maximum peak position at equilibrium at each temperature obtained in FIG. 6 is shown as an in equilibrium in FIG. 9. In addition, the temperature change with time during the heating process is indicated by a solid line corresponding to the right axis. According to Figure 9, it can be seen that the maximum response time (Max. Delay) to the temperature change of the microcapsules of the present invention is discolored at a very fast rate of 6.4 seconds.

(6) In order to confirm the discoloration characteristics in the solvent of the microcapsules according to the present invention, the following experiment was performed. The plurality of microcapsules prepared in Example 7 were dispersed in a water solvent and vigorously stirred while maintaining at 25 ° C., 28 ° C., 31 ° C., and 35 ° C., and their color development states were shown in FIG. 10. According to FIG. 10, it can be seen that the microcapsules according to the present invention exhibit stable discoloration characteristics despite the shear stress caused by the strong flow of the dispersion solvent.

Experimental Example 3

Application review as microsensor

In order to confirm whether the microcapsules according to the present invention can be applied as a microsensor for checking the fluid temperature, the following experiment was performed. The microcapsules prepared in Example 7 were dispersed in a water solvent contained in a cuboid container, the solvent was heated by a heating stage (T95-PE, Linkam Scientific) on the lower left side of the vessel, and a cooling pipe on the right side. Cooling the solvent confirmed the color development of the microcapsules dispersed in the solvent, the results are shown in FIG. Figure 11 (a) is a photograph of the microcapsules color development in the actual solvent, Figure 11 (b) is a two-dimensional mapping of the hue and speed of the microcapsules. Hue was measured on a 55 × 17 pixel grid, represented by a rectangle in the figure, and the hues of one to five microcapsules located within each grid were measured using an image analysis program (ImageJ) to correspond to the average Hue value. The grid is represented by color. The velocity of the microcapsules was measured on a 10 × 7 grid and the velocity was determined by measuring the change in position of the microcapsule located in the center of each grid over time. The speed is indicated by a white arrow, with the head of each arrow representing the direction of the speed, and the length representing the magnitude of the speed for two seconds of travel. In each figure the scale bar is 5 mm. (C) of FIG. 11 shows the relationship between a pause value and a temperature. According to the figure, it can be seen that the microcapsules of the present invention accurately visualize the temperature distribution and the gradient in the solvent through different colors. In addition, the location of each capsule may be measured over time to simultaneously measure the flow of fluid. Therefore, it can be seen that the microcapsules of the present invention are suitable for use as a microsensor for checking the temperature distribution and the movement of the fluid.

Claims (18)

A microcapsule surrounded by a polymer membrane,
The microcapsule includes a photonic crystal region including a photonic crystal structure at least partially present inside the polymer film; And
A non-photonic crystal region in the center of the microcapsule;
Microcapsule comprising a.
The method of claim 1,
The microcapsule is characterized in that the inside of the polymer membrane is filled with a continuous fluid phase.
The method of claim 1,
And the microcapsule comprises a discrete.
The method of claim 1,
The photonic crystal structure is a microcapsule comprising a colloidal photonic crystal.
The method of claim 1,
And the average radius of the non-photonic crystal region is 10 to 95% of the average radius of the microcapsule.
The method of claim 1,
The photonic crystal structure is a microcapsule, characterized in that it comprises nanoparticles whose size is changed by an external force.
The method of claim 6,
The nanoparticle is a micro-capsule, characterized in that the core-shell structure comprising a core portion for implementing the structure color, and the shell portion is changed in size by an external force.
The method of claim 6,
The external force is a microcapsule, characterized in that one kind selected from the group consisting of temperature, pH, electric field, magnetic field, and osmotic pressure.
Micro sensor comprising a microcapsule according to claim 1.
The micro sensor of claim 9, wherein the sensor senses one selected from the group consisting of temperature, pH, electric field, magnetic field, and osmotic pressure.
As a method for producing a microcapsule surrounded by a polymer membrane,
Preparing nanoparticles whose size is changed by an external force;
Supporting water including a plurality of the nanoparticles, a depletant, and an osmotic pressure control salt in a polymer membrane; And
Forming a photonic crystal region at least partially present in the polymer film from the plurality of nanoparticles, and forming a non-photonic crystal region in the center of the microcapsule;
Method for producing a microcapsule comprising a.
The method of claim 11,
The nanoparticles are the core portion of the structure to implement the color, the shell portion manufacturing method of the microcapsule, characterized in that the core-shell structure is changed in size by the external force.
The method of claim 12,
The external force is a method for producing a microcapsule, characterized in that one selected from the group consisting of temperature, pH, electric field, magnetic field, and osmotic pressure.
The method of claim 11,
The step of supporting water containing a plurality of the nanoparticles, depletant, and osmotic pressure control salt inside the polymer membrane
An outer tube in which an oil phase comprising a prepolymer and a second water phase exist at a boundary,
Located inside the outer tube, the first water phase containing the prepared nanoparticles, depletant, and osmotic pressure control flows, the end of the first water phase is discharged to the oil phase side of the outer tube A first inner tube located at
A second end positioned inside the outer tube and having an end to which the manufactured microcapsules are introduced faces an end of the first inner tube, and a second end to which the microcapsules are introduced is located on the second water side of the outer tube. Inner tube
Preparing a microfluidic system comprising a; And
Allowing the first water phase to flow in a direction from the first inner tube to the second inner tube to collect the manufactured microcapsules into a second inner tube;
Method for producing a microcapsule, characterized in that carried out including a.
The method of claim 11,
The forming of the photonic crystal region and the forming of the non-photonic crystal region in the center of the polymer film may be performed by discharging water inside the microcapsule to the outside to increase the number density of the diffractive number inside the microcapsule. Method for producing a microcapsule, characterized in that.
The method of claim 11,
The method of manufacturing a microcapsule further comprises the step of curing the polymer film of the microcapsules.
The method of claim 14,
The second water phase is a manufacturing method of a microcapsule, characterized in that it comprises a surfactant.
The method of claim 17,
The surfactant is a method for producing a microcapsule, characterized in that contained in 3 to 30% by weight based on the second water phase.

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