KR101365754B1 - Preparation of metal decorated hybrid microspheres with controlled surface nanostructures - Google Patents

Abstract

The present invention relates to a method for producing a metal nanoparticle-block co-polymer hybrid microparticle, comprising the steps of: 1) preparing an emulsion droplet of a block copolymer having two or more unit blocks; 2) evaporating the solvent of the emulsion droplets to produce block copolymer colloidal particles; And 3) adjusting the size and structure of the particles by adding a metal precursor selectively having an affinity for any of the unit blocks to the colloidal particles to allow the metal precursor to interact with a particular unit block. Provided are methods for preparing decorative hybrid microparticles.

Description

Manufacturing method of metal-decorated hybrid microparticles with controlled surface nanostructures {PREPARATION OF METAL DECORATED HYBRID MICROSPHERES WITH CONTROLLED SURFACE NANOSTRUCTURES}

The present invention relates to a method for producing hybrid microparticles decorated with nano-sized surface structures.

Metal nanoparticle hybrid block copolymer microparticles can have a high active surface area and unique optical properties and thus can be applied to a variety of catalysts, sensors and optical applications.

Among the microparticles having a nanostructured surface, in particular, there are known methods for producing raspberry-type particles in which small hemispheres containing metal nanoparticles are regularly arranged on the surface of the microparticles. It was attached to the microparticles using chemical interactions between the particles and organic molecules on the microparticle surface (Agrawal, M .; Rubio-Retama, J .; Zafeiropoulos, NE; Gaponik, N .; Gupta, S .; Cimrova, V .; Lesnyak, V .; Lopez-Cabarcos, E .; Tzavalas, S .; Rojas-Reyna, R .; et al. Langmuir , 24, 9820; and Ming, W .; Wu, D; van Benthem, R de With, G. Nano Lett. 5, 2298). For example, amino-functionalized ligands on microparticles (Guan, N ,; Xu, J .; Wang, L .; Sun, D. Colloids Surf., A , 346, 221; and Isenbugel, Kl Gehrke, Y. Ritter, H. Macromol. Rapid Commun. , 33, 41) were used to attach iron or silica nanoparticles, and thiol-functionalized ligands (Love, JC; Estroff, LA; Kriebel, JK; Nuzzo, RG; Whitesides). , GM Chem Rev , 105 , 1103) have been used to interact with gold, silver or copper nanoparticles. However, this method requires certain types of nanoparticles and organic molecules on microparticles, thus limiting the type of raspberry structured particles that can be produced.

Recently, a method for producing raspberry particles using a self-assembled structure of a block copolymer micelle having a crosslinkable core unit has been reported (Cheng, F .; Zhang, KK; Zhu, L .; Jiang, M .; Chen , DY Macromolecules , 42 , 7108; Huang, R .; Jiang, M .; Chen, DY J Mater Chem , 20 , 9988).

Although several methods have been proposed as described above, there is still a need for a method for more easily and efficiently manufacturing hybrid microparticles decorated with metal nanoparticles.

 Agrawal, M .; Rubio-Retama, J .; Zafeiropoulos, N. E .; Gaponik, N .; Gupta, S .; Cimrova, V .; Lesnyak, V .; Lopez-Cabarcos, E .; Tzavalas, S .; Rojas-Reyna, R .; et al. Langmuir, 24, 9820.  Ming, W .; Wu, D; van Benthem, R .; de With, G. Nano Lett. 5, 2298.  Guan, N ,; Xu, J .; Wang, L .; Sun, D. Colloids Surf., A, 346, 221.  Isenbugel, K.l Gehrke, Y .; Ritter, H. Macromol. Rapid Commun., 33, 41.  Love, J. C .; Estroff, L. A .; Kriebel, J. K .; Nuzzo, R. G .; Whitesides, G. M. Chem Rev, 105, 1103.  Cheng, F .; Zhang, K. K .; Zhu, L .; Jiang, M .; Chen, D. Y. Macromolecules, 42, 7108; Huang, R .; Jiang, M .; Chen, D. Y. J Mater Chem, 20, 9988.

Accordingly, the present invention seeks to provide a method for producing metal-decorated hybrid microparticles having a controlled surface in a simpler way.

In order to achieve the above object,

1) preparing an emulsion droplet of block copolymer having two or more unit blocks;

2) evaporating the solvent of the emulsion droplets to produce block copolymer colloidal particles; And

3) adjusting the size and structure of the particles by adding a metal precursor selectively having an affinity for any of the unit blocks to the colloidal particles to allow the metal precursor to interact with a particular unit block It provides a method for producing hybrid microparticles.

According to a preferred embodiment of the present invention, the emulsion droplets may be prepared by dissolving the block copolymer in an organic solvent and then adding an aqueous surfactant solution.

In addition, according to a preferred embodiment of the present invention, the organic solvent selectively has affinity for any one of the unit blocks of the block copolymer.

According to a preferred embodiment of the present invention, since the unit block having affinity with the metal precursor and the unit block having affinity with the organic solvent are different from each other, the surface structure of the particles can be controlled by using the affinity between the metal precursor and the specific unit block. have.

According to a preferred embodiment of the present invention, the surface of the fine particles may have a dot pattern in which the hemispherical protrusions of the metal material are regularly arranged.

In addition, according to another embodiment of the present invention, the surface of the microparticles may have a fingerprint pattern in which the hemispherical protrusion of the metal material is linearly fused.

According to a preferred embodiment of the present invention, the block copolymer comprises poly (vinylpyridine) and forms a micelle having poly (vinylpyridine) as a core, and the metal is a metal capable of interacting with poly (vinylpyridine). Can be.

Preferably, the metal may be gold, platinum or iron oxide.

According to a preferred embodiment of the present invention, the nano-pattern made of metal may be selectively located only in the poly (vinylpyridine) domain located on the surface of the microparticles.

In another aspect, the present invention provides a metal-decorated hybrid microparticles, which are prepared by the above-described method, characterized in that the nano-pattern made of metal is selectively positioned only in one domain of the unit block located on the surface of the microparticles.

According to the present invention, metal hybrid microparticles having a controlled surface can be easily produced by inserting a precursor having a selective affinity for any one block of the block copolymer, and the resulting hybrid microparticles Because of its high active surface area and unique optical properties, it can be used in a variety of applications including catalysts, optical sensors, surface-enhanced Raman spectroscopy, metamaterials and plasmonics.

1 is a schematic view for explaining a metal-block copolymer hybrid microparticle formation process according to the present invention.
2 is an optical image (scale bar 10 μm) and SEM image (scale bar 200 nm) of PS-b-P4VP colloidal particles.
3 is a surface and cross-sectional TEM image of PS-b-P4VP colloidal particles (scale bar 100 nm).
4 is an AFM image of PS-b-P4VP micelle (scale bar 250 nm).
FIG. 5 is a TEM image and UV-visible absorption spectroscopy graph of PS-b-P4VP microparticles decorated with gold nanoparticles (scale bar 20 nm).
Figure 6 is the EDX spectrum of PS-b-P4VP microparticles decorated with gold nanoparticles, the inset is a TEM image of the cross section (scale bar 80nm).
7 is an SEM image of PS-b-P4VP microparticles decorated with gold nanoparticles according to the microparticle diameter (scale bar 200 nm).
8 is a graph showing the distance between the hemisphere diameter of the swelling surface and the adjacent hemisphere as a function of the microparticle diameter.
9 is a (a) FLIM image of PS-b-P4VP microparticles decorated with gold nanoparticles (diameter 810 nm) and (b) fluorescence lifetime measurement graph (average lifetime 3.3 ± 0.2 ns).
10 is a schematic view showing the evolution of the surface structure according to the degree of swelling of the fine particles of various diameters.
11 is a TEM image of P4VP colloidal particles (scale bar 50 nm).
12 is a SEM, TEM photograph and EDX image of PS-b-P4VP microparticles decorated with various metals (scale bar 100 nm).

The present invention provides a method for producing metal-decorated hybrid microparticles having controlled surfaces in a simpler way.

First, the block copolymer microparticles are prepared by an emulsion method. These microparticles can be inserted into the metal precursor by direct reduction, so that the nanoparticles are located only near the surface of the microparticles. Because the P4VP domain near the surface is selectively swollen with the metal precursor, a unique dot pattern or fingerprint pattern is formed on the surface of the microparticle during the metal precursor insertion process, depending on the diameter of the microparticle.

The maximum absorption wavelength of the gold-decorated microparticles was observed at about 580 nm, which means that the gold nanoparticles are aggregated or densely packed in the P4VP domain near the microparticle surface. In addition, as the size of the microparticles increases, their fluorescence lifetime is much longer than that of the small microparticles. In addition, it is possible to produce a variety of hybrid microparticles, including iron nanoparticles and platinum nanoparticles as well as gold nanoparticle decorative microparticles. Therefore, the hybrid microparticles prepared by the present invention can be applied to a variety of catalysts, sensors and optical applications due to the high active surface area and unique optical properties.

Hereinafter, a gold decorative hybrid microparticles will be described as a preferred embodiment of the present invention.

Gold-decorated microparticles with various surface morphologies can be prepared by infiltration of the gold precursor into polystyrene-b-poly (4-vinylpyridine) (PS-b-P4VP) microparticles. The microparticles can be prepared by emulsifying the PS-b-P4VP polymer in chloroform in an aqueous surfactant solution and then evaporating chloroform. Selective swelling of P4VP domains in the microparticles with gold precursors under acidic conditions can result in the formation of gold decorative microparticles with various surface nanostructures.

According to a preferred embodiment of the present invention, when the fine particles are larger than 800 nm, the surface pattern of the fingerprint shape is smaller than 800 nm, and the dot surface pattern is formed. In addition, the gold nanoparticles are located in the P4VP domain near the surface of the microparticles to be produced.

The method of the present invention for preparing gold nanoparticle hydride block copolymer microparticles can also be applied to other nanoparticle systems, such as iron oxide or platinum nanoparticles, and can be used efficiently to form hybrid microparticles with controlled surface structures. have.

Block copolymer colloidal particles can be prepared by evaporating the organic solvent in the emulsion droplets using emulsion droplets in the aqueous block copolymer solution. The nanostructure of these particles is unique and can be controlled by varying the volume fraction of the blocks, the particle size and the interfacial tension at each block and droplet interface.

For example, onion-type particles can be prepared using symmetric diblock copolymers, while other nanostructured particles can be prepared simply by adding low molecular weight homopolymers in various proportions.

It is also known that the nanomorphology inside the block copolymer is significantly affected by block interaction with the droplet surface (ie, the regulating surface), and the overall colloidal particle shape changes during structural evolution as the solvent evaporates.

Colloidal composite particles having complex internal nanophases can be prepared by injecting functional nanoparticles into the block copolymer particles using existing methods used in thin film production.

Injecting inorganic nanoparticles into polymer nanostructures is largely divided into ex-situ and in-situ methods. The ex-situ method utilizes cooperative self-organization of preformed nanoparticles and block copolymers. Injecting and controlling the position of the nanoparticles in the block copolymer blend controls the surface properties of the nanoparticles by end-bonding ligands such as organic molecules, homopolymers, mixtures of homopolymers or copolymers to the surface of the nanoparticles. In addition, various nanoparticles can be injected by controlling their position in the polymer matrix as long as they are coated with a suitable ligand.

In-situ synthesis of nanoparticles in block copolymer templates utilizes preformed micelles of block copolymers comprising metal precursors. This method requires that one of the blocks has a strong affinity for the metal precursor. Such blocks include poly (2-vinylpyridine) (P2VP) and poly (4-vinylpyridine) (P4VP) in which nitrogen atoms interact strongly with metal precursors. The metal-polymer composite particles can be prepared by directly reducing the metal precursor inside the block copolymer micelle using, for example, a reducing agent or a plasma treatment. However, no method of in-situ forming the metal particles in the submicron block copolymer particles formed in the emulsion template process as in the present invention has been reported.

The present invention provides a simpler and more convenient method for preparing metal-block copolymer hybrid microparticles having controlled surface nanostructures. First, microparticles or spherical aggregates of polystyrene-b-poly (4-vinylpyridine) (PS-b-P4VP) polymer micelles are prepared by emulsion encapsulation and shrinkage methods. Gold precursors in acidic water are then added so that metal nanoparticles form only near the surface of the microparticles. Unexpectedly, a unique dot or fingerprint pattern occurs during the metallization process as the P4VP domain selectively swells and migrates to the surface (see FIG. 1). As a result, it is possible to successfully prepare gold nanoparticle composite microparticles and to control the surface morphology.

Hereinafter, a preferred embodiment of the present invention will be described in more detail, but the scope of the present invention is not limited to the following examples.

≪ Example 1 >

Preparation of Fine Particles Using PS-b-P4VP Polymer

The characteristics of PS-b-P4VP (Polymer Sources Inc.) used in the experiment are as follows.

Total molecular weight (Mn) = 262 kg / mol (PS Mn = 198 kg / mol, P4VP Mn = 64 kg / mol)

Polydispersity (PDI) = 1.14

A 1% by weight solution of PS-b-P4VP in chloroform was added 4.5 mL of distilled water containing 1% by weight of surfactant (Pluronic F108 (PEO-b-PPO-b-PEO, 14,600 g / mol, Sigma Aldrich)) The mixture was emulsified by treating with an ultrasonic mill for 10 minutes. Distilled water was added and diluted with the obtained aqueous emulsion, and the organic solvent was evaporated using rotary evaporator at 50 degreeC under reduced pressure. The result was annealed at 95 ° C. for 24 hours to form an internal structure. The dispersion was washed with deionized water, followed by centrifugation (13,000 rpm, 30 minutes) to remove the remaining surfactant.

Insertion of metal nanoparticles into block copolymer micelle microparticles

To prepare fine particles decorated with gold nanoparticles, a gold precursor (HAuCl ₄ · 3H ₂ O, Aldrich) solution was added to the microparticle dispersion in a 1: 1 molar ratio based on P4VP units. After the mixture was stirred for 24 hours, the mixture was washed with deionized water and centrifuged (13,000 rpm, 30 minutes). The result was redispersed in deionized water to evaluate its properties.

Characteristic measurement method

Field emission scanning electron microscope (FE-SEM, Hitachi S-4800) and transmission electron microscope (TEM, JEOL 2000FX) were used to observe the surface and internal structure of metal decorative microparticles. Samples were prepared by drop-casting microparticle suspensions on silicon wafers, washing and sputtering with gold in order to visualize the surface structure of the microparticles using FE-SEM. In order to observe the surface structure of the microparticles using the TEM, a sample was prepared by dipping a TEM grid coated with a 20-30 nm thick carbon film in a fine particle suspension and drying in air. Prepared samples were exposed to iodide vapor to selectively stain the P4VP domain of PS-b-P4VP. However, after inserting the gold precursor into the PS-b-P4VP microparticles, the samples were analyzed without staining due to the strong contrast between the gold nanoparticles and the polymer domain. The size and distribution of PS-b-P4VP micelles and gold nanoparticles in suspension were analyzed by FE-SEM, TEM and AFM images. Cross-sectional TEM photographs were used to investigate the internal structure of the microparticles, and samples were prepared by drop casting the microparticle suspension onto an epoxy film and then drying the solvent. The epoxy support film was cured in a 60 ° C. oven for 24 hours and then cut into 50 nm slices using a diamond knife.

UV-visible absorption spectra (Cary 50 Conc UV-Vis spectroscopy) and fluorescence lifetime imaging (FLIM, Hitachi F-7000) were performed to evaluate the optical properties of microparticles decorated with gold nanoparticles. Fluorescence lifetime imaging (FLIM) was performed using an inverted type confocal scanning microscope (Micro Time-200, Picoquant, Germany) (100X objective). A single-mode pulsed diode laser (470 nm output, half width full-to-96 ps instrument response function, 40 MHz repetition rate, average output less than 1 Hz) was used as excitation source.

From gold nanoparticle decorative samples spin-coated on glass coverslips, using dichroic mirrors (490 DCXR, AHF), long-pass filters (HQ500lp, AHF), 50 μm pinholes and single-photon avalanche diodes (SPAD) The emitted light (λ> 500 nm) of was collected. Data collection was based on time-correlated single photon counting (TCS-PC). Time resolved fluorescence decay curves were obtained from FLIM images, and fluorescence lifetimes were obtained from nonlinear least squares repetition curves (SymPhoTime software version 5.1.3).

The presence of metals (gold, Fe _x O _y , and platinum, etc.) in the hybrid metal-block copolymer microparticles was confirmed by energy dispersive X-ray spectroscopy (EDX, JEOL). Samples were prepared through the same process as the TEM samples except that they were not dyed.

Measurement result

To the block copolymer colloidal particles, a chloroform solution containing 1% by weight of PS-b-P4Vp diblock copolymer was added to water containing 1% by weight of a surfactant (Pluronic F108), followed by emulsion using a high intensity ultrasonic irradiator. It was made. Chloroform was then slowly evaporated to produce block copolymer colloidal particles. 2 is an optical image of PS-b-P4VP colloidal particles. The particles were well dispersed in water (see Figure 2 (a)). From the SEM image (FIG. 2C), it can be seen that the spherical colloidal particles have a smooth surface. On the other hand, after treating the colloid particles with an aqueous solution of gold precursor (HAuCl ₄ ), it has a rough surface covered with hemispherical shape (see FIG. 2 (d)). The surface structure is regular in size and arrangement. In addition, colloidal particles into which gold nanoparticles are inserted are also well dispersed in water (see FIG. 2 (b)).

3 is a surface and cross-sectional TEM image of PS-b-P4VP colloidal particles. The surface and cross-sectional TEM images of the particles were observed to closely observe the morphological changes at the surface of the block copolymer colloidal particles. For cross-sectional imaging, the particles were dropped on an epoxy film and then dried. The sample was carefully cut at room temperature to obtain a 50 nm thick film. As can be seen in Figures 3 (a) and (c), the spherical micelle structure of the PS-b-P4VP polymer with the P4VP core was observed. The P4VP core is a dark-looking area in the colloidal particles because it is selectively dyed with iodine vapor.

Asymmetric PS-b-P4VP polymers with high molecular weight (Mn = 262 kg / mol, PDI = 1.14, f _ps = 0.76) have a much higher affinity for chloroform for PS than P4VP, so PS corona and P4VP cores in chloroform solutions Spherical micelles were formed. The polymer-solvent interaction coefficient ( X ) between PS chain and chloroform is known as 0.34, which is much smaller than the coefficient (1.55) between P4VP chain and chloroform. The average P4VP core size of PS-b-P4VP micelles in the colloidal particles is estimated to be 47.5 ± 9.2 nm from the TEM image. This value corresponds to the P4VP core mean size (43.7 ± 3.1 nm) obtained by AFM measurement. AFM measurements were made of monolayer samples of PS-b-P4VP micelles on Si substrates with 0.5% by weight of PS-b-P4VP chloroform solution. AFM measurements (see FIG. 4) also show that the average size of PS-b-P4VP micelles obtained from the center-to-center distance between two different P4VP micelle cores is 59.5 ± 5.8 nm.

After injecting the gold precursor into the microparticles, the microparticle surface was significantly converted into a dot-shaped pattern on the smooth surface. 3 (b) and (d) show the surface and cross-sectional TEM images of the microparticles decorated with gold nanoparticles observed without iodine staining. According to FIG. 3 (b), small hemispheres containing gold nanoparticles are regularly arranged on the surface of the microparticles to have a structure resembling a raspberry. This structure corresponds to the SEM image of Fig. 2 (d). Cross-sectional TEM images of the microparticles were taken to investigate the internal structure of the gold decorative microparticles. The TEM image of FIG. 3 (d) shows that the gold precursor was inserted only in the P4VP domain near the surface, not in the internal P4VP domain of the microparticles. Since the P4VP domain is isolated by the PS matrix in the microparticle particles, the gold precursor cannot reach the P4VP domain inside the microparticle. In FIG. 3 (d), the P4VP domain appears slightly darker than the PS matrix because electron scattering from the poly (vinylpyridine) polymer is stronger than the PS polymer.

Unlike the conventional method, the method of the present invention provides a raspberry-type particle having a dot shape on the surface based on swelling and deswelling by selectively inserting gold nanoparticles into the P4VP domain together with acidic water. Can be.

5 is a TEM image and UV-visible absorption spectroscopy graph of PS-b-P4VP microparticles decorated with gold nanoparticles. In order to evaluate the properties of the gold nanoparticles of the P4VP domain located on the surface of the microparticles, TEM and UV-Vis spectroscopy were performed (see FIG. 5). The diameter distribution of gold nanoparticles was used for the cross-sectional TEM image, and the insertion figure of FIG. In addition, the average diameter of the gold nanoparticles was maintained regardless of the size of the microparticles. FIG. 5 (b) compares the UV-visible absorption spectra for microparticles before (solid line) and after (dashed line) with gold precursor solution to further confirm gold nanoparticle formation. For the microparticles obtained after the gold nanoparticles were inserted, the maximum absorption peak was observed at about 580 nm, which is a signal that gold nanoparticles are present. It is well known that the absorption spectrum of gold nanoparticles is very sensitive to the nanoparticle diameter, but the peak position (~ 580 nm) of gold nanoparticle decorative microparticles is the typical absorption peak of gold nanoparticles (size 2-5 nm). 520 nm) compared to the red shift. On the other hand, when the gold nanoparticles are close enough to each other, the absorption peak may shift to a higher wavelength because the dipole plasmon mode of the gold nanoparticles may be combined. For example, the UV-visible absorption peak of a gold cluster of gold nanoparticles of 2 nm or less is observed at a higher position than the wavelength of the individual gold nanoparticles. Therefore, the redshift UV-visible absorption peak indicates that gold nanoparticles are densely packed in the P4VP domain near the surface of the microparticles (see FIG. 5 (b)). In addition, the presence of gold nanoparticles in the outermost layer of the microparticles was also confirmed in the energy dispersive X-ray spectrum (EDX) measurement results (see FIG. 6).

Morphological conversion due to the addition of gold nanoparticles was observed according to the change of microparticle diameter. 7 is an SEM image of PS-b-P4VP microparticles (250-1190 nm in diameter) decorated with gold nanoparticles. As can be seen in FIGS. 7 (a)-(d), distinctly distinct and regular dot patterns can be observed on small particles ((a) 250 nm, (b) 360 nm, (c) 540 nm (d) 640 nm, (e) 1020 nm and (f) 1190 nm). If the microparticle diameter is 800 nm or less, the arrangement of the hemispherical protrusions is regular, that is, a raspberry type structure. However, as the microparticle diameter increases, the surface morphology is transferred, changing from the distinctive dot structure to the continuous fingerprint structure. When the microparticle diameter exceeded 800 nm, the hemispherical protrusions showed a fingerprint pattern in which linear fusions may have been made (see FIGS. 7 (e) and (f)).

In order to more closely observe the surface structure of gold-decorated microparticles, SEM images were taken to show the diameter of the swelling micelles and the distance between adjacent surface structures on the microparticles as a function of the microparticle particle diameter (see FIG. 8). 8 shows that the size of the gold-nanoparticle intercalated P4VP hemisphere on the microparticle surface increases from 40 nm with increasing microparticle diameter. However, when the diameter of the fine particles reached 800 nm, the hemisphere diameter became saturated to about 50 nm. The micelles on the surface of the microparticles are combined in various ways depending on the curvature of the microparticles. Small microparticles with a large curvature surface have a small P4VP hemisphere diameter because the number of micelles on the surface is small and therefore unlikely to merge. The smaller the curvature, the more micelles merge at the surface, resulting in an increase in the diameter of the P4VP hemisphere. However, since the distance between the hemispheres depends on the PS brush length on the P4VP hemisphere, the distance was found to be constant at about 16 nm regardless of the microparticle diameter.

The fluorescence properties of gold nanoparticle decorative microparticles are important for understanding the structural behavior of the gold nanoparticles in the P4VP domain and the morphological transition of the microparticle surface. Fluorescence lifetimes depend mainly on the size of the gold nanoparticles, the particle periphery interactions and the fluorophore concentration. Therefore, fluorescence lifetime imaging was performed on gold nanoparticle decorative microparticles having various microparticle diameters and surface structures, and the results are shown in FIG. 9. The lifetime values for various microparticle sizes are summarized in Table 1.

As the diameter of the microparticles increased, the fluorescence lifetime increased, because the gold nanoparticles showed 1.7 nm regardless of the diameter of the microparticles, and the increase in the fluorescence life was not due to the change in the size of the individual gold nanoparticles. In contrast, it is well known that fluorophore concentrations have an effect on lifetime, although intrinsic lifetime does not change, minor resorption occurs because higher fluorophore concentrations increase resorption potential in areas of high bulk solution. Throughout the process, life is usually increased. Therefore, the present inventors believe that the fluorescence lifetime increases as the diameter of the fine particles increases because a larger number of gold nanoparticles can participate in the reabsorption process in the microparticles. For example, as the microparticle diameter increases from 380 nm to 810 nm, the surface P4VP hemispheres increase from 40 nm to 50 nm, resulting in an increase in the number of gold nanoparticles per P4VP domain, resulting in a fluorescence lifetime of 2.1 ± 0.2 to 3.3 ± 0.2. increased to ns. In addition, the fluorescence lifetime was further increased to 3.7 ns as the particle diameter increased from 810 nm to 1380 nm. The inventors believe that this phenomenon is due to the change in surface structure from dot shape to fingerprint, resulting in more gold nanoparticles per P4VP domain on the surface.

The inventors studied the morphological changes in the swelling and sea swelling process. Since the surface of the spheres is wrinkled to minimize energy, various patterns are formed by the surface wrinkles on the core cell spheres. As the film stress in the particles increases, the protrusions merge together to evolve into a maze pattern to save stretching energy. The shape observed in the present invention is very similar to the wrinkled sphere. The results of the present invention also show that microparticles with various surface structures were formed as a function of particle diameter and surface curvature.

10 is a schematic diagram showing the evolution of the surface structure according to the degree of swelling of the fine particles of various diameters. As shown in Fig. 10 (a), before the addition of the gold precursor, PS-b-P4VP spherical micelles are present in the microparticles, the PS blocks are significantly swollen by a solvent (chloroform) and P4VP collapsing in contrast. It is. Thus, the spherical shape is maintained in the microparticles. When the microparticles are treated with acidic water, they swell into the P4VP domain near the surface and burst through the surface coating of the PS brush to form a mushroom of high swell P4VP. If the surface curvature is high enough, the P4VP mushrooms do not contact each other and have a dot shape. However, as the surface curvature decreases, the swollen mushrooms come into contact with each other to form a continuous semicylindrical shape.

<Comparative Example>

P4VP colloidal particles were prepared in the same manner as in Example 1, except that P4VP polymer was used instead of PS-b-P4VP polymer.

FIG. 11 is a TEM image of P4VP colloidal particles, showing before (a) and after (b) the gold precursor insertion. Unlike the PS-b-P4VP precursors, P4VP colloidal particles did not show morphological changes with the addition of gold nanoparticles. In addition, gold nanoparticles were uniformly formed throughout the P4VP colloidal particles. Therefore, it can be seen that the presence of PS-b-P4VP spherical micelles is an important factor for the production of gold nanoparticle decorative microparticles having a controlled surface structure.

<Example 2 and Example 3>

Since P4VP polymers can interact with various metal precursors, the method of the present invention can be used to produce hybrid microparticles containing various types of metal nanoparticles. To prepare microparticles using different kinds of metal nanoparticles, chloroplatinic acid hexahydrate (HPt ₂ Cl ₆ · 6H ₂ O) and iron (III) chloride (FeCl ₃ ) were used as metal precursors (purchased from Aldrich). . Except for the kind of metal precursor, platinum nanoparticles and iron oxide (Fe _x O _y ) nanoparticles were decorated using the same method as in Example 1, hybrid microparticles.

12 are SEM (top left), TEM (top right) and EDX (bottom) images of PS-b-P4VP microparticles decorated with iron oxide (a) and platinum (b) nanoparticles. SEM, TEM and EDX images of PS-b-P4VP microparticles adorned with various metals. As a result of observing the microparticle morphology, similar to the gold nanoparticle hybrid microparticle system, the addition of the metal precursors FeCl ₃ and HPt ₂ Cl ₆ · 6H ₂ O, respectively, dramatically changed the surface of the microparticle from a smooth surface to a dot pattern surface. It was. Formation of iron oxide and gold nanoparticles on the P4VP domain of the microparticles was observed by TEM image. EDX results also confirm the presence of iron oxide and gold nanoparticles in the microparticles.

Claims (9)

Preparing an emulsion droplet of polystyrene-polyvinylpyridine double block copolymer;
Evaporating the solvent of the emulsion droplets to produce colloidal particles comprising spherical micelles comprising a polyvinylpyridine core and a polystyrene corona; And
A metal precursor having an affinity for polyvinylpyridine is added to the colloidal particles to form a metal decoration of a dot pattern in which hemispherical protrusions are regularly arranged on the surface of the colloidal particle, or a metal decoration of a fingerprint pattern in which the hemispherical protrusions are linearly fused to the surface. Comprising;
Method for producing metal-decorated hybrid fine particles containing metal decoration on the surface
The method of claim 1,
The polystyrene-polyvinylpyridine double block copolymer is a polystyrene-poly-2-vinylpyridine double block copolymer or a polystyrene-poly-4-vinylpyridine double block copolymer.
The method of claim 1,
The emulsion droplets are prepared by dissolving the polystyrene-polyvinylpyridine double block copolymer in an organic solvent and then adding an aqueous surfactant solution to prepare the metal-decorated hybrid fine particles.
The method of claim 3, wherein
The organic solvent is a method for producing metal-decorated hybrid fine particles, characterized in that the polystyrene-polyvinylpyridine double block copolymer having affinity for polystyrene.
The method of claim 3, wherein
The organic solvent is a method for producing metal-decorated hybrid fine particles, characterized in that chloroform.
The method of claim 1,
The metal of the metal precursor is a method for producing metal-decorated hybrid fine particles, characterized in that any one of gold, platinum, or iron.
Metal-decorated hybrid fine particles produced by the method according to any one of claims 1 to 6. delete delete

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