JP6651310B2 - Nanoparticle and method for producing the same - Google Patents

Description

  The present invention relates to a surface-modified nanoparticle and a method for producing the same.

  In recent years, quantum dots (QDs), which are attracting attention as phosphors, have been put to practical use as electronic devices and fluorescent labels for living bodies, and vigorous research is still ongoing.

  Quantum dots are rarely used alone, and are often used in combination with other materials, such as dispersion in resin. At this time, it was necessary to modify the surface of the quantum dots accordingly in order to improve the dispersibility in other materials. Patent Document 1 describes polymer-modified metal sulfide nanoparticles that can be easily dispersed in a solution or a resin.

JP 2006-76831 A

  However, the conventional quantum dots have a problem that they cannot be appropriately dispersed in a fluorocarbon solvent (including a resin solution). Further, Patent Document 1 does not disclose a surface modification treatment for improving dispersibility in a CFC-based solvent.

  The present invention has been made in view of the above points, and in particular, has an object to provide a nanoparticle having a surface modifier optimized and having good dispersibility in a CFC-based solvent, and a method for producing the same. .

Nanoparticles in the present invention, the surface of the nanoparticles, fluorobenzenethiol, fluoroalkane alcohol, perfluorocarboxylic acid, fluoroalkanethiol, fluoroalkaneamine, and, among the fluoroalkane ester, A surface modifier that has been surface-modified with two or more different surface modifiers and has decanethiol as an alkanethiol constituting a fluoroalkanethiol system, and an undecylamine as an alkaneamine constituting a fluoroalkaneamine system And a surface modifier having the following .

  It is possible to improve the dispersibility of the nanoparticles that have been surface-modified with the surface modifier described above in a CFC-based solvent.

  In the present invention, the nanoparticles are preferably CdSe quantum dots. The quantum dot in the present invention can be suitably used as a sealing material for LEDs and the like.

  In the present invention, the nanoparticles are preferably fluorescent nanoparticles. ADVANTAGE OF THE INVENTION According to this invention, while the dispersibility of a nanoparticle in a fluorocarbon-based solvent can be made favorable, the fluorescence intensity of a nanoparticle can be improved and it can be used suitably as a fluorescent nanoparticle.

The method for producing nanoparticles according to the present invention comprises the steps of: producing nanoparticles; and treating the nanoparticles with a fluorobenzenethiol system, a fluoroalkane alcohol system, a perfluorocarboxylic acid system, a fluoroalkanethiol system, a fluoroalkaneamine system and alkanes of the fluoroalkane ester, by addition of two or more different surface modifiers, have a, a step of surface modification treatment of the surface of said nanoparticles to form a fluoroalkane thiol It is characterized in that a surface modifier having decanethiol as a thiol and a surface modifier having undecylamine as an alkaneamine constituting a fluoroalkaneamine are used in combination . By the surface modification treatment in the present invention, nanoparticles excellent in dispersibility in a fluorocarbon solvent can be appropriately and easily produced.
In the present invention, it is preferable to add the surface modifier having decanethiol first, and then add the surface modifier having undecylamine.

  ADVANTAGE OF THE INVENTION According to this invention, the dispersibility of the surface-modified nanoparticle in the CFC-based solvent can be improved. Further, in the present invention, the fluorescence intensity of the nanoparticles can be increased.

3 is a flowchart showing steps of a method for screening nanoparticles according to an embodiment of the present invention. It is a graph which shows the relationship between the wavelength of the evaluation sample in Experiment-3, and absorbance. It is a graph which shows the relationship between the wavelength and the intensity of the evaluation sample in Experiment-3.

  Hereinafter, an embodiment of the present invention (hereinafter, abbreviated as “embodiment”) will be described in detail. The present invention is not limited to the following embodiments, but can be implemented with various modifications within the scope of the gist.

  Nanoparticles in the present embodiment, the surface of the nanoparticles, fluorobenzene thiol-based, fluoroalkane alcohol-based, perfluorocarboxylic acid-based, fluoroalkanethiol-based, fluoroalkaneamine-based, and fluoroalkaneester-based Among them, the surface is modified by at least one kind of surface modifying agent. Here, the “system” is a concept including isomers, denatured products, and the like.

  In the above surface modifier, the alkane alcohol constituting the fluoroalkane alcohol is octanol, the carboxylic acid constituting the perfluorocarboxylic acid is octanoic acid, and the alkanethiol constituting the fluoroalkanethiol is Is decanethiol, the alkaneamine constituting the fluoroalkaneamine is preferably octylamine, and the alkaneester constituting the fluoroalkaneester is preferably octyl propionate.

  As shown in the experiments described below, it is known from the experimental results described below that the surface-modified nanoparticles can have good dispersibility in a chlorofluorocarbon-based solvent and can increase the fluorescence intensity of the nanoparticles. .

  In addition, as the surface modifier, pentadecafluorooctylamine or tridecafluorooctyl propionate can be selected, so that the surface modification treatment conditions other than the surface modifier type can be selected widely, and it is appropriate and easy. Further, the dispersibility in a CFC-based solvent can be enhanced, which is preferable.

  The surface modification treatment conditions in the production of nanoparticles in the present embodiment can be determined based on the following nanoparticle screening method. The screening method can be added to a series of processes in the nanoparticle manufacturing process. That is, the method for producing nanoparticles in the present embodiment includes, in addition to the production of nanoparticles-surface modification treatment, screening-determination of surface modification treatment conditions-generation of nanoparticles-surface modification treatment. Can also. Hereinafter, a method for screening nanoparticles will be described.

  The nanoparticle screening method according to the present embodiment includes a step of subdividing the nanoparticle turbid liquid into a storage portion of a storage container, a step of performing a surface modification treatment on each nanoparticle turbid liquid under different conditions, The method includes a step of obtaining an evaluation sample by dispersing the evaluation sample in a dispersion medium, and a step of evaluating the evaluation sample by an absorption spectrum or a fluorescence spectrum.

  For example, in the present embodiment, it is possible to generate a large number of evaluation samples with different surface modification conditions using a microwell plate having a large number of holes (wells), and perform a series of optical analysis evaluations of these evaluation samples. And

  FIG. 1 is a flowchart illustrating steps of a method for screening nanoparticles according to an embodiment of the present invention.

  In step ST1 shown in FIG. 1, a turbid liquid containing nanoparticles (hereinafter, referred to as a QD liquid) containing quantum dots is generated. Quantum dots can be synthesized by mixing a compound that is a raw material of a constituent element to generate a precursor solution, and reacting the precursor solution using, for example, a microreactor. The synthesized quantum dots can be subjected to a purification process by a known method. The QD liquid can be obtained by mixing the purified quantum dots with a solvent. The solvent is not limited, and examples thereof include alcohols, ketones, toluene, and water.

  Next, in step ST2 shown in FIG. 1, the QD liquid obtained in step ST1 is injected little by little into a large number of storage sections provided in the storage container. As the storage container, for example, a microwell plate in which wells as storage units are arranged in a matrix can be used. As described above, in the present embodiment, screening can be performed using an existing microwell plate. Alternatively, a plate-shaped container in which a number of individual containers from which a well portion can be removed can be used. The material of the container is not limited, but glass is preferably used. In particular, it is preferable that the container is made of a material having better heat resistance and chemical resistance than plastics by the incubation step. In addition, it is desirable that the container be covered with a cap or film to prevent evaporation of the solvent during the incubation and optical analysis. In particular, by using a cover coated with Teflon (registered trademark) as the cover during the optical analysis, it is possible to prevent the solvent from eroding the cover, causing the cover to be whitened, thereby lowering the analysis accuracy. In addition, by making the storage container a material having excellent thermal conductivity, it is possible to apply substantially even heating to each of the QD liquids subdivided into the respective storage sections. Therefore, variations in the heating temperature can be suppressed, and highly accurate evaluation can be performed for each evaluation sample.

  Although the number of storage sections arranged in the storage container is not limited, specifically, it is preferably 50 or more, more preferably 96 or more, and further preferably 150 or more. In addition, the volume of each storage unit is, for example, 3.0 mL or less, preferably 1.5 mL or less. Furthermore, since the viscosity of the monomer serving as a dispersion medium is generally high, stirring is difficult when the sample amount is too small. For this reason, it is desirable that the volume of the storage section is 0.5 mL or more, preferably 1.0 mL or more. In the experiments described later, a microwell plate having 96 glass wells provided in a plate holder made of plastic or aluminum is used.

  The QD concentration to be injected into each container can be calculated from the QD concentration actually desired in the matrix and the amount added to each container. Specifically, the QD concentration is preferably at least 0.1%, more preferably at least 1%, further preferably at least 10%. The volume of the QD solution is several tens μL or less (specifically, 50 μL or less), preferably 20 μL or less, more preferably 10 μL or less, and even more preferably 5 μL or less. In the present embodiment, the QD liquid used in one storage container is adjusted by setting the amount of the QD liquid to be added to each of a plurality of, preferably 50 or more storage units to tens of μL or less, preferably 20 μL or less. As a whole, the amount can be suppressed to several mL or less, and the amount of the reagent per condition can be about 1/10 to 1/100 of the conventional amount. Therefore, it is particularly effective in searching for surface treatment conditions of a developed product whose quality is not stable. Further, since many quantum dots and surface modifiers are expensive, the amount of reagent used per experiment using a container can be reduced, which is effective in terms of cost.

  Subsequently, in the present embodiment, a surface modification process is performed in step ST3 of FIG. At this time, different types of surface modifiers are added to each QD liquid. For example, in Experiment 1 described below, eight types of surface modifiers (surfactants) are used.

  In the present embodiment, the surface modification conditions can be made different depending on the following factors. For example, (1) the type of modifier, (2) the concentration of the surface modifier, (3) the solvent concentration during the surface modification treatment, and (4) the incubation time.

  As shown in FIG. 1, in the surface modification treatment, a surface modifier and a solvent are added under different conditions (step ST3-1), and subsequently, incubation is performed (step ST3-2).

  The addition of the surface modifier can be performed in two or more steps as in Experiment-2 and Experiment-3 described below. Further, the solvent of the surface modifier may not be used (that is, the surface modifier is directly added to the QD liquid). Further, as the solvent, it is preferable to use a solvent in which the quantum dots are dispersed and the surface modifier is dissolved, such as toluene.

  By this step ST3, the surface modification treatment can be performed on the QD liquid stored in each storage section under different conditions.

  The incubation can be performed using an oven or an incubator. In the incubation, the temperature and the time are adjusted. In the present embodiment, the incubation can be performed at once under the same conditions for all the QD solutions stored in the respective storage units. In addition, at the time of incubation, it is desirable to stir the solution using a shaker, a magnetic stirrer, or a fine stirring rod in order to avoid segregation of the surface modifier due to QD aggregation.

  Furthermore, it is desirable to apply ultrasonic dispersion, since the coagulation state can be alleviated in a shorter time and the uniformity of the solution in the well is improved. Furthermore, if necessary, different incubation temperature conditions can be applied by, for example, incubating a sample prepared under the same conditions on a hot plate subjected to a temperature gradient.

  After the addition of the surface modifier and the solvent, the above-described shaking treatment, stirring, ultrasonic treatment and the like may be performed before the incubation. In this case, heating the sample to 40 to 100 ° C. lowers the viscosity of the medium, and facilitates stirring and the like. Vacuum degassing before, during, or after incubation as needed to remove low boiling impurities such as moisture and volatile contaminants, and the dispersion medium (such as toluene) used in the nanoparticle suspension It is also possible. Also in this case, it is easier to remove the solvent by heating as necessary.

  Next, in step ST4 shown in FIG. 1, a flocculant is added after the incubation. The flocculant is not particularly limited as long as it has a polarity different from the surface polarity of the quantum dots. For example, when quantum dots and a surface modifier are dispersed in a chlorofluorocarbon-based solvent, toluene becomes an aggregating agent. Alternatively, an alcohol such as ethanol can be a flocculant.

  Next, in step ST5 shown in FIG. 1, the quantum dots are filtered or settled to remove the supernatant. Thereby, surface-modified quantum dots can be obtained. For example, after repeatedly adding the flocculant and centrifuging, the process may move to step ST5. At this time, the coagulants used in the repetition step may be the same type or different types. In addition, whether to perform step ST4 and step ST5 can be arbitrarily determined.

  Next, in step ST6 shown in FIG. 1, the surface-modified quantum dots accommodated in each accommodation unit and the dispersion medium are mixed to generate an evaluation sample. For mixing, for example, a shaker for a microplate can be used. In the present embodiment, the mixing can be performed on each evaluation sample at the same time. As described above, in this embodiment, many evaluation samples having different surface modification conditions can be generated at once.

  Next, in step ST7 shown in FIG. 1, an optical analysis evaluation is performed on each evaluation sample. The evaluation can be mainly performed by an absorption spectrophotometry and a fluorescence analysis. This makes it possible to evaluate the dispersibility and fluorescent properties of the quantum dots. In addition, if an absorption spectrum or a fluorescence spectrum can be taken as an absorptiometry or a fluorescence analysis method, a change in the shape of the absorption spectrum or the fluorescence spectrum causes the degree and speed of dissolution, the cause of the fluorescence inactivation (dissolution or In addition, it is more preferable because information such as dissolution of additives, interaction with QDs, and their rates can be known at the same time.

  The evaluation can be performed by focusing on the absorbance obtained by the fluorescence method. In other words, when the quantum dots are highly aggregated, light scattering is increased, and the transmittance is reduced. Therefore, for example, when an absorption spectrum is measured, the baseline increases. Furthermore, in the case of measuring the absorption spectrum, the absorption peak position is related to the particle size, and when the peak disappears, it means that the quantum dot has dissolved or phase-separated and disappeared from the optical path.

  On the other hand, when an LED is used as a light source, the condition is that the absorbance inherent in the sample itself (the sum of the absorbance of the QD itself + the absorbance of the target dispersion medium) does not increase by 0.1 or more from the absorbance at a wavelength of 0.1 or less. In addition, the dispersibility can be evaluated. On the condition that the absorbance at the excitation wavelength does not significantly decrease (specifically, does not decrease by 10% or more), it can be evaluated that there is no disappearance of QD and no phase separation. The evaluation of the baseline and the disappearance of the peak can be evaluated by comparing with a reference evaluation sample (reference sample). For example, the reference sample may be a quantum dot dispersed in a good solvent such as toluene before the surface modification treatment.

  When there are many wavelengths at which the above-described sample itself has an absorbance of 0.1 or less, a wavelength as short as possible is desirable because the scattering intensity is high. In particular, it can be evaluated on condition that the absorbance in visible light having a wavelength of 720 nm or less is 0.1 or less.

  Further, in the fluorescence intensity obtained by the fluorescence photometry, when the fluorescence intensity is lower than, similar to, or higher than the fluorescence intensity of the above-mentioned reference sample, or when compared with the reference sample. Can be evaluated by the decrease rate and the increase rate of the fluorescence intensity.

  In optical analysis at the time of evaluation, high-speed measurement is possible, so that individual evaluation samples can be quickly evaluated, and the time required for characteristic evaluation of a large number of evaluation samples stored in a container has been reduced. It can be shortened compared to.

  Further, in the present embodiment, the above-described evaluation can be performed using a plurality of light emitting diodes arranged to face the plurality of storage units as a light source. In this embodiment, the measurement can be performed while moving each sample between one light receiving device and the light emitting diode. The above-described evaluation can be performed by using the above-mentioned evaluation unit. As described above, it is more preferable to perform the above-described optical analysis evaluation in a state where the light-emitting diode and the light receiving unit are opposed to each other with a predetermined distance therebetween so as to sandwich the container of the present embodiment from above and below. As a result, the optical analysis evaluation can be performed on a large number of evaluation samples at once, and the time required for searching for surface modification conditions can be more effectively shortened than in the past.

  In addition, a monochromatic light emitting diode may be used as the light emitting diode, or a two-color LED (a multi-color LED if necessary) and an optical filter are used together as long as the spectrum of light emitted from the light emitting diode does not overlap. Can be. At this time, it is also possible to reduce the space and the amount of reagent by using a structure in which only light having a wavelength necessary for dispersibility evaluation or dissolution and fluorescence intensity evaluation is detected by the light receiving unit.

  Furthermore, by performing the optical analysis continuously over a long period of time, a temporal change in the absorbance or the fluorescence intensity can be captured, so that the temporal stability of the sample itself can be confirmed.

  Further, as the light source for optical analysis used in the present embodiment, a white light source such as a xenon lamp can also be used. However, as described above, a plurality of light emitting diodes arranged to face the plurality of housing portions It is preferable to carry out the evaluation by using as a light source. The wavelength of the light emitting diode in the case of the absorbance evaluation is a wavelength at which the absorbance of the nanoparticles and the medium in which the nanoparticles are dispersed is 0.1 or less (for example, in the case of QD that emits visible light, , And 700 nm for the red light-emitting particles). Furthermore, when it is desired to investigate the dissolution of the particles or the separation of the solvent, it is desirable to use light-absorbing and fluorescent nanoparticles at the same wavelength as the excitation light source for fluorescence described later.

  In the case of fluorescence evaluation, the wavelength must be such that the nanoparticles are efficiently and appropriately excited (for example, 350 nm, 365 nm, 375 nm, 385 nm, 395 nm, 400 nm, 405 nm, 410 nm, 420 nm, 430 nm, 440 nm, 450 nm, and 460 nm). Is desirable. The light-emitting diode for evaluating the absorbance and the light-emitting diode for evaluating the fluorescence may be used in combination, or may be appropriately replaced when used. In this embodiment, the fluorescence and the spectrum of the transmitted light can be obtained and analyzed using a diffraction grating or the like. However, as described above, the spectrum is arranged so as to face the plurality of storage units. The evaluation is preferably performed using the plurality of light receiving elements as the light receiving unit. In the case of fluorescence evaluation, it is desirable to insert an optical filter for shielding the light emitting element between the light emitting element and the light receiving element in order to block incident light from the light emitting element. As a result, the evaluation can be performed on a large number of evaluation samples at once, and the time required for searching for the surface modification conditions can be effectively reduced as compared with the related art.

  As described above, according to the present embodiment, the nanoparticle suspension is subdivided into a plurality of storage units, and the surface modification treatment is performed on the nanoparticles in each storage unit under various experimental conditions, and the conditions are different. A plurality of evaluation samples of a combination can be created, and it is possible to perform a series of optical analysis evaluations on these evaluation samples. Therefore, in the present embodiment, it is possible to use a large number of evaluation samples at a time to study surface modification conditions and the like. Further, the predetermined treatment in the surface modification treatment can be collectively and evenly performed on a large number of evaluation samples divided into storage containers. As described above, in the present embodiment, it is possible to reduce the time required for searching for surface modification conditions, reduce the amount of samples and reagents, and to more easily manage conditions and evaluations, and to reduce labor compared with the related art. Can be reduced.

  In the present embodiment, the above-described method for screening nanoparticles can be presented as a screening system. That is, in the screening system according to the present embodiment, the nanoparticle suspension is subdivided into each of the plurality of storage units provided in the storage container, and the surface modification treatment of the nanoparticles is performed under different conditions for each of the storage units. The dispersion medium is added to each of the storage units, an evaluation sample in which the nanoparticles and the dispersion medium are mixed is generated, and the evaluation sample of each of the storage units is evaluated by optical analysis. It is characterized by.

  Subsequently, the following experiment was specifically attempted using the nanoparticle screening method shown in FIG.

[Experiment on Surface Modifier for Dispersion in Fluorocarbon Solvent-1]
The surface modification conditions of the CdSe-based quantum dots used for the encapsulating material for the LED were examined with the dispersibility in hexafluorometa-xylene in mind.

  First, in Step ST1 of FIG. 1, a nanoparticle turbid liquid (QD liquid) containing CdSe quantum dots was generated.

  For example, each compound as a raw material of the Cd source and the Se source was dissolved to generate a CdSe-based precursor solution. Then, the CdSe-based precursor solution was reacted using a microreactor to synthesize CdSe-based quantum dots.

  Subsequently, the shells of ZnS and ZnSe were coated on the surface of the CdSe quantum dots. For example, a first shell portion made of ZnSe synthesized by reacting a raw material prepared by mixing a Zn source and a Se source by a continuous injection method was coated on the dot surface. Subsequently, the surface of the first shell portion was coated with a second shell portion made of ZnS synthesized by reacting a ZnS raw material by a continuous injection method. A predetermined amount (several tens μL) of the toluene / dispersion of the CdSe-based quantum dots having the core / shell structure thus generated is injected into each well of a glass microwell plate (capacity: 1.5 mL × 96 wells). (Step ST2). CdSe quantum dots have the same concentration in all wells.

Next, a surface modification treatment was performed on each CdSe-based quantum dot (step ST3). Here, the surface modified species used were two types of fluorobenzenethiol (C ₆ H ₄ F-SH, C ₆ F ₅ -SH) and one type of fluoroalkane alcohol ((C ₆ F ₁₃ ) (C ₂ H ₄ ) OH), one kind of perfluorocarboxylic acid ((C ₇ F ₁₅ ) COOH), one kind of fluoroalkanethiol ((C ₈ F ₁₇ ) (C ₂ H ₄ ) SH), fluoroalkaneamine 2 Type ((C ₈ F ₁₇ ) (C ₃ H ₆ ) NH ₂ , (C ₇ F ₁₅ ) (CH ₂ ) NH ₂ ), one type of fluoroalkane ester type ((C ₆ F ₁₃ ) (C ₂ H ₄ ) A total of eight types of OCOC (CH ₂ ) CH ₃ ) were used. In addition, the concentration of the surface modifier was 5%, 10%, and 20%. Further, three types of toluene concentrations of 3%, 10% and 20% were used during the surface modification treatment. All concentrations are% by mass. Hexafluorometa-xylene was used as a solvent for the surface modifier.

  Next, incubation was performed. The incubation temperature at this time was set to 40 ° C. The incubation time was 3 hours or 24 hours.

  Subsequently, toluene was added as an aggregating agent (step ST4), and the supernatant was removed by aggregation and sedimentation (step ST5).

  The surface-modified CdSe-based quantum dots thus obtained were mixed with hexafluorometa-xylene as a dispersion medium to obtain an evaluation sample (step ST6).

  Then, visible-ultraviolet absorption spectroscopy and fluorescence spectroscopy were performed using a microplate reader to evaluate the dispersibility and fluorescence properties of the quantum dots.

  In the above experiment, at the time of sample preparation, the concentration of the quantum dots is adjusted so as to be the same under each experimental condition, so that each evaluation sample can be compared with each other.

  In this experiment, quantum dots dispersed in toluene (without surface modification treatment) were used as reference samples, and each evaluation sample was evaluated relative to the reference sample.

  First, a baseline and an absorption peak were examined from an absorption spectrum obtained by visible-ultraviolet absorption spectroscopy. Table 1 below shows the evaluation results of the dispersibility of each evaluation sample when the incubation time was 3 hours. Table 2 shows the evaluation results of the dispersibility of each evaluation sample when the incubation time was 24 hours.

  In Tables 1 and 2, the vertical axis indicates the type of the added surface modifier, and the upper horizontal axis indicates the toluene concentration (0% toluene, 3% toluene, 10% toluene) during the surface modification treatment. And 30% toluene). Numerical values of 5%, 10% and 20% shown in the lower part of the horizontal axis indicate the concentration of the surface modifier.

  △ shown in Tables 1 and 2 indicates that the baseline was higher than the reference sample. An increase in the baseline indicates that the quantum dots are not well dispersed in the dispersion medium and are in an aggregated state.

  In addition, X shown in Tables 1 and 2 indicates a state in which the quantum dot was dissolved or the peak disappeared due to segregation of the quantum dot due to phase separation and severe aggregation.

  On the other hand, ○ shown in Tables 1 and 2 indicates an evaluation sample having a baseline equal to or lower than that of the reference sample and having an absorption peak equal to or higher than that of the reference sample.

  As shown in Tables 1 and 2, by adjusting the toluene concentration and the concentration of the surface modifier for each of the eight surface modifiers, the dispersion medium was maintained while maintaining the absorption spectrum of the reference sample or higher. Have been found that can be properly dispersed in hexafluorometa-xylene.

  Further, according to the experimental results shown in Tables 1 and 2, it is preferable to set the incubation time within 24 hours. Even if the incubation time is set to about 3 hours, it is more preferable to set the incubation time to 3 hours or less in order to shorten the evaluation time because preferable dispersibility is obtained.

  Next, the fluorescence intensity was examined from the fluorescence spectrum obtained by the fluorescence spectroscopy. Table 3 below shows the evaluation results of the fluorescence characteristics of each evaluation sample when the incubation time was 3 hours. Table 4 shows the evaluation results of the fluorescence intensity of each evaluation sample when the incubation time was 24 hours.

  In Tables 3 and 4, the vertical axis indicates the type of the added surface modifier, and the upper row indicates the toluene concentration (0% toluene, 3% toluene, 10% toluene) during the surface modification treatment. And 30% toluene). Numerical values of 5%, 10% and 20% shown in the lower part of the horizontal axis indicate the concentration of the surface modifier.

  △ shown in Tables 3 and 4 indicates the same level of fluorescence intensity as the reference sample. In addition, X shown in Tables 3 and 4 indicates that the fluorescence intensity is lower than that of the reference sample. In Tables 3 and 4, ○ indicates that the fluorescence intensity is higher than that of the reference sample.

As shown in Tables 3 and 4, pentafluorobenzenethiol (C ₆ F ₅ -SH) and 4,4,5,5,6,6,7,7,8,8,9,9,10, 10,10 heptadecafluoro undecyl amine _{((C 8 F 17) (} C 3 H 6) NH 2) were both found not to emit light.

Further, as shown in Tables 1 to 4, fluorobenzenethiol (C ₆ H ₄ F-SH) has a toluene concentration of 30% regardless of the incubation time of 3 hours or 24 hours, and the surface modifier It was found that the dispersibility and the fluorescence intensity were excellent when the concentration was 5% to 20%.

As shown in Tables 1 to 4, 3,3,4,4,5,5,6,6,7,7,8,8-tridecafluoro-1-octanol ((C ₆ F ₁₃ ) (C ₂ H ₄ ) OH) shows the dispersibility and the fluorescence intensity depending on the condition that the toluene concentration is 30% and the surface modifier concentration is 5% to 20% regardless of the incubation time of 3 hours or 24 hours. Was found to be excellent.

Further, as shown in Tables 1 to 4, perfluorooctanoic acid ((C ₇ F ₁₅ ) COOH) had a toluene concentration of 30% regardless of the incubation time of 3 hours or 24 hours, and had a surface modified property. It was found that the dispersibility and the fluorescence intensity were excellent when the agent concentration was 5%.

Further, as shown in Tables 1 to 4, 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluoro- 1- decanethiol _{((C 8 F 17) (} C 2 H 4) SH) is the incubation time is 3 hours, regardless of the 24 hours, a 30% toluene concentration, the surface modifier concentration of 5% It was found that the dispersibility and the fluorescence intensity were excellent depending on the conditions.

Further, as shown in Tables 1 and 3, 2,2,3,3,4,4,5,5,6,6,7,7,8,8,8,8-pentadecafluorooctylamine ((C ₇ F ₁₅ ) (CH ₂ ) NH ₂ ) has a toluene concentration of 3% and a surface modifier concentration of 5% or 10% regardless of the incubation time of 3 hours or 24 hours, or Dispersibility and fluorescence intensity under the conditions of a toluene concentration of 10% and a surface modifier concentration of 10% or 20%, or under a condition of a toluene concentration of 30% and a surface modifier concentration of 20%. Was found to be excellent.

As described above, when pentadecafluorooctylamine ((C ₇ F ₁₅ ) (CH ₂ ) NH ₂ ) is used, surface modification is performed in a wide range from a low toluene concentration of about 3% to a toluene concentration of about 30%. It has been found that by adjusting the concentration of the bulking agent within the range of about 5% to 20%, it is possible to uniformly disperse in the fluorine-based solvent and obtain a strong fluorescence intensity.

Further, as shown in Tables 1 and 3, 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl propionate ((C ₆ F ₁₃ ) (C ₂ H ₄ ) OCOC (CH ₂ ) CH ₃ ), when the incubation time is 3 hours, the toluene concentration is 3% and the surface modifier concentration is 10%, or the toluene concentration is Dispersion and fluorescence intensity under conditions of 10% and a surface modifier concentration of 5% and 10%, or under conditions of a toluene concentration of 30% and a surface modifier concentration of 5% to 20%. Was found to be excellent.

Also, as shown in Tables 2 and 4, 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl propionate ((C ₆ F ₁₃ ) (C ₂ H ₄ ) OCOC (CH ₂ ) CH ₃ ) has a toluene concentration of 0% and a surface modifier concentration of 10%, or a toluene concentration of 3%, When the agent concentration is 10%, or when the toluene concentration is 10%, and when the surface modifier concentration is 5% or 10%, or when the toluene concentration is 30%, the surface modifier concentration is It was found that the dispersibility and the fluorescence intensity were excellent under the conditions of 5% to 20%.

  The time required for the above experiment and examination was slightly more than one day, and about 100 conditions could be searched. Further, in the same manner as the above-described experimental method, the dispersion of the quantum dots in the fluorine-based polymer was further examined using the quantum dots dispersed in the fluorine-based solvent. Then, it was possible to find a condition under which the particles can be dispersed in a fluoropolymer while maintaining good fluorescence intensity without aggregation of quantum dots.

  The microwell plate used in the above experiment has 96 wells (holes) arranged in a matrix. Therefore, in the experiment, the same surface modifier was injected into the wells arranged in the row direction (horizontal direction) of the matrix, and different surface modifiers were injected into the wells arranged in the column direction (vertical direction). That is, each square indicated by △ in Tables 1 to 4 above represents each well, and as shown in Tables 1 to 4, each square arranged in the horizontal direction has the same surface modifier. , And the squares arranged in the vertical direction show the experimental results with eight different surface modifiers.

  In the experiment, wells arranged in the column direction (vertical direction) of the matrix were prepared under the same surface modification conditions (other than the surface modifier type), and wells arranged in the row direction (horizontal direction) were subjected to surface modification. Conditions (other than the surface modifier type) were different. That is, as shown in Tables 1 to 4, each cell arranged in the vertical direction shows the experimental result under the same surface modification conditions (other than the type of surface modifier), and each cell arranged in the horizontal direction has a different surface. The experimental results under the modification conditions (other than the surface modifier type) are shown.

  As described above, by adjusting the surface modifying agent and the surface modifying conditions for each row or each column, management becomes easy, and labor can be effectively reduced.

[Experiment-2 on Surface Modifier for Dispersion in Fluorocarbon Solvent]
The following evaluation sample was produced using a QD solution mixed with 100 μL of toluene, after washing 3 mL of the CdSe-based quantum dot stock solution produced in Experiment-1 above with ethanol.

(Evaluation sample-1)
The QD solution was aliquoted into each 10μL injected into a plurality of accommodating portions, followed by solvent 50 [mu] L, decane thiol (fluoroalkanes thiol-based) 5 [mu] L, and, undecyl amine (fluoroalkanes amine) was placed in the order of 1 [mu] L, After being dispersed in a Vortex mixer, the mixture was filtered. Subsequently, 50 μL of a fluororesin solution was mixed and dried.

(Evaluation sample-2)
The QD solution was subdivided into 10 μL portions and injected into a plurality of storage portions. Subsequently, 5 μL of decanethiol, 1 μL of undecylamine, and 50 μL of a solvent were added in this order, dispersed with a Vortex mixer, and filtered. Subsequently, 50 μL of a fluororesin solution was mixed and dried.

  As a solvent contained in each evaluation sample, three types of Novec (registered trademark) 7200 (A), FC72 / Novec 7200 (addition ratio = 1/1) (B), and FC72 (C) were used.

Then, the absorbance, fluorescence peak, fluorescence area, area / absorbance, and toluene dispersion ratio of each evaluation sample were determined. Incidentally, FC72 _is a C _{6 F 14.} The experimental results are shown in Table 5 below.

  The toluene dispersion shown in Table 5 is a QD liquid that has not been subjected to a surface modification treatment. "1" of "1-A" shown in the column of Table 5 indicates the evaluation sample-1, and "A" indicates Novec 7200 (A) as a solvent. Other column notations are shown accordingly.

  As shown in Table 5, the evaluation sample-2 in which decanethiol was added before the undecylamine and then dispersed in the solvent was able to lower the absorbance as compared with the evaluation sample-1, and the fluorescence peak was reduced. It turned out to be equivalent.

  As described above, by using two kinds of surface modifiers of decanethiol and undecylamine in combination and adjusting the order of addition, the dispersibility in the fluorine-based resin is good, and the quantum dots (surface (Without addition of a modifying agent), a surface modification condition having a higher fluorescence intensity could be obtained easily and speedily by the screening method of the present embodiment.

[Experiment-3 on Surface Modifier for Dispersion in Fluorocarbon Solvent]
After washing 2.4 mL of the CdSe-based quantum dot stock solution generated in the above Experiment-1 with 7.2 mL of ethanol for the first time and washing with 3.2 mL of ethanol for the second time, the solution was diluted with 60 μL of toluene. The following evaluation samples were produced using the QD liquid obtained by mixing.

(Evaluation sample-3)
The QD solution is subdivided into 50 μL portions and injected into a plurality of storage portions. Subsequently, 5 μL of decanethiol, 1 μL of undecylamine, and C ₆ F ₁₄ (250 μL) (D) as a solvent are charged in this order, and Vortex. After dispersing in a mixer and centrifuging to separate layers, the lower layer was extracted and filtered. Then, it was mixed with 250 μL of a fluororesin solution, and then dried.

(Evaluation sample-4)
The QD solution is subdivided into 10 μL portions and injected into a plurality of storage portions, followed by 5 μL of decanethiol, 2 μL of undecylamine, and (C ₃ F ₇ ) ₃ N (50 μL) (E) as a solvent. The mixture was put into a Vortex mixer, dispersed, centrifuged to separate layers, and then the lower layer was extracted and filtered. Then, it was mixed with 250 μL of a fluororesin solution, and then dried.

  Then, the absorbance, absorption peak, fluorescence peak, fluorescence area, and area / absorbance of each evaluation sample were determined. The experimental results are shown in Table 6 below.

  The notations of 3 and 4 shown in Table 6 indicate the numbers of the evaluation samples. FIG. 2 is a graph showing the relationship between the wavelength of the evaluation sample and the absorbance in Experiment-3. FIG. 3 is a graph showing the relationship between the wavelength and the intensity of the evaluation sample in Experiment-3.

The experiment showed that the evaluation sample-4 using (C ₃ F ₇ ) ₃ N as the solvent had a larger fluorescent area and higher intensity than the evaluation sample-3, and the intensity reduction after drying was smaller. .

  As described above, by using two kinds of surface modifiers, decanethiol and undecylamine, and adjusting the solvent, surface modification with good dispersibility in a fluororesin and high fluorescence intensity is achieved. The conditions were easily and quickly obtained by the screening method of the present embodiment.

  In the present embodiment, as described above, after the surface modification conditions for improving the dispersibility in the CFC-based solvent are derived, the nanoparticles are manufactured based on the surface modification conditions.

  That is, the method for producing nanoparticles according to the present embodiment includes the steps of generating nanoparticles, and treating the nanoparticles with fluorobenzenethiol, fluoroalkane alcohol, perfluorocarboxylic acid, fluoroalkanethiol, A step of adding at least one type of a surface modifier of an alkaneamine type and a fluoroalkane ester type to perform a surface modification treatment on the surface of the nanoparticles.

  In the present embodiment, based on the above-described screening method, as the surface modification treatment conditions, the selection of the surface modification agent and the adjustment of the solvent concentration during the surface modification treatment and the concentration of the surface modification agent are performed. Can be. “Adjustment” includes not only the act of changing or fine-tuning based on various factors in the manufacturing process, but also the act of continuing to use the surface modifier and concentration determined by the screening method.

  In addition, determination of the type of the surface modifier, the solvent concentration during the surface modification treatment, and the concentration of the surface modifier are performed by spectroscopy of a plurality of evaluation samples having different surface modification treatment conditions in the above-described screening method. By performing analysis and evaluation, it is possible to obtain easily and appropriately.

  According to the nanoparticles of the present invention, the dispersibility in a CFC-based solvent (including a resin solution) is good. Therefore, the surface-modified nanoparticles of the present invention can be preferably applied to a sealing material for LED and the like.

Claims (5)

For the surface of the nanoparticles, two or more different types of surface modification among fluorobenzenethiol, fluoroalkane alcohol, perfluorocarboxylic acid, fluoroalkanethiol, fluoroalkaneamine, and fluoroalkaneester are used. Surface modified with a filler
Nano, characterized in that a surface modifier having decanethiol as an alkanethiol constituting a fluoroalkanethiol system and a surface modifier having undecylamine as an alkaneamine constituting a fluoroalkaneamine system are used in combination. particle. The nanoparticles according to claim 1 , wherein the nanoparticles are CdSe-based quantum dots. The nanoparticles according to claim 1 or 2 , wherein the nanoparticles are fluorescent nanoparticles. Generating nanoparticles;
For the nanoparticles, two or more different surface modifications of fluorobenzenethiol, fluoroalkane alcohol, perfluorocarboxylic acid, fluoroalkanethiol, fluoroalkaneamine, and fluoroalkaneesters are provided. Adding an agent, surface modifying the surface of the nanoparticles,
Have a,
Nanoparticles characterized by using a combination of a surface modifier having decanethiol as an alkanethiol constituting a fluoroalkanethiol system and a surface modifying agent having undecylamine as an alkaneamine constituting a fluoroalkaneamine system Manufacturing method. The method for producing nanoparticles according to claim 4, wherein the surface modifier having decanethiol is added first, and then the surface modifier having undecylamine is added.

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