Method for transferring nanoparticles from aqueous phase to organic phase

Abstract

The invention belongs to the technical field of extraction of nanoparticles in a water phase, and discloses a method for transferring nanoparticles from the water phase to an organic phase. The method comprises the following steps: mixing a nanoparticle emulsion with an organic solvent to obtain a mixed solution; sequentially washing, standing and separating the mixed solution to obtain nano particles dispersed in an organic phase; the solubility of the organic solvent in water is 10-40%; a reagent used for washing is water, and the number of times of washing is 1-3. The method can ensure that the forms of the nano particles are not damaged, and the nano particles can be kept in the same dispersion state before and after phase transfer. In addition, part of residual impurities in the water phase can be removed in the phase transfer process, and the influence of the impurities on the performance of the nanoparticles is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of extracting nanoparticles in an aqueous phase, and in particular to a method for transferring nanoparticles from an aqueous phase to an organic phase. Background Art

[0002] Polymerization reactions carried out in the aqueous phase, such as emulsion polymerization, suspension polymerization, solution polymerization, etc., are suitable for preparing polymer nanoparticles with various uses. For example, styrene-butadiene rubber prepared by emulsion polymerization can be used to toughen brittle materials, and acrylic polymers can be used in coatings; polyvinyl chloride prepared by suspension polymerization can be used for electrical insulating materials; polyacrylamide prepared by solution polymerization can be used as an additive in various fields, etc. Using water as the medium, the reaction heat during the polymerization reaction can be removed in time to stabilize and control the reaction. However, reactions carried out with water as the medium also have their own disadvantages. For example, it is more difficult to disperse particles in the aqueous phase into the organic phase. The same situation also exists in the method of preparing water-based nanoparticles by emulsification or mechanical dispersion.

[0003] By searching the published literature, it is found that there are mainly the following ways to transfer nanoparticles in the aqueous phase to the organic phase: (1) using freeze-drying technology to remove water, obtain nanoparticle powder and add it to the organic phase (such as invention patent CN105622984A, invention patent CN108264735A, etc.); (2) adding nanoparticles in the aqueous phase to the organic phase, and then removing water by distillation (such as invention patent JP2751071B2).

[0004] Generally, if it is necessary to disperse the nanoparticles dispersed in the aqueous phase in the organic phase, the water should be separated from the nanoparticles. Method (1) uses freeze-drying technology to remove water, obtain nanoparticle powder and add it to the organic phase. Generally, the particle size and morphology obtained by this method will change, and the obtained particle powder is difficult to be evenly dispersed in the organic phase and is prone to agglomeration. Method (2) Add the particles in the aqueous phase to the organic phase and then remove the water by distillation. This method is difficult to operate because the organic solvent and water are easy to form a stable emulsified suspension and are difficult to separate. In addition, it takes a lot of time and effort to remove water from the organic phase. Moreover, using this method, impurities in the aqueous phase will continue to remain in the organic phase, affecting the subsequent performance of the nanoparticles. Therefore, the art urgently needs to develop a method for transferring nanoparticles from the aqueous phase to the organic phase to ensure that this method does not destroy the morphology of the nanoparticles and that the nanoparticles transferred to the organic phase can maintain a high degree of dispersion. Summary of the invention

[0005] The purpose of the present invention is to provide a method for transferring nanoparticles from an aqueous phase to an organic phase, so as to solve the problems that the existing method for transferring nanoparticles from an aqueous phase to an organic phase causes the size and morphology of the nanoparticles to change, the nanoparticles are prone to agglomeration and poor dispersion in the organic phase, and the aqueous phase is not completely removed and impurities exist, which affects subsequent use.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] The present invention provides a method for transferring nanoparticles from an aqueous phase to an organic phase, comprising the following steps:

[0008] The nanoparticle emulsion and the organic solvent are mixed to obtain a mixed solution; the mixed solution is sequentially washed, allowed to stand and separated to obtain nanoparticles dispersed in the organic phase;

[0009] The solubility of the organic solvent in water is 10 to 40%;

[0010] The reagent used for the washing is water, and the number of washing times is 1 to 3 times.

[0011] Preferably, in the nanoparticle emulsion, the concentration of the nanoparticles is 25-45 wt %.

[0012] Preferably, the organic solvent is one or more of ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone, ethanol, tetrahydrofuran, benzene, toluene and chloroform.

[0013] Preferably, the mass of the organic solvent is 0.5 to 6 times the mass of the nanoparticles in the nanoparticle emulsion.

[0014] Preferably, the mixing and washing are independently carried out under stirring conditions, and the stirring speed is independently 150-450 r / min.

[0015] Preferably, the specific step of washing is: mixing the mixed liquid and water and stirring.

[0016] Preferably, the mass of water used for the single washing is 0.3 to 3.5 times the mass of the organic solvent; and the time for the single washing is independently 20 to 40 minutes.

[0017] Preferably, the standing temperature is 20-30° C., and the standing time is 0.5-2 h.

[0018] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0019] The method for transferring nanoparticles in an aqueous phase to an organic phase provided by the present invention not only does not destroy the morphology of the nanoparticles themselves during the phase transfer process, but also enables the nanoparticles to maintain the same dispersion state before and after the phase transfer. In addition, during the phase transfer process, some impurities remaining in the aqueous phase can be removed, reducing the impact of impurities on the performance of the nanoparticles. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0021] Figure 1 is a transmission electron microscopy image of the polymethyl methacrylate (PMMA) particle emulsion in Example 1;

[0022] Figure 2 This is a transmission electron micrograph of the organic phase after phase transfer in Example 1. DETAILED DESCRIPTION

[0023] The present invention provides a method for transferring nanoparticles from an aqueous phase to an organic phase, comprising the following steps:

[0024] The nanoparticle emulsion and the organic solvent are mixed to obtain a mixed solution; the mixed solution is sequentially washed, allowed to stand and separated to obtain nanoparticles dispersed in the organic phase;

[0025] The solubility of the organic solvent in water is 10 to 40%;

[0026] The reagent used for the washing is water, and the number of washing times is 1 to 3 times.

[0027] In the nanoparticle emulsion of the present invention, the concentration of the nanoparticles is preferably 25 to 45 wt %, and more preferably 30 to 40 wt %.

[0028] In the present invention, the nanoparticle emulsion can be prepared by any polymerization reaction polymerization using water as the medium, such as emulsion polymerization, dispersion polymerization, suspension polymerization, and solution polymerization, or by emulsifying or mechanically dispersing organic matter or polymers; in the nanoparticle emulsion, the nanoparticles include but are not limited to polymethyl methacrylate, polybutyl methacrylate, polyisooctyl acrylate, polyethyl acrylate, and polystyrene.

[0029] In the present invention, the solubility of the organic solvent in water is preferably 11 to 30%, more preferably 15 to 20%; the organic solvent is preferably one or more of ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone, ethanol, tetrahydrofuran, benzene, toluene, and chloroform;

[0030] The organic solvent used has a certain solubility in water. When the organic solvent is mixed with the nanoparticles dispersed in the aqueous phase (i.e., nanoparticle emulsion), the organic solvent can stably disperse the nanoparticles in the mixed solution of water and organic solvent, so that the nanoparticles will not coagulate and precipitate.

[0031] In the present invention, the mass of the organic solvent is preferably 0.5 to 6 times the mass of the nanoparticles in the nanoparticle emulsion, and more preferably 1 to 3 times the mass of the nanoparticles in the nanoparticle emulsion.

[0032] In the present invention, the mixing and washing are independently performed under stirring conditions, and the stirring speed is independently preferably 150 to 450 r / min, and more preferably 200 to 400 r / min.

[0033] In the present invention, the specific steps of washing are: mixing the mixed liquid and water and stirring.

[0034] In the present invention, the number of washing is preferably 2 times.

[0035] In the present invention, the mass of water used for the single washing is preferably 0.3 to 3.5 times the mass of the organic solvent, and more preferably 2 to 3.2 times the mass of the organic solvent; the time for the single washing is independently preferably 20 to 40 minutes, and more preferably 30 to 35 minutes.

[0036] In the present invention, the standing temperature is preferably 20 to 30° C., more preferably 25 to 28° C.; the standing time is preferably 0.5 to 2 h, more preferably 1 to 1.5 h.

[0037] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0038] Example 1

[0039] In a 300mL glass beaker, 40g of methyl ethyl ketone (MEK) and 25g of polymethyl methacrylate (PMMA) particle emulsion (the concentration of polymethyl methacrylate is 30wt%) were added, and the mixture was stirred at a speed of 200r / min to obtain a mixed solution. 12.5g of water was added to the mixed solution and stirred at a speed of 200r / min. The stirring was stopped after 30min. After standing at room temperature for 1h, obvious stratification was formed. The lower aqueous layer was filtered, and it was found that the nanoparticles had been successfully transferred to the organic phase, and no nanoparticles were detected in the lower aqueous layer.

[0040] The transmission electron microscopy image of the polymethyl methacrylate (PMMA) particle emulsion in this embodiment is as follows: Figure 1 As shown; the transmission electron microscopy image of the organic phase after phase transfer is shown Figure 2 shown by Figure 1 and Figure 2 It can be seen that the method of the present invention not only does not destroy the morphology of the particles themselves during the transfer process, but also allows the particles to maintain the same dispersion state before and after the phase transfer.

[0041] Example 2

[0042] A mixed solvent of 36 g of methyl ethyl ketone (MEK) and 4 g of methyl isobutyl ketone (MIBK) was added to a 300 mL glass beaker, and then 25 g of polymethyl methacrylate (PMMA) particle emulsion (the concentration of polymethyl methacrylate was 30 wt%) was added, and the mixture was stirred at a speed of 200 r / min to obtain a mixed solution; 12.5 g of water was added to the mixed solution and stirred at a speed of 200 r / min. The stirring was stopped after 30 minutes, and obvious stratification was formed after standing at room temperature for 1 hour. The lower aqueous layer was filtered, and it was found that the nanoparticles had been successfully transferred to the organic phase, and no nanoparticles were detected in the lower aqueous layer.

[0043] Example 3

[0044] In a 300mL glass beaker, 40g of methyl ethyl ketone (MEK) and 25g of polymethyl methacrylate (PMMA) particle emulsion (the concentration of polymethyl methacrylate is 30wt%) were added, and the mixture was stirred at a speed of 200r / min to be evenly mixed, and a mixed solution was obtained after being evenly stirred; 12.5g of water was added to the mixed solution and stirred at a speed of 200r / min. The stirring was stopped after 30min, and obvious stratification was formed after standing at room temperature for 1h. The lower aqueous layer was filtered; 12.5g of water was added to the upper mixture and stirred at a speed of 200r / min. The stirring was stopped after 30min, and obvious stratification was formed after standing at room temperature for 1h. The lower aqueous layer was filtered, and it was found that the nanoparticles had been successfully transferred to the organic phase, and no nanoparticles were detected in the lower aqueous layer.

[0045] Comparative Example 1

[0046] 40 g of acetone and 25 g of polymethyl methacrylate (PMMA) particle emulsion (the concentration of polymethyl methacrylate is 30 wt%) were added to a 300 mL glass beaker, and stirred at a speed of 200 r / min to mix them evenly. The polymethyl methacrylate (PMMA) particles agglomerated together to form large-area agglomerates, making stirring difficult.

[0047] Comparative Example 2

[0048] 40g of methyl isobutyl ketone (MIBK) and 25g of polymethyl methacrylate (PMMA) particle emulsion (the concentration of polymethyl methacrylate is 30wt%) were added to a 300mL glass beaker, and stirred at a speed of 200r / min to mix them evenly, and a mixed solution was obtained after stirring evenly; 12.5g of water was added to the mixed solution and stirred. After 30 minutes, the stirring was stopped, and stratification was formed. The nanoparticles still existed in the lower aqueous phase, and the particles did not appear in the organic layer, that is, the polymethyl methacrylate (PMMA) particles could not be extracted into the organic phase.

[0049] Comparative Example 3

[0050] In a 300 mL glass beaker, 40 g of methyl ethyl ketone (MEK) and 25 g of polymethyl methacrylate (PMMA) particle emulsion (the concentration of polymethyl methacrylate is 30 wt%) were added, and the mixture was stirred at a speed of 200 r / min to be uniformly mixed, and a mixed solution was obtained after uniform stirring; stirring was continued at a speed of 200 r / min for 30 min, and then the stirring was stopped and allowed to stand at room temperature for 1 h to form a uniform and stable mixture, and no obvious water layer appeared, that is, water could not be removed from the polymethyl methacrylate (PMMA) particles.

[0051] The results obtained in Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Tables 1 and 2.

[0052] Table 1 Results of Examples 1-2 and Comparative Examples 1-2

[0053]

[0054] It can be seen from Table 1 that the method of the present invention transfers the nanoparticles in the aqueous phase to the organic phase without destroying the particle morphology; from the comparison between Examples 1 to 2 and Comparative Examples 1 to 2, it can be seen that an organic solvent with a certain range of solubility is required to extract the nanoparticles in the aqueous phase into the organic phase and in addition to the organic solvent, water needs to be added to separate the layers.

[0055] Table 2 Results of Example 1, Example 3 and Comparative Example 3

[0056]

[0057]

[0058] As can be seen from Table 2, the method of the present invention transfers the nanoparticles in the aqueous phase to the organic phase without destroying the particle morphology, and can also remove some of the impurities remaining in the aqueous phase during the phase transfer process, thereby reducing the impact of impurities on the performance of the nanoparticles; from the comparison of Example 1, Example 3 and Comparative Example 3, it can be seen that increasing the number of times water is added is beneficial to reducing the content of residual impurities in the organic phase.

[0059] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for transferring nanoparticles from an aqueous phase to an organic phase, characterized in that: The steps include: The nanoparticle emulsion and the organic solvent are mixed to obtain a mixed solution; the mixed solution is sequentially washed, allowed to stand and separated to obtain nanoparticles dispersed in the organic phase; The solubility of the organic solvent in water is 10 to 40%; The reagent used for the washing is water, and the number of washing times is 1 to 3 times.

2. The method for transferring nanoparticles from an aqueous phase to an organic phase according to claim 1, characterized in that: In the nanoparticle emulsion, the concentration of the nanoparticles is 25-45wt%.

3. The method for transferring nanoparticles from an aqueous phase to an organic phase according to claim 2, characterized in that: The organic solvent is one or more of ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone, ethanol, tetrahydrofuran, benzene, toluene and chloroform.

4. The method for transferring nanoparticles from an aqueous phase to an organic phase according to any one of claims 1 to 3, characterized in that: The mass of the organic solvent is 0.5 to 6 times the mass of the nanoparticles in the nanoparticle emulsion.

5. The method for transferring nanoparticles from an aqueous phase to an organic phase according to claim 4, characterized in that: The mixing and washing are independently carried out under stirring conditions, and the stirring speed is independently 150-450 r / min.

6. The method for transferring nanoparticles from an aqueous phase to an organic phase according to claim 5, characterized in that: The specific steps of washing are: mixing the mixed liquid and water and stirring.

7. The method for transferring nanoparticles from an aqueous phase to an organic phase according to claim 6, characterized in that: The mass of water used for the single washing is 0.3 to 3.5 times the mass of the organic solvent; and the time for the single washing is independently 20 to 40 minutes.

8. The method for transferring nanoparticles from an aqueous phase to an organic phase according to claim 6 or 7, characterized in that: The standing temperature is 20-30° C., and the standing time is 0.5-2 h.

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