Method for strictly controlling and modifying the surface partition size of nano-silica particles

Abstract

The present invention relates to the field of modified nano-silica particles, and discloses a method for strictly regulating the size of surface partitions of modified nano-silica particles. The method comprises: pumping an organosilicon source solution and a catalyst solution into a microfluidic synthesis device, separating the obtained mixed solution after reaction, and obtaining nano-silica particles; contacting the particles with a hydrophilic modifier as an internal phase, contacting a hydrophobic modifier with an oil solvent as an external phase, and pumping the internal phase and the external phase into a microfluidic modification device to obtain an oil-in-water emulsion, wherein the internal phase and the external phase flow rates are 50-400 μL / h and 300-5000 μL / h, respectively, and the internal phase and the external phase mass concentrations are 0.1-5% and 0.1-5%, respectively; and the product obtained after the reaction of the oil-in-water emulsion is subjected to an oxidation reaction to obtain modified nano-silica particles. The present invention achieves precise control of the modified area of ​​the nano-silica particles by regulating the flow rates and concentrations of the internal and external phases.

Description

Technical Field

[0001] The present invention relates to the field of modified nano-silica particles, and in particular to a method for strictly regulating the size of surface partitions of modified nano-silica particles. Background Art

[0002] In recent years, the controllable interfacial activity and unique Janus properties of Janus particles at the liquid-liquid interface have sparked a research boom internationally. Compared with conventional micro-nano solid particles and traditional surfactants, Janus particles are generally hydrophilic and lipophilic, while also exhibiting higher surface activity and stronger interfacial adsorption capacity, and have extremely high development prospects for improving oil recovery.

[0003] The existing process for preparing Janus particles includes first synthesizing a silica particle matrix, and then surface modification is carried out on the silica matrix to obtain Janus particles. The sol-gel (Stober) method is mainly a commonly used method for preparing nanoparticles, including adding vinyltriethoxysilane and a strong alkaline solution into a reaction vessel to react, the obtained reactant is centrifuged, washed and dried to obtain nano-silica particles, and then the nano-silica and a hydrophilic modifier and a hydrophobic modifier are added into the reaction vessel to mix, and the obtained mixed solution is oxidized to obtain modified silica particles. The method is simple and easy to implement, and has strong operability, and can complete the surface modification of nanoparticles, but the surface modification of the nanoparticles obtained belongs to random modification, and the surface modification partition and the corresponding size cannot be strictly controlled, and the morphology and size control difficulty are large, and the ability of its control interface cannot be controlled.

[0004] Microfluidics is a technology that enables precise control of fluids at the microscale. It crosslinks and solidifies droplets containing different substances, pre-prepared using a microfluidic chip, to produce micro- and nanostructured silica particles. Compared to traditional microparticle synthesis techniques, microfluidics offers advantages in material synthesis, including reduced sample usage, controllable volumes of each phase, continuous automated reactions, precise control of synthesis conditions, and excellent reproducibility. However, existing microfluidics technologies are primarily used to synthesize micron-sized silica particles, and currently, the preparation of Janus nano-silica particles mostly relies on templates, which limits their practical application. Furthermore, there is a lack of technology for precisely modifying the surface of nano-silica particles using microfluidics.

[0005] Therefore, there is an urgent need to develop a method that can strictly control the size of the surface partitions of modified nano-silica particles, so that the surface of the synthesized modified nano-silica particles has a modifiable area of ​​a specific size, thereby improving the ability of nano-silica particles to regulate interfacial tension, opening up new paths for the application of nanotechnology in oil fields, and having important significance for the production practice of low permeability oil reservoir development. Summary of the Invention

[0006] The present invention aims to overcome the problem in existing methods for preparing Janus nano-silica particles that the surface modification area of ​​the nano-silica particles cannot be precisely controlled, and to provide a method for strictly controlling the size of surface partitions of modified nano-silica particles. This method utilizes microfluidic technology to synthesize nano-silica particles and perform surface modification on the nano-silica particles based on the microfluidic technology. By regulating the flow rates and concentrations of the internal and external phases, precise control of the modified area of ​​the nano-silica particles is achieved. The resulting modified nano-silica particles exhibit significantly enhanced interfacial activity, effectively reducing interfacial tension.

[0007] In order to achieve the above object, the present invention provides a method for regulating and modifying the surface partition size of nano-silica particles, the method comprising the following steps:

[0008] (1) pumping an organosilicon source solution and a catalyst solution into a microfluidic synthesis device respectively for mixing to obtain a mixed solution;

[0009] (2) subjecting the mixed solution to a first reaction, and separating the obtained first reaction product to obtain nano-silica particles;

[0010] (3) contacting the nano-silica particles with a hydrophilic modifier as an inner phase, contacting the hydrophobic modifier with an oil solvent as an outer phase, and pumping the inner phase and the outer phase into a microfluidic modification device respectively to obtain a water-in-oil emulsion, wherein the flow rate of the inner phase is 50-400 μL / h, and the flow rate of the outer phase is 300-5000 μL / h; performing a second reaction on the water-in-oil emulsion to obtain a second reaction product;

[0011] (4) contacting the second reaction product with an oxidant to perform an oxidation reaction to obtain the modified nano-silica particles;

[0012] Wherein, the concentration of the inner phase is 0.1-5wt%, and the concentration of the outer phase is 0.1-5wt%.

[0013] Preferably, the ratio of the concentration of the inner phase to the concentration of the outer phase is 1:1-2.

[0014] Preferably, the ratio of the flow rate of the inner phase to the flow rate of the outer phase is 1:3-4.

[0015] Preferably, the conditions of the second reaction include: the temperature of the second reaction is 40-80° C., preferably 50-60° C.; and the time of the second reaction is 0.5-2.5 h, preferably 1-2 h.

[0016] Through the above technical solution, the present invention has the following beneficial effects:

[0017] (1) The present invention provides a method for strictly controlling the size of surface partitions of modified nano-silica particles. Nano-silica particles are synthesized using microfluidic technology, and the surface of the nano-silica particles is modified using microfluidic technology. The nano-silica particles obtained by the method have uniform particle size. The modified area of ​​the nano-silica particles is controlled by regulating the flow rate of the internal phase and the external phase and the concentration of the internal phase and the external phase, thereby achieving precise control of the surface modified area of ​​the nano-silica particles. The method is easy to operate, simple in apparatus, and fast in synthesis. The activity of the modified silica particles obtained at the interface is significantly enhanced, and the interfacial tension is effectively reduced.

[0018] (2) The present invention provides a method for strictly regulating the size of surface partitions of modified nano-silica particles, wherein a hydrophilic modifier is used as the aqueous phase in the inner phase to adjust the modified portion of the nano-silica surface, an oil solvent is used as the oil phase in the outer phase, and a hydrophobic modifier is used as the hydrophobic portion of the nano-silica particle surface. An oil-in-water emulsion is obtained through a microfluidic modification device, thereby realizing the screening of nanoparticle surface modification preparations and strictly regulating the size of surface partitions of modified nano-silica particles.

[0019] (3) The present invention provides a method for strictly controlling the size of surface partitions of modified nano-silica particles. A microfluidic modification device with a specially designed channel structure is used to control the inner phase and the outer phase to form an oil-in-water emulsion. The inner phase of a specific concentration is injected into the "inner core" of the microfluidic modification device at a specific flow rate, and the outer phase of a specific concentration is injected into the "outer ring" of the microfluidic modification device at a specific flow rate. The oil phase flows in the outer ring channel of the water phase and then converges at the focusing outlet of the "inner core" in the microfluidic modification device to form an oil-in-water emulsion. The oil-in-water emulsion is then oxidized to achieve precise control of the modified area of ​​the nano-silica particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation of the present invention.

[0021] Figure 1 Schematic diagram of the process for preparing nano-silica particles according to the present invention;

[0022] Figure 2 This is a schematic diagram of the process for preparing modified nano-silica particles according to the present invention;

[0023] Figure 3 This is a TEM image of the nano-silica particles prepared in Example 1 of the present invention;

[0024] Figure 4 1 is an infrared spectrum of the nano-silica particles and the modified nano-silica particles prepared in Example 1 of the present invention;

[0025] Figure 5 1 is a particle size distribution diagram of the modified nano-silica particles prepared in Examples 1-3 of the present invention;

[0026] Figure 6 It is a dynamic diagram of the oil-water interfacial tension of the modified nano-silica particles prepared by the present invention. DETAILED DESCRIPTION

[0027] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0028] The present invention provides a method for regulating and modifying the size of surface partitions of nano-silica particles, the method comprising the following steps:

[0029] (1) pumping an organosilicon source solution and a catalyst solution into a microfluidic synthesis device respectively for mixing to obtain a mixed solution;

[0030] (2) subjecting the mixed solution to a first reaction, and separating the obtained first reaction product to obtain nano-silica particles;

[0031] (3) contacting the nano-silica particles with a hydrophilic modifier as an inner phase, contacting the hydrophobic modifier with an oil solvent as an outer phase, and pumping the inner phase and the outer phase into a microfluidic modification device respectively to obtain a water-in-oil emulsion, wherein the flow rate of the inner phase is 50-400 μL / h, and the flow rate of the outer phase is 300-5000 μL / h; performing a second reaction on the water-in-oil emulsion to obtain a second reaction product;

[0032] (4) contacting the second reaction product with an oxidant to perform an oxidation reaction to obtain the modified nano-silica particles;

[0033] Wherein, the concentration of the inner phase is 0.1-5wt%, and the concentration of the outer phase is 0.1-5wt%.

[0034] In the present invention, nanosilica particles are synthesized using microfluidic technology and then surface-modified using microfluidic technology. The nanosilica particles obtained by this method have uniform particle size. In a specific microfluidic modification device, the modified surface area of ​​the nanosilica particles is controlled by regulating the flow rates and concentrations of the internal and external phases. The resulting modified silica particles exhibit significantly enhanced interfacial activity and effectively reduce interfacial tension, demonstrating that strict control of the surface modification area of ​​the nanosilica particles is achieved.

[0035] In the present invention, unless otherwise specified, the term "strictly" refers to controlling the size of the hydrophilic region and the size of the hydrophobic region on the surface of the modified nanoparticles.

[0036] In some embodiments of the present invention, preferably, the concentration of the inner phase is 0.1-5wt%, for example, 0.1wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, and any value in the range of any two values, more preferably 0.5-3wt%; the concentration of the outer phase is 0.1-5wt%, for example, 0.1wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, and any value in the range of any two values, more preferably 0.5-3wt%. In the present invention, controlling the concentrations of the inner and outer phases within the above ranges is beneficial to further accurately control the modified area of ​​the nano-silica particles.

[0037] In some embodiments of the present invention, preferably, the flow rate of the inner phase is 50-400 μL / h, for example, 50 μL / h, 100 μL / h, 150 μL / h, 200 μL / h, 250 μL / h, 300 μL / h, 350 μL / h, 400 μL / h, and any value in the range of any two values, more preferably 100-200 μL / h; the flow rate of the outer phase is 300- The flow rate of the inner phase and the outer phase is controlled within the above ranges, which is conducive to the precise control of the modified area of ​​the nano-silica particles.

[0038] In the present invention, the concentration of the inner phase and the concentration of the outer phase may be the same or different. Preferably, the concentration ratio of the inner phase to the outer phase is 1:1-2, for example, it may be 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2, and any value in the range consisting of any two values. In the present invention, on the basis that the concentrations of the inner phase and the outer phase meet the above ranges, the ratio of the inner phase concentration to the outer phase concentration is controlled within the above range, which is conducive to further precise control of the modified area of ​​the nano-silica particles.

[0039] In the present invention, the flow rate of the inner phase and the flow rate of the outer phase may be the same or different. Preferably, the flow rate ratio of the inner phase and the outer phase is 1:3-4, for example, it may be 1:3, 1:3.2, 1:3.4, 1:3.6, 1:3.8, 1:4, and any value in the range consisting of any two values. In the present invention, on the basis that the flow rates of the inner phase and the outer phase meet the above range, the ratio of the flow rate of the inner phase and the flow rate of the outer phase is controlled within the above range, which is conducive to further precise regulation of the modified area of ​​the nano-silica particles.

[0040] In the present invention, there is no special limiting relationship between the concentration and flow rate of the inner phase, and there is no special limiting relationship between the concentration and flow rate of the outer phase, as long as the concentration and flow rate each independently meet the aforementioned limiting conditions. Preferably, the ratio of the concentration of the inner phase to the flow rate of the inner phase is 1wt%:80-2000μL / h. Preferably, the ratio of the concentration of the outer phase to the flow rate of the outer phase is 1wt%:250-800μL / h. In the present invention, controlling the ratio of the concentration and flow rate of the inner phase and the ratio of the concentration and flow rate of the outer phase within the above-mentioned range is more conducive to accurately controlling the modified area of ​​the nano-silica particles, so that the activity of the modified nano-silica particles at the interface is significantly enhanced, thereby achieving regulation of interfacial tension.

[0041] In some embodiments of the present invention, preferably, the flow rate of pumping in the organosilicon source solution is 4000-10000 μL / h, for example, it can be 4000 μL / h, 5000 μL / h, 6000 μL / h, 7000 μL / h, 8000 μL / h, 9000 μL / h, 10000 μL / h, and any value in the range consisting of any two values, more preferably 5000-8000 μL / h; the flow rate of pumping in the catalyst solution is 4000-10000 μL / h, for example, it can be 4000 μL / h, 5000 μL / h, 6000 μL / h, 7000 μL / h, 8000 μL / h, 9000 μL / h, 10000 μL / h, and any value in the range consisting of any two values, more preferably 5000-8000 μL / h. In the present invention, the flow rates of the organic silicon source solution and the catalyst solution are controlled within the above ranges, which is beneficial to the mixing of the two solutions.

[0042] In the present invention, the flow rates of the organosilicon source solution and the catalyst solution may be the same or different. Preferably, the flow rates of the organosilicon source solution and the catalyst solution are the same.

[0043] In the present invention, the mixing time has a wide range of selection. Preferably, the mixing time is 10-20 seconds. In the present invention, the mixing time refers to the time it takes to collect the mixed solution after the two solutions pumped into the microfluidic channel stabilize.

[0044] In the present invention, the volume concentration of the organosilicon source solution has a wide selection range. Preferably, the volume solubility of the organosilicon source solution is 3-8%, more preferably 4-6%.

[0045] In the present invention, the type of the organosilicon source is not particularly limited and may be any of the various organosilicon sources commonly used in the art. Preferably, the organosilicon source is selected from n-alkane silicates having less than 10 carbon atoms in an alkane, preferably at least one selected from tetraethyl silicate, tetramethyl silicate, and tetrabutyl silicate, and more preferably tetraethyl silicate.

[0046] In the present invention, the type of solvent in the organosilicon source solution is not particularly limited, as long as it can dissolve the organosilicon source. Preferably, the solvent in the organosilicon source solution is selected from an alcohol solvent having 1 to 10 carbon atoms, preferably at least one selected from ethanol, propylene glycol, methanol, and butanol.

[0047] In the present invention, the volume concentration of the catalyst solution has a wide selection range. Preferably, the volume concentration of the catalyst solution is 1-10%, more preferably 3-8%.

[0048] In the present invention, the type of the catalyst is not particularly limited and can be any catalyst conventionally used in the art for synthesizing nano-silicon dioxide. Preferably, the catalyst is selected from ammonia and / or C2-C15 alkanol polyether, more preferably ammonia.

[0049] In the present invention, the type of the C2-C15 alkanol polyether is not particularly limited. Preferably, the C2-C15 alkanol polyether is selected from sodium laureth sulfate and / or ammonium laureth sulfate.

[0050] In the present invention, the type of solvent in the catalyst solution is not particularly limited, as long as it can dissolve and / or dilute the catalyst. Preferably, the solvent in the catalyst solution is selected from at least one of water, ethanol, propylene glycol, methanol, isopropanol and formaldehyde.

[0051] In the present invention, in step (1), the organosilicon source solution and the catalyst solution are mixed by a microfluidic synthesis device. Preferably, the microfluidic synthesis device includes a microfluidic synthesis chip, and the microfluidic synthesis chip realizes the mixing and reaction of microfluids in a confined space at the micron level. There is no particular limitation on the shape of the channel of the microfluidic synthesis chip, as long as it can mix the organosilicon source solution and the catalyst solution. Preferably, the microfluidic synthesis chip includes an S-shaped microchannel and a Y-shaped microchannel. There is no particular limitation on the source of the microfluidic synthesis chip, and it can be purchased commercially or prepared using existing technologies.

[0052] In a preferred embodiment of the present invention, Figure 1 As shown, the microfluidic synthesis chip includes an S-shaped microchannel and a Y-shaped microchannel. Solution I inlet 1 and solution II inlet 2 are connected by the Y-shaped microchannel and the S-shaped microchannel. The S-shaped microchannel is connected to the mixed solution outlet 3. The solution I inlet 1 and solution II inlet 2 are each connected to a syringe pump via polyethylene tubing. The solution outlet 3 is also connected to a mixed solution collection device via polyethylene tubing. The microfluidic synthesis chip of the present invention is beneficial for optimizing the mixing degree of the organosilicon source solution and the catalyst solution and preventing backflow.

[0053] In the present invention, the microchannel dimensions of the microfluidic synthesis chip have a wide range of options. Preferably, the diameters of the solution I inlet 1, the solution II inlet 2, and the mixed solution outlet 3 of the microfluidic synthesis chip are 0.9-1.1 mm. Preferably, the height and width of the Y-shaped microchannel of the microfluidic synthesis chip are 300-400 μm, and the height and width of the S-shaped microchannel are 300-400 μm, respectively.

[0054] In the present invention, the length of the microfluidic synthesis chip has a wide range of selection. Preferably, the length of the microfluidic synthesis chip is 50-60 mm. The length of the S-shaped channel of the present invention has a wide range of selection. Preferably, along the length of the microfluidic synthesis chip, the length of the S-shaped channel is 25-35 mm. The length of the Y-shaped channel of the present invention is not particularly limited, as long as the length of the microfluidic synthesis chip and the length of the S-shaped channel meet the above ranges.

[0055] In some embodiments of the present invention, preferably, the conditions of the first reaction include: an initial temperature of the first reaction of 20-50°C; and a first reaction time of 0.5-4h. The initial temperature of the first reaction is 20-50°C, for example, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, and any value in a range consisting of any two values, more preferably 25-35°C; the first reaction time is 0.5-4h, for example, 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, and any value in a range consisting of any two values, more preferably 1-2h. In the present invention, the organosilicon acid solution and the catalyst solution are pumped in at the aforementioned specific flow rate, and the temperature and time of the first reaction are controlled within the aforementioned ranges, which is conducive to the reaction of the organosilicon source and the catalyst in the mixed solution to obtain nano-silica particles of uniform size. Insufficient reaction time results in uneven particle size distribution of the generated nanoparticles and smaller size. Too long a time results in an increase in the particle size of the nanoparticles, resulting in a particle size that does not meet expectations. When the experimental temperature is too high or too low, the reaction nanoparticle generation rate changes, causing the obtained nanoparticle particle size to deviate.

[0056] In the present invention, in step (2), the separation method is not particularly limited and can be any solid-liquid separation method conventionally used in the art. Preferably, the separation method is centrifugal separation.

[0057] In the present invention, the centrifugal separation speed and time are not particularly limited, as long as the solid phase and liquid phase in the first reaction product can be separated to obtain a solid product. Preferably, the centrifugal separation speed is 5000-10000 rpm and the centrifugal separation time is 10-15 minutes.

[0058] In some embodiments of the present invention, preferably, the method in step (2) further comprises washing and drying the separated solid product.

[0059] In the present invention, the method and conditions of washing are not particularly limited, and the methods and conditions of washing conventionally used in the art can be adopted. Preferably, the centrifuged solid product is contacted with a detergent for washing, and then centrifuged again, and the obtained solid product is contacted with the detergent again, and this washing is repeated three times to obtain the washed solid product. The type of the detergent is not particularly limited, as long as it can dissolve the impurities in the first reaction product. For example, the detergent can be ethanol. The washing of the present invention can be carried out in an ultrasonic cleaning machine.

[0060] In the present invention, the solid product obtained after washing is preferably dried. The drying method and conditions can adopt the drying methods and conditions commonly used in the art. Preferably, the drying temperature is 60-100°C. The drying time is not particularly limited, as long as the solid product obtained after washing can be fully dried, for example, it can be 8-16 hours. The drying of the present invention can be carried out in a vacuum drying oven.

[0061] In the present invention, in step (2), preferably, the particle size of the nano-silica particles is 50-500 nm, preferably 100-200 nm. In the present invention, at the aforementioned specific flow rate, the mixed solution obtained using the microfluidic synthesis device is subjected to a first reaction under specific conditions, and the resulting nano-silica particles are uniform in size and controllable in size. In the present invention, unless otherwise specified, the particle size of the nano-silica particles is measured using TEM.

[0062] In some embodiments of the present invention, preferably, the internal phase is nano-silica particles and a hydrophilic modifier; the external phase is a hydrophobic modifier and an oil solvent. In the present invention, the hydrophilic modifier is used as the aqueous phase in the internal phase to adjust the modified portion of the nano-silica surface, the oil solvent is used as the oil phase in the external phase, and the hydrophobic modifier is used as the hydrophobic portion of the surface of the nano-silica particles. A microfluidic modification device with a specially designed channel structure is used to control the internal phase (including the aqueous phase) and the external phase (including the oil phase) to form an oil-in-water emulsion. The internal phase is pumped into the "inner core" of the microfluidic modification device, and the external phase is pumped into the "outer ring" of the microfluidic modification device, so that the oil phase flows in the outer ring channel of the aqueous phase, and then converges at the focusing outlet of the microfluidic modification device to form an oil-in-water emulsion. The method of the present invention achieves precise control of the modified area of ​​the nano-silica particles, and the activity of the modified nano-silica particles obtained at the interface is significantly enhanced, effectively reducing the interfacial tension.

[0063] In the present invention, the type of the hydrophilic modifier has a wide range of selection. Preferably, the hydrophilic modifier is selected from at least one of cocoylpropyl dimethyl tertiary amine, dodecyldimethylamine oxide, polyacrylamide, diethylenetriamine, triethylenetetramine, ethanolamine and diethanolamine, 3-mercaptopropyl triethoxysilane, 3-aminopropyl triethoxysilane and 3-chloropropyl triethoxysilane, preferably 3-mercaptopropyl triethoxysilane, 3-aminopropyl triethoxysilane and 3-chloropropyl triethoxysilane, more preferably 3-mercaptopropyl triethoxysilane.

[0064] In the present invention, the hydrophobic modifier has a wide range of options. Preferably, the hydrophobic modifier is selected from at least one of fatty acids, γ-chloropropyltriethoxysilane, and γ-methacrylamidopropyltrimethylsilane. In the present invention, the hydrophobic modifier has good solubility in the solvent, making the reaction easy to carry out.

[0065] In the present invention, the type of the fatty acid is not particularly limited and can be any fatty acid commonly used in the art. Preferably, the fatty acid is selected from at least one of lauric acid, myristic acid, palmitic acid and oleic acid.

[0066] In the present invention, the type of the oil solvent is not particularly limited. Preferably, the oil solvent is selected from at least one of normal alkanes, benzene, toluene and xylene, more preferably normal alkanes and / or toluene.

[0067] In the present invention, the type of the normal alkane is not particularly limited. Preferably, the normal alkane is selected from C5-C18 normal alkanes, more preferably at least one selected from n-hexane, n-heptane, n-octane, n-decane and n-undecane.

[0068] In the present invention, unless otherwise specified, the substances described in the present invention can be purchased commercially or prepared using existing technologies.

[0069] In the present invention, in step (3), preferably, the microfluidic modification device includes a microfluidic modification chip, and the microfluidic modification chip includes an inner microchannel and an outer microchannel, and the outer microchannel is present in the outer ring of the inner microchannel. The microchannel size of the microfluidic modification chip has a wide range of selection. Preferably, the outer microchannel diameter of the microfluidic modification chip is 200-1100 microns, and the inner microchannel diameter is 100-1000 microns. The source of the microfluidic modification chip is not particularly limited, and it can be purchased commercially or prepared using existing technology.

[0070] In a preferred embodiment of the present invention, Figure 2The microfluidic modification chip includes a first inner microchannel, a second inner microchannel, and an outer microchannel. The first inner microchannel (left side) and the second inner microchannel (right side) are arranged in sequence along the horizontal direction of the microfluidic modification chip. The focusing outlet of the first inner microchannel and the focusing inlet of the second inner microchannel are spaced 100-300 microns apart. The microfluidic modification chip of the present invention facilitates precise control of the modification area of ​​nano-silica particles.

[0071] In the present invention, the focusing outlet diameter of the first inner microchannel is not particularly limited. Preferably, the focusing outlet diameter of the first inner microchannel is 50-300 microns. In the present invention, the focusing inlet diameter of the second inner microchannel is 60-350 microns.

[0072] In some embodiments of the present invention, preferably, the conditions of the second reaction include: the second reaction temperature is 40-80°C; the second reaction time is 0.5-2.5h. The initial temperature of the second reaction is 40-80°C, for example, it can be 40°C, 50°C, 60°C, 70°C, 80°C, and any value in the range of any two numerical values, more preferably 50-60°C; the first reaction time is 0.5-2.5h, for example, it can be 0.5h, 1h, 1.5h, 2h, 2.5h, and any value in the range of any two numerical values, more preferably 1-2h. In the present invention, the specific concentration of the internal phase and the specific concentration of the external phase solution are pumped in at the aforementioned specific flow rate, and the temperature and time of the second reaction are controlled within the above range, which is conducive to the precise control of the modified area of ​​the nano-silica particles, and the activity of the modified nano-silica particles at the interface is significantly enhanced, thereby achieving the control of the interfacial tension.

[0073] In the present invention, in step (3), preferably, the second reaction is carried out under stirring. The stirring method is not particularly limited and can be various stirring methods conventionally used in the art, for example, can be at least one of magnetic stirring, mechanical stirring and glass rod stirring. The stirring speed of the present invention is not particularly limited, preferably, the stirring speed is 100-2000rpm, more preferably 400-800rpm.

[0074] In the present invention, the purpose of the oxidation reaction in step (3) is to make the second reaction product hydrophilic. Preferably, the thiol group is oxidized into a sulfonic acid group.

[0075] In the present invention, the amounts of the oxidant and the organosilicon source are within a wide range of options. Preferably, the volume ratio of the organosilicon source to the oxidant is 1:5-20, more preferably 1:10-15.

[0076] In the present invention, the type of the oxidant is not particularly limited and can be any oxidizing substance commonly used in the art. Preferably, the oxidant is selected from at least one of hydrogen peroxide, ozone and potassium permanganate.

[0077] In some embodiments of the present invention, preferably, the method in step (4) further comprises: dissolving the second reaction product in a solvent before contacting with the oxidant. Preferably, the method further comprises washing the second reaction product before dissolving.

[0078] In the present invention, the method and conditions of washing are not particularly limited, and the methods and conditions of washing conventionally used in the art can be adopted. Preferably, the second reaction product is contacted with a detergent for washing to obtain a washed reaction product. The type of the detergent is not particularly limited, as long as it can dissolve impurities in the second reaction product. For example, the detergent can be ethanol and / or water. The washing can be carried out in an ultrasonic cleaning machine.

[0079] In the present invention, the dissolution method comprises contacting the washed second reaction product with a solvent. The amount of the solvent used in the present invention has a wide range of selectability. Preferably, the volume ratio of the organosilicon source to the solvent is 1:5-20, more preferably 1:5-10. The type of solvent used in the present invention has a wide range of selectability. Preferably, the dissolution solvent is selected from at least one of ethanol, propylene glycol, and methanol.

[0080] In some embodiments of the present invention, preferably, the method in step (4) further comprises washing and drying the oxidation product obtained from the oxidation reaction to obtain the modified nano-silica particles.

[0081] In the present invention, the washing method and conditions are not particularly limited and can be those commonly used in the art. Preferably, the oxidation product is contacted with a detergent for washing to obtain a washed solid product. The type of the detergent is not particularly limited, as long as it can dissolve impurities in the oxidation product. For example, the detergent can be ethanol and / or water. The washing according to the present invention can be performed in an ultrasonic cleaning machine.

[0082] In the present invention, the solid product obtained after washing is preferably dried. The drying method and conditions can adopt the drying methods and conditions commonly used in the art. Preferably, the drying temperature is 60-80°C. The drying time is not particularly limited, as long as the solid product obtained after washing can be fully dried, for example, it can be 8-16 hours. The drying of the present invention can be carried out in a vacuum drying oven.

[0083] In some embodiments of the present invention, preferably, the oxidation reaction conditions include: oxidation reaction temperature of 50-80°C, preferably 55-65°C; oxidation reaction time of 2-6h, preferably 3-5h.

[0084] In some embodiments of the present invention, preferably, the oxidation reaction is carried out under stirring conditions, and the stirring speed is 500-1000 rpm.

[0085] According to a preferred embodiment of the present invention, the method for strictly controlling and modifying the surface partition size of nano-silica particles comprises the following steps:

[0086] (1) pumping the organosilicon source solution and the catalyst solution independently into a microfluidic synthesis device at a flow rate of 4000-10000 μL / h to mix and obtain a mixed solution;

[0087] (2) subjecting the mixed solution to a first reaction at an initial temperature of 20-50° C. for 0.5-4 h, and centrifuging the obtained first reaction product to obtain nano-silica particles with a particle size of 50-500 nm;

[0088] (3) contacting the nano-silica particles with a hydrophilic modifier as an inner phase, contacting the hydrophobic modifier with an oil solvent as an outer phase, and pumping the inner phase and the outer phase into a microfluidic modification device respectively to obtain a water-in-oil emulsion, wherein the flow rate of the inner phase is 40-400 μL / h, and the flow rate of the outer phase is 300-5000 μL / h; performing a second reaction on the water-in-oil emulsion at a temperature of 40-80° C. for 0.5-2.5 h to obtain a second reaction product;

[0089] (4) contacting the second reaction product with an oxidant to perform an oxidation reaction to obtain the modified nano-silica particles;

[0090] Wherein, the concentration of the inner phase is 0.1-5wt%, and the concentration of the outer phase is 0.1-5wt%.

[0091] The present invention will be described in detail below through examples.

[0092] The raw materials used in the following examples and comparative examples are all commercially available.

[0093] Particle size: TEM was used to test the particle size of nano-silica particles;

[0094] Infrared spectroscopy: Infrared spectrometer was used to conduct infrared spectroscopy test on nano-silica particles and modified nano-silica particles;

[0095] Particle size distribution: Dynamic light scattering (DLS) was used to test the particle size distribution of modified nano-silica particles;

[0096] Interfacial tension: An interfacial tension meter was used to test the interfacial tension between modified nano-silica particles and crude oil at a test temperature of 45°C.

[0097] Microfluidic synthesis chip: homemade, such as Figure 1 As shown, the diameters of inlet 1, inlet 2 and outlet 3 are all 1 mm, the height and width of the Y-shaped microchannel are both 300 μm, the height and width of the S-shaped microchannel are both 300 μm, the length of the microfluidic synthesis chip is 55 mm, and the length of the S-shaped channel is 30 mm.

[0098] Microfluidic modification chip: homemade, such as Figure 2 As shown, the outer microchannel diameter is 1000 μm, the inner microchannel diameter is 600 μm, the focusing outlet diameter of the first inner microchannel is 50 μm, the focusing inlet diameter of the second inner microchannel is 200 μm, and the distance between the focusing outlet of the first inner microchannel and the focusing inlet of the second inner microchannel is 150 μm.

[0099] Example 1

[0100] (1) 1.8 mL of tetraethyl silicate was dissolved in 30 mL of ethanol to obtain a tetraethyl silicate solution, and 1.8 mL of ammonia water was dissolved in 10 mL of ethanol and 6 mL of deionized water to obtain an ammonia solution. The two solutions were respectively loaded into two syringes of a microfluidic synthesis device. The tetraethyl silicate solution and the ammonia solution were respectively pumped into the microfluidic synthesis device at the same flow rate (5000 μL / h) at 25°C for mixing. After the flow rate stabilized, the mixed solution was collected and mixed for 10 seconds.

[0101] (2) the mixed solution was allowed to react at a temperature of 25° C. for 1 hour, the obtained reaction product was centrifuged at a speed of 5000 rpm for 10 minutes to obtain a solid phase product, the solid phase product was contacted with ethanol for washing, and the obtained product was dried at a temperature of 60° C. to obtain nano-silica particles;

[0102] (3) dissolving lauric acid in n-hexane as an external phase (at a concentration of 0.5 wt%), dispersing the nano-silica particles in 3-mercaptopropyltriethoxysilane as an internal phase (at a concentration of 0.5 wt%), passing the internal phase and the external phase into a microfluidic modification device at flow rates of 100 μL / h and 400 μL / h, respectively, to obtain a water-in-oil emulsion template, and collecting the water-in-oil emulsion at the end of the microfluidic modification device; stirring the water-in-oil emulsion at a temperature of 60° C. and a speed of 500 rpm for 1 h to obtain a reaction product;

[0103] (4) The reaction product was washed with ethanol and water, and then dissolved in 50 mL of ethanol. 5 mL of hydrogen peroxide was added to the solution. Under the condition of a stirring rate of 500 rpm, the oxidation temperature was controlled to be 60° C. and the oxidation reaction time was 3 h. The obtained oxidation product was washed with ethanol and water, and then dried at a temperature of 70° C. to obtain the modified nano-silica particles.

[0104] Figure 3 is a TEM image of the nano-silica particles prepared in this embodiment. Figure 3 It can be seen that the particle size of the nano-silica particles is uniform, with an average particle size of 100 nm.

[0105] Figure 4 The infrared spectra of the nano-silica particles and modified nano-silica particles prepared in this example are shown in FIG. Figure 4 (Left picture) It can be seen that at 3409cm -1 The peak at 1110 cm-1 belongs to the absorption peak of hydroxyl group. -1 The broad and strong absorption band corresponds to the asymmetric stretching vibration of Si-O-Si bond, located at 784 cm -1 The absorption peak is attributed to the symmetric stretching vibration of Si-O bond; Figure 4 (Right picture) It can be seen that at 2839cm -1 and 2959cm -1 The absorption peaks at are due to the antisymmetric and symmetric stretching of carbon-hydrogen of methyl and methylene groups.

[0106] Example 2

[0107] (1) 1.8 mL of raw material tetraethyl silicate was dissolved in 30 mL of ethanol to obtain a tetraethyl silicate solution, and 1.8 mL of ammonia water was dissolved in 10 mL of ethanol and 6 mL of deionized water to obtain an ammonia solution. The two solutions were respectively loaded into two syringes of a microfluidic synthesis device. The syringes were used to pump the tetraethyl silicate solution and the ammonia solution into the microfluidic synthesis device at the same flow rate (5000 μL / h) at 25°C for mixing. After the flow rate stabilized, the mixed solution was collected and mixed for 10 seconds.

[0108] (2) the mixed solution was allowed to react at 35° C. for 2 h, the obtained reaction product was centrifuged at 8000 rpm for 12 min to obtain a solid phase product, the solid phase product was contacted with ethanol for washing, and the obtained product was dried at 60° C. to obtain nano-silica particles;

[0109] (3) dissolving oleic acid in n-hexane as an external phase (at a concentration of 1 wt%), dispersing the nano-silica particles in 3-mercaptopropyltriethoxysilane as an internal phase (at a concentration of 1 wt%), passing the internal phase and the external phase into a microfluidic modification device at flow rates of 200 μL / h and 600 μL / h, respectively, to obtain a water-in-oil emulsion template, and collecting the water-in-oil emulsion at the end of the microfluidic modification device; stirring the water-in-oil emulsion at a temperature of 60° C. and a speed of 500 rpm for 1 h to obtain a reaction product;

[0110] (4) The reaction product was washed with ethanol and water, and then dissolved in 50 mL of ethanol. 5 mL of hydrogen peroxide was added to the solution. Under the condition of a stirring rate of 500 rpm, the oxidation temperature was controlled to be 60° C. and the oxidation reaction time was 3 h. The obtained oxidation product was washed with ethanol and water, and then dried at a temperature of 70° C. to obtain the modified nano-silica particles.

[0111] Example 3

[0112] (1) 1.8 mL of raw material tetraethyl silicate was dissolved in 30 mL of ethanol to obtain a tetraethyl silicate solution, and 1.8 mL of ammonia water was dissolved in 10 mL of ethanol and 6 mL of deionized water to obtain an ammonia solution. The two solutions were respectively loaded into two syringes of a microfluidic synthesis device. The syringes were used to pump the tetraethyl silicate solution and the ammonia solution into the microfluidic synthesis device at the same flow rate (8000 μL / h) at 25°C for mixing. After the flow rate stabilized, the mixed solution was collected and mixed for 10 seconds.

[0113] (2) the mixed solution was allowed to react at 35° C. for 2 h, the obtained reaction product was centrifuged at 10,000 rpm for 15 min to obtain a solid phase product, the solid phase product was contacted with ethanol for washing, and the obtained product was dried at 60° C. to obtain nano-silica particles;

[0114] (3) dissolving γ-chloropropyltriethoxysilane in n-hexane as an external phase (at a concentration of 3 wt%), dispersing the nano-silica particles in 3-mercaptopropyltriethoxysilane as an internal phase (at a concentration of 3 wt%), passing the internal phase and the external phase into a microfluidic modification device at flow rates of 200 μL / h and 800 μL / h, respectively, to obtain a water-in-oil emulsion template, and collecting the water-in-oil emulsion at the end of the microfluidic modification device; stirring the water-in-oil emulsion at a temperature of 60° C. and a speed of 500 rpm for 1 h to obtain a reaction product;

[0115] (4) The reaction product was washed with ethanol and water, and then dissolved in 50 mL of ethanol. 5 mL of hydrogen peroxide was added to the solution. Under the condition of a stirring rate of 500 rpm, the oxidation temperature was controlled to be 60° C. and the oxidation reaction time was 3 h. The obtained oxidation product was washed with ethanol and water, and then dried at a temperature of 70° C. to obtain the modified nano-silica particles.

[0116] Example 4

[0117] According to the method of Example 1, the difference is that

[0118] In step (3), the inner phase concentration is increased from 0.5 wt % to 1 wt %, and the outer phase concentration is increased from 0.5 wt % to 1 wt %; and the modified nano-silica particles are obtained.

[0119] Example 5

[0120] According to the method of Example 2, the difference is that

[0121] In step (3), the inner phase concentration is increased from 0.5 wt % to 2 wt %, and the outer phase concentration is increased from 0.5 wt % to 2 wt %; and the modified nano-silica particles are obtained.

[0122] Example 6

[0123] The method described in Example 3 is as follows, except that

[0124] In step (1), the time for collecting the mixed solution was increased from 10 s to 20 s;

[0125] In step (3), the reaction time is reduced from 2 h to 1 h; and the modified nano-silica particles are obtained.

[0126] Example 7

[0127] According to the method of Example 1, the difference is that

[0128] In step (3), the flow rate of the inner phase is reduced from 100 μL / h to 50 μL / h, and the flow rate of the outer phase is reduced from 400 μL / h to 300 μL / h; and the modified nano-silica particles are obtained.

[0129] Example 8

[0130] According to the method of Example 1, the difference is that

[0131] In step (3), the flow rate of the external phase is reduced from 400 μL / h to 300 μL / h; the concentration of the external phase is reduced from 0.5 wt % to 0.1 wt %; and the modified nano-silica particles are obtained.

[0132] Example 9

[0133] According to the method of Example 1, the difference is that

[0134] In step (3), the flow rate of the inner phase is reduced from 100 μL / h to 50 μL / h; the concentration of the inner phase is reduced from 0.5 wt % to 0.2 wt %; and the modified nano-silica particles are obtained.

[0135] Example 10

[0136] According to the method of Example 1, the difference is that

[0137] In step (3), the flow rate of the inner phase is increased from 100 μL / h to 150 μL / h, and the flow rate of the outer phase is increased from 400 μL / h to 600 μL / h; the concentration of the inner phase is increased from 0.5 wt% to 1.6 wt%, and the concentration of the outer phase is increased from 0.5 wt% to 3.5 wt%; and the modified nano-silica particles are obtained.

[0138] Example 11

[0139] The method described in Example 1 is as follows, except that

[0140] In step (1), the flow rate of the tetraethyl silicate solution and the ammonia solution was reduced from 5000 μL / h to 4000 μL / h;

[0141] In step (2), the reaction temperature is increased from 25° C. to 40° C., and the reaction time is increased from 1 h to 4 h; and the modified nano-silica particles are obtained.

[0142] Example 12

[0143] The method described in Example 1 is as follows, except that

[0144] In step (3), an equal amount of n-hexane is replaced with n-decane to obtain the modified nano-silica particles.

[0145] Comparative Example 1

[0146] According to the method of Example 1, the difference is that

[0147] In step (3), the flow rate of the inner phase is reduced from 100 μL / h to 45 μL / h; the flow rate of the outer phase is reduced from 400 μL / h to 200 μL / h; and the modified nano-silica particles are obtained.

[0148] Comparative Example 2

[0149] According to the method of Example 1, the difference is that

[0150] In step (3), the concentration of the inner phase is reduced from 0.5wt% to 0.05wt%; and the modified nano-silica particles are obtained.

[0151] Comparative Example 3

[0152] According to the method of Example 1, the difference is that

[0153] In step (3), the flow rate of the external phase is reduced from 400 μL / h to 200 μL / h; the concentration of the external phase is reduced from 0.5 wt % to 0.05 wt %; and the modified nano-silica particles are obtained.

[0154] Comparative Example 4

[0155] According to the method of Example 2, the difference is that

[0156] In step (3), the flow rate of the internal phase is reduced from 200 μL / h to 50 μL / h; the concentration of the internal phase is reduced from 1 wt % to 0.05 wt %; and the modified nano-silica particles are obtained.

[0157] Comparative Example 5

[0158] The method of Example 3 is followed, except that

[0159] In step (3), the flow rate of the internal phase is reduced from 200 μL / h to 50 μL / h; the concentration of the internal phase is reduced from 3 wt % to 0.05 wt %; and the modified nano-silica particles are obtained.

[0160] Test Case

[0161] The nano-silica particles prepared in the examples and comparative examples were tested for particle size using TEM. The test results are shown in Table 1.

[0162] The modified nano-silica particles prepared in the examples and comparative examples were subjected to interfacial tension tests. The test method included mixing crude oil and kerosene amine in a mass ratio of 1:1 to obtain a mixed oil, wherein the crude oil had a viscosity of 8.2 mPa / s and a density of 0.84 g / cm 3 The modified nano-silica particles were mixed with the mixed oil and formation water at a volume ratio of 1:200 to form an oil-water emulsion, wherein the concentrations of the modified nano-silica particles were 0.05 wt% and 0.005 wt%, respectively. The interfacial tension between the modified nano-silica particles and crude oil was tested using an interfacial tension meter at a temperature of 45°C. The test results are shown in Table 1.

[0163] Table 1

[0164]

[0165]

[0166] The results in Table 1 show that the modified nano-silica particles prepared by the method provided by the present invention have an average particle size of 50-250 nm and are uniform in size. When the average particle size of the modified nano-silica particles is 50-120 nm, the interfacial tension of the oil-water emulsion prepared from the modified nano-silica particles is 2-7 mN / m; when the average particle size of the modified nano-silica particles is 120-180 nm, the interfacial tension of the oil-water emulsion prepared from the modified nano-silica particles is 5-9 mN / m; when the average particle size of the modified nano-silica particles is 180-250 nm, the interfacial tension of the oil-water emulsion prepared from the modified nano-silica particles is 7-13 mN / m. The modified nano-silica particles prepared by the method provided by the present invention have significantly enhanced activity at the interface, effectively reduced interfacial tension, and achieved strict control of the surface partition size of the modified nano-silica particles.

[0167] Figure 5 is the particle size distribution diagram of the modified nano-silica particles prepared in Example 1-3, Figure 5 It can be seen that the particle size of the modified nano-silica particles prepared in Example 1 is concentrated in the range of 80-100 nm, the particle size of the modified nano-silica particles prepared in Example 2 is concentrated in the range of 130-150 nm, and the particle size of the modified nano-silica particles prepared in Example 3 is concentrated in the range of 200-220 nm, and the sizes are uniform.

[0168] Figure 6 This is a dynamic diagram of the oil-water interfacial tension of the modified nano-silica particles prepared by the present invention. Figure 6 It can be seen that when the concentration of the modified nano-silica particles in the prepared oil-water emulsion is 0.05wt%, the oil-water interfacial tension of the oil-water emulsion prepared using the modified nano-silica particles prepared in Example 1 (Ianus1), Example 5 (Ianus2) and Example 6 (Ianus3) is low, and the interfacial tensions after stabilization are 3.1mN / m, 7.9mN / m and 12.1mN / m, respectively; when the concentration of the modified nano-silica particles in the prepared oil-water emulsion is reduced from 0.05wt% to 0.005wt%, the oil-water interfacial tension of the oil-water emulsion increases relatively, and the interfacial tension after relative stabilization is 17.3mN / m; when no modified nano-silica particles are added to the prepared oil-water emulsion, the oil-water interfacial tension is higher.

[0169] Combining Examples 1-6 and Table 1, it can be seen that when the average particle size of the prepared modified nano-silica particles is the same, the interfacial tension of Examples 1-3 is lower, indicating that the degree of modification of the modified area of ​​the nano-silica particles is different, thereby achieving precise control of the modified area of ​​the nano-silica particles.

[0170] Combined with the results of Example 1, Examples 7-12 and Table 1, it can be seen that compared with Example 1, the flow rates of the internal phase and the external phase, and the flow rate ratio of the internal phase and the external phase in Example 7 are not within the preferred range provided by the present invention, the concentration of the external phase and the flow rate of the external phase, and the concentration ratio of the internal phase and the external phase in Example 8 are not within the preferred range provided by the present invention, the concentration of the internal phase and the flow rate of the internal phase, as well as the flow rate ratio and concentration ratio of the internal phase and the external phase in Example 9 are not within the preferred range provided by the present invention, and the internal and external phase flow rate ratio in Example 10 is not within the preferred range provided by the present invention, resulting in different surface modification areas of the modified nano-silica particles and increased interfacial tension; the flow rate of the raw material solution pumped into Example 11 and the temperature and time of the first reaction are not within the preferred range provided by the present invention, resulting in a slightly lower uniformity of the particle size distribution of the prepared nano-silica particles relative to Example 1, thereby resulting in different surface modification areas of the modified nano-silica particles, and increased interfacial tension when the average particle size of the prepared modified nano-silica particles is the same.

[0171] Combining the results of Examples 1-3, Comparative Examples 1-5 and Table 1, it can be seen that when the average particle size of the modified nano-silica particles prepared in Comparative Examples 1-5 is the same as that in Examples 1-3, the interfacial tension increases. Since the particle size distribution of the modified nano-silica particles obtained in Comparative Examples 1-5 is uneven and relatively dispersed, the modified area is uneven, and the arrangement of the nano-silica particles at the oil-water interface is uneven, resulting in an increase in interfacial tension.

[0172] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for regulating and modifying the surface partition size of nano-silica particles, characterized in that: The method comprises the following steps: (1) Pumping an organosilicon source solution and a catalyst solution into a microfluidic synthesis device respectively for mixing to obtain a mixed solution; the flow rate of the pumped-in organosilicon source solution is 4000-10000 μL / h, and the flow rate of the pumped-in catalyst solution is 4000-10000 μL / h; (2) subjecting the mixed solution to a first reaction, and separating the obtained first reaction product to obtain nano-silica particles, wherein the particle size of the nano-silica particles is 50-500 nm; (3) contacting the nano-silica particles with a hydrophilic modifier as an inner phase, contacting the hydrophobic modifier with an oil solvent as an outer phase, and pumping the inner phase and the outer phase into a microfluidic modification device respectively to obtain a water-in-oil emulsion, wherein the flow rate of the inner phase is 50-400 μL / h, and the flow rate of the outer phase is 300-5000 μL / h; performing a second reaction on the water-in-oil emulsion to obtain a second reaction product; The hydrophilic modifier is 3-mercaptopropyltriethoxysilane; the hydrophobic modifier is selected from at least one of fatty acids, γ-chloropropyltriethoxysilane and γ-methacrylamidopropyltrimethylsilane; the oil solvent is selected from at least one of normal alkanes, benzene, toluene and xylene; (4) contacting the second reaction product with an oxidant to perform an oxidation reaction to obtain the modified nano-silica particles; Wherein, the concentration of the inner phase is 0.1-5wt%, and the concentration of the outer phase is 0.1-5wt%.

2. The method according to claim 1, wherein The concentration of the inner phase is 0.5-3 wt %, and the concentration of the outer phase is 0.5-3 wt %.

3. The method according to claim 1, wherein The flow rate of the inner phase is 100-200 μL / h, and the flow rate of the outer phase is 400-1000 μL / h.

4. The method according to claim 1, wherein The ratio of the concentration of the inner phase to the concentration of the outer phase is 1:1-2.

5. The method according to claim 1, wherein The ratio of the flow rate of the inner phase to the flow rate of the outer phase is 1:3-4.

6. The method according to claim 1, wherein The conditions of the second reaction include: the temperature of the second reaction is 40-80° C.; and the time of the second reaction is 0.5-2.5 h.

7. The method according to claim 6, wherein: The conditions of the second reaction include: the temperature of the second reaction is 50-60° C.; and the time of the second reaction is 1-2 h.

8. The method according to claim 1, wherein The second reaction is carried out under stirring conditions, and the stirring speed is 100-2000 rpm.

9. The method according to claim 8, wherein The second reaction is carried out under stirring conditions at a stirring speed of 400-800 rpm.

10. The method according to claim 1, wherein The conditions of the first reaction include: the initial temperature of the first reaction is 20-50° C.; and the first reaction time is 0.5-4 h.

11. The method according to claim 1, wherein The conditions of the first reaction include: the initial temperature of the first reaction is 25-35° C.; and the first reaction time is 1-2 h.

12. The method according to claim 1, wherein The separation method is centrifugal separation.

13. The method according to claim 12, wherein: The centrifugal separation speed is 5000-10000 rpm; the centrifugal separation time is 10-15 minutes.

14. The method according to claim 12, wherein: The method of step (2) further comprises washing and drying the separated solid product.

15. The method according to claim 14, wherein The drying temperature is 60-100°C.

16. The method according to claim 1, wherein The flow rate of the organic silicon source solution pumped in is 5000-8000 μL / h; the flow rate of the catalyst solution pumped in is 5000-8000 μL / h.

17. The method according to claim 1, wherein The mixing time is 10-20s.

18. The method according to claim 1, wherein The volume solubility of the organosilicon source solution is 3-8%.

19. The method according to claim 18, wherein The volume solubility of the organosilicon source solution is 4-6%.

20. The method according to claim 1, wherein The organosilicon source is selected from n-alkane silicates having less than 10 carbon atoms in alkanes.

21. The method according to claim 20, wherein The organic silicon source is selected from at least one of tetraethyl silicate, tetramethyl silicate and tetrabutyl silicate.

22. The method according to claim 1, wherein The solvent in the organic silicon source solution is selected from alcohol solvents having 1 to 10 carbon atoms.

23. The method according to claim 22, wherein The solvent in the organic silicon source solution is selected from at least one of ethanol, propylene glycol, methanol and butanol.

24. The method according to claim 1, wherein The volume concentration of the catalyst solution is 1-10%.

25. The method according to claim 24, wherein The volume concentration of the catalyst solution is 3-8%.

26. The method according to claim 1, wherein The catalyst is selected from ammonia water and / or C2-C15 alkanol polyether.

27. The method according to claim 26, wherein The C2-C15 alkanol polyether is selected from sodium lauryl polyether sulfate and / or ammonium lauryl polyether sulfate.

28. The method according to claim 1, wherein The solvent in the catalyst solution is selected from at least one of water, ethanol, propylene glycol, methanol, isopropanol and formaldehyde.

29. The method according to claim 1, wherein The fatty acid is selected from at least one of lauric acid, myristic acid, palmitic acid and oleic acid.

30. The method of claim 1, wherein The normal alkanes are selected from C5-C18 normal alkanes.

31. The method according to claim 30, wherein The normal alkane is selected from at least one of normal hexane, normal heptane, normal octane, normal decane and normal undecane.

32. The method of claim 1, wherein The conditions of the oxidation reaction include: oxidation reaction temperature of 50-80° C.; oxidation reaction time of 2-6 hours.

33. The method according to claim 32, wherein The conditions of the oxidation reaction include: oxidation reaction temperature of 55-65° C.; oxidation reaction time of 3-5 h.

34. The method of claim 1, wherein The oxidation reaction is carried out under stirring conditions, and the stirring speed is 500-1000 rpm.

35. The method of claim 1, wherein The volume ratio of the organosilicon source to the oxidant is 1:5-20.

36. The method according to claim 35, wherein The volume ratio of the organosilicon source to the oxidant is 1:10-15.

37. The method according to claim 35, wherein The oxidant is selected from at least one of hydrogen peroxide, ozone and potassium permanganate.

38. The method of claim 1, wherein The method of step (4) further includes: dissolving the second reaction product in a solvent before contacting with the oxidant.

39. The method according to claim 38, wherein The volume ratio of the organic silicon source to the solvent is 1:5-20.

40. The method of claim 39, wherein The volume ratio of the organic silicon source to the solvent is 1:5-10.

41. The method of claim 1, wherein The method further comprises washing and drying the oxidation product obtained by the oxidation reaction to obtain the modified nano-silica particles.

42. The method according to claim 41, wherein The drying temperature is 60-80°C.

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