Hemispherical Janus-SiO2 particle additive for emulsion as well as preparation method and application of hemispherical Janus-SiO2 particle additive
By preparing hemispherical Janus-SiO2 particle additives, the problems of insufficient lubricity and stability of emulsions were solved, and the lubrication performance and dispersion stability were improved, which is suitable for improving emulsions in metal cold rolling processes.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-29
- Publication Date
- 2026-03-13
AI Technical Summary
Existing emulsions struggle to balance lubrication performance and emulsion stability, exhibiting problems such as poor lubrication and insufficient stability.
Hemispherical Janus-SiO2 particle additives are used. During the preparation process, one end of the SiO2 particles is hydrophobically modified and the first phase microspheres are removed, so that one side is hydrophilic and the other side is hydrophobic, which enhances the compatibility and interfacial adsorption capacity of the oil and water phases.
It achieves a synergistic improvement in lubrication performance and dispersion stability, effectively prevents the aggregation and sedimentation of oil or water phases, reduces the coefficient of friction and workpiece wear rate, and improves the dispersion uniformity and static stability of emulsion.
Smart Images
Figure CN121648842A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the technical field of metalworking lubricating materials and Pickering emulsion stabilizers, specifically relating to hemispherical Janus-SiO2 particle additives for emulsions, their preparation methods, and applications. Background Technology
[0002] Cold rolling is a key process for the precision forming of metal materials. Emulsions, as an important auxiliary medium in this process, must simultaneously possess excellent lubricity, cooling properties, and stability. Currently, emulsions have significant limitations: it is difficult to balance lubrication performance with emulsion stability; emulsion stability is relatively poor, and they are prone to stratification. Summary of the Invention
[0003] To address the shortcomings of existing emulsions in achieving both lubrication performance and emulsion stability, this invention provides a hemispherical Janus-SiO2 particle additive for emulsions, its preparation method, and its application. The asymmetry between the hydrophilic bottom and hydrophobic top of the hemispherical Janus-SiO2 particle additive enhances its compatibility with the oil and water phases of the emulsion. Simultaneously, its hydrophilic bottom can be directionally adsorbed at the metal friction interface, while its hydrophobic top can anchor the oil film, thereby achieving a synergistic improvement in lubrication performance and dispersion stability.
[0004] To achieve the above objectives, the present invention adopts the following technical solution: The preparation method of hemispherical Janus-SiO2 particle additives for emulsions includes the following steps: A composite microsphere is prepared by combining a first-phase microsphere with SiO2 particles; in the composite microsphere, the first-phase microsphere is connected to the SiO2 particles, with one end being the first-phase microsphere and the other end being the SiO2 particles, wherein the SiO2 particles are hydrophilic. The composite microspheres are hydrophobically modified to give the exposed surface of the SiO2 particles a hydrophobic layer; then the first phase microspheres are removed to expose the hydrophilic surface of the SiO2 particles, thus obtaining the hemispherical Janus-SiO2 particle additive for emulsions.
[0005] Preferably, the first phase microspheres are polystyrene microspheres.
[0006] Preferably, the preparation process of the composite microspheres includes: Styrene that has been deionized by vacuum distillation to remove the polymerization inhibitor and deionized water are added and mixed to obtain mixture A. Mixture A is heated to 70-80℃ under a protective atmosphere, and then potassium persulfate aqueous solution is added to react. After the reaction is completed, solid-liquid separation and washing are performed, and then the washing product is dispersed in anhydrous ethanol to obtain polystyrene seed ethanol dispersion. The polystyrene seed ethanol dispersion was homogenized to form a suspension. 3-aminopropyltriethoxysilane was added to the suspension for reaction, followed by solid-liquid separation and washing. The washing product was then dispersed in anhydrous ethanol to obtain an aminated PS (PS-NH2) ethanol dispersion. Anhydrous ethanol and deionized water were added to the aminated PS (PS-NH2) ethanol dispersion for dilution, and ammonia was added to adjust the pH to 8-9. Tetraethyl orthosilicate was then added, and the reaction was maintained at 35-55°C for 2-3 hours. After the reaction, solid-liquid separation, washing, and vacuum drying were performed to obtain the composite microspheres.
[0007] Preferably, for every 8-10 mL of styrene, 120-150 mL of deionized water and 5 mL of potassium persulfate aqueous solution are added, wherein the potassium persulfate aqueous solution contains 0.15-0.25 g of potassium persulfate, and the concentration of the polystyrene seed ethanol dispersion is 10-15 mg / mL. For every 20-30 mL of polystyrene seed ethanol dispersion, add 30-40 mL of anhydrous ethanol and 0.1-0.2 mL of 3-aminopropyltriethoxysilane; the concentration of the aminated PS (PS-NH2) ethanol dispersion is 5-7 mg / mL; for every 30-40 mL of the dispersion, add 15-20 mL of anhydrous ethanol, 5-8 mL of deionized water, 0.5-1 mL of 25-28 wt% ammonia, and 0.3-0.6 mL of tetraethyl orthosilicate.
[0008] Preferred method: The protective atmosphere is nitrogen; the potassium persulfate aqueous solution is added dropwise; after adding the potassium persulfate aqueous solution, the system is sealed and reacted at 245-255 rpm for 6-8 hours with stirring. After the reaction is completed, the mixture is cooled to room temperature and centrifuged at 9950-10050 rpm for 14-16 minutes. The centrifuged product is washed with deionized water 3-5 times to obtain the washed product. The polystyrene seed ethanol dispersion was homogenized by ultrasonication to form a suspension. The ultrasonic power was 290-310W, and the ultrasonication time was 14-16 min. 3-Aminopropyltriethoxysilane was added to the suspension for reaction. After solid-liquid separation and washing, the mixture was stirred at 195-205 rpm for 4-6 h, then centrifuged at 7950-8050 rpm for 9-11 min, and washed 3-5 times with anhydrous ethanol. Ammonia was added while stirring at 175-185 rpm. After the addition of tetraethyl orthosilicate, the mixture was centrifuged at 8950-9050 rpm for 9-11 min, and then washed 3-5 times with anhydrous ethanol. Vacuum drying was carried out at 38-42℃ for 7.5-8.5 h.
[0009] Preferably, the process of hydrophobic modification of the composite microspheres includes: The composite microspheres were ultrasonically dispersed in anhydrous ethanol to obtain an ethanol dispersion of composite microspheres; wherein, 0.1-0.2 g of composite microspheres were added to every 40-50 mL of anhydrous ethanol, the ultrasonic power was 290-310 W, and the ultrasonic time was 14-16 min. Dodecyltrimethoxysilane and deionized water were added to the ethanol dispersion of the composite microspheres to carry out the reaction. After the reaction, the microspheres were separated, washed, and vacuum dried to obtain hydrophobically modified composite microspheres. For every 0.1-0.2 g of composite microspheres, 0.05-0.15 mL of dodecyltrimethoxysilane and 0.5-15 mL of deionized water were added, with the dodecyltrimethoxysilane added dropwise. The reaction was stirred at a rate of 195-205 rpm for 2-3 hours. Separation was performed by centrifugation at 7950-8050 rpm for 9-11 minutes. The microspheres were washed 3-5 times with anhydrous ethanol. Vacuum drying was carried out at 38-42℃ for 5.5-6.5 hours.
[0010] Preferably, the process of removing the first phase microspheres to expose the hydrophilic surface of the SiO2 particles includes: Hydrophobically modified composite microspheres were added to tetrahydrofuran until the polystyrene microspheres were completely dissolved; then solid-liquid separation and vacuum drying were performed to obtain the hemispherical Janus-SiO2 particle additive for emulsion. For every 5-10 mL of tetrahydrofuran, 0.05-0.15 g of hydrophobically modified composite microspheres were added. After adding the hydrophobically modified composite microspheres to tetrahydrofuran, the mixture was reacted at a stirring rate of 145-155 rpm for 4-6 h. Then, the mixture was centrifuged at a stirring speed of 9950-10050 rpm for 14-16 min, the supernatant was discarded, and the mixture was washed 2-3 times with tetrahydrofuran and then 1-2 times with anhydrous ethanol. The mixture was then vacuum dried at a temperature of 38-42℃ for 5.5-6.5 h.
[0011] The present invention also provides a hemispherical Janus-SiO2 particle additive for emulsions, which is prepared by the preparation method described above.
[0012] The present invention also provides the application of the hemispherical Janus-SiO2 particle additive as described above for the preparation of emulsions.
[0013] Preferably, the process for preparing the emulsion includes: The hemispherical Janus-SiO2 particle additive for emulsion is added to a mixture of oil and water, and emulsified at a speed of 6000~8000 r / min for 30~60 min to obtain an emulsion containing hemispherical Janus-SiO2 particle additive. The amount of hemispherical Janus-SiO2 particle additive added is 1wt%~5wt% of the mass of the oil and water mixture; the volume ratio of oil to water in the oil and water mixture is (3~5):(3~5).
[0014] The present invention has the following beneficial effects: The present invention provides a method for preparing hemispherical Janus-SiO2 particle additives for emulsions. This method involves a stepwise preparation process: first, preparing composite microspheres with one end being a first-phase microsphere and the other end being a hydrophilic SiO2 particle; then, hydrophobically modifying the exposed SiO2 surface; and finally, removing the first-phase microspheres to re-expose the hydrophilic SiO2 surface. This yields a hemispherical Janus-SiO2 particle additive with one hydrophobic side and one hydrophilic side. This structure not only solves the core problem of existing emulsions' difficulty in balancing lubricity and stability, but also features a simple, controllable, and easily industrialized process. Specifically, the asymmetric amphiphilic particles prepared by this invention can simultaneously adapt to the oil-water two-phase system of emulsions, forming a stable interfacial film through directional adsorption at the oil-water interface. This effectively prevents the aggregation and sedimentation of the oil or water phase, improves the dispersion uniformity and static stability of the emulsion, and avoids stratification. At the same time, this amphiphilic structure allows the particles to be directionally adsorbed on the surface of the friction pair, with the hydrophilic end combining with water and the hydrophobic end combining with oil to form a composite lubricating film. This effectively reduces the coefficient of friction and the wear rate of the workpiece, improving the lubrication effect. Furthermore, the entire preparation process does not require complex reaction conditions or special equipment, reducing production costs while ensuring the feasibility of industrial mass production. Attached Figure Description
[0015] Figure 1 The dumbbell-shaped PS / SiO2 particles prepared in Example 1 of this invention.
[0016] Figure 2 The friction curves of the emulsions containing hemispherical Janus-SiO2 particles prepared in Examples 1-3 of this invention and Comparative Examples 1-2 are shown.
[0017] Figure 3 The average friction coefficient diagrams are shown for the emulsions containing hemispherical Janus-SiO2 particle additives prepared in Examples 1-3 of this invention and Comparative Examples 1-2.
[0018] Figure 4The images show the disc wear rates of the emulsions containing hemispherical Janus-SiO2 particles prepared in Examples 1-3 of this invention and Comparative Examples 1-2.
[0019] Figure 5 The images show the macroscopic standing images of the emulsions containing hemispherical Janus-SiO2 particles prepared in Examples 1-3 of this invention and Comparative Examples 3-4 after 30 days.
[0020] Figure 6 The emulsions containing hemispherical Janus-SiO2 particle additives prepared in Examples 1-3 of this invention and the 30-day standing emulsion ratios of Comparative Examples 3-4 are shown. Detailed Implementation
[0021] The present invention will be further described clearly and in detail below with reference to specific embodiments and the accompanying drawings. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.
[0022] The preparation process of the hemispherical Janus-SiO2 particle additive for emulsions described in this invention first involves preparing composite microspheres. The composite microspheres are approximately dumbbell-shaped. In these composite microspheres, a first-phase microsphere is connected to SiO2 particles, with one end being the first-phase microsphere and the other end being the SiO2 particles. The SiO2 particles are hydrophilic. In the following embodiments of this invention, the first-phase microspheres are polystyrene (denoted as PS) microspheres. Therefore, the prepared composite microspheres are referred to as dumbbell-shaped PS / SiO2. The obtained composite microspheres are hydrophobically modified (e.g., using dodecyltrimethoxysilane (DTMS) for hydrophobic modification). After modification, the first-phase microspheres are etched away (e.g., using tetrahydrofuran to etch away PS (i.e., polystyrene microspheres)) to obtain hemispherical Janus-SiO2 particles (the upper hemisphere of the hemispherical Janus-SiO2 particle is a DTMS hydrophobic layer, and the bottom (i.e., the part connected to the polystyrene microsphere) retains the SiO2 hydrophilic hydroxyl groups). The hemispherical Janus-SiO2 particles prepared by this invention can be used in emulsions, and the specific preparation method includes the following steps: Step 1) Add 8-10 mL of styrene (St) that has been deionized by vacuum distillation to remove polymerization inhibitors and 120-150 mL of deionized water to a 250 mL three-necked flask. Purge with nitrogen (50 mL / min) for 30 min to remove oxygen, so that the three-necked flask is in a protective atmosphere. Heat to 70-80℃ and add dropwise 0.15-0.25 g of potassium persulfate (KPS) aqueous solution purified by recrystallization (the potassium persulfate aqueous solution is obtained by dissolving potassium persulfate in 5 mL of deionized water). Seal the system and react with stirring at 250±5 rpm for 6-8 h. After the reaction is completed, cool to room temperature and centrifuge at 10000±50 rpm for 14-16 min. Wash the centrifuged product with deionized water 3-5 times. Finally, disperse the PS precipitate (i.e., polystyrene microspheres) in 50 mL of anhydrous ethanol to obtain a PS seed ethanol dispersion (concentration of 10-15 mg / mL).
[0023] Step 2) Take 20-30 mL of the PS seed ethanol dispersion obtained in Step 1), add 30-40 mL of anhydrous ethanol to dilute, and sonicate for 14-16 min (ultrasonic power of 300±10 W) to form a homogeneous suspension; add 0.1-0.2 mL of 3-aminopropyltriethoxysilane (abbreviated as APTES), and stir at 200±5 rpm for 4-6 h at room temperature; after the reaction, centrifuge at 8000±50 rpm for 9-11 min, and wash the centrifuged product 3 times with anhydrous ethanol to obtain an amino-modified PS (PS-NH2) ethanol dispersion (concentration 5-7 mg / mL).
[0024] Step 3) Add 30-40 mL of PS-NH2 ethanol dispersion, 15-20 mL of anhydrous ethanol, and 5-8 mL of deionized water to a 100 mL three-necked flask. While stirring (180±5 rpm), add 0.5-1 mL of 25wt%-28wt% ammonia water dropwise to adjust the pH to 8-9. Then, add 0.3-0.6 mL of tetraethyl orthosilicate dropwise through a constant pressure dropping funnel. After the addition is complete, raise the temperature to 35-55℃ and keep the reaction at this temperature for 2-3 h. After the reaction is complete, centrifuge at 9000±50 rpm for 9-11 min. Wash the centrifuged product with anhydrous ethanol 3-5 times and vacuum dry (vacuum drying temperature is 40±2℃, time is 7.5-8.5 h) to obtain dumbbell-shaped PS / SiO2 composite microspheres.
[0025] Step 4) Take 0.1-0.2g of dumbbell-shaped PS / SiO2 composite microspheres, disperse them in 40-50mL of anhydrous ethanol, and sonicate for 14-16min (ultrasonic power 300±10W); add 0.05-0.15mL of dodecyltrimethoxysilane (DTMS) and 0.5-15mL of deionized water (to provide water for hydrolysis), and stir at 200±5rpm for 2-3h at room temperature; after the reaction, centrifuge at 8000±50rpm for 9-11min, wash the centrifuged product with anhydrous ethanol 3-5 times, and then vacuum dry (vacuum drying temperature 40±2℃, time 5.5-6.5h) to obtain hydrophobically modified dumbbell-shaped PS / SiO2 particles (only the SiO2 exposed area of the particles is modified by DTMS, and the PS area does not react).
[0026] Step 5) Add 0.05-0.15g of hydrophobically modified dumbbell-shaped PS / SiO2 to 5-10mL of tetrahydrofuran (THF) and stir at 150±5 rpm for 4-6h at room temperature (at which point the PS is completely dissolved); then centrifuge at 10000±50rpm for 14-16min, discard the upper PS / THF solution, wash the centrifuged product with THF 2-3 times, then wash with anhydrous ethanol 1-2 times, and then vacuum dry (vacuum drying temperature is 40±2℃, time is 5.5-6.5h) to obtain hemispherical Janus-SiO2 particles (the upper hemisphere is a DTMS hydrophobic layer, and the bottom retains the SiO2 hydrophilic hydroxyl groups).
[0027] In the above-described solution of the present invention, the value before the ± sign is the set value of the relevant parameter device, and the value before the ± sign is the deviation value of the relevant parameter device. In the following embodiments and comparative examples of the present invention, these parameters are only written as the set value. It can be understood that the technical solution of the present invention is feasible within the parameter range determined by the set value and deviation value of the relevant parameter device.
[0028] The preparation process of the hemispherical Janus-SiO2 particle additive for emulsions described in this invention involves precise multi-step control, achieving synergistic optimization of structure and performance through directional synthesis and modification. Specifically, firstly, polystyrene (PS) seed dispersion is prepared using styrene (St) as a monomer, through nitrogen deoxygenation and potassium persulfate (KPS)-initiated polymerization. Then, aminated PS (PS-NH2) is obtained by modification with 3-aminopropyltriethoxysilane (APTES). Subsequently, in a weakly alkaline environment regulated by ammonia, SiO2 phase is directionally grown on the surface of PS microspheres through the hydrolysis and condensation reaction of tetraethyl orthosilicate, forming well-structured dumbbell-shaped PS / SiO2 composite microspheres. Next, the composite microspheres are hydrophobically modified using dodecyltrimethoxysilane (DTMS). DTMS reacts only with the SiO2 exposed regions and not with the PS phase, achieving selective hydrophobic modification of the SiO2 regions. Finally, the modified dumbbell-shaped PS / SiO2 composite microspheres were selectively etched with tetrahydrofuran (THF) to completely dissolve and remove the PS phase. After centrifugation, washing, and vacuum drying, hemispherical Janus-SiO2 particles with an asymmetric amphiphilic structure were finally obtained. One end of the hemispherical Janus-SiO2 particles is a hydrophobic layer formed by DTMS modification, while the other end retains the hydrophilic hydroxyl groups of SiO2 itself. This unique structural design enables it to be adapted to both oil-water two-phase systems of emulsions, laying a core foundation for subsequent improvement of emulsion performance.
[0029] The process of using the hemispherical Janus-SiO2 particle additive obtained by the above method of the present invention to prepare emulsion is as follows: The hemispherical Janus-SiO2 particle additive for the emulsion is added to a mixed solution of 15-25 ml oil and 15-25 ml water at a ratio of 1 wt% to 5 wt%. The mixture is then emulsified using a homogenizer at a speed of 6000-8000 r / min for 30-60 min to obtain an emulsion containing the hemispherical Janus-SiO2 particle additive.
[0030] This invention prepares an emulsion containing hemispherical Janus-SiO2 particle additives, suitable for cold rolling of difficult-to-machine metals. The hemispherical Janus-SiO2 particle additives, due to their upper hemisphere being a hydrophobic DTMS layer and retaining the hydrophilic hydroxyl groups of SiO2 at the bottom, can effectively adsorb at the oil-water interface, stabilizing the emulsion and preventing emulsion maturation and aggregation. Due to their unique amphiphilic properties, they can also be more effectively adsorbed in friction pairs, playing a role in friction reduction and wear resistance. This invention solves problems such as adhesion, severe wear, reduced roll life, and poor sheet surface quality in the cold rolling deformation process of difficult-to-machine metals, providing a new approach for the cold rolling of difficult-to-machine metals.
[0031] Example 1 The preparation process of the hemispherical Janus-SiO2 particle additive for emulsions in this embodiment is as follows: 1) Add 8 mL of styrene (St) that has been deionized by vacuum distillation to remove polymerization inhibitors and 120 mL of deionized water to a 250 mL three-necked flask, and purge with nitrogen (50 mL / min) to remove oxygen for 30 min; heat to 70 °C, and add 0.15 g of potassium persulfate (KPS) aqueous solution purified by recrystallization (dissolved in 5 mL of deionized water). Seal the system and react for 6 h with stirring at 250 rpm; after the reaction is complete, cool to room temperature, centrifuge at 10000 rpm for 15 min, wash the centrifuged product three times with deionized water, and finally disperse the PS precipitate in 50 mL of anhydrous ethanol to obtain a PS seed ethanol dispersion (concentration of 10 mg / mL).
[0032] 2) Take 20 mL of PS seed ethanol dispersion obtained in step 1), add 30 mL of anhydrous ethanol to dilute, and sonicate for 15 min (ultrasonic power of 300 W) to form a homogeneous suspension; add 0.1 mL of 3-aminopropyltriethoxysilane (APTES), and stir at 200 rpm for 4 h at room temperature; after the reaction, centrifuge at 8000 rpm for 10 min, and wash the centrifuged product 3 times with anhydrous ethanol to obtain aminated PS (PS-NH2) ethanol dispersion (concentration 5 mg / mL).
[0033] 3) Add 30 mL of PS-NH2 ethanol dispersion, 15 mL of anhydrous ethanol, and 5 mL of deionized water to a 100 mL three-necked flask. While stirring (180 rpm), add 0.5 mL of 28 wt% ammonia solution dropwise to adjust the pH to 9. Then, add 0.3 mL of tetraethyl orthosilicate dropwise through a constant-pressure dropping funnel. After the addition is complete, raise the temperature to 35 °C and maintain the reaction temperature for 2 h. After the reaction is complete, centrifuge at 9000 rpm for 10 min. Wash the centrifuged product three times with anhydrous ethanol, and then vacuum dry (at 40 °C for 8 h) to obtain dumbbell-shaped PS / SiO2 composite microspheres, the structure of which is shown below. Figure 1 As shown, in this composite microsphere, PS microspheres are connected to SiO2 particles, with one end being a PS microsphere and the other end being a SiO2 particle.
[0034] 4) Take 0.1 g of dumbbell-shaped PS / SiO2 composite microspheres, disperse them in 40 mL of anhydrous ethanol, and sonicate for 15 min (ultrasonic power of 300 W); add 0.05 mL of dodecyltrimethoxysilane (DTMS) and 0.5 mL of deionized water (to provide water for hydrolysis), and stir at 200 rpm for 2 h at room temperature; after the reaction, centrifuge at 8000 rpm for 10 min, wash the centrifuged product three times with anhydrous ethanol, and then vacuum dry (vacuum drying temperature of 40℃ for 6 h) to obtain hydrophobically modified dumbbell-shaped PS / SiO2 particles (only the SiO2 exposed area is modified by DTMS, and the PS area does not react).
[0035] 5) Add 0.05 g of hydrophobically modified dumbbell-shaped PS / SiO2 to 5 mL of tetrahydrofuran (THF) and stir at 150 rpm for 4 h at room temperature (at which point the PS is completely dissolved); then centrifuge at 10000 rpm for 15 min, discard the upper PS / THF solution, wash the centrifuged product twice with THF, then wash once with anhydrous ethanol, and then vacuum dry (vacuum drying temperature is 40℃, time is 6 h) to obtain hemispherical Janus-SiO2 particles (the upper hemisphere is a DTMS hydrophobic layer, and the bottom retains the SiO2 hydrophilic hydroxyl groups).
[0036] The process of using the hemispherical Janus-SiO2 particle additive obtained by the above method of the present invention to prepare emulsion is as follows: The hemispherical Janus-SiO2 particle additive for the emulsion was added to a mixed solution of 15 ml rapeseed oil and 15 ml water at a ratio of 1 wt%, and emulsified for 30 min at a speed of 6000 r / min using a homogenizer to obtain an emulsion containing the hemispherical Janus-SiO2 particle additive.
[0037] Example 2 The preparation process of the hemispherical Janus-SiO2 particle additive for emulsions in this embodiment is as follows: 1) Add 9 mL of styrene (St) that has been deionized by vacuum distillation to remove polymerization inhibitors and 135 mL of deionized water to a 250 mL three-necked flask, and purge with nitrogen (50 mL / min) to remove oxygen for 30 min; heat to 75 °C, and add 0.20 g of potassium persulfate (KPS) aqueous solution purified by recrystallization (dissolved in 5 mL of deionized water). Seal the system and react for 7 h with stirring at 250 rpm; after the reaction is complete, cool to room temperature, centrifuge at 10000 rpm for 15 min, wash the centrifuged product with deionized water 4 times, and finally disperse the PS precipitate in 50 mL of anhydrous ethanol to obtain a PS seed ethanol dispersion (concentration of 12.5 mg / mL).
[0038] 2) Take 25 mL of PS seed ethanol dispersion obtained in step 1), add 35 mL of anhydrous ethanol to dilute, and sonicate for 15 min (ultrasonic power of 300 W) to form a homogeneous suspension; add 0.15 mL of 3-aminopropyltriethoxysilane (APTES), and stir at 200 rpm for 5 h at room temperature; after the reaction, centrifuge at 8000 rpm for 9 min, and wash the centrifuged product with anhydrous ethanol 34 times to obtain aminated PS (PS-NH2) ethanol dispersion (concentration 6 mg / mL).
[0039] 3) Add 35 mL of PS-NH2 ethanol dispersion, 17 mL of anhydrous ethanol, and 6.5 mL of deionized water to a 100 mL three-necked flask. Add 0.7 mL of 26 wt% ammonia solution dropwise while stirring (180 rpm) to adjust the pH to 9. Then, add 0.45 mL of tetraethyl orthosilicate dropwise through a constant pressure dropping funnel. After the addition is complete, raise the temperature to 45 °C and keep the reaction at this temperature for 2.5 h. After the reaction is complete, centrifuge at 9000 rpm for 9 min. Wash the centrifuged product four times with anhydrous ethanol and then vacuum dry it (at a temperature of 40 °C for 8 h) to obtain dumbbell-shaped PS / SiO2 composite microspheres.
[0040] 4) Take 0.15g of dumbbell-shaped PS / SiO2 composite microspheres, disperse them in 45mL of anhydrous ethanol, and sonicate for 15min (ultrasonic power of 300W); add 0.10mL of dodecyltrimethoxysilane (DTMS) and 0.10mL of deionized water (to provide water for hydrolysis), and stir at 200rpm for 2.5h at room temperature; after the reaction, centrifuge at 8000rpm for 11min, wash the centrifuged product with anhydrous ethanol 4 times, and then vacuum dry (vacuum drying temperature of 40℃ for 6h) to obtain hydrophobically modified dumbbell-shaped PS / SiO2 particles (only the SiO2 exposed area is modified by DTMS, and the PS area does not react).
[0041] 5) Add 0.10 g of hydrophobically modified dumbbell-shaped PS / SiO2 to 7 mL of tetrahydrofuran (THF) and stir at 150 rpm for 5 h at room temperature (at which point the PS is completely dissolved); then centrifuge at 10000 rpm for 16 min, discard the upper PS / THF solution, wash the centrifuged product twice with THF, then wash twice with anhydrous ethanol, and then vacuum dry (vacuum drying temperature is 40℃, time is 6.5 h) to obtain hemispherical Janus-SiO2 particles (the upper hemisphere is a DTMS hydrophobic layer, and the bottom retains the SiO2 hydrophilic hydroxyl groups).
[0042] The process of using the hemispherical Janus-SiO2 particle additive obtained by the above method of the present invention to prepare emulsion is as follows: The hemispherical Janus-SiO2 particle additive for the emulsion was added to a mixed solution of 20 ml rapeseed oil and 20 ml water at a ratio of 3 wt%, and emulsified for 45 min at a speed of 7000 r / min using a homogenizer to obtain an emulsion containing the hemispherical Janus-SiO2 particle additive.
[0043] Example 3 The preparation process of the hemispherical Janus-SiO2 particle additive for emulsions in this embodiment is as follows: 1) Add 10 mL of styrene (St) that has been deionized by vacuum distillation to remove polymerization inhibitors and 150 mL of deionized water to a 250 mL three-necked flask, and purge with nitrogen (50 mL / min) to remove oxygen for 30 min; heat to 80 °C, and add 0.25 g of potassium persulfate (KPS) aqueous solution purified by recrystallization (dissolved in 5 mL of deionized water). After sealing the system, react with stirring at 250 rpm for 6-8 h; after the reaction is complete, cool to room temperature, centrifuge at 10000 rpm for 15 min, wash the centrifuged product with deionized water 5 times, and finally disperse the PS precipitate in 50 mL of anhydrous ethanol to obtain a PS seed ethanol dispersion (concentration of 15 mg / mL).
[0044] 2) Take 30 mL of PS seed ethanol dispersion obtained in step 1), add 40 mL of anhydrous ethanol to dilute, and sonicate for 15 min (ultrasonic power of 300 W) to form a homogeneous suspension; add 0.2 mL of 3-aminopropyltriethoxysilane (APTES), and stir at 200 rpm for 6 h at room temperature; after the reaction, centrifuge at 8000 rpm for 11 min, and wash the centrifuged product 4 times with anhydrous ethanol to obtain aminated PS (PS-NH2) ethanol dispersion (concentration 7 mg / mL).
[0045] 3) Add 40 mL of PS-NH2 ethanol dispersion, 20 mL of anhydrous ethanol, and 8 mL of deionized water to a 100 mL three-necked flask. Add 1 mL of 25 wt% ammonia solution dropwise while stirring (180 rpm) to adjust the pH to 8. Then, add 0.6 mL of tetraethyl orthosilicate dropwise through a constant pressure dropping funnel. After the addition is complete, raise the temperature to 55 °C and keep the reaction at this temperature for 3 h. After the reaction is complete, centrifuge at 9000 rpm for 9 min. Wash the centrifuged product 5 times with anhydrous ethanol and then vacuum dry it (at a temperature of 40 °C for 8 h) to obtain dumbbell-shaped PS / SiO2 composite microspheres.
[0046] 4) Take 0.2g of dumbbell-shaped PS / SiO2 composite microspheres, disperse them in 50mL of anhydrous ethanol, and sonicate for 15min (ultrasonic power of 300W); add 0.15mL of dodecyltrimethoxysilane (DTMS) and 15mL of deionized water (to provide water for hydrolysis), and stir at 200rpm for 3h at room temperature; after the reaction, centrifuge at 8000rpm for 9min, wash the centrifuged product 5 times with anhydrous ethanol, and then vacuum dry (vacuum drying temperature of 40℃ for 6h) to obtain hydrophobically modified dumbbell-shaped PS / SiO2 particles (only the SiO2 exposed area is modified by DTMS, and the PS area does not react).
[0047] 5) Add 0.15g of hydrophobically modified dumbbell-shaped PS / SiO2 to 10mL of tetrahydrofuran (THF) and stir at 150rpm for 6h at room temperature (at which point the PS is completely dissolved); then centrifuge at 10000rpm for 14min, discard the upper PS / THF solution, wash the centrifuged product with THF 3 times, then wash it with anhydrous ethanol once, and then vacuum dry it (vacuum drying temperature is 40℃, time is 5.5h) to obtain hemispherical Janus-SiO2 particles (the upper hemisphere is a DTMS hydrophobic layer, and the bottom retains the SiO2 hydrophilic hydroxyl groups).
[0048] The process of using the hemispherical Janus-SiO2 particle additive obtained by the above method of the present invention to prepare emulsion is as follows: The hemispherical Janus-SiO2 particle additive for the emulsion was added to a mixed solution of 25 ml rapeseed oil and 25 ml water at a ratio of 5 wt%, and emulsified for 60 min at a speed of 8000 r / min using a homogenizer to obtain an emulsion containing the hemispherical Janus-SiO2 particle additive.
[0049] The emulsions containing hemispherical Janus-SiO2 particles prepared in Examples 1-3 above were subjected to friction and wear tests. The tribological properties were evaluated using an MS-T3001 friction and wear testing machine. The fixed parameters were: load 10N, rotation speed 100r / min, and rotation diameter 5mm. The friction pairs were GCr15 bearing steel balls and a Zr-4 alloy disk. Before the experiment, the balls and disk were ultrasonically cleaned with petroleum ether and ethanol respectively to ensure a smooth surface. After the sample was mounted, a small amount of emulsion was dripped onto the Zr-4 alloy disk, and then the machine was started. After 30 minutes of testing, the test was stopped, and the relevant friction coefficient curves were recorded (e.g., ...). Figure 2 , Figure 3 (As shown).
[0050] The emulsions containing hemispherical Janus-SiO2 particles prepared in Examples 1-3 were subjected to a 30-day static stability test.
[0051] Comparative Example 1 This comparative example does not use any lubricant for friction and wear testing. An MS-T3001 friction and wear testing machine was used to evaluate tribological properties. Fixed parameters were: load 10N, rotation speed 100r / min, and rotation diameter 5mm. The friction pairs were GCr15 bearing steel balls and a Zr-4 alloy disc. Before the experiment, the balls and disc were ultrasonically cleaned with petroleum ether and ethanol respectively to ensure a smooth surface. After the sample was mounted, a small amount of emulsion was dripped onto the Zr-4 disc. The machine was started and rotated. After 30 minutes of testing, the test was stopped, and the relevant friction coefficient curves were recorded (e.g., ...). Figure 2 , Figure 3 (As shown).
[0052] Comparative Example 2 This comparative example uses an emulsion without any additives (i.e., 15 ml rapeseed oil and 15 ml water mixed and emulsified at 6000 r / min for 30 min using a homogenizer) for friction and wear testing. An MS-T3001 friction and wear testing machine was used to evaluate the tribological properties. Fixed parameters were: load 10 N, rotation speed 100 r / min, and rotation diameter 5 mm. The friction pairs were GCr15 bearing steel balls and a Zr-4 titanium alloy disc. Before the experiment, the balls and disc were ultrasonically cleaned with petroleum ether and ethanol respectively to ensure a smooth surface. After the sample was mounted, a small amount of emulsion was dripped onto the Zr-4 disc, and then the machine was started. After 30 min of testing, the test was stopped, and the relevant friction coefficient curves were recorded (e.g., ...). Figure 2 , Figure 3 (As shown).
[0053] Comparative Example 3 The emulsion without any additives (i.e., 15ml rapeseed oil and 15ml water mixed and emulsified in a homogenizer at 6000r / min for 30min) was subjected to a 30-day static stability test.
[0054] Comparative Example 4 The emulsion containing unmodified SiO2 particles was subjected to a 30-day static stability test. Specifically, in this comparative example, the additive (i.e., unmodified SiO2 particles) was added to a mixture of 15 ml rapeseed oil and 15 ml water at a ratio of 1 wt%, and emulsified for 30 min at 6000 r / min using a homogenizer to obtain the emulsion of this comparative example.
[0055] In the unlubricated dry friction and wear test of Zr-4 alloy disk, its friction coefficient was 0.440 (Comparative Example 1); after adding an emulsion without any additives to the test system, the friction coefficient dropped to 0.235 (Comparative Example 2), a reduction of 46.6% compared to the dry friction condition.
[0056] When an emulsion containing hemispherical Janus-SiO2 particles was used, the system's friction coefficient decreased significantly. The friction coefficients of Examples 1–3 were as low as 0.104, 0.098, and 0.095, respectively, representing a reduction of 76.4%–78.4% compared to dry friction conditions. Wear performance test results showed that the wear rates of Examples 1–3 were 7.95 × 10⁻⁶, respectively. -5 mm 3 / (N m), 7.58×10 -5 mm 3 / (N m) and 7.952×10 -5 mm 3 / (N Compared to dry friction conditions, the wear rate was reduced by as much as 88.4%–89.1% (see Figure 4).
[0057] The stability test results of the emulsion showed that: the emulsion without any additives showed obvious stratification after standing for 30 days, and the emulsion ratio was only 0.64 (Comparative Example 3); the emulsion with added unmodified SiO2 particles showed only a small amount of stratification after standing for 30 days, and the emulsion ratio increased to 0.82 (Comparative Example 4); while the emulsion with added hemispherical Janus-SiO2 particles (Examples 1–Examples 3) did not show any stratification after standing for 30 days, and the emulsion ratio was as high as 1 (see Figures 5 and 6).
[0058] The experimental results above show that, compared with traditional additives, this invention has the following characteristics: 1) The hemispherical Janus-SiO2 particle additive disperses more evenly and stably in rapeseed oil, exhibits better stability after standing, and shows no obvious stratification after standing for 45 days, demonstrating excellent stability.
[0059] 2) Due to their unique amphiphilicity, hemispherical Janus-SiO2 particles can be effectively adsorbed in the friction pair, thereby effectively reducing workpiece wear. Experiments have shown that the average friction coefficient can be reduced to 0.095~0.104, and the wear rate is significantly reduced by 88.4%-89.1%, which is significantly better than emulsions with conventional nanoparticles. 3) The emulsion containing hemispherical Janus-SiO2 particles prepared by this invention has both excellent friction reduction and wear reduction effects and emulsion stabilization ability, and can be widely used in the cold rolling process of difficult-to-machine metals. 4) The addition of hemispherical Janus-SiO2 particles is environmentally friendly and has a simple preparation process that requires no complex equipment, is inexpensive, and is easy to industrialize.
[0060] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.
[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.
Claims
1. A method for preparing hemispherical Janus-SiO2 particle additives for emulsions, characterized in that, The process includes the following: A composite microsphere is prepared by combining a first-phase microsphere with SiO2 particles; in the composite microsphere, the first-phase microsphere is connected to the SiO2 particles, with one end being the first-phase microsphere and the other end being the SiO2 particles, wherein the SiO2 particles are hydrophilic. The composite microspheres are hydrophobically modified to give the exposed surface of the SiO2 particles a hydrophobic layer; then the first phase microspheres are removed to expose the hydrophilic surface of the SiO2 particles, thus obtaining the hemispherical Janus-SiO2 particle additive for emulsions.
2. The method for preparing hemispherical Janus-SiO2 particle additives for emulsions according to claim 1, characterized in that, The first phase microspheres are polystyrene microspheres.
3. The method for preparing hemispherical Janus-SiO2 particle additives for emulsions according to claim 2, characterized in that, The preparation process of the composite microspheres includes: Styrene that has been deionized by vacuum distillation to remove the polymerization inhibitor and deionized water are added and mixed to obtain mixture A. Mixture A is heated to 70-80℃ under a protective atmosphere, and then potassium persulfate aqueous solution is added to react. After the reaction is completed, solid-liquid separation and washing are performed, and then the washing product is dispersed in anhydrous ethanol to obtain polystyrene seed ethanol dispersion. The polystyrene seed ethanol dispersion was homogenized to form a suspension. 3-aminopropyltriethoxysilane was added to the suspension for reaction, followed by solid-liquid separation and washing. The washing product was then dispersed in anhydrous ethanol to obtain an aminated PS (PS-NH2) ethanol dispersion. Anhydrous ethanol and deionized water were added to the aminated PS (PS-NH2) ethanol dispersion for dilution, and ammonia was added to adjust the pH to 8-9. Tetraethyl orthosilicate was then added, and the reaction was maintained at 35-55°C for 2-3 hours. After the reaction, solid-liquid separation, washing, and vacuum drying were performed to obtain the composite microspheres.
4. The method for preparing hemispherical Janus-SiO2 particle additives for emulsions according to claim 3, characterized in that: For every 8-10 mL of styrene, add 120-150 mL of deionized water and 5 mL of potassium persulfate aqueous solution, wherein the potassium persulfate aqueous solution contains 0.15-0.25 g of potassium persulfate, and the concentration of the polystyrene seed ethanol dispersion is 10-15 mg / mL; For every 20-30 mL of polystyrene seed ethanol dispersion, add 30-40 mL of anhydrous ethanol and 0.1-0.2 mL of 3-aminopropyltriethoxysilane; the concentration of the aminated PS (PS-NH2) ethanol dispersion is 5-7 mg / mL; for every 30-40 mL of the dispersion, add 15-20 mL of anhydrous ethanol, 5-8 mL of deionized water, 0.5-1 mL of 25-28 wt% ammonia, and 0.3-0.6 mL of tetraethyl orthosilicate.
5. The method for preparing hemispherical Janus-SiO2 particle additives for emulsions according to claim 3 or 4, characterized in that: The protective atmosphere is nitrogen; the potassium persulfate aqueous solution is added dropwise; after adding the potassium persulfate aqueous solution, the system is sealed and reacted at 245-255 rpm for 6-8 hours with stirring. After the reaction is completed, the mixture is cooled to room temperature and centrifuged at 99950-10050 rpm for 14-16 minutes. The centrifuged product is washed with deionized water 3-5 times to obtain the washed product. The polystyrene seed ethanol dispersion was homogenized by ultrasonication to form a suspension. The ultrasonic power was 290-310W, and the ultrasonication time was 14-16 min. 3-Aminopropyltriethoxysilane was added to the suspension for reaction. After solid-liquid separation and washing, the mixture was stirred at 195-205 rpm for 4-6 h, then centrifuged at 7950-8050 rpm for 9-11 min, and washed 3-5 times with anhydrous ethanol. Ammonia was added while stirring at 175-185 rpm. After the addition of tetraethyl orthosilicate, the mixture was centrifuged at 8950-9050 rpm for 9-11 min, and then washed 3-5 times with anhydrous ethanol. Vacuum drying was carried out at 38-42℃ for 7.5-8.5 h.
6. The method for preparing hemispherical Janus-SiO2 particle additives for emulsions according to claim 2, characterized in that, The process of hydrophobic modification of the composite microspheres includes: The composite microspheres were ultrasonically dispersed in anhydrous ethanol to obtain an ethanol dispersion of composite microspheres; wherein, 0.1-0.2 g of composite microspheres were added to every 40-50 mL of anhydrous ethanol, the ultrasonic power was 290-310 W, and the ultrasonic time was 14-16 min. Dodecyltrimethoxysilane and deionized water were added to the ethanol dispersion of the composite microspheres to carry out the reaction. After the reaction, the microspheres were separated, washed, and vacuum dried to obtain hydrophobically modified composite microspheres. For every 0.1-0.2 g of composite microspheres, 0.05-0.15 mL of dodecyltrimethoxysilane and 0.5-15 mL of deionized water were added, with the dodecyltrimethoxysilane added dropwise. The reaction was stirred at a rate of 195-205 rpm for 2-3 hours. Separation was performed by centrifugation at 7950-8050 rpm for 9-11 minutes. The microspheres were washed 3-5 times with anhydrous ethanol. Vacuum drying was carried out at 38-42℃ for 5.5-6.5 hours.
7. The method for preparing hemispherical Janus-SiO2 particle additives for emulsions according to claim 3, characterized in that, The process of removing the first-phase microspheres to expose the hydrophilic surface of the SiO2 particles includes: Hydrophobically modified composite microspheres were added to tetrahydrofuran until the polystyrene microspheres were completely dissolved; then solid-liquid separation and vacuum drying were performed to obtain the hemispherical Janus-SiO2 particle additive for emulsion. For every 5-10 mL of tetrahydrofuran, 0.05-0.15 g of hydrophobically modified composite microspheres were added. After adding the hydrophobically modified composite microspheres to tetrahydrofuran, the mixture was reacted at a stirring rate of 145-155 rpm for 4-6 h. Then, the mixture was centrifuged at a stirring speed of 9950-10050 rpm for 14-16 min, the supernatant was discarded, and the mixture was washed 2-3 times with tetrahydrofuran and then 1-2 times with anhydrous ethanol. The mixture was then vacuum dried at a temperature of 38-42℃ for 5.5-6.5 h.
8. A hemispherical Janus-SiO2 particle additive for emulsions prepared by any one of the preparation methods of claims 1-7.
9. The application of the hemispherical Janus-SiO2 particle additive for emulsions as described in claim 8, characterized in that, The hemispherical Janus-SiO2 particle additive is used to prepare emulsions.
10. The application according to claim 9, characterized in that, The process of preparing an emulsion includes: The hemispherical Janus-SiO2 particle additive for emulsion is added to a mixture of oil and water, and emulsified at a speed of 6000~8000 r / min for 30~60 min to obtain an emulsion containing hemispherical Janus-SiO2 particle additive. The amount of hemispherical Janus-SiO2 particle additive added is 1wt%~5wt% of the mass of the oil and water mixture; the volume ratio of oil to water in the oil and water mixture is (3~5):(3~5).