A method for modifying micro-nano oxide powder

Abstract

The application discloses a modification method of micro-nano oxide powder, and belongs to the technical field of powder material modification. The method comprises the following steps: adding the micro-nano oxide powder into a mixed solution of a hydrophobic modifier and water, uniformly stirring and mixing to form an oxide slurry; after curing the mixed oxide slurry at a certain temperature, separating and drying to obtain a hydrophobic modified micro-nano oxide powder; and adding the obtained hydrophobic modified micro-nano oxide powder into a mixed solution of a hydrophilic modifier and water to prepare a micro-nano oxide powder with internal hydrophobicity and external hydrophilicity. The micro-nano oxide powder is modified twice on the surface by adjusting the micro-nano oxide powder modifier and ratio, curing temperature and time, and selecting a drying mode, so that the micro-nano oxide powder with internal hydrophobicity and external hydrophilicity is obtained. The modification method is simple and efficient, and the modified micro-nano oxide powder has uniform particle size and outstanding modification effect.

Description

Technical Field

[0001] This invention relates to the field of powder material modification technology, specifically to a method for modifying micro / nano oxide powders. Background Technology

[0002] In recent years, micro and nano oxide powders have shown great application potential in composite materials, catalysis, electronics, biomedicine and coatings due to their unique size effect and surface properties.

[0003] Surface modification to impart new functions to these powders or improve their compatibility with the matrix is ​​a key technology for enhancing their added value and expanding their application range. Currently, surface modification methods for micro / nano oxide powders mainly include coupling agent modification, surface coating, and polymer grafting. Among these, silane coupling agents are widely used due to their ability to form strong chemical bonds with oxide surfaces. However, traditional liquid-phase modification processes often require large amounts of organic solvents (such as toluene and anhydrous ethanol), which is not only costly and environmentally polluting, but also presents challenges such as difficult solvent recovery and safety hazards.

[0004] Zhang et al. modified nano-zinc oxide using silane coupling agents in toluene solvent. While this effectively improved its dispersibility in polymers, the process involved large solvent volumes, required multiple washings after modification, was cumbersome, and prone to secondary agglomeration. Li et al., to achieve specific multifunctionality, often required composite modification of powders or the introduction of multiple functional groups. They used a stepwise method to modify silica with two silane coupling agents of different properties sequentially, aiming to simultaneously obtain hydrophobicity and reactivity. However, due to differences in the hydrolysis rate and surface hydroxyl reactivity of different coupling agents, this stepwise treatment easily led to uneven modified layers, unsatisfactory functional group coverage, and even self-condensation, making it difficult to achieve controllable composite modification effects. Wang's team attempted to use spray drying to rapidly dry silane-modified SiO2. While this reduced agglomeration to some extent, it failed to fundamentally solve the particle aggregation caused by capillary forces in the early stages of modification due to the presence of solvent. Furthermore, this method required sophisticated equipment and consumed significant energy.

[0005] Therefore, developing a new method that is green and efficient, applicable to multi-component systems, and enables uniform and controllable composite surface modification is of vital importance for promoting the application of high-end micro- and nano-oxide powder materials. Summary of the Invention

[0006] To address the shortcomings of the prior art, this invention provides a method for modifying micro / nano oxide powders, employing an efficient and green process, simplifying preparation steps, adapting to industrial production, and reducing production costs; and using a controllable composite surface modification method to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for modifying micro / nano oxide powders includes the following steps:

[0009] Step 1: Mix the hydrophobic modifier with water in a certain proportion to obtain a hydrophobic modified mixed solution. Then, mix the micro / nano oxide powder with the hydrophobic modified mixed solution in a certain proportion to prepare an oxide mixed slurry.

[0010] Step 2: After thoroughly mixing the oxide mixture, seal and cure it at a certain temperature;

[0011] Step 3: After solid-liquid separation of the cured slurry, the solid product is frozen and then dried at a certain temperature to obtain hydrophobic modified oxide powder.

[0012] Step 4: Mix the hydrophilic modifier with water in a certain proportion and stir to obtain a hydrophilic modified mixed solution;

[0013] Step 5: Mix the hydrophobic modified oxide powder into the hydrophilic modified mixed solution from Step 4, and continue stirring and mixing under certain temperature conditions;

[0014] Step 6: After separating the solid and liquid components of the mixed slurry, the solid product is dried to obtain micro-nano oxide powder with an inner hydrophobic and outer hydrophilic structure.

[0015] Furthermore, the hydrophobic modifier is selected from any one or more of hexamethyldisilazane (HMDS), polymethylhydrosiloxane (PMHS), sodium dodecylbenzenesulfonate (SDBS), oleic acid (OA), stearic acid (SA), hexadecyltrimethylammonium bromide (CTAB), dioctadecyldimethylammonium chloride (DODMAC), γ-glycidyl etheroxypropyltrimethoxysilane (KH-560), Span 80, and tetraethyl orthosilicate (TEOS); the hydrophilic modifier is selected from any one or more of citric acid (CA), polyacrylic acid (PAA), polyethylene glycol (PEG), polyethylene oxide (PEO), benzalkonium chloride (BAC), and Tween 80.

[0016] Furthermore, the micro / nano oxide powder in step 1 includes any one of the micro / nano powders of various metal oxides and silicon oxide.

[0017] Furthermore, in step 1, the particle size of the micro / nano oxide powder is <100μm; the proportion of the hydrophobic modifier in the mixed solution is 0.001% to 30wt%; and the solid content of the oxide mixed slurry is 0.1% to 100wt%.

[0018] Furthermore, the curing temperature is 20–150℃, and the curing time is 0.5–48 hours.

[0019] Furthermore, in step 3, the freezing temperature is -40℃ and the freezing time is 5-8 hours.

[0020] Furthermore, in steps 3 and 6, the drying temperature is -40 to 60°C, the drying time is 0.5 to 48 hours, and the drying method includes one of drying using a high-temperature oven, drying using a vacuum dryer, or drying using a freeze dryer.

[0021] Furthermore, in step 4, the proportion of the hydrophilic modifier in the mixed solution is 0.001% to 30 wt%.

[0022] Furthermore, in step 5, the solid content of the hydrophobic oxide mixed slurry is 0.1% to 100 wt%.

[0023] Furthermore, in step 5, magnetic stirring is used, with a stirring speed of 500–2000 rpm, a heating temperature of 30–60°C, and a stirring time of 0.5–48 h.

[0024] The present invention has the following beneficial effects:

[0025] 1) By employing a unique surface modification process and optimizing the addition method of the modifier and the stirring kinetics during the reaction process, the modifier is ensured to achieve a dense and uniform monolayer coating on the surface of micro-nano oxide powder, thereby significantly improving the dispersion stability and compatibility of the modified micro-nano powder.

[0026] 2) Compared with existing technologies, chemical methods such as wet chemical methods often require the use of expensive surface modifiers and are carried out under harsh conditions such as high temperature and inert gas protection, resulting in high preparation costs, complex processes and safety hazards. This invention shortens the process flow and greatly improves the safety of production operations by selecting low-cost and universal modifiers and carrying out single-step modification under mild conditions of room temperature and pressure. Attached Figure Description

[0027] Figure 1 The following are actual photographs of the samples: (a) ZnO@SA powder, (b) CaO@OA powder, (c) CeO2@Span powder, (d) Al2O3@Tween powder, (e) TiO2@TEOS powder, (f) CeO2@PAA powder, and (g) a photograph of the sample in Comparative Example 1.

[0028] Figure 2The following are contact angle test results for modified powders: (a) ZnO@SA powder contact angle, (b) CaO@OA powder contact angle, (c) CeO2@Span powder contact angle, (d) Al2O3@Tween powder contact angle, (e) TiO2@TEOS powder contact angle, (f) CeO2@PAA powder contact angle, (g) ZrO2@PAA powder contact angle, (h) CeO2@CTAB powder contact angle, and (i) CeO2@Tween powder contact angle in Comparative Example 3.

[0029] Figure 3 The following graphs show the changes in suspension rate over time: (a) CeO2@PAA powder suspension rate over time; (b) ZrO2@PAA powder suspension rate over time; (c) CeO2@PMHs@Tween powder suspension rate over time; (d) TiO2@TEOS@KH-560 powder suspension rate over time; (e) CeO2@Span@Tween powder suspension rate over time; (f) Fe3O4@TEOS@PEG powder suspension rate over time; (g) Suspension rate of sample in Comparative Example 2 over time; (h) Suspension rate of sample in Comparative Example 3 over time; (i) Suspension rate of sample in Comparative Example 4 over time; (j) Suspension rate of sample in Comparative Example 5 over time.

[0030] Figure 4 The figures show the contact angle test results after two modifications: (a, a1) contact angle changes of CeO2@PMHs@Tween powder after one and two modifications; (b, b1) contact angle changes of TiO2@TEOS@KH-560 powder after one and two modifications; (c, c1) contact angle changes of CeO2@Span@Tween powder after one and two modifications; (d, d1) contact angle changes of Fe3O4@TEOS@PEG powder after one and two modifications; and (e, e1) contact angle changes of CeO2@Tween@PMHs powder after one and two modifications in Comparative Example 4. Detailed Implementation

[0031] The technical solution of the present invention will now be clearly and completely described in conjunction with the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1

[0033] (1) Weigh 1.58g of stearic acid and 68.42g of water, place them in a 100ml glass beaker, and stir magnetically for 2 hours at 600rpm to obtain a mixed solution;

[0034] (2) Add 20g of nano zinc oxide powder to a beaker, continue stirring for 2 hours, and then place it in an oven at 80℃ for 1 hour to cure in a sealed environment.

[0035] (3) Take out the sample and let it stand to cool. Then, centrifuge and wash it 4 times at 1000r in a high-speed centrifuge. Then freeze it at -40℃ for 8 hours.

[0036] (4) The powder was vacuum dried at 60°C for 24 hours in a vacuum drying oven to obtain SA-modified nano zinc oxide (ZnO@SA) powder.

[0037] The ZnO@SA powder obtained in Example 1 was tested, and the actual photograph of the obtained ZnO@SA powder is shown below. Figure 1 As shown in (a), the contact angle of the obtained ZnO@SA powder is as follows: Figure 2 As shown in (a), the modification of zinc oxide with fatty acids is successful. Through effective modification of fatty acids, its transparency and dispersibility in sunscreen can be improved, and its compatibility with rubber can be enhanced.

[0038] Example 2

[0039] (1) Weigh 3.5g of oleic acid and 54.92g of water, place them in a 100ml glass beaker, and stir magnetically for 2 hours at 600rpm to obtain a mixed solution;

[0040] (2) Add 15g of nano calcium oxide powder to a beaker, continue stirring for 2 hours, and then place it in an oven at 60℃ for 3 hours of sealed curing.

[0041] (3) Take out the sample and let it stand to cool. Then, centrifuge and wash it 4 times at 1000r in a high-speed centrifuge, and then freeze it at -40℃ for 5h.

[0042] (4) Then, the powder was vacuum dried at 60°C for 24 hours in a vacuum drying oven to obtain OA modified nano calcium oxide (CaO@OA) powder.

[0043] The CaO@OA powder obtained in Example 2 was tested, and the actual photos are shown below. Figure 1 As shown in (b), the contact angle is as follows Figure 2 As shown in (b), the obtained CaO@OA powder is modified with oleic acid onto calcium oxide, which effectively prevents it from reacting with water and CO2 in the air and thus extends its shelf life.

[0044] Example 3

[0045] (1) Weigh 4g of Span 80 and 55g of water, place them in a 100ml glass beaker, and stir magnetically at 600rpm for 5h to obtain a mixed solution;

[0046] (2) Then add 30g of nano-cerium oxide powder to the beaker, continue stirring for 2 hours, and then place it in an oven at 60℃ for 1 hour to cure in a sealed environment.

[0047] (3) Take out the sample and let it stand to cool. Then, centrifuge and wash it 4 times at 1000r in a high-speed centrifuge. Then freeze it at -40℃ for 8 hours.

[0048] (4) Then, vacuum drying was carried out in a freeze dryer at -40℃ for 24h to obtain Span 80 modified nano cerium oxide (CeO2@Span) powder;

[0049] The CeO2@Span powder obtained in Example 3 was tested, and the actual photos are shown below. Figure 1 As shown in (c), the contact angle is as follows: Figure 2 As shown in (c), the contact angle of the modified cerium oxide is 159.218°, which indicates that Span successfully modified the cerium oxide surface and changed its surface properties.

[0050] Example 4

[0051] (1) Weigh 4g of Tween 80 and 30g of water, place them in a 100ml glass beaker, and stir magnetically at 600rpm for 2h to obtain a mixed solution;

[0052] (2) Add 6g of nano alumina powder to a beaker, continue stirring for 2 hours, and then place it in an oven at 40℃ for 6 hours of sealed curing.

[0053] (3) Take out the sample and let it stand to cool. Then, centrifuge and wash it 4 times at 1000r in a high-speed centrifuge. Then freeze it at -40℃ for 8 hours.

[0054] (4) Then, the powder was vacuum dried at -20℃ for 24h in a freeze dryer to obtain Tween80 modified nano alumina (Al2O3@Tween) powder.

[0055] The Al2O3@Tween powder obtained in Example 4 was tested, and the actual photos are shown below. Figure 1 As shown in (d), the contact angle is as follows Figure 2 As shown in (d), Tween long-chain molecules are adsorbed onto the surface of alumina particles through hydrogen bonds and van der Waals forces. Their polyoxyethylene chains provide a strong steric hindrance effect, which significantly prolongs the stabilization time of the alumina polishing slurry.

[0056] Example 5

[0057] (1) Weigh 4g of tetraethyl orthosilicate and 10g of water, place them in a 100ml glass beaker, and stir magnetically for 2 hours at 600rpm to obtain a mixed solution;

[0058] (2) Add 15g of nano titanium dioxide powder to a beaker, stir for 30min, add an additional 40g of water, continue stirring for 2h, and then place it in an oven at 40℃ for 30min to cure in a sealed environment.

[0059] (3) Take out the sample and let it stand to cool. Then, centrifuge and wash it 4 times at 1000r in a high-speed centrifuge. Then freeze it at -40℃ for 8 hours.

[0060] (4) Then, the powder was vacuum dried at -40℃ for 24h in a freeze dryer to obtain TEOS modified nano titanium dioxide (TiO2@TEOS) powder.

[0061] The TiO2@TEOS powder obtained in Example 5 was tested, and the actual photos are shown below. Figure 1 As shown in (e), the contact angle is as follows Figure 2 As shown in (e), the contact angle indicates successful modification; TEOS was successfully modified onto the titanium oxide surface. Figure 2 As shown in (e), it is demonstrated that tetraethyl orthosilicate coating a layer of amorphous silica on the TiO2 surface inhibits the photocatalytic activity of TiO2 in the organic resin coating, preventing it from decomposing the surrounding organic resin under light and avoiding coating powdering and yellowing.

[0062] Example 6

[0063] (1) Weigh 4g of polyacrylic acid and 10g of water, place them in a 100ml glass beaker, and stir magnetically for 2 hours at 800rpm to obtain a mixed solution;

[0064] (2) Add 15g of nano-cerium oxide powder to a beaker, stir for 30min, add an additional 40g of water, continue stirring for 2h, and then place it in an oven at 100℃ for 8h of sealed curing.

[0065] (3) Take out the sample and let it stand to cool. Then, centrifuge and wash it 4 times at 1000r in a high-speed centrifuge. Then freeze it at -40℃ for 8 hours.

[0066] (4) Then, the powder was vacuum dried at -40℃ for 24h in a freeze dryer to obtain PAA-modified nano cerium oxide (CeO2@PAA) powder.

[0067] The CeO2@PAA powder obtained in Example 6 was tested, and the actual photos are shown below. Figure 1 As shown in (f), the contact angle is as follows: Figure 2 As shown in (f), its suspension rate changes with time as follows: Figure 3As shown in (a), the contact angle and good suspension and dispersion properties indicate that the modification was successful.

[0068] Example 7

[0069] (1) Weigh 4g of polyacrylic acid and 10g of water, place them in a 100ml glass beaker, and stir magnetically at 600rpm for 2h to obtain a mixed solution;

[0070] (2) Then add 15g of nano-zirconia powder, stir for 30min, add an additional 40g of water, continue stirring for 2h, and place in an oven at 85℃ for 4h of sealed curing.

[0071] (3) Take out the sample and let it stand to cool. Then, centrifuge and wash it 4 times at 1000r in a high-speed centrifuge. Then freeze it at -40℃ for 8 hours.

[0072] (4) Then, it was vacuum dried in a vacuum drying oven at 40°C for 24 hours to obtain PAA-modified nano-zirconia (ZrO2). 2@ PAA) powder.

[0073] The ZrO2@PAA powder obtained in Example 7 was tested, and the contact angle was as follows: Figure 2 As shown in (g), the change in suspension rate over time is as follows: Figure 3 As shown in (b), PAA was successfully modified onto ZrO2. The dissociated carboxyl anions from the PAA chains are adsorbed onto the particle surface via electrostatic attraction. The long-chain molecules of PAA form polymer brushes on the particle surface, generating strong steric hindrance. This excellent dispersibility allows for the addition of more ceramic powder while maintaining a fluid state, thereby reducing sintering shrinkage and deformation, and improving the density and strength of the finished product. A well-prepared slurry results in uniform particle packing with few defects after molding, leading to a uniform ceramic microstructure and excellent mechanical properties after sintering.

[0074] Example 8

[0075] (1) Weigh 4g of hexadecyltrimethylammonium bromide and 45g of H2O with a pH of 9, place them in a 100ml glass beaker, and stir magnetically at 600rpm for 2h to obtain a mixed solution;

[0076] (2) Then add 15g of nano cerium oxide powder, stir for 30min, add an additional 40g of water, continue stirring for 2h, and place in an oven at 85℃ for sealed curing for 4h.

[0077] (3) Take out the sample and let it stand to cool. Then, centrifuge and wash it 4 times at 1000r in a high-speed centrifuge. Then freeze it at -40℃ for 8 hours.

[0078] (4) The CTAB-modified nano-cerium oxide (CeO2@CTAB) powder was obtained by vacuum drying at -40℃ for 24h in a freeze dryer.

[0079] The CeO2@CTAB powder obtained in Example 8 was tested, and its contact angle was as follows: Figure 2 As shown in (h), CTAB was successfully modified onto the cerium oxide surface, enabling it to maintain good dispersibility in the emulsion.

[0080] Example 9

[0081] (1) Weigh 4g of polymethylhydrosiloxane and 40g of water, place them in a 100ml glass beaker, and stir magnetically at 600rpm for 2h to obtain a mixed solution; add 6g of nano-cerium oxide powder, continue stirring for 5h, and then place it in an oven at 60℃ for 4h of sealed curing.

[0082] (2) The sample was removed and allowed to cool, then centrifuged four times at 1000 rpm in a high-speed centrifuge, frozen at -40℃ for 8 hours, and vacuum dried at -40℃ for 24 hours in a freeze dryer to obtain PMHs hydrophobically modified nano-cerium oxide (CeO). 2@ PMHs) powder;

[0083] (3) Weigh 1g of Tween 80 and 20g of water, place them in a 100ml glass beaker, and stir magnetically for 30min at 60℃ and 100rpm to obtain a Tween mixed solution.

[0084] (4) Weigh 5g of PMHs hydrophobically modified nano cerium oxide (CeO2@PMHs) powder and slowly add it to the Tween mixed solution that is being stirred, and continue stirring for 1h.

[0085] (5) The mixed slurry was ultrasonicated in an ultrasonic machine for 8 hours, then centrifuged and washed 4 times at 1000 r in a high-speed centrifuge, and then vacuum dried at -40℃ for 24 hours in a freeze dryer.

[0086] (6) Take out the dried sample, put it into a ball mill, and ball mill it at 500 rpm for 7 hours. Take out the sample to obtain PMHs hydrophobic modified Tween 80 hydrophilic modified nano cerium oxide (CeO2@PMHs@Tween) powder.

[0087] The CeO2@PMHs@Tween powder obtained in Example 9 was tested, and the obtained CeO2@PMHs@ The change in Tween powder suspension rate over time is as follows: Figure 3 As shown in (c), the contact angle is as follows: Figure 4As shown in (a, a1), the suspension and dispersion performance of the modified cerium oxide is significantly improved. This is attributed to the fact that the two modifications enhanced the steric hindrance effect of cerium oxide in the polishing solution, thereby improving its suspension and dispersion performance. Figure 4 As shown in (a, a1), the sample successfully changed from hydrophobic to hydrophilic, and the contact angle of cerium oxide changed from hydrophobic to hydrophilic. This improved the steric hindrance effect and significantly enhanced its dispersion and suspension properties.

[0088] Example 10

[0089] (1) Weigh 4g of tetraethyl orthosilicate and 10g of water, place them in a 100ml glass beaker, and stir magnetically at 600rpm for 2h to obtain a mixed solution; add 15g of nano titanium dioxide powder, stir for 30min, add an additional 40g of water, continue stirring for 2h, and place in an oven at 60℃ for 4h of sealed curing.

[0090] (2) The sample was removed and allowed to cool. Then, it was centrifuged four times at 1000 rpm in a high-speed centrifuge. After that, it was frozen at -40℃ for 8 hours and then vacuum dried at -40℃ for 24 hours in a freeze dryer to obtain TEOS hydrophobically modified nano titanium dioxide (TiO2). 2@ TEOS) powder;

[0091] (3) Weigh 1g of γ-glycidyl oxypropyltrimethoxysilane and 20g of water, place them in a 100ml glass beaker, and stir magnetically for 30min at 60℃ and 100rpm to obtain KH-560 mixed solution.

[0092] (4) Weigh 5g of TEOS hydrophobically modified nano titanium dioxide (TiO2@TEOS) powder and slowly add it to the KH-560 mixed solution that is being stirred, and continue stirring for 1h;

[0093] (5) The mixed slurry was ultrasonicated in an ultrasonic machine for 8 hours, then centrifuged and washed 4 times at 1000 r in a high-speed centrifuge, and then vacuum dried at -40℃ for 24 hours in a freeze dryer.

[0094] (6) Take out the dried sample, put it into a ball mill, and ball mill it at 500 rpm for 7 hours. Take out the sample to obtain TEOS hydrophobic modified KH-560 hydrophilic modified nano titanium dioxide (TiO2@TEOS@KH-560) powder.

[0095] The TiO2@TEOS@KH-560 powder obtained in Example 10 was tested, and the change in the suspension rate of the TiO2@TEOS@KH-560 powder over time is shown below. Figure 3 As shown in (d), the contact angle of TiO2@TEOS@KH-560 powder is as follows: Figure 4 As shown in (b, b1), tetraethyl orthosilicate coats the TiO2 surface with an amorphous layer of silica, inhibiting the photocatalytic activity of TiO2 and preventing it from decomposing the surrounding organic resin under light, thus avoiding coating chalking and yellowing. Meanwhile, the SiO2 layer surface has abundant Si-OH groups, and the long-chain molecules of KH-560 form strong chemical bonds with the surface's robust hydroxyl groups. Figure 4 As shown in (b, b1), the transformation from hydrophobic after the first modification to hydrophilic after the second modification demonstrates that the two modifications successfully constructed TiO2 nanoparticles with an inner hydrophobic and an outer hydrophilic structure, which not only ensured the durability of the nano-TiO2 but also achieved its excellent dispersibility and strong interfacial bonding in the organic system.

[0096] Example 11

[0097] (1) Weigh 4g of Span 80 and 60g of water, place them in a 100ml glass beaker, and stir magnetically at 600rpm for 2h to obtain a mixed solution; add 6g of nano cerium oxide powder, continue stirring for 5h, and then place it in an oven at 60℃ for 4h of sealed curing.

[0098] (2) Take out the sample and let it stand and cool. Then, centrifuge and wash it 4 times at 1000r in a high-speed centrifuge, freeze it at -40℃ for 8h, and vacuum dry it at -40℃ for 24h in a freeze dryer to obtain Span80 hydrophobic modified nano cerium oxide (CeO2@Span) powder.

[0099] (3) Weigh 1g of Tween 80 and 20g of water, place them in a 100ml glass beaker, and stir magnetically for 30min at 60℃ and 100rpm to obtain a Tween mixed solution.

[0100] (4) Weigh 5g of PMHs hydrophobically modified nano cerium oxide (CeO2@PMHs) powder and slowly add it to the Tween mixed solution that is being stirred, and continue stirring for 1h.

[0101] (5) The mixed slurry was ultrasonicated in an ultrasonic machine for 8 hours, then centrifuged and washed 4 times at 1000 r in a high-speed centrifuge, and then vacuum dried in a vacuum drying oven at 60°C for 24 hours.

[0102] (6) Take out the dried sample, put it into a ball mill, and ball mill it at 500 rpm for 7 hours. Take out the sample to obtain Span80 hydrophobic modified Tween 80 hydrophilic modified nano cerium oxide (CeO2@Span@Tween) powder.

[0103] The CeO2@Span@Tween powder obtained in Example 11 was tested, and the change in the suspension rate of the CeO2@Span@Tween powder over time is shown below. Figure 3As shown in (e), the contact angle is as follows Figure 4 As shown in (c, c1), the two modifications successfully improved the dispersion and suspension performance of cerium oxide.

[0104] Example 12

[0105] (1) Weigh 4g of tetraethyl orthosilicate and 12g of water, place them in a 100ml glass beaker, and stir magnetically at 600rpm for 2h to obtain a mixed solution; add 13g of magnetic iron oxide nanoparticles, stir for 10min, add an additional 50g of water, continue stirring for 2h, and place in an oven at 60℃ for 6h of sealed curing.

[0106] (2) Take out the sample and let it stand and cool. Then, centrifuge and wash it 4 times at 1000r in a high-speed centrifuge. Then freeze it at -40℃ for 8h and vacuum dry it at 60℃ for 24h in a vacuum drying oven to obtain TEOS hydrophobic modified nano iron tetroxide (Fe3O4@TEOS) particles.

[0107] (3) Weigh 1g of polyethylene glycol and 6g of water, place them in a 100ml glass beaker, and stir magnetically for 30min at 60℃ and 100rpm to obtain a polyethylene glycol mixed solution.

[0108] (4) Weigh 5g of TEOS hydrophobically modified nano iron tetroxide (Fe3O4@TEOS) particles and slowly add them to the polyethylene glycol mixed solution that is being stirred, and continue stirring for 1h;

[0109] (5) The mixed slurry was centrifuged and washed 4 times in a high-speed centrifuge at a speed of 1000r, and then vacuum dried at -40℃ for 24h in a freeze dryer.

[0110] (6) Take out the dried sample, put it into a ball mill, and ball mill it at 500 rpm for 7 hours. Take out the sample to obtain TEOS hydrophobically modified PEG hydrophilic modified nano iron tetroxide (Fe3O4@TEOS). @PEG) powder.

[0111] Precipitation tests were performed on the Fe3O4@TEOS@PEG powder obtained in Example 12. The change in suspension rate of the Fe3O4@TEOS@PEG powder over time is shown below. Figure 3 (f), contact angle as Figure 4 As shown in (d, d1). Figure 4 (d, d1) proves that TEOS has been successfully modified into Fe3O4. Silica coating improves chemical stability and prevents magnetic Fe3O4 from being oxidized or dissolved in the physiological environment. Grafting polyethylene glycol and PEG improves biocompatibility, preventing rapid clearance by the human immune system and prolonging blood circulation time.

[0112] Comparative Example 1

[0113] (1) Weigh 4g of polyacrylic acid and 10g of water, place them in a 100ml glass beaker, and stir magnetically for 2 hours at 800rpm to obtain a mixed solution;

[0114] (2) Add 15g of nano-cerium oxide powder to a beaker, stir for 30min, add an additional 40g of water, continue stirring for 2h, and then place it in an oven at 100℃ for 8h of sealed curing.

[0115] (3) Take out the sample and let it stand to cool. Then, centrifuge and wash it 4 times at 1000r in a high-speed centrifuge. Then freeze it at -40℃ for 8 hours.

[0116] (4) Then, the powder was dried in an oven at 80°C for 6 hours to obtain PAA-modified nano-cerium oxide (CeO2@PAA) powder;

[0117] In Comparative Example 1, the samples were dried using a high-temperature oven. Figure 1 As shown in (g), a large number of cracked blocks were formed in the dried sample, indicating that the modified cerium oxide produced a large number of hard agglomerates that were difficult to separate, proving that improper drying methods led to the formation of hard agglomerates in the powder.

[0118] Comparative Example 2

[0119] (1) Weigh 4g of polymethylhydrosiloxane and 40g of water, place them in a 100ml glass beaker, and stir magnetically for 2 hours at 600rpm to obtain a mixed solution.

[0120] (2) Add 6g of nano-cerium oxide powder to a beaker, continue stirring for 5h, and then place it in an oven at 60℃ for 4h in a sealed environment.

[0121] (3) Take out the sample and let it stand and cool. Then, centrifuge and wash it 4 times at 1000r in a high-speed centrifuge and freeze it at -40℃ for 8h.

[0122] (4) Then, the powder was vacuum dried at -40℃ for 24h in a freeze dryer to obtain PMHs modified nano cerium oxide (CeO2@PMHs) powder.

[0123] Compared to Example 9, Comparative Example 2 only underwent one modification using PMHs. Figure 3(g) is a graph showing the change in suspension rate over time. The suspension performance of the PMHs-modified nano-cerium oxide (CeO2@PMHs) powder was greatly reduced because it did not undergo secondary hydrophilic modification. The agglomeration caused by hydrophobicity actually reduced the suspension performance of the modified cerium oxide. The secondary modification greatly reduced the agglomeration tendency of cerium oxide. While possessing the double-layer steric hindrance effect, it also has dispersion performance, proving that the main reason for the precipitation of the sample is the direct agglomeration tendency of the particles.

[0124] Comparative Example 3

[0125] (1) Weigh 1g of Tween 80 and 20g of water, place them in a 100ml glass beaker, and stir magnetically for 2 hours at 600rpm to obtain a mixed solution;

[0126] (2) Add 5g of nano cerium oxide powder, continue stirring for 5h, and then place it in an oven at 60℃ for 4h for sealed curing;

[0127] (3) Take out the sample and let it stand and cool. Then, centrifuge and wash it 4 times at 1000r in a high-speed centrifuge and freeze it at -40℃ for 8h.

[0128] (4) The Tween 80 hydrophobically modified nano-cerium oxide (CeO) was obtained by vacuum drying at -40℃ for 24 h in a freeze dryer. 2@ Tween) powder.

[0129] Compared to Example 9, Comparative Example 3 only underwent one modification with Tween 80. Figure 2 (i) is the contact angle test. Figure 3 (h) represents the obtained CeO2@ The change in the suspension rate of Tween powder over time indicates that modification with only Tween 80 is a hydrophilic modification. Figure 2 (i) The modified powder exhibits hydrophilicity. Figure 3 (h) and Figure 3 (c) A comparison reveals that CeO2@ The suspension rate of Tween powder was significantly lower than that of CeO2@PMHs@Tween. This is because Tween 80 modification alone can only change the properties of the cerium oxide surface and cannot enhance its steric hindrance effect. Therefore, its performance is significantly reduced compared to Example 9.

[0130] Comparative Example 4

[0131] (1) Weigh 2g of Tween 80 and 40g of water, place them in a 100ml glass beaker, and stir magnetically at 600rpm for 2h to obtain a mixed solution; add 10g of nano cerium oxide powder, continue stirring for 5h, and then place it in an oven at 60℃ for 4h of sealed curing.

[0132] (2) The sample was removed and allowed to cool, then centrifuged four times at 1000 rpm in a high-speed centrifuge, frozen at -40℃ for 8 hours, and vacuum dried at -40℃ for 24 hours in a freeze dryer to obtain Tween 80 hydrophobically modified nano-cerium oxide (CeO). 2@ Tween) powder;

[0133] (3) Weigh 4g of polymethylhydrosiloxane and 40g of water, place them in a 100ml glass beaker, and stir magnetically for 30min at 60℃ and 100rpm to obtain a Tween mixed solution.

[0134] (4) Weigh 6g of Tween 80 hydrophobically modified nano cerium oxide (CeO2@Tween) powder and slowly add it to the Tween mixed solution that is being stirred, and continue stirring for 1h;

[0135] (5) The mixed slurry was ultrasonicated in an ultrasonic machine for 8 hours, then centrifuged and washed 4 times at 1000 r in a high-speed centrifuge, and then vacuum dried at -40℃ for 24 hours in a freeze dryer.

[0136] (6) Take out the dried sample, put it into a ball mill, and ball mill it at 500 rpm for 7 hours. Take out the sample to obtain modified nano cerium oxide (CeO2@Tween @PMHs) powder.

[0137] Compared to Example 9, Comparative Example 4 used a modification method of first applying Tween 80 and then PMHs. Figure 3 (i) is the obtained CeO2@ Changes in Tween powder suspension rate over time Figure 4 (e, e1) represents the contact angle test, which uses a method of first applying Tween 80 followed by PMHs. This results in the CeO2@Tween @PMHs powder exhibiting initially hydrophilic properties followed by hydrophobic properties. Figure 3 As shown in (i), this causes the powder to agglomerate in large quantities due to the hydrophobic effect, and the performance decreases significantly after agglomeration.

[0138] Comparative Example 5

[0139] (1) Weigh 4g of polymethylhydrosiloxane, 2g of Tween and 40g of water, place them in a 100ml glass beaker, and stir magnetically for 2h at 600rpm to obtain a mixed solution.

[0140] (2) Add 6g of nano cerium oxide powder, continue stirring for 5h, and then place it in an oven at 60℃ for 4h of sealed curing;

[0141] (3) Take out the sample and let it stand and cool. Then, centrifuge and wash it 4 times at 1000r in a high-speed centrifuge and freeze it at -40℃ for 8h.

[0142] (4) The nano-cerium oxide (CeO) was obtained by vacuum drying at -40℃ for 24 hours in a freeze dryer. 2@ PMHs&Tween) powder.

[0143] Compared to Example 9, Comparative Example 5 used a method of simultaneous modification with Tween 80 and PMHs. Figure 3 (j) represents the obtained CeO2@ The change in Tween powder suspension rate over time, CeO 2@ The PMHs&Tween powder did not exhibit a hydrophobic effect when placed in water, and the powder was basically completely precipitated within a day. The reason for this phenomenon may be that the mixing of the two modifiers caused the cerium oxide surface to form a chaotic structure with various molecular chains cross-linked, resulting in a large amount of cerium oxide agglomeration. Therefore, the surface modification of the powder failed and the performance was significantly reduced.

[0144] In summary, this invention addresses the problem of oxide modification by developing a method for modifying micro / nano oxide powders. The method involves adding micro / nano oxide powders to a mixed solution of one or more modifiers and deionized water, followed by uniform stirring to form an oxide slurry. The mixed oxide slurry is then cured in an oven. Finally, the mixed oxide slurry is subjected to static settling and freeze-drying to obtain the modified micro / nano oxide powders. This simple physical blending and freeze-drying method results in a short production cycle, high industrialization rate, and high production safety. The modified micro / nano oxide powders produced by this method exhibit diverse functions, significant effects, low preparation cost, long shelf life, and low storage cost.

[0145] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be defined by the claims.

Claims

1. A method for modifying micro / nano oxide powders, characterized in that, Includes the following steps: Step 1: Mix the hydrophobic modifier with water to obtain a hydrophobic modified mixed solution, and then prepare an oxide mixed slurry by mixing the micro / nano oxide powder with the hydrophobic modified mixed solution. Step 2: After thoroughly mixing the oxide mixture, seal and cure it. Step 3: After solid-liquid separation of the cured slurry, the solid product is frozen and then dried to obtain hydrophobic modified oxide powder; Step 4: Mix the hydrophilic modifier with water and stir until well mixed to obtain a hydrophilic modified mixed solution; Step 5: Add the hydrophobic modified oxide powder to the hydrophilic modified mixed solution in Step 4 and stir to mix, so as to obtain the hydrophobic oxide mixed slurry. Step 6: After solid-liquid separation of the hydrophobic oxide mixture slurry, the solid product is dried to obtain micro-nano oxide powder with an inner hydrophobic and outer hydrophilic structure.

2. The method for modifying micro / nano oxide powder according to claim 1, characterized in that: The hydrophobic modifier is selected from any one or more of hexamethyldisilazane, polymethylhydrosiloxane, sodium dodecylbenzenesulfonate, oleic acid, stearic acid, hexadecyltrimethylammonium bromide, dioctadecyldimethylammonium chloride, γ-glycidyl etheroxypropyltrimethoxysilane, Span 80, and tetraethyl orthosilicate; the hydrophilic modifier is selected from any one or more of citric acid, polyacrylic acid, polyethylene glycol, polyethylene oxide, benzalkonium chloride, and Tween 80.

3. The method for modifying micro / nano oxide powder according to claim 1, characterized in that: In step 1, the micro-nano oxide powder can be any one of various metal oxides and silicon oxide.

4. The method for modifying micro / nano oxide powder according to claim 1, characterized in that: In step 1, the particle size of the micro / nano oxide powder is <100μm; the proportion of the hydrophobic modifier in the hydrophobic modified mixed solution is 0.001wt% to 30wt%; and the solid content of the oxide mixed slurry is 0.1wt% to 100wt%.

5. The method for modifying micro / nano oxide powder according to claim 1, characterized in that: In step 2, the curing temperature is 20–150℃ and the curing time is 0.5–48 hours.

6. The method for modifying micro / nano oxide powder according to claim 1, characterized in that: The freezing temperature in step 3 is -40℃, and the freezing time is 5-8 hours.

7. The method for modifying micro / nano oxide powder according to claim 1, characterized in that: In steps 3 and 6, the drying temperature is -40 to 60°C, the drying time is 0.5 to 48 hours, and the drying methods include baking, vacuum drying, and freeze drying.

8. The method for modifying micro / nano oxide powder according to claim 1, characterized in that: In step 4, the proportion of the hydrophilic modifier in the hydrophilic modified mixed solution is 0.001wt% to 30wt%.

9. The method for modifying micro / nano oxide powder according to claim 1, characterized in that: The solid content of the hydrophobic oxide mixed slurry in step 5 is 0.1wt% to 100wt%.

10. The method for modifying micro / nano oxide powder according to claim 1, characterized in that: In step 5, the stirring rate is 500–2000 rpm, the stirring temperature is 30–60°C, and the stirring time is 0.5–48 h.

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