Temperature and pH dual-response Pickering emulsion gel lubricant as well as preparation and application thereof

Abstract

The invention belongs to the technical field of preparation of lubricating materials, and provides a temperature and pH dual-response Pickering emulsion gel lubricant as well as preparation and application thereof. The temperature and pH dual-response Pickering emulsion gel lubricant disclosed by the invention is a water-in-oil Pickering emulsion gel system, and the temperature and pH dual-response Pickering emulsion gel lubricant is a water-in-oil Pickering emulsion gel system; the water-in-oil Pickering emulsion gel system comprises water, base oil and a nanogel surfactant, wherein the nanogel surfactant is a surface activity community formed by electrostatic assembly of nanogel and an oil-soluble polymer ligand on an oil-water interface. The Pickering emulsion gel lubricant provided by the invention has the advantages of adjustable friction coefficient, underwater 4D printability, excellent air / underwater lubricity and corrosion resistance, and can stably exist for more than one year. The preparation method is simple, and the finished lubricant is good in stability and easy to industrialize.

Description

Technical Field

[0001] This invention relates to the field of lubricant preparation technology, and in particular to a temperature- and pH-responsive Pickering emulsion gel lubricant, its preparation and application. Background Technology

[0002] Lubrication technology, as the "invisible lifeblood" of modern industry, is the cornerstone of ensuring economical, efficient, green, and safe operation, and its strategic significance and economic benefits cannot be ignored. Statistics show that friction-related energy consumption accounts for 30% to 50% of global primary energy consumption, and approximately 60% of mechanical equipment failures stem from poor lubrication or wear. This is not only a huge waste of energy but also directly translates into staggering economic losses. Therefore, the continuous development of high-performance lubricating materials plays a crucial role in improving overall energy efficiency, ensuring the safe and reliable operation of critical equipment, and achieving sustainable development strategic goals.

[0003] However, existing lubricant systems, such as traditional liquid lubricants, semi-solid greases, and solid lubricants, each have their inherent limitations. While liquid lubricants offer excellent flowability and heat dissipation, they are prone to leakage and loss, easily contaminated by wear debris, and struggle to maintain lubrication performance over long periods. Furthermore, they exhibit poor sealing in open or precision systems. Semi-solid greases provide better adhesion, but their structure is prone to instability at high temperatures and speeds, and their ability to contain wear debris is limited. Solid lubricants are suitable for extreme operating conditions, but they typically struggle to form a continuous lubricating film and are inconvenient to replenish. Emerging gel lubricants, while achieving excellent adhesion, sealing, and long-lasting lubrication through their unique three-dimensional network structure, combining the advantages of both liquids and solids to some extent, have largely static and fixed tribological properties, unable to dynamically adjust in response to changes in operating conditions. Therefore, developing a smart semi-solid lubricant material that retains the advantages of traditional lubricants while also possessing environmental responsiveness and a dynamically adjustable coefficient of friction has become a key challenge in improving adaptive lubrication in high-end equipment. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a temperature- and pH-responsive Pickering emulsion gel lubricant, its preparation, and its application. The temperature- and pH-responsive Pickering emulsion gel lubricant provided by this invention exhibits dynamically adjustable tribological properties, allowing for precise and reversible control of the macroscopic coefficient of friction through ambient temperature or pH value, enabling the same material to adapt to different operating conditions.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a temperature and pH dual-responsive Pickering emulsion gel lubricant, wherein the temperature and pH dual-responsive Pickering emulsion gel lubricant is a water-in-oil Pickering emulsion gel system; the water-in-oil Pickering emulsion gel system comprises water, base oil and nanogel surfactant, wherein the nanogel surfactant is a surface-active community formed by the electrostatic assembly of nanogel and oil-soluble polymer ligand at the oil-water interface.

[0006] Preferably, the nanogel is an N-isopropylacrylamide nanogel modified with negatively charged α-methacrylic acid.

[0007] Preferably, the radius of the nanogel is 100~400nm.

[0008] Preferably, the oil-soluble polymer ligand is aminopropyl-terminated polydimethylsiloxane, and the weight-average molecular weight of the aminopropyl-terminated polydimethylsiloxane is 1000~50000.

[0009] Preferably, the aminopropyl dual-terminated polydimethylsiloxane has a weight-average molecular weight of 15,000 to 30,000.

[0010] Preferably, the base oil is one or more of dimethyl silicone oil, liquid paraffin, pentaerythritol oleate, trimethylolpropane oleate, white oil, mineral oil, PAO4, PAO6, PAO8, and PAO10.

[0011] This invention also provides a method for preparing the temperature- and pH-responsive Pickering emulsion gel lubricant, comprising the following steps: The pH value of the aqueous dispersion of the nanogel was adjusted to obtain the aqueous phase; The oil-soluble polymer ligand and base oil are mixed to obtain the oil phase; The aqueous and oil phases are mixed and dispersed to a viscous state, and then allowed to stand to form a gel, thus obtaining the temperature and pH dual-responsive Pickering emulsion gel lubricant.

[0012] Preferably, the concentration of the aqueous dispersion of the nanogel is 8-30 mg / mL; and the pH value is 2-8. The concentration of oil-soluble polymer ligands in the oil phase is 5~30 mg / mL; The aqueous phase accounts for 30-70% of the total volume of the aqueous and oil phases.

[0013] This invention also provides applications of the temperature- and pH-responsive Pickering emulsion gel lubricant or the temperature- and pH-responsive Pickering emulsion gel lubricant prepared by the aforementioned method in the fields of 4D printing, mechanical engineering, deep-sea exploration, and shipbuilding.

[0014] Preferably, the environment in which the application is performed is water or air.

[0015] This invention provides a temperature- and pH-responsive Pickering emulsion gel lubricant.

[0016] In this invention, both the nanogel and the oil-soluble polymer ligand are amphiphilic, allowing them to adsorb at the oil-water interface and reduce interfacial tension. Because the carboxyl groups on the nanogel surface are negatively charged, and the terminal amino groups of the oil-soluble polymer ligand are positively charged, the terminal amino groups of the oil-soluble polymer ligand can spontaneously assemble with the carboxyl groups on the nanogel surface at the oil-water interface through electrostatic interactions to form a nanogel surfactant. The amino groups at both ends of the oil-soluble polymer ligand assemble with the nanogels on different droplet surfaces, acting as a bridge to form a droplet network and binding the oil phase within the network structure to form a W / O type Pickering emulsion gel.

[0017] Furthermore, as the ambient temperature rises, the N-isopropylacrylamide chains in the nanogel hydrophobically shrink, reducing the nanogel particle size. This results in fewer sites at the interface for electrostatic interaction with oil-soluble polymer ligands, causing the nanogel surfactant to disassemble and the gel to become fluid. Upon returning to room temperature, the N-isopropylacrylamide chains hydrophilically swell, increasing the nanogel particle size and the number of active sites for interfacial electrostatic interaction. The nanogel surfactant then reassembles electrostatically at the interface, restoring the gel to a semi-solid state. When the pH is too high or too low (e.g., below the pKa of the carboxyl group or above the pKa of the amino group), the protonation of the amino group or the deprotonation of the carboxyl group is inhibited, weakening the interfacial electrostatic interaction. This leads to the disassembly of the nanogel surfactant at the interface, causing the gel to demulsify. When the pH is between 2 and 8, a sufficient number of protonated amino groups and deprotonated carboxyl groups undergo interfacial electrostatic assembly, and the emulsion gel recrystallizes again.

[0018] The scientific value of this invention lies in its ability to cleverly combine the lubricating properties of base oil with the anti-creep and easy-adhesion properties of semi-solid grease. A structurally stable and performance-tunable semi-solid Pickering emulsion gel lubricant is constructed through the interfacial assembly of a stimulus-responsive nanogel surfactant. This not only achieves strong adhesion of the material at the friction interface, effectively solving the long-standing problem of leakage and loss of liquid lubricants, but also revolutionarily endows it with the ability to intelligently and reversibly adjust its coefficient of friction according to ambient temperature and pH. This means that a single material can adapt to the differentiated frictional requirements of different working stages, thereby fundamentally improving the intelligence level and energy efficiency of equipment operation. Crucially, the Pickering emulsion gel lubricant maintains structural integrity and functional activity even in extreme underwater environments, breaking through the technical barriers of easy dissolution and performance instability of traditional water-based lubricants, providing key material support for the reliable operation of underwater equipment. Furthermore, the excellent rheological properties and responsiveness of the Pickering emulsion gel lubricant enable it to perform underwater 4D printing, further expanding its application scenarios from passive lubrication to the field of programmable intelligent structure manufacturing. Therefore, this invention is not only a high-performance lubricant, but also a future-oriented adaptive intelligent material platform, which has significant practical implications for promoting the intelligent and green upgrading of the high-end equipment manufacturing industry.

[0019] The beneficial effects of this invention are as follows: (1) The Pickering emulsion gel lubricant of the present invention is semi-solid and is not prone to leakage and creep during operation. The nanogel and oil-soluble polymer ligand are firmly adsorbed at the oil-water interface, the aqueous phase is uniformly dispersed in the oil phase in the form of droplets, and the base oil is fixed in the network structure formed by the droplets, thus avoiding the precipitation of the base oil.

[0020] (2) The Pickering emulsion gel lubricant of the present invention exhibits good stability and no obvious demulsification or oil separation phenomenon was observed after being placed at room temperature for more than 1 year.

[0021] (3) The Pickering emulsion gel lubricant of the present invention has excellent friction reduction and anti-wear properties. When used as a lubricant in air, its coefficient of friction is ≤0.07, which is better than that of dimethyl silicone oil, and its wear volume is lower than that of dimethyl silicone oil.

[0022] (4) The Pickering emulsion gel lubricant of the present invention does not disperse in water and can adhere firmly to various substrates, has excellent underwater lubricity, and has a friction coefficient ≤0.04 when used as a lubricant underwater. Its tribological performance is even better than that in air, and it still maintains stable lubrication performance after 400,000 underwater friction cycles.

[0023] (5) The Pickering emulsion gel lubricant of the present invention has dual temperature and pH response, and the friction coefficient of the Pickering emulsion gel lubricant can be reversibly adjusted by changing the ambient temperature or pH value.

[0024] (6) The Pickering emulsion gel lubricant of the present invention has underwater 4D printing properties, which can be molded into a variety of complex shapes in water and the shape can be changed by adjusting the underwater temperature and pH.

[0025] (7) The Pickering gel lubricant of the present invention has excellent corrosion resistance. When it is coated on the surface of a stainless steel block and placed in water at 50°C for 72 hours, no obvious corrosion phenomenon is observed. When it is coated on the surface of a stainless steel electrode for electrochemical corrosion experiment, no corrosion current is observed in a 3.5wt% NaCl aqueous solution, indicating that no electrochemical corrosion occurs.

[0026] This invention also provides a method for preparing the temperature- and pH-responsive Pickering emulsion gel lubricant described in the above-mentioned technical solution. The preparation method of this invention uses few raw materials, is simple, has mild reaction conditions, and high preparation efficiency. The raw materials used are non-toxic and environmentally friendly, and are easily industrialized. Attached Figure Description

[0027] Figure 1 The graph shows the change in the coefficient of friction of Pickering emulsion gel lubricant and dimethyl silicone oil obtained in Example 1 over time in air. Figure 2 The image shows the wear volume of Pickering emulsion gel lubricant and dimethyl silicone oil obtained in Example 1 in air. Figure 3 This is a comparison chart of the coefficients of friction of the Pickering emulsion gel lubricant obtained in Example 1 in air and water; Figure 4 This is a graph showing the coefficient of friction of the Pickering emulsion gel lubricant obtained in Example 1 over a long period of time in water. Figure 5 The graph shows the coefficient of friction of the Pickering emulsion gel lubricant obtained in Example 1 as a function of ambient temperature. Figure 6 The graph shows the coefficient of friction of the Pickering emulsion gel lubricant obtained in Example 1 as a function of the ambient pH value. Figure 7 SEM images and physical photos of stainless steel blocks coated and uncoated with the Pickering emulsion gel lubricant obtained in Example 1 after being placed in water at 50°C for 72 hours; Figure 8The polarization curves are shown for the stainless steel electrode coated with Pickering emulsion gel lubricant obtained in Example 1 and the uncoated stainless steel electrode. Figure 9 The graph shows the changes in shape or pattern printed in water as a function of temperature and pH using the Pickering emulsion gel lubricant obtained in Example 1 as an ink. Detailed Implementation

[0028] This invention provides a temperature and pH dual-responsive Pickering emulsion gel lubricant, wherein the temperature and pH dual-responsive Pickering emulsion gel lubricant is a water-in-oil Pickering emulsion gel system; the water-in-oil Pickering emulsion gel system comprises water, base oil and nanogel surfactant, wherein the nanogel surfactant is a surface-active community formed by the electrostatic assembly of nanogel and oil-soluble polymer ligand at the oil-water interface.

[0029] Unless otherwise specified, the raw materials used in this invention are preferably commercially available products.

[0030] The temperature- and pH-responsive Pickering emulsion gel lubricant provided by this invention is a water-in-oil Pickering emulsion gel system.

[0031] In this invention, the temperature- and pH-responsive Pickering emulsion gel lubricant contains water, preferably pure water.

[0032] In this invention, the temperature- and pH-responsive Pickering emulsion gel lubricant comprises a base oil, preferably one or more of dimethyl silicone oil, liquid paraffin, pentaerythritol oleate, trimethylolpropane oleate, white oil, mineral oil, PAO4, PAO6, PAO8, and PAO10. In this invention, the polarity of the base oil has a significant impact on the formation of the Pickering emulsion gel lubricant; non-polar and low-polarity oils, such as n-hexane and dodecane, will be difficult to form a Pickering emulsion gel lubricant.

[0033] In this invention, the temperature and pH dual-responsive Pickering emulsion gel lubricant contains a nanogel surfactant, which is a surface-active community formed by the electrostatic assembly of nanogel and oil-soluble polymer ligand at the oil-water interface.

[0034] In this invention, the nanogel is preferably an N-isopropylacrylamide nanogel modified with α-methacrylic acid and carrying a negatively charged surface. In this invention, the radius of the nanogel is preferably 100-400 nm, specifically 100 nm, 120 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, or 400 nm. In this invention, the nanogel is an N-isopropylacrylamide nanogel modified with α-methacrylic acid, which has an amphiphilic surface due to its negative charge and can be adsorbed at the oil-water interface during emulsification to reduce the interfacial tension between oil and water.

[0035] In this invention, the oil-soluble polymer ligand is preferably aminopropyl-terminated polydimethylsiloxane, wherein the weight-average molecular weight (M) of the aminopropyl-terminated polydimethylsiloxane is... W The preferred concentration is 1000~50000, more preferably 15000~30000, and specifically preferably 20000, 25000, 27000, 30000, 35000, 40000, 45000, or 50000. In this invention, the oil-soluble polymer ligand is a positively charged amphiphilic polymer, which can assemble with the carboxyl groups on the surface of the nanogel at the oil-water interface through electrostatic interactions to construct a nanogel surfactant.

[0036] The Pickering emulsion gel lubricant provided by this invention is a semi-solid material that is both temperature- and pH-responsive. It cleverly combines the characteristics of liquid lubricants and semi-solid greases. The structure is stabilized by a nanogel surfactant, effectively preventing lubricant loss. Furthermore, it can intelligently and reversibly adjust the coefficient of friction according to ambient temperature and pH, achieving adaptive lubrication. This dual-response characteristic to temperature and pH, combined with its semi-solid rheological behavior, makes it an ideal 4D printing smart material. It can be printed into specific three-dimensional structures and undergo programmable shape transformations under environmental stimuli, showing great potential in fields such as intelligent sealing and adaptive soft robotics. This expands the function of lubricating materials from friction reduction and wear resistance to programmable intelligent adaptation and structural-functional integration. The Pickering emulsion gel lubricant of this invention does not disintegrate underwater, meaning it is structurally stable in underwater environments, opening up new avenues for underwater lubrication. The temperature- and pH-responsive Pickering emulsion gel lubricant provided by this invention has excellent air / underwater lubricity and corrosion resistance, adjustable coefficient of friction, underwater 4D printing capability, and can remain stable for more than 1 year; when used as a lubricant in air, the coefficient of friction is ≤0.07, and when used as a lubricant underwater, the coefficient of friction is ≤0.04.

[0037] This invention also provides a method for preparing the temperature and pH dual-responsive Pickering emulsion gel lubricant, comprising the following steps: The pH value of the aqueous dispersion of the nanogel was adjusted to obtain the aqueous phase; The oil-soluble polymer ligand and base oil are mixed to obtain the oil phase; The aqueous and oil phases are mixed and dispersed to a viscous state, and then allowed to stand to form a gel, thus obtaining the temperature and pH dual-responsive Pickering emulsion gel lubricant.

[0038] This invention adjusts the pH value of the aqueous dispersion of nanogels to obtain an aqueous phase.

[0039] In this invention, the concentration of the aqueous dispersion of the nanogel is preferably 8-30 mg / mL, more preferably 15-25 mg / mL, and specifically preferably 8 mg / mL, 10 mg / mL, 12 mg / mL, 15 mg / mL, 18 mg / mL, 20 mg / mL, 22 mg / mL, 25 mg / mL, 28 mg / mL, or 30 mg / mL. In this invention, the concentration of the aqueous dispersion of the nanogel has a significant impact on the formation of Pickering emulsion gel; if the concentration is too low or too high, Pickering emulsion gel cannot be formed.

[0040] In this invention, the method for preparing the aqueous dispersion of the nanogel preferably includes the following steps: Under a protective atmosphere, N-isopropylacrylamide, N,N-methylenebisacrylamide, and α-methacrylic acid are dissolved in water, and the system is adjusted to alkalinity for a first reaction. Then, potassium persulfate is added to carry out a second reaction, yielding an aqueous dispersion of the nanogel. In this invention, the protective atmosphere is preferably nitrogen. In this invention, the preferred mass ratio of N-isopropylacrylamide to N,N-methylenebisacrylamide is 3.089:0.1075; the preferred mass ratio of N,N-methylenebisacrylamide to α-methacrylic acid is 0.1075:0.1072; and the preferred volume ratio of N-isopropylacrylamide to water is 3.089 g:140 mL. In this invention, the preferred pH value of the alkaline solution is 10.8. In this invention, the preferred temperature for the first reaction is 70°C, the preferred time is 40 min, and the first reaction is preferably carried out under stirring. In this invention, the preferred mass ratio of N-isopropylacrylamide to potassium persulfate is 3.089:0.031. In this invention, the potassium persulfate is preferably used in the form of a potassium persulfate solution. In this invention, the temperature of the second reaction is preferably 70°C, the time is preferably 7 hours, and the second reaction is preferably carried out under stirring. After the second reaction, this invention preferably further includes: cooling the obtained reaction solution to room temperature, centrifuging, collecting the precipitate; dialyzing the precipitate for 7 days and diluting it to obtain an aqueous dispersion of the nanogel. In this invention, the centrifugation speed is preferably 10,000 rpm, and the time is preferably 1 hour. This invention does not limit the dilution factor; it can be determined according to actual needs.

[0041] In this invention, the pH value is preferably 2-8, more preferably 2-6, and specifically preferably 2, 3, 4, 5, 6, 7, or 8. The reagent used to adjust the aqueous dispersion of the nanogel to acidity is preferably an inorganic acid or an inorganic base. The inorganic acid is preferably used in the form of an inorganic acid solution, and the inorganic acid solution is preferably a hydrochloric acid solution with a concentration of 1 mol / L. The inorganic base is preferably used in the form of an inorganic base solution, and the inorganic base solution is preferably a sodium hydroxide solution with a concentration of 1 mol / L. In this invention, the pH value of the aqueous dispersion of the nanogel has a significant impact on the formation of the Pickering emulsion gel lubricant. If the system is too alkaline or too acidic, for example, with a pH value greater than 8 or less than 2, it will be difficult to form the Pickering emulsion gel lubricant.

[0042] This invention mixes an oil-soluble polymer ligand with a base oil to obtain an oil phase.

[0043] In this invention, the concentration of the oil-soluble polymer ligand in the oil phase is preferably 5-30 mg / mL, more preferably 15-25 mg / mL, and specifically preferably 5 mg / mL, 10 mg / mL, 15 mg / mL, 20 mg / mL, 25 mg / mL, or 30 mg / mL. In this invention, the concentration of the oil-soluble polymer ligand in the oil phase has a significant impact on the formation of the Pickering emulsion gel lubricant; if the concentration of the polymer ligand is too low, it will be difficult to form the Pickering emulsion gel lubricant.

[0044] After obtaining the aqueous phase and the oil phase, the present invention mixes and disperses the aqueous phase and the oil phase until they reach a viscous state, and allows them to stand to form a gel, thereby obtaining the temperature and pH dual-response Pickering emulsion gel lubricant.

[0045] In this invention, the aqueous phase preferably accounts for 30-70% of the total volume of the aqueous and oil phases, more preferably 40-60%, and specifically preferably 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, or 70%. In this invention, the volume ratio of the aqueous phase to the oil phase has a significant impact on the formation of the Pickering emulsion gel lubricant. If the volume percentage of the aqueous phase is too low or too high, for example, less than 30% or greater than 70%, it will be difficult to form the Pickering emulsion gel lubricant.

[0046] In this invention, the preferred method for mixing the aqueous phase and the oil phase is to add the oil phase into the aqueous phase.

[0047] In this invention, the dispersion method is preferably magnetic stirring or vortex oscillation. The magnetic stirring speed is preferably 500-3000 rpm, and the dispersion time is preferably 10 minutes.

[0048] In this invention, the settling time is preferably 0.2 to 2 hours, and more preferably 0.5 hours.

[0049] This invention also provides applications of the temperature- and pH-responsive Pickering emulsion gel lubricant or the temperature- and pH-responsive Pickering emulsion gel lubricant prepared by the aforementioned method in the fields of 4D printing, mechanical engineering, deep-sea exploration, and shipbuilding.

[0050] In this invention, the 4D printing preferably includes smart sealing and adaptive soft robots.

[0051] In this invention, the environment in which the application is performed is preferably water or air.

[0052] The temperature- and pH-responsive Pickering emulsion gel lubricant provided by this invention exhibits structural stability in underwater environments and possesses both underwater lubrication and 4D printing capabilities. This overcomes the limitations of traditional water-based lubricants and provides a new programmable smart material platform for fields such as intelligent sealing and soft robotics. The temperature- and pH-responsive Pickering emulsion gel lubricant provided by this invention has a coefficient of friction ≤0.07 when used as a lubricant in air and ≤0.04 when used underwater, giving it excellent lubricity in both water and air.

[0053] The following detailed description, in conjunction with embodiments, illustrates the temperature- and pH-responsive Pickering emulsion gel lubricant provided by the present invention, as well as its preparation and application. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0054] Example 1 A method for preparing a temperature- and pH-responsive Pickering emulsion gel lubricant includes the following steps: The prepared aqueous dispersion of the nanogel was diluted to 20 mg / mL, and the pH of the dispersion was adjusted to 4 with 1 mol / L HCl solution to form the aqueous phase. Aminopropyl dimethylsiloxane (M...) was then added... W =27000) was dissolved in dimethyl silicone oil to prepare a polymer ligand oil solution with a concentration of 20 mg / mL as the oil phase. The oil phase was poured into the aqueous phase at a ratio of 50% by volume. After vortexing for 10 min, the mixture became viscous. It was then allowed to stand for 0.5 h until it gelled, and the product was obtained.

[0055] The preparation method of the aqueous dispersion of the nanogel includes the following steps: 3.089 g of N-isopropylacrylamide, 0.1075 g of N,N-methylenebisacrylamide, and 0.1072 g of α-methacrylic acid are dissolved in 140 mL of water, poured into a three-necked flask, and N2 is introduced to remove O2 from the flask. The pH of the system is adjusted to 10.8, and the mixture is stirred at 70 °C for 40 min. Then, 10 mL of potassium persulfate (0.031 g) solution is added, and the mixture is stirred at 70 °C for 7 h. After cooling, the mixture is centrifuged at 10000 rpm for 1 h. The precipitate is dialyzed for 7 days to obtain a high-concentration nanogel dispersion, which is then diluted with water to 20 mg / mL. The radius of the nanogel is 120 nm.

[0056] Example 2 A method for preparing a temperature- and pH-responsive Pickering emulsion gel lubricant includes the following steps: The prepared nanogel aqueous dispersion was diluted to 20 mg / mL, and the pH of the dispersion was adjusted to 6 with 1 mol / L HCl solution to form the aqueous phase. Aminopropyl dimethylsiloxane (M... W =27000) was dissolved in dimethyl silicone oil to prepare a polymer ligand oil solution with a concentration of 20 mg / mL as the oil phase. The oil phase was poured into the aqueous phase at a ratio of 50% by volume. After vortexing for 10 min, the mixture became viscous. It was then allowed to stand for 0.5 h until it gelled, and the product was obtained.

[0057] The preparation of the aqueous dispersion of the nanogel is the same as in Example 1.

[0058] Example 3 A method for preparing a temperature- and pH-responsive Pickering emulsion gel lubricant includes the following steps: The prepared aqueous dispersion of the nanogel was diluted to 30 mg / mL, and the pH of the dispersion was adjusted to 4 with 1 mol / L HCl solution to form the aqueous phase. Aminopropyl dimethylsiloxane (M... W =27000) was dissolved in dimethyl silicone oil to prepare a polymer ligand oil solution with a concentration of 20 mg / mL as the oil phase. The oil phase was poured into the aqueous phase at a ratio of 50% by volume. After vortexing for 10 min, the mixture became viscous. It was then allowed to stand for 0.5 h until it gelled, and the product was obtained.

[0059] The preparation of the aqueous dispersion of the nanogel is the same as in Example 1.

[0060] Example 4 A method for preparing a temperature- and pH-responsive Pickering emulsion gel lubricant includes the following steps: The prepared aqueous dispersion of the nanogel was diluted to 20 mg / mL, and the pH of the dispersion was adjusted to 4 with 1 mol / L HCl solution to form the aqueous phase. Aminopropyl dimethylsiloxane (M...) was then added... W =27000) was dissolved in dimethyl silicone oil to prepare a polymer ligand oil solution with a concentration of 10 mg / mL as the oil phase. The oil phase was poured into the aqueous phase at a ratio of 50% by volume. After vortexing for 10 min, the mixture became viscous. It was then allowed to stand for 0.5 h until it gelled, and the product was obtained.

[0061] The preparation of the aqueous dispersion of the nanogel is the same as in Example 1.

[0062] Example 5 A method for preparing a temperature- and pH-responsive Pickering emulsion gel lubricant includes the following steps: The prepared aqueous dispersion of the nanogel was diluted to 20 mg / mL, and the pH of the dispersion was adjusted to 4 with 1 mol / L HCl solution to form the aqueous phase. Aminopropyl dimethylsiloxane (M...) was then added... W =10000) was dissolved in dimethyl silicone oil to prepare a polymer ligand oil solution with a concentration of 20 mg / mL as the oil phase. The oil phase was poured into the aqueous phase at a volume ratio of 50%, and after vortexing for 10 min, the mixture became viscous. After standing for 0.5 h until it gelled, the product was obtained.

[0063] The preparation of the aqueous dispersion of the nanogel is the same as in Example 1.

[0064] Example 6 A method for preparing a temperature- and pH-responsive Pickering emulsion gel lubricant includes the following steps: The prepared aqueous dispersion of the nanogel was diluted to 20 mg / mL, and the pH of the dispersion was adjusted to 4 with 1 mol / L HCl solution to form the aqueous phase. Aminopropyl dimethylsiloxane (M...) was then added... W =27000) was dissolved in dimethyl silicone oil to prepare a polymer ligand oil solution with a concentration of 20 mg / mL as the oil phase. The oil phase was poured into the aqueous phase at a volume ratio of 60%, and after vortexing for 10 min, the mixture became viscous. After standing for 0.5 h until it gelled, the product was obtained.

[0065] The preparation of the aqueous dispersion of the nanogel is the same as in Example 1.

[0066] Example 7 A method for preparing a temperature- and pH-responsive Pickering emulsion gel lubricant includes the following steps: The prepared aqueous dispersion of the nanogel was diluted to 20 mg / mL, and the pH of the dispersion was adjusted to 4 with 1 mol / L HCl solution to form the aqueous phase. Aminopropyl dimethylsiloxane (M...) was then added... W =27000) was dissolved in pentaerythritol oleate to prepare a polymer ligand oil solution with a concentration of 20 mg / mL as the oil phase. The oil phase was poured into the aqueous phase at a ratio of 50% by volume. After vortexing for 10 min, the mixture became viscous. It was then allowed to stand for 0.5 h to form a gel, which yielded the final product.

[0067] The preparation of the aqueous dispersion of the nanogel is the same as in Example 1.

[0068] Comparative Example 1 The prepared nanogel aqueous dispersion was diluted to 20 mg / mL, and the pH of the dispersion was adjusted to 10 with 1 mol / L NaOH solution to serve as the aqueous phase. Aminopropyl dimethylsiloxane (M... W =27000) was dissolved in dimethyl silicone oil to prepare a polymer ligand oil solution with a concentration of 20 mg / mL as the oil phase. The oil phase was poured into the aqueous phase at a volume ratio of 50%. After vortexing for 10 min, the mixture showed phase separation upon standing, failing to form a Pickering emulsion gel. This indicates that the pH value of the aqueous dispersion of the nanogel is too high, which is unfavorable for the formation of the Pickering emulsion gel lubricant.

[0069] The preparation of the aqueous dispersion of the nanogel is the same as in Example 1.

[0070] Comparative Example 2 The prepared aqueous dispersion of the nanogel was diluted to 4 mg / mL, and the pH of the dispersion was adjusted to 4 with 1 mol / L HCl solution to form the aqueous phase. Aminopropyl dimethylsiloxane (M...) was then added... W =27000) was dissolved in dimethyl silicone oil to prepare a polymer ligand oil solution with a concentration of 20 mg / mL as the oil phase. The oil phase was poured into the aqueous phase at a volume ratio of 50%. After vortexing for 10 min, the mixture showed phase separation after standing, failing to form a Pickering emulsion gel. This indicates that the concentration of the aqueous dispersion of the nanogel was too low, which is detrimental to the formation of the Pickering emulsion gel lubricant.

[0071] The preparation of the aqueous dispersion of the nanogel is the same as in Example 1.

[0072] Comparative Example 3 The prepared aqueous dispersion of the nanogel was diluted to 20 mg / mL, and the pH of the dispersion was adjusted to 4 with 1 mol / L HCl solution to form the aqueous phase. Aminopropyl dimethylsiloxane (M...) was then added... W=27000) was dissolved in dimethyl silicone oil to prepare a polymer ligand oil solution with a concentration of 5 mg / mL as the oil phase. The oil phase was poured into the aqueous phase at a volume ratio of 50%. After vortexing for 10 minutes, the mixture showed phase separation upon standing, failing to form a Pickering emulsion gel. This indicates that the concentration of polymer ligands in the oil phase is too low, which is detrimental to the formation of the Pickering emulsion gel lubricant.

[0073] The preparation of the aqueous dispersion of the nanogel is the same as in Example 1.

[0074] Comparative Example 4 The prepared aqueous dispersion of the nanogel was diluted to 20 mg / mL, and the pH of the dispersion was adjusted to 4 with 1 mol / L HCl solution to form the aqueous phase. Aminopropyl dimethylsiloxane (M...) was then added... W =27000) was dissolved in dimethyl silicone oil to prepare a polymer ligand oil solution with a concentration of 20 mg / mL as the oil phase. The oil phase was poured into the aqueous phase at a volume ratio of 80%. After vortexing for 10 minutes, the mixture showed phase separation upon settling, failing to form a Pickering emulsion gel. This indicates that an insufficient volume ratio of the aqueous phase is detrimental to the formation of the Pickering emulsion gel lubricant.

[0075] The preparation of the aqueous dispersion of the nanogel is the same as in Example 1.

[0076] Comparative Example 5 The prepared aqueous dispersion of the nanogel was diluted to 20 mg / mL, and the pH of the dispersion was adjusted to 4 with 1 mol / L HCl solution to form the aqueous phase. Aminopropyl dimethylsiloxane (M...) was then added... W =27000) was dissolved in dodecane to prepare a polymer ligand oil solution with a concentration of 20 mg / mL as the oil phase. The oil phase was poured into the aqueous phase at a volume ratio of 50%. After vortexing for 10 minutes, the mixture showed phase separation upon settling, failing to form a Pickering emulsion gel. This indicates that improper selection of the base oil is detrimental to the formation of Pickering emulsion gel lubricants.

[0077] The preparation of the aqueous dispersion of the nanogel is the same as in Example 1.

[0078] Test Example 1 The frictional properties of the Pickering emulsion gel lubricant prepared in Example 1 were characterized under air, underwater, and different temperatures and pH conditions. The results are as follows: Figures 1-6 As shown.

[0079] Friction and wear performance test, the test conditions are: friction pair is Si3N4 ball / steel block, load is 20N, frequency is 30Hz.

[0080] Figure 1 and Figure 2 The results show that the Pickering emulsion gel lubricant obtained in Example 1 has a better lubrication effect than dimethyl silicone oil, and can effectively reduce the friction coefficient of the system to 0.07, and the wear volume is reduced to about 75% of that of the dimethyl silicone oil lubrication system.

[0081] Figure 3 The graph shows a comparison of the coefficient of friction of the Pickering emulsion gel lubricant obtained in Example 1 in air and water. The results show that the Pickering emulsion gel lubricant obtained in Example 1 can still maintain excellent lubrication performance in water, which is lower than the coefficient of friction in air.

[0082] Figure 4 The graph shows the coefficient of friction of the Pickering emulsion gel lubricant obtained in Example 1 under long-term friction in water. The results show that the Pickering emulsion gel lubricant obtained in Example 1 can maintain stable and excellent lubrication performance under long-term friction in water.

[0083] Figure 5 , Figure 6 The curves show the coefficient of friction of the Pickering emulsion gel lubricant obtained in Example 1 as a function of ambient temperature and pH value. The results indicate that the lubrication performance of the Pickering emulsion gel lubricant obtained in Example 1 can be reversibly adjusted according to environmental changes.

[0084] Test Example 2 The corrosion resistance of the Pickering emulsion gel lubricant prepared in Example 1 was tested, such as... Figure 7 and Figure 8 As shown.

[0085] Figure 7 The images show surface images and SEM images of stainless steel blocks coated and uncoated with the Pickering emulsion gel lubricant obtained in Example 1 after being placed in water at 50°C for 72 hours. The left image shows the SEM image and physical image of the pure stainless steel block (see the inset of the left image); the middle image shows the surface SEM image and physical image of the stainless steel block without Pickering emulsion gel lubricant after corrosion reaction in water (see the inset of the middle image); and the right image shows the surface SEM image and physical image of the stainless steel block coated with Pickering emulsion gel lubricant after corrosion reaction in water (see the inset of the right image). The results show that the surface of the uncoated stainless steel block exhibits severe corrosion, while the surface of the stainless steel block coated with Pickering emulsion gel lubricant is similar to that of the pure steel block, with no obvious corrosion.

[0086] Figure 8 The figures show the polarization curves of a stainless steel electrode coated with the Pickering emulsion gel lubricant obtained in Example 1 (corresponding to Example 1 in the figure) and an uncoated stainless steel electrode (corresponding to the blank control in the figure) in a 3.5 wt% NaCl aqueous solution. The results show that the stainless steel electrode coated with the Pickering emulsion gel lubricant obtained in Example 1 did not exhibit corrosion current, further proving that the Pickering emulsion gel lubricant has excellent corrosion resistance.

[0087] Test Example 3 The Pickering emulsion gel lubricant obtained in Example 1 was used as ink for 4D printing in water, such as... Figure 9 As shown.

[0088] Figure 9 The graph shows the changes in shape or pattern printed in water as a result of temperature and pH using the Pickering emulsion gel lubricant obtained in Example 1. The shape or pattern changes with the ambient temperature and pH value, indicating that the Pickering emulsion gel lubricant has the function of underwater 4D printing.

[0089] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A temperature- and pH-responsive Pickering emulsion gel lubricant, wherein the temperature- and pH-responsive Pickering emulsion gel lubricant is a water-in-oil Pickering emulsion gel system; the water-in-oil Pickering emulsion gel system comprises water, base oil, and nanogel surfactant, wherein the nanogel surfactant is a surface-active community formed by the electrostatic assembly of nanogel and oil-soluble polymer ligand at the oil-water interface.

2. The Pickering emulsion gel lubricant according to claim 1, characterized in that, The nanogel is an N-isopropylacrylamide nanogel modified with negatively charged α-methacrylic acid.

3. The Pickering emulsion gel lubricant according to claim 1 or 2, characterized in that, The radius of the nanogel is 100~400nm.

4. The Pickering emulsion gel lubricant according to claim 1, characterized in that, The oil-soluble polymer ligand is aminopropyl-terminated polydimethylsiloxane, and the weight-average molecular weight of the aminopropyl-terminated polydimethylsiloxane is 1000~50000.

5. The Pickering emulsion gel lubricant according to claim 4, characterized in that, The weight-average molecular weight of the aminopropyl dual-terminated polydimethylsiloxane is 15,000 to 30,000.

6. The Pickering emulsion gel lubricant according to claim 1, characterized in that, The base oil is one or more of dimethyl silicone oil, liquid paraffin, pentaerythritol oleate, trimethylolpropane oleate, white oil, mineral oil, PAO4, PAO6, PAO8, and PAO10.

7. A method for preparing the temperature- and pH-responsive Pickering emulsion gel lubricant according to any one of claims 1 to 6, characterized in that, Includes the following steps: The pH value of the aqueous dispersion of the nanogel was adjusted to obtain the aqueous phase; The oil-soluble polymer ligand and base oil are mixed to obtain the oil phase; The aqueous and oil phases are mixed and dispersed to a viscous state, and then allowed to stand to form a gel, thus obtaining the temperature and pH dual-responsive Pickering emulsion gel lubricant.

8. The preparation method according to claim 7, characterized in that, The concentration of the aqueous dispersion of the nanogel is 8~30 mg / mL; the pH value is 2~8; The concentration of oil-soluble polymer ligands in the oil phase is 5~30 mg / mL; The aqueous phase accounts for 30-70% of the total volume of the aqueous and oil phases.

9. The application of the temperature- and pH-responsive Pickering emulsion gel lubricant according to any one of claims 1 to 6, or the temperature- and pH-responsive Pickering emulsion gel lubricant prepared by the preparation method according to claim 7 or 8, in the fields of 4D printing, mechanical engineering, deep-sea exploration, and shipbuilding engineering.

10. The application according to claim 9, characterized in that, The application environment is water or air.

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