Okra lubricant as well as preparation method and application thereof

Abstract

The invention provides an okra lubricant as well as a preparation method and application thereof. The abelmoschus esculentus lubricant is obtained by mixing abelmoschus esculentus mucus powder with a NaCl solution, and the abelmoschus esculentus mucus powder is prepared by a soaking method and contains components such as a water-soluble polysaccharide compound, vegetable protein and mineral substances. And mixing the okra hydrogel with acrylamide, N, N-methylene bisacrylamide and a photoinitiator, stirring, carrying out ultrasonic degassing, and carrying out ultraviolet curing to obtain the okra hydrogel lubricant. The abelmoschus esculentus lubricant and the abelmoschus esculentus hydrogel lubricant prepared by the preparation method disclosed by the invention have good stability, adsorbability, lubricity and wear resistance, and meanwhile, good biological safety is ensured. And the preparation method is simple, the cost is low, and the lubricating grease has the characteristic of super lubrication (friction coefficient [mu] lt: 0.01) under high loading, and can meet the requirement on low friction in practical application.

Description

Technical Field

[0001] The invention relates to an okra lubricant and a preparation method and application thereof, and belongs to the field of natural plant extraction and hydrogel. Background Art

[0002] Lubricants (such as engine oil and lubricating oil) are commonly used for wear protection of mechanical processing, automobiles and cartilage joints. Compared with traditional mineral oil-based lubricants, biolubricants have attracted much attention for their good degradability, renewability, non-toxicity and priority during use. Bio-oil-based lubricants such as palm oil, rapeseed oil, tobacco seed oil and animal fats have shown good lubrication and anti-wear properties in previous studies. For example, Chinese patent document CN117625147A discloses a palm oil-based lubricant for drilling fluid and a preparation method thereof. By epoxidation modification of palm oil and optimal compounding of additives, the oxidation stability of palm oil is improved, the viscosity is reduced, and the hydrolysis reaction of palm oil molecules is reduced, so that it has good anti-mild lubrication performance and is used for drilling construction with high requirements for lubricant high temperature resistance and lubrication performance. In addition, there are also a large number of studies on biological water-based lubricants extracted from natural plants, which generally have the characteristics of environmental protection, anti-combustion, high fluidity and thermal conductivity. For example, Chinese patent document CN107376034A discloses a plant polypeptide water-soluble lubricant and a preparation method thereof, wherein plant polypeptide, glycerol, polyethylene glycol, carbomer, vaseline, phenoxyethanol and water are uniformly mixed to obtain the plant polypeptide water-soluble lubricant. The invention achieves the technical effects of being non-toxic, harmless, colorless, tasteless, non-greasy, easy to clean, safe and hygienic, non-irritating to the human body, non-sensitizing, and having better lubricity through the systematic coordination of each component. At present, the production cost of lubricants is high, the process is complex, the cycle is long, and some substances harmful to the human body and the environment may be involved. In some cases, the lubrication effect does not meet the actual requirements.

[0003] Okra is a fast-growing annual herb widely distributed in tropical regions. Okra is a well-known culinary food due to its high fiber, antioxidant and mineral content. Previous studies have shown that okra mucus extracted from okra plants can be used to treat wounds, ulcers and inflammation, or as a drug with analgesic effects on diabetes, dysentery and cramps. In addition, the chemical composition of okra mucus has been studied and found that its main components are water-soluble polysaccharide complexes, minerals and plant proteins. Similar to cabbage, okra's slippery surface in aqueous solution and smooth feeling in the mouth suggest that okra mucus can also act as a biolubricant. Previous studies have shown that the addition of natural okra polysaccharides at a concentration of 2wt% in aqueous lubricant formulations can reduce friction-induced surface deformation, thereby reducing the friction coefficient and wear loss by 50%. Another study applied okra mucus as an environmentally friendly and non-toxic shale swelling inhibitor in water-based drilling fluids, reducing clay swelling by 28.5% to 50.5% at concentrations of 5% to 20%. Studies have shown that okra mucus can improve rheological properties, reduce fluid loss, and provide lubricity, making it a green alternative to traditional clay stabilizers.

[0004] In the current extraction methods of okra effective substances, the pretreatment process generally adopts destructive operations such as crushing and beating, such as Chinese patent documents CN109422822A, CN109453213A, etc., which will cause the ineffective substances in okra to remain in the product, making the impurity removal process complicated and even affecting the subsequent use. The lubricating effect of okra extract has been reported in the prior art. A large number of inventions use okra extract as an additive component of lubricants to enhance the lubrication performance, but there is no lubricant with okra extract as the main component. Lubricants with okra extract as the main component can ensure good biological safety. Hydrogel is a soft material with extremely high water content and has the potential to be used as a biological lubricant. For example, Chinese patent document CN116874914A discloses a composite material based on a soft / hard dual network lubricant and a preparation method, in which ultra-high molecular weight polyethylene is used as a continuous phase, and DN hydrogel particles as a dispersed phase are uniformly distributed inside the continuous phase in a lattice structure, wherein the DN hydrogel microspheres include a PAAm soft network and a UF hard network. However, the prior art does not introduce okra into the hydrogel lubricant, nor does it contain okra extract in the super-lubricating hydrogel. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides an okra lubricant and a preparation method and application thereof. The okra hydrogel lubricant provided by the present invention has a simple preparation method, low cost, good biosafety, and has super lubrication properties under high load conditions, which can meet the requirements for low friction in practical applications.

[0006] The technical solution of the present invention is as follows: A method for preparing an okra lubricant comprises the following steps: (1) The okra that has been seeded and sliced ​​in advance is soaked in deionized water under stirring at room temperature, and then filtered through pasteurized cheese cloth and centrifuged to obtain a raw okra mucus solution; (2) adding acetone to the raw okra mucus solution, dissolving the precipitated white flocs in ethanol, and precipitating them again in acetone. Repeating the purification three times, washing, drying, and grinding to obtain okra mucus powder; (3) Add okra mucus powder into NaCl solution and stir to dissolve to obtain okra lubricant.

[0007] Preferably according to the present invention, in step (1), the weight percentage of deionized water is 10%-40%, and more preferably, the weight percentage of deionized water is 20%; and the soaking time is 24 hours.

[0008] Preferably according to the present invention, in step (1), the centrifugal speed is 7200 rpm and the centrifugal time is 20 min.

[0009] Preferably, according to the present invention, in step (2), the volume of acetone is 5 times that of the raw okra mucus solution.

[0010] Preferably, according to the present invention, in step (2), the solvent used for washing is acetone; and the drying condition is room temperature air.

[0011] Preferably according to the present invention, the salt concentration of the NaCl solution in step (3) is 1 mM.

[0012] Preferably according to the present invention, the mass concentration of the okra mucus powder in step (3) is 0.5-5 mg / mL, more preferably 5 mg / mL.

[0013] Preferably, according to the present invention, the stirring and dissolving temperature in step (3) is room temperature; the stirring and dissolving time is 5-20 min, more preferably 10 min.

[0014] The invention also provides an okra hydrogel lubricant, which comprises the following raw materials: acrylamide (AM), a photoinitiator, N,N-methylenebisacrylamide (BAM) and okra lubricant.

[0015] Preferably according to the present invention, the photoinitiator is photoinitiator 2959, whose Chinese name is 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone.

[0016] Preferably according to the present invention, the mass of the photoinitiator is 1.5% of the mass of acrylamide; the mass of N,N-methylenebisacrylamide is 1.5% of the mass of acrylamide; and the mass ratio of the okra lubricant to acrylamide is 3:1.

[0017] The preparation method of the okra hydrogel lubricant comprises the following steps: ① dissolving acrylamide, photoinitiator and N,N-methylenebisacrylamide in okra lubricant to obtain okra hydrogel precursor solution; ② The precursor solution is stirred, ultrasonically degassed, and then UV-cured to obtain the okra hydrogel lubricant.

[0018] According to the preferred embodiment of the present invention, the stirring time in step ② is 15-30 min, more preferably 20 min.

[0019] Preferably according to the present invention, the ultrasonic degassing time in step ② is 5-20 min, more preferably 10 min.

[0020] Preferably according to the present invention, the UV curing time in step ② is 20-40 minutes, more preferably 30 minutes.

[0021] The present invention also provides the application of the okra mucus water-based lubricant in adsorption on the model surface, exploration of lubrication mechanism and hydration lubricating additive.

[0022] The okra mucus powder of the present invention is white powder, which is convenient for long-term storage, mainly contains water-soluble polysaccharide complex (composed of galacturonic acid, neutral galactose, rhamnose and glucose, and a small amount of fructose, methyl pentose and xylose), plant protein and minerals, has clear ingredients and high purity, and is convenient for subsequent impurity removal and purification operations.

[0023] The okra lubricant provided by the present invention is a non-Newtonian fluid that exhibits shear-thinning behavior. Related viscosity experiments show that it has good stability and can be used to develop stable biological lubricants. The adsorption behavior of the okra lubricant provided by the present invention on the mica surface shows that the okra lubricant can be slowly adsorbed onto the mica to form a softer adsorption layer, and exhibits a strong spatial repulsion in the process of approaching or moving away from the adsorption layers. The slight hysteresis repulsion and non-adhesion enable the okra lubricant to be used for interface lubrication. The adsorption behavior of the okra lubricant provided by the present invention and the formation of the adsorption layer are affected by intermolecular interactions and surface properties, thereby achieving the regulation of its lubricity and anti-wear properties.

[0024] The okra hydrogel lubricant provided by the present invention has super lubrication properties under high loading conditions. When the okra lubricant is added to the polyacrylamide hydrogel, a lubricating film is formed on the surface of the okra hydrogel lubricant due to the hydration of the polymer chain and the polysaccharide, and the polysaccharide diffused into the lubricating film can be adsorbed onto the surface of the substrate and form an additional hydration film, which hinders the direct contact between the substrate and the hydrogel surface, thereby significantly reducing the friction coefficient.

[0025] Technical features and beneficial effects of the present invention: (1) The okra extraction method provided by the present invention adopts an immersion method, the preparation method is simple, environmentally friendly, the okra mucus powder has high purity, and can be stored for a long time. The okra mucus powder extraction method provided by the present invention does not perform destructive operations on okra, but adopts an immersion method. While extracting effective substances in okra, it greatly reduces the possibility of ineffective substances in okra being mixed into the okra mucus powder, improves the purity of the okra mucus powder, and simplifies the subsequent impurity removal and purification process. The operations involved in the extraction process include immersion, stirring, extraction, etc., and are carried out at room temperature and in an air environment. It is easy to implement, has low equipment requirements, and has industrial promotion value. Deionized water, ethanol and acetone are used as solvents in the extraction process, which are easy to recycle and are environmentally friendly.

[0026] (2) The okra lubricant provided by the present invention uses okra mucus powder as the main component, and has good stability, adsorption, lubricity and wear resistance while ensuring good biological safety. The okra lubricant provided by the present invention includes the above-mentioned okra mucus powder and NaCl solution, and the preparation method is simple and can be produced on an industrial scale.

[0027] (3) The okra hydrogel lubricant provided by the present invention has good biosafety. The okra hydrogel lubricant provided by the present invention is obtained by adding the above-mentioned okra lubricant to a traditional polyacrylamide hydrogel. The preparation method is simple and the cost is low. The preparation process and related products will not have adverse effects on the human body and the environment under the conditions of correct operation and treatment, and have good biosafety.

[0028] (4) The okra hydrogel lubricant provided by the present invention has super lubrication properties under high load conditions. In the relationship curve between friction coefficient and loading force, in the low load range (5-20N), the friction coefficient of the okra hydrogel lubricant is slightly lower than that of the polyacrylamide hydrogel; in the high load range (>40N), the friction coefficient of the okra hydrogel lubricant is significantly lower than that of the polyacrylamide hydrogel, and the okra hydrogel lubricant can achieve a super lubrication effect (friction coefficient μ<0.01). BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The viscosity of Example 2 measured by the rheometer in steady-state mode and oscillatory mode: (a) the functional relationship between the shear viscosity η and the shear stress τ and the shear rate γ in the steady-state mode; (b) the functional relationship between the shear viscosity η and time in the steady-state mode; (c) the complex viscosity |η in the oscillatory mode * | as a function of frequency; (d) complex viscosity |η in oscillation mode * |As a function of time; Figure 2The SFA adsorption and force measurements of two hydrophilic mica surfaces in Example 2: (a) force / curvature radius-distance relationship diagrams at different time intervals of 20, 40, 60, and 120 minutes during the approach process and (b) the distance process; (c) schematic diagram of the approach process of the two mica surfaces; (d) schematic diagram of the distance process of the two mica surfaces; Figure 3 AFM images of Example 2 adsorbed on the hydrophilic mica surface: 3D AFM morphology of the newly cut mica surface after immersion in Example 2 for (a) 0 min, (b) 20 min, (c) 40 min, and (d) 120 min; (e) 2D AFM morphology of Example 2 adsorbed on the mica surface at 5µm×5µm; (f) cross-sectional height distribution diagram of the area shown in (e); Figure 4 SFA friction force measurement on hydrophilic mica surface in Example 2: (a) Friction force (f) at constant shear rate (ν = 0.13 μm / s) versus loading force (F ⊥ ) as a function of (b) f at a fixed load (F ⊥ =4.8mN) as a function of ν; Figure 5 SFA friction force measurement and AFM morphology imaging of the mica surface modified by octadecyltrichlorosilane (OTS) in Example 2: (a) f and F at a constant shear rate (ν = 0.13 μm / s) ⊥ Functional relationship of f at fixed loading force (F ⊥ =4.8mN) as a function of ν; (c) AFM morphology of the surface of OTS-modified mica after washing and air-drying after adsorption for 120min in Example 2, with a scanning area of ​​5µm×5µm; (d) an enlarged scan of the rectangular area shown in (c) (1µm×1µm); (e) a cross-sectional height distribution diagram of the blue line shown in (c); (f) a three-dimensional AFM morphology image of (c); Figure 6 (a) ATR-FTIR absorption spectrum of okra mucus powder obtained in Example 2; (b) schematic diagram of lubrication mechanism of okra lubricant adsorbed on substrate surface and confined shear layer between two adsorption layers; (c) enlarged schematic diagram of shear layer where polysaccharide polymer is hydrated during sliding; Figure 7 This is a comparative study of Example 5 and the comparative example: (a) schematic diagram of the dispersion of okra polysaccharide in the hydrogel network and solution; the functional relationship between the friction coefficient of Example 5 and the comparative example and (b) time, (c) angular velocity and (d) normal force. DETAILED DESCRIPTION

[0030] The present invention is described in detail below through specific examples and comparative examples, but the use and purpose of these exemplary implementation modes are only used to illustrate the present invention, and do not constitute any form of limitation on the actual protection scope of the present invention, nor limit the protection scope of the present invention to these.

[0031] The experimental methods described in the following examples and comparative examples are conventional methods unless otherwise specified; the reagents and materials described can be obtained from commercial sources.

[0032] Example 1 A kind of preparation method of okra lubricant (1) The okra that had been seeded and sliced ​​in advance was soaked in 10% by weight deionized water under stirring at room temperature for 24 h, filtered through pasteurized cheese cloth, and centrifuged at 7200 rpm for 20 min to obtain a raw okra mucus solution.

[0033] (2) Add 5 times the volume of acetone to the raw okra mucus solution, dissolve the precipitated white flocs in ethanol, and precipitate them again in acetone. Repeat the purification three times, wash with acetone, dry at room temperature, and grind to obtain okra mucus powder.

[0034] (3) Add 50 mg of okra mucus powder into 10 mL of NaCl solution (salt concentration is 1 mM) and stir to dissolve for 10 min to obtain okra lubricant.

[0035] Example 2 A method for preparing an okra lubricant comprises the following steps: (1) The okra that had been seeded and sliced ​​in advance was soaked in 20% by weight deionized water for 24 h under stirring at room temperature, filtered through pasteurized cheese cloth, and centrifuged at 7200 rpm for 20 min to obtain the raw okra mucus solution.

[0036] (2) Add 5 times the volume of acetone to the raw okra mucus solution, dissolve the precipitated white flocs in ethanol, and precipitate them again in acetone. Repeat the purification three times, wash with acetone, dry at room temperature, and grind to obtain okra mucus powder.

[0037] (3) Add 50 mg of okra mucus powder into 10 mL of NaCl solution (salt concentration is 1 mM) and stir to dissolve for 10 min to obtain okra lubricant.

[0038] Example 3 A method for preparing an okra lubricant comprises the following steps: (1) The okra that had been seeded and sliced ​​in advance was soaked in 30% by weight deionized water for 24 h under stirring at room temperature, filtered through pasteurized cheese cloth, and centrifuged at 7200 rpm for 20 min to obtain the raw okra mucus solution.

[0039] (2) Add 5 times the volume of acetone to the raw okra mucus solution, dissolve the precipitated white flocs in ethanol, and precipitate them again in acetone. Repeat the purification three times, wash with acetone, dry at room temperature, and grind to obtain okra mucus powder.

[0040] (3) Add 50 mg of okra mucus powder into 10 mL of NaCl solution (salt concentration is 1 mM) and stir to dissolve for 10 min to obtain okra lubricant.

[0041] Example 4 A method for preparing an okra lubricant comprises the following steps: (1) The okra that had been seeded and sliced ​​in advance was soaked in 40% by weight deionized water under stirring at room temperature for 24 hours, filtered through pasteurized cheese cloth, and centrifuged at 7200 rpm for 20 minutes to obtain the raw okra mucus solution.

[0042] (2) Add 5 times the volume of acetone to the raw okra mucus solution, dissolve the precipitated white flocs in ethanol, and precipitate them again in acetone. Repeat the purification three times, wash with acetone, dry at room temperature, and grind to obtain okra mucus powder.

[0043] (3) Add 50 mg of okra mucus powder into 10 mL of NaCl solution (salt concentration is 1 mM) and stir to dissolve for 10 min to obtain okra lubricant.

[0044] Example 5 A method for preparing an okra hydrogel lubricant comprises the following steps: (1) The okra that had been seeded and sliced ​​in advance was soaked in 20% by weight deionized water under stirring at room temperature for 24 h, filtered through pasteurized cheese cloth, and centrifuged at 7200 rpm for 20 min to obtain the raw okra mucus solution.

[0045] (2) Add 5 times the volume of acetone to the raw okra mucus solution, dissolve the precipitated white flocs in ethanol, and precipitate them again in acetone. Repeat the purification three times, wash with acetone, dry at room temperature, and grind to obtain okra mucus powder.

[0046] (3) Add 5 mg of okra mucus powder into 10 mL of NaCl solution (salt concentration is 1 mM) and stir to dissolve for 10 min to obtain okra lubricant.

[0047] (4) Dissolve 10 g of acrylamide, 0.15 g of photoinitiator and 0.15 g of N,N-methylenebisacrylamide in 30 g of okra lubricant prepared in step (3) to obtain an okra hydrogel precursor solution. Stir the precursor solution for 20 min, ultrasonically degas for 10 min, and ultraviolet cure for 30 min to obtain the okra hydrogel lubricant.

[0048] Comparative Example 1 A method for preparing a polyacrylamide hydrogel comprises the following steps: 10 g of acrylamide, 0.15 g of photoinitiator and 0.15 g of N,N-methylenebisacrylamide were dissolved in 30 g of deionized water to obtain a polyacrylamide hydrogel precursor solution. The precursor solution was stirred for 20 min, ultrasonically degassed for 10 min, and UV-cured for 30 min to obtain a polyacrylamide hydrogel.

[0049] Test Example 1 Rheological Measurement of Okra Lubricant The volume rheological behavior of the okra lubricant obtained in Example 2 at room temperature (25°C) was characterized using a rheometer (MCR 302, Anton Paar, Austria). The cone plate used in the experiment was a 1° cone plate with a diameter of 25 mm, and the gap between the cone and the plate was 0.101 mm; the oscillation experiment used a strain of 1%.

[0050] like Figure 1 As shown in (a), as the shear rate increases, the viscosity of the okra lubricant obtained in Example 2 decreases, indicating that the okra lubricant obtained in Example 2 is a non-Newtonian fluid and exhibits shear thinning characteristics; Figure 1 (b) shows that the shear rate is constant for 30 s -1 Under the conditions of , the viscosity of the okra lubricant obtained in Example 2 remained constant within 100s, indicating that the okra lubricant obtained in Example 2 has good stability; Figure 1 As shown in (c), as the frequency increases, the complex viscosity of the okra lubricant obtained in Example 2 first decreases and then increases, which is mainly due to the change in the aggregation state of the polysaccharide and mucin with the frequency; Figure 1 As shown in (d), under the condition of a constant frequency of 60 Hz, the complex viscosity of the okra lubricant obtained in Example 2 remained constant within 100 s, indicating that the okra lubricant obtained in Example 2 has good stability.

[0051] Test Example 2 Adsorption of okra lubricant on hydrophilic mica surface and measurement of its force The okra lubricant obtained in Example 2 was filtered through a syringe filter with a pore size of about 0.22 μm and set aside. Two silicon wafers with atomically smooth freshly cut mica (water contact angle of about 0°) were mounted in the SFA 2000 (SurForce LLC, Santa Barbara, CA USA) chamber in the form of crossed cylinders. When the distance D between the mica surfaces was much smaller than its radius of curvature R, the filtered okra lubricant was injected between the two mica surfaces, and the relationship between force / radius of curvature and distance was measured.

[0052] like Figure 2 As shown in (a) and (c), when the two mica surfaces approach each other, when the adsorption time is 20 minutes, repulsion occurs at 18nm. When the adsorption time reaches 120 minutes, the repulsion range expands to 45nm. Figure 2 As shown in (b) and (d), when the two mica surfaces are moving away from each other, repulsion is shown when the adsorption time is 20, 40, 60, and 120 minutes, and under the condition of the same adsorption time, the repulsion range when moving away is smaller than the repulsion range when approaching. The slight hysteresis repulsion and non-adhesion situation indicate that the okra lubricant obtained in Example 2 can be used for interface lubrication.

[0053] Test Example 3 AFM imaging of okra lubricant on hydrophilic mica surface The okra lubricant obtained in Example 2 was filtered through a syringe filter with a pore size of about 0.22 μm and set aside. The coating morphology formed on the hydrophilic mica surface in Example 2 was characterized using an atomic force microscope (Bruker Icon, CA, USA) in PeakForce tapping mode. The nominal resonance frequency of the silicon cantilever (Bruker Nano, USA) is 300-400 kHz, and the spring constant is about 42 N / m. The method for forming a coating on the hydrophilic mica surface by the filtered okra lubricant is as follows: 5 drops of the filtered okra lubricant are dropped onto 3 mica surfaces respectively, waiting for different time intervals (20, 40 and 120 min), then rinsing the coating surface with ultrapure water, and drying with nitrogen.

[0054] like Figure 3 As shown in (a)-(d), with the increase of adsorption time, the root mean square roughness of the coating formed by okra lubricant on the mica surface gradually increases to 0.6nm; Figure 3 As shown in (e) and (f), when the adsorption time is 120 min, the maximum cross-sectional height of the coating formed by the okra lubricant on the mica surface is 15 nm, while the height variation of the smooth area is less than 2 nm.

[0055] Test Example 4 Friction measurement of okra lubricant on hydrophilic mica surface Two silicon wafers with newly cut mica bonded with atomic smoothness were mounted in the SFA2000 chamber in the form of crossed cylinders. When the distance D between the mica was much smaller than its radius of curvature R, the okra lubricant obtained in Example 2 was injected between the two mica surfaces, and the relationship between the friction force, loading force and shear rate was measured.

[0056] like Figure 4 As shown in (a), the friction force of the coating formed by the okra lubricant obtained in Example 2 on the hydrophilic mica surface is linearly related to the loading force, and the friction coefficient μ is 0.12; Figure 4 As shown in (b), with the increase of shear rate, the friction force of the coating formed on the hydrophilic mica surface in Example 5 shows an upward trend, which is mainly due to the disentanglement and extension of the polysaccharide and protein macromolecular chains, the hydrodynamic effect and the confinement effect.

[0057] Test Example 5 Testing of okra lubricant on hydrophobic OTS-modified mica surface Preparation of hydrophobic OTS-modified mica: First, the freshly cut mica was treated with UV-ozone for 15 min, then quickly immersed in OTS-anhydrous toluene solution (volume ratio of 0.5%) for 10 min, washed with anhydrous toluene, dried with nitrogen, and annealed in air at 60°C for 4 h to obtain OTS-modified mica (contact angle of about 89°).

[0058] The same operation as in Test Examples 2, 3, and 4 was performed on the hydrophobic OTS-modified mica.

[0059] like Figure 5 As shown in (a), the friction force of the coating formed by the okra lubricant obtained in Example 2 on the hydrophobic mica surface is linearly related to the loading force, and the friction coefficient μ is 0.07. Compared with the coating on the hydrophilic mica surface, the friction force is significantly reduced; Figure 5 As shown in (b), as the shear rate increases, the friction force of the coating formed by the okra lubricant obtained in Example 2 on the hydrophilic mica surface shows an upward trend and the slope gradually decreases, and at the same shear rate, it is less than the friction force of the coating on the hydrophilic mica surface; Figure 5 As shown in (c)-(f), compared with the hydrophilic mica surface coating, the root mean square roughness of the hydrophobic mica surface coating is significantly increased, indicating that the adsorption behavior of the okra lubricant obtained in Example 2 on the hydrophobic surface is more obvious.

[0060] Test Example 6 Attenuated total reflection Fourier transform infrared testing of okra mucus powder The functional groups of the okra mucus powder obtained in Example 2 were confirmed using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR, Nicolet iS50, ThermoFisher Scientific).

[0061] like Figure 6 As shown in (a), the presence of characteristic peaks indicates that the okra mucus powder obtained in Example 2 is mainly composed of water-soluble polysaccharide complexes (galacturonic acid, neutral galactose, rhamnose and glucose, and a small amount of fructose, methyl pentose and xylose), plant protein and minerals; Figure 6 As shown in (b) and (c), the lubricating efficiency of okra lubricant is related to the dissolution and self-assembly of polysaccharides and proteins in the matrix. These hydrophilic groups can interact with water molecules to form a stable and lubricating hydration layer, thereby achieving the purpose of lubrication and anti-wear.

[0062] Test Example 7 Lubrication Testing of Okra Hydrogel Lubricant The volume rheological behaviors of the okra hydrogel lubricant of Example 5 and the polyacrylamide hydrogel of Comparative Example 1 at room temperature (25° C.) were characterized using a rheometer.

[0063] like Figure 7 As shown in (a), the polysaccharide of Example 5 is dispersed in the hydrogel precursor and then solidified to form a hydrogel matrix. Non-covalent interactions such as hydrogen bonds, electrostatic interactions and van der Waals forces stabilize the polysaccharide in the network. Figure 7 As shown in (b), during the test, the friction coefficient of Example 5 is always one fifth of that of Comparative Example 1; Figure 7 As shown in (c), at different angular velocities, the friction coefficient of Example 5 is lower than that of Comparative Example 1; Figure 7 As shown in (d), in the low normal force range of 5-20N, the friction coefficients of Example 5 and Comparative Example 1 are comparable. In the high normal force range of greater than 40N, the friction coefficient of Example 5 is less than that of Comparative Example 1 and is less than 0.01, exhibiting superlubricity.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an okra lubricant, characterized in that: The preparation method comprises the following steps: (1) The okra that has been seeded and sliced ​​in advance is soaked in deionized water under stirring at room temperature, and then filtered through pasteurized cheese cloth and centrifuged to obtain a raw okra mucus solution; (2) adding acetone to the raw okra mucus solution, dissolving the precipitated white flocs in ethanol, and precipitating them again in acetone. Repeating the purification three times, washing, drying, and grinding to obtain okra mucus powder; (3) Add okra mucus powder into NaCl solution and stir to dissolve to obtain okra lubricant.

2. The preparation method according to claim 1, characterized in that: In the step (1), the weight percentage of deionized water is 10%-40%, preferably, the weight percentage of deionized water is 20%; the soaking time is 24 hours; the centrifugal speed is 7200rpm, and the centrifugal time is 20 minutes; in the step (2), the volume of acetone is 5 times that of the raw okra mucus solution; the washing solvent is acetone; the drying condition is room temperature air; the salt concentration of the NaCl solution in the step (3) is 1mM; the mass concentration of the okra mucus powder is 0.5-5mg / mL, preferably 5mg / mL; the stirring and dissolving temperature is room temperature; and the stirring and dissolving time is 5-20min, preferably 10min.

3. the okra lubricant obtained by the preparation method as claimed in claim 1 or 2.

4. An okra hydrogel lubricant, characterized in that: The invention comprises the following raw materials: acrylamide (AM), a photoinitiator, N,N-methylenebisacrylamide (BAM) and the okra lubricant as claimed in claim 3.

5. The okra hydrogel lubricant according to claim 4, characterized in that: The mass of the photoinitiator is 1.5% of the mass of acrylamide. The photoinitiator is photoinitiator 2959, and its Chinese name is 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone.

6. The okra hydrogel lubricant according to claim 4, characterized in that: The mass of N,N-methylenebisacrylamide is 1.5% of the mass of acrylamide; the mass ratio of okra lubricant to acrylamide is 3:

1.

7. The method for preparing the okra hydrogel lubricant according to any one of claims 4 to 6, characterized in that: The following steps are involved: ① dissolving acrylamide, photoinitiator and N,N-methylenebisacrylamide in okra lubricant to obtain okra hydrogel precursor solution; ② The precursor solution is stirred, ultrasonically degassed, and then UV-cured to obtain the okra hydrogel lubricant.

8. The method for preparing the okra hydrogel lubricant according to claim 7, characterized in that: The stirring time in step ② is 15-30 min, preferably 20 min; the ultrasonic degassing time in step ② is 5-20 min, preferably 10 min; the UV curing time in step ② is 20-40 min, preferably 30 min.

9. Application of the okra hydrogel lubricant as described in any one of claims 4 to 6 in adsorption on model surfaces, exploration of lubrication mechanisms and hydration lubricant additives.

10. Application of the okra hydrogel lubricant obtained by the preparation method according to claim 7 or 8 in adsorption on model surfaces, exploration of lubrication mechanisms and hydration lubricating additives.

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