An okra lubricant, its preparation method and application

Abstract

This invention provides an okra lubricant, its preparation method, and its application. The okra lubricant is obtained by mixing okra mucilage powder with NaCl solution. The okra mucilage powder is prepared by soaking and contains water-soluble polysaccharide complexes, plant proteins, and minerals. It is then mixed with acrylamide, N,N-methylenebisacrylamide, and a photoinitiator, stirred, ultrasonically degassed, and then cured under ultraviolet light to obtain an okra hydrogel lubricant. The okra lubricant and okra hydrogel lubricant prepared by this invention possess good stability, adsorption, lubricity, and anti-wear properties while ensuring good biocompatibility. Furthermore, the preparation method is simple and low-cost, and it exhibits super-lubricating properties (friction coefficient μ<0.01) under high loads, meeting the low-friction requirements of practical applications.

Description

Technical Field

[0001] This invention relates to an okra lubricant, its preparation method and application, belonging to the field of natural plant extracts and hydrogels. Background Technology

[0002] Lubricants (such as engine oil and lubricating oil) are commonly used in machining, automobiles, and for the protection of cartilage joints from wear. Compared to traditional mineral oil-based lubricants, bio-lubricants have attracted much attention due to their excellent biodegradability, renewability, non-toxicity, and priority in 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 fluids and its preparation method. Through epoxidation modification of palm oil and the selection of optimized compound additives, the oxidative stability of palm oil is improved, viscosity is reduced, and the hydrolysis reaction of palm oil molecules is decreased, giving it good temperature resistance and lubrication properties, suitable for drilling operations where high-temperature resistance and lubrication performance are required. In addition, there is also a large amount of research on bio-water-based lubricants extracted from natural plants, which generally possess characteristics such as environmental friendliness, flame retardancy, high fluidity, and thermal conductivity. For example, Chinese patent document CN107376034A discloses a plant-based polypeptide water-soluble lubricant and its preparation method. The lubricant is prepared by uniformly mixing plant polypeptides, glycerol, polyethylene glycol, carbomer, petrolatum, phenoxyethanol, and water. This invention achieves the technical effects of being non-toxic, harmless, colorless, odorless, non-greasy, easy to clean, safe and hygienic, non-irritating and non-allergenic to the human body, and providing superior lubrication through the systematic combination of its components. Currently, lubricant production is costly, complex, and time-consuming, and may involve substances harmful to human health and the environment. In some cases, the lubrication effect may not meet practical requirements.

[0003] Okra is a fast-growing annual herb widely distributed in tropical regions. Rich in fiber, antioxidants, and minerals, okra is a well-known culinary food. Previous studies have shown that okra mucilage, extracted from the okra plant, can be used to treat wounds, ulcers, and inflammation, or as a medicine with analgesic effects on diabetes, dysentery, and spasms. Furthermore, the chemical composition of okra mucilage has been studied, revealing that its main components are water-soluble polysaccharide complexes, minerals, and plant proteins. Similar to Brassica oleracea, the smooth surface of okra in aqueous solution and its smooth texture upon tasting suggest that okra mucilage can also act as a biological lubricant. Previous studies have shown that adding 2 wt% of natural okra polysaccharides to aqueous lubricant formulations can reduce friction-induced surface deformation, thereby reducing the coefficient of friction and wear loss by 50%. Another study applied okra mucilage as an environmentally friendly, non-toxic shale swelling inhibitor to water-based drilling fluids, reducing clay swelling rates by 28.5% to 50.5% at concentrations ranging from 5% to 20%. Studies have shown that okra mucilage can improve rheological properties, reduce fluid loss, and provide lubrication, making it a green alternative to traditional clay stabilizers.

[0004] In current methods for extracting effective substances from okra, the pretreatment process commonly employs destructive operations such as crushing and pulping, as illustrated in Chinese patent documents CN109422822A and CN109453213A. This leaves ineffective substances from the okra in the final product, complicating the impurity removal process and potentially affecting subsequent use. While the lubricating properties of okra extract have been reported in existing technologies, and many inventions use it as an additive to enhance lubrication, none have used it as the primary component of a lubricant. Using okra extract as the primary component in a lubricant would ensure good biocompatibility. Hydrogels are soft materials with extremely high water content and have the potential to be used as biological lubricants. For example, Chinese patent document CN116874914A discloses a composite material and preparation method based on a soft / hard dual-network lubricant. Ultra-high molecular weight polyethylene is used as the continuous phase, and DN hydrogel microparticles, which are dispersed phases, are uniformly distributed in the interior of the continuous phase in a lattice structure. The DN hydrogel microspheres include a PAAm soft network and a UF hard network. However, the prior art has not introduced okra into hydrogel lubricants, nor has there been any invention of super-lubricating hydrogels containing okra extract. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an okra lubricant, its preparation method, and its applications. The okra hydrogel lubricant provided by this invention has a simple preparation method, low cost, good biocompatibility, and exhibits superlubricating properties under high loads, meeting the requirements for low friction in practical applications.

[0006] The technical solution of the present invention is as follows:

[0007] A method for preparing an okra lubricant includes the following steps:

[0008] (1) Okra that has been deseeded and sliced ​​in advance is soaked in deionized water under stirring at room temperature, and then filtered through pasteurized cheesecloth and centrifuged to obtain raw okra mucilage solution.

[0009] (2) Add acetone to the raw okra mucilage solution, dissolve the white flocculent substance obtained by precipitation in ethanol, precipitate it again in acetone, repeat the purification three times, wash, dry and grind to obtain okra mucilage powder.

[0010] (3) Add okra mucilage powder to NaCl solution and stir to dissolve to obtain okra lubricant.

[0011] According to a preferred embodiment of 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%; the soaking time is 24h.

[0012] According to a preferred embodiment of the present invention, in step (1), the centrifugation rate is 7200 rpm and the centrifugation time is 20 min.

[0013] According to a preferred embodiment of the present invention, in step (2), the volume of acetone is 5 times that of the raw okra mucilage solution.

[0014] According to a preferred embodiment of the present invention, in step (2), the solvent used for washing is acetone; and the drying conditions are room temperature air.

[0015] According to a preferred embodiment of the present invention, the salt concentration of the NaCl solution in step (3) is 1 mM.

[0016] According to a preferred embodiment of the present invention, the mass concentration of okra mucilage powder in step (3) is 0.5-5 mg / mL, and more preferably 5 mg / mL.

[0017] According to a preferred embodiment of 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.

[0018] The present invention also provides an okra hydrogel lubricant, comprising the following raw materials: acrylamide (AM), photoinitiator, N,N-methylenebisacrylamide (BAM) and okra lubricant.

[0019] According to a preferred embodiment of the present invention, the photoinitiator is photoinitiator 2959, whose Chinese name is 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone.

[0020] According to a preferred embodiment of 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 okra lubricant to acrylamide is 3:1.

[0021] The preparation method of the above-mentioned okra hydrogel lubricant includes the following steps:

[0022] ① Acrylamide, photoinitiator and N,N-methylenebisacrylamide were dissolved in okra lubricant to obtain okra hydrogel precursor solution;

[0023] ②The precursor solution was stirred, ultrasonically degassed, and then UV cured to obtain okra hydrogel lubricant.

[0024] According to a preferred embodiment of the present invention, the stirring time in step ② is 15-30 min, and more preferably 20 min.

[0025] According to a preferred embodiment of the present invention, the ultrasonic degassing time in step ② is 5-20 min, and more preferably 10 min.

[0026] According to a preferred embodiment of the present invention, the UV curing time in step ② is 20-40 min, and more preferably 30 min.

[0027] This invention also provides an exploration of the adsorption and lubrication mechanism of the above-mentioned okra mucilage water-based lubricant on the model surface and its application in hydration lubricant additives.

[0028] The okra mucilage powder of this invention is a white powder that is easy to store for a long time. It mainly contains a water-soluble polysaccharide complex (composed of galacturonic acid, neutral galactose, rhamnose and glucose, with small amounts of fructose, methylpentose and xylose), plant protein and minerals. The composition is clear and the purity is high, which facilitates subsequent impurity removal and purification operations.

[0029] The okra lubricant provided by this invention is a non-Newtonian fluid exhibiting shear-thinning behavior. Related viscosity experiments demonstrate its good stability, making it suitable for developing stable biological lubricants. The adsorption behavior of the okra lubricant on mica surfaces shows that it can slowly adsorb onto mica to form a relatively soft adsorbed layer. Furthermore, it exhibits strong spatial repulsion during the approach and departure of adsorbed layers. This slight hysteresis and lack of adhesion allow the okra lubricant to be used for interfacial lubrication. The adsorption behavior and adsorbed layer formation of the okra lubricant provided by this invention are influenced by intermolecular interactions and surface properties, thereby achieving the regulation of its lubricity and anti-wear properties.

[0030] The okra hydrogel lubricant provided by this invention exhibits super-lubricating properties under high loads. When the above-mentioned okra lubricant is added to a polyacrylamide hydrogel, a lubricating film forms on the surface of the okra hydrogel lubricant due to the hydration of the polymer chains and polysaccharides. The polysaccharides diffused into the lubricating film can be adsorbed onto the substrate surface and form an additional hydration film, hindering direct contact between the substrate and the hydrogel surface, thereby significantly reducing the coefficient of friction.

[0031] Technical features and beneficial effects of the present invention:

[0032] (1) The okra extraction method provided by this invention adopts an soaking method, which is simple to prepare, environmentally friendly, and produces okra mucilage powder with high purity that can be stored for a long time. This method does not involve any destructive operations on the okra, but rather uses a soaking method. While extracting the effective substances from the okra, it greatly reduces the possibility of ineffective substances from the okra mixing into the okra mucilage powder, thus improving the purity of the okra mucilage powder and simplifying the subsequent purification process. The extraction process involves soaking, stirring, and extraction, and is carried out at room temperature and in an air environment, making it convenient to implement and requiring less equipment, thus having industrial application value. Deionized water, ethanol, and acetone are used as solvents during the extraction process, which are easy to recycle and are environmentally friendly.

[0033] (2) The okra lubricant provided by this invention uses okra mucilage powder as the main component, which, while possessing good stability, adsorption, lubricity, and anti-wear properties, ensures good biocompatibility. The okra lubricant provided by this invention comprises the above-mentioned okra mucilage powder and NaCl solution, and the preparation method is simple and can be industrially scaled up.

[0034] (3) The okra hydrogel lubricant provided by the present invention has good biocompatibility. 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 low in cost. Under the correct operation and handling conditions, the preparation process and related products will not have adverse effects on the human body and the environment, and have good biocompatibility.

[0035] (4) The okra hydrogel lubricant provided by the present invention has super-lubricating properties under high load. In the relationship curve between the coefficient of friction and the loading force, in the low load range (5-20N), the coefficient of friction of the okra hydrogel lubricant is slightly lower than that of the polyacrylamide hydrogel; in the high load range (>40N), the coefficient of friction of the okra hydrogel lubricant is significantly lower than that of the polyacrylamide hydrogel, and the okra hydrogel lubricant can achieve the effect of super-lubrication (coefficient of friction μ<0.01). Attached Figure Description

[0036] Figure 1 The following are examples of viscosity measurements from an rheometer in steady-state and oscillating modes for Example 2: (a) Shear viscosity η and shear stress τ as a function of shear rate γ in steady-state mode; (b) Shear viscosity η as a function of time in steady-state mode; (c) Complex viscosity |η| in oscillating mode. * | Functional relationship with frequency; (d) Complex viscosity in oscillatory mode |η * | Functional relationship with time;

[0037] Figure 2 SFA adsorption and force measurements of two hydrophilic mica surfaces in Example 2: (a) Force / radius of curvature-distance relationship graphs at different time intervals of 20, 40, 60, and 120 minutes during the approach and (b) moving away processes, respectively; (c) Schematic diagram of the approach process of the two mica surfaces; (d) Schematic diagram of the moving away process of the two mica surfaces.

[0038] Figure 3 AFM images of mica adsorbed on the surface of hydrophilic mica in Example 2: 3D AFM morphology of the freshly cut mica surface after soaking in Example 2 for (a) 0 min, (b) 20 min, (c) 40 min, and (d) 120 min; (e) 2D AFM morphology of the mica surface adsorbed in Example 2 at a depth of 5 µm × 5 µm; (f) Cross-sectional height distribution of the area shown in (e).

[0039] Figure 4 SFA friction force measurement on hydrophilic mica surface for Example 2: (a) Friction force (f) at constant shear rate (ν = 0.13 μm / s) versus loading force (F) ⊥ (a) the functional relationship of f under a fixed loading force (F); (b) f under a fixed loading force (F) ⊥ The functional relationship between ν and ν at ν = 4.8mN;

[0040] Figure 5 Example 2: SFA friction measurement and AFM morphology imaging of octadecyltrichlorosilane (OTS) modified mica surface: (a) f at a constant shear rate (ν = 0.13 μm / s) with F ⊥ (b) f under a fixed loading force (F) ⊥ =4.8mN) Functional relationship with ν; (c) AFM morphology of OTS modified mica surface after water washing and air drying after 120 min of adsorption in Example 2, with a scanning area of ​​5µm×5µm; (d) Enlarged scan image of the rectangular area shown in (c) (1µm×1µm); (e) Cross-sectional height distribution map of the blue line shown in (c); (f) Three-dimensional AFM morphology image of (c);

[0041] Figure 6(a) ATR-FTIR absorption spectrum of okra mucilage powder obtained in Example 2; (b) schematic diagram of the lubrication mechanism of okra lubricant adsorbed on the substrate surface, and the confined shear layer between the two adsorption layers; (c) magnified schematic diagram of the shear layer of polysaccharide polymer being hydrated during sliding.

[0042] Figure 7 Comparative study of Example 5 and the comparative example: (a) Schematic diagram of okra polysaccharide dispersion in hydrogel network and solution; Functional relationship between the friction coefficient of Example 5 and the comparative example and (b) time, (c) angular velocity and (d) normal force. Detailed Implementation

[0043] The present invention will now be described in detail with reference to specific embodiments and comparative examples. However, the uses and purposes of these exemplary embodiments are only for illustrating the present invention and are not intended to limit the actual scope of protection of the present invention in any way, nor are they intended to limit the scope of protection of the present invention to these embodiments.

[0044] Unless otherwise specified, the experimental methods described in the following examples and comparative examples are conventional methods; the reagents and materials described are all commercially available.

[0045] Example 1

[0046] A method for preparing okra lubricant

[0047] (1) Okra that has been deseeded and sliced ​​in advance was soaked in 10% deionized water for 24 hours under stirring at room temperature. After filtration through pasteurized cheesecloth, it was centrifuged at 7200 rpm for 20 minutes to obtain raw okra mucilage solution.

[0048] (2) Add 5 times the volume of acetone to the raw okra mucilage solution, dissolve the white flocculent substance obtained by precipitation in ethanol, precipitate it again in acetone, repeat the purification three times, wash with acetone, dry at room temperature, and grind to obtain okra mucilage powder.

[0049] (3) Add 50 mg of okra mucilage powder to 10 mL of NaCl solution (salt concentration of 1 mM) and stir to dissolve for 10 min to obtain okra lubricant.

[0050] Example 2

[0051] A method for preparing an okra lubricant, comprising the following steps:

[0052] (1) Okra that has been deseeded and sliced ​​in advance was soaked in 20% deionized water for 24 hours under stirring at room temperature. After filtration through pasteurized cheesecloth, it was centrifuged at 7200 rpm for 20 minutes to obtain raw okra mucilage solution.

[0053] (2) Add 5 times the volume of acetone to the raw okra mucilage solution, dissolve the white flocculent substance obtained by precipitation in ethanol, precipitate it again in acetone, repeat the purification three times, wash with acetone, dry at room temperature, and grind to obtain okra mucilage powder.

[0054] (3) Add 50 mg of okra mucilage powder to 10 mL of NaCl solution (salt concentration of 1 mM) and stir to dissolve for 10 min to obtain okra lubricant.

[0055] Example 3

[0056] A method for preparing an okra lubricant, comprising the following steps:

[0057] (1) Okra that has been deseeded and sliced ​​in advance was soaked in 30% deionized water for 24 hours under stirring at room temperature. After filtration through pasteurized cheesecloth, it was centrifuged at 7200 rpm for 20 minutes to obtain raw okra mucilage solution.

[0058] (2) Add 5 times the volume of acetone to the raw okra mucilage solution, dissolve the white flocculent substance obtained by precipitation in ethanol, precipitate it again in acetone, repeat the purification three times, wash with acetone, dry at room temperature, and grind to obtain okra mucilage powder.

[0059] (3) Add 50 mg of okra mucilage powder to 10 mL of NaCl solution (salt concentration of 1 mM) and stir to dissolve for 10 min to obtain okra lubricant.

[0060] Example 4

[0061] A method for preparing an okra lubricant, comprising the following steps:

[0062] (1) Okra that has been deseeded and sliced ​​in advance was soaked in 40% deionized water for 24 hours under stirring at room temperature. After filtration through pasteurized cheesecloth, it was centrifuged at 7200 rpm for 20 minutes to obtain raw okra mucilage solution.

[0063] (2) Add 5 times the volume of acetone to the raw okra mucilage solution, dissolve the white flocculent substance obtained by precipitation in ethanol, precipitate it again in acetone, repeat the purification three times, wash with acetone, dry at room temperature, and grind to obtain okra mucilage powder.

[0064] (3) Add 50 mg of okra mucilage powder to 10 mL of NaCl solution (salt concentration of 1 mM) and stir to dissolve for 10 min to obtain okra lubricant.

[0065] Example 5

[0066] A method for preparing an okra hydrogel lubricant, comprising the following steps:

[0067] (1) Okra that has been deseeded and sliced ​​in advance was soaked in 20% deionized water for 24 hours under stirring at room temperature. After filtration through pasteurized cheesecloth, it was centrifuged at 7200 rpm for 20 minutes to obtain raw okra mucilage solution.

[0068] (2) Add 5 times the volume of acetone to the raw okra mucilage solution, dissolve the white flocculent substance obtained by precipitation in ethanol, precipitate it again in acetone, repeat the purification three times, wash with acetone, dry at room temperature, and grind to obtain okra mucilage powder.

[0069] (3) Add 5 mg of okra mucilage powder to 10 mL of NaCl solution (salt concentration of 1 mM) and stir to dissolve for 10 min to obtain okra lubricant.

[0070] (4) Dissolve 10g acrylamide, 0.15g photoinitiator and 0.15g N,N-methylenebisacrylamide in 30g okra lubricant prepared in step (3) to obtain okra hydrogel precursor solution. Stir the precursor solution for 20min, degas it by ultrasound for 10min and cure it by UV for 30min to obtain okra hydrogel lubricant.

[0071] Comparative Example 1

[0072] A method for preparing a polyacrylamide hydrogel, comprising the following steps:

[0073] 10g acrylamide, 0.15g photoinitiator and 0.15g N,N-methylenebisacrylamide were dissolved in 30g deionized water to obtain a polyacrylamide hydrogel precursor solution. The precursor solution was stirred for 20min, ultrasonically degassed for 10min and UV cured for 30min to obtain polyacrylamide hydrogel.

[0074] Experimental Example 1

[0075] Rheological measurements of okra lubricant

[0076] The volumetric 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 a gap of 0.101 mm between the cone and the plate; the oscillation experiment used a strain of 1%.

[0077] like Figure 1 As shown in (a), the viscosity of the okra lubricant obtained in Example 2 decreases with increasing shear rate, indicating that the okra lubricant obtained in Example 2 is a non-Newtonian fluid exhibiting shear-thinning properties; Figure 1 As shown in (b), when the shear rate is constant at 30 s... -1Under the specified conditions, the viscosity of the okra lubricant obtained in Example 2 remained constant within 100 seconds, indicating that the okra lubricant obtained in Example 2 has good stability; Figure 1 As shown in (c), the complex viscosity of the okra lubricant obtained in Example 2 first decreased and then increased with increasing frequency. This is mainly due to the change in the aggregation state of polysaccharides and mucins with 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.

[0078] Experimental Example 2

[0079] Adsorption and force measurement of okra lubricant on hydrophilic mica surface

[0080] The okra lubricant obtained in Example 2 was filtered through a needle filter with a pore size of approximately 0.22 μm and set aside for later use. Two silicon wafers with newly cut mica (water contact angle approximately 0°) with atomic smoothness were mounted in a cross-cylinder configuration in an SFA 2000 (SurForce LLC, Santa Barbara, CA USA) chamber. When the distance D between the mica 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.

[0081] like Figure 2 As shown in (a) and (c), during the process of the two mica surfaces approaching each other, when the adsorption time is 20 min, a repulsive force is observed at 18 nm; when the adsorption time reaches 120 min, the repulsive force range expands to 45 nm. Figure 2 As shown in (b) and (d), during the process of the two mica surfaces moving away from each other, repulsive forces were observed at adsorption times of 20, 40, 60, and 120 min. Furthermore, under the same adsorption time conditions, the range of repulsive forces when moving away was smaller than that when moving closer. The slight hysteresis of the repulsive force and the absence of adhesion indicate that the okra lubricant obtained in Example 2 can be used for interfacial lubrication.

[0082] Experimental Example 3

[0083] AFM imaging of okra lubricant on hydrophilic mica surface

[0084] The okra lubricant obtained in Example 2 was filtered through a needle filter with a pore size of approximately 0.22 μm and set aside for later use. The morphology of the coating formed on the hydrophilic mica surface in Example 2 was characterized using atomic force microscopy (Bruker Icon, CA, USA) in PeakForce tapping mode. The nominal resonant frequency of the silicon cantilever beam (Bruker Nano, USA) was 300-400 kHz, and the spring constant was approximately 42 N / m. The method for forming a coating on the hydrophilic mica surface with the filtered okra lubricant was as follows: 5 drops of the filtered okra lubricant were dropped onto 3 mica surfaces, and different time intervals (20, 40, and 120 min) were allowed. The coating surface was then rinsed with ultrapure water and dried with nitrogen.

[0085] like Figure 3 As shown in (a)-(d), with increasing adsorption time, the root mean square roughness of the coating formed by okra lubricant on the mica surface gradually increases to 0.6 nm; 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 okra lubricant on the mica surface is 15 nm, while the height variation of the smooth area is less than 2 nm.

[0086] Test Example 4

[0087] Frictional force measurement of okra lubricant on hydrophilic mica surface

[0088] Two silicon wafers with newly cut mica with atomic smoothness were mounted in an SFA2000 chamber in the form of intersecting 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 frictional force and loading force and shear rate was measured.

[0089] like Figure 4 As shown in (a), the frictional force of the coating formed by the okra lubricant obtained in Example 2 on the surface of hydrophilic mica is linearly related to the applied force, and the coefficient of friction μ is 0.12; Figure 4 As shown in (b), the friction of the coating formed on the hydrophilic mica surface in Example 5 increases with the increase of shear rate. This is mainly due to the unentanglement and extension of polysaccharide and protein macromolecular chains, hydrodynamic effects and confinement effects.

[0090] Experimental Example 5

[0091] Testing of okra lubricant on hydrophobic OTS-modified mica surfaces

[0092] Preparation of hydrophobic OTS modified mica: First, freshly cut mica was treated with ultraviolet 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℃ for 4 h to obtain OTS modified mica (contact angle of approximately 89°).

[0093] The hydrophobic OTS-modified mica was subjected to the same procedures as in Experimental Examples 2, 3, and 4.

[0094] like Figure 5 As shown in (a), the friction force of the coating formed by the okra lubricant on the hydrophobic mica surface in Example 2 is linearly related to the applied force, with a friction coefficient μ of 0.07. Compared to the coating on the hydrophilic mica surface, the friction force is significantly reduced. Figure 5 As shown in (b), with the increase of shear rate, the frictional force of the coating formed on the hydrophilic mica surface by the okra lubricant obtained in Example 2 shows an increasing trend and the slope gradually decreases, and at the same shear rate, it is less than the frictional force of the coating on the hydrophilic mica surface; Figure 5 As shown in (c)-(f), the root mean square roughness of the hydrophobic mica surface coating is significantly increased compared to the hydrophilic mica surface coating, indicating that the okra lubricant obtained in Example 2 exhibits more pronounced adsorption behavior on the hydrophobic surface.

[0095] Experimental Example 6

[0096] Attenuation total internal reflection Fourier transform infrared test of okra mucilage powder

[0097] The functional groups of the okra mucilage powder obtained in Example 2 were identified using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR, Nicolet iS50, ThermoFisher Scientific).

[0098] like Figure 6 As shown in (a), the presence of characteristic peaks indicates that the okra mucilage powder obtained in Example 2 is mainly composed of a water-soluble polysaccharide complex (galacturonic acid, neutral galactose, rhamnose, and glucose, with small amounts of fructose, methylpentose, and xylose), plant protein, and minerals; Figure 6 As shown in (b) and (c), the lubrication efficiency of okra lubricant is related to the dissolution and self-assembly of polysaccharides and proteins on the matrix. These hydrophilic groups can interact with water molecules to form a stable lubricating hydration layer, thereby achieving the purpose of lubrication and anti-wear.

[0099] Experimental Example 7

[0100] Lubrication test of okra hydrogel lubricant

[0101] The volumetric rheological behavior of the okra hydrogel lubricant of Example 5 and the polyacrylamide hydrogel of Comparative Example 1 at room temperature (25°C) was characterized using a rheometer.

[0102] like Figure 7 As shown in (a), the polysaccharide in Example 5 was dispersed in a hydrogel precursor, which was subsequently solidified to form a hydrogel matrix. Non-covalent interactions, such as hydrogen bonds, electrostatic interactions, and van der Waals forces, stabilized the polysaccharide within the network. Figure 7 As shown in (b), during the test, the coefficient of friction of Example 5 was consistently one-fifth that of Comparative Example 1; Figure 7 As shown in (c), at different angular velocities, the coefficient of friction in Example 5 is lower than that in 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 super-lubricating properties.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions 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. The application of an okra hydrogel lubricant in improving the lubrication properties of mica surfaces or as a hydration lubricant additive, characterized in that, The okra hydrogel lubricant comprises the following raw materials: acrylamide (AM), photoinitiator, N,N-methylenebisacrylamide (BAM), and okra lubricant; The preparation method of the okra lubricant includes the following steps: (1) Okra that has been deseeded and sliced ​​in advance is soaked in deionized water under stirring at room temperature, and then filtered through pasteurized cheesecloth and centrifuged to obtain raw okra mucilage solution. (2) Add acetone to the raw okra mucilage solution, dissolve the white flocculent substance obtained by precipitation in ethanol, precipitate it again in acetone, repeat the purification three times, wash, dry and grind to obtain okra mucilage powder. (3) Add okra mucilage powder to NaCl solution, stir to dissolve, and obtain okra lubricant; The photoinitiator has a mass of 1.5% of the acrylamide mass, and the photoinitiator is photoinitiator 2959; 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. The preparation method of the okra hydrogel lubricant includes the following steps: Acrylamide, photoinitiator and N,N-methylenebisacrylamide were dissolved in okra lubricant to obtain okra hydrogel precursor solution; The precursor solution was stirred, ultrasonically degassed, and then cured under ultraviolet light to obtain okra hydrogel lubricant.

2. The application of the okra hydrogel lubricant according to claim 1 in improving the lubrication performance of mica surfaces or as a hydration lubricant additive, characterized in that, In step (1), the weight percentage of deionized water is 10%-40%; the soaking time is 24h; the centrifugation rate is 7200rpm and the centrifugation time is 20min; in step (2), the volume of acetone is 5 times that of the raw okra mucilage solution; the solvent used for washing is acetone; the drying condition is room temperature air; in step (3), the salt concentration of NaCl solution is 1mM; the mass concentration of okra mucilage powder is 0.5-5mg / mL; the stirring and dissolving temperature is room temperature; and the stirring and dissolving time is 5-20min.

3. The application of the okra hydrogel lubricant according to claim 2 in improving the lubrication performance of mica surfaces or as a hydration lubricant additive, characterized in that, In step (1), the weight percentage of deionized water is 20%.

4. The application of the okra hydrogel lubricant according to claim 2 in improving the lubrication performance of mica surfaces or as a hydration lubricant additive, characterized in that, In step (3), the mass concentration of okra mucilage powder is 5 mg / mL.

5. The application of the okra hydrogel lubricant according to claim 2 in improving the lubrication performance of mica surfaces or as a hydration lubricant additive, characterized in that, In step (3), the stirring and dissolving time is 10 min.

6. The application of the okra hydrogel lubricant according to claim 1 in improving the lubrication performance of mica surfaces or as a hydration lubricant additive, characterized in that, The steps The stirring time is 15-30 minutes; Step The ultrasonic degassing time is 5-20 minutes; steps The UV curing time is 20-40 minutes.

7. The application of the okra hydrogel lubricant according to claim 6 in improving the lubrication performance of mica surfaces or as a hydration lubricant additive, characterized in that, The steps The stirring time is 20 minutes.

8. The application of the okra hydrogel lubricant according to claim 6 in improving the lubrication performance of mica surfaces or as a hydration lubricant additive, characterized in that, step The ultrasonic degassing time is 10 minutes.

9. The application of the okra hydrogel lubricant according to claim 6 in improving the lubrication performance of mica surfaces or as a hydration lubricant additive, characterized in that, step The UV curing time is 30 minutes.

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