Oil gel with lubricating and anti-fouling functions and preparation method thereof

Abstract

The application discloses an oil gel with lubricating and antifouling functions and a preparation method thereof. The preparation method of the oil gel is as follows: isocyanate groups of isophorone diisocyanate are reacted with hydroxyl groups of polytetrahydrofuran to generate a polyurethane prepolymer, 4,4'-dithiodianiline is used as a chain extender to react to generate a polyurethane-polyurea skeleton, and nano-cellulose crystals, multi-walled carbon nanotubes and graphite oxide powder are added to introduce multiple hydrogen bonds to prepare the oil gel. The oil gel prepared by the application has excellent self-healing performance, photo-thermal conversion performance and low surface energy, a dynamic lubricating surface of the oil gel can realize good protein adhesion resistance, antibacterial adhesion resistance and algae adhesion resistance, and the oil gel can be used as a ship drag reduction and antifouling material.

Description

Technical Field

[0001] This invention belongs to the field of marine antifouling coating technology, and relates to an oil gel with lubricating and antifouling functions and its preparation method. Background Technology

[0002] Marine biofouling refers to the damage caused by marine organisms adhering to the surface of marine equipment. It poses serious threats to marine equipment and maritime vessels. A 10% biofouling rate can increase a ship's drag by approximately 30%, and in severe cases, it can increase drag by 93%. Globally, biofouling causes direct losses exceeding billions of dollars annually. Using suitable coatings is the simplest and most economical way to reduce marine biofouling. Self-polishing coatings containing tributyltin are highly effective against biofouling, but they cause persistent toxicity to marine organisms, impacting the marine environment and human health. In 2008, the International Maritime Organization banned their use as marine coatings. Copper / zinc-based coatings also pose an environmental threat. Therefore, developing non-toxic and highly effective marine antifouling coatings is crucial.

[0003] The low surface energy and non-toxic properties of polydimethylsiloxane make it a promising candidate for marine antifouling coatings. However, its inherent drawbacks significantly limit its large-scale promotion and practical application. The most prominent issues are poor adhesion and low mechanical strength. On the one hand, while the low surface energy of polydimethylsiloxane is beneficial for antifouling, it also results in weak adhesion to substrates such as ships and metals. The coating is prone to peeling and wrinkling, failing to maintain stable adhesion to the substrate surface for extended periods, thus affecting the durability of the antifouling effect. On the other hand, the high flexibility of the Si-O backbone in its molecular structure leads to low mechanical strength in the resulting coating, resulting in insufficient impact and wear resistance. When subjected to wave impacts and friction in the marine environment, it is prone to damage and cracking, ultimately losing its antifouling function. This increases maintenance costs and replacement frequency, hindering its further application and development in the field of marine antifouling.

[0004] Currently, most antifouling coatings use high molecular weight polydimethylsiloxane. Adhesion performance and mechanical strength are improved by grafting polymers with adhesive effects or high mechanical properties and adding fillers. However, these methods inevitably increase the surface free energy, reducing or even eliminating the antifouling effect. Summary of the Invention

[0005] The purpose of this invention is to provide an oil gel with lubricating and antifouling functions and its preparation method. The oil gel of this invention possesses excellent self-healing properties, photothermal conversion properties, and low surface energy, enabling it to achieve good anti-protein adhesion, antibacterial adhesion, and anti-algae adhesion. This invention proposes using low molecular weight polydimethylsiloxane as a filler, which avoids problems of poor adhesion and low mechanical strength. The oil gel is prepared using a polyurethane-polyurea framework. The polyurethane or polyurea fragments have urethane / urea bonds, which can form hydrogen bonds with the substrate, thus serving as a framework material to achieve high adhesion performance of the coating. Damage to the coating will directly cause it to lose its performance. This application introduces multiple hydrogen bonds and disulfide bonds to provide self-healing properties for the coating, extending its service life. Adding high-strength nanomaterials, such as nanocellulose crystals, to the coating can significantly improve its mechanical strength. Introducing graphite oxide powder and multi-walled carbon nanotubes into the coating, these two-dimensional materials with strong impermeability and a labyrinth effect, can provide anti-corrosion effects, and their photothermal conversion properties can increase the coating temperature, thus providing antibacterial effects. In addition, nanocellulose crystals, carbon nanotubes, and graphite oxide powder all have abundant -OH groups, which can form hydrogen bonds with the polyurethane-polyurea skeleton, acting as physical cross-linking points, filling internal defects in the coating, and further improving the mechanical properties and corrosion resistance of the coating.

[0006] The oil gel with lubricating and antifouling properties of the present invention is prepared by reacting the isocyanate groups of isophorone diisocyanate with the hydroxyl groups of polytetrahydrofuran to generate a polyurethane prepolymer, using 4,4'-dithiodiphenylamine as a chain extender to generate a polyurethane-polyurea skeleton, and finally adding dimethyl silicone oil containing dispersed nanocellulose crystals, multi-walled carbon nanotubes and graphite oxide powder to introduce multiple hydrogen bonds.

[0007] Specifically, the preparation method of an oil gel with lubricating and antifouling functions includes the following steps:

[0008] 1) Isophorone diisocyanate, polytetrahydrofuran, and the catalyst dibutyltin dilaurate were added to a three-necked flask and heated at 75-85°C for 3.5-5 h under nitrogen atmosphere to generate polyurethane prepolymer.

[0009] 2) 4,4'-dithiodiphenylamine was added to the polyurethane prepolymer as a chain extender and heated at 75~85℃ for 1.5~2.5 h under nitrogen atmosphere to generate a polyurethane-polyurea skeleton. Acetone was added during the reaction to reduce viscosity.

[0010] 3) Dimethyl silicone oil, silane coupling agent, nanocellulose crystals, graphite oxide powder and multi-walled carbon nanotubes in different proportions, and sodium lauryl are ultrasonically dispersed to obtain a mixed oil solution, which is then added to a polyurethane-polyurea skeleton. Acetone is added to reduce the viscosity, and the mixture is heated at 75~85℃ for 0.5~1.5h to generate an oil gel.

[0011] In the above technical solution, further, in step 1), the molar ratio of isophorone diisocyanate to polytetrahydrofuran is 2.2:0.8~1.2, and more preferably 2.2:1; the content of the catalyst dibutyltin dilaurate in the polyurethane-polyurea skeleton is 0.01wt%~0.5wt%, and more preferably 0.015wt%.

[0012] Further, in step 2), the amount of 4,4'-dithiodiphenylamine used is such that the molar ratio of isophorone diisocyanate to 4,4'-dithiodiphenylamine is 2.2:1~1.4, and more preferably the molar ratio is 2.2:1.2.

[0013] Furthermore, the content of the nanocellulose crystals in the oleogel in step 3) is 1wt%~5wt%, more preferably 3wt%. The nanocellulose crystals can form strong intermolecular hydrogen bonds with polyurethane-polyurea fragments, which can act as physical cross-linking points and enhance the overall mechanical properties of the oleogel.

[0014] Further, in step 3), the content of graphite oxide powder and multi-walled carbon nanotubes in the oleogel is 1wt%~5wt%, preferably 3wt%, wherein the mass ratio of graphite oxide powder to multi-walled carbon nanotubes is 1:1. The chemical inertness and labyrinth effect of graphite oxide powder and multi-walled carbon nanotubes can prevent the intrusion of corrosive media and enhance the anti-corrosion performance of the oleogel coating. At the same time, their photothermal conversion properties can increase the surface temperature of the oleogel, resulting in an antibacterial effect. Graphite oxide powder has good photothermal conversion properties but is expensive, while multi-walled carbon nanotubes are inexpensive and also have certain photothermal conversion properties. Moreover, their high aspect ratio can enhance the mechanical properties of the oleogel coating. The combined use of the two can impart good performance to the oleogel while better controlling the cost of the oleogel.

[0015] Furthermore, the sodium laurylate content in the oleogel described in step 3) is 0wt%~3wt%, and more preferably 3wt%. Sodium laurylate ionizes at around pH 8 in seawater, giving the surface of the oleogel coating a negative charge, increasing electrostatic repulsion, and reducing the adhesion of proteins and bacteria.

[0016] Further, in step 1), the heating temperature is 80℃ and the heating reaction time is 4 h; in step 2), the heating temperature is 80℃ and the heating reaction time is 2 h; in step 3), the heating temperature is 80℃ and the heating reaction time is 1 h.

[0017] The method of using the above-mentioned oleogel is as follows: apply the oleogel prepared in step 3) to the substrate surface, and cure it for 7 days to form an oleogel coating.

[0018] The beneficial effects of this invention are as follows:

[0019] 1. Currently, most antifouling coatings use high molecular weight polydimethylsiloxane as the filler. The poor adhesion and mechanical strength are improved by grafting polymers with good adhesion or high mechanical properties and adding fillers. However, these methods inevitably increase the surface free energy, reducing or even eliminating the antifouling effect. This invention proposes an oleogel prepared using low molecular weight polydimethylsiloxane as the filler and polyurethane-polyurea as the skeleton, avoiding the drawbacks while maintaining good antifouling performance.

[0020] 2. This invention uses 4,4'-dithiodiphenylamine as a chain extender. Disulfide bonds can provide self-healing properties for oleogels. Nanocellulose crystals, graphite oxide powder, and multi-walled carbon nanotubes form multiple hydrogen bonds with the polyurethane-polyurea framework, enhancing the self-healing properties of the oleogel.

[0021] 3. The oleogel prepared by this invention, with the addition of graphite oxide powder and multi-walled carbon nanotubes, can endow the oleogel with excellent photothermal conversion properties, increase the surface temperature of the oleogel to play a bactericidal role, and enhance the anti-corrosion function of the oleogel; the addition of sodium laurate reduces the surface energy of the oleogel and reduces the surface potential of the oleogel, preventing biological contamination through electrostatic repulsion.

[0022] 4. The oleogel prepared by this invention has excellent self-healing properties, photothermal conversion properties, and low surface energy. Its dynamic lubricating surface can achieve good anti-protein adhesion, antibacterial adhesion, and anti-algae adhesion, and can be used as a material for reducing drag and preventing fouling in ships. Attached Figure Description

[0023] Figure 1 A schematic diagram of the oleogel preparation process (a), the chemical equation of the polyurethane prepolymer (b), and the chemical equation of the polyurethane-polyurea skeleton (c).

[0024] Figure 2 It is the infrared spectrum of polyurethane-polyurea backbone, polyurethane prepolymer, and isophorone diisocyanate;

[0025] Figure 3 The Raman spectra of oleogel-3-3-3, graphite oxide powder, and multi-walled carbon nanotubes are shown.

[0026] Figure 4 Fluorescence microscopy of the distribution of hydroxyl-terminated dimethyl silicone oil labeled with fluorescein isothiocyanate in oleogel.

[0027] Figure 5 This is an optical photograph of the self-healing properties of oleogel-3-3-3;

[0028] Figure 6 These are the Tafel curves for aluminum substrate, waterborne polyurethane, and oleogel -3-3-3;

[0029] Figure 7 This is an AFM image of oleogel-3-3-3;

[0030] Figure 8 It refers to the zeta potential of waterborne polyurethane, oleogel-3-3-0, oleogel-3-3-1, and oleogel-3-3-3;

[0031] Figure 9 The photothermal conversion capability of aluminum substrate, waterborne polyurethane, oleogel-3-0-3, oleogel-3-1-3, oleogel-3-3-3, and oleogel-3-5-3 under xenon lamp simulation of 1 solar intensity;

[0032] Figure 10 These are the stress-strain curves of oleogel-0-3-3, oleogel-1-3-3, oleogel-2-3-3, oleogel-3-3-3, oleogel-4-3-3, and oleogel-5-3-3.

[0033] Figure 11 The following are examples of materials used: aluminum substrate, waterborne polyurethane, oleogel-3-3-0, oleogel-3-3-1, and oleogel-3-3-3: (a) confocal fluorescence micrographs showing resistance to protein adhesion; (b) colony count on coated plates after vigorous shaking, showing resistance to Staphylococcus aureus, Escherichia coli, and Shewanella putrefactive bacteria adhesion; (c) antibacterial rate against Staphylococcus aureus; (d) antibacterial rate against Escherichia coli; and (e) antibacterial rate against Shewanella putrefactive bacteria.

[0034] Figure 12 These are optical photographs of aluminum substrates, waterborne polyurethane, oleogel-3-3-0, oleogel-3-3-1, and oleogel-3-3-3 against flat algae or small crescent-shaped rhomboid algae, taken at 1d and 7d. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings and specific examples.

[0036] A schematic diagram of the preparation mechanism of the oleogel with lubricating and antifouling functions described in this invention is shown below. Figure 1As shown in Figure a, polytetrahydrofuran, isophorone diisocyanate, and the catalyst dibutyltin dilaurate are added to a three-necked flask equipped with a nitrogen inlet, a paddle stirrer, and a reflux condenser. The paddle stirrer is turned on at 300 rpm, the nitrogen valve is opened, and the mixture is heated to 75-85°C in an oil bath and stirred for 3.5-5 hours to generate a polyurethane prepolymer. The reactions involved are as follows. Figure 1 As shown in Figure b, 4,4'-dithiodiphenylamine and acetone are added, and the mixture is stirred at 75-85°C for 1.5-2.5 h to generate a polyurethane-polyurea skeleton. The reactions involved are as follows. Figure 1 As shown in Figure c, dimethyl silicone oil, silane coupling agent, graphite oxide powder, multi-walled carbon nanotube hybrids, nanocellulose crystals, and sodium laurate in different proportions were added to a beaker. The silane coupling agent facilitated better and more uniform mixing in the dimethyl silicone oil. The mixture was ultrasonically sonicated to obtain a mixed oil solution. This mixed oil solution was then added to a three-necked flask and stirred at 75–85°C for 1.5–2.5 h. Acetone was added during stirring to dilute the viscosity. After stirring for 1 h, an oleogel, xyz, was obtained. Here, x represents the mass percentage of nanocellulose crystals in the oleogel, y represents the mass percentage of graphite oxide powder and multi-walled carbon nanotube hybrids in the oleogel, and z represents the mass percentage of sodium laurate in the oleogel.

[0037] The molar ratio of isophorone diisocyanate to polytetrahydrofuran is 2.2:0.8~1.2, the content of the catalyst dibutyltin dilaurate in the polyurethane-polyurea skeleton is 0.01wt%~0.5wt%, the molar ratio of isophorone diisocyanate to 4,4'-dithiodiphenylamine is 2.2:1~1.4, the content of nanocellulose crystals in the olegel is 1wt%~5wt%, the content of graphite oxide powder and multi-walled carbon nanotubes in the olegel is 1wt%~5wt%, and the content of sodium laurylate in the olegel is 0wt%~3wt%.

[0038] like Figure 2 As shown, isophorone diisocyanate at 2269 cm⁻¹ -1 The characteristic peak of -N=C=O is located at 1594 cm⁻¹. After reacting with polytetrahydrofuran, the characteristic peak of -N=C=O in the polyurethane prepolymer weakens, and the peak at 1594 cm⁻¹ decreases. -1 and 1491 cm -1 The appearance of new characteristic peaks at the locations is attributed to the stretching vibrations of -C=O and secondary amines, respectively, indicating that some of the -N=C=O in isophorone diisocyanate reacts with the -OH in polytetrahydrofuran to form urethane bonds. The complete disappearance of the characteristic peak of -N=C=O in the polyurethane-polyurea skeleton is because 4,4'-dithiodiphenylamine acts as a chain extender, and its -NH2 reacts with the remaining -N=C=O in isophorone diisocyanate to form urea bonds, proving the successful formation of the polyurethane-polyurea skeleton.

[0039] Example 1:

[0040] 1) Add 2.445 g of isophorone diisocyanate, 5 g of polytetrahydrofuran (Mv=1000) and 0.015 wt% dibutyltin dilaurate to a three-necked flask and heat at 80 °C for 4 h under nitrogen atmosphere to generate polyurethane prepolymer.

[0041] 2) 1.49 g of 4,4'-dithiodiphenylamine was added to the polyurethane prepolymer as a chain extender. The reaction was carried out at 80°C for 2 h under nitrogen atmosphere to generate a polyurethane-polyurea skeleton. 25 ml of acetone was added to reduce the viscosity.

[0042] 3) Dimethyl silicone oil, 0.3wt% silane coupling agent, 3wt% nanocellulose crystals, 3wt% graphite oxide powder and multi-walled carbon nanotubes, and 0wt% sodium laurylate were ultrasonicated for 30 min to obtain a mixed oil solution, which was added to a polyurethane-polyurea skeleton. 25 ml of acetone was added to reduce the viscosity, and the mixture was heated at 80℃ for 1 h to generate an oil gel.

[0043] The prepared oleogel was applied to the substrate surface and cured for 7 days to form an oleogel coating.

[0044] The prepared oleogel-3-3-0 has a zeta potential of -29.04613 mV at pH 8, exhibiting excellent anti-algae properties, an anti-protein rate of 57.12%, and antibacterial rates of 96.72%, 88.18%, and 97.43% against Staphylococcus aureus, Escherichia coli, and Shewanella putrefactive bacteria, respectively.

[0045] Example 2:

[0046] 1) Add 2.445 g of isophorone diisocyanate, 5 g of polytetrahydrofuran (Mv=1000) and 0.015 wt% dibutyltin dilaurate to a three-necked flask and heat at 80 °C for 4 h under nitrogen atmosphere to generate polyurethane prepolymer.

[0047] 2) 1.49 g of 4,4'-dithiodiphenylamine was added to the polyurethane prepolymer as a chain extender. The reaction was carried out at 80°C for 2 h under nitrogen atmosphere to generate a polyurethane-polyurea skeleton. 25 ml of acetone was added to reduce the viscosity.

[0048] 3) Dimethyl silicone oil, 0.3wt% silane coupling agent, 3wt% nanocellulose crystals, 3wt% graphite oxide powder and multi-walled carbon nanotubes, and 1wt% sodium laurylate were ultrasonicated for 30 min to obtain a mixed oil solution, which was then added to a polyurethane-polyurea skeleton. 25 ml of acetone was added to reduce the viscosity, and the mixture was heated at 80℃ for 1 h to generate an oil gel.

[0049] The prepared oleogel was applied to the substrate surface and cured for 7 days to form an oleogel coating.

[0050] The prepared oleogel-3-3-1 has a zeta potential of -31.51718 mV at pH 8, exhibiting excellent anti-algae properties, an anti-protein rate of 70.06%, and antibacterial rates of 99.10%, 94.34%, and 98.97% against Staphylococcus aureus, Escherichia coli, and Shewanella putrefactive bacteria, respectively.

[0051] Example 3:

[0052] 1) Add 2.445 g of isophorone diisocyanate, 5 g of polytetrahydrofuran (Mv=1000) and 0.015 wt% dibutyltin dilaurate to a three-necked flask and heat at 80 °C for 4 h under nitrogen atmosphere to generate polyurethane prepolymer.

[0053] 2) 1.49 g of 4,4'-dithiodiphenylamine was added to the polyurethane prepolymer as a chain extender. The reaction was carried out at 80°C for 2 h under nitrogen atmosphere to generate a polyurethane-polyurea skeleton. 25 ml of acetone was added to reduce the viscosity.

[0054] 3) Dimethyl silicone oil, 0.3wt% silane coupling agent, 3wt% nanocellulose crystals, 3wt% graphite oxide powder and multi-walled carbon nanotubes, and 3wt% sodium laurylate were ultrasonicated for 30 min to obtain a mixed oil solution, which was added to a polyurethane-polyurea skeleton. 25 ml of acetone was added to reduce the viscosity, and the mixture was heated at 80℃ for 1 h to generate an oil gel.

[0055] The prepared oleogel was applied to the substrate surface and cured for 7 days to form an oleogel coating.

[0056] The prepared oleogel-3-3-3 has a zeta potential of -42.77345 mV at pH 8, exhibiting excellent anti-algae properties, an anti-protein rate of 72.05%, and antibacterial rates of 99.30%, 89.16%, and 99.23% against Staphylococcus aureus, Escherichia coli, and Shewanella putrefactive bacteria, respectively.

[0057] like Figure 3 As shown, the Raman spectrum of oleogel-3-3-3 is at 478 cm⁻¹. -1 and 1086 cm -1 The presence of characteristic peaks for multi-walled carbon nanotubes at 1348 cm⁻¹ indicates that multi-walled carbon nanotubes were successfully introduced. -1 and 1592 cm -1 The presence of D and G peaks of graphite oxide powder at 2905 cm⁻¹ indicates that graphite oxide powder was successfully introduced. -1 The characteristic peak at that location is generated by the -CH stretching vibration of the oleogel.

[0058] like Figure 4 As shown, in the oleogel prepared by fluorescent dye conjugating dimethyl silicone oil, the fluorescence signal generated by the fluorescent dye conjugated dimethyl silicone oil was observed to be uniformly distributed, indicating that dimethyl silicone oil can be uniformly distributed in the oleogel.

[0059] like Figure 5 As shown, a five-pointed star-shaped oleogel-3-3-3 was cut into two parts and allowed to self-heal for a period of time. When the oleogel-3-3-3 was picked up with tweezers, the cut was found to be completely self-healed, with no visible cut mark. Applying outward force to both ends with two tweezers, the cut was found to have completely healed together and possessed a certain tensile strength. This is because the oleogel contains -SS bonds, and disulfide bonds can break under external stimuli and reform under appropriate conditions. This dynamic fracture and regeneration characteristic allows the material to automatically repair itself after damage. Furthermore, the -C=O and -NH bonds on the polyurethane-polyurea backbone of the oleogel, and the -OH bonds on the nanocellulose crystals and graphite oxide powder, promote the self-healing process through strong intermolecular hydrogen bonds, thus achieving the material's self-repair process.

[0060] Tafel polarization curve as follows Figure 6 As shown, the self-corrosion current of the aluminum substrate is 10. -9.4107 The self-corrosion current of waterborne polyurethane is 10. -10.2251 The self-corrosion current of oleogel-3-3-3 is 10. -11.7250 The oleogel-3-3-3 exhibits the lowest self-corrosion current and the slowest corrosion rate. The self-corrosion potential reflects the thermodynamic stability and corrosion tendency of a material in a specific environment; a higher self-corrosion potential indicates a more stable state. The self-corrosion potential of oleogel-3-3-3 is higher than that of aluminum substrates and waterborne polyurethane. This demonstrates the excellent corrosion resistance of oleogel-3-3-3.

[0061] like Figure 7 As shown, AFM shows that the average roughness of oleogel-3-3-3 is 9.05 nm. When the surface roughness is smaller than the size of the bacteria themselves, the bacteria are unlikely to adhere to the surface. The nanoscale roughness of the oleogel makes it difficult for bacteria to adhere, which can prevent the initial adhesion of bacteria and prevent biocontamination.

[0062] like Figure 8 As shown, the pH of seawater is around 8.0, at which point the potential of the waterborne polyurethane is -19.83758 mV, possibly due to Cl... -Ions adsorb onto the polyurethane surface through electrostatic interactions and hydrogen bonding, resulting in a negative zeta potential. The zeta potential of the oleogel-3-3-0 is -29.04613 mV because the addition of nano-cellulose crystals, multi-walled carbon nanotubes, and graphite oxide powder significantly enhances hydrogen bonding and increases the Cl- concentration. - The adsorption further reduces the surface potential of the oleogel. The potential of oleogel-3-3-1 is -31.51718 mV. Sodium laurate ionizes into laurate ions at pH 8, which are negatively charged, further reducing the potential. Furthermore, by increasing the proportion of sodium laurate, the potential of oleogel-3-3-3 is -42.77345 mV. Through electrostatic repulsion, it can prevent the adhesion of microorganisms, thereby improving the antibacterial properties and service life of the surface.

[0063] Example 4:

[0064] Example 4 operates on the same steps as Example 3, except that the mass ratio of nanocellulose crystals in step 3) of Example 3 is changed to 0wt%, 1wt%, 2wt%, 3wt%, 4wt%, and 5wt%.

[0065] The strains of the prepared oleogels-0-3-3, oleogel-1-3-3, oleogel-2-3-3, oleogel-3-3-3, oleogel-4-3-3, and oleogel-5-3-3 were 1950.64%, 2708.30%, 2762.37%, 3020.12%, 3002.35%, and 2477.52%, respectively, and the maximum stresses were 32.61 KPa, 48.17 KPa, 88.62 KPa, 150.39 KPa, 158.31 KPa, and 165.25 KPa, respectively, exhibiting excellent mechanical strength and high strain.

[0066] Example 5:

[0067] Example 5 operates on the same steps as Example 3, except that the mass ratio of graphite oxide powder and multi-walled carbon nanotubes in step 3) of Example 3 is changed to 0wt%, 1wt%, 3wt%, 5wt%, and 10wt%, respectively.

[0068] When the mass of graphite oxide powder and multi-walled carbon nanotubes reaches 10 wt% (3-10-3), oleogel cannot be formed due to agglomeration. The prepared oleogels-3-0-3, oleogel-3-1-3, oleogel-3-3-3, and oleogel-3-5-3 have surface temperatures of 36.8℃, 41℃, 51.2℃, and 52.4℃ respectively after 360 s of irradiation with one solar intensity, exhibiting excellent photothermal conversion ability and antibacterial effect.

[0069] like Figure 9As shown, the surface temperatures of aluminum alloy and waterborne polyurethane increased slightly due to direct xenon lamp irradiation. The surface temperatures of oleogel-3-0-3 and oleogel-3-1-3 were higher because the cross-linked structure of oleogel can store energy. The addition of dimethyl silicone oil filled the gaps in the oleogel, slowing down heat loss. Graphite oxide powder and multi-walled carbon nanotubes have excellent photothermal conversion performance. Since carbon-based materials have a wide visible light absorption range, when they are exposed to a light source, the electrons in them can absorb the energy of photons, thus putting the electrons in an excited state. Electrons in the excited state are unstable and will generate a photothermal effect during the decay back to the ground state, thus increasing the surface temperature of oleogel-3-3-3. As its content increases, the photothermal conversion efficiency becomes higher, and the surface temperature of oleogel increases. In olegel-3-3-3 and olegel-3-5-3, the surface temperatures reached 51.2℃ and 52.4℃ respectively after 360 seconds of sun irradiation. 50℃ is a sublethal temperature for bacteria such as E. coli, potentially leading to protein denaturation and reduced enzyme activity; therefore, the coating can provide antibacterial protection. The photothermal conversion efficiency of olegel-3-5-3 is not significantly improved compared to olegel-3-3-3, and the high proportion of graphite oxide powder may cause agglomeration, reducing mechanical properties. In 3-10-3, the high content of graphite oxide powder and multi-walled carbon nanotubes prevents the formation of an olegel, and the high proportion of graphite oxide powder also increases material costs.

[0070] Stress-strain curves of oleogels with different proportions of nanocellulose crystals are shown below. Figure 10As shown, all oleogels exhibit elastic deformation at low strain. The distance between molecules increases, but due to the strong intermolecular binding force, the stress increases linearly with increasing strain, eventually reaching a peak stress. When the strain exceeds the elastic limit, the material begins to undergo plastic deformation. Internal particles begin to slide relative to each other, generating significant frictional and viscoelastic forces. The maximum stress values ​​for oleogels-0-3-3, oleogels-1-3-3, oleogels-2-3-3, oleogels-3-3-3, oleogels-4-3-3, and oleogels-5-3-3 are 32.61 kPa, 48.17 kPa, 88.62 kPa, 150.39 kPa, 158.31 kPa, and 165.25 kPa, respectively. Nanocellulose crystals are a green and sustainable material with a high specific surface area and high crystallinity. Their molecular structure exhibits a highly ordered arrangement and a strong hydrogen bond network, and they also have good dispersibility. With increasing nanocellulose crystal content, the peak stress of the oleogel gradually increases. The increase is significant from oleogel-0-3-3 to oleogel-3-3-3. Further increases in content result in a smaller increase in peak stress. The nanocellulose crystals form strong intermolecular hydrogen bonds with polyurethane-polyurea fragments, acting as physical cross-linking points and enhancing the overall mechanical properties of the oleogel. After the peak stress, the tensile stress decreases slowly with increasing strain. All oleogels exhibit remarkable elongation. The strains of oleogel-0-3-3, oleogel-1-3-3, oleogel-2-3-3, oleogel-3-3-3, oleogel-4-3-3, and oleogel-5-3-3 are 1950.64%, 2708.30%, 2762.37%, 3020.12%, 3002.35%, and 2477.52%, respectively. As the content of nanocellulose crystals increases, the elongation first increases and then decreases. The high toughness of the formed hydrogen bonds and multi-walled carbon nanotubes prevents the olegel from breaking in the early stage of stretching. The olegel-3-3-3 exhibits the highest elongation performance. When the content of nanocellulose crystals increases further, agglomeration occurs in the material. The quality and density of the interfacial bonding cannot be fully matched with the polyurethane-polyurea skeleton, resulting in a decrease in bonding strength and affecting the toughness and elongation of the material.

[0071] like Figure 11As shown in Figure a, bovine serum albumin labeled with fluorescein isothiocyanate on the aluminum substrate surface is distributed in sheets, and the fluorescence intensity is highest when calculated using ImageJ. The fluorescence intensity displayed on the aluminum substrate surface is taken as 100%. The fluorescence intensity on the aqueous polyurethane surface is 68.1% of that on the aluminum substrate. This is because the aqueous polyurethane surface is relatively smooth. However, due to the affinity of proteins for hydrophobic surfaces, it also exhibits high adsorption on the aqueous polyurethane surface. The fluorescence intensity of oleogel-3-3-0 is 42.88%, significantly reducing protein adhesion compared to the aluminum substrate. This is because dimethyl silicone oil forms a dynamic flow layer on oleogel-3-3-0, making it difficult for proteins to adhere for a long time. The addition of sodium laurate reduces the hydrophobicity of the oleogel, increases the repulsion of protein molecules, and reduces protein adhesion. Oleogel-3-3-3 carries a negative charge at pH 8. At this pH, because the pH is greater than the isoelectric charge of proteins, the proteins also carry a negative charge, resulting in electrostatic repulsion with oleogel-3-3-3, and the protein adsorption is lowest. Antibacterial experiment ( Figure 11 As shown in b), Staphylococcus aureus, Escherichia coli, and Shewanella putrefactive bacteria adhered most strongly to the aluminum substrate and formed the most colonies after dilution and coating. Waterborne polyurethane also showed significant colony formation. However, oleogel-3-3-0, oleogel-3-3-1, and oleogel-3-3-3 had very few colonies. Figure 11 As shown in the figure, the antibacterial rates against Staphylococcus aureus were 96.72%, 99.10%, and 99.30%, respectively; against Escherichia coli, 88.18%, 94.34%, and 89.16%, respectively; and against Shewanella putrefactive bacteria, 97.43%, 98.97%, and 99.23%, respectively. The oleogel exhibits significant antibacterial effects against various bacteria. This is attributed to the formation of a dynamic lubricating layer on the surface by dimethyl silicone oil, making bacterial adhesion difficult. During a 6-hour period of simulated solar irradiation, the surface temperature of the oleogel can rise above 50°C, achieving a bactericidal effect. Furthermore, with increasing sodium laurate content, oleogel-3-3-3 exhibits the lowest electrostatic potential, which can repel bacterial adhesion through strong electrostatic repulsion (however, excessive sodium laurate can lead to phase separation of the coating, reducing coating adhesion and mechanical strength). Simultaneously, the nanoscale roughness of the oleogel-3-3-3 surface is unfavorable for bacterial adhesion, thus oleogel-3-3-3 displays excellent antibacterial effects.

[0072] like Figure 12As shown, *Platycodon grandiflorus* and *Nyctaginus simonii* adhered to the aluminum substrate and aqueous polyurethane surface after 1 day of cultivation. After 7 days of cultivation, the deposition of *Platycodon grandiflorus* and *Nyctaginus simonii* on the aluminum substrate and aqueous polyurethane surface increased, especially *Platycodon grandiflorus*, which formed a biofilm. However, no algal adhesion was observed on the oleogel surface. This is attributed to the dynamic lubrication layer formed by dimethyl silicone oil on the oleogel surface, which makes it difficult for algae to adhere. The low surface energy and negative charge of oleogel-3-3-3 can also inhibit algal adhesion through strong electrostatic interaction, thus exhibiting good anti-algae properties.

Claims

1. A method for preparing an oleogel with lubricating and antifouling functions, characterized in that, Specifically, the preparation steps include the following: 1) Using dibutyltin dilaurate as a catalyst, isophorone diisocyanate and polytetrahydrofuran are heated at 75~85℃ for 3.5~5h under nitrogen atmosphere to generate polyurethane prepolymer; 2) 4,4'-dithiodiphenylamine was added to the polyurethane prepolymer as a chain extender and heated at 75~85℃ for 1.5~2.5 h under nitrogen atmosphere to generate a polyurethane-polyurea skeleton. Acetone was added during the reaction to reduce the viscosity of the system. 3) Mix dimethyl silicone oil, silane coupling agent, nanocellulose crystals, graphite oxide powder, multi-walled carbon nanotubes and sodium laurylate, and disperse them evenly by ultrasonication to obtain a mixed oil solution. Add the mixed oil solution to the polyurethane-polyurea skeleton, add acetone to reduce the viscosity, and heat at 75~85℃ for 0.5~1.5 h to generate the oil gel. In step 3), the content of nanocellulose crystals in the oleogel is 1wt%~5wt%; In step 3), the total content of graphite oxide powder and multi-walled carbon nanotubes in the oleogel is 1wt%~5wt%, and the mass ratio of graphite oxide powder to multi-walled carbon nanotubes is 1:

1. In step 3), the content of sodium lauryl in the oleogel is 1wt%~3wt%.

2. The method for preparing an oil gel with lubricating and antifouling functions as described in claim 1, characterized in that, In step 1), the molar ratio of isophorone diisocyanate to polytetrahydrofuran is 2.2:0.8~1.

2.

3. The method for preparing an oleogel with lubricating and antifouling functions as described in claim 1, characterized in that, In step 2), the amount of 4,4'-dithiodiphenylamine used is: the molar ratio of isophorone diisocyanate to 4,4'-dithiodiphenylamine is 2.2:1~1.

4.

4. The method for preparing an oleogel with lubricating and antifouling functions as described in claim 1, characterized in that, In step 1), the content of dibutyltin dilaurate in the polyurethane-polyurea backbone is 0.01wt%~0.5wt%.

5. The method for preparing an oil gel with lubricating and anti-fouling functions as described in claim 1, characterized in that, In step 1), the heating temperature is 80℃ and the heating reaction time is 4 h; in step 2), the heating temperature is 80℃ and the heating reaction time is 2 h; in step 3), the heating temperature is 80℃ and the heating reaction time is 1 h.

6. An oleogel with lubricating and anti-fouling functions, characterized in that, It is prepared by the method described in any one of claims 1-5.

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