Low-surface-energy antifouling coating with degradability, and preparation method therefor and use thereof

Abstract

The present application relates to a low-surface-energy antifouling coating with degradability, and a preparation method therefor and the use thereof. The preparation method comprises: mixing bis(3-aminopropyl)-terminated polydimethylsiloxane and diglycidyl 4-cyclohexene-1,2-dicarboxylate, followed by performing curing to obtain the product. In the present application, an epoxy containing an ester segment is polymerized with a low-surface-energy siloxane having an amino group. The ring-opening reaction between the amino group and the epoxy grafts the ester group onto the side chain of the siloxane polymer, thereby further providing degradability to the antifouling coating.

Description

A low surface energy antifouling coating with biodegradable properties, its preparation method and application Technical Field

[0001] This application relates to the field of marine antifouling coating technology, and in particular to a low surface energy antifouling coating with degradable properties, its preparation method and application. Background Technology

[0002] Marine biofouling is the undesirable accumulation of marine microorganisms, plants, and animals on the surface of underwater structures submerged in seawater, causing significant damage to marine vessel facilities and marine resources. Among numerous antifouling strategies, the application of marine antifouling coatings is the simplest, most economical, and most effective method. However, traditional antifouling coatings typically contain large amounts of antifouling agents. When these agents are released into the marine environment, they kill fouling organisms and severely harm the marine ecosystem, causing secondary pollution.

[0003] Low surface energy antifouling coatings are marine antifouling coatings that do not release antifouling agents. They are typically based on organosilicon or organofluorine polymers and have the advantages of structural stability and non-hydrolysis. Polydimethylsiloxane (PDMS) coatings are widely used as environmentally friendly antifouling coatings due to their significant characteristics such as low surface energy, low Young's modulus, and cost-effectiveness.

[0004] Biodegradable antifouling coatings are a class of antifouling materials with biodegradable ester groups. Their biodegradability comes from the ester groups in the side groups, which break down when washed by water flow, forming a self-renewing surface and improving antifouling performance. Therefore, combining low surface energy antifouling with biodegradable antifouling has become an urgent problem to be solved. Summary of the Invention

[0005] This application provides a low surface energy antifouling coating with biodegradable properties, its preparation method, and its application. In this application, an epoxy containing ester segments is polymerized with a low surface energy siloxane containing amino groups, achieving dual antifouling properties. Furthermore, the introduction of epoxy groups improves the mechanical properties of the coating. While enhancing antifouling performance, this combination also avoids potential pollution of the marine environment by polymer materials.

[0006] In a first aspect, this application provides a low surface energy antifouling coating with degradable properties, characterized in that the structure of the low surface energy antifouling coating comprises an amino group of bis(3-aminopropyl)-terminated polydimethylsiloxane linked to an epoxy group of 4-cyclohexene-1,2-dicarboxylic acid diglycidyl ester.

[0007] Preferably, the connecting chemical bond includes an ester bond.

[0008] Secondly, this application provides a method for preparing a low surface energy antifouling coating with degradable properties according to the first aspect, the method comprising:

[0009] The mixture was prepared by mixing bis(3-aminopropyl)-terminated polydimethylsiloxane and 4-cyclohexene-1,2-dicarboxylic acid diglycidyl ester and then curing the mixture.

[0010] In this application, a one-pot polymerization method is used, where the epoxy groups are opened through the polymerization reaction of NH2-PDMS with 4-cyclohexene-1,2-dicarboxylic acid diglycidyl ester, and the ester groups are grafted onto the low surface energy siloxane side chains. Its degradability originates from the ester groups in the side groups, which undergo chain scission by water flow, forming a self-renewing surface and improving antifouling performance. Therefore, combining low surface energy antifouling with degradable antifouling can effectively compensate for their respective shortcomings, thereby enhancing the overall antifouling performance of the antifouling coating.

[0011] Preferably, the molar ratio of the amino group of the bis(3-aminopropyl)-terminated polydimethylsiloxane to the epoxy group of 4-cyclohexene-1,2-dicarboxylic acid diglycidyl ester is 1:(1-5), and the (1-5) can be, for example, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 or 5.

[0012] In this application, within the above molar ratio range, 4-cyclohexene-1,2-dicarboxylic acid diglycidyl ester is fully connected with bis-3-aminopropyl-terminated polydimethylsiloxane, significantly improving the overall antifouling performance of the antifouling coating.

[0013] Preferably, the molecular weight of the bis(3-aminopropyl)-terminated polydimethylsiloxane is 2500-3000, for example, it can be 2000, 2050, 2100, 2150, 2200, 2250, 2300, 2350, 2400, 2450 or 2500.

[0014] Preferably, the preparation method further includes adding a solvent to the mixed raw materials and stirring, and then condensing and refluxing in an oil bath.

[0015] Preferably, the solvent includes any one or a combination of at least two of tetrahydrofuran, ethyl acetate, or acetone.

[0016] Preferably, the stirring time is 20-40 minutes, and the stirring speed is 100-500 rpm. The 20-40 minutes can be, for example, 20 minutes, 22 minutes, 24 minutes, 26 minutes, 28 minutes, 30 minutes, 32 minutes, 34 minutes, 36 minutes, 38 minutes, or 40 minutes. The 100-500 rpm can be, for example, 100 rpm, 150 rpm, 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm, 450 rpm, or 500 rpm.

[0017] Preferably, the temperature of the oil bath is 75-85℃, for example, it can be 75℃, 76℃, 77℃, 78℃, 79℃, 80℃, 81℃, 82℃, 83℃, 84℃ or 85℃, etc.

[0018] Preferably, the condensation reflux time is 20-24 hours, for example, it can be 20 hours, 21 hours, 22 hours, 23 hours or 24 hours.

[0019] Preferably, the curing time is 3-7 days, for example, 3 days, 4 days, 5 days, 6 days or 7 days.

[0020] Preferably, the curing temperature is 20-30℃, for example, it can be 20℃, 21℃, 22℃, 23℃, 24℃, 25℃, 26℃, 27℃, 28℃, 29℃ or 30℃, etc.

[0021] Preferably, the preparation method further includes immersing the cured coating in silicone oil.

[0022] In this application, the cured coating is immersed in silicone oil to form an ultra-slippery antifouling surface, thereby obtaining a smooth and relatively new coating surface that will not cause high molecular pollution to the ocean, and ultimately achieves excellent marine antifouling effect.

[0023] Preferably, the silicone oil includes any one or a combination of at least two of methyl silicone oil, ethyl silicone oil, phenyl silicone oil, or fluorinated silicone oil.

[0024] Preferably, the viscosity of the silicone oil is 5-100 mPa·s, for example, it can be 5 mPa·s, 10 mPa·s, 20 mPa·s, 40 mPa·s, 60 mPa·s, 80 mPa·s or 100 mPa·s, etc.

[0025] Preferably, the soaking time is 3-7 days, for example, 3 days, 4 days, 5 days, 6 days or 7 days.

[0026] In this application, an immersion experiment was conducted to investigate the degradability of the coating. The steps of the immersion experiment included immersing the coating in artificial seawater, drying off the residual moisture on its surface, reweighing the mass, and judging the degradation performance of the coating.

[0027] Preferably, the coating is immersed in artificial seawater for 30-120 days, for example, 30 days, 40 days, 60 days, 80 days, 100 days or 120 days.

[0028] Preferably, the mass ratio of the coating to the artificial seawater is 1:(100-200). The (100-200) can be, for example, 100, 120, 140, 160, 180, or 200.

[0029] Preferably, the temperature at which the moisture on the surface of the drying coating is dried is 55-65°C. The 55-65°C can be, for example, 55°C, 56°C, 57°C, 58°C, 59°C, 60°C, 61°C, 62°C, 63°C, 64°C, or 65°C.

[0030] Thirdly, this application provides an application of the low surface energy antifouling coating with degradable properties described in the first aspect in the treatment of marine biofouling.

[0031] Compared with the prior art, this application has at least the following beneficial effects:

[0032] (1) This application polymerizes epoxy containing ester segments with low surface energy siloxane with amino groups, and uses the ring-opening reaction of amino and epoxy to graft ester groups onto the side chain of siloxane polymer, thereby achieving the synergy of degradability and low surface energy, and further providing degradability for antifouling coatings.

[0033] (2) This application has excellent smoothness, environmental friendliness and biodegradability, and the super-smooth surface itself has antifouling properties. The preparation process is simple, retains the excellent smoothness of the super-smooth surface, and its low surface energy significantly reduces the adhesion of marine organisms to the surface.

[0034] (3) The coating studied can also form a super-slippery antifouling surface by injecting silicone oil, thereby obtaining a smooth and relatively new coating surface that will not cause high molecular pollution to the ocean, ultimately achieving excellent marine antifouling effect. The addition of epoxy groups improves the mechanical properties of the coating, achieving a synergistic effect of multiple antifouling effects. Attached Figure Description

[0035] Figure 1 is a schematic diagram of the molecular formula of a low surface energy antifouling coating substrate with biodegradable properties.

[0036] Figure 2 is a scanning electron microscope schematic diagram of the low surface energy antifouling coating substrate with degradable properties, wherein Figure A is the coating surface of Example 4, Figure B is the coating cross-section of Example 4, Figure C is the coating surface of Example 1, and Figure D is the coating cross-section of Example 1.

[0037] Figure 3 is a schematic diagram of the infrared spectrum of the flocculent material obtained after soaking in artificial seawater in Example 1.

[0038] Figure 4 is a schematic diagram of the antibacterial effect of the low surface energy antifouling coating with degradable properties, where Figure A is the result of the blank sample, Figure B is the result of Example 1, Figure C is the result of Example 2, Figure D is the result of Example 3, Figure E is the result of Example 4, Figure F is the result of Example 5, Figure G is the result of Example 6, Figure H is the result of Comparative Example 1, Figure I is the result of Comparative Example 2, and Figure J is the result of Comparative Example 3. Detailed Implementation

[0039] The technical solution of this application will be further described below with reference to the accompanying drawings and specific embodiments. However, the examples below are merely simplified examples of this application and do not represent or limit the scope of protection of this application. The scope of protection of this application shall be determined by the claims.

[0040] Example 1

[0041] This embodiment prepares a low surface energy antifouling coating with biodegradable properties.

[0042] 2.5g of bis(3-aminopropyl)-terminated polydimethylsiloxane (molecular weight 2500) and 0.15g of 4-cyclohexene-1,2-dicarboxylic acid diglycidyl ester were mixed at a functional group molar ratio of 1:1. 10g of tetrahydrofuran solvent was added, and the mixture was stirred for 30 minutes until the oily liquid was completely dissolved at a speed of 300 rpm. The mixture was then transferred to a flask and stirred and refluxed in an oil bath at 80°C for 20 hours. After the reaction was completed, the viscous liquid was transferred to a rigid polytetrafluoroethylene mold (mold size 15*15*2mm) and dried and cured at 25°C for 3 days.

[0043] The cured coating was immersed in 10g of dimethyl silicone oil with a viscosity of 100mPa·s for 3 days to swell. After 3 days, the coating was removed and any residual silicone oil adhering to the surface was cleaned off.

[0044] Example 2

[0045] This embodiment prepares a low surface energy antifouling coating with biodegradable properties.

[0046] 2.5g of bis(3-aminopropyl)-terminated polydimethylsiloxane (molecular weight 2500) and 0.45g of 4-cyclohexene-1,2-dicarboxylic acid diglycidyl ester were mixed at a functional group molar ratio of 1:3. 10g of tetrahydrofuran solvent was added, and the mixture was stirred for 30 minutes until the oily liquid was completely dissolved at 300 rpm. The mixture was then transferred to a flask and stirred and refluxed in an oil bath at 80°C for 20 hours. After the reaction was completed, the viscous liquid was transferred to a rigid polytetrafluoroethylene mold (mold size 15*15*2mm) and dried and cured at 25°C for 3 days.

[0047] The cured coating was immersed in 10g of dimethyl silicone oil with a viscosity of 100mPa·s for 3 days to swell. After 3 days, the coating was removed and any residual silicone oil adhering to the surface was cleaned off.

[0048] Example 3

[0049] This embodiment prepares a low surface energy antifouling coating with biodegradable properties.

[0050] 2.5g of bis(3-aminopropyl)-terminated polydimethylsiloxane (molecular weight 2500) and 0.75g of 4-cyclohexene-1,2-dicarboxylic acid diglycidyl ester were mixed at a functional group molar ratio of 1:5. 10g of tetrahydrofuran solvent was added, and the mixture was stirred for 20 minutes until the oily liquid was completely dissolved at a speed of 500 rpm. The mixture was then transferred to a flask and stirred and refluxed in an oil bath at 75°C for 24 hours. After the reaction was completed, the viscous liquid was transferred to a rigid polytetrafluoroethylene mold (mold size 15*15*2mm) and dried and cured at 30°C for 5 days.

[0051] The cured coating was immersed in 10g of dimethyl silicone oil with a viscosity of 50mPa·s for 7 days to swell. After 7 days, the coating was removed and any residual silicone oil adhering to the surface was cleaned.

[0052] Example 4

[0053] This embodiment prepares a low surface energy antifouling coating with degradable properties. The only difference between this embodiment and Example 1 is that the prepared coating is not immersed in silicone oil. Otherwise, it is the same as Example 1.

[0054] Example 5

[0055] This embodiment prepares a low surface energy antifouling coating with biodegradable properties. The only difference between this embodiment and Example 1 is that the mass of bis(3-aminopropyl)-terminated polydimethylsiloxane (molecular weight 2500) is 2.5 g, and the mass of 4-cyclohexene-1,2-dicarboxylic acid diglycidyl ester is 0.1 g, that is, the molar ratio of the functional groups of bis(3-aminopropyl)-terminated polydimethylsiloxane and 4-cyclohexene-1,2-dicarboxylic acid diglycidyl ester is 1:0.6. All other aspects are the same as in Example 1.

[0056] Example 6

[0057] This embodiment prepares a low surface energy antifouling coating with degradable properties. The only difference between this embodiment and Example 1 is that the mass of bis(3-aminopropyl)-terminated polydimethylsiloxane (molecular weight 2500) is 2.5g and the mass of 4-cyclohexene-1,2-dicarboxylic acid diglycidyl ester is 1.4g, that is, the molar ratio of the functional groups of bis(3-aminopropyl)-terminated polydimethylsiloxane and 4-cyclohexene-1,2-dicarboxylic acid diglycidyl ester is 1:7. All other aspects are the same as in Example 1.

[0058] Comparative Example 1

[0059] This comparative example prepares a low surface energy antifouling coating with degradable properties. The only difference between this example and Example 1 is that epoxy resin E44 is used instead of 4-cyclohexene-1,2-dicarboxylic acid diglycidyl ester. All other aspects are the same as in Example 1.

[0060] Comparative Example 2

[0061] This comparative example prepares a low surface energy antifouling coating with degradable properties. The only difference between this example and Example 1 is that 4-cyclohexene-1,2-dicarboxylic acid diglycidyl ester is not added. Instead, 4-cyclohexene-1,2-dicarboxylic acid diglycidyl ester is distributed into bis-3-aminopropyl-terminated polydimethylsiloxane according to the proportions in Example 1, and 2% diisophorone peroxide is added. The coating is cured at 150°C for 1 hour. All other aspects are the same as in Example 1.

[0062] Comparative Example 3

[0063] This comparative example prepares a low surface energy antifouling coating with biodegradable properties. The only difference between this example and Example 1 is that bis-3-aminopropyl-terminated polydimethylsiloxane is not added. Instead, bis-3-aminopropyl-terminated polydimethylsiloxane is distributed into 4-cyclohexene-1,2-dicarboxylic acid diglycidyl ester according to the proportions in Example 1, and 70% of the total mass of polyamide curing agent is added. The mixture is cured at 120°C for 1 hour. All other aspects are the same as in Example 1.

[0064] Test Example 1

[0065] This test case involves a biodegradability test.

[0066] The low surface energy antifouling coatings with degradable properties prepared in the above examples and comparative examples were respectively immersed in 30 mL of artificial seawater, stirred in a magnetic stirrer for 90 days, dried to remove residual moisture on the surface, and weighed again to determine the degradation performance of the coatings.

[0067] Table 1

[0068] The results in Table 1 above show that:

[0069] The biodegradability of the coatings was analyzed by immersing the coatings prepared in the examples and comparative examples in artificial seawater and recording the changes in mass. The degradation rate of each coating was calculated, revealing that the pure PDMS coating and the pure epoxy coating had no degradation ability due to the absence of degradable groups. Comparing Example 1 and Comparative Example 1, epoxy E44 did not contain degradable groups and therefore also lacked biodegradability. Comparing Example 1 and Example 4, the coating in Example 4, which was not immersed in silicone oil, exhibited biodegradability, but the degradation rate was slightly lower than that of Example 1, which contained oil. This is presumably because the silicone oil on the surface of the coating in Example 1 formed "silicone oil ridges," encapsulating a portion of the artificial seawater, resulting in a slightly higher degradation rate. Comparing Examples 1-6, the difference between these coatings lay in the varying proportions of the two raw materials. In Examples 1-3, the proportion of the two raw materials was not significantly different, resulting in a larger proportion of reaction products and a certain degradation rate. In the other coatings, the proportions of the raw materials differed too much, and only a small portion of the products exhibited biodegradability, thus failing to demonstrate biodegradability during the thirty-day immersion in artificial seawater.

[0070] The coatings obtained in Examples 1 and 4 were observed using a scanning electron microscope. Figure 2 shows the results, where A in Figure 2 represents the surface of the coating in Example 4, B represents the cross-section of the coating in Example 4, C represents the surface of the coating in Example 1, and D represents the cross-section of the coating in Example 1. As can be seen from the figures, the coating surface after immersion is very smooth, with almost no visible pores. The cross-section is also smooth. In contrast, the unoiled cross-section shows that almost all pores are filled with oil, proving that the amount of silicone oil injected is sufficient, making the originally rough surface smooth.

[0071] Test Example 2

[0072] This embodiment describes the infrared spectral characterization of the flocculent material obtained after soaking in artificial seawater.

[0073] After immersion in artificial seawater, the coating in Test Example 1 formed flocculent material. Infrared spectroscopy was performed on the flocculent material detached from the coating prepared in Example 1. The flocculent material generated by the self-degradation behavior of the coating prepared in Example 1 was filtered, dried, ground, and pressed into tablets, and its infrared spectrum was measured. Specific detection results are shown in Figure 3, where 1739 cm⁻¹... -1 The peak corresponds to C=O; 1266cm -1 The peak at 2300 cm⁻¹ corresponds to the stretching vibration of CO; -1 The peak at 1468 cm⁻¹ is attributed to the stretching vibration of C=C; -1 The peak at 2925 cm⁻¹ is due to the bending vibration of -CH₃, while the peak at 2925 cm⁻¹ is due to the bending vibration of -CH₃. -1 The peak at that location originates from the strong stretching absorption of the OH group in the carboxylic acid dimer. This proves that the product of the coating's self-degradation should be 4-cyclohexene-1,2-dicarboxylic acid.

[0074] Example 3

[0075] This embodiment demonstrates the antibacterial effect of the low surface energy antifouling coatings prepared in the above embodiments and comparative examples.

[0076] To investigate the antibacterial effects of the coatings prepared in the above examples and comparative examples, *Pseudomonas aeruginosa* was used as the test subject. First, 100 μL of *Pseudomonas aeruginosa* inoculum was placed in 10 mL of Luria-Bertani (LB) broth and incubated at a constant temperature (37°C, 180 rpm) for 6 h. Then, the bacterial suspension was centrifuged, washed with 0.9% NaCl, and resuspended. The optical density (OD) value was measured using a UV spectrophotometer (10⁻¹⁰). 8 CFU mL –1 Finally, take 10 μL of bacterial culture and dilute it to 10 mL with 0.9% NaCl solution (10). 5 CFU mL –1 ).

[0077] The prepared coatings were then placed into the bacterial suspensions described above. After incubation in a shaking incubator for 24 hours, 100 μL of the prepared bacterial suspension was taken and spread onto a solid culture medium. After incubation at 37°C for 24 hours, the number of surviving colonies was determined using the plate count method.

[0078] Table 2

[0079] The results above show that:

[0080] Figures A and J in Figure 4 show plate colony images after incubation of blank bacterial solution and the examples and comparative examples, respectively. The comparison shows that the pure epoxy coating has almost no antibacterial effect, while the other coatings have some antibacterial effect. Among them, Figure B shows the fewest colonies, indicating that Example 1 has the fewest colonies. Figure I shows the number of colonies after incubation of the coating in Comparative Example 2, which is 305. Due to the low surface energy of bis(3-aminopropyl)-terminated polydimethylsiloxane, bacteria adhere to the coating less than with the pure epoxy coating. Comparing Examples 1-5, it can be seen that when the epoxy group ratio is high, the coating surface cannot prevent bacterial adhesion because the epoxy group does not have antibacterial properties, resulting in a higher colony count. The results of Examples 1 and 2 (i.e., Figures B and C) show that the ester groups of the biodegradable coatings in Examples 1 and 2 can effectively wash away the coating surface under water flow, inhibiting bacterial adhesion. As shown in the figures, the biodegradable low surface energy coating in Example 1 exhibits excellent antibacterial adhesion effect.

[0081] In summary, in this application, the polymerization reaction of NH2-PDMS with 4-cyclohexene-1,2-dicarboxylic acid diglycidyl ester causes the epoxy group to open, grafting the ester group onto the low surface energy siloxane side chain. Its degradability comes from the ester group in the side group, which is washed away by water flow and breaks the chain, forming a self-renewing surface and improving the antifouling performance.

[0082] The applicant declares that the above description is only a specific implementation of this application, but the protection scope of this application is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application fall within the protection and disclosure scope of this application.

Claims

1. A low surface energy antifouling coating with biodegradable properties, the structure comprising an amino group of bis(3-aminopropyl)-terminated polydimethylsiloxane linked to an epoxy group of 4-cyclohexene-1,2-dicarboxylic acid diglycidyl ester.

2. The low surface energy antifouling coating with biodegradable properties according to claim 1, wherein, The bonds that connect the molecules include ester bonds.

3. A method for preparing a low surface energy antifouling coating with degradable properties according to claim 1 or 2, comprising: The mixture was prepared by mixing bis(3-aminopropyl)-terminated polydimethylsiloxane and 4-cyclohexene-1,2-dicarboxylic acid diglycidyl ester and then curing the mixture.

4. The method for preparing the low surface energy antifouling coating with degradable properties according to claim 3, wherein, The molar ratio of the amino group of the bis(3-aminopropyl)-terminated polydimethylsiloxane to the epoxy group of 4-cyclohexene-1,2-dicarboxylic acid diglycidyl ester is 1:(1-5). Preferably, the molecular weight of the bis(3-aminopropyl)-terminated polydimethylsiloxane is 2500-3000.

5. The method for preparing a low surface energy antifouling coating with degradable properties according to claim 3 or 4, wherein, The preparation method further includes adding solvent to the mixed raw materials and stirring, and then condensing and refluxing in an oil bath; Preferably, the solvent includes any one or a combination of at least two of tetrahydrofuran, ethyl acetate, or acetone.

6. The method for preparing a low surface energy antifouling coating with degradable properties according to claim 5, wherein, The stirring time is 20-40 minutes, and the stirring speed is 100-500 rpm.

7. The method for preparing a low surface energy antifouling coating with degradable properties according to claim 5 or 6, wherein, The temperature of the oil bath is 75-85℃; Preferably, the condensation reflux time is 20-24 hours.

8. The method for preparing a low surface energy antifouling coating with degradable properties according to any one of claims 3-7, wherein, The curing time is 3-7 days; Preferably, the curing temperature is 20-30℃.

9. The method for preparing a low surface energy antifouling coating with degradable properties according to any one of claims 3-7, wherein, The preparation method also includes immersing the cured coating in silicone oil.

10. The method for preparing a low surface energy antifouling coating with degradable properties according to claim 9, wherein, The silicone oil includes any one or a combination of at least two of methyl silicone oil, ethyl silicone oil, phenyl silicone oil, or fluorinated silicone oil. Preferably, the viscosity of the silicone oil is 5-100 mPa·s; Preferably, the soaking time is 3-7 days.

11. The application of a low surface energy antifouling coating with biodegradable properties as described in claim 1 or 2 in the treatment of marine biofouling.

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