Copolymer coating based on coumarin modification and preparation method and application thereof

Abstract

The copolymer comprises an isocyanate-terminated polyether polyol polymer, alpha, omega-aminopropyl-terminated polydimethylsiloxane (APT-PDMS), isophorone diisocyanate (IPDI) and a coumarin compound, the isocyanate-terminated polyether polyol polymer, the alpha, omega-aminopropyl-terminated polydimethylsiloxane (APT-PDMS), the isophorone diisocyanate (IPDI) and the coumarin compound are sequentially connected in a one-to-one manner, and the coumarin compound is a mixture of polydimethylsiloxane (APT-PDMS), polydimethylsiloxane (APT-PDMS), isophorone diisocyanate (IPDI) and coumarin. The molar ratio of the alpha, omega-aminopropyl terminated polydimethylsiloxane APT-PDMS to the isophorone diisocyanate IPDI to the coumarin compound is 1 to (1 to 2) to (0.2 to 1) to (0.1 to 0.2). When the polymer is used as an anti-fouling coating, the polymer has better mechanical properties and better fouling removal effect, can be stably attached to a substrate, is not easy to fall off, has better adhesiveness, is not easy to hydrolyze by water in seawater or air during use, has better water resistance, ensures the long-term stability of the coating, prolongs the service life of the coating, and is suitable for popularization and application. As an environment-friendly marine antifouling paint, the marine antifouling paint has a good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of marine antifouling technology, specifically relating to a coumarin-modified copolymer coating, its preparation method, and its application. Background Technology

[0002] Marine biofouling refers to the adverse accumulation of microorganisms, algae, and animals on the surface of structures submerged in seawater. This not only increases the drag of ships, accelerates metal corrosion, and increases operating costs, but also causes an increase in greenhouse gas emissions. Marine biofouling has become a key issue restricting the development of the marine industry.

[0003] Marine biofouling is a long-standing problem in marine engineering. Antifouling coatings are currently a common and effective method to alleviate this problem. However, most coatings on the market use self-polishing types with organotin as antifouling agents or contain toxic fillers, which have caused significant negative impacts on the marine ecosystem and have been banned. The release and accumulation of these toxic substances in seawater not only disrupts the balance of the marine ecosystem but may also be transmitted to humans through the food chain, posing a potential threat to human health. Therefore, developing environmentally friendly antifouling coatings that can effectively prevent biofouling while being harmless to the environment has become an urgent task facing both academia and industry.

[0004] With advancements in technology and increased environmental awareness, more and more research teams and companies are focusing on and investing in the development of environmentally friendly antifouling coatings. They are dedicated to developing new non-toxic, low-toxic, or biodegradable antifouling agents, and improving the antifouling performance and durability of coatings while reducing negative environmental impacts by optimizing coating formulations and application processes. Among these, silicone resins, with their strong (Si-O) bond energy and flexible bond angles in their siloxane backbone, exhibit particularly stable Si-O-Si main chains and excellent weather resistance. In particular, the relatively weak intermolecular forces of their methyl groups enhance the water resistance of silicone coatings and reduce surface free energy. Polyurea, a polymer structure formed through the addition polymerization of isocyanates and amino compounds, possesses unique advantages due to its strong intermolecular hydrogen bonds, exhibiting excellent mechanical properties, toughness, and strain response, and has been widely used in various fields. Its rapid curing characteristics and significant cost-effectiveness make it an ideal choice for the preparation of hydrophobic protective coatings. Currently, some related products have been launched on the market, but they still have problems such as poor antifouling effect, low mechanical strength, and easy wear, making it difficult to meet the antifouling needs of long-term static or low-speed marine facilities.

[0005] 7-Amino-4-methylcoumarin (AMC), a natural substance, has attracted much attention due to its unique antibacterial properties and UV fluorescence response. Existing literature reports that grafting 7-amino-4-methylcoumarin as a functional antifouling group into polymer chains can impart self-release properties to the coating, achieving long-lasting antifouling effects and further enhancing antifouling performance. Although antifouling coatings grafted with 7-amino-4-methylcoumarin exhibit some synergistic optimization in mechanical properties, surface properties, and bioactivity, their overall performance has not yet reached an ideal state. Certain indicators, such as adhesion (strength of adhesion to the substrate) and water resistance, have not been simultaneously improved, leading to certain limitations in practical applications. Summary of the Invention

[0006] Therefore, the purpose of this invention is to provide a coumarin-modified copolymer coating, its preparation method, and its application, in order to solve the technical problem that the comprehensive performance of current composite antifouling coating materials, such as mechanical properties, antifouling properties, adhesion properties, and water resistance properties, still needs to be improved.

[0007] The above-mentioned objective of this invention is achieved through the following technical solution: A first aspect of the present invention is to provide a coumarin-modified copolymer comprising an isocyanate-terminated polyether polyol polymer, α,ω-aminopropyl-terminated polydimethylsiloxane APT-PDMS, isophorone diisocyanate IPDI, and a coumarin compound, wherein the molar ratio of the isocyanate-terminated polyether polyol polymer, α,ω-aminopropyl-terminated polydimethylsiloxane APT-PDMS, isophorone diisocyanate IPDI, and the coumarin compound is 1:(1-2):(0.5-1):(0.1-0.2).

[0008] In one alternative embodiment, the coumarin compound is 7-amino-4-methylcoumarin (AMC).

[0009] In one optional embodiment, the isocyanate-terminated polyether polyol polymer is polypropylene glycol, specifically the toluene-2,4-diisocyanate-terminated polymer PPGTD.

[0010] A second aspect of the present invention is to provide a method for preparing the coumarin-modified copolymer, comprising the following steps: (1) Dissolve the isocyanate-terminated polyether polyol polymer in tetrahydrofuran (THF) to obtain a first solution, dissolve the α,ω-aminopropyl-terminated polydimethylsiloxane (APT-PDMS) in tetrahydrofuran (THF) to obtain a second solution, add the second solution to the first solution dropwise at a rate of 1 drop / 3-4 s under nitrogen protection, and after the addition is complete, keep the temperature constant and react. After the reaction is complete, obtain the first mixture. (2) Dissolve isophorone diisocyanate (IPDI) in tetrahydrofuran (THF) to obtain a third solution. Add the third solution dropwise to the first mixture at a rate of 1 drop / 3-4 s under nitrogen protection. After the addition is completed, carry out a constant temperature reaction under nitrogen protection and magnetic stirring. After the reaction is completed, obtain a second mixture. (3) Dissolve coumarin compounds in tetrahydrofuran (THF), then add dibutyltin dilaurate (DBTDL) to obtain a fourth solution. Add the fourth solution to the second mixture at a rate of 1 drop / 3-4 s under nitrogen protection. After the addition is completed, react at a constant temperature. After the reaction is completed, obtain a third mixture. (4) After removing the excess tetrahydrofuran (THF) solvent from the third mixture, vacuum drying was performed to obtain a coumarin-modified polyurea organosilicon copolymer.

[0011] In one optional embodiment, in step (1), the uniform dripping time is 25 to 30 minutes; the isothermal reaction temperature is 40 to 45°C, and the time is 4 to 7 hours.

[0012] In one alternative embodiment, in step (2), the uniform dripping time is 40-45 min, the constant temperature reaction temperature is 50-55℃, and the time is 4-7 h.

[0013] In one alternative embodiment, in step (3), the uniform dripping time is 30-35 min, the constant temperature reaction temperature is 55-60℃, and the time is 6-10 h.

[0014] In one alternative embodiment, in step (4), the vacuum drying temperature is 60-65°C and the time is 44-48h.

[0015] A third aspect of the invention is to provide the application of the coumarin-modified copolymer in marine antifouling coatings.

[0016] Compared with the prior art, the technical solution of the present invention has the following advantages: This invention uses polypropylene glycol-tolyl-2,4-diisocyanate-terminated polymer PPGTD as the hard segment, α,ω-aminopropyl-terminated polydimethylsiloxane APT-PDMS as the soft segment, and isophorone diisocyanate IPDI as the crosslinking agent to gradually polymerize and form a prepolymer. Then, 7-amino-4-methylcoumarin (AMC) is introduced as a functional monomer to achieve coumarin functional group grafting. The resulting copolymer, when used as an antifouling coating, exhibits good mechanical properties, excellent fouling removal effect, and stable adhesion to the substrate, showing good adhesion. Furthermore, it is not easily hydrolyzed by seawater or moisture in the air, demonstrating good water resistance, thus ensuring the long-term stability of the coating and extending its service life. This comprehensively improves the overall performance of the coating and makes it a promising environmentally friendly marine antifouling coating. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the synthetic route of the polymer PPGTD-PDMS-IPDI-x-AMC in an embodiment of the present invention; Figure 2 The above is the 1H NMR spectrum of the polymer PPGTD-PDMS-IPDI-x-AMC in an embodiment of the present invention. Figure 3 The test results of the diatom removal rate of the polymer PPGTD-PDMS-IPDI-x-AMC in the embodiments of the present invention are shown. Figure 4 The test results of the polymer PPGTD-PDMS-IPDI-x-AMC on the removal strength of simulated barnacles in the embodiments of the present invention are shown. Figure 5 The results of water absorption rate test for polymer PPGTD-PDMS-IPDI-x-AMC in this embodiment of the invention; Figure 6 The tensile strength test results of the polymer PPGTD-PDMS-IPDI-x-AMC in the embodiments of the present invention are shown below. Figure 7 The adhesion test results are for the polymer PPGTD-PDMS-IPDI-x-AMC in the embodiments of the present invention. Detailed Implementation

[0018] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0019] The materials used in the following experiments were: α,ω-aminopropyl-terminated polydimethylsiloxane (APT-PDMS) (Shanghai Maclean Biochemical Technology Co., Ltd.), isophorone diisocyanate (IPDI) (Shanghai Aladdin Reagent Co., Ltd.), 7-amino-4-methylcoumarin (AMC) (Shanghai Maclean Biochemical Technology Co., Ltd.), polypropylene glycol, tolyl-2,4-diisocyanate-terminated polymer (PPGTD) (Shanghai Maclean Biochemical Technology Co., Ltd.), tetrahydrofuran (THF) (Shanghai E. En Chemical Technology Co., Ltd.), and dibutyltin dilaurate (DBTDL) (Shanghai Maclean Biochemical Technology Co., Ltd.).

[0020] All tetrahydrofuran used in the experiment was dried after being dehydrated. α,ω-aminopropyl-terminated polydimethylsiloxane APT-PDMS needed to be placed in a vacuum drying oven at 110°C for 2 hours under vacuum conditions before use.

[0021] Example 1 A coumarin-modified copolymer is prepared by the following steps: (1) 2.3 g (1 mmol) of polypropylene glycol, tolyl-2,4-diisocyanate-terminated polymer PPGTD was dissolved in 20 mL of anhydrous tetrahydrofuran (THF), and then the solution was transferred to a 250 mL three-necked flask. The three-necked flask was pre-equipped with a magnetic stir bar and a reflux condenser, a nitrogen protection device and a constant pressure dropping funnel were set up. 1.75 g (1.75 mmol) of α,ω-aminopropyl-terminated polydimethylsiloxane (APT-PDMS) was dissolved in 10 mL of THF. The resulting solution was added to the constant pressure dropping funnel. The entire apparatus was evacuated and purged with nitrogen for oxygen removal. Nitrogen was then purged for 5 min. The dropping rate of the constant pressure dropping funnel was adjusted to 1 drop / 3-4 s, so that the tetrahydrofuran solution of APT-PDMS was added to the three-necked flask at a uniform rate within 30 min. After the addition was completed, the mixture was kept at 50 °C for 5 h. After the reaction was completed, the first mixture was obtained.

[0022] (2) Weigh 0.20 g (0.75 mmol) of isophorone diisocyanate (IPDI), dissolve it in 10 mL of dry tetrahydrofuran (THF), add the solution to a constant pressure dropping funnel, evacuate the reaction apparatus again and purge with nitrogen to remove oxygen, adjust the dropping rate to 1 drop / 3-4 s, so that the tetrahydrofuran solution of IPDI is added to the first mixture at a uniform rate within 45 min. After the addition is completed, raise the reaction temperature to 55 °C, and continue to stir the reaction at a constant temperature for 5 h under nitrogen protection and magnetic stirring. After the reaction is completed, the second mixture is obtained.

[0023] (3) Weigh 0.03 g (0.17 mmol) of 7-amino-4-methylcoumarin (AMC), dissolve it completely in 10 mL of dry tetrahydrofuran, and then add 10 μL of dibutyltin dilaurate (DBTDL). Add the solution to the constant pressure dropping funnel, and evacuate the reaction apparatus again and purge it with nitrogen to remove oxygen. Adjust the dropping rate to 1 drop / 3-4 s, and adjust the constant pressure funnel so that the AMC solution is added to the flask at a uniform rate within 30-35 min. After the addition is completed, keep the reaction at 60 °C for 8 h.

[0024] (4) After the reaction is completed, the excess tetrahydrofuran (THF) solvent in the reaction mixture is removed by rotary evaporation. Then, the reaction mixture treated by rotary evaporation is transferred to a polytetrafluoroethylene mold. The mold is placed in a vacuum drying oven at 60°C and dried in a vacuum environment for 48 hours to remove the residual solvent in the system and complete the curing process of the reactants. After the reaction is completed, a coumarin-modified polyurea silicone copolymer is obtained, named PPGTD-PDMS-IPDI-3-AMC.

[0025] Example 2 The difference between this embodiment and Example 1 is the molar ratio of α,ω-aminopropyl-terminated polydimethylsiloxane APT-PDMS to isophorone diisocyanate IPDI, wherein α,ω-aminopropyl-terminated polydimethylsiloxane APT-PDMS: isophorone diisocyanate IPDI = 1.5 mmol: 0.5 mmol. The rest of the process is the same as in Example 1, and the resulting copolymer is named PPGTD-PDMS-IPDI-2-AMC.

[0026] Example 3 The difference between this embodiment and Example 1 is the molar ratio of α,ω-aminopropyl-terminated polydimethylsiloxane APT-PDMS to isophorone diisocyanate IPDI, wherein α,ω-aminopropyl-terminated polydimethylsiloxane APT-PDMS: isophorone diisocyanate IPDI = 1.25 mmol: 0.25 mmol. The rest of the process is the same as in Example 1, and the resulting copolymer is named PPGTD-PDMS-IPDI-1-AMC.

[0027] Example 4 The difference between this embodiment and Example 1 is the molar ratio of α,ω-aminopropyl-terminated polydimethylsiloxane APT-PDMS to isophorone diisocyanate IPDI, wherein the ratio of α,ω-aminopropyl-terminated polydimethylsiloxane APT-PDMS to isophorone diisocyanate IPDI is 2 mmol: 1 mmol. The rest of the process is the same as in Example 1, and the resulting copolymer is named PPGTD-PDMS-IPDI-4-AMC.

[0028] The synthetic route of the above embodiments is as follows: Figure 1 As shown.

[0029] Compare with Example 1 The difference between this comparative example and Example 1 is that the polypropylene glycol-tolyl-2,4-diisocyanate-terminated polymer PPGTD is not added; the rest of the process is the same as in Example 1. The resulting copolymer is named PDMS-IPDI-AMC.

[0030] Test Example 1: Characterization by Proton Nuclear Magnetic Resonance (HNMR) Spectroscopy The copolymers prepared in Examples 1-4 were used as test samples and characterized using nuclear magnetic resonance (NMR) with deuterated dimethyl sulfoxide (DMSO-d6) as the reagent. The instrument parameters were set as follows: resonance frequency 400 MHz, 32 scans. The results are as follows. Figure 2 As shown.

[0031] Depend on Figure 2 It can be seen that the peak at 0.16 ppm (Ha) is the proton peak of -CH3 on PDMS (polydimethylsiloxane); the peaks at 0.32 ppm (Hb) and 1.12 ppm (Hd) are the proton peaks of -CH2- on PDMS; the peak at 0.65 ppm (Hc) is the proton peak of -CH3 on IPDI; the peak at 1.68 ppm (He) is the proton peak of -CH2- on cyclohexane on IPDI; the peak at 1.85 ppm (Hf) is the proton peak of -CH3 on phenyl in PPGTD; the peak at 2.76 ppm (Hg) is the proton peak of -CH3 on AMC; the peak at 2.87 ppm (Hh) is the proton peak of -CH2- on IPDI; the peaks at 3.71 ppm (Hj) and 3.96 ppm (Hj) are the proton peaks of -CH2- on PPGTD; and the peak at 5.88 ppm (Hc) is the proton peak of -CH2- on PPGTD. The peak at ppm (Hl) is the proton peak on the urea group after the reaction of PPGTD and PDMS; the peak at 6.17 ppm (Hm) is the proton peak of =CH- on AMC; the peak at 6.58 ppm (Hq) is the proton peak on the urea group after the reaction of IPDI and AMC; the peak at 7.16 ppm (Hn) is the proton peak of the phenyl group on PPGTD; and the peak at 8.63 ppm (Hp) is the proton peak of -NH- on AMC.

[0032] This proves that the AMC-grafted modified PPGTD-PDMS-IPDI-x-AMC polymer was successfully synthesized (x represents different sample numbers, namely 1, 2, 3, and 4).

[0033] Test Example 2: Diatom Removal Effect Test The removal effect on *Phaeodactylum tricornutum* (a representative marine fouling diatom) was determined.

[0034] The experiment selected *Phaeodactylum tricornutum*, a common marine algae, as the experimental subject. Before the experiment, 150 mL of artificial seawater was mixed with the culture medium and poured into a sterilized 250 mL Erlenmeyer flask. *Phaeodactylum tricornutum* inoculum was then inoculated and placed in a constant temperature incubator at 21±2°C, 4000 Lux light intensity, and 12 hours of alternating light and dark conditions. After 15 days of cultivation, the OD value of the algal solution was adjusted to 0.2 using fresh culture medium, which was used as the standard algal solution concentration for subsequent experiments.

[0035] The polymers obtained in Examples 1-4 and Comparative Example 1 were used as test samples. The test samples were dissolved in N,N-dimethylformamide solvent and then uniformly dropped onto the surface of a glass slide. After drying and curing, the samples were used for the experiment. Before use, the samples were sterilized by ultraviolet light irradiation. The samples were fixed in sterile beakers with hot melt adhesive, and then a pre-prepared standard concentration of algal solution was added until the samples were completely submerged in the solution. The beakers were sealed with sterile, breathable sealing film, and cultured under the same conditions. After 72 hours of culture, the sample surface was slowly rinsed with sterilized artificial seawater to remove any unattached diatoms. The number of diatoms on the sample surface was then observed and recorded using a microscope. Ten different areas of each sample were selected at the same magnification, and each sample had three parallel samples. Finally, the average value was calculated as the density of diatoms attached to the sample surface. p s。

[0036] The removal rate of diatoms was evaluated using the "water flow rinsing method". Samples still with diatoms attached were rinsed under a water flow of approximately 30 kPa for 5 minutes to simulate a real marine environment. The diatoms attached to the sample surface were then observed and recorded using a microscope according to the aforementioned method, and the diatom density after rinsing was calculated. p R The formula for calculating the diatom removal rate is as follows:

[0037] The results are as follows Figure 3 As shown, from Figure 3As can be seen, the polymer coatings PPGTD (terminated with polypropylene glycol and toluene-2,4-diisocyanate) and then modified by grafting AMC showed that the diatom removal rate of the resulting polymer coatings PPGTD-PDMS-IPDI-1-AMC, PPGTD-PDMS-IPDI-2-AMC, PPGTD-PDMS-IPDI-3-AMC, and PPGTD-PDMS-IPDI-4-AMC, compared with the polymer coating PDMS-IPDI-AMC (modified by directly grafting AMC onto PPGTD without the addition of polypropylene glycol and toluene-2,4-diisocyanate), all reached over 95%. This indicates that a large amount of diatoms were removed, demonstrating that the polymer coating can inhibit diatom adhesion to the surface and has good desorption performance for fouling caused by *Phaeodactylum tricornutum*.

[0038] Test Example 3: Test on the Removal Effect of Simulated Barnacles In the laboratory, simulated barnacles were used to replace real barnacles in the test. The coating’s resistance to adhesion of large marine fouling organisms was evaluated by measuring the removal strength of the simulated barnacles on the coating surface. A lower removal strength indicates that the coating has better resistance to adhesion of fouling organisms. The simulated barnacle removal test was conducted in accordance with ASTM D5618 (2011).

[0039] The polymers obtained in Examples 1-4 and Comparative Example 1 were used as test samples. The samples were first dissolved in N,N-dimethylformamide solvent, then uniformly dropped onto the surface of an epoxy resin board. After drying and curing, they were used for testing. Aluminum cylinders with a diameter of 10 mm and a height of 10 mm were used as simulated barnacles. The simulated barnacles were uniformly bonded to the dried polymer coating surface using a two-component epoxy resin adhesive. After being left at room temperature for seven days to allow the adhesive to fully cure, the tests were conducted. During the test, a thrust gauge (Es SH-Ⅱ-500N) was used to push the simulated barnacles at a uniform speed and horizontally to the polymer coating. The shear force when the simulated barnacles detached from the coating surface was recorded, and the removal strength was calculated. For each sample, five simulated barnacles were tested at different locations using the above steps, and the average value was taken as the final removal strength (to ensure experimental accuracy, all tests should be performed by the same operator). The results are as follows: Figure 4 As shown.

[0040] from Figure 4The results show that the removal strength of simulated barnacles on polymer coatings PPGTD-PDMS-IPDI-1-AMC, PPGTD-PDMS-IPDI-2-AMC, PPGTD-PDMS-IPDI-3-AMC, and PPGTD-PDMS-IPDI-4-AMC is 0.30 MPa or less, while the removal strength of PDMS-IPDI-AMC reaches 0.33 MPa. This indicates that the polymer coating with PPGTD end-capped with polypropylene glycol and tolyl-2,4-diisocyanate has better fouling release performance than that without it.

[0041] Test Example 4: Water Resistance Test When polymer coatings are used as antifouling coatings in the ocean, the effects of the external environment (the ability to withstand a series of physical and chemical damages caused by water penetration and immersion) need to be considered. The water resistance of the coating is evaluated by measuring the water absorption rate of the coating, so as to assess the coating's ability to resist damage and its service life in the marine environment over a long period of time.

[0042] The polymers obtained in Examples 1-4 and Comparative Example 1 were used as test samples. They were dissolved in N,N-dimethylformamide solvent and poured into polytetrafluoroethylene molds. The solvent was removed by drying under vacuum at 55°C for 48 hours. The dried resin was then formed into 1cm × 1cm rectangular samples, and the initial sample mass was recorded as m0. The samples were then immersed in beakers filled with deionized water for 1 day, 7 days, and 15 days. After immersion, the samples were removed, surface water droplets were wiped off, and the weight of the samples was recorded as m. t Each sample was tested in triplicate, and the average value was used to calculate the water absorption rate W. The calculation formula is as follows:

[0043] The results are as follows Figure 5 As shown, from Figure 5As can be seen, the PDMS-IPDI-AMC polymer coating had the highest water absorption rate at different soaking times, consistently exceeding 2.0%, while the PPGTD-PDMS-IPDI-1-AMC, PPGTD-PDMS-IPDI-2-AMC, PPGTD-PDMS-IPDI-3-AMC, and PPGTD-PDMS-IPDI-4-AMC polymer coatings all had water absorption rates below 2.0%. Among these, as the soaking time increased, the water absorption rates of the four polymer coatings (PPGTD-PDMS-IPDI-1-AMC, PPGTD-PDMS-IPDI-2-AMC, PPGTD-PDMS-IPDI-3-AMC, and PPGTD-PDMS-IPDI-4-AMC) gradually diverged. The water absorption rate of PPGTD-PDMS-IPDI-4-AMC remained the lowest and showed the least variation, indicating good water resistance.

[0044] Test Example 5 Tensile Property Test To evaluate the ability of the polymer of the present invention as an antifouling coating to withstand mechanical tensile stress in a marine environment, tensile properties of the PPGTD-PDMS-IPDI-x-AMC series coatings were tested in accordance with GB / T528-2009 using a JHY-10KN tensile testing machine manufactured by Xiamen Jinheyuan Technology Co., Ltd.

[0045] The polymers obtained in Examples 1-4 and Comparative Example 1 were used as test samples. Each sample was dissolved in dry tetrahydrofuran to prepare a 20 wt% solution, poured into a polytetrafluoroethylene mold, allowed to level naturally at 25°C, and then dried in a vacuum oven at 50°C for 48 hours to obtain a uniform film with a thickness of (0.50 ± 0.05) mm. Standard specimens (total length 75 mm, gauge length 25 mm, width 4 mm) of national standard type III were cut using a dumbbell-shaped cutter for later use. Test conditions: room temperature (23 ± 2) ℃, relative humidity (50 ± 5)%; tensile rate 10 mm / min, preload 0.1 N. At least 5 specimens were used in each group, and the average value was taken. The results are as follows: Figure 6 As shown.

[0046] from Figure 6 As can be seen, the tensile strength of the polymer coatings PPGTD-PDMS-IPDI-1-AMC, PPGTD-PDMS-IPDI-2-AMC, PPGTD-PDMS-IPDI-3-AMC, and PPGTD-PDMS-IPDI-4-AMC gradually increased from (5.0 ± 0.1) MPa to (6.5 ± 0.1) MPa, and the elongation at break increased from (370 ± 1) % to (550 ± 5) %, exhibiting good flexibility and mechanical strength.

[0047] Test Example 6: Coating Adhesion Performance Test For antifouling coatings, since they remove surface contaminants and organisms through the water shear force generated by the movement of ships, they need to form good adhesion to the substrate so that they are not easily detached under external forces. Therefore, strong adhesion is one of the essential conditions for polymer coatings.

[0048] The polymers obtained in Examples 1-4 and Comparative Example 1 were used as test samples. The samples were dissolved in N,N-dimethylformamide solvent and then uniformly dropped onto an iron sheet. The sheets were dried under vacuum at 55°C for 48 hours until the solvent completely evaporated before testing. The adhesion of the coating was analyzed using the pull-off method according to ATSM D4541-09, "Standard Test Method for Measuring Pull-Off Adhesion Strength of Coatings with Portable Adhesion Tester". A 20mm diameter aluminum test column was adhered to the coating surface with adhesive. After the adhesive had fully cured, a knife was used to cut through the cured adhesive and coating to the substrate along the edge of the test column. The test column was mounted on the adhesion tester, and the sample was placed flat on a stable table. A vertically upward force was then applied to the test column. The test results were judged based on the failure surface, and the maximum load was recorded (the test should be conducted at three different locations on the sample to ensure accuracy). The results are as follows: Figure 7 As shown.

[0049] from Figure 7 As can be seen, PDMS-PDI-AMC exhibited the lowest adhesion, approximately 1.25 MPa. Among the four samples with added PPGTD, the adhesion of the polymer coatings PPGTD-PDMS-PDI-1-AMC (PDMS=1.25 mmol), PPGTD-PDMS-PDI-2-AMC (PDMS=1.5 mmol), PPGTD-PDMS-PDI-3-AMC (PDMS=1.75 mmol), and PPGTD-PDMS-PDI-1-AMC (PDMS=2 mmol) showed a trend of first increasing and then decreasing with increasing PDMS content, reaching its maximum at PDMS=1.75 mmol, approximately 2.35 MPa. This is because the increased PDMS content leads to an increased urea group content in the polymer, and the urea groups combine with the active groups in the substrate to form hydrogen bonds, thus increasing adhesion. However, due to the increase in PDMS content, the molecular weight of the polymer increases. When the molecular weight increases to a certain extent, the number of entanglement points between polymer chains increases and the interaction force increases, which hinders the movement of polymer chains. Urea groups are difficult to combine with active groups on the substrate surface, thus reducing adhesion.

[0050] The above results show that the addition of PPGTD in this invention can improve the adhesion performance of the polymer coating, which can be firmly attached to the surface of the substrate and is not easy to detach under the action of external force, thus achieving a long-lasting anti-fouling effect.

[0051] In summary, the polymer obtained by adding PPGTD and then grafting coumarin functional groups can improve the dirt removal effect and mechanical properties of the antifouling coating, while also further improving its water resistance and adhesion properties. This can improve the overall performance of the polymer antifouling coating and has good application prospects.

[0052] Although the present invention has been described using the above preferred embodiments, it is not intended to limit the scope of protection of the present invention. Any changes and modifications made by those skilled in the art to the above embodiments without departing from the spirit and scope of the present invention shall still fall within the scope of protection of the present invention.

Claims

1. A coumarin-modified copolymer, characterized in that, The copolymer comprises an isocyanate-terminated polyether polyol polymer, α,ω-aminopropyl-terminated polydimethylsiloxane APT-PDMS, isophorone diisocyanate IPDI, and coumarin compounds, wherein the molar ratio of the isocyanate-terminated polyether polyol polymer, α,ω-aminopropyl-terminated polydimethylsiloxane APT-PDMS, isophorone diisocyanate IPDI, and coumarin compounds is 1:(1-2):(0.2-1):(0.1-0.2).

2. The coumarin-modified copolymer according to claim 1, characterized in that, The coumarin compound is 7-amino-4-methylcoumarin (AMC).

3. The coumarin-modified copolymer according to claim 1, characterized in that, The isocyanate-terminated polyether polyol polymer is polypropylene glycol, specifically the toluene-2,4-diisocyanate-terminated polymer PPGTD.

4. The method for preparing the coumarin-modified copolymer according to claim 1, characterized in that, Includes the following steps: (1) Dissolve the isocyanate-terminated polyether polyol polymer in tetrahydrofuran (THF) to obtain a first solution, dissolve the α,ω-aminopropyl-terminated polydimethylsiloxane (APT-PDMS) in tetrahydrofuran (THF) to obtain a second solution, add the second solution to the first solution dropwise at a rate of 1 drop / 3-4 s under nitrogen protection, and after the addition is complete, keep the temperature constant and react. After the reaction is complete, obtain the first mixture. (2) Dissolve isophorone diisocyanate (IPDI) in tetrahydrofuran (THF) to obtain a third solution. Add the third solution dropwise to the first mixture at a rate of 1 drop / 3-4 s under nitrogen protection. After the addition is completed, carry out a constant temperature reaction under nitrogen protection and magnetic stirring. After the reaction is completed, obtain a second mixture. (3) Dissolve coumarin compounds in tetrahydrofuran (THF), then add dibutyltin dilaurate (DBTDL) to obtain a fourth solution. Add the fourth solution to the second mixture at a rate of 1 drop / 3-4 s under nitrogen protection. After the addition is completed, react at a constant temperature. After the reaction is completed, obtain a third mixture. (4) After removing the excess tetrahydrofuran (THF) solvent from the third mixture, vacuum drying was performed to obtain a coumarin-modified polyurea organosilicon copolymer.

5. The method for preparing the coumarin-modified copolymer according to claim 4, characterized in that, In step (1), the uniform dripping time is 25-30 min; the constant temperature reaction temperature is 40-45℃ and the time is 4-7 h.

6. The method for preparing the coumarin-modified copolymer according to claim 4, characterized in that, In step (2), the uniform dripping time is 40-45 min, the constant temperature reaction temperature is 50-55℃, and the time is 4-7 h.

7. The method for preparing the coumarin-modified copolymer according to claim 4, characterized in that, In step (3), the uniform dripping time is 30-35 min, the constant temperature reaction temperature is 55-60℃, and the time is 6-10 h.

8. The method for preparing the coumarin-modified copolymer according to claim 4, characterized in that, In step (4), the vacuum drying temperature is 60-65℃ and the time is 44-48h.

9. The application of the coumarin-modified copolymer according to any one of claims 1-3 in marine antifouling coatings.

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