A titanium alloy pipeline marine antifouling system based on copper ion release capture mechanism and a construction method thereof

Abstract

The application belongs to the technical field of marine engineering antifouling, and particularly relates to a titanium alloy pipeline marine antifouling system based on a copper ion release and capture mechanism and a construction method thereof. The antifouling system comprises a titanium alloy pipeline main body, a copper alloy release source and an intelligent polymer brush modification layer grafted to the inner wall of the pipeline main body. The copper alloy release source and the titanium alloy pipeline main body form a galvanic couple in seawater medium to release copper ions, and the intelligent polymer brush modification layer comprises a pH-responsive polyacrylic acid main chain and covalently connected crown ether units. The application utilizes titanium alloy and copper alloy to realize self-driven and sustainable supply of copper ions; through a pH-responsive intelligent polymer brush, a dynamic interface with ion recognition and capture capability is constructed to realize "normal capture storage-fouling trigger release" of Cu 2+ , which does not require an external energy source and can realize on-demand and fixed-point release of antifouling agents, greatly improves the utilization efficiency, prolongs the antifouling life and significantly reduces the impact on the environment.

Description

Technical Field

[0001] This application belongs to the field of marine engineering antifouling technology, specifically relating to a titanium alloy pipeline marine antifouling system based on a copper ion release and capture mechanism and its construction method. Background Technology

[0002] Titanium alloys, due to their high specific strength, excellent corrosion resistance, and lightweight properties, have become a key material for high-performance marine pipeline systems. However, titanium alloys themselves do not possess active antifouling capabilities. In marine environments, barnacles, shellfish, algae, and other organisms easily adhere to the inner walls of their pipes, causing serious biofouling problems. This leads to increased flow resistance, reduced heat transfer efficiency, intensified localized corrosion, and even pipeline blockage, resulting in significant economic losses and safety risks.

[0003] Currently, applying antifouling coatings to titanium alloy surfaces is the most widely used and effective protective method. These coatings mainly rely on two mechanisms: one is chemically deterrent, such as copper- or tin-free polymer coatings, which inhibit biofouling through the slow release of antifouling agents; the other is physical barrier, such as super-slippery or low-surface-energy coatings, which make it difficult for organisms to adhere firmly by changing the surface energy or forming a lubricating layer.

[0004] However, the existing solution has the following drawbacks: Chemically-based antifouling coatings release antifouling agents in a passive and continuous process, making it difficult to control the release rate based on the level of fouling. Excessive release can negatively impact the marine ecosystem, while insufficient release leads to antifouling failure. Physically-based barrier coatings are prone to mechanical wear and chemical degradation under harsh environments such as turbulent seawater erosion and biological metabolic product corrosion, resulting in functional decline.

[0005] Furthermore, the adhesion between this type of coating and the passivation layer on the titanium alloy surface is usually weak, resulting in easy peeling and short service life. More seriously, the dense structure of traditional organic coatings may hinder the transport of dissolved oxygen to the titanium alloy substrate, interfering with the dynamic self-repair process of its surface passivation film, thereby inducing under-film corrosion and forming a vicious cycle of "anti-fouling failure - localized corrosion" that further threatens the long-term safety of the pipeline system. Summary of the Invention

[0006] The purpose of this application is to provide a marine antifouling system for titanium alloy pipelines and its construction method, to overcome the problems of short antifouling life, uncontrollable release of antifouling agents, poor environmental friendliness, and potential induction of underfilm corrosion in existing technologies. This application utilizes the electrical couple formed between titanium alloy and copper alloy in seawater to achieve copper ion (Cu) 2+ Self-driven and sustainable supply; by grafting pH-responsive smart polymer brushes onto the inner wall of titanium alloy pipes, a dynamic interface with ion recognition and capture capabilities is constructed, enabling the control of Cu... 2+The system employs a smart cycle of "normal capture and storage - contamination-triggered release." Requiring no external power source, this system enables on-demand, targeted release of the antifouling agent, significantly improving utilization efficiency, extending antifouling lifespan, and substantially reducing environmental impact. The technical solution of this application is as follows: This application provides a marine antifouling system for titanium alloy pipelines, comprising: A titanium alloy pipe body; A copper alloy release source is connected upstream of the titanium alloy pipe body to form an electrical couple with the titanium alloy pipe body in seawater medium, releasing copper ions (Cu) via anodic dissolution. 2+ ); A smart polymer brush modification layer is grafted onto the inner wall of the titanium alloy pipe body. The smart polymer brush modification layer comprises a pH-responsive polyacrylic acid (PAA) backbone and crown ether units covalently connected to the backbone. The intelligent polymer brush modification layer is configured such that: under normal seawater pH conditions, the polyacrylic acid backbone is in a swollen state, and the crown ether unit captures and stores copper ions released by the electrocouple pair; when microbial attachment causes a local pH decrease, the polyacrylic acid backbone turns into a contracted state, and the crown ether unit releases the stored copper ions, forming a targeted high-concentration copper ion region.

[0007] Furthermore, the copper alloy release source is a section of pure copper pipe, which is connected to the titanium alloy pipe body via flange connection or welding. Furthermore, the titanium alloy pipe marine antifouling system requires no external power source, and the release rate of copper ions is optimized by adjusting the anode-cathode area ratio of the titanium alloy pipe body and the copper alloy release source.

[0008] Furthermore, the crown ether unit is an amino derivative of benzo-18-crown-6 (B18C6Am).

[0009] Furthermore, the smart polymer brush modification layer is grafted onto the inner wall of the titanium alloy pipe body via surface-initiated atom transfer radical polymerization (SI-ATRP).

[0010] Furthermore, the intelligent polymer brush modification layer is grafted onto the inner wall of the titanium alloy pipe body through the following steps: Step 1, Pretreatment and hydroxylation activation: After polishing, cleaning and drying the inner wall surface of the titanium alloy pipe body, plasma treatment is performed with working gas containing argon and water vapor to obtain a hydroxylated surface; Step 2, Aminated silane modification: The hydroxylated surface is immersed in an alcohol-water mixed solvent containing 3-aminopropyltriethoxysilane (APTES) and reacted at 50-70°C for 0.5-2 hours to obtain an aminated surface; Step 3, Atom Transfer Radical Polymerization Initiator Grafting: The aminated surface is placed in an organic solution containing an acyl halide initiator, and an amidation reaction is carried out under low temperature conditions to introduce halogenated initiating groups onto the surface; Step 4: Surface-Initiated Atom Transfer Radical Polymerization to Construct Polymer Brushes: The surface grafted with halogenated initiating groups is placed in a polymerization reactor. Water is used as the polymerization medium, and acrylic acid (AA) monomer and crown ether functional monomer are added. The reaction is carried out at 60–70°C for 24–48 hours under inert gas protection to form a copolymer brush layer of polyacrylic acid and crown ether functional monomer. The molar ratio of the acrylic acid monomer to the benzo-18-crown-6 amino derivative monomer is 7:3.

[0011] Furthermore, in step one, the surface roughness after polishing is less than or equal to 200 nanometers; the cleaning is performed sequentially using acetone, anhydrous ethanol, and ultrapure water for ultrasonic cleaning. Furthermore, in step one, the ultrasonic cleaning time is 10-20 minutes, preferably 15 minutes; the cleaned sample is then dried, preferably by vacuum drying at 60°C. Further, in step one, the plasma treatment power is 150–250 watts, and the treatment time is 2–4 minutes. The plasma treatment uses argon gas carrying water vapor as the working gas. Optionally, the plasma treatment power is 200 watts, and the treatment time is 4 minutes. The plasma treatment uses argon gas carrying water vapor as the working gas.

[0012] Further, in step two, the hydroxylated surface is immersed in a mixed solvent of anhydrous ethanol and ultrapure water in a volume ratio of 3:1 to 5:1, and 0.5% to 2% of 3-aminopropyltriethoxysilane (APTES) is added, reacting at 50 to 70°C for 0.5 to 2 hours to obtain an amination surface. Optionally, the hydroxylated surface is immersed in a mixed solvent of anhydrous ethanol and ultrapure water in a volume ratio of 4:1, and 1% of 3-aminopropyltriethoxysilane (APTES) is added, reacting at 50 to 70°C for 0.5 to 2 hours to obtain an amination surface. The preferred reaction temperature is 60°C, and the preferred reaction time is 1 hour.

[0013] Furthermore, in step two, after the reaction is complete, the sample is rinsed with anhydrous ethanol and ultrapure water to remove unreacted or physically adsorbed silane molecules from the surface.

[0014] Further, in step three, the organic solution is a mixed solution of dichloromethane and triethylamine; the low-temperature condition is an ice-water bath at 0–5 degrees Celsius; and the acyl halide initiator is 2-bromoisobutyryl bromide (BiBB). Further, in step three, the amination-treated surface is placed in a mixed solution of dichloromethane and triethylamine, and 2-bromoisobutyryl bromide (BiBB) is added dropwise under 0–5 degrees Celsius ice-water bath conditions to carry out an amidation reaction, introducing bromination initiation groups onto the surface.

[0015] Further, in step three, the TA24@NH2 sample is placed in a mixed solution containing dichloromethane and triethylamine, and stirred under nitrogen protection in an ice-water bath at 0–5°C. Then, 1 mL of 2-bromoisobutyryl bromide (BiBB) is dissolved in 10 mL of anhydrous dichloromethane to prepare a dropping solution, which is added dropwise to the reaction system over 5–15 minutes. After the addition is complete, the ice-water bath is removed, and the reaction is allowed to proceed at room temperature for 1 hour. After the reaction is complete, the mixture is washed to obtain the final product. In the mixed solution, the volume ratio of dichloromethane to triethylamine is 75:4.5; in the dropping solution, the volume ratio of 2-bromoisobutyryl bromide (BiBB) to anhydrous dichloromethane is 1 mL:10 mL.

[0016] Furthermore, in step four, the crown ether functional monomer is an amino derivative of benzo-18-crown-6 (B18C6Am); the polymerization reaction is carried out in the presence of a catalytic system comprising cuprous bromide (CuBr) and 2,2'-bipyridine (bpy).

[0017] Further, in step four, the surface grafted with brominated initiating groups is placed in a polymerization reaction vessel, ultrapure water is used as the polymerization medium, and after deoxygenation treatment by purging with inert gas, acrylic acid (AA) monomer and benzo-18-crown-6 amino derivative (B18C6Am) are added, followed by a catalytic system containing cuprous bromide (CuBr) and 2,2'-bipyridine (bpy), and deoxygenation treatment is continued by purging with inert gas. The reaction is carried out at 60-70°C for 24-48 hours under inert gas protection to form a random copolymer brush layer of polyacrylic acid and benzo-18-crown-6 amino derivative. The preferred time for purging oxygen with inert gas is 20 minutes; the polymerization reaction is preferably carried out at 65°C for 36 hours; in the catalytic system, the amounts of cuprous bromide (CuBr) and 2,2'-bipyridine (bpy) are determined according to the total molar amount of the monomers, and the molar ratio of each component is AA: B18C6Am:CuBr:bpy = 7:3:8:22.

[0018] Furthermore, after polymerization, the sample is repeatedly washed with ethanol and ultrapure water, preferably combined with ultrasonic cleaning, to remove residual homopolymer, unreacted monomers and catalyst.

[0019] Furthermore, in the intelligent polymer brush modified layer, the polyacrylic acid (PAA) backbone contains a large number of ionizable carboxyl groups, and its chain conformation undergoes a reversible transformation with pH changes: it is in a swollen state under neutral conditions (pH≈8) and transforms into a contracted state under acidic conditions; the crown ether unit is effective against copper ions (Cu... 2+ It has specific high affinity and can form stable host-guest complexes.

[0020] Furthermore, the intelligent polymer brush modification layer is configured such that, under non-fouling conditions (normal seawater pH≈8), the polymer brush is in a swollen state, and the crown ether units efficiently capture Cu released by the galvanic effect. 2+ An "ion pool" is formed at the tube wall interface, reducing ineffective loss; when microbial attachment forms a biofilm leading to local microenvironment acidification (pH decrease), the polymer brush changes from swelling to contraction, causing crown ether and Cu... 2+ The binding constant decreases significantly, triggering rapid ion release and the formation of high-concentration Cu at the fouling site. 2+ The zone achieves targeted antifouling; after the fouling is removed, the pH recovers, the polymer brush re-swells and regains its capture capacity, completing the intelligent cycle.

[0021] This application also provides a method for constructing the above-mentioned titanium alloy pipeline marine antifouling system, including the following steps: Provide a titanium alloy pipe body and a copper alloy release source, and connect the copper alloy release source upstream of the titanium alloy pipe body; The inner wall of the titanium alloy pipe body is subjected to hydroxylation activation treatment; An amino-modified silane layer and an atom transfer radical polymerization initiator layer are sequentially grafted onto the inner wall after hydroxylation activation. Using acrylic acid monomers and crown ether functional monomers as comonomers, the smart polymer brush modification layer is formed on the inner wall of the titanium alloy pipe body by surface-initiated atom transfer radical polymerization.

[0022] Compared with the prior art, this application has the following advantages: This application overcomes the problems of short antifouling life, uncontrollable antifouling agent release, poor environmental friendliness, and potential induction of underfilm corrosion in existing technologies. It utilizes an electrical couple formed between titanium alloy and copper alloy in seawater to achieve copper ion (Cu) 2+ Self-driven and sustainable supply; by grafting pH-responsive smart polymer brushes onto the inner wall of titanium alloy pipes, a dynamic interface with ion recognition and capture capabilities is constructed, enabling the control of Cu... 2+The system employs a smart cycle of "normal capture and storage - fouling-triggered release." Under normal seawater pH conditions, the polymer brushes of the antifouling system provided in this application swell, and the crown ether captures and stores copper ions to form an ion pool. When microbial attachment causes a local pH decrease, the polymer brushes contract, triggering a rapid release of copper ions, achieving targeted antifouling. This system requires no external energy source, enabling on-demand, targeted release of the antifouling agent, greatly improving utilization efficiency, extending antifouling lifespan, and significantly reducing environmental impact. Attached Figure Description

[0023] Figure 1 This is a structural schematic diagram of the titanium alloy pipeline marine antifouling system of this application.

[0024] Figure 2 The diagram shows the principle of copper-titanium galvanic corrosion and the copper ion release rate. (a) is a schematic diagram of the principle of galvanic corrosion, and (b) is a comparison diagram of the copper ion release rate.

[0025] Figure 3 Schematic diagram illustrating the working principle of the intelligent polymer brush coating layer for anti-fouling on titanium alloy surfaces.

[0026] Figure 4 The Fourier transform infrared (FT-IR) spectrum of the smart polymer brush modified layer on the titanium alloy surface.

[0027] Figure 5 A graph showing the copper ion capture (pH=8)-release (pH=4.5) cycle of a smart polymer brush-modified layer on a titanium alloy surface under varying pH conditions.

[0028] Figure 6 Figure 1 shows the results of the marine hanging plate test for different samples. (a) is the untreated titanium plate of Comparative Example 1, (b) is the sample without copper alloy release source of Comparative Example 2, and (c) is the titanium plate grafted with smart polymer brush of Example 1.

[0029] Figure 7 Fluorescence images and adhesion rate data of Pseudomonas aeruginosa on different titanium alloy surfaces; Figure 8 Fluorescence images and adhesion rate data of *Phaeodactylum tricornutum* on different titanium alloy surfaces; Figure 9 Cu in TA24@PAB samples prepared with different monomer ratios at different initial concentrations 2+ Data graph of capture (adsorption) rate per unit area.

[0030] Figure 10 Cu content of TA24@PAB samples prepared with different monomer ratios under different pH conditions 2+ Release rate data per unit area.

[0031] Reference numerals: 100, titanium alloy pipe body; 200, copper alloy release source; 300, smart polymer brush finishing layer. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be described clearly and completely below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0033] This application also provides the following embodiments and comparative examples: Example 1 (TA24@PAB-Cu) This embodiment provides a marine antifouling system for titanium alloy pipelines and its construction method.

[0034] I. System Composition like Figure 1 As shown, the marine antifouling system for titanium alloy pipelines in this embodiment includes: a titanium alloy pipeline body 100 (made of TA24 titanium alloy), a copper alloy release source 200 (made of copper, T2 pipe section) connected upstream via a flange, and a smart polymer brush decoration layer 300 grafted onto the inner wall of the titanium alloy pipeline body 100.

[0035] like Figure 2 As shown in (a), the titanium alloy and copper alloy form an electrical couple in seawater, with the titanium alloy as the cathode and the copper alloy as the anode. The copper alloy, acting as the anode, preferentially dissolves, continuously releasing copper ions (Cu). 2+ ).like Figure 2 As shown in (b), this galvanocoupler effect can significantly increase the copper ion release rate.

[0036] II. Construction of the Smart Polymer Brush Modification Layer 300 like Figure 3 As shown, the working principle of the smart polymer brush modified layer 300 is as follows: Under normal conditions (normal seawater pH≈8), the polyacrylic acid (PAA) backbone is in a swollen state, and the crown ether unit captures and stores Cu released by the galvanic couple. 2+ An "ion pool" forms at the tube wall interface; when microorganisms attach and form a biofilm, causing local microenvironment acidification (pH decrease), the polyacrylic acid backbone transforms into a contracted state, and the crown ether units release the stored Cu. 2+ High concentrations of Cu are formed at the fouling points. 2+ The zone achieves targeted antifouling; after the fouling is removed, the pH recovers, the polymer brush re-swells and regains its capture capacity, completing the intelligent cycle.

[0037] The specific construction steps of the smart polymer brush modification layer 300 in this embodiment are as follows: Pretreatment and hydroxylation activation: The surface of TA24 titanium alloy was polished with sandpaper to a roughness Ra≤200nm. The polished sample was then ultrasonically cleaned sequentially with acetone, anhydrous ethanol, and ultrapure water for 15 minutes each, and vacuum dried at 60℃ for later use. The dried sample was then placed in a plasma treatment device, using argon gas carrying water vapor as the working gas, and treated at a power of 200W for 4 minutes to obtain a hydroxylated surface, denoted as TA24@OH.

[0038] Aminated silane modification: A mixed solvent of anhydrous ethanol and ultrapure water at a volume ratio of 4:1 was prepared, and 1% (by volume) of 3-aminopropyltriethoxysilane (APTES) was added. The TA24@OH sample was immersed in the above solution, mixed under stirring at room temperature, and then heated to 60°C for 1 hour. After the reaction was completed, the sample was rinsed with anhydrous ethanol and ultrapure water to obtain the aminated surface, denoted as TA24@NH2.

[0039] Atom transfer radical polymerization initiator grafting: A TA24@NH2 sample with a surface area of ​​2 cm × 2 cm was placed in a mixed solution containing 75 mL of dichloromethane and 4.5 mL of triethylamine, and stirred under nitrogen protection in an ice-water bath at 0–5 °C. Then, 1 mL of 2-bromoisobutyryl bromide (BiBB) was dissolved in 10 mL of anhydrous dichloromethane, and this solution (anhydrous dichloromethane containing BiBB) was added dropwise to the reaction system over 10 minutes. After the addition was complete, the ice-water bath was removed, and the reaction was allowed to proceed at room temperature for 1 hour. After the reaction was complete, the sample was washed to obtain the initiator-modified sample, denoted as TA24@Br.

[0040] Note: The grafting density of amino groups can be calculated after preparing TA24@NH2, which is approximately 0.5 nmol / cm³. 2 Up to 5 nmol / cm 2 The amount of amino grafting can be estimated from the surface area of ​​the TA24@NH2 sample. In this embodiment, the molar amount of BiBB added was far excess to ensure that all surface amino groups could participate in the reaction.

[0041] Surface-initiated atom transfer radical polymerization to construct a polymer brush: The TA24@Br sample prepared in the above steps was placed in a polymerization reaction vessel, 50 mL of ultrapure water was added, and nitrogen gas was purged for 20 minutes to remove oxygen. Acrylic acid (AA) monomer and benzo-18-crown-6 amino derivative monomer (B18C6Am) were added, and nitrogen purging continued to remove oxygen. Cuprous bromide (CuBr) and 2,2'-bipyridine (bpy) catalytic system were added, and the reaction was carried out at 65 °C for 36 hours under nitrogen protection. After the reaction was completed, the sample was ultrasonically cleaned with ethanol and ultrapure water in sequence to obtain the smart polymer brush modified layer 300, denoted as TA24@PAB.

[0042] The composition includes 0.05 mL of acrylic acid (AA) monomer, 0.12 g of benzo-18-crown-6 amino derivative monomer (B18C6Am), 0.12 g of cuprous bromide (CuBr), and 0.36 g of 2,2'-bipyridine (bpy). The molar ratio of AA:B18C6Am:CuBr:bpy is 7:3:8:22.

[0043] Comparative Example 1 (Untreated titanium plate TA24) Compared to untreated TA24 titanium alloy plates, under the same marine conditions, after 30 days, the surface of the untreated plates was covered with large fouling organisms such as barnacles and algae, indicating poor antifouling performance.

[0044] Comparative Example 2 (No copper alloy release source: TA24@PAB) This comparative example is basically the same as Example 1, except that: no copper alloy release source is set, that is, the upstream of the titanium alloy pipe body is not connected to the copper alloy pipe section, and only the inner wall of the titanium alloy pipe body is grafted with the same smart polymer brush modification layer (PAB).

[0045] Comparative Example 3 (only modified up to the aminosilane stage: TA24@NH2) This comparative example is basically the same as Example 1, except that the construction of the smart polymer brush modified layer only proceeds to step two, aminosilane modification. That is, the sample surface is only modified with an aminosilane layer (TA24@NH2), without subsequent initiator grafting and ATRP polymerization. Therefore, there is no polymer brush on the surface.

[0046] Performance tests of Examples 1-3 and Comparative Examples Structural characterization: The TA24@PAB surface was characterized using Fourier transform infrared spectroscopy (FT-IR), and the results are as follows: Figure 4 As shown, the TA24@PAB sample (blue) constructed with a poly(AA-co-B18C6Am) functional polymer brush via surface-initiated ATRP polymerization exhibits a series of characteristic peaks corresponding to the functional polymer structure, confirming the successful construction of the pH-responsive polymer brush: 2960 cm⁻¹ -1 The strong absorption peak is attributed to the CH stretching vibrations of the polymer backbone and saturated alkyl groups in the side chains. The peak intensity and shape show significant changes compared to the TA24@Br sample, corresponding to the successful growth of the polymer chain. (1259 cm⁻¹) -1 The characteristic peak at 1102 cm⁻¹ is attributed to the asymmetric stretching vibration of Ar-OR in the benzo[18-crown-6] structure. -1 The characteristic peaks at 1700 cm⁻¹ correspond to the asymmetric stretching vibrations of the aliphatic COC bonds in the crown ether ring. These peaks are specific to the B18C6Am monomer, confirming the successful participation of the crown ether functional monomer in the polymerization.-1 The broad absorption peaks nearby correspond to the C=O stretching vibrations of the carboxyl group -COOH of the acrylic acid unit and the amide bond of the B18C6Am unit, confirming the successful copolymerization of acrylic acid and B18C6Am monomers.

[0047] pH response reversibility: TA24@PAB samples were alternately immersed in solutions with pH=8 and pH=4.5, and the capture and release of copper ions were measured. Figure 5 As shown, after 20 pH cycles, the sample still maintained excellent Cu content. 2+ Capture-release reversibility.

[0048] Anti-fouling test: Sea-based hanging plate test: Untreated titanium plates and TA24@PAB samples were simultaneously suspended in the sea and observed after immersion for 30 days.

[0049] The results of Comparative Example 1 (TA24) are as follows Figure 6 As shown in (a), a large number of algae and barnacles were attached to the surface of the untreated titanium plate in Comparative Example 1. The results of Comparative Example 2 (TA24@PAB) are as follows Figure 6 As shown in (b), although the surface of the sample was improved compared to the untreated titanium plate, it still had a lot of barnacles and algae attached, and the anti-fouling effect was significantly worse than that of Example 1. The reason for this is that there is no copper alloy release source, so copper ions cannot be continuously provided. Relying solely on the polymer brush itself, which does not have a source of copper ions, an effective "capture-store-release" cycle cannot be formed.

[0050] The results are as follows Figure 6 As shown in (c), the titanium plate of the grafted smart polymer brush in Example 1 showed only slight algae attachment and no large fouling organisms.

[0051] Laboratory antifouling test - for antibacterial and antialgal (typical marine Gram-negative bacteria Pseudorabialis, typical marine single-celled diatoms Phaeodactylum tricornutum) antifouling test: Adhesion of *Pseudomonas alterniflora* on different titanium alloy surfaces: Test results are as follows Figure 7 As shown, where, Figure 7 (a) is a bare titanium alloy sheet, i.e., Comparative Example 1 (TA24). Figure 7 (b) is an aminated titanium alloy sheet, i.e., Comparative Example 3 (TA24@NH2). Figure 7 (c) is a titanium alloy sheet for grafting polymer brushes, i.e., Comparative Example 2 (TA24@PAB). Figure 7 (d) is a titanium alloy sheet after copper ions are captured by a grafted polymer brush, i.e., Example 1 (TA24@PAB-Cu). A large number of fluorescently labeled bacteria were visible on the surface of the unmodified TA24 bare slide, with an adhesion coverage of 21.43±2.28%, indicating the most severe adhesion situation. The bacterial adhesion on the surface of the amination-modified TA24@NH2 sample decreased, with the adhesion coverage rate dropping to 13.36±2.10%; the bacterial adhesion on the surface of the TA24@PAB sample with the constructed responsive polymer brush was further reduced, with the adhesion coverage rate being only 7.99±1.31%; Only sporadic bacterial distribution was observed on the surface of the TA24@PAB-Cu sample loaded with copper ions, with an adhesion coverage rate as low as 1.38±0.31%.

[0052] According to the anti-adhesion efficiency formula, the anti-adhesion efficiencies of TA24@NH2, TA24@PAB and TA24@PAB-Cu samples against Pseudomonas aeruginosa were 37.64%, 62.70% and 93.57%, respectively.

[0053] Adhesion of *Phaeodactylum triangularis* to different titanium alloy surfaces: Test results are as follows Figure 8 As shown, where, Figure 8 (a) is a bare titanium alloy sheet, i.e., Comparative Example 1 (TA24). Figure 8 (b) is an aminated titanium alloy sheet, i.e., Comparative Example 3 (TA24@NH2). Figure 8 (c) is a titanium alloy sheet for grafting polymer brushes, i.e., Comparative Example 2 (TA24@PAB). Figure 8 (d) is a titanium alloy sheet after copper ions are captured by a grafted polymer brush, i.e., Example 1 (TA24@PAB-Cu). A large number of fluorescently labeled algal cells were visible on the surface of the unmodified TA24 sheet, with an attachment coverage of 15.21±3.90%, and the attachment of diatoms was the most significant. The amount of algal cells attached to the surface of the amination-modified TA24@NH2 sample decreased significantly, with the attachment coverage rate dropping to 9.87±1.11%; the amount of algal cells attached to the surface of the TA24@PAB sample grafted with the responsive polymer brush was further reduced, with the attachment coverage rate being only 5.00±0.37%. Only a few scattered algal cells were observed on the surface of the TA24@PAB-Cu sample loaded with copper ions, with an adhesion coverage rate as low as 1.48±0.54%.

[0054] According to the anti-adhesion efficiency formula, the anti-adhesion efficiencies of TA24@NH2, TA24@PAB and TA24@PAB-Cu samples against *Phaeodactylum tricornutum* were 35.10%, 67.12% and 90.25%, respectively.

[0055] The specific antifouling effects are summarized in Table 1 below: Table 1 Statistical Table of Results

[0056] In addition, comparative examples were designed where the amount of crown ether functional monomer used was not within the specified range: Comparative Example 4 (the amount of crown ether functional monomer used is not limited) This comparative example is basically the same as Example 1, except that the molar ratio of each component AA: B18C6Am: CuBr: bpy is 9:1:8:22. Specifically, the total molar amount of acrylic acid (AA) monomer and benzo-18-crown-6 amino derivative monomer (B18C6Am) remains unchanged.

[0057] Comparative Example 5 (the amount of crown ether functional monomer used is not limited) This comparative example is basically the same as Example 1, except that the molar ratio of each component AA: B18C6Am: CuBr:bpy is 8:2:8:22. Specifically, the total molar amount of acrylic acid (AA) monomer and benzo-18-crown-6 amino derivative monomer (B18C6Am) remains unchanged.

[0058] Comparative Example 6 (The amount of crown ether functional monomer used is not limited) This comparative example is basically the same as Example 1, except that the molar ratio of each component AA: B18C6Am: CuBr:bpy is 6:4:8:22. Specifically, the total molar amount of acrylic acid (AA) monomer and benzo-18-crown-6 amino derivative monomer (B18C6Am) remains unchanged.

[0059] Experiments were conducted on the samples from Examples 4 and 6 and Comparative Examples 4-6: Cu at different initial concentrations 2+ Experiments on capture (adsorption) rate per unit area, Cu under different pH conditions 2+ The results of the release rate per unit area experiment are as follows: like Figure 9-10 As shown, based on the above Example 1 and Comparative Examples 4-6, four groups of experiments with different monomer feed ratios were designed. The samples were named TA24@PAB-X:Y, where X:Y is the molar ratio of AA to B18C6Am. The four groups of samples (Example 1 and Comparative Examples 4-6) were TA24@PAB-7:3, TA24@PAB-9:1, TA24@PAB-8:2, and TA24@PAB-6:4, respectively. Subsequently, its ability to capture copper ions at different concentrations (pH=8) and its ability to release copper ions at different pH values ​​were studied.

[0060] Analysis of the data in the graph shows that the ability to capture copper ions increases proportionally with the increase of the crown ether ratio. However, as the crown ether ratio increases, the proportion of acrylic acid decreases, affecting its pH response performance and further impacting its copper ion release capacity (from which the optimal ratio for capturing and releasing copper ions can be selected). The ratio of AA to B18C6Am is used to regulate the copper ion capture in the polymer brush. 2+ The core parameters of the release behavior. Combining adsorption and release performance, TA24@PAB-7:3 simultaneously possesses highly efficient adsorption and enrichment capabilities with stable and controllable release. The effects of comparative examples 4-6 are significantly worse.

[0061] This application's solution summary and comparative analysis of embodiments are presented in a comparative example. The core design concept of this application lies in constructing a marine antifouling system for titanium alloy pipelines, consisting of a "self-driven ion source, intelligent response interface, and closed-loop circulation." Specifically: I. Dual-function unit of intelligent polymer brush This polymer brush has a dual-functional unit: pH-responsive backbone: composed of polymers such as polyacrylic acid (PAA) containing a large number of ionizable carboxyl groups, its chain conformation undergoes a reversible transformation with pH change—it is in a swollen state under neutral conditions (pH≈8) and turns into a contracted state under acidic conditions; Ion-trapping functional unit: a crown ether unit covalently linked to the main chain (such as an amino derivative of benzo-18-crown-6, B18C6), for Cu 2+ It has specific high affinity and can form stable host-guest complexes.

[0062] II. System Working Principle (e.g.) Figure 3 (As shown) Normal capture and storage (no fouling, pH≈8): Under normal seawater pH conditions, the polymer brush is in a swollen state, and the crown ether unit efficiently captures Cu released by the galvanic effect. 2+ An "ion pool" is formed at the pipe wall interface, reducing ineffective loss.

[0063] Fouling Triggering and Smart Release (Biofilm Formation, pH Decrease): Microbial attachment and biofilm formation lead to local microenvironment acidification, causing the polymer brush to swell and then contract, triggering the reaction of crown ethers and Cu. 2+ The binding constant decreases significantly, triggering rapid ion release and the formation of high-concentration Cu at the fouling site. 2+ The area is designed to achieve targeted pollution prevention.

[0064] Function reset: After the contamination is removed, the pH is restored, the polymer brush re-swells and regains its capture capacity, completing the intelligent cycle.

[0065] III. Structural Verification and Performance The chemical structure of the smart interface was verified by Fourier transform infrared spectroscopy (FT-IR). Figure 4 ), grafted surface at 1720 cm -1 The presence of characteristic absorption peaks for polyacrylic acid carboxyl groups and crown ethers at various locations confirms successful grafting of the polymer brush. For example... Figure 5 As shown, the modified layer retains excellent Cu content even after 8 pH cycles. 2+ The capture-release mechanism exhibits reversibility and good long-term stability. (Real-sea hanging plate test) Figure 6 The antifouling performance of the system was further verified: compared with the large amount of algae and barnacles attached to the surface of the untreated titanium plate in Comparative Example 1, the titanium plate of the grafted smart polymer brush in Example 1 of this application showed only slight algae attachment after being soaked in seawater for 30 days, with no large fouling organisms, and the antifouling effect was significant.

[0066] IV. Comparison Analysis of Examples and Comparative Examples Comparison of Example 1 (TA24@PAB-Cu) and Comparative Example 1 (untreated titanium plate TA24) In Comparative Example 1, no antifouling measures were taken. After 30 days, the surface of the marine siding was covered with large fouling organisms such as barnacles and algae. The coverage rate for *Pseudomonas aeruginosa* was 21.43±2.28%, and the coverage rate for *Phaeodactylum tricornutum* was 15.21±3.90%. In contrast, Example 1, through the synergistic effect of the copper alloy release source and the intelligent polymer brush modification layer, showed only slight algae attachment and no large fouling organisms after 30 days. The coverage rate for *Pseudomonas aeruginosa* decreased to 1.38±0.31%, and the coverage rate for *Phaeodactylum tricornutum* decreased to 1.48±0.54%. This indicates that the overall technical solution of this application has a significant antifouling effect.

[0067] Comparison of Example 1 and Comparative Example 2 (no copper alloy release source, PAB only) Comparative Example 2 did not use a copper alloy release source, only grafted polymer brushes (TA24@PAB). Although the sea-hanging plate showed some improvement compared to the untreated titanium plate after 30 days, it still had a significant amount of barnacles and algae attached; the coverage rate for *Pseudomonas aeruginosa* was 7.99±1.31%, and the coverage rate for *Phaeodactylum tricornutum* was 5.00±0.37%, both significantly higher than in Example 1. This indicates that the copper alloy release source provides a continuous source of Cu. 2+ The necessary components of the source cannot form an effective "capture-store-release" cycle by polymer brushes alone.

[0068] Comparison of Example 1 and Comparative Example 3 (modified with aminosilane only, TA24@NH2) Comparative Example 3 only underwent aminosilane modification, without a polymer brush on the surface. Its coverage rate for *Pseudomonas aeruginosa* was 13.36 ± 2.10%, and for *Phaeodactylum tricornutum*, it was 9.87 ± 1.11%, showing limited improvement compared to the untreated titanium plate. In the actual marine test, a large amount of fouling organisms still adhered to the surface. This indicates that a complete polymer brush structure (including initiator grafting and ATRP polymerization) is crucial for achieving ion trapping and intelligent release; interruption of this intermediate step leads to a significant decrease in antifouling function.

[0069] Comparison of Example 1 with Comparative Examples 4-6 (different AA:B18C6Am monomer ratios) Comparative Examples 4-6 used AA:B18C6Am molar ratios of 9:1, 8:2, and 6:4, respectively, to compare with the 7:3 ratio in Example 1. Figure 9-10 As shown: Cu 2+ Adsorption capacity: The adsorption rate increases with the increase of crown ether ratio (6:4>7:3>8:2>9:1), but an excessively high crown ether ratio will reduce the proportion of acrylic acid.

[0070] Cu 2+ Release capacity (pH responsiveness): When the acrylic acid ratio is too low (6:4), the pH responsive contraction behavior of the polymer brush is inhibited, and the release rate and sensitivity decrease.

[0071] Overall performance: Example 1 (7:3) achieves the best balance between adsorption and release, while possessing both efficient enrichment and stable, controllable release capabilities; Comparative Examples 4-6, due to deviations from the preferred ratio, exhibit significantly poorer antifouling effects. This demonstrates that the monomer ratio is the core parameter for regulating intelligent antifouling performance, and the preferred 7:3 molar ratio of this application achieves the best overall antifouling effect.

[0072] Explanation of the intermediate states between Comparative Example 2 and Comparative Example 3 Comparative Examples 2 (without copper source) and 3 (without polymer brush) further verify that the two core elements of this application, "copper alloy release source + intelligent polymer brush," are indispensable. Having only a polymer brush without a copper source (Comparative Example 2) cannot provide a continuous Cu release. 2+ Having only a copper source without a polymer brush (Comparative Example 3) makes it impossible to capture and release ions on demand, and neither can achieve the excellent antifouling level of Example 1.

[0073] Overall Conclusion The above comparison shows that this application uses a "copper alloy release source (self-driven Cu)" 2+The synergistic effect of the "supply" and the "pH-responsive crown ether functionalized polymer brush (intelligent capture-storage-release)" achieves efficient, intelligent, and long-lasting antifouling of titanium alloy pipelines in marine environments. Among these key technical features are the monomer ratio (AA:B18C6Am=7:3), the complete polymer brush grafting process, and the setting of the copper alloy release source; each element is interdependent and indispensable. Comparative examples 1-6 verify the necessity and rationality of each key feature in this technical solution from different perspectives.

[0074] In summary, the design concept and beneficial effects of this application Design concept: By utilizing the potential difference between titanium alloy and copper alloy in seawater, a macroscopic electrode pair is constructed, using the copper alloy as a consumable anode to achieve Cu 2+ It is self-driven and continuously releases power without requiring an external power source.

[0075] pH-responsive polyacrylic acid (PAA) backbones were grafted onto the inner wall of a titanium alloy via surface-initiated atom transfer radical polymerization (SI-ATRP) and covalently linked to Cu. 2+ Crown ether units with specific high affinity (such as amino derivatives of benzo-18-crown-6) form a smart polymer brush modified layer.

[0076] Based on the local microenvironment pH changes caused by biofouling, a closed-loop intelligent antifouling cycle is achieved: "normal capture and storage (pH≈8, swelling) → fouling-triggered release (pH decrease, shrinkage) → functional reset (pH recovery)".

[0077] Beneficial effects: Long-lasting self-driving: The thermocouple provides continuous Cu 2+ The source avoids the rapid depletion of traditional coating antifouling agents; the "ion pool" function of the polymer brush further extends the effective antifouling cycle (only slight algae were observed on the actual sea cladding after 30 days).

[0078] Intelligent on-demand release: Triggered by pH changes in the fouling microenvironment, Cu... 2+ Targeted and precise release greatly improves utilization efficiency and reduces environmental emissions.

[0079] Environmentally friendly: No toxic antifouling agents (such as organotin, cuprous oxide), Cu 2+ The release is autonomously regulated by the polluted state, resulting in minimal ecological impact.

[0080] No risk of under-film corrosion: The polymer brush has a loose, hydrophilic brush-like structure that does not hinder dissolved oxygen transport and does not affect the self-repair of the titanium alloy passivation film, thus eliminating the under-film corrosion problem of traditional organic coatings from the root.

[0081] Strong bonding: covalent grafting and anchoring (APTES silanization + initiator grafting + ATRP polymerization), not easy to peel off, and long service life.

[0082] Parameters are controllable: There is an optimal range for the amount of crown ether used, and the optimal range of this application ensures the best antifouling effect.

[0083] Finally, it should be noted that: B18C6Am material and its preparation method are existing technologies; for specific sources, please refer to [link / reference needed]. J. Phys. Chem. B 2008,112, 4, 1112–1118.

[0084] The specific parameters or some commonly used reagents or raw materials in the above embodiments are specific embodiments or preferred embodiments under the concept of this application, and are not intended to limit them; those skilled in the art can make adaptive adjustments within the concept and protection scope of this application.

[0085] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A marine antifouling system for titanium alloy pipelines, characterized in that, include: A titanium alloy pipe body; A copper alloy release source is connected upstream of the titanium alloy pipe body to form an electrical couple with the titanium alloy pipe body in seawater medium to release copper ions by anodic dissolution. A smart polymer brush modification layer is grafted onto the inner wall of the titanium alloy pipe body. The smart polymer brush modification layer comprises a pH-responsive polyacrylic acid backbone and crown ether units covalently connected to the backbone. The intelligent polymer brush modification layer is configured such that: under normal seawater pH conditions, the polyacrylic acid backbone is in a swollen state, and the crown ether unit captures and stores copper ions released by the electrocouple pair; when microbial attachment causes a local pH decrease, the polyacrylic acid backbone turns into a contracted state, and the crown ether unit releases the stored copper ions, forming a targeted high-concentration copper ion region.

2. The marine antifouling system for titanium alloy pipelines according to claim 1, characterized in that, The copper alloy release source is a section of copper pipe, which is connected to the titanium alloy pipe body via flange connection or welding.

3. The marine antifouling system for titanium alloy pipelines according to claim 1, characterized in that, The crown ether unit is an amino derivative of benzo-18-crown-6.

4. The marine antifouling system for titanium alloy pipelines according to claim 1, characterized in that, The intelligent polymer brush modification layer is grafted onto the inner wall of the titanium alloy pipe body through surface-initiated atom transfer radical polymerization.

5. The marine antifouling system for titanium alloy pipelines according to claim 4, characterized in that, The intelligent polymer brush modification layer is grafted onto the inner wall of the titanium alloy pipe body through the following steps: S1. Pretreatment and hydroxylation activation: After polishing, cleaning and drying the inner wall surface of the titanium alloy pipe body, plasma treatment is performed with working gas containing argon and water vapor to obtain a hydroxylated surface. S2, Aminated silane modification: The hydroxylated surface is immersed in an alcohol-water mixed solvent containing 3-aminopropyltriethoxysilane and reacted at 50-70°C for 0.5-2 hours to obtain an aminated surface; S3, Atom transfer radical polymerization initiator grafting: The aminated surface is placed in an organic solution containing an acyl halide initiator and an amidation reaction is carried out under low temperature conditions to introduce halogenated initiating groups onto the surface; S4. Construction of polymer brushes by surface-initiated atom transfer radical polymerization: The surface grafted with halogenated initiating groups is placed in a polymerization reaction vessel, water is used as the polymerization medium, acrylic acid monomers and crown ether functional monomers are added, and the reaction is carried out at 60-70°C for 24-48 hours under inert gas protection to form a copolymer brush layer of polyacrylic acid and crown ether functional monomers. The molar ratio of the acrylic acid monomer to the amino derivative monomer of benzo-18-crown-6 is 7:

3.

6. The marine antifouling system for titanium alloy pipelines according to claim 5, characterized in that, In step S1, the surface roughness after polishing is less than or equal to 200 nanometers; the cleaning is performed by ultrasonic cleaning with acetone, anhydrous ethanol and ultrapure water in sequence; the plasma treatment power is 150 to 250 watts and the treatment time is 2 to 4 minutes.

7. The marine antifouling system for titanium alloy pipelines according to claim 5, characterized in that, In step S2, the alcohol-water mixed solvent is a mixed solvent composed of anhydrous ethanol and ultrapure water in a volume ratio of 3:1 to 5:1; the amount of 3-aminopropyltriethoxysilane added is 0.5% to 2% of the total volume of the mixed solvent.

8. The marine antifouling system for titanium alloy pipelines according to claim 5, characterized in that, In step S3, the organic solution is a mixed solution of dichloromethane and triethylamine; the low temperature condition is an ice-water bath at 0–5 degrees Celsius; and the acyl halide initiator is 2-bromoisobutyryl bromide.

9. The marine antifouling system for titanium alloy pipelines according to claim 5, characterized in that, In S4, the crown ether functional monomer is an amino derivative of benzo-18-crown-6; The polymerization reaction is carried out in the presence of a catalytic system comprising cuprous bromide and 2,2'-bipyridine.

10. A method for constructing a marine antifouling system for titanium alloy pipelines according to any one of claims 1 to 9, characterized in that, Includes the following steps: Provide a titanium alloy pipe body and a copper alloy release source, and connect the copper alloy release source upstream of the titanium alloy pipe body; The inner wall of the titanium alloy pipe body is subjected to hydroxylation activation treatment; An amino-modified silane layer and an atom transfer radical polymerization initiator layer are sequentially grafted onto the inner wall after hydroxylation activation. Using acrylic acid monomers and crown ether functional monomers as comonomers, the smart polymer brush modification layer is formed on the inner wall of the titanium alloy pipe body by surface-initiated atom transfer radical polymerization.

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