An amphiphilic antifouling coating designed with pH charge response using L-histidine and its preparation

Abstract

The present invention belongs to the field of materials technology, specifically relating to amphiphilic antifouling coatings and methods for preparing the same. The present invention utilizes (3-mercaptopropyl)trimethoxysilane to cap and modify L-histidine methacrylamide and dimethylaminoethyl methacrylate, which are then cross-linked and cured with hydroxyl-terminated polydimethylsiloxane (PDMS) to form an amphiphilic polymer crosslinked network, avoiding macrophase separation of the amphiphilic polymers and achieving microphase separation. The invention also utilizes the expansion-contraction of hydrophilic and hydrophobic components in atmospheric and environmental environments to reconstruct the polymer surface, forming a surface micro-nanostructure. This, combined with pH-responsive surface charge changes, achieves efficient dynamic and static antifouling properties, providing new insights into the design of amphiphilic polymers.

Description

Technical Field

[0001] The invention belongs to the technical field of materials, and in particular relates to an amphiphilic antifouling coating and a preparation method thereof. Background Art

[0002] At present, ocean-going vessels and other offshore structures are all facing the problem of marine biofouling, which creates additional frictional resistance on the ships, reduces the sailing speed, leads to increased fuel consumption, and increases maintenance costs. Marine biofouling refers to the attachment of microorganisms, algae and macroscopic organisms to structures submerged in seawater and causes adverse accumulation. According to statistics, taking effective anti-fouling measures can effectively reduce the related problems caused by marine fouling. Among them, applying anti-fouling paint is the most economical and effective method among many anti-fouling methods. Therefore, vigorously developing marine anti-fouling paint technology and designing new anti-fouling paints are of far-reaching significance for ensuring the safety and reliability of deep-sea equipment in service, reducing the occurrence of major accidents, and extending the service life of deep-sea facilities.

[0003] Today, marine antifouling coatings are mainly divided into two categories: self-polishing coatings (SPCs) and fouling-release coatings (FRCs). Among them, SPCs use the slow and uniform hydrolysis of acrylate groups in the coating during the immersion process to form a stable polishing period, thereby obtaining a constant leaching rate of copper, zinc ions and antifouling agents. However, according to reports, the antifouling mechanism of antifouling agents such as copper ions has not yet been clarified, and there are many hidden dangers in the impact on the water environment and marine ecology. In response to this, many countries and regions are encouraging the development of new non-toxic antifouling coatings to avoid the damage to the environment caused by the large-scale accumulation of antifouling agents such as copper ions. FRCs coatings use silicone or fluorocarbon resins with low surface properties to reduce the adhesion strength between fouling organisms and the coating surface, and can be easily removed under seawater scouring or mechanical action. Compared with SPCs, FRCs are non-toxic and long-lasting, and have a significant anti-fouling effect on macroscopic fouling organisms such as barnacles. However, due to the hydrophobic nature of the surface, it is easy to undergo non-specific adsorption with proteins, bacteria, etc., which makes FRCs less effective in preventing bacteria and diatoms. A large amount of biofilm easily accumulates on the surface, which inactivates the surface properties and reduces the anti-fouling performance. Therefore, it is necessary to improve FRCs and enhance the overall anti-fouling performance of the coating. In addition, both SPCs and FRCs anti-fouling coatings need to rely on external water flow or manual flushing in a dynamic environment to achieve surface self-polishing or fouling release. On the contrary, the anti-fouling effect of the two coatings is significantly reduced in a static environment.

[0004] Faced with the complex marine environment, a single antifouling mechanism is unlikely to achieve broad-spectrum antifouling. In recent years, a large number of researchers have discovered that introducing hydrophilic components into FRCs to form amphiphilic polymers can effectively address the nonspecific adsorption of proteins, bacteria, and diatoms by FRCs. Amphiphilic coatings combine the fouling-release properties of the hydrophobic portion with the antifouling properties imparted by the dense hydration layer formed by the hydrophilic portion, effectively preventing fouling in marine environments. However, due to the thermodynamic incompatibility of the hydrophilic and hydrophobic components in the amphiphilic coating, significant phase separation occurs in the coating, destroying the basic mechanical properties of the coating and affecting the long-term antifouling ability of the coating. Moreover, after a small amount of fouling organisms attach to the surface, the microenvironment changes that occur, hindering or even inactivating the corresponding antifouling mechanism on the coating surface, necessitating the introduction of a corresponding response mechanism based on environmental changes to keep the coating surface in a dynamic state of change in order to cope with the complex and ever-changing marine fouling process. Currently, there are few reports on the preparation of intelligently responsive amphiphilic antifouling coatings. Summary of the Invention

[0005] In order to solve the problems existing in the prior art, the present invention first adopts a technical means to provide an amphiphilic antifouling coating designed with pH charge response using L-histidine, which has the following general formula:

[0006]

[0007] Among them, X:Y=100:1~5:1.

[0008] In order to solve the problems of the prior art, the present invention also provides a method for preparing the amphiphilic antifouling coating, comprising the following steps:

[0009] (1) Preparation of L-histidine methacrylamide:

[0010] First, L-histidine monomer, acryloyl chloride monomer, sodium nitrite, and potassium carbonate are mixed in proportion at 0°C under a nitrogen atmosphere; then, under a nitrogen atmosphere at room temperature, a nucleophilic substitution reaction occurs between the acyl chloride and the amino group to obtain L-histidine methacrylamide;

[0011] The molar ratio of the monomer L-histidine to the acryloyl chloride monomer is 1:1; the mass ratio of the total monomer, sodium nitrite and potassium carbonate is 4.7:0.1:1.8;

[0012] (2) Preparation of poly (dimethylaminoethyl methacrylate-co-L-histidine methacrylamide-co-(3-mercaptopropyl)trimethoxysilane) copolymer:

[0013] First, dimethylaminoethyl methacrylate monomer, L-histidine methacrylamide monomer, (3-mercaptopropyl)trimethoxysilane monomer, catalyst, and solvent are uniformly mixed; then, the temperature is raised to 85° C. under a nitrogen atmosphere, and free radical polymerization is carried out for more than 16 hours. The corresponding polymer is obtained after the reaction is completed;

[0014] The molar ratio of dimethylaminoethyl methacrylate monomer, L-histidine methacrylamide monomer, and (3-mercaptopropyl)trimethoxysilane monomer is 5:1:0.06 to 100:1:1.2; the mass ratio of the total monomers to the catalyst is 94.7:1 to 105.6:1.

[0015] (3) Preparation of organosilicon-based amphiphilic cross-linked polymer network:

[0016] First, poly (dimethylaminoethyl methacrylate-co-L-histidine methacrylamide-co-(3-mercaptopropyl)trimethoxysilane) copolymer, hydroxyl-terminated PDMS, and solution were uniformly mixed and stirred at room temperature for 30 minutes to obtain a mixed solution; then, methyltriacetoxysilane, catalyst, and solution were uniformly mixed, added to the mixed solution, and stirred at room temperature for 30 minutes to obtain a uniform transparent resin;

[0017] Among them, the mass ratio of poly (dimethylaminoethyl methacrylate-co-L-histidine methacrylamide-co-(3-mercaptopropyl)trimethoxysilane) copolymer, hydroxyl-terminated PDMS, methyltriacetoxysilane, and catalyst is 5:0.275:1:0.1 to 5:1.86:1:0.1.

[0018] Preferably, in step (2), the catalyst is at least one of azobisisobutyronitrile, azobisisoheptylnitrile and dicumyl peroxide.

[0019] Preferably, in step (2), the solvent is at least one of toluene, xylene, isobutanol, and tetrahydrofuran.

[0020] Preferably, in step (3), the catalyst is at least one of dibutyltin dilaurate, tin oxide, dioctyltin dilaurate, and tetraethyl titanate.

[0021] Preferably, in step (3), the solvent is at least one of toluene, xylene, isobutanol, tetrahydrofuran, xylene + isobutanol

[0022] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0023] (1) The present invention utilizes L-histidine methacrylamide and dimethylaminoethyl methacrylate to form a pH-responsive surface charge polymer, and utilizes the acidic metabolites produced after the attachment of the attached organisms to change the microenvironment of the coating surface, promote the change of the surface charge, realize the dynamic change of the coating surface, and improve the anti-fouling ability.

[0024] (2) The present invention uses (3-mercaptopropyl)trimethoxysilane to end-cap L-histidine methacrylamide and dimethylaminoethyl methacrylate, and cross-links and solidifies them with hydroxyl-terminated PDMS to form an amphiphilic polymer cross-linked network, avoiding the macroscopic phase separation of the amphiphilic polymer and achieving microphase separation; the expansion-contraction of the hydrophilic and hydrophobic components in the atmospheric environment and the environment is used to achieve polymer surface reconstruction and form surface micro-nanostructures, and the pH-responsive surface charge change is combined to achieve efficient dynamic and static antifouling, providing a new idea for the design of amphiphilic polymers. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the preparation process of the amphiphilic antifouling coating provided by the present invention: wherein a is a schematic diagram of the preparation of L-histidine methacrylamide (HisMAM) using L-histidine and acryloyl chloride; b is a schematic diagram of the preparation of poly(dimethylaminoethyl methacrylate-co-L-histidine methacrylamide-co-(3-mercaptopropyl)trimethoxysilane) copolymer using dimethylaminoethyl methacrylate (DMAEMA), L-histidine methacrylamide (HisMAM) and (3-mercaptopropyl)trimethoxysilane (MPTMS); c is a schematic diagram of the preparation of an organosilicon-based amphiphilic cross-linked polymer network using hydroxyl-terminated polydimethylsilane (HO-PDMS-OH), poly(dimethylaminoethyl methacrylate-co-L-histidine methacrylamide-co-(3-mercaptopropyl)trimethoxysilane) copolymer and methyltriacetoxysilane (METES);

[0026] Figure 2 Schematic diagram of the pH-responsive charge change mechanism of poly(dimethylaminoethyl methacrylate-co-L-histidine methacrylamide-co-(3-mercaptopropyl)trimethoxysilane) copolymer: a is a schematic diagram of the charge change of dimethylaminoethyl methacrylate (DMAEMA); b is a schematic diagram of the charge change of the zwitterion (L-histidine); c is a schematic diagram of the charge change of the (dimethylaminoethyl methacrylate-L-histidine methacrylamide) system;

[0027] Figure 3 Fourier transform infrared spectra of poly(dimethylaminoethyl methacrylate-co-L-histidine methacrylamide-co-(3-mercaptopropyl)trimethoxysilane) copolymer and poly(dimethylaminoethyl methacrylate-co-(3-mercaptopropyl)trimethoxysilane) copolymer;

[0028] Figure 4 Laser confocal microscopy surface morphology images of PDMS, PDHM-5, PDHM-10 and PDHM-15 samples before and after immersion;

[0029] Figure 5 This is a physical picture of the real sea hanging board test base in Example 1; among them, a is a picture of the real sea hanging board test base; b is a picture of the epoxy board dimensions;

[0030] Figure 6 These are the actual pictures of the four samples, PDMS, PDHM-5, PDHM-10 and PDHM-15, that were tested in the field for two months. DETAILED DESCRIPTION

[0031] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0032] Hexane, isobutanol, ethanol, xylene, azobisisobutyronitrile (AIBN), L-histidine, acryloyl chloride, dimethylaminoethyl methacrylate (DMAEMA), (3-mercaptopropyl)trimethoxysilane (MPTMS), and methyltriacetoxysilane (METES) used in the examples of the present invention were purchased from Aladdin Reagent (Shanghai) Co., Ltd. Ethyl acetate, sodium nitrite (NaNO2), potassium carbonate (K2CO3), and sodium hydroxide (NaOH) were purchased from Sigma-Aldrich (Shanghai) Trading Co., Ltd. Hydroxyl-terminated polydimethylsilane (HO-PDMS-OH) was purchased from Wacker Chemie AG.

[0033] Example 1 The present invention utilizes L-histidine to design a method for preparing a pH-charge-responsive amphiphilic antifouling coating, and the technical route is as follows: Figure 1 The specific steps are as follows:

[0034] 1. Preparation of L-histidine methacrylamide

[0035] Synthesis method: see Figure 1 Middle a.

[0036] 1) Dissolve 500 mg of weighed L-histidine and 20 mg of sodium nitrite (NaNO2) in 3.0 mL of 5% v / v potassium carbonate (K2CO3) aqueous solution. Stir the mixture in a 0°C ice-water bath and cool to 0°C. After thorough mixing, connect the sealing device and slowly add 400 μL of acryloyl chloride dropwise to the mixture under a nitrogen atmosphere at 0-5°C. After mixing thoroughly, stir the mixture at room temperature for 2 hours.

[0037] 2) After the reaction is complete, remove unreacted chemicals and byproducts using extraction. Remove the solvent by extracting with ethyl acetate. Adjust the pH of the solution to 5 with NaOH, and then extract the product with ethanol to remove excess L-histidine and NaCl.

[0038] 3) The extraction mixture was subjected to rotary evaporation to remove ethanol, the product was dissolved in ethanol again and precipitated in acetone, the precipitate was separated and dried under vacuum at 30° C. for 12 hours to obtain L-histidine methacrylamide (HisMAM).

[0039] 2. Preparation of Poly(dimethylaminoethyl methacrylate-co-L-histidine methacrylamide-co-(3-mercaptopropyl)trimethoxysilane) Copolymer

[0040] Synthesis method: see Figure 1 Middle b.

[0041] 1) Dissolve 0.22 g of L-histidine methacrylamide (HisMAM) in 5 mL of n-butanol. Add the n-butanol solution, 7.86 g of dimethylaminoethyl methacrylate (DMAEMA), 0.1 g of azobisisobutyronitrile (AIBN), and 10 mL of xylene to a round-bottom flask and stir well. Seal the flask and introduce nitrogen for 20 minutes to expel air to obtain a mixed solution.

[0042] 2) Dissolve 1.5 g of (3-mercaptopropyl)trimethoxysilane (MPTMS) in 5 mL of xylene in a constant pressure dropping funnel; place the round-bottom flask containing the mixed solution in an oil bath, heat the oil bath to 90°C, and maintain this temperature;

[0043] 3) Open the dropping funnel and slowly and uniformly add the mixed solution to the heated xylene over a period of about 1 hour to obtain a mixed solution. After the addition is complete, the mixture is incubated for 8 hours to obtain a product. The product is then repeatedly precipitated three times with an excess of n-hexane and vacuum-dried at 60°C for at least 24 hours to obtain a poly(dimethylaminoethyl methacrylate-co-L-histidine methacrylamide-co-(3-mercaptopropyl)trimethoxysilane) copolymer resin.

[0044] 3. Preparation of silicone-based amphiphilic cross-linked polymer networks

[0045] Synthesis method: see Figure 1 Middle c.

[0046] 1) Dissolve 5 g of hydroxyl-terminated polydimethylsilane (HO-PDMS-OH) and 1.64 g of poly(dimethylaminoethyl methacrylate-co-L-histidine methacrylamide-co-(3-mercaptopropyl)trimethoxysilane) copolymer in 11 mL of a xylene-isobutanol mixed solution (10 mL of xylene and 1 mL of isobutanol) and stir thoroughly for 30 minutes to obtain a uniform mixed solution;

[0047] 2) 1 g of methyltriacetoxysilane (METES) and 0.1 g of dibutyltin dilaurate (DBTDL) were added to the mixed solution and stirred for 30 minutes to obtain a transparent resin with a certain viscosity. The resin was brush-coated on an epoxy resin plate and self-cured in a ventilated environment at room temperature for 24 hours to obtain an L-histidine-designed pH-charge-responsive amphiphilic antifouling coating, designated PDHM-X, where X is the mass fraction of poly(dimethylaminoethyl methacrylate-co-L-histidine methacrylamide-co-(3-mercaptopropyl)trimethoxysilane) copolymer relative to the total mass of PDMS + METES, expressed in wt%.

[0048] In order to solve the phase separation problem between hydrophilic and hydrophobic components in amphiphilic coatings, the present invention uses a silane coupling agent to modify the hydrophilic component, and undergoes a dealcoholization condensation reaction with the hydroxyl-terminated PDMS to form an amphiphilic cross-linked polymer network, thereby avoiding macroscopic phase separation between the components, achieving microphase separation through the cross-linked network, and enhancing the basic mechanical properties of the coating. At the same time, the hydrophilic and hydrophobic components of the resin itself will respond to the environment in the seawater environment, undergo surface reconstruction to form a micro-nano structure, and enhance the antifouling activity; then, by introducing L-histidine zwitterions, the coating is given a pH response mechanism. When fouling organisms attach, acidic metabolites are produced that affect the pH of the microenvironment on the coating surface, causing the surface charge to be converted to the same as the surface charge of the microorganism, resulting in charge repulsion and preventing further attachment of the microorganism. The pH response charge change mechanism of the poly (dimethylaminoethyl methacrylate-co-L-histidine methacrylamide-co-(3-mercaptopropyl)trimethoxysilane) copolymer prepared by the present invention is as follows: Figure 2 At the same time, L-histidine as a natural amino acid ensures that the coating is natural, non-toxic, and environmentally friendly.

[0049] 4. Fourier Transform Infrared Spectroscopy Characterization

[0050] The poly(dimethylaminoethyl methacrylate-co-L-histidine methacrylamide-co-(3-mercaptopropyl)trimethoxysilane) copolymer synthesized in this example was characterized by Fourier transform infrared spectroscopy (Nicolet iS50, Thermofisher, USA). Poly(dimethylaminoethyl methacrylate-co-L-histidine methacrylamide-co-(3-mercaptopropyl)trimethoxysilane) copolymer (p(DMAEMA-HisMAM-MPTMS, red line, Figure 3 ) and poly(dimethylaminoethyl methacrylate-co-(3-mercaptopropyl)trimethoxysilane) copolymer (p(DMAEMA-MPTMS), blue line, Figure 3 ), Si-O bonds (1039cm -1 ), CN bond (1273cm -1 ), and C=O bond (1727 cm -1 In addition, the characteristic absorption band of amide-II can be observed at 1516 cm in the infrared spectrum of poly(dimethylaminoethyl methacrylate-co-L-histidine methacrylamide-co-(3-mercaptopropyl)trimethoxysilane) copolymer. -1 , which proves that L-histidine methacrylamide was successfully polymerized to form poly(dimethylaminoethyl methacrylate-co-L-histidine methacrylamide-co-(3-mercaptopropyl)trimethoxysilane) copolymer.

[0051] 5. Confocal Laser Surface Characterization

[0052] The surface morphology of the amphiphilic cross-linked polymer network synthesized in this example was compared before and after resin coating immersion using a laser confocal microscope (KEYENCE VK-X250, Japan KEYENCE Company). Figure 4 ). First, the three samples of PDHM-5, PDHM-10 and PDHM-15 were photographed by laser confocal microscopy to capture the 3D morphology and physical images of the sample surface. PDHM-X showed obvious microphase separation, the hydrophobic PDMS area was relatively smooth, and the hydrophilic polymer aggregated to form a round bubble; then the three samples of PDHM-5, PDHM-10 and PDHM-15 were immersed in deionized water for 3 days, and the surface morphology changes were observed again by laser confocal microscopy. The PDHM-X coatings all underwent surface reconstruction, from a round bubble structure to a micro-nano mountain-shaped structure. As the amount of poly (dimethylaminoethyl methacrylate-co-L-histidine methacrylamide-co-(3-mercaptopropyl)trimethoxysilane) copolymer added increased, the surface micro-nano structure became more dense.

[0053] 6. Real sea hanging board

[0054] The hanging board experiment was carried out on a floating raft at Dalipu Island, Xiamen (24°33'N, 118°09'E) under actual marine environment. Figure 5 In middle a, there are many types of fouling organisms in the test area.

[0055] The amphiphilic antifouling coating was prepared by mixing PDMS and poly (dimethylaminoethyl methacrylate-co-L-histidine methacrylamide-co-(3-mercaptopropyl)trimethoxysilane) copolymer in different mass ratios (WL-histidine accounts for 5wt%, 10wt%, and 15wt% of the total mass of PDMS+METES, respectively). Three experimental groups were formed, namely PDHM-5, PDHM-10, and PDHM-15. The coated plate was based on an epoxy plate (100mm×80mm×3mm) (e.g. Figure 5 As shown in b), an amphiphilic antifouling coating is applied to the surface of the substrate by a brush coating method to form a coating on the surface of the epoxy board substrate, and then the solvent on the coating surface is volatilized in a natural state, and then vacuum dried for 24 hours to obtain the coating.

[0056] The PDMS resin coated plate is based on an epoxy plate (100 mm × 80 mm × 3 mm) (e.g. Figure 5 As shown in b), PDMS resin is coated on the surface of the substrate using a brush coating method to form a coating on the surface of the epoxy board substrate, and then the solvent on the surface of the coating is volatilized in a natural state, and then vacuum dried for 24 hours to obtain.

[0057] The coating thickness of the plates coated with amphiphilic antifouling paint and PDMS resin is 100-200μm. The surface comparison of the four sample plates after hanging for 2 months in the actual marine environment is as follows Figure 6 : A large number of barnacles are attached to the surface of PDMS resin, and at the same time, attachment traces formed by the reversible attachment of some barnacles can be observed. In addition, a silt layer formed by sea mud and algae can be observed on the surface; compared with PDMS resin, the surface of PDHM-5 coating has less barnacles attached, but a large amount of silt layer is present on the surface; the surfaces of PDHM-10 and PDHM-15 coatings are relatively smooth, without barnacles attached, and no silt layer exists. This proves that after 2 months of exposure to actual marine environment, the antifouling properties of PDHM-10 and PDHM-15 coatings are significantly better than those of PDMS resin and PDHM-5 coatings, indicating that the pH charge-responsive amphiphilic antifouling coating designed using L-histidine provided by the present invention has good antifouling properties.

[0058] Example 2 The present invention utilizes L-histidine to design a method for preparing a pH-charge-responsive amphiphilic antifouling coating, and the technical route is as follows: Figure 1 The specific steps are as follows:

[0059] 1. Preparation of L-histidine methacrylamide

[0060] Synthesis method: see Figure 1 Middle a.

[0061] 1) Dissolve 500 mg of weighed L-histidine and 20 mg of sodium nitrite (NaNO2) in 3.0 mL of 5% v / v potassium nitrate (K2CO3) aqueous solution. Stir the mixture in a 0°C ice-water bath and cool to 0°C. After thorough mixing, connect the sealing device and slowly add 400 μL of acryloyl chloride dropwise to the mixture under a nitrogen atmosphere at 0-5°C. After mixing thoroughly, stir the mixture at room temperature for 2 hours.

[0062] 2) After the reaction is complete, remove unreacted chemicals and byproducts using extraction. Remove the solvent by extracting with ethyl acetate. Adjust the pH of the solution to 5 with NaOH, and then extract the product with ethanol to remove excess L-histidine and NaCl.

[0063] 3) The extraction mixture was subjected to rotary evaporation to remove ethanol, the product was dissolved in ethanol again and precipitated in acetone, the precipitate was separated and dried under vacuum at 30° C. for 12 hours to obtain L-histidine methacrylamide (HisMAM).

[0064] 2. Preparation of Poly(dimethylaminoethyl methacrylate-co-L-histidine methacrylamide-co-(3-mercaptopropyl)trimethoxysilane) Copolymer

[0065] Synthesis method: see Figure 1 Middle b.

[0066] 1) Dissolve 2.2 g of L-histidine methacrylamide (HisMAM) in 5 mL of n-butanol. Add the n-butanol solution, 15.72 g of dimethylaminoethyl methacrylate (DMAEMA), 0.2 g of azobisisobutyronitrile (AIBN), and 10 mL of xylene to a round-bottom flask and stir thoroughly. Seal the flask and introduce nitrogen for 20 minutes to expel air to obtain a mixed solution.

[0067] 2) Dissolve 3 g of (3-mercaptopropyl)trimethoxysilane (MPTMS) in 5 mL of xylene in a constant pressure dropping funnel; place the round-bottom flask containing the mixed solution in an oil bath, heat the oil bath to 90°C, and maintain this temperature;

[0068] 3) Open the dropping funnel and slowly and uniformly add the mixed solution to the heated xylene over a period of about 1 hour to obtain a mixed solution. After the addition is complete, the mixture is incubated for 8 hours to obtain a product. The product is then repeatedly precipitated three times with an excess of n-hexane and vacuum-dried at 60°C for at least 24 hours to obtain a poly(dimethylaminoethyl methacrylate-co-L-histidine methacrylamide-co-(3-mercaptopropyl)trimethoxysilane) copolymer resin.

[0069] 3. Preparation of silicone-based amphiphilic cross-linked polymer networks

[0070] Synthesis method: see Figure 1 Middle c.

[0071] 1) Dissolve 5 g of hydroxyl-terminated polydimethylsilane (HO-PDMS-OH) and 1.64 g of poly(dimethylaminoethyl methacrylate-co-L-histidine methacrylamide-co-(3-mercaptopropyl)trimethoxysilane) copolymer in 11 mL of a xylene-isobutanol mixed solution (10 mL of xylene and 1 mL of isobutanol) and stir thoroughly for 30 minutes to obtain a uniform mixed solution;

[0072] 2) 1 g of methyltriacetoxysilane (METES) and 0.1 g of dibutyltin dilaurate (DBTDL) were added to the mixed solution and stirred for 30 minutes to obtain a transparent resin with a certain viscosity. The resin was brush-coated on an epoxy resin plate and self-cured in a ventilated environment at room temperature for 24 hours to obtain an L-histidine-designed pH-charge-responsive amphiphilic antifouling coating, designated PDHM-X, where X is the mass fraction of poly(dimethylaminoethyl methacrylate-co-L-histidine methacrylamide-co-(3-mercaptopropyl)trimethoxysilane) copolymer relative to the total mass of PDMS + METES, expressed in wt%.

[0073] Example 3 The present invention uses L-histidine to design a method for preparing a pH-charge-responsive amphiphilic antifouling coating. The technical route is as follows: Figure 1 The specific steps are as follows:

[0074] 1. Preparation of L-histidine methacrylamide

[0075] Synthesis method: see Figure 1 Middle a.

[0076] 1) Dissolve 500 mg of weighed L-histidine and 20 mg of sodium nitrite (NaNO2) in 3.0 mL of 5% v / v potassium nitrate (K2CO3) aqueous solution. Stir the mixture in a 0°C ice-water bath and cool to 0°C. After thorough mixing, connect the sealing device and slowly add 400 μL of acryloyl chloride dropwise to the mixture under a nitrogen atmosphere at 0-5°C. After mixing thoroughly, stir the mixture at room temperature for 2 hours.

[0077] 2) After the reaction is complete, remove unreacted chemicals and byproducts using extraction. Remove the solvent by extracting with ethyl acetate. Adjust the pH of the solution to 5 with NaOH, and then extract the product with ethanol to remove excess L-histidine and NaCl.

[0078] 3) The extraction mixture was subjected to rotary evaporation to remove ethanol, the product was dissolved in ethanol again and precipitated in acetone, the precipitate was separated and dried under vacuum at 30° C. for 12 hours to obtain L-histidine methacrylamide (HisMAM).

[0079] 2. Preparation of Poly(dimethylaminoethyl methacrylate-co-L-histidine methacrylamide-co-(3-mercaptopropyl)trimethoxysilane) Copolymer

[0080] Synthesis method: see Figure 1 Middle b.

[0081] 1) Dissolve 0.55 g of L-histidine methacrylamide (HisMAM) in 5 mL of n-butanol. Add the n-butanol solution, 3.93 g of dimethylaminoethyl methacrylate (DMAEMA), 0.05 g of azobisisobutyronitrile (AIBN), and 10 mL of xylene to a round-bottom flask and stir well. Seal the flask and introduce nitrogen for 20 minutes to expel air to obtain a mixed solution.

[0082] 2) Dissolve 0.75 g of (3-mercaptopropyl)trimethoxysilane (MPTMS) in 5 mL of xylene in a constant pressure dropping funnel; place the round-bottom flask containing the mixed solution in an oil bath, heat the oil bath to 90°C, and maintain this temperature;

[0083] 3) Open the dropping funnel and slowly and uniformly add the mixed solution to the heated xylene over a period of about 1 hour to obtain a mixed solution. After the addition is complete, the mixture is incubated for 8 hours to obtain a product. The product is then repeatedly precipitated three times with an excess of n-hexane and vacuum-dried at 60°C for at least 24 hours to obtain a poly(dimethylaminoethyl methacrylate-co-L-histidine methacrylamide-co-(3-mercaptopropyl)trimethoxysilane) copolymer resin.

[0084] 3. Preparation of silicone-based amphiphilic cross-linked polymer networks

[0085] Synthesis method: see Figure 1 Middle c.

[0086] 1) Dissolve 5 g of hydroxyl-terminated polydimethylsilane (HO-PDMS-OH) and 1.64 g of poly(dimethylaminoethyl methacrylate-co-L-histidine methacrylamide-co-(3-mercaptopropyl)trimethoxysilane) copolymer in 11 mL of a xylene-isobutanol mixed solution (10 mL of xylene and 1 mL of isobutanol) and stir thoroughly for 30 minutes to obtain a uniform mixed solution;

[0087] 2) 1 g of methyltriacetoxysilane (METES) and 0.1 g of dibutyltin dilaurate (DBTDL) were added to the mixed solution and stirred for 30 minutes to obtain a transparent resin with a certain viscosity. The resin was brush-coated on an epoxy resin plate and self-cured in a ventilated environment at room temperature for 24 hours to obtain an L-histidine-designed pH-charge-responsive amphiphilic antifouling coating, designated PDHM-X, where X is the mass fraction of poly(dimethylaminoethyl methacrylate-co-L-histidine methacrylamide-co-(3-mercaptopropyl)trimethoxysilane) copolymer relative to the total mass of PDMS + METES, expressed in wt%.

Claims

1. An amphiphilic antifouling coating designed with pH charge response using L-histidine, characterized in that: Has the following general formula: ； Among them, X:Y=100:1~5:

1.

2. A method for preparing an amphiphilic antifouling coating according to claim 1, characterized in that: The steps include: (1) Preparation of L-histidine methacrylamide: First, L-histidine monomer, acryloyl chloride monomer, sodium nitrite, and potassium carbonate are mixed in proportion at 0°C under a nitrogen atmosphere; then, L-histidine methacrylamide is obtained by reacting at room temperature under a nitrogen atmosphere; The molar ratio of L-histidine monomer to acryloyl chloride monomer is 1:1; the mass ratio of total monomers, sodium nitrite and potassium carbonate is 4.7:0.1:1.8; (2) Preparation of poly (dimethylaminoethyl methacrylate-co-L-histidine methacrylamide-co-(3-mercaptopropyl)trimethoxysilane) copolymer: First, dimethylaminoethyl methacrylate monomer, L-histidine methacrylamide monomer, (3-mercaptopropyl)trimethoxysilane monomer, catalyst, and solvent are uniformly mixed; then, the temperature is raised to 85° C. under a nitrogen atmosphere, and free radical polymerization is carried out for more than 16 hours. The corresponding copolymer is obtained after the reaction is completed; The molar ratio of dimethylaminoethyl methacrylate monomer, L-histidine methacrylamide monomer, and (3-mercaptopropyl)trimethoxysilane monomer is 5:1:0.06 to 100:1:1.2; the mass ratio of the total monomers to the catalyst is 94.7:1 to 105.6:

1. (3) Preparation of silicone-based amphiphilic cross-linked polymer networks: First, poly(dimethylaminoethyl methacrylate-co-L-histidine methacrylamide-co-(3-mercaptopropyl)trimethoxysilane) copolymer, hydroxyl-terminated PDMS, and solvent were uniformly mixed and stirred at room temperature for 30 minutes to obtain a mixed solution. Then, methyltriacetoxysilane, catalyst, and solvent were uniformly mixed, added to the mixed solution, and stirred at room temperature for 30 minutes to obtain a uniform transparent resin. Among them, the mass ratio of poly (dimethylaminoethyl methacrylate-co-L-histidine methacrylamide-co-(3-mercaptopropyl)trimethoxysilane) copolymer, hydroxyl-terminated PDMS, methyltriacetoxysilane, and catalyst is 5:0.275:1:0.1 to 5:1.86:1:0.

1.

3. The method for preparing an amphiphilic antifouling coating according to claim 2, wherein: In the step (2), the catalyst is at least one of azobisisobutyronitrile, azobisisoheptanenitrile, and dicumyl peroxide.

4. The method for preparing an amphiphilic antifouling coating according to claim 2, wherein: In the step (2), the solvent is at least one of toluene, xylene, isobutanol, and tetrahydrofuran.

5. The method for preparing the amphiphilic antifouling coating according to claim 2, wherein: In the step (3), the catalyst is at least one of dibutyltin dilaurate, tin oxide, dioctyltin dilaurate, and tetraethyl titanate.

6. The method for preparing an amphiphilic antifouling coating according to claim 2, wherein: In the step (3), the solvent is at least one of toluene, xylene, isobutanol, and tetrahydrofuran.

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