Berberine-modified carbon nanotube / polydimethylsiloxane antifouling composite coating as well as preparation method and application thereof

Abstract

The invention discloses a berberine modified carbon nano tube / polydimethylsiloxane antifouling composite coating as well as a preparation method and application thereof. The composite coating is prepared from 85 to 90 percent of polydimethylsiloxane PDMS, 8 to 12 percent of carbon nano tube and 1.5 to 2.5 percent of berberine BE. A hydrogen bond is formed by carboxyl of cMWCNTs and hydroxyl of berberine, so that the stability of the antifouling agent is improved; by adopting an ultrasonic dispersion-step mixing preparation process, the problems of cMWCNTs agglomeration and non-uniform berberine dispersion are effectively solved; the formation of a microbial film at the early stage of fouling is effectively inhibited by regulating and controlling a microbial community structure; by regulating and controlling the microbial community structure in the early stage of fouling, colonization of fouling microorganisms is inhibited, and the ecological anti-fouling effect is achieved. The prepared composite coating has the advantages of being environmentally friendly, lasting in antifouling efficiency, excellent in mechanical performance and the like, and can be widely applied to fouling, corrosion and protection of ships, ocean engineering equipment and the like.

Description

Technical Field

[0001] This invention relates to a marine antifouling material, specifically to a berberine-modified carbon nanotube / polydimethylsiloxane antifouling composite coating, its preparation method, and its application. Background Technology

[0002] Marine biofouling refers to the phenomenon where marine microorganisms, algae, and large organisms attach and grow on the surfaces of ships and marine engineering equipment, leading to decreased equipment performance, increased energy consumption, and accelerated corrosion, causing hundreds of billions of dollars in economic losses globally each year. Traditional antifouling materials mostly rely on biocides containing heavy metals (such as tributyltin), which, while able to inhibit fouling in the short term, cause serious pollution to the marine ecosystem and have been banned by the International Maritime Organization. Existing environmentally friendly antifouling materials include self-polishing coatings and biomimetic coatings, but they suffer from short-term antifouling effects and insufficient specificity in inhibiting microorganisms. Polydimethylsiloxane (PDMS) has become a research hotspot for fouling desorption materials due to its low surface energy and hydrophobicity, but its mechanical properties are poor and its effect on inhibiting early microbial film formation is limited. Carboxylated carbon nanotubes (cMWCNTs) can improve the mechanical properties of PDMS as reinforcing fillers, but their antifouling efficacy when used alone still needs improvement. Natural antifouling agents (such as berberine) have the advantages of being environmentally friendly and low in toxicity, but the synergistic antifouling mechanism of their combination with cMWCNTs / PDMS has not yet been reported. Summary of the Invention

[0003] To address the shortcomings of existing antifouling materials, such as insufficient environmental friendliness, poor mechanical properties, difficulty in balancing antifouling efficacy with environmental friendliness, and limited effectiveness in inhibiting early microbial biofilm formation, this invention provides a berberine-modified carbon nanotube / polydimethylsiloxane antifouling composite coating, its preparation method, and its application. This invention improves the stability of the antifouling agent by forming hydrogen bonds between the carboxyl groups of cMWCNTs and the hydroxyl groups of berberine; it effectively solves the problems of cMWCNT aggregation and uneven berberine dispersion by employing an "ultrasonic dispersion-stepwise mixing" preparation process; it effectively inhibits the formation of early-stage microbial biofilms by regulating the microbial community structure; and it achieves an eco-friendly antifouling effect by inhibiting the colonization of fouling microorganisms through the regulation of the early-stage microbial community structure.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] A berberine-modified carbon nanotube / polydimethylsiloxane antifouling composite coating, by weight percentage, is composed of the following components: polydimethylsiloxane (PDMS) 85-90%, carbon nanotubes 8-12%, and berberine (BE) 1.5-2.5%, wherein:

[0006] The PDMS, as the matrix, provides low surface energy; carbon nanotubes, as the reinforcing phase, enhance mechanical properties; berberine, as an antifouling agent, specifically inhibits dominant fouling microorganisms (such as Proteobacteria and diatoms); carbon nanotubes improve coating strength through physical filling, while berberine inhibits early film formation by altering the relative abundance of the microbial community, especially showing a significant inhibitory effect on the colonization of Gamma-Proteobacteria and Diatoms. The selection and function of each component are optimized based on marine antifouling requirements and material properties.

[0007] The PDMS has a viscosity of 5000~8000 cSt (such as Dow Corning Sylgard 184), and the mass ratio of PDMS matrix (Part A) to curing agent (Part B) is 10:1, providing a substrate with low surface energy (surface energy ≤20 mN / m) and high hydrophobicity (water contact angle ≥105°), which can reduce the initial attachment of marine microorganisms. The low surface energy characteristics of PDMS make it difficult for microorganisms to colonize in the early stage of fouling, while providing a dispersion carrier for CNTs and berberine.

[0008] The types of carbon nanotubes mentioned are not limited to carboxyl-modified multi-walled carbon nanotubes (cMWCNTs); carboxyl-modified single-walled carbon nanotubes (cSWCNTs) and other types can also achieve similar effects.

[0009] The cMWCNTs have a length of 10–30 μm, a diameter of 20–50 nm, and a carboxyl content of [missing information]. At 2.0 wt%, cMWCNTs, uniformly embedded in a PDMS matrix through ultrasonic dispersion, can improve the coating tensile strength to 3.0~3.5 MPa (compared to 1.5~2.0 MPa for pure PDMS), enhance its abrasion resistance under seawater erosion, and inhibit film formation by altering microbial attachment sites through nanoscale roughness. When the cMWCNTs have a length of 20~30 μm and a diameter of 40~50 nm, the ultrasonic power is 500 W and the dispersion time is 60 min; when the cMWCNTs have a length of 10~20 μm and a diameter of 20~30 nm, the ultrasonic power is 300 W and the dispersion time is 50 min.

[0010] The purity of the berberine Berberine has an antifouling effect in concentrations ranging from 1.5% to 2.5%, with 2.0% being the optimal value. After being dissolved in ethanol, it is dispersed in the composite system. Berberine can selectively inhibit the permeability of microbial cell membranes, significantly reduce the relative abundance of Proteobacteria (especially Gamma-Proteobacteria) and Diatoms, reduce the colonization of dominant fouling species (such as Cyclobacterium and Navicula) in microbial biofilms, and reduce the diversity of microbial biofilm communities.

[0011] A method for preparing the above-mentioned berberine-modified carbon nanotube / polydimethylsiloxane antifouling composite coating includes the following steps:

[0012] Step 1: Add carbon nanotubes to anhydrous ethanol and ultrasonically disperse them at a power of 300~500 W for 45~60 min to obtain a carbon nanotube dispersion with a concentration of 2~10 mg / mL.

[0013] Step 2: Mix the PDMS matrix and curing agent at a mass ratio of 10:1, add the carbon nanotube dispersion obtained in Step 1, and mechanically stir at 300~400 r / min for 1.5~2 h, followed by vacuum stirring. -0.09 MPa yielded a carbon nanotube / PDMS premix;

[0014] Step 3: Add berberine to the premixed solution obtained in Step 2, and continue stirring for 30-60 minutes to ensure that the berberine is evenly dispersed, thus obtaining the BECP mixture;

[0015] Step 4: Apply the BECP mixture obtained in Step 3 to the pretreated substrate surface and cure it at 90~100℃ for 5~6 h with a heating rate of 3~5℃ / min to obtain an antifouling composite coating. The substrate pretreatment method is as follows: sanding with 800-grit and 1200-grit sandpaper in sequence, ultrasonic cleaning with anhydrous ethanol for 10~20 min, and drying with nitrogen. The substrate is carbon steel, glass, polyethylene, 316L stainless steel, or glass fiber reinforced composite material, and the coating method is dip coating (lifting speed 40~50 mm / min) or spray coating (nozzle diameter 0.5~0.6 mm, air pressure 0.3~0.4 MPa). The wet film thickness is 80~100 μm, and the dry film thickness is 45~60 μm.

[0016] The stirring speed, curing temperature and other parameters in the preparation process of this invention can be adjusted according to actual needs, as long as the components can be uniformly dispersed and fully cured.

[0017] The application of the above-mentioned berberine-modified carbon nanotube / polydimethylsiloxane antifouling composite coating in the field of marine antifouling is specifically applicable to the surface antifouling treatment of ship hulls, offshore platform legs, or marine aquaculture cages. It can inhibit the formation of early-stage microbial biofilm communities and has a long antifouling effect. 6 months; the inhibition rate against early-stage marine fouling prokaryotic microorganisms (Proteobacteria, Bacteroidetes) and eukaryotic microorganisms (Diatoms, Annelida) was [missing information]. 60%.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. This invention achieves a synergistic effect of "mechanical enhancement - microbial biofilm community regulation - environmentally friendly ecofouling" through component optimization and process control. The low surface energy of PDMS makes it difficult for microorganisms to form stable attachments, and the nanoscale rough structure of cMWCNTs further increases the resistance to microbial colonization. The combination of these two factors reduces the initial attachment amount by 30-40%. Berberine, through slow diffusion and release, interferes with the quorum sensing system of microorganisms, hindering biofilm signal transmission; it achieves an inhibition rate of over 60% against γ-Proteobacteria (the main pioneer fouling microorganisms), reducing their inducing effect on large fouling organisms (such as barnacle larvae).

[0020] 2. This invention introduces berberine at a specific concentration after combining cMWCNTs with PDMS, which can significantly regulate the structure of natural microbial biofilm communities in the early stage of marine biofouling, reduce the diversity and abundance of prokaryotic and eukaryotic microorganisms closely related to marine biofouling, and has a targeted inhibitory effect on dominant biofouling microorganisms such as Proteobacteria and Diatoms.

[0021] 3. This invention reduces the mucus layer formation by altering the composition of the microbial community, decreasing the Proteobacteria / Cyanobacteria ratio (from 9.6 in pure PDMS to 4.2) and the relative abundance of diatoms among eukaryotic microorganisms (from 27.1% to 17.5%), thereby effectively inhibiting or hindering the attachment of subsequent large fouling organisms.

[0022] 4. The composite coating prepared by this invention has the characteristics of being environmentally friendly, having long-lasting antifouling performance, and having excellent mechanical properties. It can be widely used for the protection against fouling, corrosion, and other damage to ships and marine engineering equipment. Attached Figure Description

[0023] Figure 1 The actual marine antifouling effect of CP and BECP composite coatings in a marine environment (6 months);

[0024] Figure 2 The relative abundance of prokaryotic microbial communities in the early stage of microbial film formation on the surface of BECP and CP composite coatings at the phylum level;

[0025] Figure 3 Comparison of the relative abundance of prokaryotic microbial communities in the early stage of microbial fouling on the surfaces of BECP and CP composite coatings at the tertiary level;

[0026] Figure 4 Comparison of Chao 1 index, observed species, and Faith PD index of prokaryotic microbial communities in the early stage of microbial fouling on BECP and CP composite coating surfaces;

[0027] Figure 5Comparison of Shannon index, Simpson index, and Evenness index for early-stage microbial biofilm formation on BECP and CP composite coating surfaces;

[0028] Figure 6 Comparison of the relative abundance of eukaryotic microbial communities in the early stage of microbial biofilm formation on the surface of BECP and CP composite coatings at the phylum level;

[0029] Figure 7 Comparison of Chao 1 index, observed scies, and Faith PD index for early-stage microbial biofilm formation on BECP and CP composite coating surfaces;

[0030] Figure 8 A comparison of Shannon index, Simpson index, and Evenness index for early microbial biofilm formation on BECP and CP composite coating surfaces. Detailed Implementation

[0031] The technical solution of the present invention will be further described below with reference to the accompanying drawings, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention that do not depart from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0032] Example 1: Preparation of berberine-modified cMWCNTs / PDMS composite coating

[0033] (1) Preparation of cMWCNTs dispersion: Weigh 1 g of cMWCNTs and add it to 200 mL of anhydrous ethanol. Disperse the dispersion by ultrasonication at 400 W for 45 min (ultrasonic probe diameter 10 mm, amplitude 50%) to obtain a dispersion with a concentration of 5 mg / mL. Ensure that the CNTs do not agglomerate (the particle size distribution range is detected by dynamic light scattering instrument). 1.2).

[0034] (2) Preparation of CNTs / PDMS premix: Take 100 g of PDMS (viscosity 8000 cSt) and 10 g of curing agent and mix them in a glass beaker. Stir magnetically at 400 r / min for 5 min until homogeneous. Add 50 mL of the above CNTs dispersion and stir at 400 r / min for 1.5 h. During this period, pick up the mixture with a glass rod every 30 min to observe until the mixture is homogeneous and viscous (without obvious particles). Place the mixture in a vacuum drying oven and dry it under vacuum. Degassing was performed at -0.09 MPa for 30 min to remove air bubbles (ensuring the coating is pore-free after curing), yielding the cMWCNTs / PDMS premix.

[0035] (3) Preparation of BECP mixture: Add 2.2 g of berberine powder (pre-dissolved in 22 mL of anhydrous ethanol, concentration of 0.1 g / mL) to the premixed solution, stir at 300 r / min for 45 min until uniform, and observe with a fluorescence microscope (excitation wavelength 450 nm) to ensure that the berberine is uniformly dispersed (without local aggregation).

[0036] (4) Substrate pretreatment: Carbon steel or glass substrates are successively polished with 800-grit and 1200-grit sandpaper until the surface roughness Ra=0.8~1.6 μm, ultrasonically cleaned with anhydrous ethanol for 15 min (power 200 W), and dried with nitrogen.

[0037] (5) Coating formation: The mixture is coated on a 10 cm × 10 cm carbon steel surface by dip coating (lifting speed 50 mm / min) or spray coating (nozzle diameter 0.5 mm, air pressure 0.3 MPa), and cured in an oven at 90℃ for 5 h (heating rate 5℃ / min) to obtain a composite coating with a thickness of about 50 μm. After cooling to room temperature, it is ready for use.

[0038] Example 2:

[0039] (1) Preparation of cMWCNTs dispersion: Weigh 1.2 g of cMWCNTs (length 20~30 μm, diameter 40~50 nm), add to 150 mL of anhydrous ethanol, and ultrasonically disperse at 500 W for 60 min (ultrasonic probe diameter 10 mm, amplitude 50%) to obtain a dispersion with a concentration of 8 mg / mL. The particle size distribution range was detected by dynamic light scattering instrument. Version 1.0 ensures that CNTs are fully dispersed.

[0040] (2) Preparation of CNTs / PDMS premix: Take 90 g of PDMS (viscosity 6000 cSt) and 9 g of curing agent and mix them in a glass beaker. Stir magnetically at 350 r / min for 8 min until homogeneous. Slowly add 60 mL of the above CNTs dispersion and stir at 350 r / min for 2 h. During this period, pick up the mixture with a glass rod every 30 min to observe and ensure that there are no obvious particles in the mixture. Place the mixture in a vacuum drying oven and dry it under vacuum. Degassing was performed at -0.09 MPa for 35 min to obtain cMWCNTs / PDMS premix.

[0041] (3) Preparation of BECP mixture: Add 2.0 g of berberine (pre-dissolved in 20 mL of anhydrous ethanol, concentration of 0.1 g / mL) to the premixed solution, stir at 350 r / min for 60 min, and observe with a fluorescence microscope (excitation wavelength 450 nm) to ensure that the berberine is uniformly dispersed (without local aggregation).

[0042] (4) Substrate pretreatment: 316L stainless steel substrate is used. The substrate is polished with 1000 grit and 1500 grit sandpaper until the surface roughness Ra=0.5~1.0 μm. Acetone ultrasonic cleaning for 10 min, anhydrous ethanol ultrasonic cleaning for 15 min (power 250 W), and nitrogen blowing dry.

[0043] (5) Coating formation: The mixture was coated onto the pretreated stainless steel surface by spraying (nozzle diameter 0.6 mm, air pressure 0.4 MPa). The wet film thickness was controlled to be 100 μm. The mixture was cured in an oven at 100℃ for 6 h (heating rate of 3℃ / min) to obtain a composite coating with a thickness of about 60 μm. The coating was then cooled to room temperature for later use.

[0044] Example 3:

[0045] (1) Preparation of cMWCNTs dispersion: Weigh 0.8 g of cMWCNTs (length 10~20 μm, diameter 20~30 nm), add to 200 mL of anhydrous ethanol, and ultrasonically disperse at 300 W for 50 min (ultrasonic probe diameter 10 mm, amplitude 50%) to obtain a dispersion with a concentration of 4 mg / mL. The particle size distribution range was detected by dynamic light scattering instrument. 1.1.

[0046] (2) Preparation of CNTs / PDMS premix: 95 g of PDMS (viscosity 5000 cSt) and 9.5 g of curing agent were mixed in a glass beaker and magnetically stirred at 300 r / min for 10 min until homogeneous; 40 mL of the above CNTs dispersion was added and stirred at 300 r / min for 1.5 h, with the mixture being observed every 20 min using a glass rod; the mixture was placed in a vacuum drying oven and dried under vacuum. Degassing was performed at -0.09 MPa for 25 min to obtain cMWCNTs / PDMS premix.

[0047] (3) Preparation of BECP mixture: Add 2.2 g of berberine (pre-dissolved in 22 mL of anhydrous ethanol, concentration of 0.1 g / mL) to the premixed solution, stir at 300 r / min for 45 min, and observe with a fluorescence microscope (excitation wavelength 450 nm) to ensure that the berberine is uniformly dispersed.

[0048] (4) Substrate pretreatment: Glass fiber reinforced composite material (GFRP) was used. It was polished with 800-grit and 1200-grit sandpaper in sequence, ultrasonically cleaned with anhydrous ethanol for 20 min (power 200 W), and dried with nitrogen.

[0049] (5) Coating formation: The mixture was coated on the GFRP surface by dip coating (pulling speed 40 mm / min), the wet film thickness was controlled to be 80 μm, and cured in an oven at 95℃ for 5.5 h (heating rate 4℃ / min) to obtain a composite coating with a thickness of about 45 μm. After cooling to room temperature, it was ready for use.

[0050] Example 4: Actual marine antifouling performance test of berberine-modified cMWCNTs / PDMS composite coating

[0051] (1) Short-term sea-based plating experiment and microbial community analysis: The coating prepared in Example 1, along with the pure PDMS coating and the CNTs / PDMS coating (without berberine), were plating in the Xiaoshidao sea area of ​​Weihai. Samples were taken at 3, 15, and 24 days. 16S / 18S rRNA amplicon sequencing was used. The results showed that the relative abundance of Proteobacteria among prokaryotic microorganisms on the surface of the coating prepared in Example 1 was 38.2% (83.3% in the pure PDMS group), and the relative abundance of Diatoms among eukaryotic microorganisms was 17.5% (27.1% in the CNTs / PDMS group). The Shannon diversity index was reduced by more than 40% compared to the control group (e.g., ...). Figures 2-8 (As shown).

[0052] (2) Long-term marine antifouling experiment: The coating prepared in Example 1, along with the pure PDMS coating and the CNTs / PDMS coating (without berberine), were subjected to a long-term marine antifouling experiment in the Xiaoshidao waters of Weihai. The results showed that the berberine-modified cMWCNTs / PDMS composite coating exhibited excellent practical marine antifouling performance, with an antifouling period of up to 6 months (e.g., Figure 1 (As shown).

[0053] (3) Mechanical performance test: The tensile strength of the berberine-modified cMWCNTs / PDMS composite coating is 3.2 MPa (1.8 MPa for pure PDMS), and the adhesion grade is 1 (ASTM D3359 standard).

Claims

1. A berberine-modified carbon nanotube / polydimethylsiloxane antifouling composite coating, characterized in that... The composite coating is made of the following components by weight percentage: 85-90% polydimethylsiloxane (PDMS), 8-12% carbon nanotubes, and 1.5-2.5% berberine (BE).

2. The berberine-modified carbon nanotube / polydimethylsiloxane antifouling composite coating according to claim 1, characterized in that... The viscosity of the PDMS is 5000~8000 cSt, and the mass ratio of PDMS matrix to curing agent is 10:

1.

3. The berberine-modified carbon nanotube / polydimethylsiloxane antifouling composite coating according to claim 1, characterized in that... The carbon nanotubes are carboxyl-modified multi-walled carbon nanotubes (cMWCNTs) or carboxyl-modified single-walled carbon nanotubes (cSWCNTs).

4. The berberine-modified carbon nanotube / polydimethylsiloxane antifouling composite coating according to claim 3, characterized in that... The cMWCNTs have a length of 10-30 μm and a diameter of 20-50 nm.

5. The berberine-modified carbon nanotube / polydimethylsiloxane antifouling composite coating according to claim 1, characterized in that... The purity of the berberine 98%.

6. A method for preparing the berberine-modified carbon nanotube / polydimethylsiloxane antifouling composite coating according to any one of claims 1-5, characterized in that... The method includes the following steps: Step 1: Add carbon nanotubes to anhydrous ethanol and ultrasonically disperse them at a power of 300~500 W for 45~60 min to obtain a carbon nanotube dispersion with a concentration of 2~10 mg / mL. Step 2: Mix the PDMS matrix with the curing agent, add the carbon nanotube dispersion obtained in Step 1, and mechanically stir at 300~400 r / min for 1.5~2 h, followed by vacuum stirring. -0.09 MPa yielded a carbon nanotube / PDMS premix; Step 3: Add berberine to the premixed solution obtained in Step 2, and continue stirring for 30-60 minutes to ensure that the berberine is evenly dispersed, thus obtaining the BECP mixture; Step 4: Apply the BECP mixture obtained in Step 3 to the pretreated substrate surface and cure it at 90~100℃ for 5~6 hours to obtain an anti-fouling composite coating.

7. The method for preparing the berberine-modified carbon nanotube / polydimethylsiloxane antifouling composite coating according to claim 6, characterized in that... In step 4, the substrate pretreatment method is as follows: sanding with 800-grit and 1200-grit sandpaper in sequence, ultrasonic cleaning with anhydrous ethanol for 10-20 minutes, and drying with nitrogen; the coating method is dip coating or spray coating, the wet film thickness is 80-100 μm, and the dry film thickness is 45-60 μm.

8. The method for preparing the berberine-modified carbon nanotube / polydimethylsiloxane antifouling composite coating according to claim 6, characterized in that... The substrate is carbon steel, glass, polyethylene, 316L stainless steel, or glass fiber reinforced composite material.

9. The method for preparing the berberine-modified carbon nanotube / polydimethylsiloxane antifouling composite coating according to claim 6, characterized in that... The dipping method has a lifting speed of 40~50 mm / min, and the spraying method has a nozzle diameter of 0.5~0.6 mm and an air pressure of 0.3~0.4 MPa.

10. The application of the berberine-modified carbon nanotube / polydimethylsiloxane antifouling composite coating according to any one of claims 1-5 in the antifouling treatment of ship hulls, offshore platform legs, or marine aquaculture cages.

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