Marine Field Test Research Articles

A bio-inspired liquid-like smooth copolymer coating with superior biofouling resistance and drag reduction

The marine biofouling and fluid resistance have a detrimental impact on underwater vehicles. It is essential to develop functional material integrated with both antifouling and drag reduction effects for maritime transportation and navigation. Herein, to avoid the disadvantages of common slippery liquid-infused surfaces, such as the complexity of preparation micro/nanopores and the depletion of the lubricant layer, the novel liquid-like coating was fabricated by integrating the synthesized long chain organosilicon monomer (HPSM) to the self-polishing polymer chains. It is that the ingenious design integrated anti-fouling and drag reduction functions. The surface composition and structure, mechanical properties, antifouling and drag reduction properties of the coating were characterized by FT-IR, XPS, SEM, μ-PIV. These results indicated that the unique monomer HPSM endowed the coating with unique liquid-like properties, including special wettability, viscoelasticity and extremely low roughness. The flexibility of HPSM promoted the self-adaption ability of the coating in the seawater environment, which can effectively either reduce the fluid resistance when the fluid flowed through the surface or the adhesion strength of the biofouling, such as lots of protein (BSA) and alga (Porphyridium sp.and Navicula sp.). Moreover, the synergistic effect between liquid-like properties and the interface renewal behavior of self-polishing components further strengthened the antifouling performance of the coating. The marine field test further indicated the comprehensive anti-fouling performance and mechanical stability of the coating in practical application scenarios. This research provided a facile approach for preparing antifouling and drag-reduction coating. Therefore, it was believed to be a great inspiration for the design of functional coating against biofouling and drag reduction in the ship and marine industry field.

Antifouling coatings based on the synergistic action of biogenic antimicrobial agents and low surface energy silicone resins and their application to marine aquaculture nets

Aquaculture nets used in seawater for a long time are susceptible to biofouling, and antifouling coatings are a cost-effective way to solve this problem. In this study, biogenic antimicrobial components were extracted from two plants, Houttuynia and Scutellarin, and modified with methylphenyl silicone resin (MSR) by physical blending. Two flexible antifouling coatings with synergistic action of biogenic antimicrobial agents and low surface energy silicone resin for marine aquaculture nets were prepared separately. The prepared coatings retained the low surface energy properties of silicone resin: the contact angles (CA) were all over 130°, and the surface energy (SE) were all below 1.5 mN/m. Meanwhile, the coatings with Houttuynia and Scutellarin additives showed inhibition rates of more than 90 % against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), and more than 50 % against Chlorella vulgaris. Marine Field Test showed that the coatings containing Scutellarin and Houttuynia additives reduced fouling adhesion by 17.24 % and 35.92 %, respectively, compared with Ultra-high molecular weight polyethylene (UHMWPE) net coats without any additives. This study provides an efficient and environmentally friendly solution for antifouling treatment of marine aquaculture nets, which is of positive significance for enhancing the sustainable development of Marine Ranching.

Development of a mechanically robust silicon-based cross-linking polymer for the sustainable marine antifouling coatings

Silicone-based fouling release coatings (FRCs) have shown great promise as an environmentally friendly antifouling technology, while inferior mechanical properties and insufficient substrate adhesion have hindered their further application. We focused on enhancing the mechanical robustness of silicone-based coating through the synergistic effects of hydrogen bonding, π-π aromatic interaction and covalent bonding. The resulting silicone-based coating displayed a low surface energy of 23 mJ/m2 and improved mechanical strength and substrate adhesion, offering values up to 6.4 MPa (9.1 times higher) and 2.87 MPa (25.7 times higher), respectively. Additionally, the modified coating demonstrated a tear strength of 9.8 kN/m and mass loss only about 30 mg after enduring 10,000 wear cycles. Alkoxysilane-functionalized polyethylene glycol and quaternary ammonium salt were grafted into the cross-linking structure to make them anchored to the networks and migrated to the surface layer in seawater without releasing. The coating provided 99.1% antibacterial efficiency and effective antidiatom performance (≤ 11.2 cell/mm2). After a 12-month marine field test, the developed film showed only 20% micro bio-fouling compared to 100% fouling coverage on the PDMS surface. By combining improved mechanical properties with antifouling characteristics, this new multifunctional silicone-based FRC exhibits tremendous potential for sustainable marine antifouling coating application.

Multi-strategy combined bionic coating for long-term robust protection against marine biofouling

Polyurethane-fluorinated polysiloxane (PU-FPDMS) with high-strength, high-bonding and low surface energy is synthesized as the matrix, and the PU-FPDMS/MCs/Ag marine anti-fouling coating on the surface of imitation crab shells is constructed by assembling butenolide@1,1-stilbene-modified hydrolyzed polyglycidyl methacrylate/graphene oxide microcapsules (Bu@PGMAm/GO MCs) with compact multi-shell structure and Ag nanoparticles (AgNPs) step by step on the PU-FPDMS matrix. The PU-FPDMS/MCs/Ag bionic anti-fouling coatings achieve long-term and stable anti-fouling effect under the combination of robust low-surface-energy PU-FPDMS matrix, steady-state sustained release of butenolide encapsulated by the compact multi-shell, bionic surface formed by the microcapsules and AgNPs, and the release of Ag+. The shear strength, tensile strength, and elongation at break of the PU-FPDMS/MCs/Ag are 3.53 MPa, 6.7 MPa, and 192.83 %, respectively. Its static contact angle and sliding angle are 161.8° and 3.6°, respectively. The antibacterial rate of PU-FPDMS/MCs/Ag against Escherichia coli, Staphylococcus aureus, and Candida albicans can reach 100 %. Compared with glass blank, PU, PU-FPDMS, PU-FPDMS/Ag, and PU-FPDMS/MCs, both the adhesion number and coverage percentage of chlorella adhere to PU-FPDMS/MCs/Ag are the minimum values, which are 600 cell mm–2 and 1.53 %, respectively. After 6 months of marine field test, the primer blank, PU, PU-FPDMS all show different degrees of attachment by shellfish, spirorbis, algae and other biofouling, while the PU-FPDMS/MCs/Ag coating is still not covered with biofouling, while the PU-FPDMS/MCs/Ag coatings still exhibit little attachment of marine fouling. The PU-FPDMS/MCs/Ag bionic anti-fouling coatings are expected to be widely used in the fields of anti-fouling, anti-icing, anti-fogging, drag reduction, self-cleaning, and antibacterial.

Hydrogel-Anchored Fe-Based Amorphous Coatings with Integrated Antifouling and Anticorrosion Functionality.

Biofouling and corrosion of underwater equipment induced by marine organisms have become major issues in the marine industry. The superior corrosion resistance of Fe-based amorphous coatings makes them suitable for marine applications; however, they have a poor antifouling ability. In this work, a hydrogel-anchored amorphous (HAM) coating with satisfactory antifouling and anticorrosion performance is designed, utilizing an interfacial engineering strategy involving micropatterning, surface hydroxylation, and a dopamine intermediate layer to increase the adhesion strength between the hydrogel layer and the amorphous coating. The as-obtained HAM coating exhibits exceptional antifouling properties, achieving 99.8% resistance to algae, 100% resistance to mussels, and excellent biocorrosion resistance against Pseudomonas aeruginosa. Antifouling and anticorrosion performance of the HAM coating was also explored by conducting a marine field test in the East China Sea, and no signs of corrosion and fouling are observed after 1 month of immersion. It is revealed that the outstanding antifouling properties stem from the killing-resisting-camouflaging trinity that resists organism attachment across different length scales, and the excellent anticorrosion performance originates from the remarkable barrier of the amorphous coating against Cl- ion diffusion and microbe-induced biocorrosion. This work presents a novel methodology for designing marine protective coating with excellent antifouling and anticorrosion properties.

Non-silicone elastic coating with fouling resistance and fouling release abilities based on degradable hyperbranched polymer

Developing eco-friendly antifouling materials for combating marine biofouling has long been a challenging task. Herein, we report a non‑silicone elastomer coating based on hyperbranched poly (ε-caprolactone) (HPCL) cross-linked with an amphiphilic triblock copolymer of poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol). The polymer coating is prepared by ring-opening polymerization and self-condensation reactions, which can be prepared at a large scale. Such a coating is expected to have a self-renewed surface, fouling resistance and fouling release abilities. Quartz crystal microbalance with dissipation test shows that the coating is degradable, leading to a self-renewed surface. The degradation rate can be regulated by adjusting the HPCL content. Bioassays with bacteria (Staphylococcus aureus and Escherichia coli) and diatom (N. incerta) reveal that the surface with triblock copolymer content of 12.5 wt% or higher can resist the adhesion of microorganisms. The coating also has good fouling release performance with pseudobarnacle removal strength of ∼0.15 MPa, which is comparable with that of silicone elastomer. Marine field test for over 120 days proves the coating is effective in inhibiting marine biofouling due to the synergetic effect of surface renewal, fouling release and fouling resistance. This work provides a facile preparation method for biocide-free antifouling materials.

A Cu2O-based marine antifouling coating with controlled release of copper ion mediated by amphiphilic PLMA-b-PDMAEMA copolymers

To achieve prolonged and sustainable release of copper ion in Cu2O-containing marine coatings, poly(lauryl methacrylate)-b-poly(2-(N,N-dimethylamino)ethyl methacrylate) (PLMA-b-PDMAEMA) diblock copolymers with different block ratios and molecular weights were synthesized by atom-transfer radical polymerization (ATRP) method. It was proved that the copolymers are able to coordinate with copper ion. And the surface wettability tests showed that the amphiphilic copolymers may undergo structure change in seawater. Taking advantage of the structure transformation and copper coordination abilities, the copolymer was employed to encapsulate Cu2O for the preparation of antifouling coatings. A controllable and continuous release of copper ion from Cu2O/copolymer coatings was then obtained. More importantly, it showed that higher PLMA/PDMAEMA block ratio exhibited better bactericidal rate. Actually, the bactericidal ability of the coating depends on the time duration of copper ion on the surface instead of the hydrolysis speed of the coating, in other words, the hydrophobic interaction of PLMA with the resin may play a major role in the antifouling performance of the marine coating. Self-polishing coatings Cu2O/copolymer/polycaprolactone (PCL) were then prepared and applied for marine field test, the antifouling performances were proved to be comparable to that of the commercially available self-polishing coatings.

Environmentally benign smart self-healing silicone-based coating with dual antifouling and anti-corrosion properties

Marine corrosion and biofouling on metallic materials are sticky problems in maintenance of various vessels and facilities in the ocean. Further, designing of an eco-friendly marine coating with both antifouling and anti-corrosion properties has remained a significant challenge in marine field. The present study aimed to develop a novel smart self-healing silicone-based coating with dual antifouling and anti-corrosion properties was through disulfide exchange reaction between the functionalized monomer “lipoic acid-benzothiazole” (LA-BTZ) and LA modified polydimethylsiloxane (PDMS) based polyurea-urethane (PDMS-PUU-LA). Multiple dynamic bonds in backbone, flexible disulfide bonds, and strong cross-linked hydrogen bonds ensure the PDMS-based polymer with good toughness (2.58 MPa of ultimate strength), high stretchability (1014.7%), and self-healing properties. It was found that the scratches on the film in air completely disappeared within 40 min at room temperature. The time required for the healing efficiency of strength ranged between 98.5 and 94.6% under ambient condition and artificial seawater was only 4 and 8 h, respectively. The adhesion strength of silicon-based coating to epoxy resin and steel substrate was ∼ 2.50 and ∼ 3.33 MPa, respectively. In addition, results of laboratory bioassays and marine field test of 120-day demonstrated that coating without any additional toxic biocides in the present study had long-term static fouling-resistant properties. Electrochemical impedance spectroscopy (EIS) measurements and salt spray test showed that the PDMS-PUU-TZ-3 coating exhibited the better corrosion resistance. Therefore, the current work presented a novel eco-friendly smart silicone-based coating for marine antifouling and anti-corrosion.

Hagfish‐inspired Smart SLIPS Marine Antifouling Coating Based on Supramolecular: Lubrication Modes Responsively Switching and Self‐healing Properties

AbstractSlippery liquid‐infused porous surface (SLIPS) has received widespread attention in the antifouling field, while its controllability of surface lubricity and durability of lubricant are relatively insufficient. In this study, inspired by the hagfish's defensive behavior of secreting mucus to escape from predators, a smart SLIPS marine antifouling coating is prepared, which possesses responsively switching lubrication modes and self‐healing property. The responsive supramolecular interaction between azobenzene (Azo) and α‐cyclodextrin (α‐CD) is introduced to regulate the lubricity of SLIPS. cis‐Azo is converted to trans and combined with α‐CD by supramolecular interaction under visible light or heating, driving the shrinkage of polymer chains to squeeze the stored lubricant to the surface. The responsive self‐replenishment of lubricant can adjust the surface lubricity to switch antifouling modes between “enhancive” and “normal” smartly, which adapts to different occasions. Moreover, disulfide and hydrogen bonds are introduced to enhance self‐healing performance (91.73%). In summary, it has efficient self‐cleaning, anti‐protein, antibacterial, anti‐algae properties, and 180‐day real marine field antifouling performance during boom season (the longest antifouling period in real marine field test of reported SLIPS materials), which demonstrates the promising application in neritic sea equipment and other antifouling fields.

Synthetic Analogue of Butenolide as an Antifouling Agent.

Butenolide derivatives have the potential to be effective and environmentally friendly antifouling agents. In the present study, a butenolide derivative was structurally modified into Boc-butenolide to increase its melting point and remove its foul smell. The structurally modified Boc-butenolide demonstrated similar antifouling capabilities to butenolide in larval settlement bioassays but with significantly lower toxicity at high concentrations. Release-rate measurements demonstrated that the antifouling compound Boc-butenolide could be released from polycaprolactone-polyurethane (PCL-PU)-based coatings to inhibit the attachment of foulers. The coating matrix was easily degraded in the marine environment. The performance of the Boc-butenolide antifouling coatings was further examined through a marine field test. The coverage of biofouler on the Boc-butenolide coatings was low after 2 months, indicating the antifouling potential of Boc-butenolide.

Synthesis and application of indole esters derivatives containing acrylamide group as antifouling agents

Two new indole ester derivatives containing acrylamide group were synthesized by Michael addition reaction and Friedel-Crafts reaction based on 5-bromo-1H-indole. The synthesized compounds were characterized by 1H Nuclearmagnetic Resonance Spectroscopy (1HNMR) and Fourier Transform Infrared spectroscopy (FTIR). In the step of the Friedel-Crafts reaction, the optimum process conditions were determined as that the catalyst was AlCl3, the reaction time was 3 days and the reaction temperature was 25 °C. The results of minimal inhibitory concentration (MIC) of synthesized compounds showed that the two synthesized compounds have better antibacterial activity than reference. Algal inhibiting experiment shows that indole derivatives have better algae inhibition performance. Anti-protein adsorption experiment of antifouling paints with indole derivative and chlorothalonil as antifouling agents proves that indole derivatives exhibit better protein resistance behaviors. The antifouling paints using indole derivatives as antifouling agents have excellent antifouling properties after 24 months marine field test.

Eco-friendly erucamide–polydimethylsiloxane coatings for marine anti-biofouling

Marine biofouling of ship hulls and ocean structures causes enormous economic losses due to increased frictional drag. Thus, efforts have been exerted worldwide to eliminate biofouling. In addition, a strong demand exists for the development of a cost-effective and eco-friendly anti-biofouling coating technology. Thus, erucamide-polydimethylsiloxane (EP) coating is proposed in this study. EP exhibits a hydrophobic surface as the erucamide content and drag reduction effect increase. In this study, the drag reduction effect of the EP 2.5 is better than that of glass and polydimethylsiloxane (PDMS) surfaces. Moreover, the proposed EP coatings are observed to prevent the biofouling induced by bacteria (E. coli) and brown algae (Cladosiphon sp.). In addition, through a marine field test, the anti-biofouling effect of the EP surface is found to be better than the previously studied oleamide-PDMS (OP) surface. In the marine field test, the EP 2.5 demonstrates superior anti-biofouling performance for 5.5 months under real marine environment. The proposed eco-friendly EP coating method could be applicable to marine vehicles that require effective drag reduction and anti-biofouling properties.

Polyurethane coating with heterogeneity structure induced by microphase separation: A new combination of antifouling and cavitation erosion resistance

Cavitation erosion and biofouling are the most severe factors of metal materials fatigue failure and degradation in seawater. Herein, a series of hydrophobic fluorinated polyurethane coatings (SFPU-x) with various contents of fluorinated isocyanate prepolymer (FIP) were synthesized via a simple addition reaction for anti-cavitation erosion property combined with biofouling resistance. The microstructure and phase composition of as prepared coatings were analyzed by ATR-IR, SEM, TG, EDS and AFM. The addition of FIP increases the content of hard segments microregion and affects the microphase separation of the coating and induces the construction of surface heterogeneity microstructures. The static water contact angle and water absorption were measured as well. The antifouling tests were conducted using Nitzschia Closterium cell and the fluorescence labeled bovine serum albumin (FITC-BSA) as fouling models. Especially, the SFPU-5 coating with 5% FIP shows excellent antifouling and cavitation erosion resistance abilities due to surface heterogeneity microstructure, the attachment rates of FITC-BSA (1.1 %) and Nitzschia cell (1.3 %) far less than that of SFPU-0 coating (72.3 % and 85.1 %), respectively. Marine field test for 30 days also proven the antifouling properties of the SFPU-5 coating. In addition, there were no obvious holes and cracks on the surface of SFPU-5 after 10 h of cavitation, the cumulative mass loss were 2.7 mg and 2.9 mg in deionized water and in seawater, respectively.

A polyvinylpyrrolidone-based surface-active copolymer for an effective marine antifouling coating

Currently, it is highly desirable to develop a stable and effective antifouling coating in maritime industries. In this work, a novel surface-active copolymer basing on hydrophilic polyvinylpyrrolidone (PVP) and hydrophobic poly(dimethylsiloxane) (PDMS) was designed and incorporated into a crosslinked PDMS matrix to form a surface-renewable antifouling coating. In the copolymer, PVP segments possessed a chemical stability and could prevent the settlement of fouling organisms attributable to its strong hydrophilicity; PDMS endowed the copolymer with compatibility to PDMS matrix and could efficiently reduce the fouling adhesion strength attributable to the low surface energy. Based on the surface-active copolymer, the coating could be reconstructed underwater in response to the environment forming a renewable surface to promote the fouling-release property. In addition, a set of controllable composition coatings were prepared to investigate the effects of surface chemistry on antifouling and fouling-release performance. Laboratory bioassays against marine unicellular diatom adhesion (∼99 % reduction) and mimetic barnacle attachment (∼81 % reduction) demonstrated an outstanding antifouling and fouling-release property of the copolymer-based coating compared to pristine PDMS, and the coating with a higher PVP content exhibited a better performance. Moreover, a long-term antifouling capability in marine field test (∼4 months) was also demonstrated. This work may offer a promising solution to the problems induced by marine biofouling.

Self-polishing emulsion platforms: Eco-friendly surface engineering of coatings toward water borne marine antifouling

Biofouling has been a great challenge for the exploitation of marine resources and could be generally avoided by decorating with protective coatings on the ships or equipment, while the process will produce a great amount of volatile organic compounds (VOC) and lead to or even aggravate environmental hazards. A high-performance water borne antifouling coating (WBAC) composed of self-polishing emulsion and bioactive ingredient was prepared, in which triisopropylsilyl ester acted as the self-polishing matrix and zwitterionic complex with cupric ion was used as the main antifoulant. The surface wettability, self-polishing rate, essential mechanical properties and the broad-spectrum antifouling capability were characterized in the lab. The experimental results indicated that the designed fully solvent free coating was capable of adjustable polishing rate and possessed robust stability and excellent antifouling performance for the settlement of green algae, red algae and diatom. Moreover, the long-term but robust performance of the engineered WBACs has been proved in the marine field test. Considering its solvent-free character and excellent antifouling behavior, this research would provide insights into the design of the next-generation of the eco-friendly and sustainable marine antifouling coating.

Marine field test for steel reinforcement embedded in mortar: Coupled influence of the environmental conditions on corrosion

This paper studied the environmental conditions and corrosion behaviour of mortar samples at two different marine tidal zones and investigated the correlation among the environmental conditions, corrosion rates, and corrosion products. From the experimental results, the concrete structure damage is a function of numerous correlated factors such as the temperature, humidity, and corrosion products. The chloride penetration rate increased by 15% when the humidity increased by 10% and temperature increased 4 °C. Chloride content is the main factor intensifying the reinforcement corrosion. Although the high temperature, humidity, and chloride concentration aggravate the early corrosion of reinforcement, the role of resultant corrosion products shows more important in the developing stage of corrosion damage. The resultant corrosion products affect further corrosion persistence in a complex way, because in some cases, corrosion products-caused cracks will promote corrosion, while in others, corrosion is reduced by sealing the pores with products.

A Self-Polishing Polyacrylate-g-polysiloxane Paint for Marine Antifouling Application

The polyacrylate-g-polysiloxane copolymers were prepared by condensation reaction of polyacrylate with polysiloxane. Nine different formulations of marine antifouling coatings based on TiO2 and polyacrylate-g-polysiloxane were fabricated. The coatings had strong adhesion to substrate due to the incorporation of main-chain acrylic moieties. The side-chain Si–O bonds from polysiloxane enable the copolymer to hydrolytically degrade, and provide a self-polishing character and the low surface energy to the copolymer coating. The performance of nine formulations was evaluated, and the Y7 coating exhibited hydrophobic, 6H pencil hardness and5B cross-cut adhesion. The properties of the Y7 coatings are substrate-independent. Antibacterial test and cytotoxicity test were conducted to verify that nano-TiO2 particles inside marine antifouling coating inhibited bacterial growth and enhanced anti-bio adhesion. The results of marine field test inartificial sea waters for six months reveal that the side-chains polysiloxane leads to a self-polishing, low surface energy surface and a better antifouling property.

Ni-advanced weathering steels in Maldives for two years: Corrosion results of tropical marine field test

Properties of rust films generated on Ni-advanced weathering steels in a tropical marine environment were investigated by various surface analysis and electrochemical techniques. The results show that corrosion rate of Ni-advanced weathering steels with different contents of Cu exposed for two years in Male Island is much higher than that in the marine atmosphere with lower level of chloride. Cu has no influence on the phase composition of rust films generated on different Ni-advanced weathering steel, but leads to discrepancy of corrosion resistance. Moreover, Ni-advanced weathering steels with different contents of Cu exhibit the combination of uniform corrosion and non-uniform corrosion, higher Cu content can impede the degree of non-uniform corrosion.

Degradable polyurethane based on triblock polyols composed of polypropylene glycol and ε-caprolactone for marine antifouling applications

Marine antifouling coatings require superior mechanical properties and effective antifouling. Degradable polyurethane (PU) coatings have a reputation for high performance. Degradable PU films were prepared by mixing triblock polyols [composed of polyether (polypropylene glycol or polyethylene glycol) and e-caprolactone] and crosslinker agent (tolylene diisocyanate trimer). The hydrolytic degradation and water absorption experiments of PU films demonstrated that the PU films could erode in artificial sea water, which were mainly controlled by the hydrophilic property of the polyether. Marine field test revealed that degradable polyurethane had excellent efficiency in preventing biofouling for more than 9 months.

“From the Nature for the Nature”: An Eco-Friendly Antifouling Coating Consisting of Poly(lactic acid)-Based Polyurethane and Natural Antifoulant

“From the nature, for the nature” is an instructive strategy to develop environment-friendly antifouling coatings. In this work, bio-sourced poly(lactic acid)-based polyurethane with hydrolyzable triisopropylsilyl acrylate (TSA) side groups has been prepared via thiol–ene reaction and polyaddition. Such a polymer exhibits high adhesion strength (∼2.0 MPa) and a controlled degradation rate tuned by varying its soft segment and TSA content. An environment-friendly coating is prepared with the polymer and an eco-friendly antifoulant (butenolide) derived from marine bacteria. Our study shows that butenolide can be released from the coating in continuous manner with a controlled rate as the polymer degrades in seawater. Digital holographic microscopy tracking analysis demonstrates that the coating can effectively inhibit the adhesion of marine bacteria Pseudomonas sp. Marine field test shows that such coating has excellent antifouling ability for more than 3 months.