Marine Field Tests Research Articles

Synthesis and characterization of waterborne polyurethane‐based marine antifouling coating modified via glycerol laurate

AbstractMarine biofouling is a major international challenge since it is responsible for several environmental problems and economic losses. Developing a novel antifouling coating with good water resistance, adhesion, and controlled degradation performance is crucial to solving the problem. Herein, a series of waterborne polyurethane emulsions were synthesized using the prepolymerization chain expansion and self‐emulsification method, with varying contents of glycerol laurate (GL) as the post‐chain extender. The findings demonstrated a notable enhancement in the controllable degradation performance, adhesion, marine antifouling properties, and water resistance with an increase in the concentration of GL. In particular, the film exhibited the most optimal overall properties when the introduction amount of GL was 2 wt%. The absorption rate of the artificial seawater (ASW) reached a state of equilibrium when GWPU2 was immersed in ASW for 60 days, with a final value of approximately 18.5%. The release rates of the GWPU2 antifouling coatings were observed to be the lowest at approximately 120 days, with a rate of approximately 37.59 μg/cm2/day. The long‐term antifouling capability of the GWPU resins was demonstrated in marine field tests, wherein they exhibited sustained antifouling activity for a period exceeding 9 months. In particular, GWPU2 exhibited noteworthy antifouling performance.

A type of multifunctional cellulose nanocrystal composite silicone-based polymer coating for marine antibiofouling

Nanocomposite polymer coatings are being used as a new generation of marine antibiofouling coatings because of their toxin-free chemical composition and ease of large-scale adoption. Cellulose nanocrystal (CN) exhibits significant potential for composite reinforcement. Herein, CN was surface-modified via α,ω-bis(3-(2-hydroxyl-terminated polydimethylsiloxane (HTPDMS), resulting in dihydroxyl-terminated poly(dimethylsiloxane)-grafted CN (HP-g-CN). The amine-terminated PDMS as the foundational component was sequentially reacted with isophorone diisocyanate, isophthalaldehyde, and carbon disulfide to produce PDMS-based poly (urea-thiourea-imine) (PDMS-PUTI). Subsequently, a composite (PDMS-PUTI/HP-g-CN) was produced through physical blending. The intrinsic imine bonds and dynamic hydrogen-bonding network were responsible for the self-healing properties, which achieved a healing efficiency of up to 89.2 %. HP-g-CN was grafted with the non-leaching lubricant, HTPDMS, resulting in improved mechanical properties (1.38 MPa of ultimate strength) and adhesion strength (2.43 MPa), along with the self-cleaning and self-lubricating performance (0.700 coefficient) of the coating. Additionally, the fouling resistance to bovine serum albumin (BSA, 10.44 μg cm−2), bacteria (∼97.08 % and ∼ 98.05 % reduction for Pseudomonas sp. (P. sp.) and Shewanella sp. (S. sp.), respectively), and diatoms (∼27 cells mm−2) was further enhanced. Marine field tests conducted over 90 days revealed that the coatings were static fouling-resistant for an extended period. This study demonstrated a multifunctional, high-performance, and environmentally friendly nanocomposite polymer coating for preventing marine biofouling.

A novel strategy for design of mechanically robust antifouling coatings via bifunctional domain engineering

The issue of biofouling on marine structures carries significant economic and ecological implications, necessitating the development of effective and durable antifouling coatings. Traditional organic antifouling coatings often struggle with mechanical robustness in harsh marine environments, making them fragile and highly susceptible to abrasion. To address these challenges, we propose a novel “bifunctional domain engineering” strategy for designing robust antifouling coatings that combines excellent mechanical strength of a Fe-based amorphous layer and high antifouling efficacy of an incorporated organics. The hard domains consist of Fe-based amorphous micro humps, providing a sturdy framework that enhances the coating's mechanical durability. In contrast, the soft domains comprise epoxy resin infused with Cu2O and 4,5-Dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT), offering a dual-action antifouling function via controllable antifouling agent release. Evaluation of antifouling performance by lab tests against Pseudomonas aeruginosa, Staphylococcus aureus, and Chlorella algae and practical marine field tests (for 150 days) demonstrates significant reductions in bacterial and algal adhesion (nearly 100 % resistance) with the bifunctional domain engineered coating (referred to as HSR coating), compared to pure amorphous coating. Mechanical durability tests, including abrasion and erosion experiments, underscore the HSR coating's excellent wear resistance. Importantly, the HSR coating maintains its outstanding antifouling properties even after 1000 abrasion cycles, highlighting its potential for long-term marine applications in harsh conditions. This study lays the groundwork for design of robust antifouling coatings capable of withstanding the harsh operating environments while effectively combating biofouling.

Enhanced antifouling capability of PDMS/Cu2O-anchored Fe-based amorphous coatings

Biofouling and corrosion, caused by marine organisms, pose significant challenges in the marine industry. Fe-based amorphous coatings have demonstrated remarkable corrosion resistance and hold promise for marine applications. However, they lack sufficient antifouling properties. Herein, we present a novel approach to enhance the antifouling properties of Fe-based amorphous coatings through co-modification with polydimethylsiloxane (PDMS) and cuprous oxide (Cu2O). The PDMS/Cu2O antifouling layer was successfully applied to the Fe-based amorphous coating with the bonding strength exceeding 2 MPa. The PDMS/Cu2O- anchored Fe-based amorphous coating (designated as PCA coating) demonstrates outstanding antifouling performance, showcasing 83.9 % resistance to protein, 99 % resistance to algae, high resistance to bacteria and mussel adhesion, and successful antifouling performance in practical marine field tests. The remarkable antifouling properties of the PCA coating stem from its dual capacity of killing and resisting to deter organism attachment across different length scales. And the enhanced anti-corrosion performance of the PCA coating was verified through electrochemical impedance spectra (EIS). This study presents an innovative approach to designing marine coatings with anti-fouling and anti-corrosion capabilities.

Eco-friendly marine antifouling coating consisting of cellulose nanocrystals with bioinspired micromorphology

Nanomaterial-incorporated surfaces with microstructures have been widely used for marine antifouling coatings, yet limited green antifouling coatings are currently available for sustainable application, given the potential environmental effects of nanomaterial-based nanofillers. Here, by using natural sourced nanomaterials (cellulose nanocrystals, CNCs) as nanofillers, a nanocomposite superhydrophobic coating was fabricated via a simple sol-gel synthesis method. Notably, CNCs were firstly applied in the marine antifouling realm to form uniform and stable coatings, which were condensed with hydroxyl groups of hydrolyzed tetrapropyl zirconate, 3-glycidyloxypropyltrimethoxysilane, and methyltrimethoxysilane. The synthesized coatings gained a biomimetic microscopic ridge-like surface, where more CNCs contents contributed to finer microstructures. As a result of the influence of CNCs content on surface wettability and antifouling properties, the coating with CNCs accounting for 20 wt% of the total solid content (CNC20) delivered the best antifouling performance. Furthermore, 90-day marine field tests verified CNC20's excellent antifouling ability, reducing fouling by 82 % in comparison to the control group. Such a biomimicry study provides a novel strategy for the development of environmentally friendly coatings with CNCs nanofillers.

Synthesis and Properties of Self-Polishing Antifouling Coatings Based on BIT-Acrylate Resins

Painting antifouling coatings is one of the most important methods to prevent marine biofouling. Acrylic resin is widely used in marine antifouling because of its excellent stickiness, water resistance, and film-forming capabilities. At present, the widely used acrylate antifouling coatings require a high concentration of cuprous oxide as antifoulant. The release and accumulation of copper ions are the main factors affecting the marine environment. In this study, BIT–allyl methacrylate (BM) and zinc acrylate (ZM) were selected as functional monomers copolymerized with methyl methacrylate (MMA) and butyl acrylate (BA) to prepare a series of BIT acrylate antifouling resins. The inhibitory effects of all resins against marine bacteria (S. aureus, V. coralliilyticus, and V. parahaemolyticus), marine algae (Chlorella, I. galbana, and C. curvisetus), and barnacle larvae were studied. Moreover, marine field tests on the BIT modified resin in coastal waters were conducted. The results demonstrate that the grafted BIT–zinc acrylate resin not only exhibits excellent antifouling properties but also a significant self-polishing performance, providing a novel strategy to design a long-term antifouling resin with stable antifoulant release.

Preparation and Properties of Environmentally Friendly Marine Antifouling Coatings Based on a Collaborative Strategy.

Long-term and green marine antifouling coatings are an important means to prolong the service life of ships and other marine instruments and equipment. To accomplish this, we prepared three new green and high-efficiency antifouling coatings containing phthalimide derivatives inspired by capsaicin (PDIC-AC) by using a collaborative strategy that incorporates self-polishing, fouling repelling, and antifouling properties. Static simulation tests confirmed that the zinc acrylate resin of the PDIC-AC has excellent self-polishing properties due to changes in the roughness, surface free energy, and mass loss. Antifouling tests demonstrated that both PDIC and PDIC-AC possess efficient antibacterial and anti-algal effects. Moreover, marine field tests showed that the PDIC-AC are highly antifouling for at least 9 months, and their antifouling effect is similar to that of an antifouling coating with chlorothalonil (CT-AC). The collaborative strategy in this study can be used to research and develop long-term environmentally friendly antifouling coatings.

Excellent synergistic antifouling polymers based on controlled release of cinnamic acid and hydrolysis-induced fluorinated micro/nanostructure

A new type of acrylate zinc fluorinated polymer (AZFP) is designed and successfully prepared through grafting basic zinc 4-hydroxycinnamate onto the side chain of acrylate fluorinated polymers via dehydration reaction. The Zn(II) (COO–Zn–COO) in the polymer can hydrolyze in seawater so as to slowly release green antibacterial p-coumaric acid (p-CA) and simultaneously expose hydrophobic fluorinated side chains to form a fluorinated micro/nanostructure surface with excellent antifouling properties. In addition, lab results reveal that fouling organisms such as E. coli, bovine serum albumin (BSA), and chlorella are hard to adhere to and colonize on the polymer surface. Significantly, marine field tests demonstrate that the polymer has an excellent static anti-biofouling performance for over 240 days without resorting to adding any biocidal or toxic agents. This work provides a novel synergistic strategy for coordinating multiple green antifouling mechanisms to work together effectively, which would aid the development of environmentally friendly antifouling polymers.

A switchable zwitterionic ester and capsaicin copolymer for multifunctional marine antibiofouling coating

In this work, a multifunctional marine antibiofouling coating was prepared by covalently grafting switchable zwitterionic ester and capsaicin copolymers onto the polydimethylsiloxane (PDMS) network in a one-pot reaction. Zwitterionic esters could kill bacteria via their positive charge and release dead bacterial cells after hydrolysis to antifouling zwitterionic moieties. Meanwhile, chemically conjugated capsaicin molecules could also be sustainedly released via hydrolyzation to repel marine organisms. Compared with the pristine PDMS matrix, the hydrolyzed coating reduced protein adhesion by 88.5%, bacterial adhesion by 99.0%, and diatom adhesion by 99.5%. The adhesion force of pseudo barnacles was reduced by 72.4%. Marine field tests in the Yellow Sea further confirmed that the coating possessed excellent antibiofouling ability for at least 261 days. This study presents a promising strategy for the development of eco-friendly high-efficiency marine antibiofouling coatings.

Bioinspired Fatty Acid Amide-Based Slippery Oleogels for Shear-Stable Lubrication.

Liquid‐repellent technology is an efficient means of energy‐saving and biofouling avoidance. However, liquid‐repellent surfaces suffer from inefficient lubricant retention under shear flow and fouling problem in marine environment. Here, the authors demonstrate a fatty acid amide (FAA)‐based oleogel for stable and sustainable lubrication in marine environment. The lubrication management of marine creatures is emulated in synthetic oleogels by incorporating solid (FAA) and liquid lubricants into the molecular meshes of polymeric networks, with the nature‐derived solid lubricant providing multifunctional synergistic effects with liquid oil molecules for slippery property and remarkable anti‐biofouling. The lubricant‐confining gel achieves shear‐stable lubricity with efficient oil management. The oleogel provides continued lubrication without biofouling for approximately 4 months in marine field tests. The gel design provides a new paradigm for sustainable and shear‐stable lubrication in marine environment.

Research on electromagnetic wave absorption properties of zinc-based acrylate resins for marine antifouling coating

Here, we report on the marine antifouling performance and electromagnetic wave absorption (EMWA) properties of multifunctional zinc-based acrylate resins (ARZn-x). Their controlled hydrolysis with varying contents of carboxylic acid groups and ZnO led to formation of new surfaces that contributed to excellent antibacterial activity (>90%) and reductions in algal adhesion (optimal: 92.5%). Marine field tests demonstrated ideal antifouling performance during immersion in seawater for 4 months, and the coatings inhibited the adhesion and growth of biofouling species in marine. Furthermore, the ARZn-x resin coatings exhibited remarkable EMWA performance, with an RLmin of − 40.18 dB at 1.5 mm and 30.55 GHz, and full absorption of frequencies ranging from 18 to 40 GHz was achieved with thicknesses ranging from 1.0 to 5.5 mm. These resins provide new approaches to the development of multifunctional materials demonstrating marine antifouling performance and EMWA properties.

Preparation and evaluation of natural rosin-based zinc resins for marine antifouling

Currently, it is highly desirable to develop a novel antifouling resin with a controllable hydrolysis rate and stable and effective antifouling performance for marine antifouling coatings. In our study, we prepared natural rosin-based zinc (RZn-x) resins by a relatively facile and green synthetic method from Zn(OH)2 and antimicrobial natural rosin, which is considered a toxicity-free raw material, thus ensuring the green and antimicrobial character of the material. In their optimal combination, the RZn-x coating surface exhibited ideal peeling behaviour upon immersion in seawater, which caused the WCA of the material surface to change from 55° before immersion to 135° after immersion for 60 days and enhanced the antifouling properties. Dynamic simulation experiments of these resins also demonstrated that the hydrolysis rate of this material immersed in dynamic seawater was related to the zinc content, and we could control the self-polishing ability of the resins by adjusting the content of Zn(OH)2 participating in the reaction. Moreover, hydrolysis led to a hydrophobic surface, which could prevent fouling organisms from adhering. Laboratory bioassays against BSA adsorption (immersed for 4 h: 1.986 μg/cm2), bacterial (over 95 % reduction) and marine algal adhesion (more than 60 % reduction) revealed outstanding anti-protein, bacteriostasis and anti-algal growth and adhesion properties compared to pure rosin and the control sample. The long-term antifouling capability in marine field tests indicated that the RZn-x resins maintained their antifouling activity for more than 6 months, especially RZn-50, which showed excellent antifouling performance.

Urushiol titanium polymer‐based composites coatings for anti‐corrosion and antifouling in marine spray splash zones

AbstractSeawater is highly corrosive, and the alternating dry and wet environment can cause severe corrosion in metal equipment. Moreover, marine equipment is also seriously affected by marine biofouling. These harsh conditions pose a serious threat to the integrity of marine equipment as well as their associated maritime activities and necessitate the development of effective coatings to minimize damage to the equipment. Urushiol titanium polymer/acrylic resin (UTP/AR) composite materials were developed. Then, marine anti‐corrosion and antifouling coatings were prepared from the UTP/AR composite materials using rosin‐modified Cu2O as an antifoulant. The composite coating with a UTP:AR mass ratio of 1:1 (UTP/AR3) showed the best chemical resistance and light aging resistance. UTP/AR3 also exhibited a good corrosion current density (2.009 × 10−7 A cm−2) and corrosion potential (−0.5007 V), further indicating that the UTP/AR composite coatings have excellent anti‐corrosive properties. Marine field tests showed that the UTP/AR/Cu2O composite coatings with rosin‐modified Cu2O contents less than 20% showed stable, long‐term antifouling performance after immersion in seawater for 360 day. Briefly, the UTP/AR/Cu2O composite coatings have broad application prospects in the marine industry for materials in the spray splash zone.

Synthesis and Biological Activity of Acrylate Copolymers Containing 3-Oxo-N-allyl-1,2-benzisothiazole-3(2H)-carboxamide Monomer as a Marine Antifouling Coating.

A type of grafted acrylate copolymer resins, containing 3‐oxo‐N‐allyl‐1,2‐benzisothiazole‐2(3H)‐carboxamide monomer and heterocyclic monomers, was synthesized through the copolymeri‐ zation of methyl methacrylate (MMA) and butyl acrylate (BA) with functional monomers. The structures of the monomers and copolymers were validated by infrared (IR) and 1H nuclear magnetic resonance (NMR) spectroscopies. The inhibitory activities of the copolymers on algae, bacteria, and barnacle larvae were measured, and the antifouling potencies against marine macrofouling organisms were investigated. The results showed that the grafted resin had significant inhibitory effects on the growth of three marine algae (Isochrysis galbana, Nannochloropsisoculata, and Chlorella pyrenoidosa), and three bacteria (Vibrio coralliilyticus, Staphylococcus aureus,and Vibrio parahaemolyticus). The target copolymers also showed excellent inhibition of the survival of barnacle larvae. Additionally, the release rate of the antifoulant and the results of the marine field tests indicated that the grafted copolymers had outstanding antifouling potency against the attachment of marine macrofouling organisms.

Synergistic effect of copolymeric resin grafted 1,2-benzisothiazol-3(2H)-one and heterocyclic groups as a marine antifouling coating.

In order to find a new type of antifouling coating with higher biological activity and more environmental protection, heterocyclic compounds and benzisothiazolinone were introduced into acrylic resin to prepare a new type of antifouling resin. In this study, a series of grafted acrylic resins simultaneously containing benzoisothiazolinone and heterocyclic monomers were prepared by the copolymerization of an allyl monomer with methyl methacrylate (MMA) and butyl acrylate (BA). Inhibitory activities of the copolymers against marine fouling organisms were also investigated. Results revealed that the copolymers exhibit a clear synergistic inhibitory effect on the growth of three seaweeds: Chlorella, Isochrysis galbana and Chaetoceros curvisetus, respectively, and three bacteria, Staphylococcus aureus, Vibrio coralliilyticus and Vibrio parahaemolyticus, respectively. In addition, the copolymers exhibited excellent inhibition against barnacle larvae. Marine field tests indicated that the resins exhibit outstanding antifouling potency against marine fouling organisms. Moreover, the introduction of the heterocyclic group led to the significantly enhanced antifouling activities of the resins; the addition of the heterocyclic unit in copolymers led to better inhibition than that observed in the case of the resin copolymerized with only the benzoisothiazolinone active monomer.

Inhibition of Marine Biofouling with Degradable Copolymer

Hou, X.; Sun, W.; Luo, Q.; Zhang, S., Huang, S., 2020. Inhibition of marine biofouling with degradable copolymer. In: Yang, D.F. and Wang, H. (eds.), Recent Advances in Marine Geology and Environmental Oceanography. Journal of Coastal Research, Special Issue No. 108, pp. 178–182. Coconut Creek (Florida), ISSN 0749-0208.Degradable copolymers are promising materials for marine antibiofouling as the resource and environmental problems become more and more serious. Degradable copolymer poly(-caprolactone-co-tert-butyl methacrylate) was synthesized with organic catalyst. The presence of the poly(-caprolactone) entries increases the erosion rates and reduce the swelling of the polymer film in the meantime. Poly(tert-butyl methacrylate) segments enhance the adhesion of the copolymer. Our study indicates that as the ester units in the backbone increase, the degradation rate increases but the swelling decreases in seawater. The degradation is controlled by the polymer composition or the molar ratio of the ester units. Marine field tests demonstrate that the degradable copolymers show good antibiofouling performance.

Terpolymer resin containing bioinspired borneol and controlled release of camphor: Synthesis and antifouling coating application

Marine biofouling can cause a biocorrosion, resulting in degradation and failure of materials and structures. In order to prevent sea creatures from attaching to the surface, in this work, a new environmentally friendly antifouling coating by incorporating antibacterial polymers and natural antifouling agents has been designed and synthesized. Surface chemical composition and changes in surface hydrophobicity were studied by FTIR spectroscopy and contact angle measurements, respectively. Measurements of mass loss of antifouling resin were also carried out and the release rate of camphor from antifouling coating was tested by using UPLC. It had been found that the changes in the content of triisopropylsilylacrylate (TIPSA) (from 4% to 12%) and isobornyl methacrylate (IBOMA) (from 50% to 16.7%) did not significantly affect the release of camphor. The content of IBOMA decreased from 50% to 16.7%, the antifouling performance of the resin system appeared slightly reduced. In addition, rosin could help regulate the release rate of the resin system to desorb camphor slowly in water in a controlled manner. Furthermore, the antifouling capability of as-prepared samples was evaluated via algae suppression experiments and marine field tests. This study highlighted the environmentally friendly antifouling coating as a potential candidate and efficient strategy to prohibit biofouling in seawater.

Fluorinated diols modified polythiourethane copolymer for marine antifouling coatings

The development of environmentally friendly alternatives is a crucial issue, since the prohibition of tributyltin (TBT)-based antifouling coatings. In this work, a series of fluorinated diols modified polythiourethane (HO-FPTU-x) have been synthesized via a simple and convenient polymerization reaction with HDI, PETMP and various of 2,3,5,6-tetrafluoro-1,4-benzenedimethanol (HOCH2-FB-Al) at the room temperature, and their antifouling properties are explored as well. The laboratory assays and marine field tests (6 months) show that the HO-FPTU-7.5 (with 7.5 wt% HOCH2-FB-Al) coating has shown excellent antifouling/fouling release properties. The side chains of the HO-FPTU polymers simultaneously contain hydrophobic and hydrophilic groups, which construct an “ambiguous’’ surface after immersing into water. The marine organisms may be “confused’’ by the “ambiguous’’ surface and be removed easily during settlement and adhesion. This work provides a facile strategy for designing environment friendly marine antifouling coatings.

Highly Branched Copolymers with Degradable Bridges for Antifouling Coatings.

The antifouling properties of traditional self-polishing marine antifouling coatings are mainly achieved based on their hydrolysis-sensitive side groups or the degradable polymer main chains. Here, we prepared a highly branched copolymer for self-polishing antifouling coatings, in which the primary polymer chains are bridged by degradable fragments (poly-ε-caprolactone, PCL). Owing to the partial or complete degradation of PCL fragments, the remaining coating on the surface can be broken down and eroded by seawater. Finally, the polymeric surface is self-polished and self-renewed. The designed highly branched copolymers were successfully prepared by reversible complexation mediated polymerization (RCMP), and their primary main chains had an Mn of approximately 3410 g·mol-1. The hydrolytic degradation results showed that the degradation of the copolymer was controlled, and the degradation rate increased with increasing contents of degradable fragments. The algae settlement assay tests indicated that the copolymer itself has some antibiofouling ability. Moreover, the copolymer can serve as a controlled release matrix for antifoulant 4,5-dichloro-2-octylisothiazolone (DCOIT), and the release rate increases with the contents of degradable fragments. The marine field tests confirmed that these copolymer-based coatings exhibited excellent antibiofouling ability for more than 3 months. The current copolymer is derived from commonly used monomers and an easily conducted polymerization method. Hence, we believe this method may offer innovative insights into marine antifouling applications.

Environmentally Friendly Marine Antifouling Coating Based on a Synergistic Strategy.

The development of environmentally friendly and long-term marine antifouling coating remains a huge challenge in the maritime industry. For this purpose, we developed a novel and efficient antifouling coating based on a synergistic strategy, incorporating contact inhibition, fouling repelling, and antifouling properties. Results demonstrated that the coating could efficiently resist the adhesion of protein, bacteria, and Navicula diatoms. More importantly, marine field tests showed the coating could efficiently inhibit biofouling for at least 8 months. This approach paves a new way for the development of environmentally friendly and long-term antifouling coating.