Research on the Marine Antifouling Ability and Mechanism of Acrylate Copolymers and Marine Coatings Based on a Synergistic Effect

Marine biofouling is an urgent global problem in the process of ocean exploitation and utilization.In our work,a series of zinc-based acrylate copolymers(ACZn-x)were designed and synthesized using benzoic acid,zinc oxide(ZnO)and a random quaternion copolymer consisting of ethyl acrylate(EA),butyl acrylate(BA),acrylic acid(AA)and methacrylic acid(MAA)by free radical polymerization and dehydration condensation.The ACZn-x with a zinc benzoate side chain is able to hydrolyze in natural seawater under static conditions,resulting in the formation of a smooth surface.We investigated and confirmed the antifouling(AF)behavior of ACZn-x in the laboratory and revealed that they have better antibacterial(86%for S.aureus and 72%for E.coli)and anti-algal(≥60.1%for N.closterium and≥67.5%for P.subcordiformis)activities.We also assessed the marine AF properties of ACZn-x and corresponding coatings in Qingdao,China;the ACZn-x exhibited ideal AF properties with little silt and biological mucosa adhered to the ACZn-x surface after 6 months,and corresponding coatings exhibited little biofouling after 16 months in the ocean.Importantly,possible AF mechanisms were further proposed at the cellular level.These results could be helpful for the development and application of effective AF coatings.

Bionic Flexible Texture Design Based on Bio-Fouling Suppression Effect for Protection of Marine Structures

Marine equipments such as marine risers and oil pipelines operate in complex underwater environments and are usually attached by animals,plants and microorganisms.The attachment of marine fouling organisms will accelerate the corrosion damage of offshore structure and greatly reduce the service life.Studies have shown that non-smooth bionic surfaces with specific microstructures can inhibit fouling formation.Based on the idea of bionics,this paper proposes a new type of underwater flexible fretting texture,which is a composite material prepared by mixing graphene and silicone rubber,and modified by pulsed laser to construct a hexagonal bionic surface texture.Under the impact of specific water flow,the flexible texture can produce an angular displacement around 8°and a linear displacement in the amplitude range of 165μm,and the inhibition rate of fouling biological diatoms up to 97.5%,which can effectively avoid the occurrence of marine biological fouling.The results provide a new idea for the surface protection of marine structures,which is of great significance for the development of marine industry.

Review:Fabrication and Application of Zwitterion-based Functional Coatings

Zwitterion-based materials by virtue of their special physical and chemical characteristics have attracted researchers to utilize them for fabricating functional coatings. The simultaneous presence of positive and negative charges renders the zwitterion-based materials with electrostatically induced hydration properties, which enables a high resistance towards oily pollutants, nonspecific protein adsorption, bacterial adhesion and biofilm formation. This review starts from the working mechanism of zwitterions and covers the fabrication strategies of zwitterion-based functional coatings, namely the zwitterion-bearing binder route, the zwitterion-bearing additive route and the post-generation of coatings containing zwitterionic precursors. The applications of zwitterion-based functional coatings are discussed, including medical implants, marine antifouling and oil-resistant coatings, with focus on the relevant mechanisms of the zwitterion-containing coatings for a specific performance. Finally, some comments and perspectives on the current situation and future development of zwitterion-based functional coatings are given.

Biofilm inhibition mechanism of BiVO inserted zinc matrix in marine isolated bacteria

Biofilm plays an important role on microbial corrosion and biofouling in marine environments.Inhibiting biofilm formation on construction surfaces is of great importance.Photocatalytic material with visiblelight response,especially BiVO_(4),is regarded as a promising material for biofilm inhibition due to its green biocidal effect and high antibacterial efficiency.Approaches which can immobilize the photocatalytic particles onto metal surfaces with high mechanical strength are requisite.In this study,zinc matrixes were served as carriers for BiVO_(4)particles.The BiVO_(4)-inserted zinc matrixes were successfully obtained by ultrasound assisted electrodeposition.The insertion content of BiVO_(4)showed positive correlation with ultrasound power.Highly enhanced biofilm inhibition properties were obtained by BiVO_(4)inserted zinc·matrixes with an over 95%decreased bacterial coverage.It was proved that O2-(chief)andOH(subordinate)radicals were responsible for the high biocidal performance.Possible antibacterial mechanism was proposed,indicating that the photoinduced holes would both attack zinc crystals to generate active electrons to form O2-radicals,and react with H2 O to generate·OH,finally.Furthermore,corrosion resistance of the matrixes was proved to be stable due to the insertion of BiVO_(4).This study provides a potential application for photocatalyst in marine antifouling and anti-biocorrosion aspects.

Mechanically robust antifouling coating with dual-functional antifouling strategy by infiltrating PDMS into plasma-sprayed porous Al_(2)O_(3)-Cu coating

Marine biofouling is a worldwide challenge that needs to be solved urgently.Poly(dimethylsiloxane)(PDMS)-based fouling release coatings with low surface free energy(SFE)could effectively inhibit bio-fouling.Nevertheless,their poor mechanical durability,adhesive strength,and antifouling performance under static conditions significantly limit their applications.Herein,a novel mechanically robust Al_(2)O_(3)-PDMS-Cu composite coating with strong adhesive strength and remarkable antifouling performance was developed.The Al_(2)O_(3)-PDMS-Cu coating loaded with a small amount of Cu was fabricated by infiltrating PDMS into plasma-sprayed micro/nano-scaled porous Al_(2)O_(3)-Cu coating.Results showed that the fabri-cation of this Al_(2)O_(3)-PDMS-Cu coating did not alter the surface hydrophobicity and SFE of PDMS signif-icantly,thus presenting little influence on its inherent fouling release property.After rigorous abrasion test,the Al_(2)O_(3)-PDMS-Cu coating presented remarkably improved surface hydrophobicity due to the ex-posure of micro/nano structure,rather than falling offas that of PDMS coating.The combination of excel-lent abrasion resistance and one order of magnitude higher adhesive strength and hardness than PDMS coating contributed to the outstanding mechanical robustness of Al_(2)O_(3)-PDMS-Cu coating.Additionally,the antifouling assays against marine bacteria adhesion(95%reduction rate for Escherichia coli.(E.coli))and algae attachment(96%and 94%reduction rates for Chlorella and Phaeodactylum tricornutum(P.tricor-nutum),respectively after 21 days of incubation)demonstrated the superior antifouling performance of the Al_(2)O_(3)-PDMS-Cu coating.Thus,a high-performance Al_(2)O_(3)-PDMS-Cu antifouling coating with excellent mechanical robustness and long-term antifouling performance was achieved via the combination of me-chanical durability of Al_(2)O_(3)skeleton and the dual-functional antifouling strategy,i.e.,the fouling release property of PDMS and fouling resistance of Cu.

Durable self-polishing antifouling Cu-Ti coating by a micron-scale Cu/Ti laminated microstructure design

Marine biofouling is a major issue deteriorating the service performance and lifespan of marine infrastructures.The development of a durable,long-term,and environment-friendly antifouling coating is therefore of significant importance but still a critical challenge in maritime engineering.Herein,we developed a Cu-Ti composite antifouling coating with micron-sized alternating laminated-structure of Cu/Ti by plasma spraying of mechanically mixed Cu/Ti powders.The coating was designed to enable controlled release of Cu ions through galvanic dissolution of Cu laminates from the Cu/Ti micro-galvanic cell in aqueous solution.Results showed that remarkable antifouling efficiency against bacterial survival and adhesion up to~100%was achieved for the Cu-Ti coating.Cu/Ti micro-galvanic cell was in-situ formed within Cu-Ti coating and responsible for its Cu ions release.The successive dissolution of Cu laminates resulted in the formation of micro-channels under Ti laminates near surface,which contributed to controlled slow Cu ions release and self-polishing effect.Thus,environment-friendly antifouling capability and∼200%longer antifouling lifetime than that of the conventional organic antifouling coatings can be achieved for the Cu-Ti coating.On the other hand,as compared to the conventional organic antifouling coatings,the Cu-Ti composite coating presented much higher mechanical durability due to its strong adhesion strength,excellent mechanical properties,and two orders lower wear rate.The present laminated Cu-Ti coating exhibits combination of outstanding antifouling performance and high mechanical durability,which makes this coating very potentially candidates in marine antifouling application.

Facile fabrication of self-healing silicone-based poly(urea-thiourea)/tannic acid composite for anti-biofouling

A novel silicone-based poly(urea-thiourea)/tannic acid composite(PDMS-P(Ua-TUa)-TA)with excellent mechanical,self-healing and antifouling properties is developed.The multiple dynamic hydrogen bonds formed by thiourea groups,urea groups,and tannic acid(TA)molecules ensured a tough elastomer(ultimate strength:2.47 MPa)with high stretchability(~1000%).TA molecules as partial hydrogen bonding cross-linking sites interacted rapidly with urea and thiourea groups before the migration of polymer chains,resulting in fast and efficient self-healing.Scratches on the film completely disappeared within12 min,and the repair efficiency of strength was up to 98.4%within 3 h under ambient condition.Selfhealing behavior was also evaluated in artificial seawater and the healing efficiency(HE)was 95.1%.Furthermore,TA uniformly dispersed in the polymer matrix provides good antibacterial and anti-diatom properties,as well as strong adhesion to the substrate(~2.2 MPa).Laboratory bioassays against marine bacteria adhesion(~96%,~95%and~93%reduction for P.sp.,E.coli,and S.aureus,respectively)and diatom attachment(~84%reduction)demonstrated an outstanding antifouling property of the PDMSP(Ua-TUa)-TA.This work provides a promising pathway towards the development of high-performance silicone-based coatings for marine anti-biofouling.