Preparation Of Durable Antifouling And Anticorrosion Superwettable Coating In Marine Environments

Marine fouling,which results severe economic and ecological impacts in varieties of practical applications,has drawn more and more attention in recent years.Antifouling coating is one of the most effective solutions.However,most antifouling coatings tend to adsorb water,which greatly weakens the stability and anticorrosion of the coatings.Herein,a“Glue+Powder”strategy was used to prepare durable underwater composite coatings with antifouling,antibacterial and corrosion resistance on Al alloy by combining superhydrophobic undercoating and different finishing-coat,which greatly improved the stability and service life of the coating.In addition,the composite coating can be prepared in large scale by spraying due to its simplicity,low cost and universal adaptability to various substrates.The main contents are shown as follows:(1)Robust and durable superhydrophobic coating was prepared on aluminum alloy surface by“glue+powder”strategy with PDMS and hydrophobic Si O₂ nanoparticles.Due to its blocking barrier protection,the coating exhibited excellent immersion resistance and stability,and can provide effective and lasting protection to the substrate.(2)The underwater oil repellant coating with anti-fouling,antibacterial and corrosion resistance was fabricated on aluminum alloy by combining superoleophobic finishing-coat and superhydrophobic undercoating.The underwater superoleophobic finishing-coat can effectively inhibit the adhesion of oil molecules and the aggregation of microorganisms,while the superhydrophobic undercoating can greatly prevent the coating from absorbing water and falling off,thus delaying the corrosion of metal matrix.Immersion tests showed that the bifunctional coating didn't crack or peel after 30 days immersion in simulated sea water,indicating excellent durability in simulating seawater.Electrochemical tests demonstrated that the low frequency impedance was still more than 10⁹?cm² after 25 d of immersion,exhibiting excellent anticorrosion property.Antifouling test indicated that the coating could reduce the adhesion of oily molecules underwater and then refrain the formation of Pseudomonas sp.biofilm.(3)A p H-responsive releasing composite coating was prepared by combining the superhydrophobic undercoating and the finishing-coat containing chitosan(CS)microspheres.On the one hand,the excellent blocking barrier of superhydrophobic layer can prevent the coating from absorbing water and protect the metal matrix from corrosion;On the other hand,the protonation of chitosan was used to achieve the p H-sensitive release of the antibacterial agent,thus avoiding the loss and waste of the antibacterial agent and prolonging the service life of the coating.The results of DLS and UV-Vis analysis showed that the antimicrobial release of Bet@CS microspheres in acidic environment were significantly higher than that in neutral and alkaline environment.Electrochemical experiment results showed that the composite coating can provide lasting corrosion resistance for the substrate.