Preparation And Characterization Of Silicone Based Antifouling Coating With Surface-enriched Fouling Resistant Moieties

Marine biofouling refers to the adhesion,growth and accumulation of marine organisms on surface immersed in seawater.It adversely affects marine industries and exploration.Development of environmentally friendly and efficient antifouling coatings is of great economic values and strategic importance.Silicone based fouling release coatings(FRCs)are environmentally friendly,but their removal of accumulated fouling organisms needs high shear stress and they lack fouling resistant moieties,thus FRCs have poor antifouling ability under static conditions.In this thesis,we have developed silicone elastomer with amphiphilic side chains and zwitterionic side chains,respectively.Our aim is to develop a silicone antifouling system with surface-enriched fouling resistant moieties and improve the antifouling ability.(1)We synthesized an amphiphilic oligomer of dodecafluoroheptyl methacrylate(DFMA)and poly(ethylene glycol)methyl ether methacrylate(PEGMA)by telomerization using 3-mercaptopropyl trimethoxysilane(KH590)as the chain transfer reagent.The telomer was grafted to bis-silanol PDMS via condensation reaction to obtain a fouling resistant silicone based coating.X-ray photoelectron spectroscopy shows that there is more telomer on the surface than that in the bulk,indicating that the telomer is self-enriched onto the surface.The contact angle measurement reveals that the coating has low surface energy(18?22 m J/m~2)and hydrophobicity(91?110°).The water contact angle increases with the fluorocarbon content.The water contact angle decreases as PEG content increases after immersion in artificial seawater because of the restruction of PEG moieties.Atomic force microscopy measurement demonstrates that the coating has low elastic modulus(0.9?1.6 MPa).The addition of telomer has slight influence on the surface modulus of the coating.Pseudobarnacle removal test shows that the coating still has excellent fouling release property because the coating has low surface energy and low elastic modulus.More importantly,quartz crystal microbalance with dissipation and anti-biofouling adhesion test show that the coating can effectively inhibit the adsorption of protein,marine bacteria,biofilm as well as diatom.The coating with telomer under a suitable molar ratio of DFMA and PEGMA(1/2)has the best fouling resistant ability.(2)The fouling resistant ability of the coating is determined by the surface enrichment of amphiphilic telomer.We studied the effect of composition and structure on the property of the coating.The tack free time test shows that the curing rate can be controlled by changing the coating composition.The contact angle measurement reveals that the contact angle of the coating changes when the molar mass of poly(dimethylsiloxane)(PDMS),crosslinking agent and catalyst are changed.The coating which consists of PDMS(M_w=60000 g/mol),methyltriacetoxysilane and acetic acid has the lowest contact angle.Atomic force microscopy measurement shows that the elastic modulus decreases as the molar mass of PDMS,crosslinking agent and catalyst change.Pseudobarnacle removal test reveals that the coating has good fouling release ability.The coating consisting of PDMS of high molecular weight and acetic acid has the highest removal strength.The anti-protein test and antibiofouling adhesion test show that the coating consisting of PDMS of high molecular weight(M_w=60000g/mol),methyltriacetoxysilane and acetic acid has the optimal fouling resistant ability.(3)We synthesized a novel oligomer of zwitterionic monomer-tertiary carboxybetaine dodecafluoroheptyl ester ethyl acrylate(TCBF12)by telomerization using(3-mercaptopropyl)triethoxysilane(KH580)as the chain transfer reagent.Then the telomer was chemically grafted to bis-silanol PDMS by condensation reaction.During coating formation,the TCBF12 telomer can migrate onto the surface and be hydrolyzed into zwitterion when immersed in artificial seawater,yielding a zwitterion-enriched surface with improved fouling resistant ability.Meanwhile,the bulk of the coating can be kept hydrophobic without swelling.Attenuated total reflection infrared spectroscopy shows that the TCBF12 moieties on the surface are hydrolyzed into zwitterion after prehydrolysis.The reduction of contact angle after prehydrolysis reveals that there is zwitterion on the surface.Moreover,the water contact angle decreases as the content of telomer increases.The antibacterial test shows that the coating can effectively inhibit the adsorption of marine bacteria.