Research And Development Of Environment-friendly Marine Anti-biofouling Coatings

With a title of "Research and Development of Environment-Friendly Marine Antifouling Coatings", this thesis focuses on the development of antifouling coatings with a self-generating hydrogel surface.In this thesis study, we investigatedeffects of hydrolyzable comonomer and cross-linking on anti-biofouling terpolymer coatings; successfully developedhybrid anti-biofouling coatings with a self-peeling andself-generated micro-structured soft and dynamic surface.In the development of this novel kind of marine anti-biofouling coatings, we first successfully synthesized a set of poly(methyl methacrylate-tributylsilyl methacrylate-acrylicacid) terpolymers. The solution of such terpolymer was crosslinked with polyfunctional aziridine just before and during the formation of eachcoating. The degradation rate, swelling ratio, changes of chemical structure, surfacehydrophilcityand characteristics of the coating after its immersion in seawater have been investigated by gravityanalysis, ATR-FTIR, contact angle and SEM. The antifouling properties of these newly developed coatings were tested in real sea environment. The results have showedthat after immersed in seawater, the water-contacted coating surface can gradually form a hydrogel layer containing carboxylic acids (anions) and this hydogel layer self-renews itself with further hydrolysis. The field tests have revealed that these self-generating and self-peeling hydrogel coatings aremuchbetterin antifouling than those control sampleswithout any cross-linking. The anti-biofouling ability increases with the hydrolysable comonomer content.Second, by varying the hydrolyzable monomer content and the cross-linking degree, a series of self-generating hydrogel surface coatingswere prepared.The effects of hydrolyzable comonomer and cross-linking on theirdegradation rate, swelling degree and surface hydrophilicity were further investigated. Their antifouling properties were evaluated by both the adsorption of fluorescence-labeled bovine serumalbumin and the field-testing in real marineenvironment. Our results have demonstrated that it is vitally important to delicately balance the hydrogel formation and the self-peeling rate to achieve the best antifouling ability by carefully choosing a proper cross-linking degree and a suitable content and type of the hydrolyzable comonomer. Further, we synthesized a high solid content poly(acrylamide-co-methacrylic acid)microgel with dispersion polymerization and mixed them with a self-peeling resin and a poly-functional cross-linking agent (axiridine) to form hybrid antifouling coatings that can form a self-generated topographical microgel surface with many tiny microgel bumps. The resin is a random terpolymer made of methyl methacrylate (MMA), acrylic acid (AA) and triisopropylsiyl methacrylate (TIPSM). After it is immersed into sea water, those microgels dispersed and embedded on the film surface are swollen, and at the same time, the hydrolysis of TIPSM makes the surface layer hydrophilic, forming a thin layer of hydrogel-like microstuctured soft and dynamic surface. The hydrolysis of TIPSM eventually makes the terpolymer chains on the surface soluble so that a thin layer on the coating surface is gradually dissolved and washed away and the inner layer is further exposed to sea water.We found some optimal composition at which the coatings showed an excellent antifouling property in the real field test.