High Performance Marine Antibiofouling Polymeric Materials With Degradable Main Chain And Hydrolyzable Side Groups

Marine biofouling,the accumulation of diverse marine organisms on equipment surfaces under seawater,has detrimental impacts on marine industries and marine activities.In recent years,hydrolyzable polyacrylates based self-polishing coatings(SPCs)are the most widely used marine antifouling material.However,their surface self-renewal depends on water flow,leading to poor antifouling efficiency under static conditions.In addition,the non-degradable polymer chains into the ocean could causes marine plastic pollution,which is harmful to marine ecology.In this thesis,we prepared antifouling polymers with degradable main chain and hydrolyzable side chain,and studied their mechanical property,hydrolyzation/degradation and anti-biofouling property.The main results are as follows:(1)Degradable poly(ester-co-acrylate)with antifoulant pendant groups has been prepared by the radical ring-opening polymerization of 2-methylene-1,3-dioxepane(MDO),methyl methacrylate(MMA)and N-methacryloyloxy methyl benzoisothiazolinone(V-BIT).Such a polymer containing main chain esters can hydrolytically and enzymatically degrade.The degradation rates increase with main-chain ester content.Moreover,since the antifoulant groups are chemically grafted to the degradable main chain,their release can be controlled by the degradation besides the hydrolysis of side groups.Our study shows that the copolymer coating is efficient in inhibiting the accumulation of marine bacterial biofilm of Pseudomonas sp.and diatom Navicular incerta.Marine field test reveals that the copolymer has excellent efficiency in preventing biofouling for more than 6 months.(2)A novel hydrolysis-induced zwitterionic monomer-tertiary carboxybetaine triisopropylsilyl ester ethyl acrylate(TCBSA)was designed and copolymerized with methyl methacrylate(MMA).Such copolymer rapidly self-generates a zwitterionic surface and provides fouling resistance in marine environments.Furthermore,TCBSA was copolymerized with 2-methylene-1,3-dioxepane(MDO)and MMA,where MDO provides degradation to the polymers.Our study demonstrates that the degradation of the polymer is controlled,and the degradation rate increases with the external enzyme concentration in the seawater,leading to a self-renewing dynamic surface.Quartz crystal microbalance with dissipation(QCM-D)measurements show that the polymeric coating with self-generating zwitterions has excellent protein resistance in seawater.Bioassays demonstrate the coating can effectively inhibit the adhesion of marine bacteria(Pseudomonas sp.)and diatoms(Navicula incerta).(3)A single “kill-resist-renew trinity” polymeric coating integrating fouling killing,resistance,and releasing functions was reported in this study.To achieve the design,a novel monomer-tertiary carboxybetaine ester acrylate with the antifouling group N-(2,4,6-trichlorophenyl)maleimide(TCB-TCPM)was synthesized and copolymerized with copolymerized with MDO via radical ring-opening polymerization,yielding degradable polymers(PTMx).Attenuated total reflection infrared spectroscopy(ATR-IR)and X-ray photoelectron spectroscopy(XPS)tests reveal that PTMx coating can release the antifouling groups and form zwitterionic surfaces in seawater via hydrolysis.PTMx can form a selfrenewing surface via hydrolytic/enzymatic degradation,leading to the renewal of “kill-resist”surface,and the degradation rate increases with main chain esters content.QCM-D measurements reveal that the polymeric coating exhibits excellent protein resistance after hydrolysis.Bioassays demonstrate the coating can effectively inhibit the adhesion of marine bacteria through the synergistic effect of “attacking” antifouling groups and “defending”zwitterionic surface.(4)Hyperbranched polymers with degradable main chain were prepared by the copolymerization of MDO,vinyl acetate(VAc)and vinyl chloroacetate(VCAc)via selfcondensation vinyl polymerization(SCVP).The polymers were then grafted with ethyl dimethylaminopropionate to prepare zwitterionic precursor polymer with cationic groups(PMCx).The kinetics of polymerization reveal a similar reaction rate of MDO and vinyl ester monomer,leading to a random copolymer with main chain ester.ATR-IR test reveals that the side group can switch from cation to zwitterion via hydrolysis.Bioassays demonstrate the coating can kill the marine bacteria by cationic surface and resist the adhesion of bacteria by the self-generating zwitterionic surface after hydrolysis.(5)TCB-TCPM was copolymerized with methacrylic anhydride via reversible additionfragmentation chain transfer polymerization,yielding a degradable hyperbranched polymer.Such a polymer at the surface/seawater is able to hydrolyze and degrade to short segments forming a dynamic surface(releasing).The hydrolysis of TCB-TCPM generates the antifouling groups TCPM(killing)and zwitterionic groups(resistance).Such a polymeric coating exhibits a controllable degradation rate,which increases with the degrees of branching.The antibacterial assay demonstrates that the antifouling ability arise from the synergistic effect of “attacking”and “defending”.